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

PubMed

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.

Practicing ethnography in migration-related detention centers: A reflexive account.

PubMed

Esposito, Francesca

2017-01-01

Feminist scholars, as well as community psychologists, have advocated the role of reflexive engagement in the research process in order to challenge power relations. Moreover, the liberating potential of storytelling, especially when working with issues of diversity and marginalization, has been stressed. The purpose of this article is to reflect on an ethnographic work underway in the Identification and Expulsion Center-CIE of Ponte Galeria, Rome. How the researcher's identities, values, and experiences, alongside power and privilege, have influenced her positioning in the research setting and the relationships formed with the different setting members is the subject of discussion. In sharing the story of this work, the final intent is to contribute to the joint effort to foster a reflexive community psychology practice incorporating feminist goals and a dialogue about ethnography in community psychology.

Refractive Lens Exchange with Multifocal Intraocular Lens for Treatment of Chronic Intermittent Spasm of the Near Reflex

PubMed Central

Sallet, Guy

2017-01-01

We report the case of an emmetropic 32-year-old female with decreased uncorrected visual acuity and diplopia due to intermittent episodes of spasm of the near reflex. Neurologic, general, and ophthalmic examination could not find an organic cause. Attempts at spontaneous recovery, psychogenic therapy, and cycloplegic therapy were unsuccessful and the symptoms persisted for almost 5 years, leading to psychogenic distress. Final treatment with refractive lens exchange and implantation of a toric trifocal intraocular lens resolved the spasm of the near reflex, resulting in an uncorrected distance and near visual acuity of 20/20. PMID:29422856

Moving from Damage-Centered Research through Unsettling Reflexivity

ERIC Educational Resources Information Center

Calderon, Dolores

2016-01-01

The author revisits autoethnographic work in order to examine how she unwittingly incorporated damage-centered (Tuck 2009) research approaches that reproduce settler colonial understandings of marginalized communities. The paper examines the reproduction of settler colonial knowledge in ethnographic research by unearthing the inherent surveillance…

The effect of instrument alignment on peripheral refraction measurements by automated optometer.

PubMed

Ehsaei, Asieh; Chisholm, Catharine M; Mallen, Edward A H; Pacey, Ian E

2011-07-01

Interest in peripheral refraction measurement has grown in recent years in response to the insight it may provide into myopia development. In light of the likely increase in the clinical use of open-field autorefractors for peripheral refraction measurements, the question of instrument alignment and its impact on the accuracy of refraction measurements is raised. The aim of this study was to investigate the accuracy and precision when an open-field device was moved away from alignment with the corneal reflex towards the pupil margins, and to determine the optimum alignment position for peripheral refraction measurements. Autorefractions were performed on the right eyes of 10 healthy participants using the Shin-Nippon NVision-K 5001 autorefractor. At least five measurements were taken with the subject fixating a distance target in the primary position of gaze, and then four peripheral fixation targets located along the horizontal meridian (10° and 20° eccentricities in the nasal and temporal retina). Measurements were taken at seven alignment positions across the pupil for each fixation angle. Refraction was recorded as the spherical and cylindrical power. The central objective refraction achieved under cycloplegia based on the autorefraction result for the whole sample, ranged between -5.62 D and +1.85 D for the value of sphere, with a maximum astigmatism of -1.00 D. Acceptable alignment position range varied with fixation angle but was -1.0 to +1.0 mm in width across the pupil. Peripheral refraction measurements centred on the entrance pupil were as reliable as those centred on the corneal reflex. Our data suggest that for peripheral refraction measurements, there is a range of acceptable positions and operators can be confident of the validity of results obtained if aligned half way between the pupil centre and corneal reflex. The alignment becomes more critical at greater eccentricities. Ophthalmic & Physiological Optics © 2011 The College of Optometrists.

Three-dimensional and topographic relationships between the orbital margins with reference to assessment of eyeball protrusion.

PubMed

Shin, Kang-Jae; Lee, Shin-Hyo; Koh, Ki-Seok; Song, Wu-Chul

2017-03-01

This study investigated the topographic relationships among the eyeball and four orbital margins with the aim of identifying the correlation between orbital geometry and eyeball protrusion in Koreans. Three-dimensional (3D) volume rendering of the face was performed using serial computed-tomography images of 141 Koreans, and several landmarks on the bony orbit and the cornea were directly marked on the 3D volumes. The anterior-posterior distances from the apex of the cornea to each orbital margin and between the orbital margins were measured in both eyes. The distances from the apex of the cornea to the superior, medial, inferior, and lateral orbital margins were 5.8, 5.8, 12.0, and 17.9 mm, respectively. Differences between sides were observed in all of the orbital margins, and the distances from the apex of the cornea to the superior and inferior orbital margins were significantly greater in females than in males. The anterior-posterior distance between the superior and inferior orbital margins did not differ significantly between males (6.3 mm) and females (6.2 mm). The data obtained in this study will be useful when developing practical guidelines applicable to forensic facial reconstruction and orbitofacial surgeries.

Surface EMG crosstalk during phasic involuntary muscle activation in the nociceptive withdrawal reflex.

PubMed

Frahm, Ken S; Jensen, Michael B; Farina, Dario; Andersen, Ole K

2012-08-01

The human nociceptive withdrawal reflex is typically assessed using surface electromyography (sEMG). Based on sEMG, the reflex receptive field (RRF) can be mapped. However, EMG crosstalk can cause erroneous results in the RRF determination. Single differential (SD) vs. double differential (DD) surface EMG were evaluated. Different electrode areas and inter-electrode-distances (IED) were evaluated. The reflexes were elicited by electrical stimulation of the sole of the foot. EMG was obtained from both tibialis anterior (TA) and soleus (SOL) using both surface and intramuscular EMG (iEMG). The amount of crosstalk was significantly higher in SD recordings than in DD recordings (P < 0.05). Crosstalk increased when electrode measuring area increased (P < 0.05) and when IED increased (P < 0.05). Reflex detection sensitivity decreases with increasing measuring area and increasing IED. These results stress that for determination of RRF and similar tasks, DD recordings should be applied. Copyright © 2012 Wiley Periodicals, Inc.

Wh-filler-gap dependency formation guides reflexive antecedent search

PubMed Central

Frazier, Michael; Ackerman, Lauren; Baumann, Peter; Potter, David; Yoshida, Masaya

2015-01-01

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 (Experiments 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. PMID:26500579

Reflexivity, critical qualitative research and emancipation: a Foucauldian perspective.

PubMed

McCabe, Janet L; Holmes, Dave

2009-07-01

In this paper, we consider reflexivity, not only as a concept of qualitative validity, but also as a tool used during the research process to achieve the goals of emancipation that are intrinsic to qualitative research conducted within a critical paradigm. Research conducted from a critical perspective poses two challenges to researchers: validity of the research must be ensured and the emancipatory aims of the research need to be realized and communicated. The traditional view of reflexivity as a means of ensuring validity in qualitative research limits its potential to inform the research process. The Medline and CINAHL data bases were searched (1998-2008 inclusive) using keywords such as reflexivity, validity, subjectivity, bias, emancipation, empowerment and disability. In addition, the work of Michel Foucault was examined. Using the work of the late French philosopher Michel Foucault, we explore how Foucault's 'technologies of the self' can be employed during critical qualitative research to achieve emancipatory changes. Using research conducted with marginalized populations as an example (specifically, individuals with disabilities), we demonstrate the potential for using reflexivity, in a Foucauldian sense, during the research process. Shifting the traditional view of reflexivity allows researchers to focus on the subtle changes that comprise emancipation (in a Foucauldian sense). As a result, researchers are better able to see, understand and analyse this process in both the participants and themselves.

Does the distance between tumor and margin in radical prostatectomy specimens correlate with prognosis: relation to tumor location.

PubMed

Paluru, Swetha; Epstein, Jonathan I

2016-10-01

The posterior half of the prostate has a smooth well-defined edge unlike anteriorly. Often, tumor extends close to the posterior margin, where it is controversial whether pathologists should measure the distance between the tumor and the margin. There are no published data regarding the significance of a close margin factoring in the anatomical location within the radical prostatectomy (RP). We identified 158 RPs with 39 anterior-predominant carcinomas and 119 cases with posterior-predominant cancer. Distances between the tumor and inked margin were measured with an ocular micrometer. Eighty-seven cases had no progression with a minimum 6-year follow-up (median, 8; range, 6-9). Eighteen cases had progression with a median time to progression of 2 years with all men progressing within 6 years after RP. There was no statistically significant difference in the risk of progression relative to distance of tumor to the posterior margin (P=.09). The mean distance of tumor to the anterior margin for the cases that progressed was 0.6 mm (median, 0.5 mm; range, 0.05-1.18) compared to 1.9 mm (median, 1.1; range, 0.02-4) for the cases that did not progress (P=.02). Of 7 cases with anterior-predominant tumors that progressed, 5 had tumor located less than 1 mm from the anterior margin. In conclusion, if cancer is present less than 1 mm from the anterior margin, there is an increased tendency to recur, and this finding should be included in pathology reports. However, close margins posteriorly are not clinically significant and should not be reported. Copyright © 2016 Elsevier Inc. All rights reserved.

Three-dimensional and topographic relationships between the orbital margins with reference to assessment of eyeball protrusion

PubMed Central

Shin, Kang-Jae; Lee, Shin-Hyo; Koh, Ki-Seok

2017-01-01

This study investigated the topographic relationships among the eyeball and four orbital margins with the aim of identifying the correlation between orbital geometry and eyeball protrusion in Koreans. Three-dimensional (3D) volume rendering of the face was performed using serial computed-tomography images of 141 Koreans, and several landmarks on the bony orbit and the cornea were directly marked on the 3D volumes. The anterior-posterior distances from the apex of the cornea to each orbital margin and between the orbital margins were measured in both eyes. The distances from the apex of the cornea to the superior, medial, inferior, and lateral orbital margins were 5.8, 5.8, 12.0, and 17.9 mm, respectively. Differences between sides were observed in all of the orbital margins, and the distances from the apex of the cornea to the superior and inferior orbital margins were significantly greater in females than in males. The anterior-posterior distance between the superior and inferior orbital margins did not differ significantly between males (6.3 mm) and females (6.2 mm). The data obtained in this study will be useful when developing practical guidelines applicable to forensic facial reconstruction and orbitofacial surgeries. PMID:28417054

Multi-Reflex Propulsion Systems for Space and Air Vehicles and Energy Transfer for Long Distance

NASA Astrophysics Data System (ADS)

Bolonkin, A.

The purpose of this article is to call attention to the revolutionary idea of light multi-reflection. This idea allows the design of new engines, space and air propulsion systems, storage (of a beam and solar energy), transmitters of energy (to millions of kilometers), creation of new weapons, etc. This method and the main innovations were offered by the author in 1983 in the former USSR. Now the author shows in a series of articles the immense possibilities of this idea in many fields of engineering - astronautics, aviation, energy, optics, direct converter of light (laser beam) energy to mechanical energy (light engine), to name a few. This article considers the multi-reflex propulsion systems for space and air vehicles and energy transmitter for long distances in space.

Measurement of the Area of Corneal Exposure Using Digital Image and Its Application During Assessment for Blepharoplasty.

PubMed

Park, Kisoo; Guo, Ziyi; Park, Dae Hwan

2018-02-01

The normal morphological and functional values of orbits vary according to race, sex, and age. We measured the palpebral fissure using the marginal reflex distance (MRD 1 ), marginal limbal distance (MLD), and vertical height of the palpebral fissure (VHPF). Unfortunately, these measurements are all one-dimensional figures that measure the distance between two points; they have limitations when it comes to measuring the three-dimensional ocular surface. Therefore, this study used the area of corneal exposure (ACE), which shows a two-dimensional area, to measure changes between the sizes of eyes according to age. This study was conducted using preoperative photographs of Koreans in Daegu city, Korea, who underwent plastic surgery in our department except for eyelid surgery. We divided the subjects into eight groups, including ten males and ten females in each decade of age, from age 10 to over 80 years. A total of 160 people were recruited who were followed up for photograph analysis using Adobe Photoshop 7.0 software. In terms of the mean value, the ACEs were 73.3 ± 2% in male subjects and 77.1 ± 2% in female subjects, and values for female subjects were greater than those for male subjects (p < 0.05). Significant differences in ACEs were observed according to age. The peak level of growth in the ACE was reached between 20 and 29 years of age. After the 20 s, a gradual decrease was observed (p < 0.05). The peak level of growth in the ACE was reached between 20 and 29 years of age. The growth pattern can be classified as continuously decreasing after reaching the peak level. The data from this study are significant in that they can be used as comprehensive data for normal eyelid values according to age. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Still on the Margins: Migration, English Language Learning, and Mental Health in Immigrant Psychiatric Patients

ERIC Educational Resources Information Center

Eamer, Allyson; Fernando, Shanti; King, Alyson E.

2017-01-01

This qualitative study explores the reflexive relationships among mental illness, acculturation, and progress toward English proficiency in five adult immigrants being treated at a Canadian psychiatric hospital. The research explores the additional challenges faced by mentally ill individuals when learning a new language and the extent to which…

Feasibility of Using the Marginal Blood Vessels as Reference Landmarks for CT Colonography

PubMed Central

Wei, Zhuoshi; Yao, Jianhua; Wang, Shijun; Liu, Jiamin; Dwyer, Andrew J.; Pickhardt, Perry J.; Nowinski, Wieslaw L.; Summers, Ronald M.

2015-01-01

OBJECTIVE The purpose of this study was to show the spatial relationship of the colonic marginal blood vessels and the teniae coli on CT colonography (CTC) and the use of the marginal blood vessels for supine-prone registration of polyps and for determination of proper connectivity of collapsed colonic segments. MATERIALS AND METHODS We manually labeled the marginal blood vessels on 15 CTC examinations. Colon segmentation, centerline extraction, teniae detection, and teniae identification were automatically performed. For assessment of their spatial relationships, the distances from the marginal blood vessels to the three teniae coli and to the colon were measured. Student t tests (paired, two-tailed) were performed to evaluate the differences among these distances. To evaluate the reliability of the marginal vessels as reference points for polyp correlation, we analyzed 20 polyps from 20 additional patients who underwent supine and prone CTC. The average difference of the circumferential polyp position on the supine and prone scans was computed. Student t tests (paired, two-tailed) were performed to evaluate the supine-prone differences of the distance. We performed a study on 10 CTC studies from 10 patients with collapsed colonic segments by manually tracing the marginal blood vessels near the collapsed regions to resolve the ambiguity of the colon path. RESULTS The average distances (± SD) from the marginal blood vessels to the tenia mesocolica, tenia omentalis, and tenia libera were 20.1 ± 3.1 mm (95% CI, 18.5–21.6 mm), 39.5 ± 4.8 mm (37.1–42.0 mm), and 36.9 ± 4.2 mm (34.8–39.1 mm), respectively. Pairwise comparison showed that these distances to the tenia libera and tenia omentalis were significantly different from the distance to the tenia mesocolica (p < 0.001). The average distance from the marginal blood vessels to the colon wall was 15.3 ± 2.0 mm (14.2–16.3 mm). For polyp localization, the average difference of the circumferential polyp position on the supine and prone scans was 9.6 ± 9.4 mm (5.5–13.7 mm) (p = 0.15) and expressed as a percentage of the colon circumference was 3.1% ± 2.0% (2.3–4.0%) (p = 0.83). We were able to trace the marginal blood vessels for 10 collapsed colonic segments and determine the paths of the colon in these regions. CONCLUSION The marginal blood vessels run parallel to the colon in proximity to the tenia mesocolica and enable accurate supine-prone registration of polyps and localization of the colon path in areas of collapse. Thus, the marginal blood vessels may be used as reference landmarks complementary to the colon centerline and teniae coli. PMID:24370165

The Agendas of Distance Teaching Universities: Moving from the Margins to the Center Stage of Higher Education.

ERIC Educational Resources Information Center

Guri-Rosenblit, Sarah

1999-01-01

Examined from a comparative perspective the extent to which the agendas of distance teaching universities have moved from the margins to the center stage of higher education. Demonstrates that the boundaries between distance and campus universities are blurring and converging, and that future relations between them will be marked by competition…

Signal processing related to the vestibulo-ocular reflex during combined angular rotation and linear translation of the head

NASA Technical Reports Server (NTRS)

McCrea, R. A.; Chen-Huang, C.; Peterson, B. W. (Principal Investigator)

1999-01-01

The contributions of vestibular nerve afferents and central vestibular pathways to the angular (AVOR) and linear (LVOR) vestibulo-ocular reflex were studied in squirrel monkeys during fixation of near and far targets. Irregular vestibular afferents did not appear to be necessary for the LVOR, since when they were selectively silenced with galvanic currents the LVOR was essentially unaffected during both far- and near-target viewing. The linear translation signals generated by secondary AVOR neurons in the vestibular nuclei were, on average, in phase with head velocity, inversely related to viewing distance, and were nearly as strong as AVOR-related signals. We suggest that spatial-temporal transformation of linear head translation signals to angular eye velocity commands is accomplished primarily by the addition of viewing distance multiplied, centrally integrated, otolith regular afferent signals to angular VOR pathways.

Asymmetry and polarity of the South Atlantic conjugated margins related to the presence of cratons: a numerical study

NASA Astrophysics Data System (ADS)

Andrés-Martínez, Miguel; Pérez-Gussinyé, Marta; de Monserrat Navarro, Albert; Morgan, Jason P.

2015-04-01

Tectonic asymmetry of conjugated passive margins, where one margin is much narrower than the conjugate one, is commonly observed at many passive margins world-wide. Conjugate margin asymmetry has been suggested to be a consequence of lateral changes in rheology, composition, temperature gradient or geometries of the crust and lithosphere. Here we use the South Atlantic margins (from Camamu/Gabon to North Santos/South Kwanza) as a natural laboratory to understand conjugate margin asymmetry. Along this margin sector the polarity of the asymmetry changes. To the North, the Brazilian margin developed in the strong Sao Francisco craton, and this constitutes the narrow side of the conjugate pair. To the South, the Brazilian margin developed in the Ribeira fold belt, and the margin is wide. The opposite is true for the African side. We have thus numerically analysed how the relative distance between the initial location of extension and the craton influences the symmetry/asymmetry and polarity of the conjugate margin system. Our numerical model is 2D visco-elasto-plastic and has a free surface, strain weakening and shear heating. The initial set-up includes a cratonic domain, a mobile belt and a transition area between both. We have run tests with different rheologies, thickness of the lithosphere, and weak seeds at different distances from the craton. Results show asymmetric conjugated margins, where the narrower margin is generally the closest to the craton. Our models also allow us to study how the polarity is controlled by the distance between the initial weakness and the craton, and help to understand how the presence of cratonic domains affects the final architecture of the conjugated margins.

Precise Distances for Main-belt Asteroids in Only Two Nights

NASA Astrophysics Data System (ADS)

Heinze, Aren N.; Metchev, Stanimir

2015-10-01

We present a method for calculating precise distances to asteroids using only two nights of data from a single location—far too little for an orbit—by exploiting the angular reflex motion of the asteroids due to Earth’s axial rotation. We refer to this as the rotational reflex velocity method. While the concept is simple and well-known, it has not been previously exploited for surveys of main belt asteroids (MBAs). We offer a mathematical development, estimates of the errors of the approximation, and a demonstration using a sample of 197 asteroids observed for two nights with a small, 0.9-m telescope. This demonstration used digital tracking to enhance detection sensitivity for faint asteroids, but our distance determination works with any detection method. Forty-eight asteroids in our sample had known orbits prior to our observations, and for these we demonstrate a mean fractional error of only 1.6% between the distances we calculate and those given in ephemerides from the Minor Planet Center. In contrast to our two-night results, distance determination by fitting approximate orbits requires observations spanning 7-10 nights. Once an asteroid’s distance is known, its absolute magnitude and size (given a statistically estimated albedo) may immediately be calculated. Our method will therefore greatly enhance the efficiency with which 4m and larger telescopes can probe the size distribution of small (e.g., 100 m) MBAs. This distribution remains poorly known, yet encodes information about the collisional evolution of the asteroid belt—and hence the history of the Solar System.

Release brochure for Amethyst Germplasm Hoary Tansyaster (Machaeranthera canescens)

Treesearch

Derek Tilley

2014-01-01

Hoary tansyaster is a short-lived perennial forb with pale to dark purple flowers. Plants are 6 to 30 inches tall with diffuse branching. Leaves are about 2 inches long and oblong or lance shaped with entire to sharply toothed margin. The flower heads have many subtending bracts that reflex away from the flower at the tip. These bracts are white and membranous at the...

Plant Guide: Hoary tansyaster (Machaeranthera canescens)

Treesearch

Derek Tilley; Dan Ogle; Loren St. John

2014-01-01

Sunflower family (Asteraceae). Hoary tansyaster is a short-lived perennial forb with pale to dark purple flowers. Plants are 15 to 75 cm (6 to 30 in) tall with diffuse branching. Leaves are about 5 cm (2 in) long and 6 mm (0.25 in) wide, oblong or lance shaped with entire to sharply toothed margin. Flower heads have many subtending bracts that reflex away from the...

Cultural Reflexivity in Health Research and Practice

PubMed Central

Aronowitz, Robert; Deener, Andrew; Keene, Danya; Schnittker, Jason

2015-01-01

Recent public health movements have invoked cultural change to improve health and reduce health disparities. We argue that these cultural discourses have sometimes justified and maintained health inequalities when those with power and authority designated their own social practices as legitimate and healthy while labeling the practices of marginalized groups as illegitimate or unhealthy. This “misrecognition,” which creates seemingly objective knowledge without understanding historical and social conditions, sustains unequal power dynamics and obscures the fact that what is deemed legitimate and healthy can be temporally, geographically, and socially relative. We use examples from research across multiple disciplines to illustrate the potential consequences of cultural misrecognition, highlight instances in which culture was invoked in ways that overcame misrecognition, and discuss how cultural reflexivity can be used to improve health research and practice. PMID:25905833

A combined stereo-photogrammetry and underwater-video system to study group composition of dolphins

NASA Astrophysics Data System (ADS)

Bräger, S.; Chong, A.; Dawson, S.; Slooten, E.; Würsig, B.

1999-11-01

One reason for the paucity of knowledge of dolphin social structure is the difficulty of measuring individual dolphins. In Hector's dolphins, Cephalorhynchus hectori, total body length is a function of age, and sex can be determined by individual colouration pattern. We developed a novel system combining stereo-photogrammetry and underwater-video to record dolphin group composition. The system consists of two downward-looking single-lens-reflex (SLR) cameras and a Hi8 video camera in an underwater housing mounted on a small boat. Bow-riding Hector's dolphins were photographed and video-taped at close range in coastal waters around the South Island of New Zealand. Three-dimensional, stereoscopic measurements of the distance between the blowhole and the anterior margin of the dorsal fin (BH-DF) were calibrated by a suspended frame with reference points. Growth functions derived from measurements of 53 dead Hector's dolphins (29 female : 24 male) provided the necessary reference data. For the analysis, the measurements were synchronised with corresponding underwater-video of the genital area. A total of 27 successful measurements (8 with corresponding sex) were obtained, showing how this new system promises to be potentially useful for cetacean studies.

Diagnostic value of repeated ice tests in the evaluation of ptosis in myasthenia gravis.

PubMed

Park, Jun Young; Yang, Hee Kyung; Hwang, Jeong-Min

2017-01-01

Twenty-six patients with ptosis related to Myasthenia gravis (MG) and 38 controls with ptosis other than MG were included. All patients were tested with the ice test 2 times on separate days in the afternoon. The margin reflex distance (MRD) was measured before and immediately after 2-minute application of ice on the eyelids. The ice test was judged positive if there was an improvement of at least 2.0 mm of MRD after the ice test. Among the patients with negative test results, 'equivocal' was defined by improvement of MRD from at least 1.0 mm to less than 2.0 mm after the ice test. Repeated ice test results showed an agreement of 61.5% in MG, and 97.4% in nonmyasthenic ptosis. Repeated ice tests increased the sensitivity by 34.6% compared to a single test. Among the patients with repeatedly negative test results, 63.6% of those who showed equivocal results at least once turned out to be MG. Of those with repeated non-equivocal negative results, nobody turned out to be MG. There was no significant difference of the ice test results between ocular MG and generalized MG (p = 0.562).

Diagnostic value of repeated ice tests in the evaluation of ptosis in myasthenia gravis

PubMed Central

2017-01-01

Twenty-six patients with ptosis related to Myasthenia gravis (MG) and 38 controls with ptosis other than MG were included. All patients were tested with the ice test 2 times on separate days in the afternoon. The margin reflex distance (MRD) was measured before and immediately after 2-minute application of ice on the eyelids. The ice test was judged positive if there was an improvement of at least 2.0 mm of MRD after the ice test. Among the patients with negative test results, 'equivocal’ was defined by improvement of MRD from at least 1.0 mm to less than 2.0 mm after the ice test. Repeated ice test results showed an agreement of 61.5% in MG, and 97.4% in nonmyasthenic ptosis. Repeated ice tests increased the sensitivity by 34.6% compared to a single test. Among the patients with repeatedly negative test results, 63.6% of those who showed equivocal results at least once turned out to be MG. Of those with repeated non-equivocal negative results, nobody turned out to be MG. There was no significant difference of the ice test results between ocular MG and generalized MG (p = 0.562). PMID:28562609

[A new method to test vertical ocular deviations using perilimbal light reflexes].

PubMed

Breyer, Armin; Rütsche, Adrian; Gampe, Elisabeth; Mojon, Daniel S

2003-03-01

To develop a new diagnostic technique to determine vertical ocular deviations when the center of the pupil is covered by swollen eyelids in up- and downgaze. In upgaze (downgaze) the reflex of a diagnostic lamp held at about 50 cm distance from the patient is observed on the lower (upper) limbus. In the case of an asymmetric reflex, prisms are used to obtain symmetrical reflexes. The amount of prisms indicates the size of the vertical misalignment. In five healthy volunteers, the angles of vertical changes of gaze position were plotted against the prism size needed to recenter the perilimbal reflex. There was a linear correlation between the amount of upgaze changes in degrees and the strength of prisms used for compensation in degrees. This linear correlation was also found in downgaze. For both the correlation coefficient was r = 0.98 +/- 0.01. In upgaze the slope of the average regression line was 0.55 +/- 2.3 degrees, in downgaze - 4.1 +/- 0.8 degrees. A prism of 1 degrees corresponds in upgaze to a vertical deviation of about 1.3 +/- 0.14 degrees, in downgaze to a deviation of about 1.1 +/- 0.07 degrees. These results demonstrate that the perilimbal light reflex test is suitable for measuring simulated vertical ocular deviations. Therefore, the test may also be used in patients with vertical deviations who cannot be measured with classical methods. The method is more exact for measurements in upgaze.

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

PubMed

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.

Surgical margin-negative endoscopic mucosal resection with simple three-clipping technique: a randomized prospective study (with video).

PubMed

Mori, Hirohito; Kobara, Hideki; Nishiyama, Noriko; Fujihara, Shintaro; Kobayashi, Nobuya; Ayaki, Maki; Masaki, Tsutomu

2016-11-01

Although endoscopic mucosal resection is an established colorectal polyp treatment, local recurrence occurs in 13 % of cases due to inadequate snaring. We evaluated whether pre-clipping to the muscularis propria resulted in resected specimens with negative surgical margins without thermal denaturation. Of 245 polyps from 114 patients with colorectal polyps under 20 mm, we included 188 polyps from 81 patients. We randomly allocated polyps to the conventional injection group (CG) (97 polyps) or the pre-clipping injection group (PG) (91 polyps). The PG received three-point pre-clipping to ensure ample gripping to the muscle layer on the oral and both sides of the tumor with 4 mL local injection. Endoscopic ultrasonography was performed to measure the resulting bulge. Outcomes included the number of instances of thermal denaturation of the horizontal/vertical margin (HMX/VMX) or positive horizontal/vertical margins (HM+/VM+), the shortest distance from tumor margins to resected edges, and the maximum bulge distances from tumor surface to the muscularis propria. The numbers of HMX and HM+ in the CG and PG were 27 and 6, and 9 and 2 (P = 0.001), and VMX and VM+ were 8 and 5, and 0 and 0 (P = 0.057). The shortest distance from tumor margin to resected edge [median (range), mm] in polyps in the CG and PG was 0.6 (0-2.7) and 4.7 (2.1-8.9) (P = 0.018). The maximum bulge distances were 4.6 (3.0-8.0) and 11.0 (6.8-17.0) (P = 0.005). Pre-clipping enabled surgical margin-negative resection without thermal denaturation.

Evolved dispersal strategies at range margins

PubMed Central

Dytham, Calvin

2009-01-01

Dispersal is a key component of a species's ecology and will be under different selection pressures in different parts of the range. For example, a long-distance dispersal strategy suitable for continuous habitat at the range core might not be favoured at the margin, where the habitat is sparse. Using a spatially explicit, individual-based, evolutionary simulation model, the dispersal strategies of an organism that has only one dispersal event in its lifetime, such as a plant or sessile animal, are considered. Within the model, removing habitat, increasing habitat turnover, increasing the cost of dispersal, reducing habitat quality or altering vital rates imposes range limits. In most cases, there is a clear change in the dispersal strategies across the range, although increasing death rate towards the margin has little impact on evolved dispersal strategy across the range. Habitat turnover, reduced birth rate and reduced habitat quality all increase evolved dispersal distances at the margin, while increased cost of dispersal and reduced habitat density lead to lower evolved dispersal distances at the margins. As climate change shifts suitable habitat poleward, species ranges will also start to shift, and it will be the dispersal capabilities of marginal populations, rather than core populations, that will influence the rate of range shifting. PMID:19324810

Concordance of gross surgical and final fixed margins in vulvar intraepithelial neoplasia 3 and vulvar cancer.

PubMed

DeSimone, Christopher P; Crisp, Meredith P; Ueland, Frederick R; DePriest, Paul D; van Nagell, John R; Lele, Subodh M; Modesitt, Susan C

2006-08-01

To prospectively evaluate the concordance of initial surgical vulvar margins and final fixed margins and to determine the amount of microscopic pathology of grossly negative margins in women with vulvar intraepithelial neoplasia (VIN) 3 or vulvar carcinoma. Women with VIN 3 or vulvar carcinoma undergoing surgical excision were identified. Prior to excision, acetic acid was used to highlight the lesions, and 2 sutures were placed, 1 at the edge of gross disease and another 1 cm distal from the first. After specimen removal and fixation, the distance between sutures and microscopic involvement of VIN was determined. Twenty-seven women were enrolled; however, only 19 had final fixed specimens that could be accurately measured. The median fixed distance of the vulvar margin was 0.85 cm (mean, 0.83; SD, 0.19) as compared to the gross, 1-cm margin (p = 0.001). Three subjects (16%) had microscopic involvement by VIN 3 in the grossly negative epithelium between the 2 sutures, but none had a positive peripheral margin. The gross surgical margin after vulvar resection is reduced by 15% when measured in its final fixed state, and a grossly negative 1-cm margin will seldom harbor significant disease.

Determination of safe margin in the surgical pathologic specimens of non-small cell carcinoma of the lung.

PubMed

Feizi, Iraj; Sokouti, Mohsen; Golzari, Samad E J; Gojazede, Morteza; Farahnak, Mohammad Reza; Hashemzadeh, Shahriar; Rahimi-Rad, Mohammad Hossein

2013-01-01

Local recurrences of the tumor at the surgical margin are serious problems in pulmonary resections for lung cancer. The aim of this study is to determine the involved margins and safe distances of the resection sites from tumor for prevention of local recurrences. In this prospective study, 66 patients operated for non-small cell lung carcinoma (NSCLC) from Jan 2006 to Sep 2008 were evaluated. After performing pulmonary resections, multiple biopsies were taken up from 5 mm (A), 10 mm (B), 15 mm (C), and 20 mm (D) distance from tumor. The specimens were studied histopathologically. From a total of66 patients with NSCLC admitted to our referral hospital, 25 (38%) had adenocarcinoma, 18 (27.3%) squamous cell carcinoma, 5 (7.5%) large cell carcinoma, 4 (6%) bronchoalveolar cell carcinoma, 4 (6%) adenoid cystic carcinoma, 3 (4.6%) malignant carcinoid tumor and 7 (10.6%) had metastasis. The most common symptoms were dyspnea and cough. Histopathologically tumor positive margins were found in 84.8% (A), 10.6% (B), 4.5% (C), and 0% (D). There was a significant statistically difference between tumor involvement at distances 5 mm (A) versus 10-20 mm (B-D) (P <0.001). A 20 mm distance from the gross tumor is considered as a safe surgical margin in any type of malignant pulmonary resections for prevention of local surgical recurrences if there was no pathologic examination before surgery.

The Interaction of Contextual and Syntactic Information in the Processing of Turkish Anaphors.

PubMed

Gračanin-Yuksek, Martina; Lago, Sol; Şafak, Duygu Fatma; Demir, Orhan; Kırkıcı, Bilal

2017-12-01

In contrast with languages where anaphors can be classified into pronouns and reflexives, Turkish has a tripartite system that consists of the anaphors o, kendi, and kendisi. The syntactic literature on these anaphors has proposed that whereas o behaves like a pronoun and kendi behaves like a reflexive, kendisi has a more flexible behavior and it can function as both a pronoun and a reflexive. Using acceptability judgments and a self-paced reading task, we examined how Turkish anaphors are processed in isolated sentences and within larger discourse contexts. We manipulated contextual information by creating passages where the context favored a local, long-distance or extra-sentential referent prior to the appearance of the anaphor. We measured the effect of the context on participants' reading times and their end-of-trial coreference assignments. Our results suggest that contextual information affects the interpretive possibilities associated with an anaphor, but that the influence of context depends on the degree to which the anaphor is syntactically constrained.

Circumferential fit assessment of CAD/CAM single crowns--a pilot investigation on a new virtual analytical protocol.

PubMed

Matta, Ragai E; Schmitt, Johannes; Wichmann, Manfred; Holst, Stefan

2012-10-01

Techniques currently applied to determine the marginal accuracy of dental crown restorations yield inadequate information. This investigation aimed to test a new virtual approach for determining the precision of fit of single-crown copings. Zirconia single crown copings were manufactured on 10 gypsum, single-tooth master casts with two different established computer-aided design/computer-assisted manufacture (CAD/CAM) systems (groups A and B). After cementation, the circumferential fit was assessed with an industrial noncontact scanner and virtual 3D analysis, following a triple-scan protocol. Marginal fit was determined by virtual sectioning; each abutment-coping complex was digitally sliced in 360 vertical sections (1 degree per section). Standardized measurement distances for analyzing the marginal fit (z, xy, xyz) were selected, and a crosshair alignment was utilized to determine whether crowns were horizontally and/or vertically too large or small. The Mann-Whitney test was applied to test for differences between groups. Significant differences in the xy direction (P = .008) were measured between groups. Group A showed a greater number of horizontally overextended margins and a higher frequency of xy distances greater than 150 Μm, in addition to a tendency for excessive z distances (P = .095). The mean marginal gap values were clinically acceptable in the present investigation; however, a full circumferential analysis revealed significant differences in marginal coping quality.

Causes and Surgical Outcomes of Lower Eyelid Retraction

PubMed Central

Kim, Kun Hae; Baek, Ji Sun; Lee, Saem; Lee, Jung Hye; Choi, Hye Sun; Kim, Sung Joo

2017-01-01

Purpose To investigate the causes of lower eyelid retraction and evaluate the outcomes of various surgical procedures. Methods We conducted a retrospective medical record review of patients who underwent lower eyelid retraction surgery performed by a single surgeon at Kim's Eye Hospital between 2006 and 2013. We investigated the causes of lower eyelid retraction, clinical history, characteristics, treatment, and surgical outcomes. Preoperative and postoperative margin reflex distance 2 and inferior scleral show were measured for each eyelid. Success was defined as a positive eyelid elevation and a decrease in inferior scleral show. Results A total of 19 lower eyelids were treated in 14 patients with lower eyelid retraction. For cosmetic reasons, surgical correction for congenital lower eyelid retraction was performed on seven eyelids (36.8%). Ten eyelids (52.6%) exhibited secondary lower eyelid retraction after surgery. One eyelid (5.3%) was affected by facial palsy and one eyelid (5.3%) exhibited exophthalmos of an unknown origin. We adopted a selective approach based on lower eyelid retraction severity. Spacer grafting via a subconjunctival approach was the most commonly performed surgical technique (13 eyelids, 68.4%). The lateral tarsal strip procedure was used to horizontally tighten three eyelids (15.8%). At the time of the procedure, one of these eyelids (5.3%) also received an adjuvant suborbicularis oculi fat lift. Autogenous dermis fat grafting was performed on two lower eyelids (10.5%), whose retraction was caused by fat and soft tissue loss. Cosmetic outcomes were satisfactory in all cases. Conclusions To achieve satisfactory surgical outcomes, surgeons should adopt an approach based on the severity of lower eyelid retraction. Mild lower eyelid retraction can be corrected without grafts. When retraction is severe and exceeds 2 mm, spacer grafts that push the lower eyelid margin upwards and support it from below are required. PMID:28682021

Causes and Surgical Outcomes of Lower Eyelid Retraction.

PubMed

Kim, Kun Hae; Baek, Ji Sun; Lee, Saem; Lee, Jung Hye; Choi, Hye Sun; Kim, Sung Joo; Jang, Jae Woo

2017-08-01

To investigate the causes of lower eyelid retraction and evaluate the outcomes of various surgical procedures. We conducted a retrospective medical record review of patients who underwent lower eyelid retraction surgery performed by a single surgeon at Kim's Eye Hospital between 2006 and 2013. We investigated the causes of lower eyelid retraction, clinical history, characteristics, treatment, and surgical outcomes. Preoperative and postoperative margin reflex distance 2 and inferior scleral show were measured for each eyelid. Success was defined as a positive eyelid elevation and a decrease in inferior scleral show. A total of 19 lower eyelids were treated in 14 patients with lower eyelid retraction. For cosmetic reasons, surgical correction for congenital lower eyelid retraction was performed on seven eyelids (36.8%). Ten eyelids (52.6%) exhibited secondary lower eyelid retraction after surgery. One eyelid (5.3%) was affected by facial palsy and one eyelid (5.3%) exhibited exophthalmos of an unknown origin. We adopted a selective approach based on lower eyelid retraction severity. Spacer grafting via a subconjunctival approach was the most commonly performed surgical technique (13 eyelids, 68.4%). The lateral tarsal strip procedure was used to horizontally tighten three eyelids (15.8%). At the time of the procedure, one of these eyelids (5.3%) also received an adjuvant suborbicularis oculi fat lift. Autogenous dermis fat grafting was performed on two lower eyelids (10.5%), whose retraction was caused by fat and soft tissue loss. Cosmetic outcomes were satisfactory in all cases. To achieve satisfactory surgical outcomes, surgeons should adopt an approach based on the severity of lower eyelid retraction. Mild lower eyelid retraction can be corrected without grafts. When retraction is severe and exceeds 2 mm, spacer grafts that push the lower eyelid margin upwards and support it from below are required. © 2017 The Korean Ophthalmological Society

Freiluftschulen: Eine Historisch-Padagogische Randerscheinung als Reflex Sozial-Historischer Modernisierungsprozesse? Das Beispiel Belgiens (Open-Air Schools: A Marginal Appearance in Pedagogical History as a Reflection of Socio-Historical Processes of Modernization? The Example of Belgium).

ERIC Educational Resources Information Center

Depaepe, Marc; Simon, Frank

2003-01-01

Discusses the history of open-air schools using an evaluation of Belgian schools. Expounds on the complex relationship between educational space and the educational act, and between traditional and progressive education. Demonstrates that open-air schools provided the same education as traditional schools and were not a real alternative for…

Do marginalized neighbourhoods have less healthy retail food environments? An analysis using Bayesian spatial latent factor and hurdle models.

PubMed

Luan, Hui; Minaker, Leia M; Law, Jane

2016-08-22

Findings of whether marginalized neighbourhoods have less healthy retail food environments (RFE) are mixed across countries, in part because inconsistent approaches have been used to characterize RFE 'healthfulness' and marginalization, and researchers have used non-spatial statistical methods to respond to this ultimately spatial issue. This study uses in-store features to categorize healthy and less healthy food outlets. Bayesian spatial hierarchical models are applied to explore the association between marginalization dimensions and RFE healthfulness (i.e., relative healthy food access that modelled via a probability distribution) at various geographical scales. Marginalization dimensions are derived from a spatial latent factor model. Zero-inflation occurring at the walkable-distance scale is accounted for with a spatial hurdle model. Neighbourhoods with higher residential instability, material deprivation, and population density are more likely to have access to healthy food outlets within a walkable distance from a binary 'have' or 'not have' access perspective. At the walkable distance scale however, materially deprived neighbourhoods are found to have less healthy RFE (lower relative healthy food access). Food intervention programs should be developed for striking the balance between healthy and less healthy food access in the study region as well as improving opportunities for residents to buy and consume foods consistent with dietary recommendations.

Safety of needle electromyography of the diaphragm: Anterior lung margins in quietly breathing healthy subjects.

PubMed

Podnar, Simon; Doorduin, Jonne

2016-06-01

Controversy persists as to whether the lung interposes on the needle electrode insertion path during diaphragm electromyography (EMG). Using high-resolution ultrasonography, we measured the distances between the medial recess of the intercostal spaces (ICSs) around the mid-clavicular line (MCL) and the lung margin. We performed measurements bilaterally during quiet breathing in the seated and supine positions. We studied 10 young healthy men and found that, in the first ICS with the medial recess clearly (i.e., several cm) lateral to MCL (usually the eighth ICS), the distance between the recommended insertion site and the lung margin varied from 7.5 to 17 cm. The distance was slightly larger on the right side and in the supine position. This study confirms that properly conducted "trans-intercostal" needle EMG of the diaphragm is generally safe in healthy subjects. Muscle Nerve 54: 54-57, 2016. © 2015 Wiley Periodicals, Inc.

Field Margins, Foraging Distances and Their Impacts on Nesting Pollinator Success

PubMed Central

Rands, Sean A.; Whitney, Heather M.

2011-01-01

The areas of wild land around the edges of agricultural fields are a vital resource for many species. These include insect pollinators, to whom field margins provide both nest sites and important resources (especially when adjacent crops are not in flower). Nesting pollinators travel relatively short distances from the nest to forage: most species of bee are known to travel less than two kilometres away. In order to ensure that these pollinators have sufficient areas of wild land within reach of their nests, agricultural landscapes need to be designed to accommodate the limited travelling distances of nesting pollinators. We used a spatially-explicit modelling approach to consider whether increasing the width of wild strips of land within the agricultural landscape will enhance the amount of wild resources available to a nesting pollinator, and if it would impact differently on pollinators with differing foraging strategies. This was done both by creating field structures with a randomised geography, and by using landscape data based upon the British agricultural landscape. These models demonstrate that enhancing field margins should lead to an increase in the availability of forage to pollinators that nest within the landscape. With the exception of species that only forage within a very short range of their nest (less than 125 m), a given amount of field margin manipulation should enhance the proportion of land available to a pollinator for foraging regardless of the distance over which it normally travels to find food. A fixed amount of field edge manipulation should therefore be equally beneficial for both longer-distance nesting foragers such as honeybees, and short-distance foragers such as solitary bees. PMID:21991390

Numerical Correlation of Levator Advancement in Preoperative Planning.

PubMed

Makeeva, Valeria; Collawn, Sherry S; Pierce, Evelina N; Mousa, Mina S; Yang, Jennifer H; Davison, Peter N; Jospitre, Elodie C

2017-06-01

Several procedures have been proposed for the treatment of eyelid ptosis, and both levator advancement and levator plication are widely used to shorten the levator palpebrae superioris. The purpose of this study was to quantify perioperative lid measurements in patients undergoing bilateral levator aponeurosis advancements to aid in preoperative planning. Between July 2014 and June 2016, the authors performed a retrospective analysis of all bilateral upper eyelid levator advancement procedures for ptosis performed by the senior surgeon. There are a total of 21 patients (6 men and 15 women) with a mean age of 63 years (range, 48-79 years). The average time at follow-up was 5.3 months, with a range of 1 to 26 months. In this retrospective study, we collected data on presurgical measurements including marginal reflex distance 1 (MRD1), surgical technique used (symmetrical/asymmetrical levator advancement) with millimeters of advancement used, and postsurgical measurements. We found that on average, an advancement of 4 mm led to an improvement in MRD1 of 2.26 mm (n = 14), and advancement of 5 mm led to an improvement in MRD1 of 2.74 mm (n = 15). Patients also reported improvements in their quality of life. Our results may be used to guide clinicians in preoperative planning.

Role of specimen US for predicting resection margin status in breast conserving therapy.

PubMed

Moschetta, M; Telegrafo, M; Introna, T; Coi, L; Rella, L; Ranieri, V; Cirili, A; Stabile Ianora, A A; Angelelli, G

2015-01-01

To assess the diagnostic accuracy of specimen ultrasound (US) for predicting resection margin status in women undergoing breast conserving therapy for US-detected cancer, having the histological findings as the reference standard. A total of 132 consecutive patients (age range, 34-87 years; mean, 51 years) underwent breast-conserving surgery for US-detected invasive breast cancer. All surgical specimens underwent US examination. The presence of lesion within the specimen and its distance from the specimen margins were assessed considering a threshold distance between the lesion and specimen margins of 10 mm. US findings were then compared with the pathological ones and specimen US. Sensitivity, specificity, diagnostic accuracy, positive (PPV) and negative predictive values (NPV) for predicting histological margin status were evaluated, having the histological findings as the reference standard. The histological examination detected invasive ductal carcinoma in 96/132 (73%) cases, invasive lobular carcinoma in 32/132 (24%), mucinous carcinoma in 4/132 (3%). The pathological margin analysis revealed 96/132 (73%) negative margins and 36 (27%) close/positive margins. US examination detected all 132 breast lesions within the surgical specimens. 110 (83%) negative margins and 22 (17%) positive margins were found on US. Sensitivity, specificity, diagnostic accuracy, PPV and NPV of 44%, 94%, 80%, 73% and 82%, respectively, were found for specimen US. Specimen US represents a time and cost saving imaging tool for evaluating the presence of US detected-breast lesion within surgical specimen and for predicting the histological margin status.

Design, development and validation of a new laryngo-pharyngeal endoscopic esthesiometer and range-finder based on the assessment of air-pulse variability determinants.

PubMed

Giraldo-Cadavid, Luis F; Agudelo-Otalora, Luis Mauricio; Burguete, Javier; Arbulu, Mario; Moscoso, William Daniel; Martínez, Fabio; Ortiz, Andrés Felipe; Diaz, Juan; Pantoja, Jaime A; Rueda-Arango, Andrés Felipe; Fernández, Secundino

2016-05-10

Laryngo-pharyngeal mechano-sensitivity (LPMS) is involved in dysphagia, sleep apnea, stroke, irritable larynx syndrome and cough hypersensitivity syndrome among other disorders. These conditions are associated with a wide range of airway reflex abnormalities. However, the current device for exploring LPMS is limited because it assesses only the laryngeal adductor reflex during fiber-optic endoscopic evaluations of swallowing and requires a high degree of expertise to obtain reliable results, introducing intrinsic expert variability and subjectivity. We designed, developed and validated a new air-pulse laryngo-pharyngeal endoscopic esthesiometer with a built-in laser range-finder (LPEER) based on the evaluation and control of air-pulse variability determinants and on intrinsic observer variability and subjectivity determinants of the distance, angle and site of stimulus impact. The LPEER was designed to be capable of delivering precise and accurate stimuli with a wide range of intensities that can explore most laryngo-pharyngeal reflexes. We initially explored the potential factors affecting the reliability of LPMS tests and included these factors in a multiple linear regression model. The following factors significantly affected the precision and accuracy of the test (P < 0.001): the tube conducting the air-pulses, the supply pressure of the system, the duration of the air-pulses, and the distance and angle between the end of the tube conducting the air-pulses and the site of impact. To control all of these factors, an LPEER consisting of an air-pulse generator and an endoscopic laser range-finder was designed and manufactured. We assessed the precision and accuracy of the LPEER's stimulus and range-finder according to the coefficient of variation (CV) and by looking at the differences between the measured properties and the desired values, and we performed a pilot validation on ten human subjects. The air-pulses and range-finder exhibited good precision and accuracy (CV < 0.06), with differences between the desired and measured properties at <3 % and a range-finder measurement error of <1 mm. The tests in patients demonstrated obtainable and reproducible thresholds for the laryngeal adductor, cough and gag reflexes. The new LPEER was capable of delivering precise and accurate stimuli for exploring laryngo-pharyngeal reflexes.

Effects of Low Intensity Microwave Radiation on Mammalian Serum Components.

DTIC Science & Technology

1977-10-01

34animal hypnosis ", has been described in detail by Klemm 3. Rabbits are inverted and placed on their backs in a box consisting of a base and two sides...depresa:ant, was injected into the marginal ear vein of the rabbit during a 2 minute period, producing a rapid onset of anesthesia charac- terized by...immediately prior to anesthesia and again 15 to 30 seconds after the righting reflex was regained and the microwave power was _ turned off; total

Acculturative Stress and Depressive Symptomatology among Mexican and Mexican American Students in the U.S.: Examining Associations with Cultural Incongruity and Intragroup Marginalization

ERIC Educational Resources Information Center

Cano, Miguel Ángel; Castillo, Linda G.; Castro, Yessenia; de Dios, Marcel A.; Roncancio, Angelica M.

2014-01-01

This study examined associations of intragroup marginalization and cultural incongruity with acculturative stress and depressive symptoms among 155 undergraduate U.S. college students of Mexican heritage. Findings indicate that perceived interpersonal distancing by the family (intragroup marginalization) and perceived lack of cultural fit between…

The relation between bystanders’ behavioral reactivity to distress and later helping behavior during a violent conflict in virtual reality

PubMed Central

Neyret, Solène; Slater, Mel; de Gelder, Beatrice

2018-01-01

The occurrence of helping behavior is thought to be automatically triggered by reflexive reactions and promoted by intuitive decisions. Here, we studied whether reflexive reactions to an emergency situation are associated with later helping behavior in a different situation, a violent conflict. First, 29 male supporters of F.C. Barcelona performed a cued-reaction time task with a low and high cognitive load manipulation, to tap into reflexive and reflective processes respectively, during the observation of an emergency. Next, participants entered a bar in Virtual Reality and had a conversation with a virtual fellow supporter. During this conversation, a virtual Real Madrid supporter entered and started an aggressive argument with the fellow supporter that escalated into a physical fight. Verbal and physical interventions of the participant served as measures of helping behavior. Results showed that faster responses to an emergency situation during low, but not during high cognitive load, were associated with more interventions during the violent conflict. However, a tendency to describe the decision to act during the violent conflict as intuitive and reflex-like was related to more interventions. Further analyses revealed that a disposition to experience sympathy, other-oriented feelings during distressful situations, was related to self-reported intuitive decision-making, a reduced distance to the perpetrator, and higher in the intervening participants. Taken together, these results shed new light on helping behavior and are consistent with the notion of a motivational system in which the act of helping is dependent on a complex interplay between intuitive, reflexive and deliberate, reflective processes. PMID:29672638

The relation between bystanders' behavioral reactivity to distress and later helping behavior during a violent conflict in virtual reality.

PubMed

Hortensius, Ruud; Neyret, Solène; Slater, Mel; de Gelder, Beatrice

2018-01-01

The occurrence of helping behavior is thought to be automatically triggered by reflexive reactions and promoted by intuitive decisions. Here, we studied whether reflexive reactions to an emergency situation are associated with later helping behavior in a different situation, a violent conflict. First, 29 male supporters of F.C. Barcelona performed a cued-reaction time task with a low and high cognitive load manipulation, to tap into reflexive and reflective processes respectively, during the observation of an emergency. Next, participants entered a bar in Virtual Reality and had a conversation with a virtual fellow supporter. During this conversation, a virtual Real Madrid supporter entered and started an aggressive argument with the fellow supporter that escalated into a physical fight. Verbal and physical interventions of the participant served as measures of helping behavior. Results showed that faster responses to an emergency situation during low, but not during high cognitive load, were associated with more interventions during the violent conflict. However, a tendency to describe the decision to act during the violent conflict as intuitive and reflex-like was related to more interventions. Further analyses revealed that a disposition to experience sympathy, other-oriented feelings during distressful situations, was related to self-reported intuitive decision-making, a reduced distance to the perpetrator, and higher in the intervening participants. Taken together, these results shed new light on helping behavior and are consistent with the notion of a motivational system in which the act of helping is dependent on a complex interplay between intuitive, reflexive and deliberate, reflective processes.

Probe-based confocal laser endomicroscopy in the margin delineation of early gastric cancer for endoscopic submucosal dissection.

PubMed

Park, Jun Chul; Park, Yehyun; Kim, Hyun Ki; Jo, Jeong-Hyeon; Park, Chan Hyuk; Kim, Eun Hye; Jung, Da Hyun; Chung, Hyunsoo; Shin, Sung Kwan; Lee, Sang Kil; Lee, Yong Chan

2017-05-01

We evaluated probe-based confocal laser endomicroscopy (pCLE) in the margin delineation of early gastric cancer (EGC) for endoscopic submucosal dissection in comparison with white-light imaging with chromoendoscopy (CE). We conducted a prospective, randomized controlled study from November 2013 to October 2014 in a tertiary referral hospital. A total of 101 patients scheduled for endoscopic submucosal dissection due to differentiated EGC were randomized into pCLE and CE groups (pCLE 51, CE 50). Markings were made by electrocautery at the proximal and distal tumor margins, as determined by either pCLE or CE. The distance from the marking to the tumor margin was measured in the resected specimen histopathologically and was compared between the two groups by a linear mixed model. Among 104 lesions, 80 lesions with 149 markings (pCLE 68, CE 81) were analyzed after excluding undifferentiated EGCs (n = 8) and unidentifiable markings (n = 13). Although the complete resection rate showed no difference between the groups (94.6% vs 93.2%, P = 1.000), the median distance from the marking to the margin was shorter in the pCLE group (1.3 vs 1.8 mm, P = 0.525) and the proportion of the distance <1 mm was higher (43.9% vs 27.6%, P = 0.023) in the pCLE group. Finally, subgroup analysis with superficial flat lesions (18 lesions, 31 marking dots) showed a significantly decreased distance in the pCLE group (0.5 vs 3.1 mm, P = 0.007). Among EGCs with superficial flat morphology, in which the accurate evaluation of lateral extent is difficult with CE, pCLE would be useful for more precise margin delineation. © 2016 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Role of specimen US for predicting resection margin status in breast conserving therapy

PubMed Central

MOSCHETTA, M.; TELEGRAFO, M.; INTRONA, T.; COI, L.; RELLA, L.; RANIERI, V.; CIRILLI, A.; IANORA, A.A. STABILE; ANGELELLI, G.

2015-01-01

Aim To assess the diagnostic accuracy of specimen ultrasound (US) for predicting resection margin status in women undergoing breast conserving therapy for US-detected cancer, having the histological findings as the reference standard. Patients and methods A total of 132 consecutive patients (age range, 34–87 years; mean, 51 years) underwent breast-conserving surgery for US-detected invasive breast cancer. All surgical specimens underwent US examination. The presence of lesion within the specimen and its distance from the specimen margins were assessed considering a threshold distance between the lesion and specimen margins of 10 mm. US findings were then compared with the pathological ones and specimen US. Sensitivity, specificity, diagnostic accuracy, positive (PPV) and negative predictive values (NPV) for predicting histological margin status were evaluated, having the histological findings as the reference standard. Results The histological examination detected invasive ductal carcinoma in 96/132 (73%) cases, invasive lobular carcinoma in 32/132 (24%), mucinous carcinoma in 4/132 (3%). The pathological margin analysis revealed 96/132 (73%) negative margins and 36 (27%) close/positive margins. US examination detected all 132 breast lesions within the surgical specimens. 110 (83%) negative margins and 22 (17%) positive margins were found on US. Sensitivity, specificity, diagnostic accuracy, PPV and NPV of 44%, 94%, 80%, 73% and 82%, respectively, were found for specimen US. Conclusions Specimen US represents a time and cost saving imaging tool for evaluating the presence of US detected-breast lesion within surgical specimen and for predicting the histological margin status. PMID:26712255

Brainstem response patterns in deeply-sedated critically-ill patients predict 28-day mortality.

PubMed

Rohaut, Benjamin; Porcher, Raphael; Hissem, Tarik; Heming, Nicholas; Chillet, Patrick; Djedaini, Kamel; Moneger, Guy; Kandelman, Stanislas; Allary, Jeremy; Cariou, Alain; Sonneville, Romain; Polito, Andréa; Antona, Marion; Azabou, Eric; Annane, Djillali; Siami, Shidasp; Chrétien, Fabrice; Mantz, Jean; Sharshar, Tarek

2017-01-01

Deep sedation is associated with acute brain dysfunction and increased mortality. We had previously shown that early-assessed brainstem reflexes may predict outcome in deeply sedated patients. The primary objective was to determine whether patterns of brainstem reflexes might predict mortality in deeply sedated patients. The secondary objective was to generate a score predicting mortality in these patients. Observational prospective multicenter cohort study of 148 non-brain injured deeply sedated patients, defined by a Richmond Assessment sedation Scale (RASS) <-3. Brainstem reflexes and Glasgow Coma Scale were assessed within 24 hours of sedation and categorized using latent class analysis. The Full Outline Of Unresponsiveness score (FOUR) was also assessed. Primary outcome measure was 28-day mortality. A "Brainstem Responses Assessment Sedation Score" (BRASS) was generated. Two distinct sub-phenotypes referred as homogeneous and heterogeneous brainstem reactivity were identified (accounting for respectively 54.6% and 45.4% of patients). Homogeneous brainstem reactivity was characterized by preserved reactivity to nociceptive stimuli and a partial and topographically homogenous depression of brainstem reflexes. Heterogeneous brainstem reactivity was characterized by a loss of reactivity to nociceptive stimuli associated with heterogeneous brainstem reflexes depression. Heterogeneous sub-phenotype was a predictor of increased risk of 28-day mortality after adjustment to Simplified Acute Physiology Score-II (SAPS-II) and RASS (Odds Ratio [95% confidence interval] = 6.44 [2.63-15.8]; p<0.0001) or Sequential Organ Failure Assessment (SOFA) and RASS (OR [95%CI] = 5.02 [2.01-12.5]; p = 0.0005). The BRASS (and marginally the FOUR) predicted 28-day mortality (c-index [95%CI] = 0.69 [0.54-0.84] and 0.65 [0.49-0.80] respectively). In this prospective cohort study, around half of all deeply sedated critically ill patients displayed an early particular neurological sub-phenotype predicting 28-day mortality, which may reflect a dysfunction of the brainstem.

First images of the crustal structure across the eastern Algerian margin, from deep penetrating seismic data.

NASA Astrophysics Data System (ADS)

Bouyahiaoui, Boualem; Abtout, Abdeslam; Sage, Françoise; Klingelhoeffer, Frauke; Collot, Jean-yves; Yelles-chaouche, Abdelkarim; Marok, Abbas; Djellit, Hamou; Galves, Audrey; Bracène, Rabah; Schnurle, Philippe; Graindorge, David; party, Scientific

2013-04-01

The Algerian continental margin North Africa presents one of only a few examples of a passive continental margin formed in a back-arc environment, which undergoes current compression and is proposed to be reactivated today. In the framework of the Algerian - French SPIRAL research program (Sismique Profonde et Investigation Regionale du nord de l'ALgérie), a seismic cruise was conducted on the R/V Atalante from September to November 2009. During the cruise, deep penetrating low frequency multichannel and wide-angle seismic data were acquired in order to study the deep structure of the Algerian margin. In this work, we present the preliminary results from wide-angle modeling of the North-east Algerian margin in the region of Annaba along a N-S transect using a data set of 42 OBS (ocean bottom seismometers) along a profile extending 117km, and 13 broadband seismological stations along a profile of 80 km length. Travel-time tomography and forward modeling were undertaken to model the velocity structure in this region. The resulting velocity models image the thickness of the sedimentary layers, which varies between a few hundred meters on the continental margin of more than 4 km in the basin. The crust is about 6 km thick in the basin, and thickens to 7-8 km between 40 and 60km distance from the margin toe. Crustal thickness increases to about 22 km at the continental slope over a distance of ~ 90 km. The nature of the crust was determined to be thin oceanic with abnormal velocity gradient in the basin, and thinned continental from around 30 km distance from the coast landward. Integration of the wide-angle seismic data with multichannel seismic, gravity and magnetic data will help to better understand the structure of the Algerian margin and the adjacent oceanic basin in the Annaba region, and to discuss the numerous cinematic models proposed in literature regarding the formation of the north-Algerian basin.

Flexible strategies for flight control: an active role for the abdomen.

PubMed

Dyhr, Jonathan P; Morgansen, Kristi A; Daniel, Thomas L; Cowan, Noah J

2013-05-01

Moving animals orchestrate myriad motor systems in response to multimodal sensory inputs. Coordinating movement is particularly challenging in flight control, where animals deal with potential instability and multiple degrees of freedom of movement. Prior studies have focused on wings as the primary flight control structures, for which changes in angle of attack or shape are used to modulate lift and drag forces. However, other actuators that may impact flight performance are reflexively activated during flight. We investigated the visual-abdominal reflex displayed by the hawkmoth Manduca sexta to determine its role in flight control. We measured the open-loop stimulus-response characteristics (measured as a transfer function) between the visual stimulus and abdominal response in tethered moths. The transfer function reveals a 41 ms delay and a high-pass filter behavior with a pass band starting at ~0.5 Hz. We also developed a simplified mathematical model of hovering flight wherein articulation of the thoracic-abdominal joint redirects an average lift force provided by the wings. We show that control of the joint, subject to a high-pass filter, is sufficient to maintain stable hovering, but with a slim stability margin. Our experiments and models suggest a novel mechanism by which articulation of the body or 'airframe' of an animal can be used to redirect lift forces for effective flight control. Furthermore, the small stability margin may increase flight agility by easing the transition from stable flight to a more maneuverable, unstable regime.

Vestibular evoked myogenic potentials (VEMPs) in central neurological disorders.

PubMed

Venhovens, J; Meulstee, J; Verhagen, W I M

2016-01-01

Several types of acoustic stimulation (i.e. tone bursts or clicks), bone-conducted vibration, forehead taps, and galvanic stimulation elicit myogenic potentials. These can be recorded in cervical and ocular muscles, the so called vestibular evoked myogenic potentials (VEMPs). The cervical VEMP (cVEMP) resembles the vestibulo-collic reflex and the responses can be recorded from the ipsilateral sternocleidomastoid muscle. The ocular VEMP resembles the vestibulo-ocular reflex and can be recorded from extra-ocular muscles by a surface electrode beneath the contralateral infraorbital margin. Initially, the literature concerning VEMPs was limited to peripheral vestibular disorders, however, the field of VEMP testing is rapidly expanding, with an increasing focus on central neurological disorders. The current literature concerning VEMP abnormalities in central neurological disorders is critically reviewed, especially regarding the methodological aspects in relation to quality as well as the clinical interpretation of the VEMP results. Suggestions for further research are proposed as well as some clinically useful indications. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Impact of Target Distance, Target Size, and Visual Acuity on the Video Head Impulse Test.

PubMed

Judge, Paul D; Rodriguez, Amanda I; Barin, Kamran; Janky, Kristen L

2018-05-01

The video head impulse test (vHIT) assesses the vestibulo-ocular reflex. Few have evaluated whether environmental factors or visual acuity influence the vHIT. The purpose of this study was to evaluate the influence of target distance, target size, and visual acuity on vHIT outcomes. Thirty-eight normal controls and 8 subjects with vestibular loss (VL) participated. vHIT was completed at 3 distances and with 3 target sizes. Normal controls were subdivided on the basis of visual acuity. Corrective saccade frequency, corrective saccade amplitude, and gain were tabulated. In the normal control group, there were no significant effects of target size or visual acuity for any vHIT outcome parameters; however, gain increased as target distance decreased. The VL group demonstrated higher corrective saccade frequency and amplitude and lower gain as compared with controls. In conclusion, decreasing target distance increases gain for normal controls but not subjects with VL. Preliminarily, visual acuity does not affect vHIT outcomes.

Intra-fraction motion of larynx radiotherapy

NASA Astrophysics Data System (ADS)

Durmus, Ismail Faruk; Tas, Bora

2018-02-01

In early stage laryngeal radiotherapy, movement is an important factor. Thyroid cartilage can move from swallowing, breathing, sound and reflexes. The effects of this motion on the target volume (PTV) during treatment were examined. In our study, the target volume movement during the treatment for this purpose was examined. Thus, setup margins are re-evaluated and patient-based PTV margins are determined. Intrafraction CBCT was scanned in 246 fractions for 14 patients. During the treatment, the amount of deviation which could be lateral, vertical and longitudinal axis was determined. ≤ ± 0.1cm deviation; 237 fractions in the lateral direction, 202 fractions in the longitudinal direction, 185 fractions in the vertical direction. The maximum deviation values were found in the longitudinal direction. Intrafraction guide in laryngeal radiotherapy; we are sure of the correctness of the treatment, the target volume is to adjust the margin and dose more precisely, we control the maximum deviation of the target volume for each fraction. Although the image quality of intrafraction-CBCT scans was lower than the image quality of planning CT, they showed sufficient contrast for this work.

One-millimeter cancer-free margin is curative for colorectal liver metastases: a propensity score case-match approach.

PubMed

Hamady, Zaed Z R; Lodge, J Peter A; Welsh, Fenella K; Toogood, Giles J; White, Alan; John, Timothy; Rees, Myrddin

2014-03-01

To investigate the influence of clear surgical resection margin width on disease recurrence rate after intentionally curative resection of colorectal liver metastases. There is consensus that a histological positive resection margin is a predictor of disease recurrence after resection of colorectal liver metastases. The dispute, however, over the width of cancer-free resection margin required is ongoing. Analysis of observational prospectively collected data for 2715 patients who underwent primary resection of colorectal liver metastases from 2 major hepatobiliary units in the United Kingdom. Histological cancer-free resection margin was classified as positive (if cancer cells present at less than 1 mm from the resection margin) or negative (if the distance between the cancer and the margin is 1 mm or more). The negative margin was further classified according to the distance from the tumor in millimeters. Predictors of disease-free survival were analyzed in univariate and multivariate analyses. A case-match analysis by a propensity score method was undertaken to reduce bias. A 1-mm cancer-free resection margin was sufficient to achieve 33% 5-year overall disease-free survival. Extra margin width did not add disease-free survival advantage (P > 0.05). After the propensity case-match analysis, there is no statistical difference in disease-free survival between patients with negative narrow and wider margin clearance [hazard ratio (HR) 1.0; 95% (confidence interval) CI: 0.9-1.2; P = 0.579 at 5-mm cutoff and HR 1.1; 95% CI: 0.96-1.3; P = 0.149 at 10-mm cutoff]. Patients with extrahepatic disease and positive lymph node primary tumor did not have disease-free survival advantage despite surgical margin clearance (9 months for <1-mm vs 12 months for ≥1-mm margin clearance; P = 0.062). One-mm cancer-free resection margin achieved in patients with colorectal liver metastases should now be considered the standard of care.

Outcomes of levator resection at tertiary eye care center in Iran: a 10-year experience.

PubMed

Abrishami, Alireza; Bagheri, Abbas; Salour, Hossein; Aletaha, Maryam; Yazdani, Shahin

2012-02-01

To assess outcomes of levator resection for the surgical correction of congenital and acquired upper lid ptosis in patients with fair to good levator function and evaluation of the relationship between demographic data and success of this operation. In a retrospective study, medical records of patients with blepharoptosis who had undergone levator resection over a 10-year period and were followed for at least 3 months were reviewed. Overall, 136 patients including 60 (44.1%) male and 76 (55.9%) female subjects with a mean age of 20 ± 13.8 years (range, 2 to 80 years) were evaluated, of whom 120 cases (88.2%) had congenital ptosis and the rest had acquired ptosis. The overall success rate after the first operation was 78.7%. The most common complication after the first operation was undercorrection in 26 cases (19.1%), which was more prevalent among young patients (p = 0.06). Lid fissure and margin reflex distance (MRD(1)) also increased after levator resection (p < 0.001). Age, sex, type of ptosis, amblyopia, levator function, MRD(1), lid fissure and spherical equivalent were not predictive of surgical outcomes of levator resection. Levator resection has a high rate of success and few complications in the surgical treatment of congenital and acquired upper lid ptosis with fair to good levator function. Reoperation can be effective in most cases in which levator resection has been performed.

SU-E-T-36: An Investigation of the Margin From CTV to PTV Using Retraction Method for Cervical Carcinoma

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

Wu, D; Chen, J; Hao, Y

Purpose: This work employs the retraction method to compute and evaluate the margin from CTV to PTV based on the influence of target dosimetry of setup errors during cervical carcinoma patients treatment. Methods: Sixteen patients with cervical cancer were treated by Elekta synergy and received a total of 305 KV-CBCT images. The iso-center of the initial plans were changed according to the setup errors to simulate radiotherapy and then recalculated the dose distribution using leaf sequences and MUs for individual plans. The margin from CTV to PTV will be concluded both by the method of retracting (Fixed the PTV ofmore » the original plan, and retract PTV a certain distance defined as simulative organization CTVnx. The minimum distance value from PTV to CTVnx which get specified doses, namely guarantee at least 99% CTV volume can receive the dose of 95%, is the margin CTV to PTV we found) and the former formula method. Results: (1)The setup errors of 16 patients in X, Y and Z directions were(1.13±2.94) mm,(−1.63±7.13) mm,(−0.65±2.25) mm. (2) The distance between CTVx and PTV was 5, 9 and 3mm in X, Y and Z directions According to 2.5+0.7σ. (3) Transplantation plans displayed 99% of CTVx10- CTVx7 and received 95% of prescription dose, but CTVx6- CTVx3 departed from standard of clinic.In order to protect normal tissues, we selected 7mm as the minimum value of the margin from CTV to PTV. Conclusion: We have test an retraction method for the margin from CTV to PTV evaluation. The retraction method is more reliable than the formula method for calculating the margin from the CTV to the PTV, because it represented practice of treatment, and increasing a new method in this field.« less

Margins within Margins?: Voices Speaking through a Study of the Provision of an Educational Program for the Children of One Australian Show Circuit.

ERIC Educational Resources Information Center

Rose, C. G.; And Others

This paper examines the tactics used by the Showmen's Guild of Australasia in successfully lobbying for the development of a distance education program for their children. The Guild is considered to be a "marginalized" group, meaning members have less access to wealth, power, and status. Since 1930, members of the Showmen's Guild and…

On the Margins or at the Center? Distance Education in Higher Education

ERIC Educational Resources Information Center

Xiao, Junhong

2018-01-01

This reflection focuses on the position of distance education in today's global higher education. Firstly, it identifies three types of convergence of distance and campus-based education--dual mode, add-on/blended, and full convergence--arguing that the last type has yet to be fully realized due to the complexities involved. It then critiques the…

MO-FG-CAMPUS-JeP3-01: A Statistical Model for Analyzing the Rotational Error of Single Iso-Center Technique

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

Chang, J; Dept of Radiation Oncology, New York Weill Cornell Medical Ctr, New York, NY

Purpose: To develop a generalized statistical model that incorporates the treatment uncertainty from the rotational error of single iso-center technique, and calculate the additional PTV (planning target volume) margin required to compensate for this error. Methods: The random vectors for setup and additional rotation errors in the three-dimensional (3D) patient coordinate system were assumed to follow the 3D independent normal distribution with zero mean, and standard deviations σx, σy, σz, for setup error and a uniform σR for rotational error. Both random vectors were summed, normalized and transformed to the spherical coordinates to derive the chi distribution with 3 degreesmore » of freedom for the radical distance ρ. PTV margin was determined using the critical value of this distribution for 0.05 significant level so that 95% of the time the treatment target would be covered by ρ. The additional PTV margin required to compensate for the rotational error was calculated as a function of σx, σy, σz and σR. Results: The effect of the rotational error is more pronounced for treatments that requires high accuracy/precision like stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT). With a uniform 2mm PTV margin (or σx =σy=σz=0.7mm), a σR=0.32mm will decrease the PTV coverage from 95% to 90% of the time, or an additional 0.2mm PTV margin is needed to prevent this loss of coverage. If we choose 0.2 mm as the threshold, any σR>0.3mm will lead to an additional PTV margin that cannot be ignored, and the maximal σR that can be ignored is 0.0064 rad (or 0.37°) for iso-to-target distance=5cm, or 0.0032 rad (or 0.18°) for iso-to-target distance=10cm. Conclusions: The rotational error cannot be ignored for high-accuracy/-precision treatments like SRS/SBRT, particularly when the distance between the iso-center and target is large.« less

(De)colonizing culture in community psychology: reflections from critical social science.

PubMed

Reyes Cruz, Mariolga; Sonn, Christopher C

2011-03-01

Since its inception, community psychology has been interested in cultural matters relating to issues of diversity and marginalization. However, the field has tended to understand culture as static social markers or as the background for understanding group differences. In this article the authors contend that culture is inseparable from who we are and what we do as social beings. Moreover, culture is continually shaped by socio-historical and political processes intertwined within the globalized history of power. The authors propose a decolonizing standpoint grounded in critical social science to disrupt understandings of cultural matters that marginalize others. This standpoint would move the field toward deeper critical thinking, reflexivity and emancipatory action. The authors present their work to illustrate how they integrate a decolonizing standpoint to community psychology research and teaching. They conclude that community psychology must aim towards intercultural work engaging its political nature from a place of ontological/epistemological/methodological parity.

Movement of the projected pedicles relative to the projected vertebral body in a fourth lumbar vertebra during axial rotation.

PubMed

Coleman, Roger R; Thomas, I Walker

2004-01-01

One use of the anteroposterior lumbar radiograph is to determine axial (y-axis) rotation of the lumbar vertebrae. Rotation might be an element of interest to clinicians seeking to evaluate vertebral positioning. Correlate and quantify movements of the projected pedicles relative to the projected vertebral body during axial rotation and determine if vertebral asymmetry and changes in object film distance affect these movements. A three-dimensional computer model of the fourth and fifth lumbar vertebrae, a modeled radiograph source, and a modeled film were produced. The vertebral model was placed in various degrees of axial rotation at a number of different object film distances. Lines from the source were passed through the pedicles of the fourth lumbar vertebral model and additional lines erected tangent to the lateral body margins. These lines were extended to points of contact with the modeled film. The projected pedicles move relative to the projected vertebral body during y-axis rotation. Vertebral asymmetry and object film distances can also affect the distance of the projected pedicle relative to the projected lateral body margin. Axial rotation produces movement of the projected pedicles relative to the projected vertebral body. However, vertebral asymmetry and changes in object film distance also affect the position of the projected pedicles relative to the projected lateral body margin and might serve as confounders to the clinician seeking to analyze vertebral rotation through the use of the projected pedicles.

The stability of M(max) and H (max) amplitude over time.

PubMed

McNulty, Penelope A; Shiner, Christine T; Thayaparan, Ganesha K; Burke, David

2012-05-01

The stability of the maximal muscle response (M(max)) is critical to H reflex methodology. It has previously been reported that the amplitude of M(max) declines over time. If reproducible, this finding would have implications for all experimental studies that normalise the output of the motoneurone pool against the M wave. We investigated the effect of time on changes in M(max) and the maximal H reflex (H(max)) evoked at 4-s intervals over 60 min. To identify an influence of homosynaptic depression, we extended the interstimulus interval to 10 s and the time to 100 min. Two recording montages over soleus were used to ensure that interelectrode distance was not a critical factor. The soleus M(max) and H reflex were evoked by stimulation of the tibial nerve in the popliteal fossa in 7 subjects who sat with the knee flexed to 30° and the ankle plantar flexed by ~30°. We found no change in the pooled data for M(max), H(max), a reflex 50% of maximal, or the current required to produce it. However, one subject had a statistically significant increase in M(max) and a concurrent decrease in H(max) regardless of the interstimulus interval. On average, there was no change in the H(max)/M(max) ratio over time. While both M(max) and H(max) may change in response to many factors, these results suggest that, typically, time is not one of them.

Advanced Techniques for Assessment of Postural and Locomotor Ataxia, Spatial Orientation, and Gaze Stability

NASA Technical Reports Server (NTRS)

Wall, Conrad., III

1999-01-01

In addition to adapting to microgravity, major neurovestibular problems of space flight include postflight difficulties with standing, walking, turning corners, and other activities that require stable upright posture and gaze stability. These difficulties inhibit astronauts' ability to stand or escape from their vehicle during emergencies. The long-ter7n goal of the NSBRI is the development of countermeasures to ameliorate the effects of long duration space flight. These countermeasures must be tested with valid and reliable tools. This project aims to develop quantitative, parametric approaches for assessing gaze stability and spatial orientation during normal gait and when gait is perturbed. Two of this year's most important findings concern head fixation distance and ideal trajectory analysis. During a normal cycle of walking the head moves up and down linearly. A simultaneous angular pitching motion of the head keeps it aligned toward an imaginary point in space at a distance of about one meter in front of a subject and along the line of march. This distance is called the head fixation distance. Head fixation distance provides the fundamental framework necessary for understanding the functional significance of the vestibular reflexes that couple head motion to eye motion. This framework facilitates the intelligent design of counter-measures for the effects of exposure to microgravity upon the vestibular ocular reflexes. Ideal trajectory analysis is a simple candidate countermeasure based upon quantifying body sway during repeated up and down stair stepping. It provides one number that estimates the body sway deviation from an ideal sinusoidal body sway trajectory normalized on the subject's height. This concept has been developed with NSBRI funding in less than one year. These findings are explained in more detail below. Compared to assessments of the vestibuo-ocular reflex, analysis of vestibular effects on locomotor function is relatively less well developed and quantified. We are improving this situation by applying methodologies such as nonlinear orbital stability to quantify responses and by using multivariate statistical approaches to link together the responses across separate tests. In this way we can exploit the information available and increase the ability to discriminate between normal and pathological responses. Measures of stability and orientation are compared to measures such as dynamic visual acuity and with balance function tests. The responses of normal human subjects and of patients having well documented pathophysiologies are being characterized. When these studies are completed, we should have a clearer idea about normal and abnormal patterns of eye, head, and body movements during locomotion and their stability in a wide range of environments. We plan eventually to use this information to validate the efficacy of candidate neurovestibular and neuromuscular rehabilitative techniques. Some representative studies made during this year are summarized.

An Astrometric Analysis of eta Carinae’s Eruptive History Using HST WF/PC2 and ACS Observations

DTIC Science & Technology

2007-07-11

Std Z39-18 to address the question of binarity. Based on an astrometric analysis of the data, binary reflex motion is detected in the primary and, by...Measurement Results 96 5.1 Primary Luminosity and Mass . . . . . . . . . . . . . . . . . . . . . . 96 5.2 Secondary Mass and Luminosity...Binary Models . . . . . . . . . . . 100 5.5 Primary –Secondary Distance . . . . . . . . . . . . . . . . . . . . . . . 102 5.6 Periastron passage

Biologically-inspired adaptive obstacle negotiation behavior of hexapod robots

PubMed Central

Goldschmidt, Dennis; Wörgötter, Florentin; Manoonpong, Poramate

2014-01-01

Neurobiological studies have shown that insects are able to adapt leg movements and posture for obstacle negotiation in changing environments. Moreover, the distance to an obstacle where an insect begins to climb is found to be a major parameter for successful obstacle negotiation. Inspired by these findings, we present an adaptive neural control mechanism for obstacle negotiation behavior in hexapod robots. It combines locomotion control, backbone joint control, local leg reflexes, and neural learning. While the first three components generate locomotion including walking and climbing, the neural learning mechanism allows the robot to adapt its behavior for obstacle negotiation with respect to changing conditions, e.g., variable obstacle heights and different walking gaits. By successfully learning the association of an early, predictive signal (conditioned stimulus, CS) and a late, reflex signal (unconditioned stimulus, UCS), both provided by ultrasonic sensors at the front of the robot, the robot can autonomously find an appropriate distance from an obstacle to initiate climbing. The adaptive neural control was developed and tested first on a physical robot simulation, and was then successfully transferred to a real hexapod robot, called AMOS II. The results show that the robot can efficiently negotiate obstacles with a height up to 85% of the robot's leg length in simulation and 75% in a real environment. PMID:24523694

Peri-implant soft tissue and marginal bone adaptation on implant with non-matching healing abutments: micro-CT analysis.

PubMed

Finelle, Gary; Papadimitriou, Dimitrios E V; Souza, André B; Katebi, Negin; Gallucci, German O; Araújo, Mauricio G

2015-04-01

To assess (i) the outcome of changing the horizontal-offset dimension on the peri-implant soft tissues and the crestal bone and (ii) the effect of different healing abutments (flared vs. straight) on the marginal peri-implant soft tissues and crestal bone. Two-piece dental implants diameters of 3.5 and 4.5 mm were placed at least 1 mm subcrestal in five beagle dogs. Three different investigational groups: (i) 3.5-mm-diameter implant with narrow healing abutment (3.5N), (ii) 4.5-mm-diameter implant with narrow healing abutment (4.5N), and (iii) 3.5-mm-diameter implant with wide healing abutment (3.5W), were assessed. After 4 months of healing, the vertical distance from the marginal crestal bone (MB) to the implant shoulder (IS); the vertical distance from the IS to the first bone-to-implant contact; and the horizontal distance of bone ingrowth on the implant platform were measured with a high-resolution micro-CT (Xradia MicroXCT-200 system). Implants with a narrow healing caps showed an interproximal MB located between 0 and 1 mm above the implant shoulder, while the 3.5W group exhibits a mean value -0.50 mm. As all implants in group 3.5N presented a fBIC located at the level of the IS. For the 4.5N group, the mean fBIC-IS distance was -0.52 mm apically to the IS. For the 3.5WC group, the mean fBIC-IS distance was -1.42 mm. Horizontal bone apposition was only observed for the 3.5N group and the 4.5N group. The dimension of the horizontal offset would play a minimal role in reducing bone remodeling, whereas the configuration of the transmucosal component would directly influence marginal bone remodeling. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Early Oral Tongue Squamous Cell Carcinoma: Sampling of Margins From Tumor Bed and Worse Local Control.

PubMed

Maxwell, Jessica H; Thompson, Lester D R; Brandwein-Gensler, Margaret S; Weiss, Bernhard G; Canis, Martin; Purgina, Bibianna; Prabhu, Arpan V; Lai, Chi; Shuai, Yongli; Carroll, William R; Morlandt, Anthony; Duvvuri, Umamaheswar; Kim, Seungwon; Johnson, Jonas T; Ferris, Robert L; Seethala, Raja; Chiosea, Simion I

2015-12-01

Positive margins are associated with poor prognosis among patients with oral tongue squamous cell carcinoma (SCC). However, wide variation exists in the margin sampling technique. To determine the effect of the margin sampling technique on local recurrence (LR) in patients with stage I or II oral tongue SCC. A retrospective study was conducted from January 1, 1986, to December 31, 2012, in 5 tertiary care centers following tumor resection and elective neck dissection in 280 patients with pathologic (p)T1-2 pN0 oral tongue SCC. Analysis was conducted from June 1, 2013, to January 20, 2015. In group 1 (n = 119), tumor bed margins were not sampled. In group 2 (n = 61), margins were examined from the glossectomy specimen, found to be positive or suboptimal, and revised with additional tumor bed margins. In group 3 (n = 100), margins were primarily sampled from the tumor bed without preceding examination of the glossectomy specimen. The margin status (both as a binary [positive vs negative] and continuous [distance to the margin in millimeters] variable) and other clinicopathologic parameters were compared across the 3 groups and correlated with LR. Local recurrence. Age, sex, pT stage, lymphovascular or perineural invasion, and adjuvant radiation treatment were similar across the 3 groups. The probability of LR-free survival at 3 years was 0.9 and 0.8 in groups 1 and 3, respectively (P = .03). The frequency of positive glossectomy margins was lowest in group 1 (9 of 117 [7.7%]) compared with groups 2 and 3 (28 of 61 [45.9%] and 23 of 95 [24.2%], respectively) (P < .001). Even after excluding cases with positive margins, the median distance to the closest margin was significantly narrower in group 3 (2 mm) compared with group 1 (3 mm) (P = .008). The status (positive vs negative) of margins obtained from the glossectomy specimen correlated with LR (P = .007), while the status of tumor bed margins did not. The status of the tumor bed margin was 24% sensitive (95% CI, 16%-34%) and 92% specific (95% CI, 85%-97%) for detecting a positive glossectomy margin. The margin sampling technique affects local control in patients with oral tongue SCC. Reliance on margin sampling from the tumor bed is associated with worse local control, most likely owing to narrower margin clearance and greater incidence of positive margins. A resection specimen-based margin assessment is recommended.

Early Oral Tongue Squamous Cell Carcinoma Sampling of Margins From Tumor Bed and Worse Local Control

PubMed Central

Maxwell, Jessica H.; Thompson, Lester D. R.; Brandwein-Gensler, Margaret S.; Weiss, Bernhard G.; Canis, Martin; Purgina, Bibianna; Prabhu, Arpan V.; Lai, Chi; Shuai, Yongli; Carroll, William R.; Morlandt, Anthony; Duvvuri, Umamaheswar; Kim, Seungwon; Johnson, Jonas T.; Ferris, Robert L.; Seethala, Raja; Chiosea, Simion I.

2017-01-01

IMPORTANCE Positive margins are associated with poor prognosis among patients with oral tongue squamous cell carcinoma (SCC). However, wide variation exists in the margin sampling technique. OBJECTIVE To determine the effect of the margin sampling technique on local recurrence (LR) in patients with stage I or II oral tongue SCC. DESIGN, SETTING, AND PARTICIPANTS A retrospective study was conducted from January 1, 1986, to December 31, 2012, in 5 tertiary care centers following tumor resection and elective neck dissection in 280 patients with pathologic (p)T1-2 pN0 oral tongue SCC. Analysis was conducted from June 1, 2013, to January 20, 2015. INTERVENTIONS In group 1 (n = 119), tumor bed margins were not sampled. In group 2 (n = 61), margins were examined from the glossectomy specimen, found to be positive or suboptimal, and revised with additional tumor bed margins. In group 3 (n = 100), margins were primarily sampled from the tumor bed without preceding examination of the glossectomy specimen. The margin status (both as a binary [positive vs negative] and continuous [distance to the margin in millimeters] variable) and other clinicopathologic parameters were compared across the 3 groups and correlated with LR. MAIN OUTCOMES AND MEASURES Local recurrence. RESULTS Age, sex, pT stage, lymphovascular or perineural invasion, and adjuvant radiation treatment were similar across the 3 groups. The probability of LR-free survival at 3 years was 0.9 and 0.8 in groups 1 and 3, respectively (P = .03). The frequency of positive glossectomy margins was lowest in group 1 (9 of 117 [7.7%]) compared with groups 2 and 3 (28 of 61 [45.9%] and 23 of 95 [24.2%], respectively) (P < .001). Even after excluding cases with positive margins, the median distance to the closest margin was significantly narrower in group 3 (2 mm) compared with group 1 (3 mm) (P = .008). The status (positive vs negative) of margins obtained from the glossectomy specimen correlated with LR (P = .007), while the status of tumor bed margins did not. The status of the tumor bed margin was 24% sensitive (95% CI, 16%-34%) and 92% specific (95% CI, 85%-97%) for detecting a positive glossectomy margin. CONCLUSIONS AND RELEVANCE The margin sampling technique affects local control in patients with oral tongue SCC. Reliance on margin sampling from the tumor bed is associated with worse local control, most likely owing to narrower margin clearance and greater incidence of positive margins. A resection specimen–based margin assessment is recommended. PMID:26225798

Conveying Looming with a Localized Tactile Cue

DTIC Science & Technology

2015-04-01

leaning and reflexive head righting required at different speeds of linear or angular motion, the angle of contact of the foot to the substrate (e.g...approach information (e.g., relative distance updates) prior to actual contact , as has been reported for visual and auditory displays. A few studies have...Jacobs, 2013). Cancar et al. asked 12 subjects to estimate time-to- contact of a radially-expanding tactile or visual flow field representing a

Rapid motor learning in the translational vestibulo-ocular reflex

NASA Technical Reports Server (NTRS)

Zhou, Wu; Weldon, Patrick; Tang, Bingfeng; King, W. M.; Shelhamer, M. J. (Principal Investigator)

2003-01-01

Motor learning was induced in the translational vestibulo-ocular reflex (TVOR) when monkeys were repeatedly subjected to a brief (0.5 sec) head translation while they tried to maintain binocular fixation on a visual target for juice rewards. If the target was world-fixed, the initial eye speed of the TVOR gradually increased; if the target was head-fixed, the initial eye speed of the TVOR gradually decreased. The rate of learning acquisition was very rapid, with a time constant of approximately 100 trials, which was equivalent to <1 min of accumulated stimulation. These learned changes were consolidated over >or=1 d without any reinforcement, indicating induction of long-term synaptic plasticity. Although the learning generalized to targets with different viewing distances and to head translations with different accelerations, it was highly specific for the particular combination of head motion and evoked eye movement associated with the training. For example, it was specific to the modality of the stimulus (translation vs rotation) and the direction of the evoked eye movement in the training. Furthermore, when one eye was aligned with the heading direction so that it remained motionless during training, learning was not expressed in this eye, but only in the other nonaligned eye. These specificities show that the learning sites are neither in the sensory nor the motor limb of the reflex but in the sensory-motor transformation stage of the reflex. The dependence of the learning on both head motion and evoked eye movement suggests that Hebbian learning may be one of the underlying cellular mechanisms.

Distance and Size Perception in Astronauts during Long-Duration Spaceflight

PubMed Central

Clément, Gilles; Skinner, Anna; Lathan, Corinna

2013-01-01

Exposure to microgravity during spaceflight is known to elicit orientation illusions, errors in sensory localization, postural imbalance, changes in vestibulo-spinal and vestibulo-ocular reflexes, and space motion sickness. The objective of this experiment was to investigate whether an alteration in cognitive visual-spatial processing, such as the perception of distance and size of objects, is also taking place during prolonged exposure to microgravity. Our results show that astronauts on board the International Space Station exhibit biases in the perception of their environment. Objects’ heights and depths were perceived as taller and shallower, respectively, and distances were generally underestimated in orbit compared to Earth. These changes may occur because the perspective cues for depth are less salient in microgravity or the eye-height scaling of size is different when an observer is not standing on the ground. This finding has operational implications for human space exploration missions. PMID:25369884

Redefining Practice: Challenging Academic and Institutional Traditions with Clinical Distance Learning

ERIC Educational Resources Information Center

Delgaty, Laura E.

2017-01-01

With the uptake of distance learning (DL), which has actually been marginal for most academics, teaching contexts, traditional power structures and relationships have been transformed, leaving lecturers potentially disenfranchised. Institutional and cultural change is vital, particularly changes concerning academic roles. The advent of DL has…

Localization of the cutaneus trunci muscle reflex in horses.

PubMed

Essig, Cynthia M; Merritt, Jonathan S; Stubbs, Narelle C; Clayton, Hilary M

2013-11-01

To determine the magnitude and location of skin movement attributable to the cutaneus trunci muscle reflex in response to localized stimulation of the skin of the dorsolateral aspect of the thoracic wall in horses. 8 horses. A grid of 56 reflective markers was applied to the lateral aspect of the body wall of each horse; markers were placed at 10-cm intervals in 7 rows and 8 columns. A motion analysis system with 10 infrared cameras was used to track movements of the markers in response to tactile stimulation of the dorsolateral aspect of the thoracic wall at the levels of T6, T11, and T16. Marker movement data determined after skin stimulation were used to create a skin deformation gradient tensor field, which was analyzed with custom software. The sites of maximal skin deformation were located close to the stimulation sites; the centers of the twitch responses were located a mean distance of 7.7 to 12.8 cm ventral and between 6.6 cm cranial and 3.1 cm caudal to the stimulation sites. Findings of this study may have implications for assessment of nerve conduction velocities of the cutaneus trunci muscle reflex and may enhance understanding of the responses of horses to placement of tack or other equipment on skin over the cutaneus trunci muscles.

Simultaneous Versus Sequential Ptosis and Strabismus Surgery in Children.

PubMed

Revere, Karen E; Binenbaum, Gil; Li, Jonathan; Mills, Monte D; Katowitz, William R; Katowitz, James A

The authors sought to compare the clinical outcomes of simultaneous versus sequential ptosis and strabismus surgery in children. Retrospective, single-center cohort study of children requiring both ptosis and strabismus surgery on the same eye. Simultaneous surgeries were performed during a single anesthetic event; sequential surgeries were performed at least 7 weeks apart. Outcomes were ptosis surgery success (margin reflex distance 1 ≥ 2 mm, good eyelid contour, and good eyelid crease); strabismus surgery success (ocular alignment within 10 prism diopters of orthophoria and/or improved head position); surgical complications; and reoperations. Fifty-six children were studied, 38 had simultaneous surgery and 18 sequential. Strabismus surgery was performed first in 38/38 simultaneous and 6/18 sequential cases. Mean age at first surgery was 64 months, with mean follow up 27 months. A total of 75% of children had congenital ptosis; 64% had comitant strabismus. A majority of ptosis surgeries were frontalis sling (59%) or Fasanella-Servat (30%) procedures. There were no significant differences between simultaneous and sequential groups with regards to surgical success rates, complications, or reoperations (all p > 0.28). In the first comparative study of simultaneous versus sequential ptosis and strabismus surgery, no advantage for sequential surgery was seen. Despite a theoretical risk of postoperative eyelid malposition or complications when surgeries were performed in a combined manner, the rate of such outcomes was not increased with simultaneous surgeries. Performing ptosis and strabismus surgery together appears to be clinically effective and safe, and reduces anesthesia exposure during childhood.

Evaluation of concordance between CAD/CAM and clinical positions of abutment shoulder against mucosal margin: an observational study.

PubMed

Pietruski, Jan K; Skurska, Anna; Bernaczyk, Anna; Milewski, Robert; Pietruska, Maria Julia; Gehrke, Peter; Pietruska, Małgorzata D

2018-05-02

While working on CAD/CAM-customized abutments, the use of standard impression copings with a circular diameter produces inconsistency within the emergence profile. It may begin with a collapse of the supra-implant mucosa during impression taking, then lead to a computer-generated mismatch of the position and outline of the abutment shoulder, and consequently result in a compromised outcome of anticipated treatment. The aim of the study was to compare the virtual and clinical positions of the abutment shoulder in relation to the mucosal margin after the abutment delivery. Conventional open-tray impression takings followed uncovering surgery. Master casts were scanned with a desktop scanner. Clinical examinations took place after abutment's insertion and temporization (T1) and prior to cementation of the definitive crown (T2). The distances between the abutment shoulder and marginal soft tissue were measured intraorally in four aspects and juxtaposed with those on the virtual model. The study evaluated 257 dental implants and CAD/CAM-customized abutments. As T1 and T2 showed, there was a positive correlation between the virtually designed abutment shoulder position and matching clinical location relative to the mucosal margin. In 42.1% of cases, the distance between the mucosal margin and the abutment shoulder did not change. It increased in 36.3% of cases while a decrease occurred in 21.6% of them. Computer-set position of the abutment shoulder in relation to the mucosal margin can be predictably implemented in clinical practice.

INTEGRATION OF RELIABILITY WITH MECHANISTIC THERMALHYDRAULICS: REPORT ON APPROACH AND TEST PROBLEM RESULTS

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

J. S. Schroeder; R. W. Youngblood

The Risk-Informed Safety Margin Characterization (RISMC) pathway of the Light Water Reactor Sustainability Program is developing simulation-based methods and tools for analyzing safety margin from a modern perspective. [1] There are multiple definitions of 'margin.' One class of definitions defines margin in terms of the distance between a point estimate of a given performance parameter (such as peak clad temperature), and a point-value acceptance criterion defined for that parameter (such as 2200 F). The present perspective on margin is that it relates to the probability of failure, and not just the distance between a nominal operating point and a criterion.more » In this work, margin is characterized through a probabilistic analysis of the 'loads' imposed on systems, structures, and components, and their 'capacity' to resist those loads without failing. Given the probabilistic load and capacity spectra, one can assess the probability that load exceeds capacity, leading to component failure. Within the project, we refer to a plot of these probabilistic spectra as 'the logo.' Refer to Figure 1 for a notional illustration. The implications of referring to 'the logo' are (1) RISMC is focused on being able to analyze loads and spectra probabilistically, and (2) calling it 'the logo' tacitly acknowledges that it is a highly simplified picture: meaningful analysis of a given component failure mode may require development of probabilistic spectra for multiple physical parameters, and in many practical cases, 'load' and 'capacity' will not vary independently.« less

Acculturative Stress and Depressive Symptomatology Among Mexican and Mexican American Students in the U.S.: Examining Associations with Cultural Incongruity and Intragroup Marginalization

PubMed Central

Cano, Miguel Ángel; Castillo, Linda G.; Castro, Yessenia; de Dios, Marcel A.

2013-01-01

This study examined associations of intragroup marginalization and cultural incongruity with acculturative stress and depressive symptoms among 155 undergraduate U.S. college students of Mexican heritage. Findings indicate that perceived interpersonal distancing by the family (intragroup marginalization) and perceived lack of cultural fit between the respondent and academic institution (cultural incongruity) had statistically significant direct and indirect effects on depressive symptoms via acculturative stress. Results also show that 39.7 % of the variance corresponding with depressive symptoms was accounted for by intragroup marginalization, cultural incongruity, acculturative stress, and other exogenous variables. PMID:24791033

Functions, Use and Effects of Embedded Support Devices in Printed Distance Learning Materials.

ERIC Educational Resources Information Center

Martens, Rob; And Others

1996-01-01

To support distance learning, printed materials for the course are enriched with embedded support devices (ESD) such as schemes, illustrations, examples, questions, or margin texts. Results of 3 studies involving 900 Dutch university students indicated that students used and appreciated ESD, and that they led to better study results. (SLD)

Lithosphere erosion and continental breakup: Interaction of extension, plume upwelling and melting

NASA Astrophysics Data System (ADS)

Lavecchia, Alessio; Thieulot, Cedric; Beekman, Fred; Cloetingh, Sierd; Clark, Stuart

2017-06-01

We present the results of thermo-mechanical modelling of extension and breakup of a heterogeneous continental lithosphere, subjected to plume impingement in presence of intraplate stress field. We incorporate partial melting of the extending lithosphere, underlying upper mantle and plume, caused by pressure-temperature variations during the thermo-mechanical evolution of the conjugate passive margin system. Effects of melting included in the model account for thermal effects, causing viscosity reduction due to host rock heating, and mechanical effects, due to cohesion loss. Our study provides better understanding on how presence of melts can influence the evolution of rifting. Here we focus particularly on the role of melting for the temporal and spatial evolution of passive margin geometry and rift migration. Depending on the lithospheric structure, melt presence may have a significant impact on the characteristics of areas affected by lithospheric extension. Pre-existing lithosphere heterogeneities determine the location of initial breakup, but in presence of plumes the subsequent evolution is more difficult to predict. For small distances between plume and area of initial rifting, the development of symmetric passive margins is favored, whereas increasing the distance promotes asymmetry. For a plume-rifting distance large enough to prevent interaction, the effect of plumes on the overlying lithosphere is negligible and the rift persists at the location of the initial lithospheric weakness. When the melt effect is included, the development of asymmetric passive continental margins is fostered. In this case, melt-induced lithospheric weakening may be strong enough to cause rift jumps toward the plume location.

How the fluctuations of water levels affect populations of invasive bivalve Corbicula fluminea (Müller, 1774) in a Neotropical reservoir?

PubMed

Paschoal, L R P; Andrade, D P; Darrigran, G

2015-01-01

Corbicula fluminea is an invasive bivalve responsible for several environmental and financial problems around the globe. Despite the invasive potential of this species, it suffers certain restrictions in lentic environments due to natural phenomena that significantly affect its population structure (e.g. water column fluctuation and sunlight exposure). The present study addresses how temporal decline of the water level in a Neotropical reservoir and exposure to sunlight affect the population structure of C. fluminea. Samplings were carried out twice in the reservoir of Furnas Hydroelectric Power Station (HPS) (Minas Gerais, Brazil), in 2011 and 2012. Population density, spatial distribution and mean shell length of C. fluminea were estimated for each year after sampling in 51 quadrats (0.0625m2) placed on three transects at different distances along the reservoir margins (0, 10 and 20 m from a fixed-point). We observed a predominance of C. fluminea in both years, with a simultaneous gradual decrease in density and richness of native species in the sampling area. Significant differences in density of C. fluminea were registered at different distances from the margin, and are related to the temporal variability of physical conditions of the sediment and water in these environments. We also registered a trend toward an increase in the density and aggregation of C. fluminea as we moved away from the margin, due to the greater stability of these areas (>10 m). The mean shell length of C. fluminea showed significant difference between the distinct distances from the margin and during the years, as well as the interaction of these factors (Distances vs.Years). These results were associated with the reproductive and invasive capacity of this species. This study reveals that these temporal events (especially water column fluctuation) may cause alterations in density, spatial distribution and mean shell length of C. fluminea and the composition of the native malacofauna in Neotropical lentic environments.

Epilepsy caused by an abnormal alternative splicing with dosage effect of the SV2A gene in a chicken model.

PubMed

Douaud, Marine; Feve, Katia; Pituello, Fabienne; Gourichon, David; Boitard, Simon; Leguern, Eric; Coquerelle, Gérard; Vieaud, Agathe; Batini, Cesira; Naquet, Robert; Vignal, Alain; Tixier-Boichard, Michèle; Pitel, Frédérique

2011-01-01

Photosensitive reflex epilepsy is caused by the combination of an individual's enhanced sensitivity with relevant light stimuli, such as stroboscopic lights or video games. This is the most common reflex epilepsy in humans; it is characterized by the photoparoxysmal response, which is an abnormal electroencephalographic reaction, and seizures triggered by intermittent light stimulation. Here, by using genetic mapping, sequencing and functional analyses, we report that a mutation in the acceptor site of the second intron of SV2A (the gene encoding synaptic vesicle glycoprotein 2A) is causing photosensitive reflex epilepsy in a unique vertebrate model, the Fepi chicken strain, a spontaneous model where the neurological disorder is inherited as an autosomal recessive mutation. This mutation causes an aberrant splicing event and significantly reduces the level of SV2A mRNA in homozygous carriers. Levetiracetam, a second generation antiepileptic drug, is known to bind SV2A, and SV2A knock-out mice develop seizures soon after birth and usually die within three weeks. The Fepi chicken survives to adulthood and responds to levetiracetam, suggesting that the low-level expression of SV2A in these animals is sufficient to allow survival, but does not protect against seizures. Thus, the Fepi chicken model shows that the role of the SV2A pathway in the brain is conserved between birds and mammals, in spite of a large phylogenetic distance. The Fepi model appears particularly useful for further studies of physiopathology of reflex epilepsy, in comparison with induced models of epilepsy in rodents. Consequently, SV2A is a very attractive candidate gene for analysis in the context of both mono- and polygenic generalized epilepsies in humans.

Determination of the Nonlethal Margin Inside the Visible 'Ice-Ball' During Percutaneous Cryoablation of Renal Tissue

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

Georgiades, Christos, E-mail: g_christos@hotmail.com; Rodriguez, Ronald, E-mail: rrodrig@jhmi.edu; Azene, Ezana, E-mail: eazene1@jhmi.edu

2013-06-15

Objective. The study was designed to determine the distance between the visible 'ice-ball' and the lethal temperature isotherm for normal renal tissue during cryoablation. Methods. The Animal Care Committee approved the study. Nine adult swine were used: three to determine the optimum tissue stain and six to test the hypotheses. They were anesthetized and the left renal artery was catheterized under fluoroscopy. Under MR guidance, the kidney was ablated and (at end of a complete ablation) the nonfrozen renal tissue (surrounding the 'ice-ball') was stained via renal artery catheter. Kidneys were explanted and sent for slide preparation and examination. Frommore » each slide, we measured the maximum, minimum, and an in-between distance from the stained to the lethal tissue boundaries (margin). We examined each slide for evidence of 'heat pump' effect. Results. A total of 126 measurements of the margin (visible 'ice-ball'-lethal margin) were made. These measurements were obtained from 29 slides prepared from the 6 test animals. Mean width was 0.75 {+-} 0.44 mm (maximum 1.15 {+-} 0.51 mm). It was found to increase adjacent to large blood vessels. No 'heat pump' effect was noted within the lethal zone. Data are limited to normal swine renal tissue. Conclusions. Considering the effects of the 'heat pump' phenomenon for normal renal tissue, the margin was measured to be 1.15 {+-} 0.51 mm. To approximate the efficacy of the 'gold standard' (partial nephrectomy, {approx}98 %), a minimum margin of 3 mm is recommended (3 Multiplication-Sign SD). Given these assumptions and extrapolating for renal cancer, which reportedly is more cryoresistant with a lethal temperature of -40 Degree-Sign C, the recommended margin is 6 mm.« less

Contradictions in a Distance Course for a Marginalized Population at a Middle Eastern University

ERIC Educational Resources Information Center

Madyarov, Irshat; Taef, Aida

2012-01-01

This study explores six cases of non-native English speaking students engaged in a distance English-medium course on critical thinking at a university in Iran. Framed within activity theory, the study investigated students' course-related activity systems with a particular focus on contradictions that underlie any human activity. The construct of…

Infant reflexes

MedlinePlus

... infants; Tonic neck reflex; Galant reflex; Truncal incurvation; Rooting reflex; Parachute reflex; Grasp reflex ... up if both hands are grasping your fingers. ROOTING REFLEX This reflex occurs when the baby's cheek ...

Distance Mathematics Education as a Means for Tackling Impulse Control Disorder: The Case of a Young Convict

ERIC Educational Resources Information Center

Ahl, Linda; Aguilar, Mario Sánchez; Jankvist, Uffe Thomas

2017-01-01

While distance education (DE) is often considered as a means to provide mathematical education to students in remote locations or to promote the professional development of mathematics teachers, this article reports a case showing that DE may also be useful in providing mathematical instruction to individuals who are marginalized or disadvantaged…

Infraorbital foramen: horizontal location in relation to ala nasi.

PubMed

Takahashi, Yasuhiro; Kakizaki, Hirohiko; Nakano, Takashi

2011-01-01

To examine the horizontal location of the infraorbital foramen in relation to the ala nasi. Fifty-six orbits of 28 Japanese cadavers (18 male and 10 female cadavers; average death age, 79.7 years), fixed in 10% buffered formalin, were used. The horizontal distance from the vertical line through the lateral margin of the ala nasi to the medial margin of the infraorbital foramen (the horizontal distance) and the transverse diameter of the infraorbital foramen (the transverse diameter) were examined. Values were compared between genders and sides using Student's t test. The mean horizontal distance was 4.9 mm, with no significant difference between genders (male, 5.2 mm; female, 4.4 mm; p = 0.150) or sides (right, 4.9 mm; left, 4.9 mm; p = 0.944). The mean transverse diameter was 5.5 mm. Although there was no significant difference in this diameter between sides (right, 5.3 mm; left, 5.6 mm; p = 0.358), there was a significant difference between genders (male, 5.7 mm; female, 5.1 mm; p = 0.033). The horizontal distance had no gender difference. This value is available irrespective of gender in surgery.

Edge Effects along a Seagrass Margin Result in an Increased Grazing Risk on Posidonia australis Transplants.

PubMed

Statton, John; Gustin-Craig, Samuel; Dixon, Kingsley W; Kendrick, Gary A

2015-01-01

A key issue in habitat restoration are the changes in ecological processes that occur when fragments of habitat are lost, resulting in the persistence of habitat-degraded margins. Margins often create or enhance opportunities for negative plant-herbivore interactions, preventing natural or assisted re-establishment of native vegetation into the degraded area. However, at some distance from the habitat margin these negative interactions may relax. Here, we posit that the intensity of species interactions in a fragmented Posidonia australis seagrass meadow may be spatially dependent on proximity to the seagrass habitat edge, whereby the risk of grazing is high and the probability of survival of seagrass transplants is low. To test this, transplants were planted 2 m within the meadow, on the meadow edge at 0m, and at 2m, 10m, 30m, 50m and 100m distance from the edge of the seagrass meadow into the unvegetated sand sheet. There was an enhanced grazing risk 0-10m from the edge, but decreased sharply with increasing distances (>30m). Yet, the risk of grazing was minimal inside the seagrass meadow, indicating that grazers may use the seagrass meadow for refuge but are not actively grazing within it. The relationship between short-term herbivory risk and long-term survival was not straightforward, suggesting that other environmental filters are also affecting survival of P. australis transplants within the study area. We found that daily probability of herbivory was predictable and operating over a small spatial scale at the edge of a large, intact seagrass meadow. These findings highlight the risk from herbivory can be high, and a potential contributing factor to seagrass establishment in restoration programs.

Edge Effects along a Seagrass Margin Result in an Increased Grazing Risk on Posidonia australis Transplants

PubMed Central

Statton, John; Gustin-Craig, Samuel; Dixon, Kingsley W.; Kendrick, Gary A.

2015-01-01

A key issue in habitat restoration are the changes in ecological processes that occur when fragments of habitat are lost, resulting in the persistence of habitat-degraded margins. Margins often create or enhance opportunities for negative plant-herbivore interactions, preventing natural or assisted re-establishment of native vegetation into the degraded area. However, at some distance from the habitat margin these negative interactions may relax. Here, we posit that the intensity of species interactions in a fragmented Posidonia australis seagrass meadow may be spatially dependent on proximity to the seagrass habitat edge, whereby the risk of grazing is high and the probability of survival of seagrass transplants is low. To test this, transplants were planted 2 m within the meadow, on the meadow edge at 0m, and at 2m, 10m, 30m, 50m and 100m distance from the edge of the seagrass meadow into the unvegetated sand sheet. There was an enhanced grazing risk 0-10m from the edge, but decreased sharply with increasing distances (>30m). Yet, the risk of grazing was minimal inside the seagrass meadow, indicating that grazers may use the seagrass meadow for refuge but are not actively grazing within it. The relationship between short-term herbivory risk and long-term survival was not straightforward, suggesting that other environmental filters are also affecting survival of P. australis transplants within the study area. We found that daily probability of herbivory was predictable and operating over a small spatial scale at the edge of a large, intact seagrass meadow. These findings highlight the risk from herbivory can be high, and a potential contributing factor to seagrass establishment in restoration programs. PMID:26465926

White-Tailed Deer Response to Vehicle Approach: Evidence of Unclear and Present Danger

PubMed Central

Blackwell, Bradley F.; Seamans, Thomas W.; DeVault, Travis L.

2014-01-01

The fundamental causes of animal-vehicle collisions are unclear, particularly at the level of animal detection of approaching vehicles and decision-making. Deer-vehicle collisions (DVCs) are especially costly in terms of animal mortality, property damage, and safety. Over one year, we exposed free-ranging white-tailed deer (Odocoileus virginianus) to vehicle approach under low ambient light conditions, from varying start distances, and vehicle speeds from 20 km/h to approximately 90 km/h. We modeled flight response by deer to an approaching vehicle and tested four hypotheses: 1) flight-initiation distance (FID) would correlate positively with start distance (indicating a spatial margin of safety); 2) deer would react to vehicle speed using a temporal margin of safety; 3) individuals reacting at greater FIDs would be more likely to cross the path of the vehicle; and 4) crossings would correlate positively with start distance, approach speed, and distance to concealing/refuge cover. We examined deer responses by quantiles. Median FID was 40% of start distance, irrespective of start distance or approach speed. Converting FID to time-to-collision (TTC), median TTC was 4.6 s, but uncorrelated with start distance or approach speed. The likelihood of deer crossing in front of the vehicle was not associated with greater FIDs or other explanatory variables. Because deer flight response to vehicle approach was highly variable, DVCs should be more likely with increasing vehicle speeds because of lower TTCs for a given distance. For road sections characterized by frequent DVCs, we recommend estimating TTC relative to vehicle speed and candidate line-of-sight distances adjusted downward by (1-P), where P represents our findings for the proportion of start distance by which >75% of deer had initiated flight. Where road design or conservation goals limit effectiveness of line-of-sight maintenance, we suggest incorporation of roadway obstacles that force drivers to slow vehicles, in addition to posting advisory speed limits. PMID:25333922

A comparative study of accuracy of linear measurements using cone beam and multi-slice computed tomographies for evaluation of mandibular canal location in dry mandibles.

PubMed

Naser, Asieh Zamani; Mehr, Bahar Behdad

2013-01-01

Cross- sectional tomograms have been used for optimal pre-operative planning of dental implant placement. The aim of the present study was to assess the accuracy of Cone Beam Computed Tomography (CBCT) measurements of specific distances around the mandibular canal by comparing them to those obtained from Multi-Slice Computed Tomography (MSCT) images. Ten hemi-mandible specimens were examined using CBCT and MSCT. Before imaging, wires were placed at 7 locations between the anterior margin of the third molar and the anterior margin of the second premolar as reference points. Following distances were measured by two observers on each cross-sectional CBCT and MSCT image: Mandibular Width (W), Length (L), Upper Distance (UD), Lower Distance (LD), Buccal Distance (BD), and Lingual Distance (LID). The obtained data were evaluated using SPSS software, applying paired t-test and intra-class correlation coefficient (ICC). There was a significant difference between the values obtained by MSCT and CBCT measurement for all areas such as H, W, UD, LD, BD, and LID, (P < 0.001), with a difference less than 1 mm. The ICC for all distances by both techniques, measured by a single observer with a one week interval and between 2 observers was 99% and 98%, respectively. Comparing the obtained data of both techniques indicates that the difference between two techniques is 2.17% relative to MSCT. The results of this study showed that there is significant difference between measurements obtained by CBCT and MSCT. However, the difference is not clinically significant.

Presurgical functional magnetic resonance imaging in patients with brain tumors.

PubMed

Ravn, Søren; Holmberg, Mats; Sørensen, Preben; Frokjaer, Jens B; Carl, Jesper

2016-01-01

Clinical functional magnetic resonance imaging (fMRI) is still an upcoming diagnostic tool because it is time-consuming to perform the post-scan calculations and interpretations. A standardized and easily used method for the clinical assessment of fMRI scans could decrease the workload and make fMRI more attractive for clinical use. To evaluate a standardized clinical approach for distance measurement between benign brain tumors and eloquent cortex in terms of the ability to predict pre- and postoperative neurological deficits after intraoperative neuronavigation-assisted surgery. A retrospective study of 34 patients. The fMRI data were reanalyzed using a standardized distance measurement procedure combining data from both fMRI and three-dimensional T1 MRI scans. The pre- and postoperative neurological status of each patient was obtained from hospital records. Data analysis was performed using logistic regression analysis to determine whether the distance measured between the tumor margin and fMRI activity could serve as a predictor for neurological deficits. An odds ratio of 0.89 mm(-1) (P = 0.03) was found between the risk of preoperative neurological motor deficits and the tumor-fMRI distance. An odds ratio of 0.82 mm(-1) (P = 0.04) was found between the risk of additional postoperative neurological motor deficits and the tumor-fMRI distance. The tumor was radically removed in 10 cases; five patients experienced additional postoperative motor deficits (tumor-fMRI distance <18 mm) and five did not (tumor-fMRI distance >18 mm) (P = 0.008). This study indicates that the distance measured between the tumor margin and fMRI activation could serve as a valuable predictor of neurological motor deficits. © The Foundation Acta Radiologica 2014.

Effect of viewing distance and location of the axis of head rotation on the monkey's vestibuloocular reflex. I. Eye movement responses.

PubMed

Snyder, L H; King, W M

1992-04-01

1. The vestibuloocular reflex (VOR) stabilizes images on the retina against movements of the head in space. Viewing distance, target eccentricity, and location of the axis of rotation may influence VOR responses because rotation of the head about most axes in space rotates and translates the eyes relative to visual targets. To study the VOR response to combined rotation and translation, monkeys were placed on a rate table and rotated briefly in the dark about a vertical axis that was located in front of or behind the eyes. The monkeys fixated a near or far visual target that was extinguished before the rotation. Eye movements were recorded from both eyes by the use of the search coil technique. 2. Peak eye velocity evoked by the VOR was linearly related to vergence angle for any axis of rotation. The percent change in the VOR with near target viewing relative to far target viewing at a vergence angle of 20 degrees was linearly related to the location of the axis of rotation. Axes located behind the eyes produced positive changes in VOR amplitude, and axes located in front of the eyes produced negative changes in VOR amplitude. An axis of rotation located in the coronal plane containing the centers of rotation of the eyes produced no modification of VOR amplitude. For any axis, the VOR compensated for approximately 90% of the translation of the eye relative to near targets. 3. The initial VOR response was not correct in magnitude but was refined by a series of three temporally delayed corrections of increasing complexity. The earliest VOR-evoked eye movement (10-20 ms after rotation onset) was independent of viewing distance and rotational axis location. In the next 100 ms, eye speed appeared to be sequentially modified three times: within 20 ms by viewing distance; within 30 ms by otolith translation; and within 100 ms by eye translation relative to the visual target. 4. These data suggest a formal model of the VOR consisting of four channels. Channel 1 conveys an unmodified head rotation signal with a pure delay of 10 ms. Channel 2 conveys an angular head velocity signal, modified by viewing distance with a pure delay of 20 ms, but invariant with respect to the location of the axis of rotation. Channel 3 conveys a linear head velocity signal, dependent on the location of the axis of rotation, that is modified by viewing distance with a pure delay of 30 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Tumor margin detection using optical biopsy techniques

NASA Astrophysics Data System (ADS)

Zhou, Yan; Liu, Cheng-hui; Li, Jiyou; Li, Zhongwu; Zhou, Lixin; Chen, Ke; Pu, Yang; He, Yong; Zhu, Ke; Li, Qingbo; Alfano, Robert R.

2014-03-01

The aim of this study is to use the Resonance Raman (RR) and fluorescence spectroscopic technique for tumor margin detection with high accuracy based on native molecular fingerprints of breast and gastrointestinal (GI) tissues. This tumor margins detection method utilizes advantages of RR spectroscopic technique in situ and in real-time to diagnose tumor changes providing powerful tools for clinical guiding intraoperative margin assessments and postoperative treatments. The tumor margin detection procedures by RR spectroscopy were taken by scanning lesion from center or around tumor region in ex-vivo to find the changes in cancerous tissues with the rim of normal tissues using the native molecular fingerprints. The specimens used to analyze tumor margins include breast and GI carcinoma and normal tissues. The sharp margin of the tumor was found by the changes of RR spectral peaks within 2 mm distance. The result was verified using fluorescence spectra with 300 nm, 320 nm and 340 nm excitation, in a typical specimen of gastric cancerous tissue within a positive margin in comparison with normal gastric tissues. This study demonstrates the potential of RR and fluorescence spectroscopy as new approaches with labeling free to determine the intraoperative margin assessment.

Simulation of a G-tolerance curve using the pulsatile cardiovascular model

NASA Technical Reports Server (NTRS)

Solomon, M.; Srinivasan, R.

1985-01-01

A computer simulation study, performed to assess the ability of the cardiovascular model to reproduce the G tolerance curve (G level versus tolerance time) is reported. A composite strength duration curve derived from experimental data obtained in human centrifugation studies was used for comparison. The effects of abolishing automomic control and of blood volume loss on G tolerance were also simulated. The results provide additional validation of the model. The need for the presence of autonomic reflexes even at low levels of G is pointed out. The low margin of safety with a loss of blood volume indicated by the simulation results underscores the necessity for protective measures during Shuttle reentry.

Emotion work, ethnography, and survival strategies on the streets of Yogyakarta.

PubMed

Stodulka, Thomas

2015-01-01

Anthropological research with street-related children, adolescents, and young adults raises epistemological, methodical, and ethical predicaments. In this article, I illustrate the advantages of an anthropology that acknowledges the ethnographer's emotions as valuable data when conducting research with marginalized communities. By drawing on my own experiences when conducting long-term fieldwork, I argue that systematic self-reflexivity and an emotionally aware epistemology enhance both the anthropologist's emotional literacy and his or her understanding of informants and interlocutors. The integration of the ethnographer's emotions in the analysis and interpretation of ethnographic data can assist in formulating anthropological theory, challenging the limits of traditional empiricism, and raising emotions to a category of epistemic value.

Pediatric ptosis as a sign of treatable autonomic dysfunction.

PubMed

Phillips, Lara; Robertson, David; Melson, Mark R; Garland, Emily M; Joos, Karen M

2013-08-01

To report the ophthalmic findings in young patients with dopamine β-hydroxylase deficiency and to assess them in the context of other reports in an attempt to discern if ophthalmic criteria may assist in early detection of this debilitating, yet treatable, disorder. Prospective, observational case series. An ophthalmic examination, including measuring intraocular and systemic blood pressures while supine, sitting, and standing, and eyelid function and pupillary function testing, was completed on 3 young patients with recently documented dopamine β-hydroxylase deficiency at a single institution. Mean arterial blood pressures were 90.1 ± 18.5 mm Hg supine, 79.1 ± 25.7 mm Hg sitting, and 45.8 ± 11.6 mm Hg standing (P = .021). Mean intraocular pressures in these patients were 15.8 ± 1.0 mm Hg supine, 15.0 ± 3.6 mm Hg sitting, and 7.7 ± 2.3 mm Hg standing (P = .03). Mean palpebral fissure, levator function, and margin reflex distance were 8.2 ± 1.0 mm, 16.0 ± 0 mm, and 2.8 ± 0.6 mm, respectively. Measurable miosis was present in only 1 patient, and pupillary supersensitivity to 2.5% phenylephrine was not observed. The ophthalmologic findings of the patients in this case series documented mild ptosis and striking orthostatic reductions in intraocular pressure and mean arterial blood pressure, as might be expected with a lack of intrinsic sympathetic function. Orthostatic intraocular pressure and mean arterial blood pressure may be a helpful early screening tool for autonomic dysfunction in children undergoing a ptosis evaluation. Copyright © 2013 Elsevier Inc. All rights reserved.

Structure and rheology of the lithosphere below southeastern margin of India and Sri Lanka, and its conjugate segment of the east Antarctica: Implications on early breakup history and margin formation

NASA Astrophysics Data System (ADS)

Rao Gangumalla, Srinivasa; Radhakrishna, Munukutla

2014-05-01

The eastern continental margin of India has evolved as a consequence of rifting and breakup between India and east Antarctica during the early Cretaceous. Plate reconstruction models for the breakup of eastern Gondwanaland by many earlier workers have unambiguously placed the southeast margin of Sri Lanka and India together as a conjugate segment with the east Antarctica margin that extends from Gunnerus Ridge in the west to western Enderby basin in the east. In this study, we present results of integrated analysis of gravity, geoid, magnetic and seismic data from these two conjugate portions in order to examine the lithosphere structure and early seafloor spreading, style of breakup, continent-ocean boundary (COB) and rheological characteristics at these margins. The interpreted COB lies at a distance of 55-140 km on the side of southeast margin of Sri Lanka and India, whereas, it lies at a distance of 190-550 km on the side of east Antarctica margin. The seismic profiles and the constrained potential field models across these two segments do not show the existence of seaward dipping reflector sequences or magmatic underplating suggesting that these segments have not encountered major magmatic activity. While, significant crustal thinning/stretching is observed at the east Antarctic margin, the Cauvery offshore had experienced limited stretching with faulted Moho interface. Further, the conspicuous residual geoid low in the Cauvery offshore basin is inferred to be due to a continental crustal block. The modelled Lithosphere-Astenosphere Boundary (LAB) in these two margins is located around 110-120 km depth with slightly thicker lithosphere at the east Antarctica margin. In addition, the interpretation of magnetic anomalies provided structure of the oceanic crust generated through seafloor spreading processes with age and magnetization data constrained from the identified magnetic anomalies in the respective margins. Using the Bouguer coherence method, we computed spatial variations in effective elastic thickness (Te) at these margin segments. The estimated Te values at the Indian margin ranges between 5-8 km in the southeast of Sri Lanka to around 10-12 km in the Cauvery offshore which decrease further north to < 5 km in the Cauvery-Palar basin. Along the east Antarctic margin, the Te values ranges between 5-10 km in the Gunnerus ridge region, 35-40 km in the western Enderby basin which decrease further towards the central Enderby basin up to 20 km. In this study, the above results have been analyzed in terms of early breakup mechanism and subsequent evolution of these two conjugate segments.

Effect of viewing distance on the generation of vertical eye movements during locomotion

NASA Technical Reports Server (NTRS)

Moore, S. T.; Hirasaki, E.; Cohen, B.; Raphan, T.

1999-01-01

Vertical head and eye coordination was studied as a function of viewing distance during locomotion. Vertical head translation and pitch movements were measured using a video motion analysis system (Optotrak 3020). Vertical eye movements were recorded using a video-based pupil tracker (Iscan). Subjects (five) walked on a linear treadmill at a speed of 1.67 m/s (6 km/h) while viewing a target screen placed at distances ranging from 0.25 to 2.0 m at 0. 25-m intervals. The predominant frequency of vertical head movement was 2 Hz. In accordance with previous studies, there was a small head pitch rotation, which was compensatory for vertical head translation. The magnitude of the vertical head movements and the phase relationship between head translation and pitch were little affected by viewing distance, and tended to orient the naso-occipital axis of the head at a point approximately 1 m in front of the subject (the head fixation distance or HFD). In contrast, eye velocity was significantly affected by viewing distance. When viewing a far (2-m) target, vertical eye velocity was 180 degrees out of phase with head pitch velocity, with a gain of 0. 8. This indicated that the angular vestibulo-ocular reflex (aVOR) was generating the eye movement response. The major finding was that, at a close viewing distance (0.25 m), eye velocity was in phase with head pitch and compensatory for vertical head translation, suggesting that activation of the linear vestibulo-ocular reflex (lVOR) was contributing to the eye movement response. There was also a threefold increase in the magnitude of eye velocity when viewing near targets, which was consistent with the goal of maintaining gaze on target. The required vertical lVOR sensitivity to cancel an unmodified aVOR response and generate the observed eye velocity magnitude for near targets was almost 3 times that previously measured. Supplementary experiments were performed utilizing body-fixed active head pitch rotations at 1 and 2 Hz while viewing a head-fixed target. Results indicated that the interaction of smooth pursuit and the aVOR during visual suppression could modify both the gain and phase characteristics of the aVOR at frequencies encountered during locomotion. When walking, targets located closer than the HFD (1.0 m) would appear to move in the same direction as the head pitch, resulting in suppression of the aVOR. The results of the head-fixed target experiment suggest that phase modification of the aVOR during visual suppression could play a role in generating eye movements consistent with the goal of maintaining gaze on targets closer than the HFD, which would augment the lVOR response.

The importance of familia for Latina/o college students: examining the role of familial support in intragroup marginalization.

PubMed

Llamas, Jasmín D; Morgan Consoli, Melissa

2012-10-01

Intragroup marginalization refers to the perceived interpersonal distancing by members of the heritage culture when an individual exhibits cultural characteristics of the dominant group. This study expands understanding of the college experience of Latina/o students by examining relationships between intragroup marginalization, college adjustment, resilience, and thriving in a sample of 181 Latina/o college students, ranging from freshman to graduate students. In addition, the role of familial social support is explored to determine any possible mediating effects on the relationship between intragroup marginalization, college adjustment, resilience, and thriving. Findings revealed that intragroup marginalization predicted college adjustment, resilience, and thriving. Familial social support was found to mediate the relationship between intragroup marginalization and thriving. This research highlights the negative impact of intragroup marginalization for Latina/o students, as well as the role of familial support in thriving. The results also shed light on the Latina/o college experience as a means to improving Latina/o students' college outcomes. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

A quantitative analysis of transtensional margin width

NASA Astrophysics Data System (ADS)

Jeanniot, Ludovic; Buiter, Susanne J. H.

2018-06-01

Continental rifted margins show variations between a few hundred to almost a thousand kilometres in their conjugated widths from the relatively undisturbed continent to the oceanic crust. Analogue and numerical modelling results suggest that the conjugated width of rifted margins may have a relationship to their obliquity of divergence, with narrower margins occurring for higher obliquity. We here test this prediction by analysing the obliquity and rift width for 26 segments of transtensional conjugate rifted margins in the Atlantic and Indian Oceans. We use the plate reconstruction software GPlates (http://www.gplates.org) for different plate rotation models to estimate the direction and magnitude of rifting from the initial phases of continental rifting until breakup. Our rift width corresponds to the distance between the onshore maximum topography and the last identified continental crust. We find a weak positive correlation between the obliquity of rifting and rift width. Highly oblique margins are narrower than orthogonal margins, as expected from analogue and numerical models. We find no relationships between rift obliquities and rift duration nor the presence or absence of Large Igneous Provinces (LIPs).

Product Quality Modelling Based on Incremental Support Vector Machine

NASA Astrophysics Data System (ADS)

Wang, J.; Zhang, W.; Qin, B.; Shi, W.

2012-05-01

Incremental Support vector machine (ISVM) is a new learning method developed in recent years based on the foundations of statistical learning theory. It is suitable for the problem of sequentially arriving field data and has been widely used for product quality prediction and production process optimization. However, the traditional ISVM learning does not consider the quality of the incremental data which may contain noise and redundant data; it will affect the learning speed and accuracy to a great extent. In order to improve SVM training speed and accuracy, a modified incremental support vector machine (MISVM) is proposed in this paper. Firstly, the margin vectors are extracted according to the Karush-Kuhn-Tucker (KKT) condition; then the distance from the margin vectors to the final decision hyperplane is calculated to evaluate the importance of margin vectors, where the margin vectors are removed while their distance exceed the specified value; finally, the original SVs and remaining margin vectors are used to update the SVM. The proposed MISVM can not only eliminate the unimportant samples such as noise samples, but also can preserve the important samples. The MISVM has been experimented on two public data and one field data of zinc coating weight in strip hot-dip galvanizing, and the results shows that the proposed method can improve the prediction accuracy and the training speed effectively. Furthermore, it can provide the necessary decision supports and analysis tools for auto control of product quality, and also can extend to other process industries, such as chemical process and manufacturing process.

Predicting Sediment Thickness on Vanished Ocean Crust Since 200 Ma

NASA Astrophysics Data System (ADS)

Dutkiewicz, A.; Müller, R. D.; Wang, X.; O'Callaghan, S.; Cannon, J.; Wright, N. M.

2017-12-01

Tracing sedimentation through time on existing and vanished seafloor is imperative for constraining long-term eustasy and for calculating volumes of subducted deep-sea sediments that contribute to global geochemical cycles. We present regression algorithms that incorporate the age of the ocean crust and the mean distance to the nearest passive margin to predict sediment thicknesses and long-term decompacted sedimentation rates since 200 Ma. The mean sediment thickness decreases from ˜220 m at 200 Ma to a minimum of ˜140 m at 130 Ma, reflecting the replacement of old Panthalassic ocean floor with young sediment-poor mid-ocean ridges, followed by an increase to ˜365 m at present-day. This increase reflects the accumulation of sediments on ageing abyssal plains proximal to passive margins, coupled with a decrease in the mean distance of any parcel of ocean crust to the nearest passive margin by over 700 km, and a doubling of the total passive margin length at present-day. Mean long-term sedimentation rates increase from ˜0.5 cm/ky at 160 Ma to over 0.8 cm/ky today, caused by enhanced terrigenous sediment influx along lengthened passive margins, superimposed by the onset of ocean-wide carbonate sedimentation. Our predictive algorithms, coupled to a plate tectonic model, provide a framework for constraining the seafloor sediment-driven eustatic sea-level component, which has grown from ˜80 to 210 m since 120 Ma. This implies a long-term sea-level rise component of 130 m, partly counteracting the contemporaneous increase in ocean basin depth due to progressive crustal ageing.

Organic geochemistry of sediments from the continental margin off southern New England, U.S.A.--Part I. Amino acids, carbohydrates and lignin

NASA Technical Reports Server (NTRS)

Steinberg, S. M.; Venkatesan, M. I.; Kaplan, I. R.

1987-01-01

Total organic carbon (TOC), lignin, amino acids, sugars and amino sugars were measured in recent sediments for the continental margin off southern New England. The various organic carbon fractions decreased in concentration with increasing distance from shore. The fraction of the TOC that was accounted for by these major components also decreased with increasing distance from shore. The concentration of lignin indicated that only about 3-5% of the organic carbon in the nearshore sediment was of terrestrial origin. The various fractions were highly correlated, which was consistent with a simple linear mixing model of shelf organic matter with material form the slope and rise and indicated a significant transport of sediment from the continental shelf to the continental slope and rise.

Botulinum Toxin as an Alternative to Treat the Spasm of the Near Reflex.

PubMed

Laria, Carlos; Merino-Suárez, María L; Piñero, David P; Gómez-Hurtado, Arantxa; Pérez-Cambrodí, Rafael J

2015-01-01

We describe the case of an eight-year-old girl with complaints of headaches and blurred vision (uncorrected visual acuity: 0.1 decimal) that showed on examination miotic pupils, pseudomyopia, no ocular motility restrictions, and no associated neurological disease. After initial treatment with cyclopentolate for two months, pseudomyopia persisted with an intermittent and variable esotropia. Spectacles of +1 both eyes and atropine 1% one drop daily were then prescribed. The situation improved and remained stable for several weeks, with pseudomyopia and esotropia reappearing later. Finally, botulinum toxin (2.5 iu Botox) was injected in the medial rectus muscle on two occasions and a visual therapy program based on the stimulation of fusional divergence, diplopia, and stereopsis consciousness was recommended. This prescription was combined with the use of atropine during the first few weeks. Orthotropia and corrected distance visual acuity of 1.0 were found three months after treatment. The evolution and clinical results of this case report suggest that botulinum toxin in combination with other therapeutic alternatives may be useful in the treatment of spasm of the near reflex.

Primate translational vestibuloocular reflexes. III. Effects of bilateral labyrinthine electrical stimulation

NASA Technical Reports Server (NTRS)

Angelaki, D. E.; McHenry, M. Q.; Dickman, J. D.; Perachio, A. A.

2000-01-01

The effects of functional, reversible ablation and potential recruitment of the most irregular otolith afferents on the dynamics and sensitivity of the translational vestibuloocular reflexes (trVORs) were investigated in rhesus monkeys trained to fixate near and far targets. Translational motion stimuli consisted of either steady-state lateral and fore-aft sinusoidal oscillations or short-lasting transient lateral head displacements. Short-duration (usually <2 s) anodal (inhibitory) and cathodal (excitatory) currents (50-100 microA) were delivered bilaterally during motion. In the presence of anodal labyrinthine stimulation, trVOR sensitivity and its dependence on viewing distance were significantly decreased. In addition, anodal currents significantly increased phase lags. During transient motion, anodal stimulation resulted in significantly lower initial eye acceleration and more sluggish responses. Cathodal currents tended to have opposite effects. The main characteristics of these results were simulated by a simple model where both regularly and irregularly discharging afferents contribute to the trVORs. Anodal labyrinthine currents also were found to decrease eye velocity during long-duration, constant velocity rotations, although results were generally more variable compared with those during translational motion.

[Portfolio in nursing school: myth or reality].

PubMed

Garnier, Chantal; Marchand, Claire

2012-09-01

The portfolio is a new tool that has been introduced for the setting up of a new program concerning the nurse training. It aims at the would-be nurse to improve their self-reliance and make them assess themselves through a critical and reflexive approach. Indeed, the portfolio is mostly made up of sheets that the student has to fill in when describing and analysing several professional conditions. This study is about the assessment of the relevance in the portfolio that each nurse student owns in order to make them improve their reflexive practical. The work will, thus, suggest different ways of thinking and improving the use of the tool. 30 portfolios were chosen randomly among the 2nd year students, because 180 analysis were assessed thanks to a grid. 10 viewpoints from volunteer students were gathered after several semi directive interviews. The qualitative and evaluative analysis shows that the students develop the reflexive practical throughout their trainings. It seems, indeed, relevant to choose the portfolio in order to help the students to develop this way of working. According to them, there are several positive points such as the distance towards an event, an awareness-raising of the acquisition, feedbacks about the quality of the text by the trainer and an ability to assess oneself. Yet, even though it was created 18 months ago, there are some limits such as the too short period of mentoring and feedback, the lack of time for the students to write their analysis, the fact that it is not a practical tool, and the unclear description of assessment criteria. In order to fulfil the needs, some solutions are to be found. The portfolio is clearly helpful for the students who wish to increase/improve gradually their reflexive practice. Thus, the trainer's role is crucial, when he is a supervisor.

Optical modeling of a corneal inlay in real eyes to increase depth of focus: optimum centration and residual defocus.

PubMed

Tabernero, Juan; Artal, Pablo

2012-02-01

To determine the optimum position to center a small-aperture corneal inlay and the effect of residual defocus in the surgical eye to maximize depth of focus. Laboratorio de Óptica, Universidad de Murcia, Murcia, Spain. Cohort study. Personalized eye models were built using actual data (corneal topography, eye length, ocular aberrations, and eye alignment). A small aperture 1.6 mm in diameter was placed at the corneal plane in each model. The monochromatic and polychromatic Strehl ratios were calculated as a function of the pinhole position. Different residual defocus values were also incorporated into the models, and the through-focus Strehl ratios were calculated. Sixteen eye models were built. For most subjects, the optimum location of the aperture for distance vision was close to the corneal reflex position. For a given optimized centration of the aperture, the best compromise of depth of focus was obtained when the eyes had some residual myopic defocus (range -0.75 to -1.00 diopter [D]). Strehl ratio values were over 0.1 for far distance, which led to visual acuities better than 20/20. The depth of focus was 2.50 D with a mean near visual acuity of Jaeger 1 or better. In eyes with little astigmatism and aberrations, the optimum centration of the small aperture was near the corneal reflex position. To improve optical outcomes with the inlay, some small residual myopia and correction of corneal astigmatism might be required. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Defining the surgical margins of adenoid cystic carcinoma and their impact on outcome: An international collaborative study.

PubMed

Amit, Moran; Na'ara, Shorook; Trejo-Leider, Leonor; Ramer, Naomi; Burstein, David; Yue, Ma; Miles, Brett; Yang, Xinjie; Lei, Delin; Bjoerndal, Kristine; Godballe, Christian; Mücke, Thomas; Wolff, Klaus-Dietrich; Eckardt, André M; Copelli, Chiara; Sesenna, Enrico; Patel, Snehal; Ganly, Ian; Gil, Ziv

2017-05-01

The mainstay of treatment in adenoid cystic carcinoma (ACC) of the head and neck is surgical resection with negative margins. The purpose of this study was to define the margin status that associates with survival outcomes of ACC of the head and neck. We conducted univariate and multivariate analyses of international data. Data of 507 patients with ACC of the head and neck were analyzed; negative margins defined as ≥5 mm were detected in 253 patients (50%). On multivariate analysis, the hazard ratios (HRs) of positive margin status were 2.68 (95% confidence interval [CI], 1.2-6.2; p = .04) and 2.63 (95% CI, 1.1-6.3; p = .03) for overall survival (OS) and disease-specific survival (DSS), respectively. Close margins had no significant impact on outcome, with HRs of 1.1 (95% CI, 0.4-3.0; p = .12) and 1.07 (95% CI, 0.3-3.4; p = .23) for OS and DSS, respectively, relative with negative margins. In head and neck ACC, positive margins are associated with the worst outcome. Negative or close margins are associated with improved outcome, regardless of the distance from the tumor. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1008-1014, 2017. © 2017 Wiley Periodicals, Inc.

Prevalence and predictive factors for the detection of carcinoma in cavity margin performed at the time of breast lumpectomy.

PubMed

Tengher-Barna, Iulia; Hequet, Delphine; Reboul-Marty, Jeanne; Frassati-Biaggi, Annonciade; Seince, Nathalie; Rodrigues-Faure, Anabela; Uzan, Michèle; Ziol, Marianne

2009-02-01

Margin resection status is a major risk factor for the development of local recurrence in breast conservation therapy for carcinoma. Tumor bed excision sent as separate orientated cavity margins represents a tool to verify the completeness of the carcinoma resection. We aimed to (1) determine the prevalence of positive cavity margin and its influence on subsequent surgical treatment and (2) identify potential predictive factors for positive cavity margins. From 2003 to 2006, 107 (57 years; 30-88) consecutive patients who underwent a lumpectomy for carcinoma with four orientated cavity margins for carcinoma were selected. Preoperative clinical, radiological and histological data, perioperative macroscopic characteristics and definitive histological analysis results were recorded. Lumpectomy or cavity margins were considered as positive when the distance from carcinoma to the margin was less than or equal to 3 mm. Histological examination of cavity margins showed carcinoma in 38 patients (35%), therefore modifying subsequent surgical therapy in 33 cases. Examination of the cavity margins led (1) to avoiding surgical re-excision in 20 cases (lumpectomy margins were positive and the cavity margins negative), (2) to performing a mastectomy or a re-excision in 13 cases (carcinoma was detected in the cavity margins although the lumpectomy margins were negative or tumor size was superior to 3 cm). Between preoperative and perioperative parameters, US scan and macroscopic size of the tumor were predictive factors for positive cavity margins whereas characteristics of the carcinoma determined on biopsy samples and macroscopic status of the lumpectomy margins were not. Our study confirms that the systematic practice of cavity margin resection avoids surgical re-excision and reduces the likelihood of underestimating the extent of the tumor.

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

PubMed

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.

Variability in Hoffmann and tendon reflexes in healthy male subjects

NASA Technical Reports Server (NTRS)

Good, E.; Do, S.; Jaweed, M.

1992-01-01

There is a time dependent decrease in amplitude of H- and T-reflexes during Zero-G exposure and subsequently an increase in the amplitude of the H-reflex 2-4 hours after return to a 1-G environment. These alterations have been attributed to the adaptation of the human neurosensory system to gravity. The Hoffman reflex (H-reflex) is an acknowledged method to determine the integrity of the monosynaptic reflex arc. However deep tendon reflexes (DTR's or T-reflexes), elicited by striking the tendon also utilize the entire reflex arc. The objective of this study was to compare the variability in latency and amplitude of the two reflexes in healthy subjects. Methods: Nine healthy male subjects, 27-43 years in age, 161-175 cm in height plus 60-86 Kg in weight, underwent weekly testing for four weeks with a Dan-Tec EMG counterpoint EMG system. Subjects were studied prone and surface EMG electrodes were placed on the right and left soleus muscles. The H-reflex was obtained by stimulating the tibial nerve in the politeal fossa with a 0.2 msec square wave pulse delivered at 2 Hz until the maximum H-reflex was obtained. The T-reflex was invoked by tapping the achilles tendon with a self triggering reflex hammer connected to the EMG system. The latencies and amplitudes for the H- and T-reflexes were measured. Results: These data indicate that the amplitudes of these reflexes varied considerably. However, latencies to invoked responses were consistent. The latency of the T-reflex was approximately 3-5 msec longer than the H-reflex. Conclusion: The T-reflex is easily obtained, requires less time, and is more comfortable to perform. Qualitative data can be obtained by deploying self triggering, force plated reflex hammers both in the 1-G and Zero-G environment.

Star-planet interactions. IV. Possibility of detecting the orbit-shrinking of a planet around a red giant

NASA Astrophysics Data System (ADS)

Meynet, Georges; Eggenberger, Patrick; Privitera, Giovanni; Georgy, Cyril; Ekström, Sylvia; Alibert, Yann; Lovis, Christophe

2017-06-01

The surface rotations of some red giants are so fast that they must have been spun up by tidal interaction with a close companion, either another star, a brown dwarf, or a planet. We focus here on the case of red giants that are spun up by tidal interaction with a planet. When the distance between the planet and the star decreases, the spin period of the star decreases, the orbital period of the planet decreases, and the reflex motion of the star increases. We study the change rate of these three quantities when the circular orbit of a planet of 15 MJ that initially orbits a 2 M⊙ star at 1 au shrinks under the action of tidal forces during the red giant phase. We use stellar evolution models coupled with computations of the orbital evolution of the planet, which allows us to follow the exchanges of angular momentum between the star and the orbit in a consistent way. We obtain that the reflex motion of the red giant star increases by more than 1 m s-1 per year in the last 40 yr before the planet engulfment. During this phase, the reflex motion of the star is between 660 and 710 m s-1. The spin period of the star increases by more than about 10 min per year in the last 3000 yr before engulfment. During this period, the spin period of the star is shorter than 0.7 yr. During this same period, the variation in orbital period, which is shorter than 0.18 yr, is on the same order of magnitude. Changes in reflex-motion and spin velocities are very small and thus most likely out of reach of being observed. The most promising way of detecting this effect is through observations of transiting planets, that is, through changes of the beginning or end of the transit. For the relatively long orbital periods expected around red giants, long observing runs of typically a few years are needed. Interesting star-planet systems that currently are in this stage of orbit-shrinking would be red giants with fast rotation (above typically 4-5 km s-1), a low surface gravity (log g lower than 2), and having a planet at a distance typically smaller than about 0.4-1 au, depending on log g. A space mission like PLATO might be of great interest for detecting planets that are on the verge of being engulfed by red giants. The discovery of a few systems, even only one, would provide very interesting clues about the physics of tidal interaction between a red giant and a planet.

Resistor-logic demultiplexers for nanoelectronics based on constant-weight codes.

PubMed

Kuekes, Philip J; Robinett, Warren; Roth, Ron M; Seroussi, Gadiel; Snider, Gregory S; Stanley Williams, R

2006-02-28

The voltage margin of a resistor-logic demultiplexer can be improved significantly by basing its connection pattern on a constant-weight code. Each distinct code determines a unique demultiplexer, and therefore a large family of circuits is defined. We consider using these demultiplexers for building nanoscale crossbar memories, and determine the voltage margin of the memory system based on a particular code. We determine a purely code-theoretic criterion for selecting codes that will yield memories with large voltage margins, which is to minimize the ratio of the maximum to the minimum Hamming distance between distinct codewords. For the specific example of a 64 × 64 crossbar, we discuss what codes provide optimal performance for a memory.

M-Isomap: Orthogonal Constrained Marginal Isomap for Nonlinear Dimensionality Reduction.

PubMed

Zhang, Zhao; Chow, Tommy W S; Zhao, Mingbo

2013-02-01

Isomap is a well-known nonlinear dimensionality reduction (DR) method, aiming at preserving geodesic distances of all similarity pairs for delivering highly nonlinear manifolds. Isomap is efficient in visualizing synthetic data sets, but it usually delivers unsatisfactory results in benchmark cases. This paper incorporates the pairwise constraints into Isomap and proposes a marginal Isomap (M-Isomap) for manifold learning. The pairwise Cannot-Link and Must-Link constraints are used to specify the types of neighborhoods. M-Isomap computes the shortest path distances over constrained neighborhood graphs and guides the nonlinear DR through separating the interclass neighbors. As a result, large margins between both interand intraclass clusters are delivered and enhanced compactness of intracluster points is achieved at the same time. The validity of M-Isomap is examined by extensive simulations over synthetic, University of California, Irvine, and benchmark real Olivetti Research Library, YALE, and CMU Pose, Illumination, and Expression databases. The data visualization and clustering power of M-Isomap are compared with those of six related DR methods. The visualization results show that M-Isomap is able to deliver more separate clusters. Clustering evaluations also demonstrate that M-Isomap delivers comparable or even better results than some state-of-the-art DR algorithms.

JANNAF Lessons Learned Panel Discussion

NASA Technical Reports Server (NTRS)

Richards, Steve

2010-01-01

The difference between the AS-510 observed and predicted separation distance is attributed to a greater F-1 engine "tail off" impulse than that used in the separation distance prediction. . The F-1 thrust decay was normal and not appreciably different from previous (AS-505 through 509) flights. . Analysis indicates that with an S-IC stage having only four retro motors, failure of one retro motor to ignite would result in marginal separation distances and, in the 3-sigma case, re-contact of the two stages. . S-IC-11 and subsequent flight stages were equipped with eight retro motors rather than the planned four.

Role of tumour-free margin distance for loco-regional control in vulvar cancer-a subset analysis of the Arbeitsgemeinschaft Gynäkologische Onkologie CaRE-1 multicenter study.

PubMed

Woelber, Linn; Griebel, Lis-Femke; Eulenburg, Christine; Sehouli, Jalid; Jueckstock, Julia; Hilpert, Felix; de Gregorio, Nikolaus; Hasenburg, Annette; Ignatov, Atanas; Hillemanns, Peter; Fuerst, Sophie; Strauss, Hans-Georg; Baumann, Klaus H; Thiel, Falk C; Mustea, Alexander; Meier, Werner; Harter, Philipp; Wimberger, Pauline; Hanker, Lars Christian; Schmalfeldt, Barbara; Canzler, Ulrich; Fehm, Tanja; Luyten, Alexander; Hellriegel, Martin; Kosse, Jens; Heiss, Christoph; Hantschmann, Peer; Mallmann, Peter; Tanner, Berno; Pfisterer, Jacobus; Richter, Barbara; Neuser, Petra; Mahner, Sven

2016-12-01

A tumour-free pathological resection margin of ≥8 mm is considered state-of-the-art. Available evidence is based on heterogeneous cohorts. This study was designed to clarify the relevance of the resection margin for loco-regional control in vulvar cancer. AGO-CaRE-1 is a large retrospective study. Patients (n = 1618) with vulvar cancer ≥ FIGO stage IB treated at 29 German gynecologic-cancer-centres 1998-2008 were included. This subgroup analysis focuses on solely surgically treated node-negative patients with complete tumour resection (n = 289). Of the 289 analysed patients, 141 (48.8%) had pT1b, 140 (48.4%) pT2 and 8 (2.8%) pT3 tumours. One hundred twenty-five (43.3%) underwent complete vulvectomy, 127 (43.9%) partial vulvectomy and 37 (12.8%) radical local excision. The median minimal resection margin was 5 mm (1 mm-33 mm); all patients received groin staging, in 86.5% with full dissection. Median follow-up was 35.1 months. 46 (15.9%) patients developed recurrence, thereof 34 (11.8%) at the vulva, after a median of 18.3 months. Vulvar recurrence rates were 12.6% in patients with a margin <8 mm and 10.2% in patients with a margin ≥8 mm. When analysed as a continuous variable, the margin distance had no statistically significant impact on local recurrence (HR per mm increase: 0.930, 95% CI: 0.849-1.020; p = 0.125). Multivariate analyses did also not reveal a significant association between the margin and local recurrence neither when analysed as continuous variable nor categorically based on the 8 mm cutoff. Results were consistent when looking at disease-free-survival and time-to-recurrence at any site (HR per mm increase: 0.949, 95% CI: 0.864-1.041; p = 0.267). The need for a minimal margin of 8 mm could not be confirmed in the large and homogeneous node-negative cohort of the AGO-CaRE database. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dyract compomer: comparison of total etch vs. no etch technique.

PubMed

Kugel, G; Perry, R D; Hoang, E; Hoang, T; Ferrari, M

1998-01-01

Different dental materials and methods can influence the integrity of the marginal seal of restorations. To evaluate the microleakage of Dyract AP Light Cured Compomer, a polyacid modified resin (Caulk), using etched and unetched techniques, standardized trapezoidal Class V restorations were placed on facial or lingual surfaces of 20 human molars with the gingival margin in the cementum. Each restoration was scored at the cervical by two independent, double blinded operators, with reference to the DEJ, for dye penetration on a ranking system of: 0 = no evidence of dye penetration; 1 = dye penetration up to one-half the distance to the axial wall; 2 = dye penetration beyond one-half the distance to the axial wall but short of the axial wall; 3 = dye penetration to the axial wall or beyond. Statistical analysis (Fisher Exact Test) indicated that the etched compomer demonstrated significantly less microleakage when compared to the unetched compomer (p < 0.05).

Customized ultra-high-power toric intraocular lens implantation for pellucid marginal degeneration and cataract.

PubMed

Luck, Jonathan

2010-07-01

I report a case of pellucid marginal degeneration (PMD) with cataract that was successfully treated with implantation of an ultra-high-power customized bitoric AT.Comfort 646TLC intraocular lens (IOL). The preoperative uncorrected distance visual acuity (UDVA) was 6/120 and the corrected distance visual acuity (CDVA), 6/24 with 10.9 diopters (D) of keratometric astigmatism on Scheimpflug imaging. After implantation of an IOL with -0.5 +16.0 x 170, the UDVA was 6/9 with a manifest refraction of +0.25 +1.25 x 150 and the CDVA, 6/6(-1). No surgical complications or postoperative problems occurred, and the patient was very satisfied with the outcome. A longer follow-up is required to confirm this favorable clinical result. The author has no financial or proprietary interest in any material or method mentioned. Copyright 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Holocene re-colonisation, central-marginal distribution and habitat specialisation shape population genetic patterns within an Atlantic European grass species.

PubMed

Harter, D E V; Jentsch, A; Durka, W

2015-05-01

Corynephorus canescens (L.) P.Beauv. is an outbreeding, short-lived and wind-dispersed grass species, highly specialised on scattered and disturbance-dependent habitats of open sandy sites. Its distribution ranges from the Iberian Peninsula over Atlantic regions of Western and Central Europe, but excludes the two other classical European glacial refuge regions on the Apennine and Balkan Peninsulas. To investigate genetic patterns of this uncommon combination of ecological and biogeographic species characteristics, we analysed AFLP variation among 49 populations throughout the European distribution range, expecting (i) patterns of SW European glacial refugia and post-glacial expansion to the NE; (ii) decreasing genetic diversity from central to marginal populations; and (iii) interacting effects of high gene flow and disturbance-driven genetic drift. Decreasing genetic diversity from SW to NE and distinct gene pool clustering imply refugia on the Iberian Peninsula and in western France, from where range expansion originated towards the NE. High genetic diversity within and moderate genetic differentiation among populations, and a significant pattern of isolation-by-distance indicate a gene flow drift equilibrium within C. canescens, probably due to its restriction to scattered and dynamic habitats and limited dispersal distances. These features, as well as the re-colonisation history, were found to affect genetic diversity gradients from central to marginal populations. Our study emphasises the need for including the specific ecology into analyses of species (re-)colonisation histories and range centre-margin analyses. To account for discontinuous distributions, new indices of marginality were tested for their suitability in studies of centre-periphery gradients. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

Mohs micrographic surgery in dermatofibrosarcoma protuberans allows tumour clearance with smaller margins and greater preservation of healthy tissue compared with conventional surgery: a study of 74 primary cases.

PubMed

Serra-Guillén, C; Llombart, B; Nagore, E; Guillén, C; Requena, C; Traves, V; Kindem, S; Alcalá, R; Rivas, N; Sanmartín, O

2015-01-01

Dermatofibrosarcoma protuberans (DFSP) is an uncommon skin tumour with aggressive local growth. Whether DFSP should be treated with conventional surgery (CS) or Mohs micrographic surgery (MMS) has long been a topic of debate. To calculate, in a large series of DFSP treated by MMS, the minimum margin that would have been needed to achieve complete clearance by CS. Secondly, to calculate the percentage of healthy tissue that was preserved by MMS rather than CS with 2- and 3-cm margins. The minimum margin was calculated by measuring the largest distance from the visible edge of the tumour to the edge of the definitive surgical defect. Tumour and surgical defect areas for hypothetical CS with 2- and 3-cm margins were calculated using AutoCAD for Windows. A mean minimum margin of 1·34 cm was required to achieve complete clearance for the 74 tumours analysed. The mean percentages of skin spared using MMS rather than CS with 2- and 3-cm margins were 49·4% and 67·9%, respectively. MMS can achieve tumour clearance with smaller margins and greater preservation of healthy tissue than CS. © 2014 British Association of Dermatologists.

Impact of margin status and lymphadenectomy on clinical outcomes in resected pancreatic adenocarcinoma: implications for adjuvant radiotherapy.

PubMed

Osipov, Arsen; Naziri, Jason; Hendifar, Andrew; Dhall, Deepti; Rutgers, Joanne K; Chopra, Shefali; Li, Quanlin; Tighiouart, Mourad; Annamalai, Alagappan; Nissen, Nicholas N; Tuli, Richard

2016-04-01

Adjuvant chemoradiotherapy (CRT) in the treatment of pancreatic ductal adenocarcinoma (PDA) is controversial. Minimal data exists regarding the clinical significance of margin clearance distance and lymph node (LN) parameters, such as extent of dissection and LN ratio. We assessed the impact of these variables on clinical outcomes to more clearly define the subset of patients who may benefit from adjuvant radiotherapy (RT). We identified 106 patients with resected stage 1-3 PDA from 2007-2013. Resection margins were categorized as positive (tumor at ink), ≤1, or >1 mm. LN evaluation included total number examined (NE), number of positive nodes (NP), ratio of NP to NE (NR), extent of dissection, and positive periportal LNs. The impact of these variables was assessed on disease-free survival (DFS) and overall survival (OS) using multivariate cox proportional hazards modeling. In patients receiving adjuvant chemotherapy (CT) alone, greater margin clearance led to improved DFS (P=0.0412, HR =0.51). Range of NE was 4-37, with a mean of 19. NE was not associated with DFS or OS, yet absolute NP of 5 or more was associated with a significantly worse DFS (P=0.005). Whereas periportal lymphadenectomy did not result in improved DFS or OS, patients with positive periportal LN had worse clinical outcomes (DFS, P=0.0052; OS, P=0.023). The use of adjuvant CRT was associated with improved OS (P=0.049; HR=0.29). In patients receiving adjuvant CT alone, there was a clinically significant benefit to clearing the surgical margin beyond tumor at ink. Having ≥5 NP and positive periportal LN led to significantly worse clinical outcomes. The addition of adjuvant RT to CT in resected PDA improved OS. A comprehensive evaluation of resection margin distance and LN parameters may identify more patients at risk for locoregional failure who may benefit from adjuvant CRT.

Impact of margin status and lymphadenectomy on clinical outcomes in resected pancreatic adenocarcinoma: implications for adjuvant radiotherapy

PubMed Central

Osipov, Arsen; Naziri, Jason; Hendifar, Andrew; Dhall, Deepti; Rutgers, Joanne K.; Chopra, Shefali; Li, Quanlin; Tighiouart, Mourad; Annamalai, Alagappan; Nissen, Nicholas N.

2016-01-01

Background Adjuvant chemoradiotherapy (CRT) in the treatment of pancreatic ductal adenocarcinoma (PDA) is controversial. Minimal data exists regarding the clinical significance of margin clearance distance and lymph node (LN) parameters, such as extent of dissection and LN ratio. We assessed the impact of these variables on clinical outcomes to more clearly define the subset of patients who may benefit from adjuvant radiotherapy (RT). Methods We identified 106 patients with resected stage 1-3 PDA from 2007-2013. Resection margins were categorized as positive (tumor at ink), ≤1, or >1 mm. LN evaluation included total number examined (NE), number of positive nodes (NP), ratio of NP to NE (NR), extent of dissection, and positive periportal LNs. The impact of these variables was assessed on disease-free survival (DFS) and overall survival (OS) using multivariate cox proportional hazards modeling. Results In patients receiving adjuvant chemotherapy (CT) alone, greater margin clearance led to improved DFS (P=0.0412, HR =0.51). Range of NE was 4-37, with a mean of 19. NE was not associated with DFS or OS, yet absolute NP of 5 or more was associated with a significantly worse DFS (P=0.005). Whereas periportal lymphadenectomy did not result in improved DFS or OS, patients with positive periportal LN had worse clinical outcomes (DFS, P=0.0052; OS, P=0.023). The use of adjuvant CRT was associated with improved OS (P=0.049; HR=0.29). Conclusions In patients receiving adjuvant CT alone, there was a clinically significant benefit to clearing the surgical margin beyond tumor at ink. Having ≥5 NP and positive periportal LN led to significantly worse clinical outcomes. The addition of adjuvant RT to CT in resected PDA improved OS. A comprehensive evaluation of resection margin distance and LN parameters may identify more patients at risk for locoregional failure who may benefit from adjuvant CRT. PMID:27034792

National Rugby League athletes and tendon tap reflex assessment: a matched cohort clinical study.

PubMed

Maurini, James; Ohmsen, Paul; Condon, Greg; Pope, Rodney; Hing, Wayne

2016-11-04

Limited research suggests elite athletes may differ from non-athletes in clinical tendon tap reflex responses. In this matched cohort study, 25 elite rugby league athletes were compared with 29 non-athletes to examine differences in tendon reflex responses. Relationships between reflex responses and lengths of players' careers were also examined. Biceps, triceps, patellar and Achilles tendon reflexes were clinically assessed. Right and left reflexes were well correlated for each tendon (r S  = 0.7-0.9). The elite rugby league athletes exhibited significantly weaker reflex responses than non-athletes in all four tendons (p < 0.005). Biceps reflexes demonstrated the largest difference and Achilles reflexes the smallest difference. Moderate negative correlations (r S  = -0.3-0.6) were observed between reflex responses and lengths of players' careers. Future research is required to further elucidate mechanisms resulting in the observed differences in tendon reflexes and to ensure clinical tendon tap examinations and findings can be interpreted appropriately in this athletic population.

Lower Eyelid Retraction Surgery Without Internal Spacer Graft.

PubMed

Taban, Mehryar Ray

2017-02-01

Internal eyelid spacer graft is routinely placed during lower eyelid retraction surgery, which may be unnecessary. To evaluate the efficacy of lower eyelid retraction surgery without internal graft in select cases. Retrospective analysis of patients undergoing reconstructive lower eyelid retraction surgery without internal graft, by one surgeon from 2013 to 2015. Surgical technique included transconjunctival lower eyelid retractor lysis, canthoplasty, and temporary tarsorrhaphy, with or without subperiosteal midface-sub oribularis oculi fat (SOOF) lifting and scar lysis. Eyelids with true lower eyelid middle-lamella shortage were excluded. Analysis included 17 surgeries (11 patients). Eight of 11 patients had undergone at least one previous lower eyelid surgery with resultant lower eyelid retraction and sclera show. Preoperative and postoperative photographs at longest follow-up visit were analyzed with standardized measurements. Patient satisfaction was recorded using questionnaire. Etiologies of lower eyelid retraction included prior lower blepharoplasty, thyroid eye disease, and chronic facial palsy. All 11 patients (17 procedures) demonstrated improvement of lower eyelid position. The mean improvement of marginal reflex distance was 2.2 mm (range, 1.6-2.8 mm). There was one case of mild overcorrection. The average follow-up was 7 months (range, 6 months-2 years). Midface lift was performed for 14 of 17 eyelids. This study demonstrates improvement of lower lid position after lower eyelid retraction surgery without internal eyelid spacer graft in select patients. Most patients in our study had undergone previous lower eyelid blepharoplasty and required midface-SOOF lifting. The author proposes that "routine" placement of lower eyelid internal spacer/graft may not be necessary during lower eyelid retraction surgery. © 2016 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

The success rate of TED upper eyelid retraction reoperations.

PubMed

Golan, Shani; Rootman, Dan B; Goldberg, Robert A

2016-12-01

Although reoperation rates for upper lid retraction surgery for thyroid eye disease (TED) typically range between 8% and 23%, there is little literature describing the outcomes of these second operations. In this retrospective observational cohort study, all patients that underwent surgery for upper eyelid retraction over a 14-year period at a single institution were included. Cases were included if a second eyelid retraction surgery was performed during the study period. Success of surgery was defined as a marginal reflex distance (MRD1) of 2.5 to 4.5 mm in each eye and less than 1 mm difference in MRD1 between the eyes. Overcorrection and undercorrection were defined as above and below these bounds, respectively. 72 eyes in 49 patients were included in the study. The mean age was 56.6 (±11.5) years. By definition, all patients had at least 1 lid lengthening surgery for upper eyelid retraction, and at least 1 subsequent surgery. For this second surgery, 61 eyes (85%) underwent retraction surgery and 11 eyes (15%) underwent ptosis surgery. After this second operation, 31% were undercorrected and 33% were overcorrected. A third surgery was performed in 19 eyes (25%), 12 had surgery for residual retraction and 7 for ptosis. After the third operation 10% of eyes were under corrected and 11% were over corrected. Four patients underwent a fourth surgery: one for retraction and three for ptosis. Success was noted in 35% after the second surgery and 44% after the third. Surgical success in eyelid retraction surgery increases from a second to a third consecutive surgery, and residual asymmetry was roughly equally distributed between over- and undercorrection.

Bovine Acellular Dermal Matrix for Levator Lengthening in Thyroid-Related Upper-Eyelid Retraction.

PubMed

Sun, Jing; Liu, Xingtong; Zhang, Yidan; Huang, Yazhuo; Zhong, Sisi; Fang, Sijie; Zhuang, Ai; Li, Yinwei; Zhou, Huifang; Fan, Xianqun

2018-05-02

BACKGROUND Eyelid retraction is the most common and often the first sign of thyroid eye disease (TED). Upper-eyelid retraction causes both functional and cosmetic problems. In order to correct the position of the upper eyelid, surgery is required. Many procedures have demonstrated good outcomes in mild and moderate cases; however, unpredictable results have been obtained in severe cases. Dryden introduced an upper-eyelid-lengthening procedure, which used scleral grafts, but outcomes were unsatisfactory. A new technique is introduced in this study as a reasonable alternative for TED-related severe upper-eyelid retraction correction. MATERIAL AND METHODS An innovative technique for levator lengthening using bovine acellular dermal matrix as a spacer graft is introduced for severe upper-eyelid retraction secondary to TED. Additionally, 2 modifications were introduced: the fibrous cords scattered on the surface of the levator aponeurosis were excised and the orbital fat pad anterior to the aponeurosis was dissected and sutured into the skin closure in a "skin-tarsus-fat-skin" fashion. RESULTS The modified levator-lengthening surgery was performed on 32 eyelids in 26 patients consisting of 21 women and 5 men (mean age, 37.8 years; age range, 19-67 years). After corrective surgery, the average upper margin reflex distance was lowered from 7.7±0.85 mm to 3.3±0.43 mm. Eighteen cases (69%) had perfect results, while 6 cases (23%) had acceptable results. CONCLUSIONS A modified levator-lengthening procedure using bovine acellular dermal matrix as a spacer graft ameliorated both the symptoms and signs of severe upper-eyelid retraction secondary to TED. This procedure is a reasonable alternative for correction of TED-related severe upper-eyelid retraction.

Bovine Acellular Dermal Matrix for Levator Lengthening in Thyroid-Related Upper-Eyelid Retraction

PubMed Central

Sun, Jing; Liu, Xingtong; Zhang, Yidan; Huang, Yazhuo; Zhong, Sisi; Fang, Sijie; Zhuang, Ai; Li, Yinwei; Zhou, Huifang

2018-01-01

Background Eyelid retraction is the most common and often the first sign of thyroid eye disease (TED). Upper-eyelid retraction causes both functional and cosmetic problems. In order to correct the position of the upper eyelid, surgery is required. Many procedures have demonstrated good outcomes in mild and moderate cases; however, unpredictable results have been obtained in severe cases. Dryden introduced an upper-eyelid-lengthening procedure, which used scleral grafts, but outcomes were unsatisfactory. A new technique is introduced in this study as a reasonable alternative for TED-related severe upper-eyelid retraction correction. Material/Methods An innovative technique for levator lengthening using bovine acellular dermal matrix as a spacer graft is introduced for severe upper-eyelid retraction secondary to TED. Additionally, 2 modifications were introduced: the fibrous cords scattered on the surface of the levator aponeurosis were excised and the orbital fat pad anterior to the aponeurosis was dissected and sutured into the skin closure in a “skin-tarsus-fat-skin” fashion. Results The modified levator-lengthening surgery was performed on 32 eyelids in 26 patients consisting of 21 women and 5 men (mean age, 37.8 years; age range, 19–67 years). After corrective surgery, the average upper margin reflex distance was lowered from 7.7±0.85 mm to 3.3±0.43 mm. Eighteen cases (69%) had perfect results, while 6 cases (23%) had acceptable results. Conclusions A modified levator-lengthening procedure using bovine acellular dermal matrix as a spacer graft ameliorated both the symptoms and signs of severe upper-eyelid retraction secondary to TED. This procedure is a reasonable alternative for correction of TED-related severe upper-eyelid retraction. PMID:29718902

The Phenylephrine Test Revisited.

PubMed

Barsegian, Arpine; Botwinick, Adam; Reddy, Harsha S

To characterize the phenylephrine test in ptotic patients to help clinicians perform the test more efficiently. Adults with involutional ptosis (n = 24, 30 eyes) were assessed with digital photographs for response to topical 2.5% phenylephrine drop instillation. Patient characteristics (age, gender, iris color, dermatochalasis, brow ptosis, and baseline marginal reflex distance-1 [MRD-1] height) were recorded. From the photographs, change in (MRD-1), presence of conjunctival blanching, pupillary dilation, and Hering effect were recorded at specified time intervals, 1 minute to 1 hour after drop placement. Correlations between patient characteristics and measured outcomes were evaluated using analysis of variance, Pearson coefficient, or chi-square tests. The authors found that 73% of eyes had eyelid elevation with phenylephrine. Of these, 50% reached maximal eyelid elevation by 5 minutes, and 86% by 10 minutes after drop placement, but 14% did not reach maximal MRD-1 until 30 minutes. There is a negative correlation between the maximum MRD-1 and the baseline MRD-1 eyelid height (r = -0.5330, p < 0.01). There is no significant relationship between time to pupillary dilation with either time to max eyelid elevation or max eyelid elevation. No patient characteristic studied affected the likelihood of eyelid response to phenylephrine or presence of Hering effect. Although most ptotic eyelids demonstrate a response to 2.5% phenylephrine within 10 minutes, there is a subset of patients that respond much later. More ptotic eyelids had greater eyelid elevation with phenylephrine. Pupillary dilation and conjunctival blanching are neither predictive of nor temporally associated with eyelid height elevation. The authors did not identify any patient factors (e.g., dermatochalasis, brow ptosis) that can predict the likelihood of response to phenylephrine.

Evaluation of Patients with Facial Palsy and Ophthalmic Sequelae: A 23-Year Retrospective Review.

PubMed

Joseph, Shannon S; Joseph, Andrew W; Smith, Jane I; Niziol, Leslie M; Musch, David C; Nelson, Christine C

2017-10-01

Facial palsy (FP) can result in serious ophthalmic sequelae including loss of vision. We describe the clinical characteristics of FP patients presenting for ophthalmologic evaluation and the timing for initiating ophthalmologic care. We performed a retrospective review of 96 consecutive FP patients presenting between 1992 and 2015 at a tertiary eye center. The main outcome measures were time interval from the diagnosis of FP and onset of ocular symptoms to the initial ophthalmologic evaluation (IOE), and the severity of exposure keratopathy and eyelid malposition on IOE. The median time interval from the diagnosis of FP to the IOE was 1.6 years (interquartile range; IQR = 0.5-9.2), and from the onset of ocular symptoms to IOE was 0.8 years (IQR = 0.3-2.3). The most common ocular symptoms were dryness (47.9%; n = 46), irritation (39.6%; n = 38), and tearing (30.2%; n = 29). A total of 26.0% (n = 25) of patients were bothered by the appearance of their eyes. Only 13.5% (n = 13) noted change in vision. On IOE, 81.6% (n = 75) of patients had punctate epithelial erosions (PEE), of which 52.3% (n = 35) had moderate to severe PEE, 3.3% (n = 3) had corneal ulcers and 2.2% (n = 2) had corneal abrasions. The average margin-reflex distance 2 was 6.4 mm (SD = 2.4) with average lagophthalmos of 3.5 mm (SD = 3.1). Among FP patients presenting for ophthalmologic evaluation, exposure keratopathy (as evidenced by PEE and corneal ulcers/abrasions) is highly prevalent and moderately severe on IOE, despite only 13.5% of patients noting decreased vision. These findings underscore the importance of timely and thorough ophthalmologic evaluation of FP patients.

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

PubMed

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.

[H reflex in patients with spastic quadriplegia].

PubMed

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.

Shifting Sand in Herschel Crater

NASA Image and Video Library

2011-11-17

The eastern margin of a rippled dune in Herschel Crater on Mars moved an average distance of three meters about three yards between March 3, 2007 and December 1, 2010, in one of two images taken by NASA Mars Reconnaissance Orbiter.

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.

PubMed

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.

Vestibular activation of sympathetic nerve activity

NASA Technical Reports Server (NTRS)

Ray, C. A.; Carter, J. R.

2003-01-01

AIM: The vestibulosympathetic reflex refers to sympathetic nerve activation by the vestibular system. Animal studies indicate that the vestibular system assists in blood pressure regulation during orthostasis. Although human studies clearly demonstrate activation of muscle sympathetic nerve activity (MSNA) during engagement of the otolith organs, the role of the vestibulosympathetic reflex in maintaining blood pressure during orthostasis is not well-established. Examination of the vestibulosympathetic reflex with other cardiovascular reflexes indicates that it is a powerful and independent reflex. Ageing, which is associated with an increased risk for orthostatic hypotension, attenuates the vestibulosympathetic reflex. The attenuated reflex is associated with a reduction in arterial pressure. CONCLUSION: These findings suggest that the vestibulosympathetic reflex assists in blood pressure regulation in humans, but future studies examining this reflex in other orthostatically intolerant populations are necessary to address this hypothesis.

Influence of Meibomian Gland Expression Methods on Human Lipid Analysis Results.

PubMed

Kunnen, Carolina M E; Brown, Simon H J; Lazon de la Jara, Percy; Holden, Brien A; Blanksby, Stephen J; Mitchell, Todd W; Papas, Eric B

2016-01-01

To compare the lipid composition of human meibum across three different meibum expression techniques. Meibum was collected from five healthy non-contact lens wearers (aged 20-35 years) after cleaning the eyelid margin using three meibum expression methods: cotton buds (CB), meibomian gland evaluator (MGE) and meibomian gland forceps (MGF). Meibum was also collected using cotton buds without cleaning the eyelid margin (CBn). Lipids were analyzed by chip-based, nano-electrospray mass spectrometry (ESI-MS). Comparisons were made using linear mixed models. Tandem MS enabled identification and quantification of over 200 lipid species across ten lipid classes. There were significant differences between collection techniques in the relative quantities of polar lipids obtained (P<.05). The MGE method returned smaller polar lipid quantities than the CB approaches. No significant differences were found between techniques for nonpolar lipids. No significant differences were found between cleaned and non-cleaned eyelids for polar or nonpolar lipids. Meibum expression technique influences the relative amount of phospholipids in the resulting sample. The highest amounts of phospholipids were detected with the CB approaches and the lowest with the MGE technique. Cleaning the eyelid margin prior to expression was not found to affect the lipid composition of the sample. This may be a consequence of the more forceful expression resulting in cell membrane contamination or higher risk of tear lipid contamination as a result of reflex tearing. Copyright © 2016 Elsevier Inc. All rights reserved.

On the Second Language Acquisition of Spanish Reflexive Passives and Reflexive Impersonals by French- and English-Speaking Adults

ERIC Educational Resources Information Center

Tremblay, Annie

2006-01-01

This study, a partial replication of Bruhn de Garavito (1999a; 1999b), investigates the second language (L2) acquisition of Spanish reflexive passives and reflexive impersonals by French- and English-speaking adults at an advanced level of proficiency. The L2 acquisition of Spanish reflexive passives and reflexive impersonals by native French and…

Vestibulo-Ocular Reflex to Transient Surge Translation: Complex Geometric Response Ablated by Normal Aging

PubMed Central

Tian, Jun-ru; Mokuno, Eriko; Demer, Joseph L.

2007-01-01

The linear vestibulo-ocular reflex (LVOR) to surge (fore-aft) translation has complex kinematics varying with target eccentricity and distance. To determine normal responses and aging changes, 9 younger [age, 28 ± 2 (SE) yr] and 11 older subjects (age, 69 ± 2 yr) underwent 0.5g whole body surge transients while wearing binocular scleral search coils. Linear chair position and head acceleration were measured with a potentiometer and accelerometer. Subjects viewed centered and 10° horizontally and vertically eccentric targets 50, 25, or 15 cm distant before unpredictable onset of randomly directed surge in darkness (LVOR) and light (V-LVOR). Response directions were kinematically appropriate to eccentricity in all subjects, but there were significantly more measurable LVOR and V-LVOR responses (63–79%) in younger than older subjects (38–44%, P < 0.01). Minimal LVOR latency averaged 48 ± 4 ms for younger and significantly longer at 70 ± 6 ms for older subjects. In the interval 200–300 ms after surge onset, horizontal LVOR gain (relative to ideal velocity) of younger subjects averaged over all target distances was 0.55 ± 0.04 and was significantly reduced in older subjects to 0.33 ± 0.04. Horizontal V-LVOR gain was 0.58 ± 0.04 in younger and significantly lower at 0.35 ± 0.06 in older subjects. Vertical gains did not differ significantly between groups. Target visibility had no effect in either group during the initial 200 ms. The LVOR and V-LVOR were augmented by saccades in younger more than older subjects. Aging thus decreases LVOR velocity gain, response rate, and saccade augmentation, but prolongs latency. PMID:16551841

Site-specific range uncertainties caused by dose calculation algorithms for proton therapy

NASA Astrophysics Data System (ADS)

Schuemann, J.; Dowdell, S.; Grassberger, C.; Min, C. H.; Paganetti, H.

2014-08-01

The purpose of this study was to assess the possibility of introducing site-specific range margins to replace current generic margins in proton therapy. Further, the goal was to study the potential of reducing margins with current analytical dose calculations methods. For this purpose we investigate the impact of complex patient geometries on the capability of analytical dose calculation algorithms to accurately predict the range of proton fields. Dose distributions predicted by an analytical pencil-beam algorithm were compared with those obtained using Monte Carlo (MC) simulations (TOPAS). A total of 508 passively scattered treatment fields were analyzed for seven disease sites (liver, prostate, breast, medulloblastoma-spine, medulloblastoma-whole brain, lung and head and neck). Voxel-by-voxel comparisons were performed on two-dimensional distal dose surfaces calculated by pencil-beam and MC algorithms to obtain the average range differences and root mean square deviation for each field for the distal position of the 90% dose level (R90) and the 50% dose level (R50). The average dose degradation of the distal falloff region, defined as the distance between the distal position of the 80% and 20% dose levels (R80-R20), was also analyzed. All ranges were calculated in water-equivalent distances. Considering total range uncertainties and uncertainties from dose calculation alone, we were able to deduce site-specific estimations. For liver, prostate and whole brain fields our results demonstrate that a reduction of currently used uncertainty margins is feasible even without introducing MC dose calculations. We recommend range margins of 2.8% + 1.2 mm for liver and prostate treatments and 3.1% + 1.2 mm for whole brain treatments, respectively. On the other hand, current margins seem to be insufficient for some breast, lung and head and neck patients, at least if used generically. If no case specific adjustments are applied, a generic margin of 6.3% + 1.2 mm would be needed for breast, lung and head and neck treatments. We conclude that the currently used generic range uncertainty margins in proton therapy should be redefined site specific and that complex geometries may require a field specific adjustment. Routine verifications of treatment plans using MC simulations are recommended for patients with heterogeneous geometries.

Implementation of a smartphone as a wireless gyroscope application for the quantification of reflex response.

PubMed

LeMoyne, Robert; Mastroianni, Timothy

2014-01-01

The patellar tendon reflex constitutes a fundamental aspect of the conventional neurological evaluation. Dysfunctional characteristics of the reflex response can augment the diagnostic acuity of a clinician for subsequent referral to more advanced medical resources. The capacity to quantify the reflex response while alleviating the growing strain on specialized medical resources is a topic of interest. The quantification of the tendon reflex response has been successfully demonstrated with considerable accuracy and consistency through using a potential energy impact pendulum attached to a reflex hammer for evoking the tendon reflex with a smartphone, such as an iPhone, application representing a wireless accelerometer platform to quantify reflex response. Another sensor integrated into the smartphone, such as an iPhone, is the gyroscope, which measures rate of angular rotation. A smartphone application enables wireless transmission through Internet connectivity of the gyroscope signal recording of the reflex response as an email attachment. The smartphone wireless gyroscope application demonstrates considerable accuracy and consistency for the quantification of the tendon reflex response.

H-reflex modulation in the human medial and lateral gastrocnemii during standing and walking

PubMed Central

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

2011-01-01

Introduction The soleus H-reflex is dynamically modulated during walking. However, modulation of the gastrocnemii H-reflexes has not been studied systematically. Methods The medial and lateral gastrocnemii (MG and LG) and soleus H-reflexes were measured during standing and walking in humans. Results Maximum H-reflex amplitude was significantly smaller in MG (mean 1.1 mV) or LG (1.1 mV) than in soleus (3.3 mV). Despite these size differences, the reflex amplitudes of the three muscles were positively correlated. The MG and LG H-reflexes were phase- and task-dependently modulated in ways similar to the soleus H-reflex. Discussion Although there are anatomical and physiological differences between the soleus and gastrocnemii muscles, the reflexes of the three muscles are similarly modulated during walking and between standing and walking. The findings support the hypothesis that these reflexes are synergistically modulated during walking to facilitate ongoing movement. PMID:22190317

Implementation of an iPhone wireless accelerometer application for the quantification of reflex response.

PubMed

LeMoyne, Robert; Mastroianni, Timothy; Grundfest, Warren; Nishikawa, Kiisa

2013-01-01

The patellar tendon reflex represents an inherent aspect of the standard neurological evaluation. The features of the reflex response provide initial perspective regarding the status of the nervous system. An iPhone wireless accelerometer application integrated with a potential energy impact pendulum attached to a reflex hammer has been successfully developed, tested, and evaluated for quantifying the patellar tendon reflex. The iPhone functions as a wireless accelerometer platform. The wide coverage range of the iPhone enables the quantification of reflex response samples in rural and remote settings. The iPhone has the capacity to transmit the reflex response acceleration waveform by wireless transmission through email. Automated post-processing of the acceleration waveform provides feature extraction of the maximum acceleration of the reflex response ascertained after evoking the patellar tendon reflex. The iPhone wireless accelerometer application demonstrated the utility of the smartphone as a biomedical device, while providing accurate and consistent quantification of the reflex response.

Soleus H-reflex gain in humans walking and running under simulated reduced gravity

NASA Technical Reports Server (NTRS)

Ferris, D. P.; Aagaard, P.; Simonsen, E. B.; Farley, C. T.; Dyhre-Poulsen, P.

2001-01-01

The Hoffmann (H-) reflex is an electrical analogue of the monosynaptic stretch reflex, elicited by bypassing the muscle spindle and directly stimulating the afferent nerve. Studying H-reflex modulation provides insight into how the nervous system centrally modulates stretch reflex responses.A common measure of H-reflex gain is the slope of the relationship between H-reflex amplitude and EMG amplitude. To examine soleus H-reflex gain across a range of EMG levels during human locomotion, we used simulated reduced gravity to reduce muscle activity. We hypothesised that H-reflex gain would be independent of gravity level.We recorded EMG from eight subjects walking (1.25 m s-1) and running (3.0 m s-1) at four gravity levels (1.0, 0.75, 0.5 and 0.25 G (Earth gravity)). We normalised the stimulus M-wave and resulting H-reflex to the maximal M-wave amplitude (Mmax) elicited throughout the stride to correct for movement of stimulus and recording electrodes relative to nerve and muscle fibres. Peak soleus EMG amplitude decreased by 30% for walking and for running over the fourfold change in gravity. As hypothesised, slopes of linear regressions fitted to H-reflex versus EMG data were independent of gravity for walking and running (ANOVA, P > 0.8). The slopes were also independent of gait (P > 0.6), contrary to previous studies. Walking had a greater y-intercept (19.9% Mmax) than running (-2.5% Mmax; P < 0.001). At all levels of EMG, walking H-reflex amplitudes were higher than running H-reflex amplitudes by a constant amount. We conclude that the nervous system adjusts H-reflex threshold but not H-reflex gain between walking and running. These findings provide insight into potential neural mechanisms responsible for spinal modulation of the stretch reflex during human locomotion.

Soleus H-reflex gain in humans walking and running under simulated reduced gravity

PubMed Central

Ferris, Daniel P; Aagaard, Per; Simonsen, Erik B; Farley, Claire T; Dyhre-Poulsen, Poul

2001-01-01

The Hoffmann (H-) reflex is an electrical analogue of the monosynaptic stretch reflex, elicited by bypassing the muscle spindle and directly stimulating the afferent nerve. Studying H-reflex modulation provides insight into how the nervous system centrally modulates stretch reflex responses. A common measure of H-reflex gain is the slope of the relationship between H-reflex amplitude and EMG amplitude. To examine soleus H-reflex gain across a range of EMG levels during human locomotion, we used simulated reduced gravity to reduce muscle activity. We hypothesised that H-reflex gain would be independent of gravity level. We recorded EMG from eight subjects walking (1.25 m s−1) and running (3.0 m s−1) at four gravity levels (1.0, 0.75, 0.5 and 0.25 G (Earth gravity)). We normalised the stimulus M-wave and resulting H-reflex to the maximal M-wave amplitude (Mmax) elicited throughout the stride to correct for movement of stimulus and recording electrodes relative to nerve and muscle fibres. Peak soleus EMG amplitude decreased by ≈30% for walking and for running over the fourfold change in gravity. As hypothesised, slopes of linear regressions fitted to H-reflex versus EMG data were independent of gravity for walking and running (ANOVA, P > 0.8). The slopes were also independent of gait (P > 0.6), contrary to previous studies. Walking had a greater y-intercept (19.9%Mmax) than running (-2.5%Mmax; P < 0.001). At all levels of EMG, walking H-reflex amplitudes were higher than running H-reflex amplitudes by a constant amount. We conclude that the nervous system adjusts H-reflex threshold but not H-reflex gain between walking and running. These findings provide insight into potential neural mechanisms responsible for spinal modulation of the stretch reflex during human locomotion. PMID:11136869

Improvements to Optical Communication Capabilities Achieved through the Optical Injection of Semiconductor Lasers

DTIC Science & Technology

2012-03-22

locked Fabry - Perot laser showed a 57 fold improvement to the bit rate-distance product compared to the free-running case when received optical power...than 10dB for marginal changes in modulation rates. Temperature tuning of the master laser to each of the Fabry - Perot modes of the slave laser...demonstrated over 60 km of SMF in this work, shows that OIL of Fabry - Perot lasers is a viable approach towards a high-speed, long distance capable

Vergence-dependent adaptation of the vestibulo-ocular reflex

NASA Technical Reports Server (NTRS)

Lewis, Richard F.; Clendaniel, Richard A.; Zee, David S.; Shelhamer, M. J. (Principal Investigator)

2003-01-01

The gain of the vestibulo-ocular reflex (VOR) normally depends on the distance between the subject and the visual target, but it remains uncertain whether vergence angle can be linked to changes in VOR gain through a process of context-dependent adaptation. In this study, we examined this question with an adaptation paradigm that modified the normal relationship between vergence angle and retinal image motion. Subjects were rotated sinusoidally while they viewed an optokinetic (OKN) stimulus through either diverging or converging prisms. In three subjects the diverging prisms were worn while the OKN stimulus moved out of phase with the head, and the converging prisms were worn when the OKN stimulus moved in-phase with the head. The relationship between the vergence angle and OKN stimulus was reversed in the fourth subject. After 2 h of training, the VOR gain at the two vergence angles changed significantly in all of the subjects, evidenced by the two different VOR gains that could be immediately accessed by switching between the diverged and converged conditions. The results demonstrate that subjects can learn to use vergence angle as the contextual cue that retrieves adaptive changes in the angular VOR.

Responding to the global economic crisis: inclusive social work practice.

PubMed

Strier, Ron

2013-10-01

The present global economic crisis raises new concerns for social workers. One of its most visible results is the further socioeconomic decline and marginalization of excluded populations. This article suggests that the current circumstances require a much more engaged, egalitarian, and reflexive practice-a practice, based on social rights, that matches the magnitude of the crisis and its negative impact on traditional social work constituencies. Consequently, the article suggests the concept of inclusive social work practice (ISWP), a conceptual framework whose main principles respond to four processes of social exclusion closely related to the present global crisis: extreme social isolation, growing dependency, multiple deprivation, and internalized oppression. The author describes the impact of the global crisis on patterns of social exclusion and presents the methodological foundations of the ISWP framework.

Neurodevelopmental Reflex Testing in Neonatal Rat Pups.

PubMed

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.

Multiple outer-reef tracts along the south Florida bank margin: Outlier reefs, a new windward-margin model

USGS Publications Warehouse

Lidz, Barbara H.; Hine, A.C.; Shinn, Eugene A.; Kindinger, Jack G.

1991-01-01

High-resolution seismic-reflection profiles off the lower Florida Keys reveal a multiple outlier-reef tract system ~0.5 to 1.5 km sea-ward of the bank margin. The system is characterized by a massive, outer main reef tract of high (28 m) unburied relief that parallels the margin and at least two narrower, discontinuous reef tracts of lower relief between the main tract and the shallow bank-margin reefs. The outer tract is ~0.5 to 1 km wide and extends a distance of ~57 km. A single pass divides the outer tract into two main reefs. The outlier reefs developed on antecedent, low-gradient to horizontal offbank surfaces, interpreted to be Pleistocene beaches that formed terracelike features. Radiocarbon dates of a coral core from the outer tract confirm a pre-Holocene age. These multiple outlier reefs represent a new windward-margin model that presents a significant, unique mechanism for progradation of carbonate platforms during periods of sea-level fluctuation. Infilling of the back-reef terrace basins would create new terraced promontories and would extend or "step" the platform seaward for hundreds of metres. Subsequent outlier-reef development would produce laterally accumulating sequences.

Reliability of the Achilles tendon tap reflex evoked during stance using a pendulum hammer.

PubMed

Mildren, Robyn L; Zaback, Martin; Adkin, Allan L; Frank, James S; Bent, Leah R

2016-01-01

The tendon tap reflex (T-reflex) is often evoked in relaxed muscles to assess spinal reflex circuitry. Factors contributing to reflex excitability are modulated to accommodate specific postural demands. Thus, there is a need to be able to assess this reflex in a state where spinal reflex circuitry is engaged in maintaining posture. The aim of this study was to determine whether a pendulum hammer could provide controlled stimuli to the Achilles tendon and evoke reliable muscle responses during normal stance. A second aim was to establish appropriate stimulus parameters for experimental use. Fifteen healthy young adults stood on a forceplate while taps were applied to the Achilles tendon under conditions in which postural sway was constrained (by providing centre of pressure feedback) or unconstrained (no feedback) from an invariant release angle (50°). Twelve participants repeated this testing approximately six months later. Within one experimental session, tap force and T-reflex amplitude were found to be reliable regardless of whether postural sway was constrained (tap force ICC=0.982; T-reflex ICC=0.979) or unconstrained (tap force ICC=0.968; T-reflex ICC=0.964). T-reflex amplitude was also reliable between experimental sessions (constrained ICC=0.894; unconstrained ICC=0.890). When a T-reflex recruitment curve was constructed, optimal mid-range responses were observed using a 50° release angle. These results demonstrate that reliable Achilles T-reflexes can be evoked in standing participants without the need to constrain posture. The pendulum hammer provides a simple method to allow researchers and clinicians to gather information about reflex circuitry in a state where it is involved in postural control. Copyright © 2015 Elsevier B.V. All rights reserved.

Factors Affecting the Occurrence of Spinal Reflexes in Brain Dead Cases.

PubMed

Hosseini, Mahsa Sadat; Ghorbani, Fariba; Ghobadi, Omid; Najafizadeh, Katayoun

2015-08-01

Brain death is defined as the permanent absence of all cortical and brain stem reflexes. A wide range of spontaneous or reflex movements that are considered medullary reflexes are observed in heart beating cases that appear brain dead, which may create uncertainty about the diagnosis of brain death and cause delays in deceased-donor organ donation process. We determined the frequency and type of medullary reflexes and factors affecting their occurrence in brain dead cases. During 1 year, 122 cases who fulfilled the criteria for brain death were admitted to the special intensive care unit for organ procurement of Masih Daneshvari Hospital. Presence of spinal reflexes was evaluated by trained coordinators and was recorded in a form in addition to other information including demographic characteristics, cause of brain death, time from detection of brain death, history of craniotomy, vital signs, serum electrolyte levels, and parameters of arterial blood gas determination. Most cases (63%) included in this study were male, and mean age was 33 ± 15 y. There was > 1 spinal reflex observed in 40 cases (33%). The most frequent reflex was plantar response (17%) following by myoclonus (10%), triple flexion reflex (9%), pronator extension reflex (8%), and undulating toe reflex (7%). Mean systolic blood pressure was significantly higher in cases who exhibited medullary reflexes than other cases (126 ± 19 mm Hg vs 116 ± 17 mm Hg; P = .007). Spinal reflexes occur frequently in brain dead cases, especially when they become hemodynamically stable after treatment in the organ procurement unit. Observing these movements by caregivers and family members has a negative effect on obtaining family consent and organ donation. Increasing awareness about spinal reflexes is necessary to avoid suspicion about the brain death diagnosis and delays in organ donation.

Dissolution of bedded rock salt: A seismic profile across the active eastern margin of the Hutchinson Salt Member, central Kansas

USGS Publications Warehouse

Anderson, N.L.; Hopkins, J.; Martinez, A.; Knapp, R.W.; Macfarlane, P.A.; Watney, W.L.; Black, R.

1994-01-01

Since late Tertiary, bedded rock salt of the Permian Hutchinson Salt Member has been dissolved more-or-less continuously along its active eastern margin in central Kansas as a result of sustained contact with unconfined, undersaturated groundwater. The associated westward migration of the eastern margin has resulted in surface subsidence and the contemporaneous sedimentation of predominantly valley-filling Quarternary alluvium. In places, these alluvium deposits extend more than 25 km to the east of the present-day edge of the main body of contiguous rock salt. The margin could have receded this distance during the past several million years. From an environmental perspective, the continued leaching of the Hutchinson Salt is a major concern. This predominantly natural dissolution occurs in a broad zone across the central part of the State and adversely affects groundwater and surface-water quality as nonpoint source pollution. Significant surface subsidence occurs as well. Most of these subsidence features have formed gradually; others developed in a more catastrophic manner. The latter in particular pose real threats to roadways, railways, and buried oil and gas pipelines. In an effort to further clarify the process of natural salt dissolution in central Kansas and with the long-term goal of mitigating the adverse environmental affects of such leaching, the Kansas Geological Survey acquired a 4-km seismic profile across the eastern margin of the Hutchinson Salt in the Punkin Center area of central Kansas. The interpretation of these seismic data (and supporting surficial and borehole geologic control) is consistent with several hypotheses regarding the process and mechanisms of dissolution. More specifically these data support the theses that: 1. (1) Dissolution along the active eastern margin of the Hutchinson Salt Member was initiated during late Tertiary. Leaching has resulted in the steady westward migration of the eastern margin, surface subsidence, and the contemporaneous deposition of predominantly valley-filling Quarternary alluvium. 2. (2) Along the active eastern margin, the rock salt has been leached vertically from the top down, and horizontally along the uppermost remnant bedded soluble layer(s). As a result, the eastern margin thickens gradually (up to 90 m) and in a stepwise manner from east to west for distances on the order 5-15 km. 3. (3) In places, the Hutchinson Salt Member has been leached locally along NNE-trending paleoshear zones situated to the west of the present-day edge of the main body of contiguous rock salt. Leaching at these sites initiated when the main dissolution front impinged upon preexisting shear zones. ?? 1994.

Along-strike supply of volcanic rifted margins: Implications for plume-influenced rifting and sudden along-strike transitions between volcanic and non-volcanic rifted margins

NASA Astrophysics Data System (ADS)

Ranero, C. R.; Phipps Morgan, J.

2006-12-01

The existence of sudden along-strike transitions between volcanic and non-volcanic rifted margins is an important constraint for conceptual models of rifting and continental breakup. We think there is a promising indirect approach to infer the maximum width of the region of upwelling that exists beneath a rifted margin during the transition from rifting to seafloor-spreading. We infer this width of ~30km from the minimum length of the ridge-offsets that mark the limits of the `region of influence' of on-ridge plumes on the axial relief, axial morphology, and crustal thickness along the ridge and at the terminations of fossil volcanic rifted margins. We adopt Vogt's [1972] hypothesis for along-ridge asthenospheric flow in a narrow vertical slot beneath the axis of plume-influenced `macro-segments' and volcanic rifted margins. We find that: (1) There is a threshold distance to the lateral offsets that bound plume-influenced macrosegments; all such `barrier offsets' are greater than ~30km, while smaller offsets do not appear to be a barrier to along-axis flow. This pattern is seen in the often abrupt transitions between volcanic and non-volcanic rifted margins; these transitions coincide with >30km ridge offsets that mark the boundary between the smooth seafloor morphology and thick crust of a plume- influenced volcanic margin and a neighboring non-volcanic margin, as recorded in 180Ma rifting of the early N. Atlantic, the 42Ma rifting of the Kerguelen-Broken Ridge, and the 66Ma Seychelles-Indian rifting in the Indian Ocean. (2) A similar pattern is seen in the often abrupt transitions between `normal' and plume-influenced mid- ocean ridge segments, which is discussed in a companion presentation by Phipps Morgan and Ranero (this meeting). (3) The coexistance of adjacent volcanic and non-volcanic rifted margin segments is readily explained in this conceptual framework. If the volcanic margin macrosegment is plume-fed by hot asthenosphere along an axial ridge slot, while adjacent non-volcanic margin segments stretch and upwell ambient cooler subcontinental mantle, then there will be a sudden transition from volcanic to non-volcanic margins across a transform offset. (4) A 30km width for the region of ridge upwelling and melting offers a simple conceptual explanation for the apparent 30km threshold length for the existence of strike-slip transform faults and the occurrence of non-transform offsets at smaller ridge offset-distances. (5) The conceptual model leads to the interpretation of the observed characteristic ~1000km-2000km-width of plume-influenced macro- segments as a measure of the maximum potential plume supply into a subaxial slot of 5-10 cubic km per yr. (6) If asthenosphere consumption by plate-spreading is less than plume-supply into a macro-segment, then the shallow seafloor and excess gravitational spreading stresses associated with a plume-influenced ridge can lead to growth of the axial slot by ridge propagation. We think this is a promising conceptual framework with which to understand the differences between volcanic and non-volcanic rifted margins.

Metastasis Infiltration: An Investigation of the Postoperative Brain-Tumor Interface

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

Raore, Bethwel; Schniederjan, Matthew; Prabhu, Roshan

Purpose: This study aims to evaluate brain infiltration of metastatic tumor cells past the main tumor resection margin to assess the biological basis for the use of stereotactic radiosurgery treatment of the tumor resection cavity and visualized resection edge or clinical target volume. Methods and Materials: Resection margin tissue was obtained after gross total resection of a small group of metastatic lesions from a variety of primary sources. The tissue at the border of the tumor and brain tissue was carefully oriented and processed to evaluate the presence of tumor cells within brain tissue and their distance from the resectionmore » margin. Results: Microscopic assessment of the radially oriented tissue samples showed no tumor cells infiltrating the surrounding brain tissue. Among the positive findings were reactive astrocytosis observed on the brain tissue immediately adjacent to the tumor resection bed margin. Conclusions: The lack of evidence of metastatic tumor cell infiltration into surrounding brain suggests the need to target only a narrow depth of the resection cavity margin to minimize normal tissue injury and prevent treatment size-dependent stereotactic radiosurgery complications.« less

The Need for Consensus and Transparency in Assessing Population-Based Rates of Positive Circumferential Radial Margins in Rectal Cancer: Data from Consecutive Cases in a Large Region of Ontario, Canada.

PubMed

Keng, Christine; Coates, Angela; Grubac, Vanja; Lovrics, Peter; DeNardi, Franco; Thabane, Lehana; Simunovic, Marko

2016-02-01

A positive circumferential radial margin (CRM) after rectal cancer surgery is an important predictor of local recurrence. The definition of a positive CRM differs internationally, and reported rates vary greatly in the literature. This study used time-series population-based data to assess positive CRM rates in a region over time and to inform future methods of CRM analysis in a defined geographic area. Chart reviews provided relevant data from consecutive patients undergoing rectal cancer surgery between 2006 and 2012 in all hospitals of the authors' region. Outcomes included rates for pathologic examination of CRM, CRM distance reporting, and positive CRM. The rate of positive CRM was calculated using various definitions. The variations included positive margin cutoffs of CRM at 1 mm or less versus 2 mm or less and inclusion or exclusion of cases without CRM assessment. In this study, 1222 consecutive rectal cancer cases were analyzed. The rate for pathology reporting of CRM distance increased from 54.7 to 93.2 % during the study. Depending on how the rate of positive CRM was defined, its value varied 8.5 to 19.4 % in 2006 and 6.0 to 12.5 % in 2012. Using a pre-specified definition, the rate of positive CRM decreased over time from 14.0 to 6.3 %. A marked increase in CRM distance reporting was observed, whereas the rates of positive CRM dropped, suggesting improved pathologist and surgeon performance over time. Changing definitions greatly influenced the rates of positive CRM, indicating the need for more transparency when such population-based rates are reported in the literature.

Impaction of permanent mandibular second molar: A retrospective study

PubMed Central

Altieri, Federica; Di Mambro, Alfonso; Galluccio, Gabriella; Barbato, Ersilia

2013-01-01

Objective: To determine the prevalence of impacted mandibular second molar (MM2) and the association between MM2 impaction and crowding. The clinical significance of the angle between first and second mandibular molar and of the space between the first mandibular molar (MM1) and the anterior margin of mandibular ramus in MM2 impaction were also evaluated. Material and Methods: In this retrospective study , from the dental records of 2,945 caucasian young orthodontics patients, 40 subjects with MM2 impaction were included in a study group (SG) and compared with a control group (CG) of 200 subjects without MM2 impactions. The crowding, the angle of inclination of MM2, the distance between MM1 and mandibular ramus, the canine and molar relationships, and the lower centre line discrepancy were measured. For the statistical analysis , descriptive statistics and t-Student for independent sample groups were used. Results: The prevalence of impacted MM2 was 1.36%. The independent-Samples t-Test between SG and CG showed: the presence of crowding (P≤0.001), an higher angle values of MM2 inclination (P≤0.001) and a smaller distance between MM1 and the anterior margin of mandibular ramus (P≤0.001) in the SG. Conclusion: The impaction of MM2 is a relatively rare occurrence in orthodontic caucasian populations. The crowding, a higher angle values of MM2 inclination and a reduced distance between MM1 and the anterior margin of mandibular ramus, at the time of one third of MM2 root formation (T1), characterize MM2 impaction. Key words:Impacted mandibular second molar, impaction, orthodontics. PMID:23524438

The differential role of motor cortex in the stretch reflex modulation induced by changes in environmental mechanics and verbal instruction

PubMed Central

Shemmell, Jonathan; An, Je Hi; Perreault, Eric J.

2009-01-01

The motor cortex assumes an increasingly important role in higher mammals relative to that in lower mammals. This is true to such an extent that the human motor cortex is deeply involved in reflex regulation and it is common to speak of “transcortical reflex loops”. Such loops appear to add flexibility to the human stretch reflex, once considered to be immutable, allowing it to adapt across a range of functional tasks. However, the purpose of this adaptation remains unclear. A common proposal is that stretch reflexes contribute to the regulation of limb stability; increased reflex sensitivity during tasks performed in unstable environments supports this hypothesis. Alternatively, prior to movement onset, stretch reflexes can assist an imposed stretch, opposite to what would be expected from a stabilizing response. Here we show that stretch reflex modulation in tasks that require changes in limb stability is mediated by motor cortical pathways, and that these differ from pathways contributing to reflex modulation that depends on how the subject is instructed to react to an imposed perturbation. By timing muscle stretches such that the modulated portion of the reflex occurred within a cortical silent period induced by transcranial magnetic stimulation, we abolished the increase in reflex sensitivity observed when individuals stabilized arm posture within a compliant environment. Conversely, reflex modulation caused by altered task instruction was unaffected by cortical silence. These results demonstrate that task-dependent changes in reflex function can be mediated through multiple neural pathways and that these pathways have task specific roles. PMID:19846713

The differential role of motor cortex in stretch reflex modulation induced by changes in environmental mechanics and verbal instruction.

PubMed

Shemmell, Jonathan; An, Je Hi; Perreault, Eric J

2009-10-21

The motor cortex assumes an increasingly important role in higher mammals relative to that in lower mammals. This is true to such an extent that the human motor cortex is deeply involved in reflex regulation and it is common to speak of "transcortical reflex loops." Such loops appear to add flexibility to the human stretch reflex, once considered to be immutable, allowing it to adapt across a range of functional tasks. However, the purpose of this adaptation remains unclear. A common proposal is that stretch reflexes contribute to the regulation of limb stability; increased reflex sensitivity during tasks performed in unstable environments supports this hypothesis. Alternatively, before movement onset, stretch reflexes can assist an imposed stretch, opposite to what would be expected from a stabilizing response. Here we show that stretch reflex modulation in tasks that require changes in limb stability is mediated by motor cortical pathways, and that these differ from pathways contributing to reflex modulation that depend on how the subject is instructed to react to an imposed perturbation. By timing muscle stretches such that the modulated portion of the reflex occurred within a cortical silent period induced by transcranial magnetic stimulation, we abolished the increase in reflex sensitivity observed when individuals stabilized arm posture within a compliant environment. Conversely, reflex modulation caused by altered task instruction was unaffected by cortical silence. These results demonstrate that task-dependent changes in reflex function can be mediated through multiple neural pathways and that these pathways have task-specific roles.

Persistence of deep-tendon reflexes during partial cataplexy.

PubMed

Barateau, Lucie; Pizza, Fabio; Lopez, Régis; Antelmi, Elena; Plazzi, Giuseppe; Dauvilliers, Yves

2018-05-01

Deep-tendon reflexes are abolished during generalized cataplexy, but whether this is the case in partial cataplexy currently remains unknown. Partial cataplexy may mimic other neurologic/psychiatric phenomena, and knowledge of the reflexes status may provide information for differential diagnosis. We assessed whether deep-tendon reflexes are persistent during partial cataplexy. Five drug-free patients with typical diagnoses of narcolepsy and clear-cut partial cataplexy were diagnosed in Reference Narcolepsy Centers in France and Italy. Biceps and patellar reflexes were elicited by physicians in charge and video-documented during cataplexy. Reflexes were assessed several times for each patient in different conditions and for various localizations of cataplexy. The absence of tendon reflexes and complete loss of muscle tone during generalized cataplexy was confirmed, but the persistence of those reflexes during several partial cataplectic attacks at different ages, gender, localization of cataplexy (upper limbs, face) and reflexes (biceps, patellar) in drug-naive or withdrawal conditions was documented. The persistence of tendon reflexes during several partial cataplexy episodes contrasts with their absence during generalized cataplexy. This discovery has clinical implications: the persistence of tendon reflexes does not rule out cataplexy diagnosis for partial attacks, whereas their transient abolishment or persistence during generalized attacks indicates cataplexy or pseudocataplexy, respectively. Copyright © 2018. Published by Elsevier B.V.

Quantitative measurement of marginal disintegration of ceramic inlays.

PubMed

Hayashi, Mikako; Tsubakimoto, Yuko; Takeshige, Fumio; Ebisu, Shigeyuki

2004-01-01

The objectives of this study include establishing a method for quantitative measurement of marginal change in ceramic inlays and clarifying their marginal disintegration in vivo. An accurate CCD optical laser scanner system was used for morphological measurement of the marginal change of ceramic inlays. The accuracy of the CCD measurement was assessed by comparing it with microscopic measurement. Replicas of 15 premolars restored with Class II ceramic inlays at the time of placement and eight years after restoration were used for morphological measurement by means of the CCD laser scanner system. Occlusal surfaces of the restored teeth were scanned and cross-sections of marginal areas were computed with software. Marginal change was defined as the area enclosed by two profiles obtained by superimposing two cross-sections of the same location at two different times and expressing the maximum depth and mean area of the area enclosed. The accuracy of this method of measurement was 4.3 +/- 3.2 microm in distance and 2.0 +/- 0.6% in area. Quantitative marginal changes for the eight-year period were 10 x 10 microm in depth and 50 x 10(3) microm2 in area at the functional cusp area and 7 x 10 microm in depth and 28 x 10(3) microm2 in area at the non-functional cusp area. Marginal disintegration at the functional cusp area was significantly greater than at the non-functional cusp area (Wilcoxon signed-ranks test, p < 0.05). This study constitutes a quantitative measurement of in vivo deterioration in marginal adaptation of ceramic inlays and indicates that occlusal force may accelerate marginal disintegration.

Primitive Reflexes and Attention-Deficit/Hyperactivity Disorder: Developmental Origins of Classroom Dysfunction

ERIC Educational Resources Information Center

Taylor, Myra; Houghton, Stephen; Chapman, Elaine

2004-01-01

The present research studied the symptomatologic overlap of AD/HD behaviours and retention of four primitive reflexes (Moro, Tonic Labyrinthine Reflex [TLR], Asymmetrical Tonic Neck Reflex [ATNR], Symmetrical Tonic Neck Reflex [STNR]) in 109 boys aged 7-10 years. Of these, 54 were diagnosed with AD/HD, 34 manifested sub-syndromal coordination,…

Development of the Stretch Reflex in the Newborn: Reciprocal Excitation and Reflex Irradiation.

ERIC Educational Resources Information Center

Myklebust, Barbara M.; Gottlieb, Gerald L.

1993-01-01

When tendon jerk reflexes were tested in seven newborns from one- to three-days old, stretch reflex responses in all major muscle groups of the lower limb were elicited. This "irradiation of reflexes" is a normal phenomenon in newborns, with the pathway becoming suppressed during normal maturation. In individuals with cerebral palsy,…

Neogene rotations and quasicontinuous deformation of the Pacific Northwest continental margin

USGS Publications Warehouse

England, Philip; Wells, Ray E.

1991-01-01

Paleomagnetically determined rotations about vertical axes of 15 to 12 Ma flows of the Miocene Columbia River Basalt Group of Oregon and Washington decrease smoothly with distance from the plate margin, consistent with a simple physical model for continental deformation that assumes the lithosphere behaves as a thin layer of fluid. The average rate of northward translation of the continental margin since 15 Ma calculated from the rotations, using this model, is about 15 mm/yr, which suggests that much of the tangential motion between the Juan de Fuca and North American plates since middle Miocene time has been taken up by deformation of North America. The fluid-like character of the large-scale deformation implies that the brittle upper crust follows the motions of the deeper parts of the lithosphere.

Simulated effects of host fish distribution on juvenile unionid mussel dispersal in a large river

USGS Publications Warehouse

Daraio, J.A.; Weber, L.J.; Zigler, S.J.; Newton, T.J.; Nestler, J.M.

2012-01-01

Larval mussels (Family Unionidae) are obligate parasites on fish, and after excystment from their host, as juveniles, they are transported with flow. We know relatively little about the mechanisms that affect dispersal and subsequent settlement of juvenile mussels in large rivers. We used a three-dimensional hydrodynamic model of a reach of the Upper Mississippi River with stochastic Lagrangian particle tracking to simulate juvenile dispersal. Sensitivity analyses were used to determine the importance of excystment location in two-dimensional space (lateral and longitudinal) and to assess the effects of vertical location (depth in the water column) on dispersal distances and juvenile settling distributions. In our simulations, greater than 50% of juveniles mussels settled on the river bottom within 500 m of their point of excystment, regardless of the vertical location of the fish in the water column. Dispersal distances were most variable in environments with higher velocity and high gradients in velocity, such as along channel margins, near the channel bed, or where effects of river bed morphology caused large changes in hydraulics. Dispersal distance was greater and variance was greater when juvenile excystment occurred in areas where vertical velocity (w) was positive (indicating an upward velocity) than when w was negative. Juvenile dispersal distance is likely to be more variable for mussels species whose hosts inhabit areas with steeper velocity gradients (e.g. channel margins) than a host that generally inhabits low-flow environments (e.g. impounded areas).

Supraspinal control of spinal reflex responses to body bending during different behaviours in lampreys

PubMed Central

Hsu, Li‐Ju; Zelenin, Pavel V.; Orlovsky, Grigori N.

2016-01-01

Key points Spinal reflexes are substantial components of the motor control system in all vertebrates and centrally driven reflex modifications are essential to many behaviours, but little is known about the neuronal mechanisms underlying these modifications.To study this issue, we took advantage of an in vitro brainstem–spinal cord preparation of the lamprey (a lower vertebrate), in which spinal reflex responses to spinal cord bending (caused by signals from spinal stretch receptor neurons) can be evoked during different types of fictive behaviour.Our results demonstrate that reflexes observed during fast forward swimming are reversed during escape behaviours, with the reflex reversal presumably caused by supraspinal commands transmitted by a population of reticulospinal neurons.NMDA receptors are involved in the formation of these commands, which are addressed primarily to the ipsilateral spinal networks.In the present study the neuronal mechanisms underlying reflex reversal have been characterized for the first time. Abstract Spinal reflexes can be modified during different motor behaviours. However, our knowledge about the neuronal mechanisms underlying these modifications in vertebrates is scarce. In the lamprey, a lower vertebrate, body bending causes activation of intraspinal stretch receptor neurons (SRNs) resulting in spinal reflexes: activation of motoneurons (MNs) with bending towards either the contralateral or ipsilateral side (a convex or concave response, respectively). The present study had two main aims: (i) to investigate how these spinal reflexes are modified during different motor behaviours, and (ii) to reveal reticulospinal neurons (RSNs) transmitting commands for the reflex modification. For this purpose in in vitro brainstem–spinal cord preparation, RSNs and reflex responses to bending were recorded during different fictive behaviours evoked by supraspinal commands. We found that during fast forward swimming MNs exhibited convex responses. By contrast, during escape behaviours, MNs exhibited concave responses. We found RSNs that were activated during both stimulation causing reflex reversal without initiation of any specific behaviour, and stimulation causing reflex reversal during escape behaviour. We suggest that these RSNs transmit commands for the reflex modification. Application of the NMDA antagonist (AP‐5) to the brainstem significantly decreased the reversed reflex, suggesting involvement of NMDA receptors in the formation of these commands. Longitudinal split of the spinal cord did not abolish the reflex reversal caused by supraspinal commands, suggesting an important role for ipsilateral networks in determining this type of motor response. This is the first study to reveal the neuronal mechanisms underlying supraspinal control of reflex reversal. PMID:27589479

Protective role of aerodigestive reflexes against aspiration: study on subjects with impaired and preserved reflexes.

PubMed

Dua, Kulwinder; Surapaneni, Sri Naveen; Kuribayashi, Shiko; Hafeezullah, Mohammed; Shaker, Reza

2011-06-01

Direct evidence to support the airway protective function of aerodigestive reflexes triggered by pharyngeal stimulation was previously demonstrated by abolishing these reflexes by topical pharyngeal anesthesia in normal subjects. Studies have also shown that these reflexes deteriorate in cigarette smokers. Aim of this study was to determine the influence of defective pharyngeal aerodigestive reflexes on airway protection in cigarette smokers. Pharyngoglottal Closure reflex; PGCR, Pharyngo-UES Contractile reflex; PUCR, and Reflexive Pharyngeal Swallow; RPS were studied in 15 healthy non-smokers (24.2±3.3 SD y, 7 males) and 15 healthy chronic smokers (27.3±8.1, 7 males). To elicit these reflexes and to evaluate aspiration, colored water was perfused into the hypopharynx at the rate of 1 mL/min. Maximum volume of water that can safely dwell in the hypopharynx before spilling into the larynx (Hypopharyngeal Safe Volume; HPSV) and the threshold volume to elicit PGCR, PUCR, and RPS were determined in smokers and results compared with non-smokers. At baseline, RPS was elicited in all non-smokers (100%) and in only 3 of 15 smokers (20%; P<.001). None of the non-smokers showed evidence of laryngeal spillage of water, whereas 12 of 15 smokers with absent RPS had laryngeal spillage. Pharyngeal anesthesia abolished RPS reflex in all non-smokers resulting in laryngeal spillage. The HPSV was 0.61±0.06 mL and 0.76±0.06 mL in non-smokers and smokers respectively (P=.1). Deteriorated reflexive pharyngeal swallow in chronic cigarette smokers predispose them to risks of aspiration and similarly, abolishing this reflex in non-smokers also results in laryngeal spillage. These observations directly demonstrate the airway protective function of RPS. Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.

Submandibular approach to the C2-3 disc level: microsurgical anatomy with clinical application.

PubMed

Russo, Antonino; Albanese, Erminia; Quiroga, Monica; Ulm, Arthur J

2009-04-01

Approaching the C2-3 disc level is challenging because of its location behind the mandible and the vital neurovascular structures overlying the area. The purpose of this study was to illustrate in a stepwise fashion the microsurgical anatomy of the submandibular approach to the C2-3 disc. Ten adult formalin-fixed cadaveric specimens (20 sides) were studied. Particular attention was paid to the structures limiting the exposure. The authors measured the distance between the inferior border of the mandible and the marginal mandibular branch of the facial nerve running inferior to the mandible, the distance between the horizontal segment of the hypoglossal nerve and the hyoid bone, and the distance between the horizontal segment of the hypoglossal nerve and the mandible. They compared the location of the superior laryngeal nerve with regard to the submandibular and the standard Smith-Robinson approaches. A clinical case illustrating the usefulness of the surgical technique in this region is presented. The mean distance between the inferior border of the mandible and the lowest point of the marginal mandibular branch of the facial nerve was 6.7 +/- 1.69 mm. The hypoglossal nerve's mean distance above the hyoid bone was 8.4 +/- 1.78 mm and below the mandible was 19.6 +/- 6.39 mm. The internal branch of the superior laryngeal nerve, with respect to the cervical spine, always entered the thyrohyoid membrane just inferior to the C-3 vertebral body. The superior laryngeal nerve was found to be an impediment to approaching the C2-3 disc through the standard Smith-Robinson approach. The submandibular approach provides excellent exposure, with a perpendicular view of the C2-3 disc level. This approach is one of the options to be considered when dealing with high cervical pathologies.

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

Gavioli, Margherita; Losi, Lorena; Luppi, Gabriele

Purpose: To assess the frequency and magnitude of changes in lower rectal cancer resulting from preoperative therapy and its impact on sphincter-saving surgery. Preoperative therapy can increase the rate of preserving surgery by shrinking the tumor and enhancing its distance from the anal sphincter. However, reliable data concerning these modifications are not yet available in published reports. Methods and Materials: A total of 98 cases of locally advanced cancer of the lower rectum (90 Stage uT3-T4N0-N+ and 8 uT2N+M0) that had undergone preoperative therapy were studied by endorectal ultrasonography. The maximal size of the tumor and its distance from themore » anal sphincter were measured in millimeters before and after preoperative therapy. Surgery was performed 6-8 weeks after therapy, and the histopathologic margins were compared with the endorectal ultrasound data. Results: Of the 90 cases, 82.5% showed tumor downsizing, varying from one-third to two-thirds or more of the original tumor mass. The distance between the tumor and the anal sphincter increased in 60.2% of cases. The median increase was 0.73 cm (range, 0.2-2.5). Downsizing was not always associated with an increase in distance. Preserving surgery was performed in 60.6% of cases. It was possible in nearly 30% of patients in whom the cancer had reached the anal sphincter before the preoperative therapy. The distal margin was tumor free in these cases. Conclusion: The results of our study have shown that in very low rectal cancer, preoperative therapy causes tumor downsizing in >80% of cases and in more than one-half enhances the distance between the tumor and anal sphincter. These modifications affect the primary surgical options, facilitating or making sphincter-saving surgery possible.« less

Reversible grasp reflexes in normal pressure hydrocephalus.

PubMed

Thomas, Rhys H; Bennetto, Luke; Silva, Mark T

2009-05-01

We present two cases of normal pressure hydrocephalus in combination with grasp reflexes. In both cases the grasp reflexes disappeared following high volume cerebrospinal fluid removal. In one of the cases the grasp reflexes returned over a period of weeks but again resolved following definitive cerebrospinal fluid shunting surgery, and remained absent until final follow up at 9 months. We hypothesise that resolving grasp reflexes following high volume CSF removal has both diagnostic and prognostic value in normal pressure hydrocephalus, encouraging larger studies on the relevance of primitive reflexes in NPH.

Morphometric analysis of infraorbital foramen in Indian dry skulls

PubMed Central

2011-01-01

We analyzed the variability in position, shape, size and incidence of the infraorbital foramen in Indian dry skulls as little literature is available on this foramen in Indians to prevent clinical complications during maxillofacial surgery and regional block anesthesia. Fifty-five Indian skulls from the Department of Anatomy CSM Medical University were examined. The 110 sides (left and right) of the skulls were analyzed by measuring the infraorbital foramina distances from infraorbital margin and the piriform aperture on both sides. The vertical and horizontal dimensions were also measured. All measurements were taken with a compass transferred to calipers and analyzed statistically. The mean distances between the infraorbital foramen and the infraorbital margin on the right and left side were 6.12 mm and 6.19 mm, respectively. The mean distances between the infraorbital foramen and the piriform aperture were 15.31 mm and 15.80 mm on the right and left sides, respectively. The mean vertical dimensions on the right and left side were 3.39 mm and 3.75 mm, respectively. The mean horizontal dimensions on the two sides were 3.19 mm and 3.52 mm. These results provide detailed knowledge of the anatomical characteristics and clinical importance of the infraorbital foramina which are of paramount importance for surgeons when performing maxillofacial surgery and regional block anesthesia. PMID:21519552

Simultaneous measurement of noise-activated middle-ear muscle reflex and stimulus frequency otoacoustic emissions.

PubMed

Goodman, Shawn S; Keefe, Douglas H

2006-06-01

Otoacoustic emissions serve as a noninvasive probe of the medial olivocochlear (MOC) reflex. Stimulus frequency otoacoustic emissions (SFOAEs) elicited by a low-level probe tone may be the optimal type of emission for studying MOC effects because at low levels, the probe itself does not elicit the MOC reflex [Guinan et al. (2003) J. Assoc. Res. Otolaryngol. 4:521]. Based on anatomical considerations, the MOC reflex activated by ipsilateral acoustic stimulation (mediated by the crossed olivocochlear bundle) is predicted to be stronger than the reflex to contralateral stimulation. Broadband noise is an effective activator of the MOC reflex; however, it is also an effective activator of the middle-ear muscle (MEM) reflex, which can make results difficult to interpret. The MEM reflex may be activated at lower levels than measured clinically, and most previous human studies have not explicitly included measurements to rule out MEM reflex contamination. The current study addressed these issues using a higher-frequency SFOAE probe tone to test for cochlear changes mediated by the MOC reflex, while simultaneously monitoring the MEM reflex using a low-frequency probe tone. Broadband notched noise was presented ipsilaterally at various levels to elicit probe-tone shifts. Measurements are reported for 15 normal-hearing subjects. With the higher-frequency probe near 1.5 kHz, only 20% of subjects showed shifts consistent with an MOC reflex in the absence of an MEM-induced shift. With the higher-frequency probe near 3.5 kHz, up to 40% of subjects showed shifts in the absence of an MEM-induced shift. However, these responses had longer time courses than expected for MOC-induced shifts, and may have been dominated by other cochlear processes, rather than MOC reflex. These results suggest caution in the interpretation of effects observed using ipsilaterally presented acoustic activators intended to excite the MOC reflex.

Retention of primitive reflexes and delayed motor development in very low birth weight infants.

PubMed

Marquis, P J; Ruiz, N A; Lundy, M S; Dillard, R G

1984-06-01

Primitive reflexes and motor development were evaluated in 127 very low birth weight (VLBW) infants (birth weight less than 1501 grams) at four months corrected age. The asymmetrical tonic neck reflex, tonic labyrinth reflex, and Moro reflex were assessed for each child. The ability of each child to reach (obtain a red ring) and roll were observed. The child's performance on the gross motor scale of the Denver Development Screening Test was recorded. Thirty-seven term infants were administered identical evaluations at four months of age. The VLBW infants retained stronger primitive reflexes and exhibited a significantly higher incidence of motor delays than term infants. Significant correlations existed between the strength of the primitive reflexes and early motor development for VLBW infants. This study confirms a high incidence of motor delays among VLBW infants and demonstrates a clear association between retained primitive reflexes and delayed motor development in VLBW infants.

Opal-CT in chert beneath the toe of the Tohoku margin and its influence on the seismic aseismic transition in subduction zones

NASA Astrophysics Data System (ADS)

Kameda, Jun; Okamoto, Atsushi; Sato, Kiminori; Fujimoto, Koichiro; Yamaguchi, Asuka; Kimura, Gaku

2017-01-01

Thick accumulation of chert is a ubiquitous feature of old oceanic plates at convergent margins. In this study, we investigate chert fragments recovered by the Integrated Ocean Drilling Program expedition 343 at the Japan Trench where the 2011 Tohoku-Oki earthquake (Mw 9.0) occurred. This sample provides a unique opportunity to investigate in situ chert diagenesis at an active subduction margin and its influence on the kinematics of megathrust faulting. Our mineralogical analyses revealed that the chert is characterized by hydrous opal-CT and may therefore be highly deformable via pressure solution creep and readily accommodate shear strain between the converging plates at driving stresses of kilopascal order. As chert diagenesis advances, any further deformation requires stresses of >100 MPa, given the increasing transport distances for solutes as represented in cherts on land. The chert diagenesis is thus related to the mechanical transition from a weakly to strongly coupled plate interface at this margin.

Assessment of tsunami hazard to the U.S. East Coast using relationships between submarine landslides and earthquakes

USGS Publications Warehouse

ten Brink, Uri S.; Lee, H.J.; Geist, E.L.; Twichell, D.

2009-01-01

Submarine landslides along the continental slope of the U.S. Atlantic margin are potential sources for tsunamis along the U.S. East coast. The magnitude of potential tsunamis depends on the volume and location of the landslides, and tsunami frequency depends on their recurrence interval. However, the size and recurrence interval of submarine landslides along the U.S. Atlantic margin is poorly known. Well-studied landslide-generated tsunamis in other parts of the world have been shown to be associated with earthquakes. Because the size distribution and recurrence interval of earthquakes is generally better known than those for submarine landslides, we propose here to estimate the size and recurrence interval of submarine landslides from the size and recurrence interval of earthquakes in the near vicinity of the said landslides. To do so, we calculate maximum expected landslide size for a given earthquake magnitude, use recurrence interval of earthquakes to estimate recurrence interval of landslide, and assume a threshold landslide size that can generate a destructive tsunami. The maximum expected landslide size for a given earthquake magnitude is calculated in 3 ways: by slope stability analysis for catastrophic slope failure on the Atlantic continental margin, by using land-based compilation of maximum observed distance from earthquake to liquefaction, and by using land-based compilation of maximum observed area of earthquake-induced landslides. We find that the calculated distances and failure areas from the slope stability analysis is similar or slightly smaller than the maximum triggering distances and failure areas in subaerial observations. The results from all three methods compare well with the slope failure observations of the Mw = 7.2, 1929 Grand Banks earthquake, the only historical tsunamigenic earthquake along the North American Atlantic margin. The results further suggest that a Mw = 7.5 earthquake (the largest expected earthquake in the eastern U.S.) must be located offshore and within 100??km of the continental slope to induce a catastrophic slope failure. Thus, a repeat of the 1755 Cape Anne and 1881 Charleston earthquakes are not expected to cause landslides on the continental slope. The observed rate of seismicity offshore the U.S. Atlantic coast is very low with the exception of New England, where some microseismicity is observed. An extrapolation of annual strain rates from the Canadian Atlantic continental margin suggests that the New England margin may experience the equivalent of a magnitude 7 earthquake on average every 600-3000??yr. A minimum triggering earthquake magnitude of 5.5 is suggested for a sufficiently large submarine failure to generate a devastating tsunami and only if the epicenter is located within the continental slope.

Interlimb Reflexes Induced by Electrical Stimulation of Cutaneous Nerves after Spinal Cord Injury

PubMed Central

Butler, Jane E.; Godfrey, Sharlene; Thomas, Christine K.

2016-01-01

Whether interlimb reflexes emerge only after a severe insult to the human spinal cord is controversial. Here the aim was to examine interlimb reflexes at rest in participants with chronic (>1 year) spinal cord injury (SCI, n = 17) and able-bodied control participants (n = 5). Cutaneous reflexes were evoked by delivering up to 30 trains of stimuli to either the superficial peroneal nerve on the dorsum of the foot or the radial nerve at the wrist (5 pulses, 300 Hz, approximately every 30 s). Participants were instructed to relax the test muscles prior to the delivery of the stimuli. Electromyographic activity was recorded bilaterally in proximal and distal arm and leg muscles. Superficial peroneal nerve stimulation evoked interlimb reflexes in ipsilateral and contralateral arm and contralateral leg muscles of SCI and control participants. Radial nerve stimulation evoked interlimb reflexes in the ipsilateral leg and contralateral arm muscles of control and SCI participants but only contralateral leg muscles of control participants. Interlimb reflexes evoked by superficial peroneal nerve stimulation were longer in latency and duration, and larger in magnitude in SCI participants. Interlimb reflex properties were similar for both SCI and control groups for radial nerve stimulation. Ascending interlimb reflexes tended to occur with a higher incidence in participants with SCI, while descending interlimb reflexes occurred with a higher incidence in able-bodied participants. However, the overall incidence of interlimb reflexes in SCI and neurologically intact participants was similar which suggests that the neural circuitry underlying these reflexes does not necessarily develop after central nervous system injury. PMID:27049521

The Dynamics of the Stapedial Acoustic Reflex.

NASA Astrophysics Data System (ADS)

Moss, Sherrin Mary

Available from UMI in association with The British Library. This thesis aims to separate the neural and muscular components of the stapedial acoustic reflex, both anatomically and physiologically. It aims to present an hypothesis to account for the differences between ipsilateral and contralateral reflex characteristics which have so far been unexplained, and achieve a greater understanding of the mechanisms underlying the reflex dynamics. A technique enabling faithful reproduction of the time course of the reflex is used throughout the experimental work. The technique measures tympanic membrane displacement as a result of reflex stapedius muscle contraction. The recorded response can be directly related to the mechanics of the middle ear and stapedius muscle contraction. Some development of the technique is undertaken by the author. A model of the reflex neural arc and stapedius muscle dynamics is evolved that is based upon a second order system. The model is unique in that it includes a latency in the ipsilateral negative feedback loop. Oscillations commonly observed on reflex responses are seen to be produced because of the inclusion of a latency in the feedback loop. The model demonstrates and explains the complex relationships between neural and muscle dynamic parameters observed in the experimental work. This more comprehensive understanding of the interaction between the stapedius dynamics and the neural arc of the reflex would not usually have been possible using human subjects, coupled with a non-invasive measurement technique. Evidence from the experimental work revealed the ipsilateral reflex to have, on average, a 5 dB lower threshold than the contralateral reflex. The oscillatory charcteristics, and the steady state response, of the contralateral reflex are also seen to be significantly different from those of the ipsilateral reflex. An hypothesis to account for the experimental observations is proposed. It is propounded that chemical neurotransmitters, and their effect upon the contralateral reflex arc from the site of the superior olivary complex to the motoneurones innervating the stapedius, account for the difference between the contralateral and ipsilateral reflex thresholds and dynamic characteristics. In the past two years the measurement technique used for the experimental work has developed from an audiological to a neurological diagnostic tool. This has enabled the results from the study to be applied in the field for valuable biomechanical and neurological explanations of the reflex response. (Abstract shortened by UMI.).

Sensory feedback from the urethra evokes state-dependent lower urinary tract reflexes in rat.

PubMed

Danziger, Zachary C; Grill, Warren M

2017-08-15

The lower urinary tract is regulated by reflexes responsible for maintaining continence and producing efficient voiding. It is unclear how sensory information from the bladder and urethra engages differential, state-dependent reflexes to either maintain continence or promote voiding. Using a new in vivo experimental approach, we quantified how sensory information from the bladder and urethra are integrated to switch reflex responses to urethral sensory feedback from maintaining continence to producing voiding. The results demonstrate how sensory information regulates state-dependent reflexes in the lower urinary tract and contribute to our understanding of the pathophysiology of urinary retention and incontinence where sensory feedback may engage these reflexes inappropriately. Lower urinary tract reflexes are mediated by peripheral afferents from the bladder (primarily in the pelvic nerve) and the urethra (in the pudendal and pelvic nerves) to maintain continence or initiate micturition. If fluid enters the urethra at low bladder volumes, reflexes relax the bladder and evoke external urethral sphincter (EUS) contraction (guarding reflex) to maintain continence. Conversely, urethral flow at high bladder volumes, excites the bladder (micturition reflex) and relaxes the EUS (augmenting reflex). We conducted measurements in a urethane-anaesthetized in vivo rat preparation to characterize systematically the reflexes evoked by fluid flow through the urethra. We used a novel preparation to manipulate sensory feedback from the bladder and urethra independently by controlling bladder volume and urethral flow. We found a distinct bladder volume threshold (74% of bladder capacity) above which flow-evoked bladder contractions were 252% larger and evoked phasic EUS activation 2.6 times as often as responses below threshold, clearly demonstrating a discrete transition between continence (guarding) and micturition (augmenting) reflexes. Below this threshold urethral flow evoked tonic EUS activity, indicative of the guarding reflex, that was proportional to the urethral flow rate. These results demonstrate the complementary roles of sensory feedback from the bladder and urethra in regulating reflexes in the lower urinary tract that depend on the state of the bladder. Understanding the neural control of functional reflexes and how they are mediated by sensory information in the bladder and urethra will open new opportunities, especially in neuromodulation, to treat pathologies of the lower urinary tract. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Adopting Disruptive Technologies in Traditional Universities: Continuing Education as an Incubator for Innovation.

ERIC Educational Resources Information Center

Archer, Walter; Anderson, Terry; Garrison, Randy

1999-01-01

Traditional universities are feeling the impact of "disruptive technologies" such as distance education. Seeing how businesses have responded to such disruptions, universities should "incubate" innovations in a semiautonomous unit such as continuing education, which can address new markets with low margins. (SK)

Patterns of Intraosseous Recurrence After Stereotactic Body Radiation Therapy for Coxal Bone Metastasis.

PubMed

Ito, Kei; Shimizuguchi, Takuya; Nihei, Keiji; Furuya, Tomohisa; Ogawa, Hiroaki; Tanaka, Hiroshi; Sasai, Keisuke; Karasawa, Katsuyuki

2018-01-01

To analyze the detailed pattern of intraosseous failure after stereotactic body radiation therapy (SBRT) for coxal bone metastasis. Patients treated with SBRT to coxal bone metastasis were identified by retrospective chart review. The SBRT doses were 30 Gy or 35 Gy in 5 fractions. A margin of 5 to 10 mm was added to the gross tumor volume to create the clinical target volume. We evaluated the presence or absence of intraosseous recurrence using magnetic resonance imaging. Intraosseous recurrences were assessed as "in-field" or "marginal/out-of-field." In addition, we measured the distance between the center of the recurrent tumor and the nearest edge of the initial bone metastasis in cases of marginal/out-of-field recurrence. Seventeen patients treated for 17 coxal bone metastases were included. Median age was 64 years (range, 48-79 years). Coxal lesions involved the ilium in 14 cases, pubis in 3, and ischium in 4 (3 lesions crossed over multiple regions). Patients most commonly had renal cell carcinoma (29.4%), followed by lung, hepatic cell, and colorectal cancers (23.5%, 11.8%, and 11.8%, respectively). Median follow-up after SBRT was 13 months (range, 2-44 months). Among all 17 cases, 7 cases developed 8 intraosseous recurrences, including in-field recurrence in 1 case and marginal/out-of-field recurrences in 7 cases. Median time to intraosseous recurrence was 10 months (range, 2-35 months). Among 7 cases with marginal/out-of-field recurrence, mean distance to the center of the recurrent tumor from the nearest edge of the initial bone metastasis was 34 mm (range, 15-55 mm). Most recurrences were observed out-of-field in the same coxal bone. These results suggest that defining the optimal clinical target volume in SBRT for coxal bone metastasis to obtain sufficient local tumor control is difficult. Copyright © 2017 Elsevier Inc. All rights reserved.

Abnormal flexor carpi radialis H-reflex as a specific indicator of C7 as compared with C6 radiculopathy.

PubMed

Zheng, Chaojun; Zhu, Yu; Lv, Feizhou; Ma, Xiaosheng; Xia, Xinlei; Wang, Lixun; Jin, Xiang; Weber, Robert; Jiang, Jianyuan; Anuvat, Kevin

2014-12-01

The H-reflex of the flexor carpi radialis (FCR H-reflex) has not been commonly used for the diagnosis of cervical radiculopathy when compared with the routinely tested soleus H-reflex. Although both S1 and S2 roots innervate the soleus, the H-reflex is selectively related to S1 nerve root function clinically. Flexor carpi radialis is also innervated by two nerve roots which are C6 and C7. Although they are among the most common roots involved in cervical radiculopathy, few studies reported if the attenuation of the FCR H-reflex is caused by lesions affecting C7 or C6 nerve roots, or both. We aimed to identify whether an abnormal FCR H-reflex was attributed to the C7 or C6 nerve root lesion, or both. The sensitivities of needle electromyography, FCR H-reflex, and provocative tests in unilateral C7 or C6 radiculopathy were also compared in this study. A concentric needle electrode recorded bilateral FCR H-reflexes in 41 normal subjects (control group), 51 patients with C7 radiculopathy, and 54 patients with C6 radiculopathy. Clinical, radiological, and surgical approaches identified the precise single cervical nerve root involved in all patient groups. The H-reflex and M-wave latencies were measured and compared bilaterally. Abnormal FCR H-reflex was defined as the absence of the H-reflex or a side-to-side difference over 1.5 milliseconds which was based on the normal side-to-side difference of the H-reflex latency of 16.9 milliseconds (SD = 1.7 milliseconds) from the control group. We also determined standard median and ulnar conduction and needle electromyography. The provocative tests included bilateral determination of the Shoulder Abduction and Spurling's tests in all radiculopathy group patients. Abnormal FCR H-reflexes were recorded in 45 (88.2%) of C7 radiculopathy group patients, and 2 (3.7%) of C6 radiculopathy group patients (P < 0.05). Needle electromyography was abnormal in 41 (80.4%) of C7 radiculopathy patients and 43 (79.6%) of C6 radiculopathy patients. Provocative tests were positive in 15 (29.4%) of C7 radiculopathy patients and 25 (46.3%) of C6 radiculopathy patients. Flexor carpi radialis H-Reflex provides a sensitive assessment of evaluating the C7 spinal reflex pathway. Clinically, a combination of the FCR H-reflex with needle electromyography may yield the highest level of diagnostic information for evaluating clinical cases of C7 radiculopathy.

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

PubMed

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.

The Reflexes of the Fundus Oculi

PubMed Central

Ballantyne, A. J.

1940-01-01

The fundus reflexes reveal, in a manner not yet completely understood, the texture and contour of the reflecting surfaces and the condition of the underlying tissues. In this way they may play an important part in the biomicroscopy of the eye. The physiological reflexes are seen at their best in the eyes of young subjects, in well-pigmented eyes, with undilated pupils and with emmetropic refraction. Their absence during the first two decades, or their presence after the forties, their occurrence in one eye only, their appearance, disappearance or change of character should suggest the possibility of some pathological state. The investigation and interpretation of the reflexes are notably assisted by comparing the appearances seen with long and short wave lights such as those of the sodium and mercury vapour lamps, in addition to the usual ophthalmoscopic lights. Most of the surface reflexes disappear in the light of the sodium lamp, sometimes revealing important changes in the deeper layers of the retina and choroid. The physiological reflexes, chiefly formed on the surface of the internal limiting membrane, take the forms of the familiar watered silk or patchy reflexes, the peri-macular halo, the fan reflex in the macular depression and the reflex from the foveal pit. The watered silk or patchy reflexes often show a delicate striation which follows the pattern of the nerve-fibre layer, or there may be a granular or criss-cross texture. Reflexes which entirely lack these indications of “texture” should be considered as possibly pathological. This applies to the “beaten metal” reflexes and to those formed on the so-called hyaloid membrane. The occurrence of physiological reflexes in linear form is doubtful, and the only admittedly physiological punctate reflexes are the so-called Gunn's dots. Surface reflexes which are broken up into small points or flakes are pathological, and are most frequently seen in the central area of the fundus in cases of pigmentary degeneration of the retina or after the subsidence of severe retinitis or retino-choroiditis. A mirror reflex from the layer of pigmented epithelium or from the external limiting membrane is sometimes recognizable in normal eyes, especially in the brunette fundus. In such, it forms the background to a striking picture of the fine circumfoveal vessels. Pathological reflexes from the level of the pigmented epithelium or of the external limiting membrane are also observed, and these often present a granular, frosted or crystalline appearance. They may indicate a senile change, or result from trauma or from retino-choroidal degeneraion. Somewhat similar reflexes may sometimes be present as small frosted patches anterior to the retinal vessels. Linear sinuous, whether appearing in annular form, as straight needles, as broader single sinuous lines, as the tapering, branched double reflexes of Vogt, or in association with traction or pressure folds, in the retina, are probably always pathological. By the use of selected light of long and short wave lengths, it can be shown that intraretinal or true retinal folds may exist with or without the surface reflexes which indicate a corresponding folding of the internal limiting membrane. On the other hand, superficial linear reflexes of various types may occur without evidence of retinal folding. Annular reflexes usually accompany a rounded elevation of the retina due to tumour, hæmorrhage or exudate, but may indicate the presence of rounded depressions; traction folds occur where there is choroido-retinal scarring, or in association with macular hole or cystic degeneraion at the macula; pressure folds in cases of orbital cyst, abscess or neoplasm; and the other linear reflexes in association with papillo-retinal œdema, for example, in retrobulbar neuritis, in hypertensive neuro-retinitis, in contusio bulbi and in anterior uveitis. Punctate reflexes, other than Gunn's dots, are also pathological. They may occur as one variety of “fragmented” surface reflexes, or as evidence of the presence of some highly refractile substance, such as cholesterin or calcium carbonate, in a retinal exudate or other lesion. It is characteristic of the pathological reflexes that they come and go and change their character according to the progress of the pathological condition. The linear reflexes in particular may change from one from to another, and may be finally transformed into surface reflexes of physiological character. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14Fig. 15Fig. 16Fig. 17Fig. 18Fig. 19Fig. 20Fig. 21Fig. 22Fig. 23Fig. 24Fig. 25Fig. 26 PMID:19992307

[Clinical techniques for use in neurological physical examinations. II. Motor and reflex functions].

PubMed

Rodríguez-García, P L; Rodríguez-Pupo, L; Rodríguez-García, D

The aim of this study is to highlight the chief practical aspects of the techniques used in the neurological physical examination of the motor and reflex functions. We recommend clinicians to carry out a brief but consistent and effective exploration in a systematic, flexible and orderly manner to check for abnormalities in the motor and reflex functions of the nervous system. Should any anomalies be detected, then a more detailed and thorough neurological exploration must be performed selectively. We present a detailed review of the practical aspects of the main techniques used in the physical examination of these neurological categories. The motor function is explored using techniques that examine muscle tone, muscle strength, muscle fatigability, hypokinesia, tremor, coordination and gait. Lastly, in this category several manoeuvres that are useful in hysterical or mimicking paralyses are also dealt with. Reflexes to examination are usually divided into: 1. Myotatic reflexes; 2. Cutaneomucous reflexes; 3. Spinal cord or defence automatism reflexes; 4. Posture and attitude reflexes. We also add the study of primitive pathological reflexes, remote reflexes, synkinesias and signs of meningeal irritation. We present a detailed description of the main clinical techniques used in the neurological physical examination of motility and reflexes, as well as an approach that allows them to be performed on adult patients. In addition, we underline the importance of physically examining the nervous system in contemporary medicine and the need to continually perfect the way these techniques are performed in order to achieve an efficient clinical practice.

Decision Space Operations: Campaign Design Aimed at an Adversary’s Decision Making

DTIC Science & Technology

2003-01-01

14 Figure 3: Reflexive control, Initial situation (physical reality ...20 Figure 4: Reflexive control, reality as X imagines it to be...20 Figure 5: Reflexive control, reality as Y imagines it to be .......................................................21 Figure 6: Reflexive

The trigeminocardiac reflex – a comparison with the diving reflex in humans

PubMed Central

Lemaitre, Frederic; Schaller, Bernhard

2015-01-01

The trigeminocardiac reflex (TCR) has previously been described in the literature as a reflexive response of bradycardia, hypotension, and gastric hypermotility seen upon mechanical stimulation in the distribution of the trigeminal nerve. The diving reflex (DR) in humans is characterized by breath-holding, slowing of the heart rate, reduction of limb blood flow and a gradual rise in the mean arterial blood pressure. Although the two reflexes share many similarities, their relationship and especially their functional purpose in humans have yet to be fully elucidated. In the present review, we have tried to integrate and elaborate these two phenomena into a unified physiological concept. Assuming that the TCR and the DR are closely linked functionally and phylogenetically, we have also highlighted the significance of these reflexes in humans. PMID:25995761

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

PubMed Central

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 < 0.038) and was not regulated with muscle contraction, indicating impaired tonic stretch reflex. Phasic-reflex gain in spastic plantar flexors was higher and increased faster with plantar flexor contraction (P < 0.012) than controls (P < 0.023) and higher in dorsi-flexors at lower torques (P < 0.038), primarily because of its increase at rest (P = 0.045), indicating exaggerated phasic stretch reflex especially in more spastic plantar flexors, which showed higher phasic stretch reflex gain than dorsi-flexors (P < 0.032). Spasticity was associated with increased tendon reflex gain (P = 0.002) and decreased threshold (P < 0.001). Mechanically, stiffness in spastic ankles was higher than that in controls across plantar flexion/dorsi-flexion torque levels (P < 0.032), and the more spastic plantar flexors were stiffer than dorsi-flexors at comparable torques (P < 0.031). Increased stiffness in spastic ankles was mainly due to passive stiffness increase (P < 0.001), indicating increased connective tissues/shortened fascicles. Viscous damping in spastic ankles was increased across the plantar flexion torque levels and at lower dorsi-flexion torques, reflecting increased passive viscous damping (P = 0.033). The more spastic plantar flexors showed higher viscous damping than dorsi-flexors at comparable torque levels (P < 0.047). Simultaneous characterizations of reflex and nonreflex changes in spastic hemiparesis may help to evaluate and treat them more effectively. PMID:23636726

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

PubMed

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.

The wild flora biodiversity in pesticide free bufferzones along old hedgerows.

PubMed

Andresen, L C; Nothlev, J; Kristensen, K; Navntoft, S; Johnsen, I

2012-05-01

The natural field margin ecotone from the field border and into a cropped field hosts a diversity of plant species. In conventional cropped fields, biodiversity suffers from fertilizer and pesticide application. In our study at Danish conventional spring-barley fields, we laid out bufferzones with no pesticide application spraying after sowing, with the widths: 24, 12, 6 and 4 m (and control) to the field edge hedgerow. Through one season: plant species number, biodiversity and evenness for each bufferzone at the distances: 18, 9, 5, 2 and 0 m from the hedgerow were significantly affected by distance to the hedge and by width of bufferzone. The bufferzones affected: species number (total of 92 weed species), species diversity (1.27 to 0.44) and species evenness index (0.63 to 0.87), and revealed that the bufferzone of 24 m gave the largest improvementof the field margin for plants. Decreasing the bufferzone widths provided smaller biodiversity and larger evenness of plants at distances larger than the buffer width: the distance at which diversity (Shannons) was reduced by half the difference between hedge- and field diversity was 1.2, 3.1, 6.7, 10.8 and 10.9 m in bufferwidth treatments of 0, 4, 6, 12 and 24 m; likewise, the half-way distance for Smiths and Wilsons evenness index was 1.2, 1.7, 5.4, 14.0 and 30.2 m in the bufferwidth treatments of 0, 4, 6,12 and 24 m. Based on modelled diversity and evenness indexes a positive effect of buffer was evident from 6 m bufferzone. The average diversity over the distances from 0 to 18 m was 0.66, 0.75, 0.98, 1.14 and 1.11 in bufferwidth treatments of 0, 4, 6, 12 and 24 m and the average evenness over the distances from 0 to 18 m was 0.82, 0.80, 0.74, 0.66 and 0.63, in bufferwidth treatments of 0, 4, 6, 12 and 24 m. Furthermore, the accumulated number of species revealed that a bufferzone width of at least 6 m was needed to significantly increase the species richness at all distances between 2 and 18 m. At 18 m distance, the accumulated number of species was 37.1, 39.7, 41.2, 42.4 and 42.7 in bufferwidth treatments of 0, 4, 6, 12 and 24 m.

Enhancement of the intrinsic defecation reflex by mosapride, a 5-HT4 agonist, in chronically lumbosacral denervated guinea pigs.

PubMed

Kojima, Yu; Fujii, Hisao; Katsui, Renta; Nakajima, Yoshiyuki; Takaki, Miyako

2006-10-01

The defecation reflex is composed of rectal distension-evoked rectal (R-R) reflex contractions and synchronous internal anal sphincter (R-IAS) reflex relaxations in guinea pigs. These R-R and R-IAS reflexes are controlled via extrinsic sacral excitatory nerve pathway (pelvic nerves), lumbar inhibitory nerve pathways (colonic nerves) and by intrinsic cholinergic excitatory and nitrergic inhibitory nerve pathways. The effect of mosapride (a prokinetic benzamide) on the intrinsic reflexes, mediated via enteric 5-HT(4) receptors, was evaluated by measuring the mechanical activity of the rectum and IAS in anesthetized guinea pigs using an intrinsic R-R and R-IAS reflex model resulting from chronic (two to nine days) lumbosacral denervation (PITH). In this model, the myenteric plexus remains undamaged and the distribution of myenteric and intramuscular interstitial cells of Cajal is unchanged. Although R-R and R-IAS reflex patterns markedly changed, the reflex indices (reflex pressure or force curve-time integral) of both the R-R contractions and the synchronous R-IAS relaxations were unchanged. The frequency of the spontaneous R and IAS motility was also unchanged. Mosapride (0.1-1.0 mg/kg) dose-dependently increased both intrinsic R-R (maximum: 1.82) and R-IAS reflex indices (maximum: 2.76) from that of the control (1.0) 6-9 days following chronic PITH. The dose-response curve was similar to that in the intact guinea pig, and had shifted to the left from that in the guinea pig after acute PITH. A specific 5-HT(4) receptor antagonist, GR 113808 (1.0 mg/kg), decreased both reflex indices by approximately 50% and antagonized the effect of mosapride 1.0 mg/kg. This was quite different from the result in the intact guinea pig where GR 113808 (1.0 mg/kg) did not affect either of the reflex indices. The present results indicate that mosapride enhanced the intrinsic R-R and R-IAS reflexes and functionally compensated for the deprivation of extrinsic innervation. The actions of mosapride were mediated through endogenously active, intrinsic 5-HT(4) receptors which may be post-synaptically located in the myenteric plexus of the anorectum.

Golden tapetal reflex in male patients with X-linked retinitis pigmentosa. Case report and practical implications.

PubMed

van Osch, L; van Schooneveld, M; Bleekerwagemakers, E M

1990-12-01

The golden tapetal reflex in the ocular fundus is considered pathognomonic of the carrier state in some families with X-linked retinitis pigmentosa (XRP). Reports concerning affected males with this characteristic reflex are scarce. A six-year-old boy with XRP having a tapetal reflex is described. Recently the tapetal reflex has drawn attention in linkage studies. XRP is probably genetically heterogeneous and has at least two genetic forms. The finding of a tapetal reflex in one or more female carriers in a family with XRP may be helpful in differentiating between these two genetic forms.

Suppression of the oculocephalic reflex (doll's eyes phenomenon) in normal full-term babies.

PubMed

Snir, Moshe; Hasanreisoglu, Murat; Hasanreisoglue, Murat; Goldenberg-Cohen, Nitza; Friling, Ronit; Katz, Kalman; Nachum, Yoav; Benjamini, Yoav; Herscovici, Zvi; Axer-Siegel, Ruth

2010-05-01

To determine the precise age of suppression of the oculocephalic reflex in infants and its relationship to specific clinical characteristics. The oculocephalic reflex was prospectively tested in 325 healthy full-term babies aged 1 to 32 weeks attending an orthopedic outpatient clinic. Two ophthalmologists raised the baby's head 30 degrees above horizontal and rapidly rotated it in the horizontal and vertical planes while watching the conjugate eye movement. Suppression of the reflex, by observer agreement, was analyzed in relation to gestational age, postpartum age, postconceptional age, birth weight, and current weight. The data were fitted to a logistic regression model to determine the probability of suppression of the reflex according to the clinical variables. The oculocephalic reflex was suppressed in 75% of babies by the age of 11.5 weeks and in more than 95% of babies aged 20 weeks. Although postpartum age had a greater influence than gestational age, both were significantly correlated with suppression of the reflex (p = 0.01 and p = 0.04, respectively; two-sided t-test). Postpartum age was the best single variable explaining absence of the reflex. On logistic regression with cross-validation, the model including postpartum age and current weight yielded the best results; both these factors were highly correlated with suppression of the reflex (r = 0.74). The oculocephalic reflex is suppressed in the vast majority of normal infants by age 11.5 weeks. The disappearance of the reflex occurs gradually and longitudinally and is part of the normal maturation of the visual system.

Aural Acoustic Stapedius-Muscle Reflex Threshold Procedures to Test Human Infants and Adults.

PubMed

Keefe, Douglas H; Feeney, M Patrick; Hunter, Lisa L; Fitzpatrick, Denis F

2017-02-01

Power-based procedures are described to measure acoustic stapedius-muscle reflex threshold and supra-threshold responses in human adult and infant ears at frequencies from 0.2 to 8 kHz. The stimulus set included five clicks in which four pulsed activators were placed between each pair of clicks, with each stimulus set separated from the next by 0.79 s to allow for reflex decay. Each click response was used to detect the presence of reflex effects across frequency that were elicited by a pulsed broadband-noise or tonal activator in the ipsilateral or contralateral test ear. Acoustic reflex shifts were quantified in terms of the difference in absorbed sound power between the initial baseline click and the later four clicks in each set. Acoustic reflex shifts were measured over a 40-dB range of pulsed activators, and the acoustic reflex threshold was objectively calculated using a maximum 10 likelihood procedure. To illustrate the principles underlying these new reflex tests, reflex shifts in absorbed sound power and absorbance are presented for data acquired in an adult ear with normal hearing and in two infant ears in the initial and follow-up newborn hearing screening exams, one with normal hearing and the other with a conductive hearing loss. The use of absorbed sound power was helpful in classifying an acoustic reflex shift as present or absent. The resulting reflex tests are in use in a large study of wideband clinical diagnosis and monitoring of middle-ear and cochlear function in infant and adult ears.

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

ERIC Educational Resources Information Center

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…

Reflections on the challenges of understanding racial, cultural and sexual differences in couple relationship research

PubMed Central

Gabb, Jacqui; Singh, Reenee

2015-01-01

In the field of systemic psychotherapy there has been much recent interest in the areas of culture and reflexivity, and in working with couples. In this article we reflect on the process of conducting research in these areas. Drawing on findings from a large, national, empirical mixed-methods study on long-term relationships, we use two examples from the data to illustrate the complexity of researching across racial, cultural and sexual differences, in terms of research design and sampling, fieldwork and research practice, and making sense of multidimensional data. We point to findings that suggest that notions of coupledom are culturally constructed and thus challenge straightforward ideas of the procreative, sexually active couple dyad, separate from intergenerational extended families. The clinical significance of the findings for both lesbian, gay, bisexual or queer and culturally diverse couples and families are discussed. Practitioner points Cultural or racial matching is not a sufficient condition for engagement and empathy with couples and families. Critical reflexivity about similarity and difference is essential in cross-cultural systemic practice. ‘The couple’ and its distance from the extended family may be defined differently in different cultures. One research tool used in this project, the emotion map, appears to have utility in clinical practice with couples and families. PMID:25820766

Biosonar behaviour of free-ranging porpoises.

PubMed

Akamatsu, Tomonari; Wang, Ding; Wang, Kexiong; Naito, Yasuhiko

2005-04-22

Detecting objects in their paths is a fundamental perceptional function of moving organisms. Potential risks and rewards, such as prey, predators, conspecifics or non-biological obstacles, must be detected so that an animal can modify its behaviour accordingly. However, to date few studies have considered how animals in the wild focus their attention. Dolphins and porpoises are known to actively use sonar or echolocation. A newly developed miniature data logger attached to a porpoise allows for individual recording of acoustical search efforts and inspection distance based on echolocation. In this study, we analysed the biosonar behaviour of eight free-ranging finless porpoises (Neophocaena phocaenoides) and demonstrated that these animals inspect the area ahead of them before swimming silently into it. The porpoises inspected distances up to 77 m, whereas their swimming distance without using sonar was less than 20 m. The inspection distance was long enough to ensure a wide safety margin before facing real risks or rewards. Once a potential prey item was detected, porpoises adjusted their inspection distance from the remote target throughout their approach.

Research on cardiovascular disease prediction based on distance metric learning

NASA Astrophysics Data System (ADS)

Ni, Zhuang; Liu, Kui; Kang, Guixia

2018-04-01

Distance metric learning algorithm has been widely applied to medical diagnosis and exhibited its strengths in classification problems. The k-nearest neighbour (KNN) is an efficient method which treats each feature equally. The large margin nearest neighbour classification (LMNN) improves the accuracy of KNN by learning a global distance metric, which did not consider the locality of data distributions. In this paper, we propose a new distance metric algorithm adopting cosine metric and LMNN named COS-SUBLMNN which takes more care about local feature of data to overcome the shortage of LMNN and improve the classification accuracy. The proposed methodology is verified on CVDs patient vector derived from real-world medical data. The Experimental results show that our method provides higher accuracy than KNN and LMNN did, which demonstrates the effectiveness of the Risk predictive model of CVDs based on COS-SUBLMNN.

The Use of an Alternative Extraoral Periapical Technique for Patients with Severe Gag Reflex

PubMed Central

e Silva, Mauro Henrique Chagas; Santos, Mariane Floriano Lopes; de Lima, Carolina Oliveira; Campos, Celso Neiva

2016-01-01

Gag reflex is a physiologic mechanism that promotes contraction of the muscles of the tongue and pharyngeal walls. Different factors, including intraoral radiographic films and sensors, may trigger this reflex. Patients with severe gag reflex may not be able to tolerate the presence of intraoral radiographic films or sensors during root canal therapy (RCT). This factor may prevent an appropriate intraoral radiograph, which is important in RCT. Different approaches have been used to facilitate dental procedures in patients suffering from severe gag reflex. The use of an extraoral radiographic technique is an alternative method to obtain working length confirmation in patients with severe gag reflex. In this report of 2 cases, the use of an extraoral radiographic technique as an alternative approach during RCT in patients with severe gag reflex associated with phobic behavior and trismus was successfully demonstrated. PMID:27547474

The parallel programming of voluntary and reflexive saccades.

PubMed

Walker, Robin; McSorley, Eugene

2006-06-01

A novel two-step paradigm was used to investigate the parallel programming of consecutive, stimulus-elicited ('reflexive') and endogenous ('voluntary') saccades. The mean latency of voluntary saccades, made following the first reflexive saccades in two-step conditions, was significantly reduced compared to that of voluntary saccades made in the single-step control trials. The latency of the first reflexive saccades was modulated by the requirement to make a second saccade: first saccade latency increased when a second voluntary saccade was required in the opposite direction to the first saccade, and decreased when a second saccade was required in the same direction as the first reflexive saccade. A second experiment confirmed the basic effect and also showed that a second reflexive saccade may be programmed in parallel with a first voluntary saccade. The results support the view that voluntary and reflexive saccades can be programmed in parallel on a common motor map.

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

PubMed

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.

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

ERIC Educational Resources Information Center

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…

On Reflection: Is Reflexivity Necessarily Beneficial in Intercultural Education?

ERIC Educational Resources Information Center

Blasco, Maribel

2012-01-01

This article explores how the concept of reflexivity is used in intercultural education. Reflexivity is often presented as a key learning goal in acquiring intercultural competence (ICC). Yet, reflexivity can be defined in different ways, and take different forms across time and space, depending on the concepts of selfhood that prevail and how…

The Limits of Institutional Reflexivity in Bulgarian Universities

ERIC Educational Resources Information Center

Slantcheva, Snejana

2004-01-01

This article focuses on the notion of institutional reflexivity. Its theoretical framework is based on the views of a group of sociologists--Anthony Giddens, Ulrich Beck, Scott Lash--who developed the concept of reflexive modernization. The article applies the notion of institutional reflexivity to the field of higher education and reviews the…

The Pivotal Role of the Parieto-Occipital Lobe in Card Game-Induced Reflex Epilepsy: A Voxel-Based Morphometry Study.

PubMed

Park, Kang Min; Kim, Sung Eun; Lee, Byung In

2016-01-01

The pathogenesis of card game-induced reflex epilepsy has not been determined so far. The aim of this study was to evaluate structural abnormalities using voxel-based morphometry (VBM) analysis, which may give some clue about the pathogenesis in card game-induced reflex epilepsy. The 3 subjects were diagnosed with card game-induced reflex epilepsy. Evaluation involved a structured interview to obtain clinical information and brain MRI. In VBM analysis, Statistical Parametric Mapping 8 running on the MATLAB platform was employed to analyze the structural differences between patients with card game-induced reflex epilepsy and age- and sex-matched control subjects. The results of VBM analysis revealed that patients with card game-induced reflex epilepsy had significantly increased gray matter volume in the right occipital and parietal lobe. However, there were no structures with decreased gray matter volume in patients with card game-induced reflex epilepsy compared with control subjects. In addition, we found that the patients with card game-induced reflex epilepsy had onset of seizures in adulthood rather than in adolescence, and all of the patients were men. The parieto-occipital lobes might be partially involved in the neuronal network responsible for card game-induced reflex epilepsy. © 2016 S. Karger AG, Basel.

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

PubMed

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.

Dendritic spine dysgenesis contributes to hyperreflexia after spinal cord injury

PubMed Central

Bandaru, Samira P.; Liu, Shujun; Waxman, Stephen G.

2014-01-01

Hyperreflexia and spasticity are chronic complications in spinal cord injury (SCI), with limited options for safe and effective treatment. A central mechanism in spasticity is hyperexcitability of the spinal stretch reflex, which presents symptomatically as a velocity-dependent increase in tonic stretch reflexes and exaggerated tendon jerks. In this study we tested the hypothesis that dendritic spine remodeling within motor reflex pathways in the spinal cord contributes to H-reflex dysfunction indicative of spasticity after contusion SCI. Six weeks after SCI in adult Sprague-Dawley rats, we observed changes in dendritic spine morphology on α-motor neurons below the level of injury, including increased density, altered spine shape, and redistribution along dendritic branches. These abnormal spine morphologies accompanied the loss of H-reflex rate-dependent depression (RDD) and increased ratio of H-reflex to M-wave responses (H/M ratio). Above the level of injury, spine density decreased compared with below-injury spine profiles and spine distributions were similar to those for uninjured controls. As expected, there was no H-reflex hyperexcitability above the level of injury in forelimb H-reflex testing. Treatment with NSC23766, a Rac1-specific inhibitor, decreased the presence of abnormal dendritic spine profiles below the level of injury, restored RDD of the H-reflex, and decreased H/M ratios in SCI animals. These findings provide evidence for a novel mechanistic relationship between abnormal dendritic spine remodeling in the spinal cord motor system and reflex dysfunction in SCI. PMID:25505110

Comparison of single bout effects of bicycle training versus locomotor training on paired reflex depression of the soleus H-reflex after motor incomplete spinal cord injury.

PubMed

Phadke, Chetan P; Flynn, Sheryl M; Thompson, Floyd J; Behrman, Andrea L; Trimble, Mark H; Kukulka, Carl G

2009-07-01

To examine paired reflex depression changes post 20-minute bout each of 2 training environments: stationary bicycle ergometer training (bicycle training) and treadmill with body weight support and manual assistance (locomotor training). Pretest-posttest repeated-measures. Locomotor laboratory. Motor incomplete SCI (n=12; mean, 44+/-16y); noninjured subjects (n=11; mean, 30.8+/-8.3y). All subjects received each type of training on 2 separate days. Paired reflex depression at different interstimulus intervals (10 s, 1 s, 500 ms, 200 ms, and 100 ms) was measured before and after both types of training. (1) Depression was significantly less post-SCI compared with noninjured subjects at all interstimulus intervals and (2) post-SCI at 100-millisecond interstimulus interval: reflex depression significantly increased postbicycle training in all SCI subjects and in the chronic and spastic subgroups (P<.05). Phase-dependent regulation of reflex excitability, essential to normal locomotion, coordinated by pre- and postsynaptic inhibitory processes (convergent action of descending and segmental inputs onto spinal circuits) is impaired post-SCI. Paired reflex depression provides a quantitative assay of inhibitory processes contributing to phase-dependent changes in reflex excitability. Because bicycle training normalized reflex depression, we propose that bicycling may have a potential role in walking rehabilitation, and future studies should examine the long-term effects on subclinical measures of reflex activity and its relationship to functional outcomes.

Impact of Resection Margin Distance on Survival of Pancreatic Cancer: A Systematic Review and Meta-Analysis

PubMed Central

Kim, Kyung Su; Kwon, Jeanny; Kim, Kyubo; Chie, Eui Kyu

2017-01-01

Purpose While curative resection is the only chance of cure in pancreatic cancer, controversies exist about the impact of surgical margin status on survival. Non-standardized pathologic report and different criteria on the R1 status made it difficult to implicate adjuvant therapy after resection based on the margin status. We evaluated the influence of resection margins on survival by meta-analysis. Materials and Methods We thoroughly searched electronic databases of PubMed, EMBASE, and Cochrane Library. We included studies reporting survival outcomes with different margin status: involved margin (R0 mm), margin clearance with ≤ 1 mm (R0-1 mm), and margin with > 1 mm (R>1 mm). Hazard ratio (HR) for overall survival was extracted, and a random-effects model was used for pooled analysis. Results A total of eight retrospective studies involving 1,932 patients were included. Pooled HR for overall survival showed that patients with R>1 mm had reduced risk of death than those with R0-1 mm (HR, 0.74; 95% confidence interval [CI], 0.61 to 0.88; p=0.001). In addition, patients with R0-1 mm had reduced risk of death than those with R0 mm (HR, 0.81; 95% CI, 0.72 to 0.91; p < 0.001). There was no heterogeneity between the included studies (I2 index, 42% and 0%; p=0.10 and p=0.82, respectively). Conclusion Our results suggest that stratification of the patients based on margin status is warranted in the clinical trials assessing the role of adjuvant treatment for pancreatic cancer. PMID:27561314

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

PubMed

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 findings also apply to long-term adaption to the exoskeleton.

Respiratory kinematic and airflow differences between reflex and voluntary cough in healthy young adults

PubMed Central

Brandimore, Alexandra E.; Troche, Michelle S.; Huber, Jessica E.; Hegland, Karen W.

2015-01-01

Background: Cough is a defensive behavior that can be initiated in response to a stimulus in the airway (reflexively), or on command (voluntarily). There is evidence to suggest that physiological differences exist between reflex and voluntary cough; however, the output (mechanistic and airflow) differences between the cough types are not fully understood. Therefore, the aims of this study were to determine the lung volume, respiratory kinematic, and airflow differences between reflex and voluntary cough in healthy young adults. Methods: Twenty-five participants (14 female; 18–29 years) were recruited for this study. Participants were evaluated using respiratory inductance plethysmography calibrated with spirometry. Experimental procedures included: (1) respiratory calibration, (2) three voluntary sequential cough trials, and (3) three reflex cough trials induced with 200 μM capsaicin. Results: Lung volume initiation (LVI; p = 0.003) and lung volume excursion (LVE; p < 0.001) were significantly greater for voluntary cough compared to reflex cough. The rib cage and abdomen significantly influenced LVI for voluntary cough (p < 0.001); however, only the rib cage significantly impacted LVI for reflex cough (p < 0.001). LVI significantly influenced peak expiratory flow rate (PEFR) for voluntary cough (p = 0.029), but not reflex cough (p = 0.610). Discussion: Production of a reflex cough results in significant mechanistic and airflow differences compared to voluntary cough. These findings suggest that detection of a tussigenic stimulus modifies motor aspects of the reflex cough behavior. Further understanding of the differences between reflex and voluntary cough in older adults and in persons with dystussia (cough dysfunction) will be essential to facilitate the development of successful cough treatment paradigms. PMID:26500560

Trigeminal Proprioception Evoked by Strong Stretching of the Mechanoreceptors in Müller's Muscle Induces Reflex Contraction of the Orbital Orbicularis Oculi Slow-Twitch Muscle Fibers.

PubMed

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

2014-01-01

The mixed orbicularis oculi muscle lacks an intramuscular proprioceptive system such as muscle spindles, to induce reflex contraction of its slow-twitch fibers. We evaluated whether the mechanoreceptors in Müller's muscle function as extrinsic mechanoreceptors to induce reflex contraction of the slow-twitch fibers of the orbicularis oculi in addition to those of the levator and frontalis muscles. We evaluated in patients with aponeurosis-disinserted blepharoptosis whether strong stretching of the mechanoreceptors in Müller's muscle from upgaze with unilateral lid load induced reflex contraction of the orbicularis oculi slow-twitch fibers and whether anesthesia of Müller's muscle precluded the contraction. We compared the electromyographic responses of the bilateral orbicularis oculi muscles to unilateral intraoperative direct stimulation of the trigeminal proprioceptive nerve with those to unilateral transcutaneous electrical stimulation of the supraorbital nerve. Upgaze with a unilateral 3-g lid load induced reflex contraction of the bilateral orbicularis oculi muscles with ipsilateral dominance. Anesthesia of Müller's muscle precluded the reflex contraction. The orbicularis oculi reflex evoked by stimulation of the trigeminal proprioceptive nerve differed from that by electrical stimulation of the supraorbital nerve in terms of the intensity of current required to induce the reflex, the absence of R1, and duration. The mechanoreceptors in Müller's muscle functions as an extramuscular proprioceptive system to induce reflex contraction of the orbital orbicularis oculi slow-twitch fibers. Whereas reflex contraction of the pretarsal orbicularis fast-twitch fibers functions in spontaneous or reflex blinking, that of the orbital orbicularis oculi slow-twitch fibers may factor in grimacing and blepharospasm.

Trigeminal Proprioception Evoked by Strong Stretching of the Mechanoreceptors in Müller's Muscle Induces Reflex Contraction of the Orbital Orbicularis Oculi Slow-Twitch Muscle Fibers

PubMed Central

Ban, Ryokuya; Ban, Midori; Yuzuriha, Shunsuke

2014-01-01

Objective: The mixed orbicularis oculi muscle lacks an intramuscular proprioceptive system such as muscle spindles, to induce reflex contraction of its slow-twitch fibers. We evaluated whether the mechanoreceptors in Müller's muscle function as extrinsic mechanoreceptors to induce reflex contraction of the slow-twitch fibers of the orbicularis oculi in addition to those of the levator and frontalis muscles. Methods: We evaluated in patients with aponeurosis-disinserted blepharoptosis whether strong stretching of the mechanoreceptors in Müller's muscle from upgaze with unilateral lid load induced reflex contraction of the orbicularis oculi slow-twitch fibers and whether anesthesia of Müller's muscle precluded the contraction. We compared the electromyographic responses of the bilateral orbicularis oculi muscles to unilateral intraoperative direct stimulation of the trigeminal proprioceptive nerve with those to unilateral transcutaneous electrical stimulation of the supraorbital nerve. Results: Upgaze with a unilateral 3-g lid load induced reflex contraction of the bilateral orbicularis oculi muscles with ipsilateral dominance. Anesthesia of Müller's muscle precluded the reflex contraction. The orbicularis oculi reflex evoked by stimulation of the trigeminal proprioceptive nerve differed from that by electrical stimulation of the supraorbital nerve in terms of the intensity of current required to induce the reflex, the absence of R1, and duration. Conclusions: The mechanoreceptors in Müller's muscle functions as an extramuscular proprioceptive system to induce reflex contraction of the orbital orbicularis oculi slow-twitch fibers. Whereas reflex contraction of the pretarsal orbicularis fast-twitch fibers functions in spontaneous or reflex blinking, that of the orbital orbicularis oculi slow-twitch fibers may factor in grimacing and blepharospasm. PMID:25210572

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.

PubMed

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.

Contributions of Altered Stretch Reflex Coordination to Arm Impairments Following Stroke

PubMed Central

Ravichandran, Vengateswaran J.; Krutky, Matthew A.; Perreault, Eric J.

2010-01-01

Patterns of stereotyped muscle coactivation, clinically referred to as synergies, emerge following stroke and impair arm function. Although researchers have focused on cortical contributions, there is growing evidence that altered stretch reflex pathways may also contribute to impairment. However, most previous reflex studies have focused on passive, single-joint movements without regard to their coordination during volitional actions. The purpose of this study was to examine the effects of stroke on coordinated activity of stretch reflexes elicited in multiple arm muscles following multijoint perturbations. We hypothesized that cortical injury results in increased stretch reflexes of muscles characteristic of the abnormal flexor synergy during active arm conditions. To test this hypothesis, we used a robot to apply position perturbations to impaired arms of 10 stroke survivors and dominant arms of 8 healthy age-matched controls. Corresponding reflexes were assessed during volitional contractions simulating different levels of gravitational support, as well as during voluntary flexion and extension of the elbow and shoulder. Reflexes were quantified by average rectified surface electromyogram, recorded from eight muscles spanning the elbow and shoulder. Reflex coordination was quantified using an independent components analysis. We found stretch reflexes elicited in the stroke group were significantly less sensitive to changes in background muscle activation compared with those in the control group (P < 0.05). We also observed significantly increased reflex coupling between elbow flexor and shoulder abductor–extensor muscles in stroke subjects relative to that in control subjects. This increased coupling was present only during volitional tasks that required elbow flexion (P < 0.001), shoulder extension (P < 0.01), and gravity opposition (P < 0.01), but not during the “no load” condition. During volitional contractions, reflex amplitudes scaled with the level of impairment, as assessed by Fugl-Meyer scores (r2 = 0.63; P < 0.05). We conclude that altered reflex coordination is indicative of motor impairment level and may contribute to impaired arm function following stroke. PMID:20962072

Neuroanatomical basis of Sandifer's syndrome: a new vagal reflex?

PubMed

Cerimagic, Denis; Ivkic, Goran; Bilic, Ervina

2008-01-01

Sandifer's syndrome is a gastrointestinal disorder with neurological features. It is characterized by reflex torticollis following deglutition in patients with gastroesophageal reflux and/or hiatal hernia. The authors believe that neurological manifestations of the syndrome are the consequence of vagal reflex with the reflex center in nucleus tractus solitarii (NTS). Three models for the neuroanatomical basis of the hypothetic reflex arc are presented. In the first one the hypothetic reflex arc is based on the classic hypothesis of two components nervus accessorius (n.XI) - radix cranialis (RC) and radix spinalis (RS) The nervous impulses are transmitted by nervus vagus (n.X) general visceral afferent (GVA) fibers to NTS situated in medulla oblongata, then by interneuronal connections on nucleus ambiguus (NA) and nucleus dorsalis nervi vagi (NDX). Special visceral efferent fibers (SVE) impulses from NA are in part transferred to n.XI ramus externus (RE) (carrying the majority of general somatic efferent (GSE) fibers) via hypothetic anastomoses in the region of foramen jugulare. This leads to contraction of trapezius and sternocleidomastoideus muscles, and the occurrence of intermittent torticollis. In the second suggested neuroanatomical model the hypothetic reflex arc is organized in the absence of n.XI RC, the efferent part of the reflex arc continues as NA, which is motor nucleus of nervus glossopharyngeus (n.IX) and n.X in this case while distal roots of n.XI that appear at the level of the olivary nucleus lower edge represent n.X roots. In the third presented model the hypothetic reflex arc includes no jugular transfer and could be realized via interneuronal connections directly from NTS to the spinal motoneurons within nucleus radicis spinalis nervi accessorii (NRS n.XI) or from NA to NRS n.XI. The afferent segment of the postulated reflex arc in all three models is mediated via n.X. We conclude that Sandifer's syndrome is a clinical manifestation of another vagal reflex that could be termed a "vagocervical" or "esophagocervical" reflex, based on the neuroanatomical hypotheses elaborated in this paper.

Human ocular responses to translation of the observer and of the scene: dependence on viewing distance.

PubMed

Busettini, C; Miles, F A; Schwarz, U; Carl, J R

1994-01-01

Recent experiments on monkeys have indicated that the eye movements induced by brief translation of either the observer or the visual scene are a linear function of the inverse of the viewing distance. For the movements of the observer, the room was dark and responses were attributed to a translational vestibulo-ocular reflex (TVOR) that senses the motion through the otolith organs; for the movements of the scene, which elicit ocular following, the scene was projected and adjusted in size and speed so that the retinal stimulation was the same at all distances. The shared dependence on viewing distance was consistent with the hypothesis that the TVOR and ocular following are synergistic and share central pathways. The present experiments looked for such dependencies on viewing distance in human subjects. When briefly accelerated along the interaural axis in the dark, human subjects generated compensatory eye movements that were also a linear function of the inverse of the viewing distance to a previously fixated target. These responses, which were attributed to the TVOR, were somewhat weaker than those previously recorded from monkeys using similar methods. When human subjects faced a tangent screen onto which patterned images were projected, brief motion of those images evoked ocular following responses that showed statistically significant dependence on viewing distance only with low-speed stimuli (10 degrees/s). This dependence was at best weak and in the reverse direction of that seen with the TVOR, i.e., responses increased as viewing distance increased. We suggest that in generating an internal estimate of viewing distance subjects may have used a confounding cue in the ocular-following paradigm--the size of the projected scene--which was varied directly with the viewing distance in these experiments (in order to preserve the size of the retinal image). When movements of the subject were randomly interleaved with the movements of the scene--to encourage the expectation of ego-motion--the dependence of ocular following on viewing distance altered significantly: with higher speed stimuli (40 degrees/s) many responses (63%) now increased significantly as viewing distance decreased, though less vigorously than the TVOR. We suggest that the expectation of motion results in the subject placing greater weight on cues such as vergence and accommodation that provide veridical distance information in our experimental situation: cue selection is context specific.

Nerve regeneration in nerve grafts conditioned by vibration exposure.

PubMed

Bergman, S; Widerberg, A; Danielsen, N; Lundborg, G; Dahlin, L B

1995-01-01

Regeneration distances were studied in nerves from vibration-exposed limbs. One hind limb of anaesthetized rats was attached to a vibration exciter and exposed to vibration (80 Hz/32 m/s2) for 5 h/day for 2 or 5 days. Seven days after the latest vibration period a 10-mm long nerve graft was taken from the vibrated sciatic nerve and sutured into a corresponding defect in the con-tralateral sciatic nerve and vice versa, thereby creating two different models within the same animal: (i) regeneration from a freshly transected unvibrated nerve into a vibrated graft and (ii) regeneration from a vibrated nerve into a fresh nerve graft (vibrated recipient side). Four, 6 or 8 days postoperatively (p.o.) the distances achieved by the regenerating axons were determined using the pinch reflex test. Two days of vibration did not influence the regeneration, but 5 days of vibration reduced the initial delay period and a slight reduction of regeneration rate was observed. After 5 days of vibration an increased regeneration distance was observed in both models at day 4 p.o. and at day 6 p.o. in vibrated grafts. This study demonstrates that vibration can condition peripheral nerves and this may be caused by local changes in the peripheral nerve trunk and in the neuron itself.

Passive margins getting squeezed in the mantle convection vice

NASA Astrophysics Data System (ADS)

Yamato, Philippe; Husson, Laurent; Becker, Thorsten W.; Pedoja, Kevin

2013-12-01

margins often exhibit uplift, exhumation, and tectonic inversion. We speculate that the compression in the lithosphere gradually increased during the Cenozoic, as seen in the number of mountain belts found at active margins during that period. Less clear is how that compression increase affects passive margins. In order to address this issue, we design a 2-D viscous numerical model wherein a lithospheric plate rests above a weaker mantle. It is driven by a mantle conveyor belt, alternatively excited by a lateral downwelling on one side, an upwelling on the other side, or both simultaneously. The lateral edges of the plate are either free or fixed, representing the cases of free convergence, and collision (or slab anchoring), respectively. This distinction changes the upper mechanical boundary condition for mantle circulation and thus, the stress field. Between these two regimes, the flow pattern transiently evolves from a free-slip convection mode toward a no-slip boundary condition above the upper mantle. In the second case, the lithosphere is highly stressed horizontally and deforms. For a constant total driving force, compression increases drastically at passive margins if upwellings are active. Conversely, if downwellings alone are activated, compression occurs at short distances from the trench and extension prevails elsewhere. These results are supported by Earth-like models that reveal the same pattern, where active upwellings are required to excite passive margins compression. Our results substantiate the idea that compression at passive margins is in response to the underlying mantle flow that is increasingly resisted by the Cenozoic collisions.

Digital Muslimas: ICT Skills of Females in Middle Eastern Countries

ERIC Educational Resources Information Center

Primo, L. Heidi

2010-01-01

This article examines women in Islamic countries with regard to sustainable futures, equity, and social justice. Some barriers to ICT use for women in the Middle East include access to computers, gender discrimination by employers, marginalized political participation, high rates of illiteracy, and lack of independence. Distance education offers a…

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

ERIC Educational Resources Information Center

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…

Introducing Reflexivity to Evaluation Practice: An In-Depth Case Study

ERIC Educational Resources Information Center

van Draanen, Jenna

2017-01-01

There is currently a paucity of literature in the field of evaluation regarding the practice of reflection and reflexivity and a lack of available tools to guide this practice--yet using a reflexive model can enhance evaluation practice. This paper focuses on the methods and results of a reflexive inquiry that was conducted during a participatory…

The stiff-man syndrome: new pathophysiological aspects from abnormal exteroceptive reflexes and the response to clomipramine, clonidine, and tizanidine.

PubMed Central

Meinck, H M; Ricker, K; Conrad, B

1984-01-01

Neurophysiological investigations of a patient suffering from the stiff-man syndrome revealed that exteroceptive reflexes, in particular those elicited from the skin, were excessively enhanced. In contrast, no abnormalities were found within the monosynaptic reflex arc. Clomipramine injection severely aggravated the clinical symptoms whereas diazepam, clonidine, and tizanidine decreased both muscular stiffness and abnormal exteroceptive reflexes. The hypothesis is put forward that the stiff-man syndrome is a disorder of descending brain-stem systems which exert a net inhibitory control on axial and limb girdle muscle tone as well as on exteroceptive reflex transmission. Detection of abnormal exteroceptive reflex activity in conjunction with neuropharmacological testing might help in the diagnosis of this rare disease. PMID:6707674

[Reflex seizures, cinema and television].

PubMed

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.

Tendon reflex is suppressed during whole-body vibration.

PubMed

Karacan, Ilhan; Cidem, Muharrem; Yilmaz, Gizem; Sebik, Oguz; Cakar, Halil Ibrahim; Türker, Kemal Sıtkı

2016-10-01

In this study we have investigated the effect of whole body vibration (WBV) on the tendon reflex (T-reflex) amplitude. Fifteen young adult healthy volunteer males were included in this study. Records of surface EMG of the right soleus muscle and accelerometer taped onto the right Achilles tendon were obtained while participant stood upright with the knees in extension, on the vibration platform. Tendon reflex was elicited before and during WBV. Subjects completed a set of WBV. Each WBV set consisted of six vibration sessions using different frequencies (25, 30, 35, 40, 45, 50Hz) applied randomly. In each WBV session the Achilles tendon was tapped five times with a custom-made reflex hammer. The mean peak-to-peak (PP) amplitude of T-reflex was 1139.11±498.99µV before vibration. It decreased significantly during WBV (p<0.0001). The maximum PP amplitude of T-reflex was 1333±515μV before vibration. It decreased significantly during WBV (p<0.0001). No significant differences were obtained in the mean acceleration values of Achilles tendon with tapping between before and during vibration sessions. This study showed that T-reflex is suppressed during WBV. T-reflex suppression indicates that the spindle primary afferents must have been pre-synaptically inhibited during WBV similar to the findings in high frequency tendon vibration studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Intrapartum Synthetic Oxytocin Reduce the Expression of Primitive Reflexes Associated with Breastfeeding

PubMed Central

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

2015-01-01

Abstract Aim: 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. Materials and Methods: 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. Results: 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). Conclusions: Intrapartum oxytocin administration might inhibit the expression of several primitive neonatal reflexes associated with breastfeeding. This correlation does not seem to be dose-dependent. PMID:25785487

Manual therapy directed at the knee or lumbopelvic region does not influence quadriceps spinal reflex excitability.

PubMed

Grindstaff, Terry L; Pietrosimone, Brian G; Sauer, Lindsay D; Kerrigan, D Casey; Patrie, James T; Hertel, Jay; Ingersoll, Christopher D

2014-08-01

Manual therapies, directed to the knee and lumbopelvic region, have demonstrated the ability to improve neuromuscular quadriceps function in individuals with knee pathology. It remains unknown if manual therapies may alter impaired spinal reflex excitability, thus identifying a potential mechanism in which manual therapy may improve neuromuscular function following knee injury. To determine the effect of local and distant mobilisation/manipulation interventions on quadriceps spinal reflex excitability. Seventy-five individuals with a history of knee joint injury and current quadriceps inhibition volunteered for this study. Participants were randomised to one of five intervention groups: lumbopelvic manipulation (grade V), lumbopelvic manipulation positioning (no thrust), grade IV patellar mobilisation, grade I patellar mobilisation, and control (no treatment). Changes in spinal reflex excitability were quantified by assessing the Hoffmann reflex (H-reflex), presynaptic, and postsynaptic excitability. A hierarchical linear-mixed model for repeated measures was performed to compare changes in outcome variables between groups over time (pre, post 0, 30, 60, 90 min). There were no significant differences in H-reflex, presynaptic, or postsynaptic excitability between groups across time. Manual therapies directed to the knee or lumbopelvic region did not acutely change quadriceps spinal reflex excitability. Although manual therapies may improve impairments and functional outcomes the underlying mechanism does not appear to be related to changes in spinal reflex excitability. Copyright © 2014 Elsevier Ltd. All rights reserved.

No evidence hip joint angle modulates intrinsically produced stretch reflex in human hopping.

PubMed

Gibson, W; Campbell, A; Allison, G

2013-09-01

Motor output in activities such as walking and hopping is suggested to be mediated neurally by purported stretch reflex augmentation of muscle output. Reflex EMG activity during these tasks has been frequently investigated in the soleus muscle; with alterations in reflex amplitude being associated with changes in hip joint angle/phase of the gait cycle. Previous work has focussed on reflex activity induced by an artificial perturbation or by induction of H-reflexes. As such, it is currently unknown if stretch reflex activity induced intrinsically (as part of the task) is modulated by changes in hip joint angle. This study investigated whether hip joint angle modulated reflex EMG 'burst' activity during a hopping task performed on a custom-built partially reclined sleigh. Ten subjects participated; EMG and kinematic data (VICON motor capture system) was collected for each hop cycle. Participants completed 5 sets of 30s of self-paced hopping in (1) hip neutral and (2) hip 60° flexion conditions. There was no difference in EMG 'burst' activity or in sagittal plane kinematics (knee/ankle) in the hopping task between the two conditions. The results indicate that during a functional task such as hopping, changes in hip angle do not alter the stretch reflex-like activity associated with landing. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of noxious electrical stimulation of the peroneal nerve on stretch reflex activity of the hamstring muscle in rats: possible implications of neuronal mechanisms in the development of tight hamstrings in lumbar disc herniation.

PubMed

Hirayama, Jiro; Yamagata, Masatsune; Takahashi, Kazuhisa; Moriya, Hideshige

2005-05-01

The effect of noxious electrical stimulation of the peroneal nerve on the stretch reflex electromyogram activity of the hamstring muscle (semitendinous) was studied. To verify the following hypothetical mechanisms underlying tight hamstrings in lumbar disc herniation: stretch reflex muscle activity of hamstrings is increased by painful inputs from an injured spinal nerve root and the increased stretch reflex muscle activity is maintained by central sensitization. It is reported that stretch reflex activity of the trunk muscles is induced by noxious stimulation of the sciatic nerve and maintained by central sensitization. In spinalized rats (transected spinal cord), the peroneal nerve was stimulated electrically as a conditioning stimulus. Stretch reflex electromyogram activity of the semitendinous muscle was recorded before and after the conditioning stimulus. Even after electrical stimulation was terminated, an increased stretch reflex activity of the hamstring muscle was observed. It is likely that a central sensitization mechanism at the spinal cord level was involved in the increased reflex activity. Central sensitization may play a part in the neuronal mechanisms of tight hamstrings in lumbar disc herniation.

Anatomically remote muscle contraction facilitates patellar tendon reflex reinforcement while mental activity does not: a within-participants experimental trial.

PubMed

Passmore, Steven R; Bruno, Paul A

2012-09-07

The Jendrassik maneuver (JM) is a remote facilitation muscular contraction shown to affect amplitude and temporal components of the human stretch reflex. Conflicting theoretical models exist regarding the neurological mechanism related to its ability to reinforce reflex parameters. One mechanism involves the gamma motoneurons of the fusimotor system, which are subject to both physical and mental activity. A second mechanism describes reduced alpha motoneuron presynaptic inhibition, which is not subject to mental activity. In the current study, we determined if mental activity could be used to create a reflex facilitation comparable to a remote muscle contraction. Using a within-participants design, we investigated the relative effect of the JM and a successfully employed mental task (Stroop task) on the amplitude and temporal components of the patellar tendon reflex. We found that the addition of mental activity had no influence on the patellar tendon reflex parameters measured, while the JM provided facilitation (increased reflex amplitude, decreased total reflex time). The findings from this study support the view that the mechanism for the JM is a reduction in presynaptic inhibition of alpha motoneurons as it is influenced by physical and not mental activity.

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

PubMed

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.

Reflex responses of lip muscles in young and older women.

PubMed

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.

Grammar of Binding in the languages of the world: Innate or learned?

PubMed

Cole, Peter; Hermon, Gabriella; Yanti

2015-08-01

Languages around the world often appear to manifest nearly identical grammatical properties, but, at the same time, the grammatical differences can also be great, sometimes even seeming to support Joos's (1958) claim that "languages can differ from each other without limit and in unpredictable way" (p. 96). This state of affairs provides a puzzle for both nativist approaches to language like Generative Grammar that posit a fixed "Universal Grammar", and for approaches that minimize the contribution of innate grammatical structure. We approach this puzzling state of affairs by looking at one area of grammar, "Binding", the system of local and long distance anaphoric elements in a language. This is an area of grammar that has long been central to the Generative approach to language structure. We compare the anaphoric systems found in "familiar" (European-like) languages that contain dedicated classes of bound and free anaphors (pronouns and reflexives) with the anaphoric systems in endangered Austronesian languages of Indonesia, languages in which there is overlap or no distinction between pronouns and reflexives (Peranakan Javanese and Jambi Malay). What is of special interest about Jambi anaphora is not only that conservative dialects of Jambi Malay do not distinguish between pronouns and reflexives, but that Jambi anaphora appear to constitute a live snapshot of a unitary class of anaphora in the process of grammaticalization as a distinct system of pronouns and reflexives. We argue that the facts of Jambi anaphora cannot be explained by theories positing a Universal Grammar of Binding. Thus, these facts provide evidence that complex grammatical systems like Binding cannot be innate. Our results from Austronesian languages are confirmed by data from signed and creole languages. Our conclusion is that the human language learning capacity must include the ability to model the full complexity found in the syntax of the world's languages. From the perspective of child language acquisition, these conclusions suggest that Universal Grammar does not provide a general solution to the problem of poverty of the stimulus, and the solution to that problem must reside at least in part in special properties of the grammar construction tools available to the language learner rather than simply in a fixed set of grammatical rules hard wired into the brains of speakers. Copyright © 2015 Elsevier B.V. All rights reserved.

Marginal bone and soft tissue behavior following platform switching abutment connection/disconnection--a dog model study.

PubMed

Alves, Célia C; Muñoz, Fernando; Cantalapiedra, António; Ramos, Isabel; Neves, Manuel; Blanco, Juan

2015-09-01

The effect on the marginal peri-implant tissues following repeated platform switching abutment removal and subsequent reconnection was studied. Six adult female Beagle dogs were selected, and Pm3 and Pm4 teeth, both left and right sides, were extracted and the sites healed for 3 months. At this time, 24 bone level (BL) (Straumann, Basel, Switzerland) Ø 3.3/8 mm implants were placed, 2 in each side on Pm3 and Pm4 regions. In one side (control group), 12 bone level conical Ø 3.6 mm healing abutments and, on the other side (test group), 12 Narrow CrossFit (NC) multibase abutments (Straumann) , Basel, Switzerland) were connected at time of implant surgery. On test group, all prosthetic procedures were carried out direct to multibase abutment without disconnecting it, where in the control group, the multibase abutment was connected/disconnected five times (at 6/8/10/12/14 weeks) during prosthetic procedures. Twelve fixed metal bridges were delivered 14 weeks after implant placement. A cleaning/control appointment was scheduled 6 months after implant placement. The animals were sacrificed at 9 months of the study. Clinical parameters and peri-apical x-rays were registered in every visit. Histomorphometric analysis was carried out for the 24 implants. The distance from multibase abutment shoulder to the first bone implant contact (S-BIC) was defined as the primary histomorphometric parameter. Wilcoxon comparison paired test (n = 6) found no statistically significant differences (buccal P = 0.917; Lingual P = 0.463) between test and control groups both lingually and buccally for S-BIC distance. Only Pm3 buccal aBE-BC (distance from the apical end of the barrier epithelium to the first bone implant contact) (P = 0.046) parameter presented statistically significant differences between test and control groups. Control group presented 0.57 mm more recession than test group, being this difference statistically significant between the two groups (P < 0.001). It can be conclude, within the limits of this animal study, that the connection/disconnection of platform switching abutments during prosthetic phase of implant treatment does not induce bone marginal absorption. Furthermore, it may present a negative influence in the buccal connective tissue attachment that becomes shorter anyway preventing marginal hard tissue resorption, especially in thin biotypes. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Reflex limb dilatation following norepinephrine and angiotensin II in conscious dogs

NASA Technical Reports Server (NTRS)

Vatner, S. F.; Mcritchie, R. J.

1976-01-01

The extent to which norepinephrine (NE) and angiotensin II (AN) constrict the mesenteric, renal, and iliac beds in conscious dogs is evaluated with a view to elicit opposing reflex actions tempering the vasoconstriction in the limb of the animals tested. The afferent and efferent mechanisms mediating this reflex are analyzed. It is shown that intravenous NE and AN cause striking reflex iliac dilatation in the limb of the conscious dog. The afferent arc of this reflex involves both arterial baroreceptor and vagal path-ways, whereas the efferent mechanism involves an interaction of alpha-adrenergic and histaminergic receptors.

Flexion Reflex Can Interrupt and Reset the Swimming Rhythm.

PubMed

Elson, Matthew S; Berkowitz, Ari

2016-03-02

The spinal cord can generate the hip flexor nerve activity underlying leg withdrawal (flexion reflex) and the rhythmic, alternating hip flexor and extensor activities underlying locomotion and scratching, even in the absence of brain inputs and movement-related sensory feedback. It has been hypothesized that a common set of spinal interneurons mediates flexion reflex and the flexion components of locomotion and scratching. Leg cutaneous stimuli that evoke flexion reflex can alter the timing of (i.e., reset) cat walking and turtle scratching rhythms; in addition, reflex responses to leg cutaneous stimuli can be modified during cat and human walking and turtle scratching. Both of these effects depend on the phase (flexion or extension) of the rhythm in which the stimuli occur. However, similar interactions between leg flexion reflex and swimming have not been reported. We show here that a tap to the foot interrupted and reset the rhythm of forward swimming in spinal, immobilized turtles if the tap occurred during the swim hip extensor phase. In addition, the hip flexor nerve response to an electrical foot stimulus was reduced or eliminated during the swim hip extensor phase. These two phase-dependent effects of flexion reflex on the swim rhythm and vice versa together demonstrate that the flexion reflex spinal circuit shares key components with or has strong interactions with the swimming spinal network, as has been shown previously for cat walking and turtle scratching. Therefore, leg flexion reflex circuits likely share key spinal interneurons with locomotion and scratching networks across limbed vertebrates generally. The spinal cord can generate leg withdrawal (flexion reflex), locomotion, and scratching in limbed vertebrates. It has been hypothesized that there is a common set of spinal cord neurons that produce hip flexion during flexion reflex, locomotion, and scratching based on evidence from studies of cat and human walking and turtle scratching. We show here that flexion reflex and swimming also share key spinal cord components based on evidence from turtles. Foot stimulation can reset the timing of the swimming rhythm and the response to each foot stimulation can itself be altered by the swim rhythm. Collectively, these studies suggest that spinal cord neuronal networks underlying flexion reflex, multiple forms of locomotion, and scratching share key components. Copyright © 2016 the authors 0270-6474/16/362819-08$15.00/0.

The Moro reaction: More than a reflex, a ritualized behavior of nonverbal communication.

PubMed

Rousseau, Pierre V; Matton, Florence; Lecuyer, Renaud; Lahaye, Willy

2017-02-01

To propose a phylogenetic significance to the Moro reflex which remains unexplained since its publication in 1918 because both hands are free at the end of the gesture. Among the 75 videos of healthy term newborns we have filmed in a research project on antenatal education to parenthood, we describe a sequence that clearly showed the successive movements of the Moro reflex and we report the occurrence of this reflex in the videos that were recorded from Time 0 of birth defined as the moment that lies between the birth of the thorax and the pelvis of the infant. The selected sequence showed the following succession of the newborn's actions: quick extension-adduction of both arms, the orientation of the body, head and eyes towards a human person, and full extension-abduction of both arms with spreading of the fingers, crying and a distressed face. There were 13 Moro reflexes between 2 and 14s from Time 0 of birth. We found a significant association between the occurrence of the Moro reflex and the placement of the newborn at birth in supine position on the mother's abdomen (p=0.002). The quick extension-adduction of both arms which started the sequence may be considered as a startle reflex controlled by the neural fear system and the arm extension-adduction which followed as a Moro reflex. The characteristics of all Moro reflexes were those of ritualization: amplitude, duration, stereotype of the gestures. This evolutionary process turns a physiological behavior, grasping in this case, to a non-verbal communicative behavior whose meaning is a request to be picked up in the arms. The gestures associated with the Moro reflex: crying and orientation of the body, head, and eyes towards a human person, are gestures of intention to communicate which support our hypothesis. The neural mechanism of the Moro reaction probably involves both the fear and the separation-distress systems. This paper proposes for the first time a phylogenetic significance to the Moro reflex: a ritualized behavior of nonverbal communication. Professionals should avoid stimulating the newborns' fear system by unnecessarily triggering Moro reflexes. Antenatal education should teach parents to respond to the Moro reflexes of their newborn infant by picking her up in their arms with mother talk. Copyright © 2017 Elsevier Inc. All rights reserved.

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

ERIC Educational Resources Information Center

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…

Indicators used in livestock to assess unconsciousness after stunning: a review.

PubMed

Verhoeven, M T W; Gerritzen, M A; Hellebrekers, L J; Kemp, B

2015-02-01

Assessing unconsciousness is important to safeguard animal welfare shortly after stunning at the slaughter plant. Indicators that can be visually evaluated are most often used when assessing unconsciousness, as they can be easily applied in slaughter plants. These indicators include reflexes originating from the brain stem (e.g. eye reflexes) or from the spinal cord (e.g. pedal reflex) and behavioural indicators such as loss of posture, vocalisations and rhythmic breathing. When physically stunning an animal, for example, captive bolt, most important indicators looked at are posture, righting reflex, rhythmic breathing and the corneal or palpebral reflex that should all be absent if the animal is unconscious. Spinal reflexes are difficult as a measure of unconsciousness with this type of stunning, as they may occur more vigorous. For stunning methods that do not physically destroy the brain, for example, electrical and gas stunning, most important indicators looked at are posture, righting reflex, natural blinking response, rhythmic breathing, vocalisations and focused eye movement that should all be absent if the animal is unconscious. Brain stem reflexes such as the cornea reflex are difficult as measures of unconsciousness in electrically stunned animals, as they may reflect residual brain stem activity and not necessarily consciousness. Under commercial conditions, none of the indicators mentioned above should be used as a single indicator to determine unconsciousness after stunning. Multiple indicators should be used to determine unconsciousness and sufficient time should be left for the animal to die following exsanguination before starting invasive dressing procedures such as scalding or skinning. The recording and subsequent assessment of brain activity, as presented in an electroencephalogram (EEG), is considered the most objective way to assess unconsciousness compared with reflexes and behavioural indicators, but is only applied in experimental set-ups. Studies performed in an experimental set-up have often looked at either the EEG or reflexes and behavioural indicators and there is a scarcity of studies that correlate these different readout parameters. It is recommended to study these correlations in more detail to investigate the validity of reflexes and behavioural indicators and to accurately determine the point in time at which the animal loses consciousness.

Parallel facilitatory reflex pathways from the foot and hip to flexors and extensors in the injured human spinal cord

PubMed Central

Knikou, Maria; Kay, Elizabeth; Schmit, Brian D.

2007-01-01

Spinal integration of sensory signals associated with hip position, muscle loading, and cutaneous sensation of the foot contributes to movement regulation. The exact interactive effects of these sensory signals under controlled dynamic conditions are unknown. The purpose of the present study was to establish the effects of combined plantar cutaneous afferent excitation and hip movement on the Hoffmann (H) and flexion reflexes in people with a spinal cord injury (SCI). The flexion and H-reflexes were elicited through stimulation of the right sural (at non-nociceptive levels) and posterior tibial nerves respectively. Reflex responses were recorded from the ipsilateral tibialis anterior (TA) (flexion reflex) and soleus (H-reflex) muscles. The plantar cutaneous afferents were stimulated at three times the perceptual threshold (200 Hz, 24-ms pulse train) at conditioning–test intervals that ranged from 3 to 90 ms. Sinusoidal movements were imposed to the right hip joint at 0.2 Hz with subjects supine. Control and conditioned reflexes were recorded as the hip moved in flexion and extension. Leg muscle activity and sagittal-plane joint torques were recorded. We found that excitation of plantar cutaneous afferents facilitated the soleus H-reflex and the long latency flexion reflex during hip extension. In contrast, the short latency flexion reflex was depressed by plantar cutaneous stimulation during hip flexion. Oscillatory joint forces were present during the transition phase of the hip movement from flexion to extension when stimuli were delivered during hip flexion. Hip-mediated input interacts with feedback from the foot sole to facilitate extensor and flexor reflex activity during the extension phase of movement. The interactive effects of these sensory signals may be a feature of impaired gait, but when they are appropriately excited, they may contribute to locomotion recovery in these patients. PMID:17543951

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

PubMed Central

2010-01-01

Background 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 ~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. Methods 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. Results 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. Conclusion 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 findings also apply to long-term adaption to the exoskeleton. PMID:20659331

Convergence of flexor reflex and corticospinal inputs on tibialis anterior network in humans.

PubMed

Mackey, Ann S; Uttaro, Denise; McDonough, Maureen P; Krivis, Lisa I; Knikou, Maria

2016-01-01

Integration between descending and ascending inputs at supraspinal and spinal levels is a key characteristic of neural control of movement. In this study, we characterized convergence of the flexor reflex and corticospinal inputs on the tibialis anterior (TA) network in healthy human subjects. Specifically, we characterized the modulation profiles of the spinal TA flexor reflex following subthreshold and suprathreshold transcranial magnetic stimulation (TMS). We also characterized the modulation profiles of the TA motor evoked potentials (MEPs) following medial arch foot stimulation at sensory and above reflex threshold. TA flexor reflexes were evoked following stimulation of the medial arch of the foot with a 30 ms pulse train at innocuous intensities. TA MEPs were evoked following TMS of the leg motor cortex area. TMS at 0.7 and at 1.2 MEP resting threshold increased the TA flexor reflex when TMS was delivered 40-100 ms after foot stimulation, and decreased the TA flexor reflex when TMS was delivered 25-110 ms before foot stimulation. Foot stimulation at sensory and above flexor reflex threshold induced a similar time-dependent modulation in resting TA MEPs, that were facilitated when foot stimulation was delivered 40-100 ms before TMS. The flexor reflex and MEPs recorded from the medial hamstring muscle were modulated in a similar manner to that observed for the TA flexor reflex and MEP. Cutaneomuscular afferents from the distal foot can increase the output of the leg motor cortex area. Descending motor volleys that directly or indirectly depolarize flexor motoneurons increase the output of the spinal FRA interneuronal network. The parallel facilitation of flexor MEPs and flexor reflexes is likely cortical in origin. Afferent mediated facilitation of corticospinal excitability can be utilized to strengthen motor cortex output in neurological disorders. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Rate of EGFR mutation testing for patients with nonsquamous non-small-cell lung cancer with implementation of reflex testing by pathologists

PubMed Central

Cheema, P.K.; Raphael, S.; El-Maraghi, R.; Li, J.; McClure, R.; Zibdawi, L.; Chan, A.; Victor, J.C.; Dolley, A.; Dziarmaga, A.

2017-01-01

Background Testing for mutation of the EGFR (epidermal growth factor receptor) gene is a standard of care for patients with advanced nonsquamous non-small-cell lung cancer (nsclc). To improve timely access to EGFR results, a few centres implemented reflex testing, defined as a request for EGFR testing by the pathologist at the time of a nonsquamous nsclc diagnosis. We evaluated the impact of reflex testing on EGFR testing rates. Methods A retrospective observational review of the Web-based AstraZeneca Canada EGFR Database from 1 April 2010 to 31 March 2014 found centres within Ontario that had requested EGFR testing through the database and that had implemented reflex testing (with at least 2 years’ worth of data, including the pre- and post-implementation period). Results The 7 included centres had requested EGFR tests for 2214 patients. The proportion of pathologists requesting EGFR tests increased after implementation of reflex testing (53% vs. 4%); conversely, the proportion of medical oncologists requesting tests decreased (46% vs. 95%, p < 0.001). After implementation of reflex testing, the mean number of patients having EGFR testing per centre per month increased significantly [12.6 vs. 4.9 (range: 4.5–14.9), p < 0.001]. Before reflex testing, EGFR testing rates showed a significant monthly increase over time (1.37 more tests per month; 95% confidence interval: 1.19 to 1.55 tests; p < 0.001). That trend could not account for the observed increase with reflex testing, because an immediate increase in EGFR test requests was observed with the introduction of reflex testing (p = 0.003), and the overall trend was sustained throughout the post–reflex testing period (p < 0.001). Conclusions Reflex EGFR testing for patients with nonsquamous nsclc was successfully implemented at multiple centres and was associated with an increase in EGFR testing. PMID:28270720

Minimally invasive anterior pelvic internal fixation: An anatomic study comparing Pelvic Bridge to INFIX.

PubMed

Reichel, Lee M; MacCormick, Lauren M; Dugarte, Anthony J; Rizkala, Amir R; Graves, Sara C; Cole, Peter A

2018-02-01

Anterior external fixation for pelvic ring fractures has shown to effectively improve stability and reduce mortality. However, these fixators can be associated with substantial morbidity such as pin tract infection, premature loss of fixation, and decreased quality of life in patients. Recently, two new methods of subcutaneous anterior pelvic internal fixation have been developed; the INFIX and the Pelvic Bridge. These methods have the purported advantages of lower wound complications, less surgical site pain, and improved quality of life. We sought to investigate the measured distances to critical anatomic structures, as well as the qualitative and topographic differences notable during implantation of both devices in the same cadaveric specimen. The Pelvic Bridge and INFIX were implanted in eleven fresh cadavers. Distances were then measured to: the superficial inguinal ring, round ligament, spermatic cord, lateral femoral cutaneous nerve (LFCN), femoral nerve, femoral artery, and femoral vein. Observations regarding implantation and topography were also recorded. The INFIX had greater measured distances from all structures except for the LFCN, in which its proximity placed this structure at risk. Neither device appears to put other critical structures at risk in the supine position. Significant implantation and topographic differences exist between the devices. The INFIX application lacked "safety margins" concerning the LFCN in 10/11 (90.9%) specimens, while Pelvic Bridge placement lacked "safety margins" with regard to the right superficial ring (1/11, 9%) and the right spermatic cord (1/11, 9%). Both the Pelvic Bridge and INFIX lie at safe distances from most critical pelvic structures in the supine position, though INFIX application places the LFCN at risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modulation of spinal inhibitory reflexes depends on the frequency of transcutaneous electrical nerve stimulation in spastic stroke survivors.

PubMed

Koyama, Soichiro; Tanabe, Shigeo; Takeda, Kazuya; Sakurai, Hiroaki; Kanada, Yoshikiyo

2016-03-01

Neurophysiological studies in healthy subjects suggest that increased spinal inhibitory reflexes from the tibialis anterior (TA) muscle to the soleus (SOL) muscle might contribute to decreased spasticity. While 50 Hz is an effective frequency for transcutaneous electrical nerve stimulation (TENS) in healthy subjects, in stroke survivors, the effects of TENS on spinal reflex circuits and its appropriate frequency are not well known. We examined the effects of different frequencies of TENS on spinal inhibitory reflexes from the TA to SOL muscle in stroke survivors. Twenty chronic stroke survivors with ankle plantar flexor spasticity received 50-, 100-, or 200-Hz TENS over the deep peroneal nerve (DPN) of the affected lower limb for 30 min. Before and immediately after TENS, reciprocal Ia inhibition (RI) and presynaptic inhibition of the SOL alpha motor neuron (D1 inhibition) were assessed by adjusting the unconditioned H-reflex amplitude. Furthermore, during TENS, the time courses of spinal excitability and spinal inhibitory reflexes were assessed via the H-reflex, RI, and D1 inhibition. None of the TENS protocols affected mean RI, whereas D1 inhibition improved significantly following 200-Hz TENS. In a time-series comparison during TENS, repeated stimulation did not produce significant changes in the H-reflex, RI, or D1 inhibition regardless of frequency. These results suggest that the frequency-dependent effect of TENS on spinal reflexes only becomes apparent when RI and D1 inhibition are measured by adjusting the amplitude of the unconditioned H-reflex. However, 200-Hz TENS led to plasticity of synaptic transmission from the antagonist to spastic muscles in stroke survivors.

Neuromuscular function during drop jumps in young and elderly males.

PubMed

Piirainen, Jarmo M; Linnamo, Vesa; Sippola, Niina; Avela, Janne

2012-12-01

The Hoffman reflex (H-reflex), indicating alpha-motoneuron pool activity, has been shown to be task - and in resting conditions - age dependent. How aging affects H-reflex activity during explosive movements is not clear at present. The purpose of this study was to examine the effects of aging on H-reflexes during drop jumps, and its possible role in drop jump performance. Ten young (26.8 ± 2.7 years) and twenty elderly (64.2 ± 2.7 years) subjects participated in the study. Maximal drop jump performance and soleus H-reflex response (H/M jump) 20 ms after ground contact were measured in a sledge ergometer. Maximal H-reflex, maximal M-wave, Hmax/Mmax-ratio and H-reflex excitability curves were measured during standing rest. Although in young the H-reflex response (Hmax/Mmax) was 6.5% higher during relaxed standing and 19.7% higher during drop jumps (H jump/M jump) than in the elderly group, these differences were not statistically significant. In drop jumps, the elderly subjects had lower jumping height (30.4%, p < 0.001), longer braking time (32.4%, p < 0.01), lower push-off force (18.0%, p < 0.05) and longer push-off time (31.0% p < 0.01). H jump/M jump correlated with the average push-off force (r = 0.833, p < 0.05) and with push-off time (r = -0.857, p < 0.01) in young but not in the elderly. Correlations between H-reflex response and jumping parameters in young may indicate different jumping and activation strategies in drop jumps. However, it does not fully explain age related differences in jumping performance, since age related differences in H-reflex activity were non-significant. Copyright © 2012 Elsevier Ltd. All rights reserved.

Detection and identification of oral anaerobes in intraoperative bronchial fluids of patients with pulmonary carcinoma.

PubMed

Hasegawa, Ayako; Sato, Takuichi; Hoshikawa, Yasushi; Ishida, Naoko; Tanda, Naoko; Kawamura, Yoshiaki; Kondo, Takashi; Takahashi, Nobuhiro

2014-07-01

Postoperative pneumonia may occur when upper respiratory tract protective reflexes such as cough and/or swallowing reflexes are impaired; thus, silent aspiration of oral bacteria may be a causative factor in postoperative pneumonia. This study aimed to quantify and identify bacteria in intraoperative bronchial fluids and to evaluate the relationship between impairment of cough/swallowing reflexes and silent aspiration of oral bacteria in elderly patients. After obtaining informed consent, cough and swallowing reflexes were assessed using an ultrasonic nebulizer and a nasal catheter, respectively. Using a micro-sampling probe, intraoperative bronchial fluids were collected from nine subjects with pulmonary carcinoma and cultured anaerobically on blood agar plates. After 7 days, CFUs were counted and isolated bacteria were identified by 16S rRNA gene sequencing. Four subjects (aged 71.0 ± 8.4 years) had impaired swallowing reflexes with normal cough reflexes, whereas five subjects (73.6 ± 6.5 years) had normal cough and swallowing reflexes. The bacterial counts (mean CFU ± SD) tended to be higher in intraoperative bronchial fluids of subjects with impaired swallowing reflexes ([5.1 ± 7.7] × 10(5)) than in those of subjects with normal reflexes ([1.2 ± 1.9] × 10(5)); however, this difference was not statistically significant. Predominant isolates from intraoperative bronchial fluids were Streptococcus (41.8%), Veillonella (11.4%), Gemella (8.9%), Porphyromonas (7.6%), Olsenella (6.3%) and Eikenella (6.3%). These findings indicate that intraoperative bronchial fluids contain bacteria, probably derived from the oral microbiota, and suggest that silent aspiration of oral bacteria occurs in elderly patients irrespective of impairment of swallowing reflex. © 2014 The Societies and Wiley Publishing Asia Pty Ltd.

Hip proprioceptors preferentially modulate reflexes of the leg in human spinal cord injury

PubMed Central

Onushko, Tanya; Hyngstrom, Allison

2013-01-01

Stretch-sensitive afferent feedback from hip muscles has been shown to trigger long-lasting, multijoint reflex responses in people with chronic spinal cord injury (SCI). These reflexes could have important implications for control of leg movements during functional activities, such as walking. Because the control of leg movement relies on reflex regulation at all joints of the limb, we sought to determine whether stretch of hip muscles modulates reflex activity at the knee and ankle and, conversely, whether knee and ankle stretch afferents affect hip-triggered reflexes. A custom-built servomotor apparatus was used to stretch the hip muscles in nine chronic SCI subjects by oscillating the legs about the hip joint bilaterally from 10° of extension to 40° flexion. To test whether stretch-related feedback from the knee or ankle would be affected by hip movement, patellar tendon percussions and Achilles tendon vibration were delivered when the hip was either extending or flexing. Surface electromyograms (EMGs) and joint torques were recorded from both legs. Patellar tendon percussions and Achilles tendon vibration both elicited reflex responses local to the knee or ankle, respectively, and did not influence reflex responses observed at the hip. Rather, the movement direction of the hip modulated the reflex responses local to the joint. The patellar tendon reflex amplitude was larger when the perturbation was delivered during hip extension compared with hip flexion. The response to Achilles vibration was modulated by hip movement, with an increased tonic component during hip flexion compared with extension. These results demonstrate that hip-mediated sensory signals modulate activity in distal muscles of the leg and appear to play a unique role in modulation of spastic muscle activity throughout the leg in SCI. PMID:23615544

Are H-reflex and M-wave recruitment curve parameters related to aerobic capacity?

PubMed

Piscione, Julien; Grosset, Jean-François; Gamet, Didier; Pérot, Chantal

2012-10-01

Soleus Hoffmann reflex (H-reflex) amplitude is affected by a training period and type and level of training are also well known to modify aerobic capacities. Previously, paired changes in H-reflex and aerobic capacity have been evidenced after endurance training. The aim of this study was to investigate possible links between H- and M-recruitment curve parameters and aerobic capacity collected on a cohort of subjects (56 young men) that were not involved in regular physical training. Maximal H-reflex normalized with respect to maximal M-wave (H(max)/M(max)) was measured as well as other parameters of the H- or M-recruitment curves that provide information about the reflex or direct excitability of the motoneuron pool, such as thresholds of stimulus intensity to obtain H or M response (H(th) and M(th)), the ascending slope of H-reflex, or M-wave recruitment curves (H(slp) and M(slp)) and their ratio (H(slp)/M(slp)). Aerobic capacity, i.e., maximal oxygen consumption and maximal aerobic power (MAP) were, respectively, estimated from a running field test and from an incremental test on a cycle ergometer. Maximal oxygen consumption was only correlated with M(slp), an indicator of muscle fiber heterogeneity (p < 0.05), whereas MAP was not correlated with any of the tested parameters (p > 0.05). Although higher H-reflex are often described for subjects with a high aerobic capacity because of endurance training, at a basic level (i.e., without training period context) no correlation was observed between maximal H-reflex and aerobic capacity. Thus, none of the H-reflex or M-wave recruitment curve parameters, except M(slp), was related to the aerobic capacity of young, untrained male subjects.

Locomotor impact of beneficial or nonbeneficial H-reflex conditioning after spinal cord injury

PubMed Central

Chen, Yi; Chen, Lu; Liu, Rongliang; Wang, Yu; Wolpaw, Jonathan R.

2013-01-01

When new motor learning changes neurons and synapses in the spinal cord, it may affect previously learned behaviors that depend on the same spinal neurons and synapses. To explore these effects, we used operant conditioning to strengthen or weaken the right soleus H-reflex pathway in rats in which a right spinal cord contusion had impaired locomotion. When up-conditioning increased the H-reflex, locomotion improved. Steps became longer, and step-cycle asymmetry (i.e., limping) disappeared. In contrast, when down-conditioning decreased the H-reflex, locomotion did not worsen. Steps did not become shorter, and asymmetry did not increase. Electromyographic and kinematic analyses explained how H-reflex increase improved locomotion and why H-reflex decrease did not further impair it. Although the impact of up-conditioning or down-conditioning on the H-reflex pathway was still present during locomotion, only up-conditioning affected the soleus locomotor burst. Additionally, compensatory plasticity apparently prevented the weaker H-reflex pathway caused by down-conditioning from weakening the locomotor burst and further impairing locomotion. The results support the hypothesis that the state of the spinal cord is a “negotiated equilibrium” that serves all the behaviors that depend on it. When new learning changes the spinal cord, old behaviors undergo concurrent relearning that preserves or improves their key features. Thus, if an old behavior has been impaired by trauma or disease, spinal reflex conditioning, by changing a specific pathway and triggering a new negotiation, may enable recovery beyond that achieved simply by practicing the old behavior. Spinal reflex conditioning protocols might complement other neurorehabilitation methods and enhance recovery. PMID:24371288

Vastus Medialis Hoffmann Reflex Excitability Is Associated With Pain Level, Self-Reported Function, and Chronicity in Women With Patellofemoral Pain.

PubMed

de Oliveira Silva, Danilo; Magalhães, Fernando Henrique; Faria, Nathálie Clara; Ferrari, Deisi; Pazzinatto, Marcella Ferraz; Pappas, Evangelos; de Azevedo, Fábio Mícolis

2017-01-01

To determine the association between the amplitude of vastus medialis (VM) Hoffmann reflex (H-reflex) and pain level, self-reported physical function, and chronicity of pain in women with patellofemoral pain (PFP). Cross-sectional study. Laboratory of biomechanics and motor control. Women diagnosed with PFP (N=15) aged 18 to 35 years. Not applicable. Data on worst pain level during the previous month, self-reported physical function, and symptom duration (chronicity) were collected from the participants. Maximum evoked responses were obtained by electrical stimulation applied to the femoral nerve and peak-to-peak amplitudes of normalized maximal H-reflexes (maximal Hoffmann reflex/maximal motor wave ratios) of the VM were calculated. A Pearson product-moment correlation matrix (r) was used to explore the relations between the amplitude of VM H-reflex and worst pain during the previous month, self-reported function, and chronicity of pain. Strong negative correlations were found between the amplitude of VM H-reflex and worst pain in the previous month (r=-.71; P=.003) and chronicity (r=-.74; P=.001). A strong positive correlation was found between the amplitude of VM H-reflex and self-reported physical function (r=.62; P=.012). The strong and significant relations reported in this study suggest that women with PFP showing greater VM H-reflex excitability tend to have lower pain, better physical function, and more recent symptoms. Therefore, rehabilitation strategies designed to increase the excitability of the monosynaptic stretch reflex should be considered in the treatment of women with PFP if their effectiveness is demonstrated in future studies. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

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

PubMed

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.

Circumferential resection margin positivity after preoperative chemoradiotherapy based on magnetic resonance imaging for locally advanced rectal cancer: implication of boost radiotherapy to the involved mesorectal fascia.

PubMed

Kim, Kyung Hwan; Park, Min Jung; Lim, Joon Seok; Kim, Nam Kyu; Min, Byung Soh; Ahn, Joong Bae; Kim, Tae Il; Kim, Ho Geun; Koom, Woong Sub

2016-04-01

To identify patients who are at a higher risk of pathologic circumferential resection margin involvement using preoperative magnetic resonance imaging. Between October 2008 and November 2012, 165 patients with locally advanced rectal cancer (cT4 or cT3 with <2 mm distance from tumour to mesorectal fascia) who received preoperative chemoradiotherapy were analysed. The morphologic patterns on post-chemoradiotherapy magnetic resonance imaging were categorized into five patterns from Pattern A (most-likely negative pathologic circumferential resection margin) to Pattern E (most-likely positive pathologic circumferential resection margin). In addition, the location of mesorectal fascia involvement was classified as lateral, posterior and anterior. The diagnostic accuracy of the morphologic criteria was calculated using receiver operating characteristic curve analysis. Pathologic circumferential resection margin involvement was identified in 17 patients (10.3%). The diagnostic accuracy of predicting pathologic circumferential resection margin involvement was 0.73 using the five-scale magnetic resonance imaging pattern. The sensitivity, specificity, positive predictive value and negative predictive value for predicting pathologic circumferential resection margin involvement were 76.5, 65.5, 20.3 and 96.0%, respectively, when cut-off was set between Patterns C and D. On multivariate logistic regression, the magnetic resonance imaging patterns D and E (P= 0.005) and posterior or lateral mesorectal fascia involvement (P= 0.017) were independently associated with increased probability of pathologic circumferential resection margin involvement. The rate of pathologic circumferential resection margin involvement was 30.0% when the patient had Pattern D or E with posterior or lateral mesorectal fascia involvement. Patients who are at a higher risk of pathologic circumferential resection margin involvement can be identified using preoperative magnetic resonance imaging although the predictability is moderate. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

WE-G-BRD-08: Motion Analysis for Rectal Cancer: Implications for Adaptive Radiotherapy On the MR-Linac

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

Kleijnen, J; Asselen, B van; Burbach, M

2015-06-15

Purpose: Purpose of this study is to find the optimal trade-off between adaptation interval and margin reduction and to define the implications of motion for rectal cancer boost radiotherapy on a MR-linac. Methods: Daily MRI scans were acquired of 16 patients, diagnosed with rectal cancer, prior to each radiotherapy fraction in one week (N=76). Each scan session consisted of T2-weighted and three 2D sagittal cine-MRI, at begin (t=0 min), middle (t=9:30 min) and end (t=18:00 min) of scan session, for 1 minute at 2 Hz temporal resolution. Tumor and clinical target volume (CTV) were delineated on each T2-weighted scan andmore » transferred to each cine-MRI. The start frame of the begin scan was used as reference and registered to frames at time-points 15, 30 and 60 seconds, 9:30 and 18:00 minutes and 1, 2, 3 and 4 days later. Per time-point, motion of delineated voxels was evaluated using the deformation vector fields of the registrations and the 95th percentile distance (dist95%) was calculated as measure of motion. Per time-point, the distance that includes 90% of all cases was taken as estimate of required planning target volume (PTV)-margin. Results: Highest motion reduction is observed going from 9:30 minutes to 60 seconds. We observe a reduction in margin estimates from 10.6 to 2.7 mm and 16.1 to 4.6 mm for tumor and CTV, respectively, when adapting every 60 seconds compared to not adapting treatment. A 75% and 71% reduction, respectively. Further reduction in adaptation time-interval yields only marginal motion reduction. For adaptation intervals longer than 18:00 minutes only small motion reductions are observed. Conclusion: The optimal adaptation interval for adaptive rectal cancer (boost) treatments on a MR-linac is 60 seconds. This results in substantial smaller PTV-margin estimates. Adaptation intervals of 18:00 minutes and higher, show little improvement in motion reduction.« less

The forces generated at the human elbow joint in response to imposed sinusoidal movements of the forearm

PubMed Central

Joyce, G. C.; Rack, Peter M. H.; Ross, H. F.

1974-01-01

1. The mechanical resistance of the human forearm has been measured during imposed sinusoidal flexion-extension movements of the elbow joint. 2. The force required to move the limb can be divided into components required to move the mass, and components required to overcome the resistance offered by elastic and frictional properties of the muscles and other soft tissues. 3. When during a vigorous flexing effort the limb was subjected to a small amplitude sinusoidal movement each extension was followed by a considerable reflex contraction of the flexor muscles. At low frequencies of movement this reflex provided an added resistance to extension, but at 8-12 Hz the delay in the reflex pathway was such that the reflex response to extension occurred after the extension phase of the movement was over and during the subsequent flexion movement. The reflex activity then assisted the movement whereas at other frequencies it impeded it. 4. The reflex response to movement increased as the subject exerted a greater flexing force. 5. Small movements generated a relatively larger reflex response than big ones. 6. Even with large amplitudes of movement when the reflex activity was relatively small, the limb resisted extension with a high level of stiffness; this was comparable with the short range stiffness of muscles in experimental animals. 7. The fact that at some frequencies the reflex response assisted the movement implies that with appropriate loading the limb could undergo a self-sustaining oscillation at those frequencies. PMID:4420490

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

PubMed

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.

On reflexivity and the conduct of the self in everyday life: reflections on Bourdieu and Archer.

PubMed

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.

Analysis of factors related to vagally mediated reflex bradycardia during gastrectomy.

PubMed

Kim, Duk-Kyung; Ahn, Hyun Joo; Lee, Seung Won; Choi, Ji Won

2015-12-01

Because vagally mediated reflex bradycardia occurs frequently during gastrectomy and is potentially harmful, we compared the incidence of clinically significant reflex bradycardia between patients undergoing laparoscopic gastrectomy (LG) and open gastrectomy (OG) and examined whether the type of surgery (OG vs. LG) was an independent risk factor for clinically significant reflex bradycardia. This prospective observational study evaluated 358 adult patients (age 18-70 years) who were undergoing elective OG or LG for gastric cancer resection. Symptomatic reflex bradycardia was defined as a sudden decrease in heart rate to <50 beats per minute (bpm), or to 50-59 bpm with a systolic blood pressure <70 mmHg, associated with a specific surgical maneuver. If bradycardia or hypotension developed, atropine or ephedrine was administered, in accordance with a predefined treatment protocol. The overall incidence of symptomatic reflex bradycardia was 24.6% (88/358). Univariate analysis revealed the incidence of symptomatic reflex bradycardia in the LG group was significantly lower than that in the OG group [13.0% (13/100) vs. 29.1% (75/258), p = 0.002]. Multivariate logistic regression analysis revealed that the type of surgery (OG vs. LG), advanced age, preoperative bradycardia, type of muscle relaxant (vecuronium vs. rocuronium), no use of intravenous remifentanil, and low core temperature, were independent risk factors for symptomatic reflex bradycardia (odds ratio 3.184; 95% confidence interval 1.490-6.800; p = 0.003). The LG approach was associated with a reduced risk of clinically significant reflex bradycardia compared with the OG approach.

Realistic respiratory motion margins for external beam partial breast irradiation

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

Conroy, Leigh; Quirk, Sarah; Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4

Purpose: Respiratory margins for partial breast irradiation (PBI) have been largely based on geometric observations, which may overestimate the margin required for dosimetric coverage. In this study, dosimetric population-based respiratory margins and margin formulas for external beam partial breast irradiation are determined. Methods: Volunteer respiratory data and anterior–posterior (AP) dose profiles from clinical treatment plans of 28 3D conformal radiotherapy (3DCRT) PBI patient plans were used to determine population-based respiratory margins. The peak-to-peak amplitudes (A) of realistic respiratory motion data from healthy volunteers were scaled from A = 1 to 10 mm to create respiratory motion probability density functions. Dosemore » profiles were convolved with the respiratory probability density functions to produce blurred dose profiles accounting for respiratory motion. The required margins were found by measuring the distance between the simulated treatment and original dose profiles at the 95% isodose level. Results: The symmetric dosimetric respiratory margins to cover 90%, 95%, and 100% of the simulated treatment population were 1.5, 2, and 4 mm, respectively. With patient set up at end exhale, the required margins were larger in the anterior direction than the posterior. For respiratory amplitudes less than 5 mm, the population-based margins can be expressed as a fraction of the extent of respiratory motion. The derived formulas in the anterior/posterior directions for 90%, 95%, and 100% simulated population coverage were 0.45A/0.25A, 0.50A/0.30A, and 0.70A/0.40A. The differences in formulas for different population coverage criteria demonstrate that respiratory trace shape and baseline drift characteristics affect individual respiratory margins even for the same average peak-to-peak amplitude. Conclusions: A methodology for determining population-based respiratory margins using real respiratory motion patterns and dose profiles in the AP direction was described. It was found that the currently used respiratory margin of 5 mm in partial breast irradiation may be overly conservative for many 3DCRT PBI patients. Amplitude alone was found to be insufficient to determine patient-specific margins: individual respiratory trace shape and baseline drift both contributed to the dosimetric target coverage. With respiratory coaching, individualized respiratory margins smaller than the full extent of motion could reduce planning target volumes while ensuring adequate coverage under respiratory motion.« less

Teaching about Prejudice with a Bogardus Social Distance Scale Activity: Replication and Extension

ERIC Educational Resources Information Center

Maurer, Trent W.; Keim, Cassidy

2018-01-01

This study presents a three-year replication and extension of Maurer's (2013) evaluation of a classroom activity to reduce prejudice and discrimination. Students in six sections of an introductory family science course were assigned to one of three conditions and one of two target marginalized groups for a 3x2 design. Results differed…

46 CFR 171.065 - Subdivision requirements- Type I.

Code of Federal Regulations, 2011 CFR

2011-10-01

... located above the inner bottom forward or aft of the machinery space in cubic feet. P=the volume of... volume of the machinery space and the volumes of any fuel tanks which are located above the inner bottom... and the total volume of passenger spaces above the margin line. (c) The distance A in Figure 171.065...

46 CFR 171.065 - Subdivision requirements- Type I.

Code of Federal Regulations, 2014 CFR

2014-10-01

... located above the inner bottom forward or aft of the machinery space in cubic feet. P=the volume of... volume of the machinery space and the volumes of any fuel tanks which are located above the inner bottom... and the total volume of passenger spaces above the margin line. (c) The distance A in Figure 171.065...

46 CFR 171.065 - Subdivision requirements- Type I.

Code of Federal Regulations, 2013 CFR

2013-10-01

... located above the inner bottom forward or aft of the machinery space in cubic feet. P=the volume of... volume of the machinery space and the volumes of any fuel tanks which are located above the inner bottom... and the total volume of passenger spaces above the margin line. (c) The distance A in Figure 171.065...

46 CFR 171.065 - Subdivision requirements- Type I.

Code of Federal Regulations, 2012 CFR

2012-10-01

... located above the inner bottom forward or aft of the machinery space in cubic feet. P=the volume of... volume of the machinery space and the volumes of any fuel tanks which are located above the inner bottom... and the total volume of passenger spaces above the margin line. (c) The distance A in Figure 171.065...

Course of the inferior vena cava on lateral films exposed in different positions.

PubMed

Lien, H H; Bakke, S J

1981-01-01

The distance from the posterior border of the inferior vena cava to the anterior vertebral margin was measured in 100 presumably normal patients in the supine position. Seventeen of these were also examined in the right and left lateral positions and the changes in course of the vena cava compared with the supine position.

Distance between Quantum States and Gauge-Gravity Duality.

PubMed

Miyaji, Masamichi; Numasawa, Tokiro; Shiba, Noburo; Takayanagi, Tadashi; Watanabe, Kento

2015-12-31

We study a quantum information metric (or fidelity susceptibility) in conformal field theories with respect to a small perturbation by a primary operator. We argue that its gravity dual is approximately given by a volume of maximal time slice in an anti-de Sitter spacetime when the perturbation is exactly marginal. We confirm our claim in several examples.

Two-dimensional analysis of palpebral opening in blepharoptosis: visual iris-pupil complex percentage by digital photography.

PubMed

Choi, Yeop; Eo, SuRak

2014-04-01

The vertical dimension of the palpebral fissure and the marginal reflex distance are conventionally used to assess the amount or degree of blepharoptosis, and levator function is assessed by measuring total upper lid excursion between the extremes of down-gaze and up-gaze. However, these are 1-dimensional measures obtained with a ruler, and the results obtained are dependent on examiner skill. Digital photographs were obtained of 692 patients before and after upper blepharoplasty. Visual iris-pupil complex percentage (VIP) was measured in the 1,305 eyes by digital calculation using Adobe Photoshop CS3 (Adobe Systems, Inc). Perioperative eye images in primary gaze were evaluated independently by 2 surgeons, 2 nurses, and a graphic designer, and after excluding 50 eyes which were nonconcordant and 29 eyes which revealed retracted upper lids, the remaining 1,305 eyes were classified into 4 major groups, that is, into excellent (n = 415), good (n = 435), subclinical (n = 270), and prominent ptosis (n = 185) groups. In addition, eyes were subdivided into 5 types according to the iris-pupil complex position within the palpebral fissure. Visual iris-pupil complex percentages were from 85% to 94% in the excellent, from 78% to 84% in the good, from 70% to 77% in the subclinical ptosis, and below 70% in the prominent ptosis group. Patients in the subclinical or prominent ptosis eye group required surgery for blepharoptosis. Iris-pupil complex relation to the palpebral opening was classified into 5 eye types, namely, standard (n = 961), scleral (n = 266), sinking (n = 151), retracted (n = 3), and fish (n = 3). The authors devised a new prospective measurement method for assessing blepharoptosis in a clinical setting. Graphical comparisons between the devised method of measuring VIP and mathematical estimations showed that the devised method is easier, more practical, and more precise for measuring degree of blepharoptosis from general population trends, and that VIP also provides a useful objective index for evaluating the postoperative results of blepharoptosis.

The expression and comparison of healthy and ptotic upper eyelid contours using a polynomial mathematical function.

PubMed

Mocan, Mehmet C; Ilhan, Hacer; Gurcay, Hasmet; Dikmetas, Ozlem; Karabulut, Erdem; Erdener, Ugur; Irkec, Murat

2014-06-01

To derive a mathematical expression for the healthy upper eyelid (UE) contour and to use this expression to differentiate the normal UE curve from its abnormal configuration in the setting of blepharoptosis. The study was designed as a cross-sectional study. Fifty healthy subjects (26M/24F) and 50 patients with blepharoptosis (28M/22F) with a margin-reflex distance (MRD1) of ≤2.5 mm were recruited. A polynomial interpolation was used to approximate UE curve. The polynomial coefficients were calculated from digital eyelid images of all participants using a set of operator defined points along the UE curve. Coefficients up to the fourth-order polynomial, iris area covered by the UE, iris area covered by the lower eyelid and total iris area covered by both the upper and the lower eyelids were defined using the polynomial function and used in statistical comparisons. The t-test, Mann-Whitney U test and the Spearman's correlation test were used for statistical comparisons. The mathematical expression derived from the data of 50 healthy subjects aged 24.1 ± 2.6 years was defined as y = 22.0915 + (-1.3213)x + 0.0318x(2 )+ (-0.0005x)(3). The fifth and the consecutive coefficients were <0.00001 in all cases and were not included in the polynomial function. None of the first fourth-order coefficients of the equation were found to be significantly different in male versus female subjects. In normal subjects, the percentage of the iris area covered by upper and lower lids was 6.46 ± 5.17% and 0.66% ± 1.62%, respectively. All coefficients and mean iris area covered by the UE were significantly different between healthy and ptotic eyelids. The healthy and abnormal eyelid contour can be defined and differentiated using a polynomial mathematical function.

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

NASA Astrophysics Data System (ADS)

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).

The vestibulosympathetic reflex in humans: neural interactions between cardiovascular reflexes

NASA Technical Reports Server (NTRS)

Ray, Chester A.; Monahan, Kevin D.

2002-01-01

1. Over the past 5 years, there has been emerging evidence that the vestibular system regulates sympathetic nerve activity in humans. We have studied this issue in humans by using head-down rotation (HDR) in the prone position. 2. These studies have clearly demonstrated increases in muscle sympathetic nerve activity (MSNA) and calf vascular resistance during HDR. These responses are mediated by engagement of the otolith organs and not the semicircular canals. 3. However, differential activation of sympathetic nerve activity has been observed during HDR. Unlike MSNA, skin sympathetic nerve activity does not increase with HDR. 4. Examination of the vestibulosympathetic reflex with other cardiovascular reflexes (i.e. barorereflexes and skeletal muscle reflexes) has shown an additive interaction for MSNA. 5. The additive interaction between the baroreflexes and vestibulosympathetic reflex suggests that the vestibular system may assist in defending against orthostatic challenges in humans by elevating MSNA beyond that of the baroreflexes. 6. In addition, the further increase in MSNA via otolith stimulation during isometric handgrip, when arterial pressure is elevated markedly, indicates that the vestibulosympathetic reflex is a powerful activator of MSNA and may contribute to blood pressure and flow regulation during dynamic exercise. 7. Future studies will help evaluate the importance of the vestibulosympathetic reflex in clinical conditions associated with orthostatic hypotension.

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

PubMed

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.

The effect of operant-conditioning balance training on the down-regulation of spinal H-reflexes in a spastic patient.

PubMed

Hoseini, Najmeh; Koceja, David M; Riley, Zachary A

2011-10-24

Spasticity in chronic hemiparetic stroke patients has primarily been treated pharmacologically. However, there is increasing evidence that physical rehabilitation can help manage hyper-excitability of reflexes (hyperreflexia), which is a primary contributor to spasticity. In the present study, one chronic hemiparetic stroke patient operantly conditioned the soleus H-reflex while training on a balance board for two weeks. The results showed a minimal decrease in the Hmax-Mmax ratio for both the affected and unaffected limb, indicating that the H-reflex was not significantly altered with training. Alternatively, paired-reflex depression (PRD), a measure of history-dependent changes in reflex excitability, could be conditioned. This was evident by the rightward shift and decreased slope of reflex excitability in the affected limb. The non-affected limb decreased as well, although the non-affected limb was very sensitive to PRD initially, whereas the affected limb was not. Based on these results, it was concluded that PRD is a better index of hyperreflexia, and this measurement could be more informative of synapse function than simple H-reflexes. This study presents a novel and non-pharmacological means of managing spasticity that warrants further investigation with the potential of being translated to the clinic. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Abatement costs of soil conservation in China's Loess Plateau: balancing income with conservation in an agricultural system.

PubMed

Hou, Lingling; Hoag, Dana L K; Keske, Catherine M H

2015-02-01

This study proposes the use of marginal abatement cost curves to calculate environmental damages of agricultural systems in China's Loess Plateau. Total system costs and revenues, management characteristics and pollution attributes are imputed into a directional output distance function, which is then used to determine shadow prices and abatement cost curves for soil and nitrogen loss. Marginal abatement costs curves are an effective way to compare economic and conservation tradeoffs when field-specific data are scarce. The results show that sustainable agricultural practices can balance soil conservation and agricultural production; land need not be retired, as is current policy. Published by Elsevier Ltd.

Passive margins getting squeezed in the mantle convection vice

NASA Astrophysics Data System (ADS)

Yamato, Philippe; Husson, Laurent; Becker, Thorsten W.; Pedoja, Kevin

2014-05-01

Passive margins often exhibit uplift, exhumation and tectonic inversion. We speculate that the compression in the lithosphere gradually increased during the Cenozoic. In the same time, the many mountain belts at active margins that accompany this event seem readily witness this increase. However, how that compression increase affects passive margins remains unclear. In order to address this issue, we design a 2D viscous numerical model wherein a lithospheric plate rests above a weaker mantle. It is driven by a mantle conveyor belt, alternatively excited by a lateral downwelling on one side, an upwelling on the other side, or both simultaneously. The lateral edges of the plate are either free or fixed, representing the cases of free convergence, and collision or slab anchoring, respectively. This distinction changes the upper boundary condition for mantle circulation and, as a consequence, the stress field. Our results show that between these two regimes, the flow pattern transiently evolves from a free-slip convection mode towards a no-slip boundary condition above the upper mantle. In the second case, the lithosphere is highly stressed horizontally and deforms. For an equivalent bulk driving force, compression increases drastically at passive margins provided that upwellings are active. Conversely, if downwellings alone are activated, compression occurs at short distances from the trench and extension prevails elsewhere. These results are supported by Earth-like 3D spherical models that reveal the same pattern, where active upwellings are required to excite passive margins compression. These results support the idea that compression at passive margins, is the response to the underlying mantle flow, that is increasingly resisted by the Cenozoic collisions.

Generalized versus partial reflex seizures: a review.

PubMed

Italiano, Domenico; Ferlazzo, Edoardo; Gasparini, Sara; Spina, Edoardo; Mondello, Stefania; Labate, Angelo; Gambardella, Antonio; Aguglia, Umberto

2014-08-01

In this review we assess our currently available knowledge about reflex seizures with special emphasis on the difference between "generalized" reflex seizures induced by visual stimuli, thinking, praxis and language tasks, and "focal" seizures induced by startle, eating, music, hot water, somatosensory stimuli and orgasm. We discuss in particular evidence from animal, clinical, neurophysiological and neuroimaging studies supporting the concept that "generalized" reflex seizures, usually occurring in the setting of IGE, should be considered as focal seizures with quick secondary generalization. We also review recent advances in genetic and therapeutic approach of reflex seizures. Copyright © 2014 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Electromechanical analogs of human reflexes.

PubMed

Littman, M G; Liker, M; Stubbeman, W; Russakow, J; McGee, C; Gelfand, J; Call, B J

1989-01-01

The conclusion to be drawn from our modeling is that the combined stretch and tendon reflexes alone can endow artificial muscle with a springlike feel as well as give it a baseline tone. In response to questions that motor physiologists often ask as to what variables the system controls, the answer here is clear: the stretch and tendon reflexes act together to maintain both a tension set-point and a length set-point, but in so doing they also give the system a springlike feel because of the existence of a servo error. The main goal of our studies is to understand the integration of reflexes, and thus far we have only begun to explore the two lowest-level spinal reflexes. We are in the process of expanding this work by developing a much more refined arm explicitly modeled after the human arm. This new arm is to be activated by a minimum of 10 muscles, each of which is reflexively driven, and it will allow us to explore the integration of higher-level reflex action such as automatic inhibition of antagonists and facilitation of synergists.

Effects of ankle joint position and submaximal muscle contraction intensity on soleus H-reflex modulation in young and older adults.

PubMed

Chen, Yung-Sheng; Zhou, Shi; Cartwright, Colleen

2014-04-01

This study investigated the effects of ankle joint position and submaximal contraction intensity on soleus (SOL) H-reflex modulation. Twenty young (25.1 ± 4.8 years) and 20 older adults (74.2 ± 5.1 years) performed plantar flexions during 10%, 30% and 50% maximal voluntary contractions (MVC) and at ankle positions of neutral (0°), plantar flexion (20°) and dorsiflexion (-20°) in a sitting position. The SOL H-reflex gain in older adults was relatively lower than that in young adults during 10%, 30% and 50% MVC. The SOL H-reflex gain was significantly affected by the intensity of plantar flexion in the respective ankle joint position in both age groups. The latency of H-reflex was prolonged in older adults and was ankle joint dependent in young adults. Young adults demonstrated a shorter duration of the H-reflex response than that of older adults. The results indicated that there were age-related changes in the SOL H-reflex during the ankle plantar flexors activities.

Acoustic Reflexes in Normal-Hearing Adults, Typically Developing Children, and Children with Suspected Auditory Processing Disorder: Thresholds, Real-Ear Corrections, and the Role of Static Compliance on Estimates.

PubMed

Saxena, Udit; Allan, Chris; Allen, Prudence

2017-06-01

Previous studies have suggested elevated reflex thresholds in children with auditory processing disorders (APDs). However, some aspects of the child's ear such as ear canal volume and static compliance of the middle ear could possibly affect the measurements of reflex thresholds and thus impact its interpretation. Sound levels used to elicit reflexes in a child's ear may be higher than predicted by calibration in a standard 2-cc coupler, and lower static compliance could make visualization of very small changes in impedance at threshold difficult. For this purpose, it is important to evaluate threshold data with consideration of differences between children and adults. A set of studies were conducted. The first compared reflex thresholds obtained using standard clinical procedures in children with suspected APD to that of typically developing children and adults to test the replicability of previous studies. The second study examined the impact of ear canal volume on estimates of reflex thresholds by applying real-ear corrections. Lastly, the relationship between static compliance and reflex threshold estimates was explored. The research is a set of case-control studies with a repeated measures design. The first study included data from 20 normal-hearing adults, 28 typically developing children, and 66 children suspected of having an APD. The second study included 28 normal-hearing adults and 30 typically developing children. In the first study, crossed and uncrossed reflex thresholds were measured in 5-dB step size. Reflex thresholds were analyzed using repeated measures analysis of variance (RM-ANOVA). In the second study, uncrossed reflex thresholds, real-ear correction, ear canal volume, and static compliance were measured. Reflex thresholds were measured using a 1-dB step size. The effect of real-ear correction and static compliance on reflex threshold was examined using RM-ANOVA and Pearson correlation coefficient, respectively. Study 1 replicated previous studies showing elevated reflex thresholds in many children with suspected APD when compared to data from adults using standard clinical procedures, especially in the crossed condition. The thresholds measured in children with suspected APD tended to be higher than those measured in the typically developing children. There were no significant differences between the typically developing children and adults. However, when real-ear calibrated stimulus levels were used, it was found that children's thresholds were elicited at higher levels than in the adults. A significant relationship between reflex thresholds and static compliance was found in the adult data, showing a trend for higher thresholds in ears with lower static compliance, but no such relationship was found in the data from the children. This study suggests that reflex measures in children should be adjusted for real-ear-to-coupler differences before interpretation. The data in children with suspected APD support previous studies suggesting abnormalities in reflex thresholds. The lack of correlation between threshold and static compliance estimates in children as was observed in the adults may suggest a nonmechanical explanation for age and clinically related effects. American Academy of Audiology

Biosonar behaviour of free-ranging porpoises

PubMed Central

Akamatsu, Tomonari; Wang, Ding; Wang, Kexiong; Naito, Yasuhiko

2005-01-01

Detecting objects in their paths is a fundamental perceptional function of moving organisms. Potential risks and rewards, such as prey, predators, conspecifics or non-biological obstacles, must be detected so that an animal can modify its behaviour accordingly. However, to date few studies have considered how animals in the wild focus their attention. Dolphins and porpoises are known to actively use sonar or echolocation. A newly developed miniature data logger attached to a porpoise allows for individual recording of acoustical search efforts and inspection distance based on echolocation. In this study, we analysed the biosonar behaviour of eight free-ranging finless porpoises (Neophocaena phocaenoides) and demonstrated that these animals inspect the area ahead of them before swimming silently into it. The porpoises inspected distances up to 77 m, whereas their swimming distance without using sonar was less than 20 m. The inspection distance was long enough to ensure a wide safety margin before facing real risks or rewards. Once a potential prey item was detected, porpoises adjusted their inspection distance from the remote target throughout their approach. PMID:15888412

Learning Human Actions by Combining Global Dynamics and Local Appearance.

PubMed

Luo, Guan; Yang, Shuang; Tian, Guodong; Yuan, Chunfeng; Hu, Weiming; Maybank, Stephen J

2014-12-01

In this paper, we address the problem of human action recognition through combining global temporal dynamics and local visual spatio-temporal appearance features. For this purpose, in the global temporal dimension, we propose to model the motion dynamics with robust linear dynamical systems (LDSs) and use the model parameters as motion descriptors. Since LDSs live in a non-Euclidean space and the descriptors are in non-vector form, we propose a shift invariant subspace angles based distance to measure the similarity between LDSs. In the local visual dimension, we construct curved spatio-temporal cuboids along the trajectories of densely sampled feature points and describe them using histograms of oriented gradients (HOG). The distance between motion sequences is computed with the Chi-Squared histogram distance in the bag-of-words framework. Finally we perform classification using the maximum margin distance learning method by combining the global dynamic distances and the local visual distances. We evaluate our approach for action recognition on five short clips data sets, namely Weizmann, KTH, UCF sports, Hollywood2 and UCF50, as well as three long continuous data sets, namely VIRAT, ADL and CRIM13. We show competitive results as compared with current state-of-the-art methods.

What is a reflex? A guide for understanding disorders of consciousness.

PubMed

Fischer, David B; Truog, Robert D

2015-08-11

Uncertainty in diagnosing disorders of consciousness, and specifically in determining whether consciousness has been lost or retained, poses challenging scientific and ethical questions. Recent neuroimaging-based tests for consciousness have cast doubt on the reliability of behavioral criteria in assessing states of consciousness and generate new questions about the assumptions used in formulating coherent diagnostic criteria. The reflex, a foundational diagnostic tool, offers unique insight into these disorders; behaviors produced by unconscious patients are thought to be purely reflexive, whereas those produced by conscious patients can be volitional. Further investigation, however, reveals that reflexes cannot be reliably distinguished from conscious behaviors on the basis of any generalizable empirical characteristics. Ambiguity between reflexive and conscious behaviors undermines the capacity of the reflex to distinguish between disorders of consciousness and has implications for how these disorders should be conceptualized in future diagnostic criteria. © 2015 American Academy of Neurology.

When planning results in loss of control: intention-based reflexivity and working-memory

PubMed Central

Meiran, Nachshon; Cole, Michael W.; Braver, Todd S.

2012-01-01

In this review, the authors discuss the seemingly paradoxical loss of control associated with states of high readiness to execute a plan, termed “intention-based reflexivity.” The review suggests that the neuro-cognitive systems involved in the preparation of novel plans are different than those involved in preparation of practiced plans (i.e., those that have been executed beforehand). When the plans are practiced, intention-based reflexivity depends on the prior availability of response codes in long-term memory (LTM). When the plans are novel, reflexivity is observed when the plan is pending and the goal has not yet been achieved. Intention-based reflexivity also depends on the availability of working-memory (WM) limited resources and the motivation to prepare. Reflexivity is probably related to the fact that, unlike reactive control (once a plan is prepared), proactive control tends to be relatively rigid. PMID:22586382

An Intelligent Computerized Stretch Reflex Measurement System For Clinical And Investigative Neurology

NASA Astrophysics Data System (ADS)

Flanagan, P. M.; Chutkow, J. G.; Riggs, M. T.; Cristiano, V. D.

1987-05-01

We describe the design of a reliable, user-friendly preprototype system for quantifying the tendon stretch reflexes in humans and large mammals. A hand-held, instrumented reflex gun, the impactor of which contains a single force sensor, interfaces with a computer. The resulting test system can deliver sequences of reproducible stimuli at graded intensities and adjustable durations to a muscle's tendon ("tendon taps"), measure the impacting force of each tap, and record the subsequent reflex muscle contraction from the same tendon -- all automatically. The parameters of the reflex muscle contraction include latency; mechanical threshold; and peak time, peak magnitude, and settling time. The results of clinical tests presented in this paper illustrate the system's potential usefulness in detecting neurologic dysfunction affecting the tendon stretch reflexes, in documenting the course of neurologic illnesses and their response to therapy, and in clinical and laboratory neurologic research.

Primate translational vestibuloocular reflexes. IV. Changes after unilateral labyrinthectomy

NASA Technical Reports Server (NTRS)

Angelaki, D. E.; Newlands, S. D.; Dickman, J. D.

2000-01-01

The effects of unilateral labyrinthectomy on the properties of the translational vestibuloocular reflexes (trVORs) were investigated in rhesus monkeys trained to fixate near targets. Translational motion stimuli consisted of either steady-state lateral and fore-aft sinusoidal oscillations or short-lasting transient displacements. During small-amplitude, steady-state sinusoidal lateral oscillations, a small decrease in the horizontal trVOR sensitivity and its dependence on viewing distance was observed during the first week after labyrinthectomy. These deficits gradually recovered over time. In addition, the vertical response component increased, causing a tilt of the eye velocity vector toward the lesioned side. During large, transient lateral displacements, the deficits were larger and longer lasting. Responses after labyrinthectomy were asymmetric, with eye velocity during movements toward the side of the lesion being more compromised. The most profound effect of the lesions was observed during fore-aft motion. Whereas responses were kinematically appropriate for fixation away from the side of the lesion (e.g., to the left after right labyrinthectomy), horizontal responses were anticompensatory during fixation at targets located ipsilateral to the side of the lesion (e.g., for targets to the right after right labyrinthectomy). This deficit showed little recovery during the 3-mo post-labyrinthectomy testing period. These results suggest that inputs from both labyrinths are important for the proper function of the trVORs, although the details of how bilateral signals are processed and integrated remain unknown.

Dynamic Features for Iris Recognition.

PubMed

da Costa, R M; Gonzaga, A

2012-08-01

The human eye is sensitive to visible light. Increasing illumination on the eye causes the pupil of the eye to contract, while decreasing illumination causes the pupil to dilate. Visible light causes specular reflections inside the iris ring. On the other hand, the human retina is less sensitive to near infra-red (NIR) radiation in the wavelength range from 800 nm to 1400 nm, but iris detail can still be imaged with NIR illumination. In order to measure the dynamic movement of the human pupil and iris while keeping the light-induced reflexes from affecting the quality of the digitalized image, this paper describes a device based on the consensual reflex. This biological phenomenon contracts and dilates the two pupils synchronously when illuminating one of the eyes by visible light. In this paper, we propose to capture images of the pupil of one eye using NIR illumination while illuminating the other eye using a visible-light pulse. This new approach extracts iris features called "dynamic features (DFs)." This innovative methodology proposes the extraction of information about the way the human eye reacts to light, and to use such information for biometric recognition purposes. The results demonstrate that these features are discriminating features, and, even using the Euclidean distance measure, an average accuracy of recognition of 99.1% was obtained. The proposed methodology has the potential to be "fraud-proof," because these DFs can only be extracted from living irises.

Conceptual design study of improved 1985 remote lift-fan V/STOL commercial transports

NASA Technical Reports Server (NTRS)

Cavage, R. L.

1975-01-01

A design study was conducted for a remote lift-fan commercial V/STOL transport for the 1985 time period. The investigation centered on the commercial short haul transportation application to carry 100 passengers over trip distances of 400 nautical miles from a vertical takeoff and landing, and 800 nautical miles after a 1600 foot STOL takeoff. The study included investigation of alternate numbers and arrangements of lift fans and gas generators, fan control margins, and structural concepts. The sensitivity of direct operating costs to major airframe parameters, airframe costs, propulsion costs, yearly aircraft utilization rate, and trip distances are evaluated.

Abutment height influences the effect of platform switching on peri-implant marginal bone loss.

PubMed

Galindo-Moreno, Pablo; León-Cano, Ana; Monje, Alberto; Ortega-Oller, Inmaculada; O'Valle, Francisco; Catena, Andrés

2016-02-01

The purpose was to radiographically analyze and compare the marginal bone loss (MBL) between implants with different mismatching distance and to study the influence of the prosthetic abutment height on the MBL in association with the related mismatching distances. This retrospective study included 108 patients in whom 228 implants were placed, 180 with diameter of 4.5 mm and 48 with diameter of 5 mm. All patients received OsseoSpeed™ implants with internal tapered conical connection (Denstply Implants). Different mismatching distances were obtained, given that all implants were loaded with the same uni-abutment type (Lilac; Denstply Implants). Data were gathered on age, gender, bone substratum, smoking habits, previous history of periodontitis, and prosthetic features. MBL was analyzed radiographically at 6 and 18 months post-loading. Mixed linear analysis of mesial and distal MBL values yielded significant effects of abutment, implant diameter, follow-up period, bone substratum, smoking, and abutment × time interaction. MBL was greater at 18 vs. 6 months, for short vs. long abutments, for grafted vs. pristine bone, for a heavier smoking habit, and for implants with a diameter of 5.0 vs. 4.5 mm. Greater mismatching does not minimize the MBL; abutment height, smoking habit, and bone substratum may play a role in the MBL over the short- and medium term. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Evaluation of the relation between triceps surae H-reflex, M-response latencies and thigh length in normal population.

PubMed

Khosrawi, Saeid; Fallah, Salman

2013-03-01

The H-reflex is a useful electrophysiological procedure for evaluating the status of the peripheral nervous system, especially at the proximal segment of the peripheral nerve. The purpose of this study is to investigate the relation between triceps surae H-reflex and M- response latencies and thigh length in normal population, in order to determine if there is any regression equation between them. After screening 75 volunteers by considering inclusion and exclusion criteria, 72 of them were selected to enroll into our study (34 men and 38 women with the mean age of 36.04 ± 7.7 years). In all of the subjects H-reflex and M-response latencies were recorded by standard electrophysiological techniques and thigh length was measured. Finally, our data was analyzed for its relations with respect to ages in both sexes by appropriate statistical and mathematical methods. Mean ± SD for H-reflex latency was 27.94 ± 1.6 ms. We found a significant correlation between H-reflex latency and M-latency (r = 0.28), no significant correlation was found between H-reflex latency and thigh length (r = -0.051). Finally based on our findings we introduce a new formula in this paper. We found a significant correlation among of M-response latency and other variables (H-reflex latency and thigh length). Despite this it was eliminated from our formula. The relationship between H-reflex latency and age was significant. Further studies are required to delineate the clinical usage and interpretation of the formula, which we found in this study.

Comparison of voluntary and reflex cough effectiveness in Parkinson’s disease

PubMed Central

Hegland, Karen Wheeler; Troche, Michelle S.; Brandimore, Alexandra E.; Davenport, Paul W.; Okun, Michael S.

2016-01-01

Introduction Multiple airway protective mechanisms are impacted with Parkinson’s disease (PD), including swallowing and cough. Cough serves to eject material from the lower airways, and can be produced voluntarily (on command) and reflexively in response to aspirate material or other airway irritants. Voluntary cough effectiveness is reduced in PD however it is not known whether reflex cough is affected as well. The goal of this study was to compare the effectiveness between voluntary and reflex cough in patients with idiopathic PD. Methods Twenty patients with idiopathic PD participated. Cough airflow data were recorded via facemask in line with a pneumotachograph. A side delivery port connected the nebulizer for delivery of capsaicin, which was used to induce cough. Three voluntary coughs and three reflex coughs were analyzed from each participant. A two-way repeated measures analysis of variance was used to compare voluntary versus reflex cough airflow parameters. Results Significant differences were found for peak expiratory flow rate (PEFR) and cough expired volume (CEV) between voluntary and reflex cough. Specifically, both PEFR and CEV were reduced for reflex as compared to voluntary cough. Conclusion Cough PEFR and CEV are indicative of cough effectiveness in terms of the ability to remove material from the lower airways. Differences between these two cough types likely reflect differences in the coordination of the respiratory and laryngeal subsystems. Clinicians should be aware that evaluation of cough function using voluntary cough tasks overestimates the PEFR and CEV that would be achieved during reflex cough in patients with PD. PMID:25246315

[Comparative study on the reflex responses of carotid and aortic baroreceptors in the rabbit].

PubMed

Li, Z; Ho, S Y

1989-08-01

In 81 anesthetized rabbits, the baroreflex control of heart rate (HR), hind-limb vascular resistance (HVR) and renal sympathetic nerve activity (RSNA) was observed during arterial baroreceptor loading and unloading by intravenously injecting phenylephrine (PE) and nitroprusside (NP). The results were as follows: (1) An increase of arterial pressure with PE caused reduction in HR, HVR and RSNA, while a decrease of arterial pressure with NP evoked opposite responses. These reflex responses were reproducible. (2) By either carotid baroreceptor denervation (CBRX) or aortic baroreceptor denervation (ABRX), the reflex changes of HR induced by injecting PE and NP were impaired (P less than 0.01), while the reflex responses in HVP remained unchanged. Despite of the enhanced basal RSNA following ABRX or CBRX, the magnitude of reflex inhibition in RSNA during injecting NP was similar to that before denervation, whereas that of the reflex excitation in RSNA during injecting NP was reduced (P less than 0.05). (3) After complete sino-aortic denervation (SAD), the change of arterial pressure following PE or NP injection was enhanced, but the reflex changes in HR, HVR and RSNA were significantly diminished (P less than 0.001). (4) Vagotomy abolished the residual reflex changes observed after SAD. The results indicate that the aortic and carotid baroreceptors may regulate HR in a simple additive manner, while the aortic baroreceptor seems to be more important. Furthermore, both the aortic and carotid baroreceptors may play important roles for the reflex control of HVR and RSNA, and operate mutually by the way of inhibitory summation.

The Dynamics of Successive Induction in Larval Zebrafish

EPA Science Inventory

Charles Sherrington identified the properties of the synapse by purely behavioral means the study of reflexes -more than 100 years ago. They were subsequently confirmed neurophysiologically. Studying reflex interaction, he also showed that activating one reflex often facilitates...

Activity in the primary somatosensory cortex induced by reflexological stimulation is unaffected by pseudo-information: a functional magnetic resonance imaging study

PubMed Central

2013-01-01

Background Reflexology is an alternative medical practice that produces beneficial effects by applying pressure to specific reflex areas. Our previous study suggested that reflexological stimulation induced cortical activation in somatosensory cortex corresponding to the stimulated reflex area; however, we could not rule out the possibility of a placebo effect resulting from instructions given during the experimental task. We used functional magnetic resonance imaging (fMRI) to investigate how reflexological stimulation of the reflex area is processed in the primary somatosensory cortex when correct and pseudo-information about the reflex area is provided. Furthermore, the laterality of activation to the reflexological stimulation was investigated. Methods Thirty-two healthy Japanese volunteers participated. The experiment followed a double-blind design. Half of the subjects received correct information, that the base of the second toe was the eye reflex area, and pseudo-information, that the base of the third toe was the shoulder reflex area. The other half of the subjects received the opposite information. fMRI time series data were acquired during reflexological stimulation to both feet. The experimenter stimulated each reflex area in accordance with an auditory cue. The fMRI data were analyzed using a conventional two-stage approach. The hemodynamic responses produced by the stimulation of each reflex area were assessed using a general linear model on an intra-subject basis, and a two-way repeated-measures analysis of variance was performed on an intersubject basis to determine the effect of reflex area laterality and information accuracy. Results Our results indicated that stimulation of the eye reflex area in either foot induced activity in the left middle postcentral gyrus, the area to which tactile sensation to the face projects, as well as in the postcentral gyrus contralateral foot representation area. This activity was not affected by pseudo information. The results also indicate that the relationship between the reflex area and the projection to the primary somatosensory cortex has a lateral pattern that differs from that of the actual somatotopical representation of the body. Conclusion These findings suggest that a robust relationship exists between neural processing of somatosensory percepts for reflexological stimulation and the tactile sensation of a specific reflex area. PMID:23711332

Child-Computer Interaction at the Beginner Stage of Music Learning: Effects of Reflexive Interaction on Children's Musical Improvisation.

PubMed

Addessi, Anna Rita; Anelli, Filomena; Benghi, Diber; Friberg, Anders

2017-01-01

In this article children's musical improvisation is investigated through the "reflexive interaction" paradigm. We used a particular system, the MIROR-Impro, implemented in the framework of the MIROR project (EC-FP7), which is able to reply to the child playing a keyboard by a "reflexive" output, mirroring (with repetitions and variations) her/his inputs. The study was conducted in a public primary school, with 47 children, aged 6-7. The experimental design used the convergence procedure, based on three sample groups allowing us to verify if the reflexive interaction using the MIROR-Impro is necessary and/or sufficient to improve the children's abilities to improvise. The following conditions were used as independent variables: to play only the keyboard, the keyboard with the MIROR-Impro but with not-reflexive reply, the keyboard with the MIROR-Impro with reflexive reply. As dependent variables we estimated the children's ability to improvise in solos, and in duets. Each child carried out a training program consisting of 5 weekly individual 12 min sessions. The control group played the complete package of independent variables; Experimental Group 1 played the keyboard and the keyboard with the MIROR-Impro with not-reflexive reply; Experimental Group 2 played only the keyboard with the reflexive system. One week after, the children were asked to improvise a musical piece on the keyboard alone (Solo task), and in pairs with a friend (Duet task). Three independent judges assessed the Solo and the Duet tasks by means of a grid based on the TAI-Test for Ability to Improvise rating scale. The EG2, which trained only with the reflexive system, reached the highest average results and the difference with EG1, which did not used the reflexive system, is statistically significant when the children improvise in a duet. The results indicate that in the sample of participants the reflexive interaction alone could be sufficient to increase the improvisational skills, and necessary when they improvise in duets. However, these results are in general not statistically significant. The correlation between Reflexive Interaction and the ability to improvise is statistically significant. The results are discussed on the light of the recent literature in neuroscience and music education.

The Middle Ear Muscle Reflex in Rat: Developing a Biomarker of Auditory Nerve Degeneration.

PubMed

Chertoff, Mark E; Martz, Ashley; Sakumura, Joey T; Kamerer, Aryn M; Diaz, Francisco

The long-term goal of this research is to determine whether the middle ear muscle reflex can be used to predict the number of healthy auditory nerve fibers in hearing-impaired ears. In this study, we develop a high-impedance source and an animal model of the middle ear muscle reflex and explore the influence of signal frequency and level on parameters of the reflex to determine an optimal signal to examine auditory nerve fiber survival. A high-impedance source was developed using a hearing aid receiver attached to a 0.06 diameter 10.5-cm length tube. The impedance probe consisted of a microphone probe placed near the tip of a tube coupled to a sound source. The probe was calibrated by inserting it into a syringe of known volumes and impedances. The reflex in the anesthetized rat was measured with elicitor stimuli ranging from 3 to 16 kHz presented at levels ranging from 35 to 100 dB SPL to one ear while the reflex was measured in the opposite ear containing the probe and probe stimulus. The amplitude of the reflex increased with elicitor level and was largest at 3 kHz. The lowest threshold was approximately 54 dB SPL for the 3-kHz stimulus. The rate of decay of the reflex was greatest at 16 kHz followed by 10 and 3 kHz. The rate of decay did not change significantly with elicitor signal level for 3 and 16 kHz, but decreased as the level of the 10-kHz elicitor increased. A negative feedback model accounts for the reflex decay by having the strength of feedback dependent on auditory nerve input. The rise time of the reflex varied with frequency and changed with level for the 10- and 16-kHz signals but not significantly for the 3-kHz signal. The latency of the reflex increased with a decrease in elicitor level, and the change in latency with level was largest for the 10-kHz stimulus. Because the amplitude of the reflex in rat was largest with an elicitor signal at 3 kHz, had the lowest threshold, and yielded the least amount of decay, this may be the ideal frequency to estimate auditory nerve survival in hearing-impaired ears.

Portraying Reflexivity in Health Services Research.

PubMed

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.

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

PubMed Central

Sanghera, Balihar

2016-01-01

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. PMID:28232772

Underwater Noise and the Conservation of Divers’ Hearing: A Review. Volume 1

DTIC Science & Technology

1989-10-01

reflex attenuation, since the tensor tympani is unaffected and since Bell ’ palsy may affect the VIIIth (auditory) nerve as well as the VIlth (facial...studied acoustic reflexes in patients with acute facial nerve paralysis (Bell’s palsy ). These patients had absent stapedius reflexes on the side of the...voluntary middle ear muscle activation. 24 Bell’s palsy cases; attenuation estimated by shift in reflex amplitude- intensity functions (contralateral), re

Assessment of H reflex sensitivity with M wave alternation consequent to fatiguing contractions.

PubMed

Hwang, Ing-Shiou; Huang, Cheng-Ya; Wu, Pei-Shan; Chen, Yi-Ching; Wang, Chun-Hou

2008-09-01

The objective of this study was to examine the changes in H reflex sensitivity after neuromuscular fatigue associated with fluctuations of the M wave. In the maximal and submaximal voluntary contraction (MVC and SMVC) paradigms, subjects performed voluntary plantarflexion at 100% MVC and 40% MVC respectively until the limit of torque maintenance was reached. In the submaximal electrical stimulation (SMES) paradigm, the tricep surae was exhausted with sustained electrical stimulation of 40% of the maximal tolerable intensity at a 40-Hz stimulus rate. The H reflexes and maximal M waves (M(max)) of the soleus were recorded before and after the three fatigue paradigms, and the H reflex was standardized with M(max) to minimize possible bias due to fatigue-induced M wave fluctuation. The results showed a significant increase in the standardized H reflex due to the SMES paradigm in spite of M(max) potentiation. The SMVC paradigm led to a reduction in size of the standardized H reflex without modification of M(max), whereas the standardized H reflex was not mediated by the MVC paradigm, which contributed to a noticeable M(max) potentiation. The present study underscored the fact that the H reflex sensitivity and M wave amplitude were not necessarily suppressed consequent to neuromuscular fatigue, but varied with the activation history of a muscle for size-dependent efficacy of the Ia transmission pathways and postactivation potentiation.

Correlations between grasp-reflex strengths and serum thyroid-hormone levels depending upon sex and familial sinistrality in human neonates: importance of genetically predetermined cerebral organization.

PubMed

Tan, U

1994-03-01

Relations of grasp-reflex strengths to serum free-thyroid hormone levels were studied in human neonates. In right-dominant (RH) males and females without familial sinistrality (-FS), grasp-reflex strengths from right (R) and left (L) inversely correlated with serum triiodothyronine (T3). In RH, +FS males, grasp-reflex strengths from R and L hands directly correlated with T3 (no correlations in RH, +FS females). There was no significant correlation between grasp reflex and T3 in non-right-handed (NRH), -FS neonates. In NRH +FS neonates, there was a significant negative linear correlation between grasp reflex from left and T3 only in NRH, +FS males. The following correlations were found between grasp reflex and thyroxine (T4): direct relation in RH, +FS males and females; inverse relation in NRH, -FS females only for the right hand; inverse correlations in NRH, +FS females. The R-L grasp reflex directly correlated with T3 in RH, -FS males, and inversely correlated with T3 in RH, -FS females (no significant correlations in others). These results indicated that thyroid hormones may influence cerebral maturation and lateralization differentially according to genetically predetermined cerebral organization. The generalizations of the hormonal effects on, at least, cerebral functioning would be wrong, if the genetically predetermined main features of the brain are neglected.

The Neuroanatomical Correlates of Training-Related Perceptuo-Reflex Uncoupling in Dancers

PubMed Central

Nigmatullina, Yuliya; Hellyer, Peter J.; Nachev, Parashkev; Sharp, David J.; Seemungal, Barry M.

2015-01-01

Sensory input evokes low-order reflexes and higher-order perceptual responses. Vestibular stimulation elicits vestibular-ocular reflex (VOR) and self-motion perception (e.g., vertigo) whose response durations are normally equal. Adaptation to repeated whole-body rotations, for example, ballet training, is known to reduce vestibular responses. We investigated the neuroanatomical correlates of vestibular perceptuo-reflex adaptation in ballet dancers and controls. Dancers' vestibular-reflex and perceptual responses to whole-body yaw-plane step rotations were: (1) Briefer and (2) uncorrelated (controls' reflex and perception were correlated). Voxel-based morphometry showed a selective gray matter (GM) reduction in dancers' vestibular cerebellum correlating with ballet experience. Dancers' vestibular cerebellar GM density reduction was related to shorter perceptual responses (i.e. positively correlated) but longer VOR duration (negatively correlated). Contrastingly, controls' vestibular cerebellar GM density negatively correlated with perception and VOR. Diffusion-tensor imaging showed that cerebral cortex white matter (WM) microstructure correlated with vestibular perception but only in controls. In summary, dancers display vestibular perceptuo-reflex dissociation with the neuronatomical correlate localized to the vestibular cerebellum. Controls' robust vestibular perception correlated with a cortical WM network conspicuously absent in dancers. Since primary vestibular afferents synapse in the vestibular cerebellum, we speculate that a cerebellar gating of perceptual signals to cortical regions mediates the training-related attenuation of vestibular perception and perceptuo-reflex uncoupling. PMID:24072889

Cutaneous inputs from the back abolish locomotor-like activity and reduce spastic-like activity in the adult cat following complete spinal cord injury

PubMed Central

Frigon, Alain; Thibaudier, Yann; Johnson, Michael D.; Heckman, C.J.; Hurteau, Marie-France

2012-01-01

Spasticity is a condition that can include increased muscle tone, clonus, spasms, and hyperreflexia. In this study, we report the effect of manually stimulating the dorsal lumbosacral skin on spontaneous locomotor-like activity and on a variety of reflex responses in 5 decerebrate chronic spinal cats treated with clonidine. Cats were spinalized 1 month before the terminal experiment. Stretch reflexes were evoked by stretching the left triceps surae muscles. Crossed reflexes were elicited by electrically stimulating the right tibial or superficial peroneal nerves. Windup of reflex responses was evoked by electrically stimulating the left tibial or superficial peroneal nerves. We found that pinching the skin of the back abolished spontaneous locomotor-like activity. We also found that back pinch abolished the rhythmic activity observed during reflex testing without eliminating the reflex responses. Some of the rhythmic episodes of activity observed during reflex testing were consistent with clonus with an oscillation frequency greater than 3 Hz. Pinching the skin of the back effectively abolished rhythmic activity occurring spontaneously or evoked during reflex testing, irrespective of oscillation frequency. The results are consistent with the hypothesis that locomotion and clonus are produced by common central pattern-generators. Stimulating the skin of the back could prove helpful in managing undesired rhythmic activity in spinal cord-injured humans. PMID:22487200

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

PubMed

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.

Modulation of H-Reflex Depression with Paired-Pulse Stimulation in Healthy Active Humans.

PubMed

Oza, Preeti D; Dudley-Javoroski, Shauna; Shields, Richard K

2017-01-01

Depression of the Hoffman reflex (H-reflex) is used to examine spinal control mechanisms during exercise, fatigue, and vibration and in response to training. H-reflex depression protocols frequently use trains of stimuli; this is time-consuming and prevents instantaneous assessment of motor neuronal excitability. The purpose of this study was to determine if paired-pulse H-reflex depression is reproducible and whether paired-pulse stimulation adequately estimates the depression induced by the more traditional ten-pulse train. H-reflexes were elicited via ten-pulse trains at 0.1, 0.2, 1, 2, and 5 Hz in ten neurologically intact individuals on two separate days. We measured the depression elicited by the second pulse (H2) and the mean depression elicited by pulses 2-10 (Hmean). H2 was consistent at all frequencies on both days ( r 2 = 0.97, p < 0.05, and ICC (3,1) = 0.81). H2 did not differ from Hmean ( p > 0.05). The results indicate that paired-pulse H-reflex depression has high between-day reliability and yields depression estimates that are comparable to those obtained via ten-pulse trains. Paired-pulse H-reflex depression may be especially useful for studies that require rapid assessment of motor neuronal excitability, such as during exercise, fatigue, and vibration, or to establish recovery curves following inhibition.

Regulation of muscle stiffness during periodic length changes in the isolated abdomen of the hermit crab.

PubMed

Chapple, W D

1997-09-01

Reflex activation of the ventral superficial muscles (VSM) in the abdomen of the hermit crab, Pagurus pollicarus, was studied using sinusoidal and stochastic longitudinal vibration of the muscle while recording the length and force of the muscle and the spike times of three exciter motoneurons. In the absence of vibration, the interspike interval histograms of the two larger motoneurons were bimodal; cutting sensory nerves containing most of the mechanoreceptor input removed the short interval peak in the histogram, indicating that the receptors are important in maintaining tonic firing. Vibration of the muscle evoked a reflex increase in motoneuron frequency that habituated after an initial peak but remained above control levels for the duration of stimulation. Motoneuron frequency increased with root mean square (rms) stimulus amplitude. Average stiffness during stimulation was about two times the stiffness of passive muscle. The reflex did not alter muscle dynamics. Estimated transfer functions were calculated from the fast Fourier transform of length and force signals. Coherence was >0.9 for the frequency range of 3-35 Hz. Stiffness magnitude gradually increased over this range in both reflex activated and passive muscle; phase was between 10 and 20 degrees. Reflex stiffness decreased with increasing stimulus amplitudes, but at larger amplitudes, this decrease was much less pronounced; in this range stiffness was regulated by the reflex. The sinusoidal frequency at which reflex bursts were elicited was approximately 6 Hz, consistent with previous measurements using ramp stretch. During reflex excitation, there was an increase in amplitude of the short interval peak in the interspike interval histogram; this was reduced when the majority of afferent pathways was removed. A phase histogram of motoneuron firing during sinusoidal vibration had a peak at approximately 110 ms, also suggesting that an important component of the reflex is via direct projections from the mechanoreceptors. These results are consistent with the hypothesis that a robust feedforward regulation of abdominal stiffness during continuous disturbances is achieved by mechanoreceptors signalling the absolute value of changing forces; habituation of the reflex, its high-threshold for low frequency disturbances and the activation kinetics of the muscle further modify reflex dynamics.

Localized Glacier Deformation Associated with Filling and Draining of a Glacier-Dammed Lake and Implications for Outburst Flood Hydraulics

NASA Astrophysics Data System (ADS)

Cunico, M. L.; Walder, J. S.; Fountain, A. G.; Trabant, D. C.

2001-12-01

During the summer of 2000, we measured displacements of 22 survey targets on the surface of Kennicott Glacier, Alaska, in the vicinity of Hidden Creek Lake, an ice-dammed lake in a tributary valley that fills and drains annually. Targets were distributed over a domain about equal in width to the lake, from near the glacier/lake margin to a distance of about 1 km from the margin. Targets were surveyed over a 24-day period as the lake filled and then drained. Lake stage was independently monitored. Vertical movement of targets generally fell off with distance d from the lake. As the lake filled, targets with d < 300 to 400 m rose at nearly the same rate as the lake--typically about 0.5 m/d--with a few targets rising slightly faster than the lake. The rate of vertical movement fell off rapidly with distance from the lake: for d = ca. 600 m--roughly twice the local ice thickness--targets moved upward only about 10% as fast as lake stage. Vertical movement of targets with d > ca. 1 km seemed to be uncorrelated with lake stage. The general pattern is consistent with the idea that a wedge of water extended beneath the glacier to a distance of perhaps 300 to 400 m from the visible margin of the lake and exerts buoyant stresses on the ice that were transmitted into the main body of the glacier and caused flexure. This scenario bears some resemblance to tidal deflections of ice shelves or tidewater glaciers. For a given value of lake stage, target elevations were invariably higher as the lake drained than as the lake filled. Moreover, survey targets at a distance of about 400 m or more from the lake continued to rise for some time even after the lake began to drain. The lag time between the beginning of lake drainage and the beginning of target downdrop increased with distance from the lake, with the lag being about 14 hours at a distance of 400 m from the lake. (The lake drained completely in approximately 75 hours.) The likeliest explanations for the departure from reversibility and the existence of the time lag are either (i) a "viscous" response of the glacier to the flexural stresses imposed by the subglacial water wedge, or (ii) movement of water from the lake into temporary storage--a sort of hydraulic jacking. We favor the latter explanation and suggest that as the lake drained, water "backed up" from a main drainage channel into a basal cavity system and perhaps englacial voids as well; the stored water then drained back out as pressure eventually fell in the main channel. Assuming that all the vertical downdrop of the ice is due to the evacuation of water, the total volume of the putative subglacial "wedge" plus the water released from distributed storage is about 7 to 11 million cubic meters, or about 25 to 40% of the volume of the subaerial lake.

Digital evaluation of absolute marginal discrepancy: A comparison of ceramic crowns fabricated with conventional and digital techniques.

PubMed

Liang, Shanshan; Yuan, Fusong; Luo, Xu; Yu, Zhuoren; Tang, Zhihui

2018-04-05

Marginal discrepancy is key to evaluating the accuracy of fixed dental prostheses. An improved method of evaluating marginal discrepancy is needed. The purpose of this in vitro study was to evaluate the absolute marginal discrepancy of ceramic crowns fabricated using conventional and digital methods with a digital method for the quantitative evaluation of absolute marginal discrepancy. The novel method was based on 3-dimensional scanning, iterative closest point registration techniques, and reverse engineering theory. Six standard tooth preparations for the right maxillary central incisor, right maxillary second premolar, right maxillary second molar, left mandibular lateral incisor, left mandibular first premolar, and left mandibular first molar were selected. Ten conventional ceramic crowns and 10 CEREC crowns were fabricated for each tooth preparation. A dental cast scanner was used to obtain 3-dimensional data of the preparations and ceramic crowns, and the data were compared with the "virtual seating" iterative closest point technique. Reverse engineering software used edge sharpening and other functional modules to extract the margins of the preparations and crowns. Finally, quantitative evaluation of the absolute marginal discrepancy of the ceramic crowns was obtained from the 2-dimensional cross-sectional straight-line distance between points on the margin of the ceramic crowns and the standard preparations based on the circumferential function module along the long axis. The absolute marginal discrepancy of the ceramic crowns fabricated using conventional methods was 115 ±15.2 μm, and 110 ±14.3 μm for those fabricated using the digital technique was. ANOVA showed no statistical difference between the 2 methods or among ceramic crowns for different teeth (P>.05). The digital quantitative evaluation method for the absolute marginal discrepancy of ceramic crowns was established. The evaluations determined that the absolute marginal discrepancies were within a clinically acceptable range. This method is acceptable for the digital evaluation of the accuracy of complete crowns. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Esophageal sensation in premature human neonates: temporal relationships and implications of aerodigestive reflexes and electrocortical arousals

PubMed Central

Parks, Vanessa N.; Peng, Juan; Dzodzomenyo, Samuel; Fernandez, Soledad; Shaker, Reza; Splaingard, Mark

2012-01-01

Electrocortical arousal (ECA) as an effect of visceral provocation or of its temporal relationships with aerodigestive reflexes in premature neonates is not known. We tested the hypothesis that esophageal provocation results in both esophageal reflex responses and ECAs during sleep and that ECAs are dependent on the frequency characteristics of esophageal neuromotor responses. We defined the spatiotemporal relationship of ECAs in relation to 1) spontaneous pharyngoesophageal swallow sequences and gastroesophageal reflux (GER) events and 2) sensory-motor characteristics of esophageal reflexes. Sixteen healthy premature neonates born at 27.9 ± 3.4 wk were tested at 36.8 ± 1.9 wk postmenstrual age. Ninety-five midesophageal and 31 sham stimuli were given in sleep during concurrent manometry and videopolysomnography. With stimulus onset as reference point, we scored the response latency, frequency occurrence and duration of arousals, peristaltic reflex, and upper esophageal sphincter contractile reflex (UESCR). Changes in polysomnography-respiratory patterns and esophageal sensory-motor parameters were scored by blinded observers. Significantly (for each characteristic listed, P < 0.05), swallow sequences were associated with arousals and sleep state changes, and arousals were associated with incomplete peristalsis, response delays to lower esophageal sphincter relaxation, and prolonged esophageal clearance. GER events (73.5%) provoked arousals, and arousals were associated with response delays to peristaltic reflexes or clearance, sleep state modification, and prolonged respiratory arousal. Midesophageal stimuli (54%) provoked arousals and were associated with increased frequency, prolonged latency, prolonged response duration of peristaltic reflexes and UESCR, and increased frequency of sleep state changes and respiratory arousals. In human neonates, ECAs are provoked upon esophageal stimulation; the sensory-motor characteristics of esophageal reflexes are distinct when accompanied by arousals. Aerodigestive homeostasis is defended by multiple tiers of aerodigestive safety mechanisms, and when esophageal reflexes are delayed, cortical hypervigilance (ECAs) occurs. PMID:21852361

Age-related differences in trunk muscle reflexive behaviors.

PubMed

Shojaei, Iman; Nussbaum, Maury A; Bazrgari, Babak

2016-10-03

Reports of larger passive and similar intrinsic trunk stiffness in older vs. younger populations suggest a diminishing demand for reflexive contributions of trunk muscles to spinal stability with aging. It remains unclear, though, whether such diminishing demands result in deterioration of trunk muscle reflexive behaviors. A cross-sectional study was completed to assess age-related differences in the latency and likelihood of trunk muscle reflexive responses to sudden perturbations. Sixty healthy individuals, aged 20-70 years, were recruited to form five equal-sized and gender-balanced age groups. Using a displacement-control, sudden perturbation paradigm, the latency and likelihood of trunk muscle reflexive responses to sudden perturbations were estimated, and the influences of age, gender, and level of effort (20% versus 30% of maximum voluntary exertion-MVE) were evaluated. There were no consistent age-related differences found in any of the measures of trunk muscle reflexive behavior. However, the latency of muscle response to perturbation was generally higher among older individuals, and this difference was significant in the condition involving 30% MVE effort. With an increase in level of effort (from 20% to 30% of MVE), there was a ~7% increase in the latency of trunk muscle responses to anteriorly-directed perturbations as well as ~ 15% (21%) decrease (increase) in response likelihood during anteriorly (posteriorly) directed perturbations. Furthermore, the reflexive response likelihood of trunk muscles was 28% (58%) larger (smaller) in female vs. male participants during anteriorly (posteriorly) directed perturbations. Our results did not, in general, support the hypothesis of an age-related decay in reflexive trunk muscle behaviors. Larger reflexive responses were associated with lower trunk intrinsic stiffness among females and during a lower level of effort, suggesting a secondary role for reflexive responses in spinal stability. Such secondary compensatory responses appear, however, to be consistent over a wide age range. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reflexive convention: civil partnership, marriage and family.

PubMed

Heaphy, Brian

2017-09-14

Drawing on an analysis of qualitative interview data from a study of formalized same-sex relationships (civil partnerships) this paper examines the enduring significance of marriage and family as social institutions. In doing so, it intervenes in current debates in the sociology of family and personal life about how such institutions are undermined by reflexivity or bolstered by convention. Against the backdrop of dominating sociological frames for understanding the links between the changing nature of marriage and family and same-sex relationship recognition, the paper analyses the diverse and overlapping ways (including the simple, relational, strategic, ambivalent and critical ways) in which same-sex partners reflexively constructed and engaged with marriage and family conventions. My analysis suggests that instead of viewing reflexivity and convention as mutually undermining, as some sociologists of family and personal life do, it is insightful to explore how diverse forms of reflexivity and convention interact in everyday life to reconfigure the social institutions of marriage and family, but do not undermine them as such. I argue the case for recognizing the ways in which 'reflexive convention', or reflexive investment in convention, contributes to the continuing significance of marriage and family as social institutions. © London School of Economics and Political Science 2017.

Two cases of Bezold-Jarisch reflex induced by intra-arterial nitroglycerin in critical left main coronary artery stenosis.

PubMed

Shah, Sachin P; Waxman, Sergio

2013-01-01

The Bezold-Jarisch reflex, a well-described phenomenon, occurs upon the stimulation of intracardiac mechanoreceptors and is mediated by vagal afferent nerve fibers. Several factors can sensitize the cardiovascular system to develop this reflex, including acute myocardial ischemia, natriuretic peptides, and, rarely, nitroglycerin administration in the setting of acute myocardial infarction. The development of the Bezold-Jarisch reflex in the presence of severe coronary artery stenosis, specifically left main coronary artery stenosis, has not been described. We report 2 cases of patients who underwent elective coronary angiography and were given intra-arterial nitroglycerin during radial sheath insertion to reduce radial artery spasm. In both patients, bradycardia and hypotension developed along with diaphoresis, consistent with the Bezold-Jarisch reflex. Coronary angiography revealed critical (>90%) left main coronary artery stenosis in both patients. Critical left main coronary artery stenosis might sensitize mechanoreceptors or vagal afferents to the development of the Bezold-Jarisch reflex after intra-arterial nitroglycerin use; however, the mechanism of this possible relationship is unclear. In addition to discussing our patients' cases, we review the medical literature relevant to the Bezold-Jarisch reflex.

Robotic investigation on effect of stretch reflex and crossed inhibitory response on bipedal hopping

PubMed Central

Rosendo, Andre; Ikemoto, Shuhei; Shimizu, Masahiro; Hosoda, Koh

2018-01-01

To maintain balance during dynamic locomotion, the effects of proprioceptive sensory feedback control (e.g. reflexive control) should not be ignored because of its simple sensation and fast reaction time. Scientists have identified the pathways of reflexes; however, it is difficult to investigate their effects during locomotion because locomotion is controlled by a complex neural system and current technology does not allow us to change the control pathways in living humans. To understand these effects, we construct a musculoskeletal bipedal robot, which has similar body structure and dynamics to those of a human. By conducting experiments on this robot, we investigate the effects of reflexes (stretch reflex and crossed inhibitory response) on posture during hopping, a simple and representative bouncing gait with complex dynamics. Through over 300 hopping trials, we confirm that both the stretch reflex and crossed response can contribute to reducing the lateral inclination during hopping. These reflexive pathways do not use any prior knowledge of the dynamic information of the body such as its inclination. Beyond improving the understanding of the human neural system, this study provides roboticists with biomimetic ideas for robot locomotion control. PMID:29593088

On Paper, on Air, on Screen: "Teledidactics" and Education at the Margins, 1920-1950

ERIC Educational Resources Information Center

Symes, Colin

2010-01-01

In this paper, I examine the provenance of distance education or "teledidactics" in Australia. I take as my case studies the New South Wales Correspondence School and the School of the Air and suggest that their emergence was underpinned by a desire on the part of educational and broadcasting bureaucrats to increase the equity of school…

Anatomical recommendations for safe botulinum toxin injection into temporalis muscle: a simplified reproducible approach.

PubMed

Lee, Won-Kang; Bae, Jung-Hee; Hu, Kyung-Seok; Kato, Takafumi; Kim, Seong-Taek

2017-03-01

The objective of this study was to simplify the anatomically safe and reproducible approach for BoNT injection and to generate a detailed topographic map of the important anatomical structures of the temporal region by dividing the temporalis into nine equally sized compartments. Nineteen sides of temporalis muscle were used. The topographies of the superficial temporal artery, middle temporal vein, temporalis tendon, and the temporalis muscle were evaluated. Also evaluated was the postural relations among the foregoing anatomical structures in the temporalis muscle, pivoted upon a total of nine compartments. The temporalis above the zygomatic arch exhibited an oblique quadrangular shape with rounded upper right and left corners. The distance between the anterior and posterior margins of the temporalis muscle was equal to the width of the temporalis rectangle, and the distance between the reference line and the superior temporalis margin was equal to its height. The mean ratio of width to height was 5:4. We recommend compartments Am, Mu, and Pm (coordinates of the rectangular outline) as areas in the temporal region for BoNT injection, because using these sites will avoid large blood vessels and tendons, thus improving the safety and reproducibility of the injection.

Posterior Bilateral Intermuscular Approach for Upper Cervical Spine Injuries.

PubMed

Xu, Yong; Xiong, Wei; Han, Sung I I; Fang, Zhong; Li, Feng

2017-08-01

To investigate a novel intermuscular surgical approach for posterior upper cervical spine fixation. Twenty-three healthy volunteers underwent magnetic resonance imaging. By using the magnetic resonance imaging scans in transverse view at the level of lower edge of atlas, the distances from the posterior midline to lateral margin of trapezius, to the medial margin of splenius capitis, and to middle line of semispinalis capitis were recorded. The angle between posterior middle line and the line crossing the lateral margin of trapezius and middle point of ipsilateral pedicles. From October 2009 to May 2013, 12 patients with upper cervical spine injuries were operated via the bilateral intermuscular approach. The time required for surgery, blood loss, and pre- and postoperative visual analogue scale scores were analyzed. The average distance of 0-T was 39.2 ± 7.5 mm, the angle between the approach and posterior middle line was 33.2 ± 8.4°. The surgical time was 78.3 ± 22.5 minutes (45-140 minutes), and the mean intraoperative blood loss was 87.5 ± 44.2 mL (30-200 mL). Preoperative and postoperative visual analogue scale scores were 6.4 ± 0.8 and 1.8 ± 0.7, respectively. The average follow-up time was 19.7 ± 11.5 months (9-48 months). The posterior bilateral intermuscular approach for upper cervical spine injuries is a valid alternative for Hangmans' fractures type I, type II, and type Ia according to Levine and Edwards classification as well as atlantoaxial subluxation caused by upper cervical spine trauma. Copyright © 2017 Elsevier Inc. All rights reserved.

Lateral spread of heat during thyroidectomy using different haemostatic devices.

PubMed

Adamczewski, Zbigniew; Król, Aleksander; Kałużna-Markowska, Karolina; Brzeziński, Jan; Lewiński, Andrzej; Dedecjus, Marek

2015-01-01

The presented study is an attempt to comprehensively analyze the lateral spread of heat during thyroidectomy. Obtained results may be valuable in other surgical disciplines in which thermal analysis is difficult or impossible. The aim of the study was to evaluate the temperature distribution in the operating field during thyroidectomy performed with the use of modern haemostatic instruments, and to define the safety margin for the investigated devices. Ninety-three patients were thyroidectomised due to thyroid neoplasm. During all the operations the thermovisual measurements were carried out along with continuous intraoperative neuromonitoring of the recurrent laryngeal nerve (CIONM). Investigated patients were divided into 5 groups, named according to the applied haemostatic technique: LigaSure (N=17); ThermoStapler (N=20); Focus (N=19); SonoSurg (N=17) and Monopolar (N=20). At maximal performance settings, the highest working temperature was observed for the ThermoStapler, while the lowest temperature was recorded for the Monopolar. Safety margin and working time were increased in Focus and SonoSurg, compared to LigaSure and ThermoStapler. The differences in the necrosis thickness were negligible. The largest distance of the midline of the active blade from isotherm of 42ºC observed in the study was 5.51 mm; none of investigated devices used at a bigger distance had influence on the morphology of the electric signal of CIONM. The thermo-visual camera allows non-invasive, safe, and real-time monitoring and analysis of temperature distribution in the operation area during thyroidectomy. Proposed minimal safety margin for the analysed devices is 5.51 mm.

Effectiveness of navigation-guided cyst aspiration before resection of large cystic brain tumors: a proof of concept for more radical surgery.

PubMed

Roh, Tae Hoon; Sung, Kyoung Su; Kang, Seok-Gu; Moon, Ju Hyung; Kim, Eui Hyun; Kim, Sun Ho; Chang, Jong Hee

2017-10-01

Resection of tumors close to the corticospinal tract (CST) carries a high risk of damage to the CST. For cystic tumors, aspirating the cyst before resection may reduce the risk of damage to vital structures. This study evaluated the effectiveness of cyst aspiration, by comparing the results before and after aspiration of diffusion tensor image (DTI) tractography. This study enrolled 23 patients with large cystic brain tumors (>20 cm 3 ) between 2012 and 2016. All underwent magnetic resonance imaging (MRI), including DTI tractography, followed by navigation-guided aspiration of the cyst and subsequent tumor resection via craniotomy. Distances between the tumor margin and CST before and after cyst aspiration, volume reduction, and postoperative outcomes were assessed. Median tumor volume decreased from 88 cm 3 (range, 25-153) to 29 cm 3 (range, 20-80) and distances between tumor margins and the CST increased from 5.7 mm (range, 0.6-22.0) to 14.8 mm (range, 0.6-41.4) after aspiration. Neurological symptoms of patients immediately improved after cyst aspiration. All patients, except for one with a secondary glioblastoma, underwent gross total resection of the tumor. No neurological deterioration was observed after tumor resection. Navigation-guided cyst aspiration followed by resection is a useful and safe procedure for brain tumors with large cystic components. Cyst aspiration resulted in expansion of the compressed brain tissue between the tumor margins and vital structures, making maximal safe resection possible.

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

PubMed Central

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

The cremasteric reflex and its muscle - a paragon of ongoing scientific discussion: A systematic review.

PubMed

Schwarz, Gilbert M; Hirtler, Lena

2017-05-01

The technique of triggering the cremasteric reflex and its respective signaling pathway is not described uniformly throughout the literature. As this reflex is a useful sign in diagnosing testicular torsion, orchitis, varicocele, and undescended testis, it seems desirable to identify and define the correct mechanism. Our aim was to investigate how the cremasteric reflex and its signaling pathway are described in the current literature and how the variability of the innervation of the inguinal region could affect the frequency of this reflex. Thirty-five original articles and 18 current textbooks were included after searching PubMed (MEDLINE) and Scopus for the terms "cremaster muscle," "cremasteric reflex," and "genitofemoral nerve" and after applying all exclusion criteria. This systematic review was performed according to the PRISMA Statement Rules. Eliciting the cremasteric reflex was defined either as "rubbing of the upper inner thigh" or "rubbing of the skin under the inguinal ligament." Four different afferent pathways among studies and three different pathways among textbooks were described and the frequency of an intact reflex ranged between 42.7 and 92.5% in newborns and between 61.7 and 100% in boys between 24 months and 12 years. Owing to the huge differences among the studies investigated and the lack of convincing results, it is not possible to define the correct way to elicit the cremasteric reflex. Four hypotheses about the afferent pathway are proposed on the basis of the literature. Further studies should be performed, concentrating on the afferent pathway(s) with respect to the individual innervation of the inguinal region. Clin. Anat. 30:498-507, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Effect of pinching-evoked pain on jaw-stretch reflexes and exteroceptive suppression periods in healthy subjects.

PubMed

Biasiotta, A; Peddireddy, A; Wang, K; Romaniello, A; Frati, A; Svensson, P; Arendt-Nielsen, L

2007-10-01

To investigate the influence of conditioning cutaneous nociceptive inputs by a new "pinch" model on the jaw-stretch reflex and the exteroceptive suppression periods (ES1 and ES2) in jaw muscles. The jaw-stretch reflex was evoked with the use of a custom-made muscle stretcher and electrical stimuli were used to evoke an early and late exteroceptive suppression period (ES1 and ES2) in the jaw-closing muscles. Electromyographic (EMG) activity was recorded bilaterally from the masseter and temporalis muscles. These brainstem reflexes were recorded in 19 healthy men (28.8+/-1.1 years) during three different conditions: one painful clip applied to the earlobe; one painful clip applied to the nostril, and four painful clips applied simultaneously to the earlobe, nostril, eyebrow, and lower lip. Pain intensity induced by the application of the clips was scored continuously by the subjects on a 100mm visual analogue scale (VAS). The highest VAS pain scores were evoked by placement of four clips (79+/-0.5mm). There was no significant modulation of the jaw-stretch reflex (ANOVAs: P=0.929), the ES1 (P=0.298) or ES2 (P=0.082) in any of the three painful conditions. Intense and tonic cutaneous pain could be elicited by this new "pinch" pain model; however, there was no significant modulation on either excitatory or inhibitory brainstem reflex responses. The novel observation that high-intensity pinch stimuli applied to the craniofacial region fail to modulate two different brainstem reflexes is in contrast to other experimental pain studies documented facilitation of the jaw-stretch reflexes or inhibition of exteroceptive suppression periods. The clinical implication of the present findings is that only some craniofacial pain conditions could be expected to show perturbation of the brainstem reflex responses.

Does spasticity contribute to walking dysfunction after stroke?

PubMed Central

Ada, L.; Vattanasilp, W.; O'Dwyer, N.; Crosbie, J.

1998-01-01

OBJECTIVES—Clinically, it is assumed that spasticity of the calf muscles interferes with walking after stroke. The aim was to examine this assumption by evaluating the contribution of spasticity in the gastrocnemius muscle to walking dysfunction in an ambulant stroke population several months after stroke.
METHODS—Fourteen stroke patients who were able to walk independently and 15 neurologically normal control subjects were recruited. Both resting and action stretch reflexes of the gastrocnemius muscle were investigated under conditions that simulated walking. Resting tonic stretch reflexes were measured to assess spasticity whereas action tonic stretch reflexes were measured to assess the possible contribution of spasticity to gait dysfunction.
RESULTS—Two thirds of the stroke patients exhibited resting tonic stretch reflexes which indicate spasticity, whereas none of the control subjects did. However, the stroke patients exhibited action tonic stretch reflexes that were of similar magnitude to the control subjects, suggesting that their reflex activity during walking was not different from that of control subjects. Furthermore, there was no evidence that the action stretch reflex in the stroke patients contributed a higher resistance to stretch than the control subjects.
CONCLUSIONS—Whereas most of the stroke patients exhibited spasticity when measured both clinically and physiologically, they did not exhibit an increase in resistance to dorsiflexion due to exaggerated action tonic stretch reflexes. It is concluded that it is unlikely that spasticity causes problems in walking after stroke in ambulant patients. Therefore, it seems inappropriate to routinely reduce or inhibit the reflex response to improve functional movement in stroke rehabilitation. Factors other than spasticity should be considered when analysing walking after stroke, so that appropriate treatment is provided to patients.

 PMID:9598679

Testing rocuronium-induced neuromuscular blockade at the stapedius muscle using stapedius reflex measurements.

PubMed

Sárkány, P; Tassonyi, E; Nemes, R; Timkó, A; Pongrácz, A; Fülesdi, Béla

2011-12-01

Neuromuscular monitoring prior to emergence from anaesthesia has been shown to be necessary to achieve adequate airway protection in order to decrease postoperative pulmonary complications. In the present study we hypothesized that stapedius reflex measurement allows the detection of residual neuromuscular blockade using the stapedius muscle following the administration of rocuronium. Parallel stapedius and acceleromyographic measurements were performed on 20 patients undergoing cholecystectomy. Acceleromyographic measurements were continuously performed during the course of anaesthesia, whereas the stapedius reflex was measured on different occasions: (1) after premedication but before anaesthesia induction, (2) after induction, but before administration of muscle relaxant, (3) after administration of muscle relaxant, (4) during the course of surgical anaesthesia at regular intervals, and (5) continuously performed during emergence from anaesthesia, until the stapedius reflex threshold returned to normal. The intensity of the sound energy at which the stapedius reflex is detectable was similar: 89.5 ± 9.9 dB(mean ± SD) after premedication and after anaesthetic induction. However, after administration of rocuronium, when the twitch height decreased to 5%, the stapedius reflex disappeared, indicating a total block of the stapedius muscle.During the recovery phase (twitch>10%) significantly higher sound energies compared to baseline values were necessary to evoke the reflex, indicating residual inhibition of the stapedius muscle. At the point where stapedius reflex threshold returned to normal the twitch height averaged about 50% showing low sensitivity of the tympanometry in detecting residual neuromuscular blockade. The neuromuscular effect of rocuronium on the stapedius muscle can be detected using stapedius reflex measurements. Due to its methodological limitation and low sensitivity, the method cannot be recommended for the monitoring of residual neuromuscular blockade.

Reflex regulation during sustained and intermittent submaximal contractions in humans

PubMed Central

Duchateau, Jacques; Balestra, Costantino; Carpentier, Alain; Hainaut, Karl

2002-01-01

To investigate whether the intensity and duration of a sustained contraction influences reflex regulation, we compared sustained fatiguing contractions at 25 % and 50 % of maximal voluntary contraction (MVC) force in the human abductor pollicis brevis (APB) muscle. Because the activation of motoneurones during fatigue may be reflexively controlled by the metabolic status of the muscle, we also compared reflex activities during sustained and intermittent (6 s contraction, 4 s rest) contractions at 25 % MVC for an identical duration. The short-latency Hoffmann(H) reflex and the long-latency reflex (LLR) were recorded during voluntary contractions, before, during and after the fatigue tests, with each response normalised to the compound muscle action potential (M-wave). The results showed that fatigue during sustained contractions was inversely related to the intensity, and hence the duration, of the effort. The MVC force and associated surface electromyogram (EMG) declined by 26.2 % and 35.2 %, respectively, after the sustained contraction at 50 % MVC, and by 34.2 % and 44.2 % after the sustained contraction at 25 % MVC. Although the average EMG increased progressively with time during the two sustained fatiguing contractions, the amplitudes of the H and LLR reflexes decreased significantly. Combined with previous data (Duchateau & Hainaut, 1993), the results show that the effect on the H reflex is independent of the intensity of the sustained contraction, whereas the decline in the LLR is closely related to the duration of the contraction. Because there were no changes in the intermittent test at 25 % MVC, the results indicate that the net excitatory spinal and supraspinal reflex-mediated input to the motoneurone pool is reduced. This decline in excitation to the motoneurones, however, can be temporarily compensated by an enhancement of the central drive. PMID:12068054

Roles of neuronal NK1 and NK3 receptors in synaptic transmission during motility reflexes in the guinea-pig ileum

PubMed Central

Johnson, P J; Bornstein, J C; Burcher, E

1998-01-01

The role of NK1 and NK3 receptors in synaptic transmission between myenteric neurons during motility reflexes in the guinea-pig ileum was investigated by recording intracellularly the reflex responses of the circular muscle to distension or compression of the mucosal villi. Experiments were performed in a three-chambered organ bath that enabled drugs to be selectively applied to different sites along the reflex pathways.When applied in the recording chamber, an NK1 receptor antagonist, SR140333 (100 nM), reduced by 40–50% the amplitudes of inhibitory junction potentials (i.j.ps) evoked in the circular muscle by activation of descending reflex pathways. This effect was abolished when synaptic transmission in the stimulus region was blocked with physiological saline containing 0.1 mM Ca2+ plus 10 mM Mg2+, leaving only the component of the descending reflex pathway conducted via long anally directed collaterals of intrinsic sensory neurons.SR140333 (100 nM) had no effect on descending reflex i.j.ps when applied to the stimulus region. Ascending reflexes were also unaffected by SR140333 in the stimulus region or between the stimulus and recording sites.Septide (10 nM), an NK1 receptor agonist, enhanced descending reflexes by 30–60% when in the recording chamber. [Sar9,Met(O2)11]substance P had no effect at 10 nM, but potentiated distension-evoked reflexes at 100 nM.A selective NK3 receptor antagonist, SR142801 (100 nM), when applied to the stimulus region, reduced the amplitude of descending reflex responses to compression by 40%, but had no effect on responses to distension. SR142801 (100 nM) had no effect when applied to other regions of the descending reflex pathways.SR142801 (100 nM) only inhibited ascending reflexes when applied at the recording site. However, after nicotinic transmission in the stimulus region was blocked, SR142801 (100 nM) at this site reduced responses to compression.Contractions of the circular muscle of isolated rings of ileum evoked by low concentrations of septide, but not [Sar9,Met(O2)11]substance P, were potentiated by tetrodotoxin (300 nM).Contractile responses evoked by an NK3 receptor agonist, senktide, were non-competitively inhibited by SR142801. After excitatory neuromuscular transmission was blocked, senktide produced inhibitory responses that were also antagonised by SR142801, but to a lesser extent and in an apparently competitive manner.These results indicate that tachykinins acting via NK1 receptors partly mediate transmission to inhibitory motor neurons. NK3 receptors play a role in transmission from intrinsic sensory neurons and from ascending interneurons to excitatory motor neurons during motility reflexes. PMID:9723948

The legacy of care as reflexive learning

PubMed Central

García, Marta Rodríguez; Moya, Jose Luis Medina

2016-01-01

Abstract Objective: 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. Method: 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. Results: 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. Conclusions: reflexive practice is key to tutors' training and students' learning. PMID:27305180

Reconsidering reflexivity: introducing the case for intellectual entrepreneurship.

PubMed

Cutcliffe, John R

2003-01-01

In this article, the author reconsiders reflexivity and attempts to examine some unresolved issues by drawing particular attention to the relationship between reflexivity and certain related phenomena/processes: the researcher's a priori knowledge, values, beliefs; empathy within qualitative research; the presence and influence of the researcher's tacit knowledge, and May's "magic" in method. Given the limitations of some reflexive activity identified in this article, the author introduces the case for greater intellectual entrepreneurship within the context of qualitative research. He suggests that excessive emphasis on reflexive activity might inhibit intellectual entrepreneurship. Wherein intellectual entrepreneurship implies a conscious and deliberate attempt on the part of academics to explore the world of ideas boldly; to take more risks in theory development and to move away from being timid researchers.

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

PubMed Central

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

THE EFFECT OF PENETRATING RADIATION ON THE REFLEXES FROM INTESTINAL RECEPTORS (in Russian)

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

Dzharakyan, T.K.; Fakhrutdinov, G.F.

1958-03-01

The reflexes from the chemo-, baro-, and thermoceptors of the small intestine were studied in acute and chronic experiments on dogs after the general action of penetrating radiation (400 r). Regular changes were revealed in the reflexes. They consisted of an increase of the vegetative components (vascular- motor, cardiac, and respiratory) and other components (movement of the head and the body) of the reflex reaction in response to the action of the stimulants of the threshold value, as well as in considerable increase of the consequent period. The changes in the reflexes appear on the 6th to 10th day aftermore » the actwon of penetrating radiation and increase with development of this disease. The intensity of these changes depend on the gravity of the radiation sickness. In the authors' opinion the changes in the reflexes are due to disturbance of the functional condition of the subcortical ganglia of the central nervous system. (tr-auth)« less

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

PubMed

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.

Johnson square procedure for lentigo maligna and lentigo maligna melanoma.

PubMed

Patel, A N; Perkins, W; Leach, I H; Varma, S

2014-07-01

Lentigo maligna (LM) and lentigo maligna melanoma (LMM) can be difficult to manage surgically. Predetermined margins can be inadequate because of subclinical spread, or can affect function when margins are adjacent to the eye or mouth. To describe our 5-year experience in Nottingham of using the staged square procedure (Johnson square) in excising difficult facial LM and LMM. The square procedure is a staged technique useful for ill-defined lesions and for lesions that have a high recurrence rate due to subclinical spread. It uses paraffin wax-embedded peripheral vertical sections for margin control, ensuring complete clearance as the surgical margins are usually examined at distances of 2-5 mm from the periphery of the lesion. We treated 21 patients with LM or LMM with the staged square procedure over a 5-year period. Of the 21 patients, 10 needed only one stage of surgery, 6 needed two stages, 3 needed three stages and 2 needed four stages. To date, there has been only one recurrence, which was of an extensive lesion that crossed the medial canthus, making margin control impossible because of the anatomical limitations. The staged square procedure is an effective treatment for LM and LMM. It attempts to conserve tissue while ensuring a higher clearance rate. This offers favourable cosmetic outcomes and better prognosis, especially for facial LM and LMM. © 2014 British Association of Dermatologists.

Corrosion behavior and microhardness of three amalgams.

PubMed

Patsurakos, A; Moberg, L E

1988-08-01

The marginal microhardness of three different types of amalgam was tested after 2 months' immersion in an aqueous solution of NaCl (85 mM) and phosphates (Na2HPO4 100 mM and NaH2PO4 100 mM). Amalgams immersed in distilled water were used as controls. The microhardness tests were conducted at a distance of 50 micron from the margins and at the bulk of each specimen. The solutions were analyzed for Sn, Cu, Zn, Ag, and Hg by means of atomic absorption spectrophotometry (AAS). A statistically significant reduction in the marginal microhardness after immersion in the test solution was found for the conventional and the high-Cu single composition amalgam but not for the high-Cu blended amalgam. SEM-examination of cross-sections of the amalgams revealed small areas of subsurface grain boundary corrosion, no deeper than 10 micron for all the amalgams. The SEM-examination of the specimens and AAS analysis of the solutions indicated that the reduction in marginal microhardness was attributed mainly to corrosion of the Cu-rich phases for the high-Cu single composition amalgam and to corrosion of the gamma 2 phase for the conventional amalgam. The phosphates reduced the corrosion of the amalgams in the presence of NaCl. It is concluded that the marginal strength of dental amalgams in a corrosive environment is largely dependent upon their corrosion resistance.

Crustal geometry of the northeastern Gulf of Aden passive margin: localization of the deformation inferred from receiver function analysis

NASA Astrophysics Data System (ADS)

Tiberi, C.; Leroy, S.; d'Acremont, E.; Bellahsen, N.; Ebinger, C.; Al-Lazki, A.; Pointu, A.

2007-03-01

Here we use receiver function analysis to retrieve crustal thickness and crustal composition along the 35-My-old passive margin of the eastern Gulf of Aden. Our aims are to use results from the 3-D seismic array to map crustal stretching across and along the Aden margin in southern Oman. The array recorded local and teleseismic events between 2003 March and 2004 March. Seventy-eight events were used in our joint inversions for Vp/Vs ratio and depth. The major results are: (1) Crustal thickness decreases from the uplifted rift flank of the margin towards the Sheba mid-ocean ridge. We found a crustal thickness of about 35 km beneath the northern rift flank. This value decreases sharply to 26 km beneath the post-rift subsidence zone on the Salalah coastal plain. This 10 km of crustal thinning occurs across a horizontal distance of less than 30 km showing a localization of the crustal thinning below the first known rifted block of the margin. (2) A second rift margin transect located about 50 km to the east shows no thinning from the coast to 50 km onshore. The lack of crustal thickness variation indicates that the maximum crustal stretching could be restricted to offshore regions. (3) The along-strike variations in crustal structure demonstrate the scale and longevity of the regular along-axis rift segmentation. (4) Extension is still observed north of the rifted domain, 70 km onshore from the coast, making the width of margin larger than first expected from geology. (5) The crust has a felsic to normal composition with a probably strong effect of the sedimentary layer on the Vp/Vs ratio (comprised between 1.67 and 1.91).

Are the unken reflex and the aposematic colouration of Red-Bellied Toads efficient against bird predation?

PubMed Central

Caorsi, Valentina Zaffaroni; Colombo, Patrick; Abadie, Michelle; Brack, Ismael Verrastro; Dasoler, Bibiana Terra; Borges-Martins, Márcio

2018-01-01

Aposematic signals as well as body behaviours may be important anti-predator defences. Species of the genus Melanophryniscus are characterised by having toxic lipophilic alkaloids in the skin and for presenting a red ventral colouration, which can be observed when they perform the behaviour called the unken reflex. Both the reflex behaviour and the colouration pattern are described as defence mechanisms. However, there are currently no studies testing their effectiveness against predators. This study aimed to test experimentally if both ventral conspicuous colouration and the unken reflex in Melanophryniscus cambaraensis function as aposematic signals against visually oriented predators (birds). We simulated the species studied using three different clay toad models as follows: (a) in a normal position with green coloured bodies, (b) in the unken reflex position with green coloured body and extremities and (c) in the unken reflex position with a green body and red extremities. Models were distributed on a known M. cambaraensis breeding site and in the adjacent forest. More than half of the attacks on the models were from birds; however, there was no preference for any model type. Thus, just the presence of the red colour associated with the motionless unken reflex position does not seem to prevent attacks from potential predators. It is possible that the effective aposematic signal in Melanophryniscus is achieved through the unken reflex movement together with the subsequent exhibition of the warning colouration and the secretion of toxins. PMID:29596437

Neural effects of muscle stretching on the spinal reflexes in multiple lower-limb muscles.

PubMed

Masugi, Yohei; Obata, Hiroki; Inoue, Daisuke; Kawashima, Noritaka; Nakazawa, Kimitaka

2017-01-01

While previous studies have shown that muscle stretching suppresses monosynaptic spinal reflex excitability in stretched muscles, its effects on non-stretched muscles is still largely unknown. The purpose of this study was to examine the effects of muscle stretching on monosynaptic spinal reflex in non-stretched muscles. Ten healthy male subjects participated in this study. Muscle stretching of the right triceps surae muscle was performed using a motor torque device for 1 minute. Three different dorsiflexion torques (at approximately 5, 10, and 15 Nm) were applied during muscle stretching. Spinal reflexes evoked by transcutaneous spinal cord stimulation were recorded in both the lower-limb muscles before, during, and at 0 and 5 min following muscle stretching. The amplitudes of the spinal reflexes in both the stretched and non-stretched muscles in the right (ipsilateral) leg were smaller during stretching compared to before, and at 0 and 5 min after stretching. Furthermore, the degree of reduction in the amplitude of the spinal reflexes in the right (ipsilateral) leg muscles increased significantly as the dorsiflexion torque (i.e., stretching of the right triceps surae muscles) increased. In contrast, reduction in the amplitude of the spinal reflexes with increasing dorsiflexion torque was not seen in the left (contralateral) leg muscles. Our results clearly indicate that muscle stretching has inhibitory effects on monosynaptic spinal reflexes, not only in stretched muscles, but also in non-stretched muscles of the ipsilateral leg.

Neural effects of muscle stretching on the spinal reflexes in multiple lower-limb muscles

PubMed Central

Obata, Hiroki; Inoue, Daisuke; Kawashima, Noritaka; Nakazawa, Kimitaka

2017-01-01

While previous studies have shown that muscle stretching suppresses monosynaptic spinal reflex excitability in stretched muscles, its effects on non-stretched muscles is still largely unknown. The purpose of this study was to examine the effects of muscle stretching on monosynaptic spinal reflex in non-stretched muscles. Ten healthy male subjects participated in this study. Muscle stretching of the right triceps surae muscle was performed using a motor torque device for 1 minute. Three different dorsiflexion torques (at approximately 5, 10, and 15 Nm) were applied during muscle stretching. Spinal reflexes evoked by transcutaneous spinal cord stimulation were recorded in both the lower-limb muscles before, during, and at 0 and 5 min following muscle stretching. The amplitudes of the spinal reflexes in both the stretched and non-stretched muscles in the right (ipsilateral) leg were smaller during stretching compared to before, and at 0 and 5 min after stretching. Furthermore, the degree of reduction in the amplitude of the spinal reflexes in the right (ipsilateral) leg muscles increased significantly as the dorsiflexion torque (i.e., stretching of the right triceps surae muscles) increased. In contrast, reduction in the amplitude of the spinal reflexes with increasing dorsiflexion torque was not seen in the left (contralateral) leg muscles. Our results clearly indicate that muscle stretching has inhibitory effects on monosynaptic spinal reflexes, not only in stretched muscles, but also in non-stretched muscles of the ipsilateral leg. PMID:28662201

Effects of postural and voluntary muscle contraction on modulation of the soleus H reflex by transcranial magnetic stimulation.

PubMed

Guzmán-López, Jessica; Selvi, Aikaterini; Solà-Valls, Núria; Casanova-Molla, Jordi; Valls-Solé, Josep

2015-12-01

Modulation of spinal reflexes depends largely on the integrity of the corticospinal tract. A useful method to document the influence of descending tracts on reflexes is to examine the effects of transcranial magnetic stimulation (TMS) on the soleus H reflex elicited by posterior tibial nerve electrical stimuli (PTS). In 12 healthy volunteers, we investigated how postural or voluntary muscle contraction modified such descending modulation. We first characterized the effects of TMS at 95 % of motor threshold for leg responses on the H reflex elicited by a preceding PTS at inter-stimuli intervals (ISIs) between 0 and 120 ms at rest and, then, during voluntary plantar flexion (pf), dorsal flexion (df), and standing still (ss). During pf, there was an increase in the facilitation of the H reflex at ISIs 0-20 ms. During df, there were no effects of TMS on the H reflex. During ss, there was inhibition at ISIs 40-60 ms. Our observations suggest that muscle contraction prevails over the baseline effects of TMS on the soleus H reflex. While contraction of the antagonist (df) suppressed most of the effects, contraction of the agonist had different effects depending on the type of activity (pf or ss). The characterization of the interaction between descending corticospinal volleys and segmental peripheral inputs provides useful information on motor control for physiological research and further understanding of the effects of spinal cord lesions.

Control of aperture closure initiation during reach-to-grasp movements under manipulations of visual feedback and trunk involvement in Parkinson's disease.

PubMed

Rand, Miya Kato; Lemay, Martin; Squire, Linda M; Shimansky, Yury P; Stelmach, George E

2010-03-01

The present project was aimed at investigating how two distinct and important difficulties (coordination difficulty and pronounced dependency on visual feedback) in Parkinson's disease (PD) affect each other for the coordination between hand transport toward an object and the initiation of finger closure during reach-to-grasp movement. Subjects with PD and age-matched healthy subjects made reach-to-grasp movements to a dowel under conditions in which the target object and/or the hand were either visible or not visible. The involvement of the trunk in task performance was manipulated by positioning the target object within or beyond the participant's outstretched arm to evaluate the effects of increasing the complexity of intersegmental coordination under different conditions related to the availability of visual feedback in subjects with PD. General kinematic characteristics of the reach-to-grasp movements of the subjects with PD were altered substantially by the removal of target object visibility. Compared with the controls, the subjects with PD considerably lengthened transport time, especially during the aperture closure period, and decreased peak velocity of wrist and trunk movement without target object visibility. Most of these differences were accentuated when the trunk was involved. In contrast, these kinematic parameters did not change depending on the visibility of the hand for both groups. The transport-aperture coordination was assessed in terms of the control law according to which the initiation of aperture closure during the reach occurred when the hand distance-to-target crossed a hand-target distance threshold for grasp initiation that is a function of peak aperture, hand velocity and acceleration, trunk velocity and acceleration, and trunk-target distance at the time of aperture closure initiation. When the hand or the target object was not visible, both groups increased the hand-target distance threshold for grasp initiation compared to its value under full visibility, implying an increase in the hand-target distance-related safety margin for grasping. The increase in the safety margin due to the absence of target object vision or the absence of hand vision was accentuated in the subjects with PD compared to that in the controls. The pronounced increase in the safety margin due to absence of target object vision for the subjects with PD was further accentuated when the trunk was involved compared to when it was not involved. The results imply that individuals with PD have significant limitations regarding neural computations required for efficient utilization of internal representations of target object location and hand motion as well as proprioceptive information about the hand to compensate for the lack of visual information during the performance of complex multisegment movements.

Diameters of the cavo-sinus-tricuspid area in relation to type I atrial flutter.

PubMed

Kozłowski, Dariusz; Hreczecha, Jolanta; Skwarek, Magdalena; Piwko, Grzegorz; Kosiński, Adam; Gawrysiak, Marcin; Grzybiak, Marek

2003-05-01

Cardiac arrhythmias have troubled patients and fascinated physicians for centuries. The twentieth century was an era of progress, when the mechanism of cardiac disorders became more commonly recognised. Arrhythmias may be due to abnormalities of automaticity, to abnormalities of conduction, or to a combination of both. In order for re-entry to occur, an area of slowing conduction combined with unidirectional block must be present. Much investigation has centred on the underlying re-entry mechanisms of atrial flutter. In the light of these facts, it would seem that a close acquaintance with the detailed topography of the vena cava orifice (cavo), coronary sinus orifice (sinus) and the attachment of the septal leaflet of the tricuspid valve (tricupid) area could be of great interest, especially for invasive cardiologists. The research was conducted carried out on material consisting of 41 hearts of humans of both sexes from the age of 12 to 80 (6 female, 35 male). Classical macroscopic methods of anatomical evaluation were used. The following measurements were made: the shortest distance between the Eustachian valve and the attachment of the tricuspid valve on the left margin of the coronary sinus orifice (diameter 1), the distance between the attachment of the tricuspid valve and the inferior margin of the sinus orifice (diameter 2), the distance between the Eustachian valve and the attachment of the tricuspid valve on the right margin of the coronary sinus orifice (diameter 3), the distance between the inferior margin of the vena cava inferior and the attachment of the tricuspid valve (diameter 4) and, finally, the diameter between the attachment of the septal cusp of the tricuspid valve and the extemal border of the vena cava inferior (diameter 5). No correlation was found between the age and sex of the three groups of the material. The dimensions of the structure examined were similar in the three groups of hearts. In young adult hearts all the diameters measured ranged from 4 to 47 mm. The average diameters were, respectively: 15.02 mm (diameter 1), 8.97 mm (diameter 2), 17.27 mm (diameter 3), 26.87 mm (diameter 4), 36.42 mm (diameter 5). In the mature adult hearts all the diameters measured ranged from 8 to 45 mm; 18.19 mm (diameter 1), 10.54 mm (diameter 2), 19.95 mm (diameter 3), 28.90 mm (diameter 4), 39.63 mm (diameter 5). In the older adults hearts all the diameters measured ranged from 4 to 47 mm. The average diameters were, respectively: 15.65 mm (diameter 1), 8.70 mm (diameter 2), 7.25 mm (diameter 3), 26.80 mm (diameter 4), 35.85 mm (diameter 5). On the basis of our study we were able to conclude that the diameters of the cavo-sinus-tricuspid area were constant and did not differ significantly within the three (young, mature, old) adult groups examined.

The Dynamics of Successive Induction in Larval Zebrafish

ERIC Educational Resources Information Center

Staddon, J. E. R.; MacPhail, R. C.; Padilla, S.

2010-01-01

Charles Sherrington identified the properties of the synapse by purely behavioral means--the study of reflexes--more than 100 years ago. They were subsequently confirmed neurophysiologically. Studying reflex interaction, he also showed that activating one reflex often facilitates another, antagonistic one: "successive induction," which has since…

21 CFR 890.1450 - Powered reflex hammer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex...

21 CFR 890.1450 - Powered reflex hammer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex...

21 CFR 890.1450 - Powered reflex hammer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex...

21 CFR 890.1450 - Powered reflex hammer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Powered reflex hammer. 890.1450 Section 890.1450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex...

21 CFR 890.1450 - Powered reflex hammer.

Code of Federal Regulations, 2010 CFR

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) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1450 Powered reflex...

Age Related Decline in Postural Control Mechanisms.

ERIC Educational Resources Information Center

Stelmach, George E.; And Others

1989-01-01

Studied voluntary and reflexive mechanisms of postural control of young (N=8) and elderly (N=8) adults through measurement of reflexive reactions to large-fast and small-slow ankle rotation postural disturbances. Found reflexive mechanisms relatively intact for both groups although elderly appeared more disadvantaged when posture was under the…

Informed Reflexivity: Enacting Epistemic Virtue

ERIC Educational Resources Information Center

Weinstock, Michael; Kienhues, Dorothe; Feucht, Florian C.; Ryan, Mary

2017-01-01

To discuss reflexive practice in relation to epistemic cognition, we posit informed reflexivity as an epistemic virtue that is informed by its particular context and purposes of knowing and action and promotes use of reliable processes to achieve epistemic aims. It involves reasoning about social relationships in which a person is embedded when…

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

ERIC Educational Resources Information Center

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…

The Reflexive Imperative among High-Achieving Adolescents: A Flemish Case Study

ERIC Educational Resources Information Center

Van Lancker, Inge

2016-01-01

The socio-cultural conditions of late modernity induce a "reflexive imperative" amongst young people, which also results in metapragmatic and metalinguistic behaviour, as has been demonstrated by linguistic ethnographers (LE). However, recent LE studies on reflexivity in Western European settings have mainly focused on how groups of…

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

ERIC Educational Resources Information Center

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…

A modular telerobotic task execution system

NASA Technical Reports Server (NTRS)

Backes, Paul G.; Tso, Kam S.; Hayati, Samad; Lee, Thomas S.

1990-01-01

A telerobot task execution system is proposed to provide a general parametrizable task execution capability. The system includes communication with the calling system, e.g., a task planning system, and single- and dual-arm sensor-based task execution with monitoring and reflexing. A specific task is described by specifying the parameters to various available task execution modules including trajectory generation, compliance control, teleoperation, monitoring, and sensor fusion. Reflex action is achieved by finding the corresponding reflex action in a reflex table when an execution event has been detected with a monitor.

Role of the cerebellum and the vestibular apparatus in regulation of orthostatic reflexes in the cat

NASA Technical Reports Server (NTRS)

Doba, N.; Reis, D. J.

1974-01-01

The contribution of the fastigial nucleus and the vestibular nerves (eighth cranial nerves) to the orthostatic reflexes in anesthetized, paralyzed cats was studied. Bilateral lesions of the rostral fastigial nucleus resulted in impairment of the reflex changes in blood pressure, femoral arterial flow, and resistance evoked by head-up tilting to 30 deg or 60 deg. The rostral fastigial nucleus, which might be triggered by the vestibular apparatus, appears to participate in concert with the baroreceptors in the initiation and possibly the maintenance of the orthostatic reflexes.

[Facial diplegia with atypical paresthesia. A variant of Guillain-Barré syndrome].

PubMed

Dal Verme, Agustín; Acosta, Paula; Margan, Mercedes; Pagnini, Cecilia; Dellepiane, Eugenia; Peralta, Christian

2015-01-01

Guillain-Barré syndrome is an acute demyelinating disease which presents in a classic form with muscular weakness and the lack of reflexes. There are multiple variations and atypical forms of the disease, being facial diplegia with paresthesia one of them. Also, the absence of reflexes in this syndrome is typical but not constant, since 10% of patients present reflexes. We describe a case of atypical presentation with bilateral facial palsy, paresthesia, brisk reflexes and weakness in the lower limbs in a 33 year old woman.

Both Predator and Prey

PubMed Central

Löw, Andreas; Lang, Peter J.; Smith, J. Carson; Bradley, Margaret M.

2013-01-01

This research examined the psychophysiology of emotional arousal anticipatory to potentially aversive and highly pleasant outcomes. Human brain reactions (event-related potentials) and body reactions (heart rate, skin conductance, the probe startle reflex) were assessed along motivational gradients determined by apparent distance from sites of potential punishment or reward. A predator-prey survival context was simulated using cues that signaled possible money rewards or possible losses; the cues appeared to loom progressively closer to the viewer, until a final step when a rapid key response could ensure reward or avoid a punishing loss. The observed anticipatory response patterns of heightened vigilance and physiological mobilization are consistent with the view that the physiology of emotion is founded on action dispositions that evolved in mammals to facilitate survival by dealing with threats or capturing life-sustaining rewards. PMID:18947351

[Red reflex: prevention way to blindness in childhood].

PubMed

de Aguiar, Adriana Sousa Carvalho; Cardoso, Maria Vera Lúcia Moreira Leitão; Lúcio, Ingrid Martins Leite

2007-01-01

This study had as objective to investigate the result and the colour gradation of red reflex test in newborns (NB). It is a exploratory, quantitative study and the sample was 180 NB from maternity ward in Fortaleza-CE. From this, 156 showed result "no altered" and 24 "suspect". About the aspect of red reflex, 144 NB showed the same coloration in the two eyes, in 35 of this, the colour was red, in 33, orange reddish, in 46 orange colour, in 24 light yellow, in 6 yellow with whitish stains central. Of the suspect cases, the reflex was light yellow with whitish stains with lines. The nurse trained to accomplish the red reflex test can have important role at Neonatal Unit with actions about the prevention of ocular alterations in the childhood.

Tonic blood pressure modulates the relationship between baroreceptor cardiac reflex sensitivity and cognitive performance.

PubMed

Del Paso, Gustavo A Reyes; González, M Isabel; Hernández, José Antonio; Duschek, Stefan; Gutiérrez, Nicolás

2009-09-01

This study explored the effects of tonic blood pressure on the association between baroreceptor cardiac reflex sensitivity and cognitive performance. Sixty female participants completed a mental arithmetic task. Baroreceptor reflex sensitivity was assessed using sequence analysis. An interaction was found, indicating that the relationship between baroreceptor reflex sensitivity and cognitive performance is modulated by blood pressure levels. Reflex sensitivity was inversely associated to performance indices in the subgroup of participants with systolic blood pressure above the mean, whereas the association was positive in participants with systolic values below the mean. These results are in accordance with the findings in the field of pain perception and suggest that tonic blood pressure modulates the inhibitory effects of baroreceptor stimulation on high central nervous functions.

Management of exaggerated gag reflex in dental patients using intravenous sedation with dexmedetomidine.

PubMed

Reshetnikov, Aleksei P; Kasatkin, Anton A; Urakov, Aleksandr L; Baimurzin, Dmitrii Y

2017-01-01

Pharmacological sedation is one of the effective ways of prevention of gag reflex development in patients experiencing anxiety and fright before dental treatment. We are reporting a case where we could successfully eliminate exaggerated gag reflex (intravenous [IV] Gagging Severity Index) in a dental patient using IV sedation with dexmedetomidine. IV administration of dexmedetomidine provided elimination of gag reflex at a depth of sedation for the patient with the Richmond Agitation-Sedation Scale score of -2 and -1. The patient received dexmedetomidine 1.0 μg/kg for 10 min and then a continuous infusion of dexmedetomidine 0.4 μg/kg/h. The use of dexmedetomidine for sedation may be an alternative to other pharmacological agents in patients with dental anxiety accompanied by exaggerated gag reflex.

Time course of the soleus M response and H reflex after lidocaine tibial nerve block in the rat.

PubMed

Buffenoir, Kévin; Decq, Philippe; Pérot, Chantal

2013-01-01

In spastic subjects, lidocaine is often used to induce a block predictive of the result provided by subsequent surgery. Lidocaine has been demonstrated to inhibit the Hoffmann (H) reflex to a greater extent than the direct motor (M) response induced by electrical stimulation, but the timecourse of these responses has not been investigated. An animal (rat) model of the effects of lidocaine on M and H responses was therefore developed to assess this time course. M and H responses were recorded in 18 adult rats before and after application of lidocaine to the sciatic nerve. Two to five minutes after lidocaine injection, M responses were markedly reduced (mean reduction of 44%) and H reflexes were completely abolished. Changes were observed more rapidly for the H reflex. The effects of lidocaine then persisted for 100 minutes. The effect of lidocaine was therefore more prolonged on the H reflex than on the M response. This study confirms that lidocaine blocks not only alpha motoneurons but also Ia afferent fibres responsible for the H reflex. The authors describe, for the first time, the detailed time course of the effect of lidocaine on direct or reflex activation of motoneurons in the rat.

The Relationship between MOC Reflex and Masked Threshold

PubMed Central

Garinis, Angela; Werner, Lynne; Abdala, Carolina

2011-01-01

Otoacoustic emission (OAE) amplitude can be reduced by acoustic stimulation. This effect is produced by the medial olivocochlear (MOC) reflex. Past studies have shown that the MOC reflex is related to listening in noise and attention. In the present study, the relationship between strength of the contralateral MOC reflex and masked threshold was investigated in 19 adults. Detection thresholds were determined for a 1000-Hz, 300-ms tone presented simultaneously with one repetition of a 300-ms masker in an ongoing train of 300-ms masker bursts at 600-ms intervals. Three masking conditions were tested: 1) broadband noise 2) a fixed-frequency 4-tone complex masker and 3) a random-frequency 4-tone complex masker. Broadband noise was expected to produce energetic masking and the tonal maskers were expected to produce informational masking in some listeners. DPOAEs were recorded at fine frequency interval from 500 to 4000 Hz, with and without contralateral acoustic stimulation. MOC reflex strength was estimated as a reduction in baseline level and a shift in frequency of DPOAE fine-structure maxima near 1000-Hz. MOC reflex and psychophysical testing were completed in separate sessions. Individuals with poorer thresholds in broadband noise and in random-frequency maskers were found to have stronger MOC reflexes. PMID:21878379

The role of nervus intermedius in side specific nasal responses.

PubMed

Nichani, J R; Malik, V; Woolford, T J; Ramsden, R T; Homer, J J

2010-03-02

Nervus intermedius (NI) dysfunction is common in patients who have had vestibular schwannoma (VS) surgery. Such patients have a unilateral parasympathetic-denervated nasal cavity. A number of side-specific nasal reflexes have been demonstrated in normal individuals, including hand cold-water immersion. It is not understood whether these reflexes have parasympathetic or sympathic efferent pathways. We aimed to evaluate the side specific nasal reflex to cold-water immersion in post-operative VS patients with NI dysfunction, in order to determine the nature of the efferent pathway of these reflexes. Side specific responses to cold-water immersion were tested by acoustic rhinometry in 10 normal individuals and 18 patients with NI dysfunction (proven by Schirmer s test) after VS surgery. A consistent pattern of ipsilateral congestion and contralateral decongestion after the cold-water immersion was seen in normal individuals (p smaller than 0.001). We found no consistent response in VS patients both ipsilateral and contralateral to the side of NI dysfunction. We confirm the consistent side-specific nasal reflexes to cold-water hand immersion in normal individuals. This is disturbed in patients with NI dysfunction. We have also shown unexpectantly that the contralateral side-specific reflex is disturbed in these patients. These data suggest that the reflex is parasympathetic and crosses the midline.

Effects of pirfenidone on increased cough reflex sensitivity in guinea pigs.

PubMed

Okazaki, Akihito; Ohkura, Noriyuki; Fujimura, Masaki; Katayama, Nobuyuki; Kasahara, Kazuo

2013-10-01

Pirfenidone, an antifibrotic drug with anti-inflammatory and antioxidant effects, delays fibrosis in idiopathic pulmonary fibrosis (IPF). Patients with IPF have a greater cough reflex sensitivity to inhaled capsaicin than healthy people, and cough is an independent predictor of IPF disease progression; however, the effects of pirfenidone on cough reflex sensitivity are unknown. After challenge with an aerosolized antigen in actively sensitized guinea pigs, pirfenidone was administered intraperitoneally, and the cough reflex sensitivity was measured at 48 h after the challenge. Bronchoalveolar lavage (BAL) was performed, and the tracheal tissue was collected. Pirfenidone suppressed the capsaicin-induced increase in cough reflex sensitivity in a dose-dependent manner. Additionally, increased levels of prostaglandin E2, substance P, and leukotriene B4, but not histamine, in the BAL fluid were dose dependently suppressed by pirfenidone. The decrease in neutral endopeptidase activity in the tracheal tissue was also alleviated by pirfenidone treatment. The total number of cells and components in the BAL fluid was not influenced. These results suggest that pirfenidone ameliorates isolated cough based on increased cough reflex sensitivity associated with allergic airway diseases, and potentially relieve chronic cough in IPF patients who often have increased cough reflex sensitivity. Prospective studies on cough-relieving effects of pirfenidone in patients with IPF are therefore warranted. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

PubMed

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.

The behaviour of the long-latency stretch reflex in patients with Parkinson's disease

PubMed Central

Rothwell, Jc; Obeso, Ja; Traub, Mm; Marsden, Cd

1983-01-01

The size of the long-latency stretch reflex was measured in a proximal (triceps) and distal (flexor pollicis longus) muscle in 47 patients with Parkinson's disease, and was compared with that seen in a group of 12 age-matched normal control subjects. The patients were classified clinically into four groups according to the degree of rigidity at the elbow or tremor. Stretch reflexes were evaluated while the subject was exerting a small force against a constant preload supplied by a torque motor, and the size of the reflex response was measured as fractional increase over basal levels of activity. When stretches were given at random intervals by increasing the force exerted by the motor by a factor of 2 or 3, there was a clear trend for the more severely affected patients to have larger long latency responses in the triceps muscle, although there was no change in the size of the short-latency, spinal component of the response. In contrast, there was no change in the size of the long-latency response of the flexor pollicis longus in any group of patients with Parkinson's disease. Despite any differences in reflex size, the inherent muscle stiffness of both muscles appeared to be normal in all groups of patients with Parkinson's disease, since the displacement trajectory of the limb following the force increase was the same as control values in the short (25 ms) period before reflex compensation could intervene. In 20 of the patients and in seven of the control subjects, servo-controlled, ramp positional disturbances were given to the thumb. Up to a velocity of 300°/s, the size of the long-latency stretch reflex was proportional to the log velocity of stretch. This technique revealed, in both moderately and severely rigid patients, increases in the reflex sensitivity of the flexor pollicis longus, which had not been clear using step torque stretches alone. However, whether using ramp or step displacements, long latency stretch reflex gain was not closely related to rigidity; reflex size was within the normal range in many patients with severe rigidity. Enhanced long latency stretch reflexes thus contribute to, but may not be solely responsible for, rigidity in Parkinson's disease. PMID:6842198

Child–Computer Interaction at the Beginner Stage of Music Learning: Effects of Reflexive Interaction on Children’s Musical Improvisation

PubMed Central

Addessi, Anna Rita; Anelli, Filomena; Benghi, Diber; Friberg, Anders

2017-01-01

In this article children’s musical improvisation is investigated through the “reflexive interaction” paradigm. We used a particular system, the MIROR-Impro, implemented in the framework of the MIROR project (EC-FP7), which is able to reply to the child playing a keyboard by a “reflexive” output, mirroring (with repetitions and variations) her/his inputs. The study was conducted in a public primary school, with 47 children, aged 6–7. The experimental design used the convergence procedure, based on three sample groups allowing us to verify if the reflexive interaction using the MIROR-Impro is necessary and/or sufficient to improve the children’s abilities to improvise. The following conditions were used as independent variables: to play only the keyboard, the keyboard with the MIROR-Impro but with not-reflexive reply, the keyboard with the MIROR-Impro with reflexive reply. As dependent variables we estimated the children’s ability to improvise in solos, and in duets. Each child carried out a training program consisting of 5 weekly individual 12 min sessions. The control group played the complete package of independent variables; Experimental Group 1 played the keyboard and the keyboard with the MIROR-Impro with not-reflexive reply; Experimental Group 2 played only the keyboard with the reflexive system. One week after, the children were asked to improvise a musical piece on the keyboard alone (Solo task), and in pairs with a friend (Duet task). Three independent judges assessed the Solo and the Duet tasks by means of a grid based on the TAI-Test for Ability to Improvise rating scale. The EG2, which trained only with the reflexive system, reached the highest average results and the difference with EG1, which did not used the reflexive system, is statistically significant when the children improvise in a duet. The results indicate that in the sample of participants the reflexive interaction alone could be sufficient to increase the improvisational skills, and necessary when they improvise in duets. However, these results are in general not statistically significant. The correlation between Reflexive Interaction and the ability to improvise is statistically significant. The results are discussed on the light of the recent literature in neuroscience and music education. PMID:28184205

Spastic long-lasting reflexes in the awake rat after sacral spinal cord injury.

PubMed

Bennett, D J; Sanelli, L; Cooke, C L; Harvey, P J; Gorassini, M A

2004-05-01

Following chronic sacral spinal cord transection in rats the affected tail muscles exhibit marked spasticity, with characteristic long-lasting tail spasms evoked by mild stimulation. The purpose of the present paper was to characterize the long-lasting reflex seen in tail muscles in response to electrical stimulation of the tail nerves in the awake spastic rat, including its development with time and relation to spasticity. Before and after sacral spinal transection, surface electrodes were placed on the tail for electrical stimulation of the caudal nerve trunk (mixed nerve) and for recording EMG from segmental tail muscles. In normal and acute spinal rats caudal nerve trunk stimulation evoked little or no EMG reflex. By 2 wk after injury, the same stimulation evoked long-lasting reflexes that were 1) very low threshold, 2) evoked from rest without prior EMG activity, 3) of polysynaptic latency with >6 ms central delay, 4) about 2 s long, and 5) enhanced by repeated stimulation (windup). These reflexes produced powerful whole tail contractions (spasms) and developed gradually over the weeks after the injury (< or =52 wk tested), in close parallel to the development of spasticity. Pure low-threshold cutaneous stimulation, from electrical stimulation of the tip of the tail, also evoked long-lasting spastic reflexes, not seen in acute spinal or normal rats. In acute spinal rats a strong C-fiber stimulation of the tip of the tail (20 x T) could evoke a weak EMG response lasting about 1 s. Interestingly, when this C-fiber stimulation was used as a conditioning stimulation to depolarize the motoneuron pool in acute spinal rats, a subsequent low-threshold stimulation of the caudal nerve trunk evoked a 300-500 ms long reflex, similar to the onset of the long-lasting reflex in chronic spinal rats. A similar conditioned reflex was not seen in normal rats. Thus there is an unusually long low-threshold polysynaptic input to the motoneurons (pEPSP) that is normally inhibited by descending control. This pEPSP is released from inhibition immediately after injury but does not produce a long-lasting reflex because of a lack of motoneuron excitability. With chronic injury the motoneuron excitability is increased markedly, and the pEPSP then triggers sustained motoneuron discharges associated with long-lasting reflexes and muscle spasms.

Asymmetrical dispersal and putative isolation-by-distance of an intertidal blenniid across the Atlantic–Mediterranean divide

PubMed Central

Cunha, Regina L.; Faria, Cláudia; Velasco, Eva M.; Robalo, Joana I.

2017-01-01

Transition zones are of high evolutionary interest because unique patterns of spatial variation are often retained. Here, we investigated the phylogeography of the peacock blenny, Salaria pavo, a small marine intertidal fish that inhabits rocky habitats of the Mediterranean and the adjacent Atlantic Ocean. We screened 170 individuals using mitochondrial and nuclear sequence data from eight locations. Four models of genetic structure were tested: panmixia, isolation-by-distance, secondary contact and phylogeographic break. Results indicated clear asymmetric migration from the Mediterranean to the Atlantic but only marginally supported the isolation-by-distance model. Additionally, the species displays an imprint of demographic expansion compatible with the last glacial maximum. Although the existence of a refugium in the Mediterranean cannot be discarded, the ancestral lineage most likely originated in the Atlantic, where most of the genetic diversity occurs. PMID:28462020

Opioid modulation of reflex versus operant responses following stress in the rat.

PubMed

King, C D; Devine, D P; Vierck, C J; Mauderli, A; Yezierski, R P

2007-06-15

In pre-clinical models intended to evaluate nociceptive processing, acute stress suppresses reflex responses to thermal stimulation, an effect previously described as stress-induced "analgesia." Suggestions that endogenous opioids mediate this effect are based on demonstrations that stress-induced hyporeflexia is enhanced by high dose morphine (>5 mg/kg) and is reversed by naloxone. However, reflexes and pain sensations can be modulated differentially. Therefore, in the present study direct comparisons were made of opioid agonist and antagonist actions, independently and in combination with acute restraint stress in Long Evans rats, on reflex lick-guard (L/G) and operant escape responses to nociceptive thermal stimulation (44.5 degrees C). A high dose of morphine (>8 mg/kg) was required to reduce reflex responding, but a moderate dose of morphine (1 mg/kg) significantly reduced escape responding. The same moderate dose (and also 5 mg/kg) of morphine significantly enhanced reflex responding. Naloxone (3 mg/kg) significantly enhanced escape responding but did not affect L/G responding. Restraint stress significantly suppressed L/G reflexes (hyporeflexia) but enhanced escape responses (hyperalgesia). Stress-induced hyperalgesia was significantly reduced by morphine and enhanced by naloxone. In contrast, stress-induced hyporeflexia was blocked by both naloxone and 1 mg/kg of morphine. Thus, stress-induced hyperalgesia was opposed by endogenous opioid release and by administration of morphine. Stress-induced hyporeflexia was dependent upon endogenous opioid release but was counteracted by a moderate dose of morphine. These data demonstrate a differential modulation of reflex and operant outcome measures by stress and by separate or combined opioid antagonism or administration of morphine.

OPERANT CONDITIONING OF A SPINAL REFLEX CAN IMPROVE LOCOMOTION AFTER SPINAL CORD INJURY IN HUMANS

PubMed Central

Thompson, Aiko K.; Pomerantz, Ferne; Wolpaw, Jonathan R.

2013-01-01

Operant conditioning protocols can modify the activity of specific spinal cord pathways and can thereby affect behaviors that use these pathways. To explore the therapeutic application of these protocols, we studied the impact of down-conditioning the soleus H-reflex in people with impaired locomotion caused by chronic incomplete spinal cord injury. After a baseline period in which soleus H-reflex size was measured and locomotion was assessed, subjects completed either 30 H-reflex down-conditioning sessions (DC subjects) or 30 sessions in which the H-reflex was simply measured (Unconditioned (UC) subjects), and locomotion was reassessed. Over the 30 sessions, the soleus H-reflex decreased in two-thirds of the DC subjects (a success rate similar to that in normal subjects) and remained smaller several months later. In these subjects, locomotion became faster and more symmetrical, and the modulation of EMG activity across the step-cycle increased bilaterally. Furthermore, beginning about halfway through the conditioning sessions, all of these subjects commented spontaneously that they were walking faster and farther in their daily lives, and several noted less clonus, easier stepping, and/or other improvements. The H-reflex did not decrease in the other DC subjects or in any of the UC subjects; and their locomotion did not improve. These results suggest that reflex conditioning protocols can enhance recovery of function after incomplete spinal cord injuries and possibly in other disorders as well. Because they are able to target specific spinal pathways, these protocols could be designed to address each individual’s particular deficits, and might thereby complement other rehabilitation methods. PMID:23392666

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

PubMed

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.

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

PubMed

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)

Alterations of brain network hubs in reflex syncope: Evidence from a graph theoretical analysis based on DTI.

PubMed

Park, Bong Soo; Lee, Yoo Jin; Park, Jin-Han; Kim, Il Hwan; Park, Si Hyung; Lee, Ho-Joon; Park, Kang Min

2018-06-01

We evaluated global topology and organization of regional hubs in the brain networks and microstructural abnormalities in the white matter of patients with reflex syncope. Twenty patients with reflex syncope and thirty healthy subjects were recruited, and they underwent diffusion tensor imaging (DTI) scans. Graph theory was applied to obtain network measures based on extracted DTI data, using DSI Studio. We then investigated differences in the network measures between the patients with reflex syncope and the healthy subjects. We also analyzed microstructural abnormalities of white matter using tract-based spatial statistics analysis (TBSS). Measures of global topology were not different between patients with reflex syncope and healthy subjects. However, in reflex syncope patients, the strength measures of the right angular, left inferior frontal, left middle orbitofrontal, left superior medial frontal, and left middle temporal gyrus were lower than in healthy subjects. The betweenness centrality measures of the left middle orbitofrontal, left fusiform, and left lingual gyrus in patients were lower than those in healthy subjects. The PageRank centrality measures of the right angular, left middle orbitofrontal, and left superior medial frontal gyrus in patients were lower than those in healthy subjects. Regarding the analysis of the white matter microstructure, there were no differences in the fractional anisotropy and mean diffusivity values between the two groups. We have identified a reorganization of network hubs in the brain network of patients with reflex syncope. These alterations in brain network may play a role in the pathophysiologic mechanism underlying reflex syncope. © 2018 The Authors. Brain and Behavior published by Wiley Periodicals, Inc.

Avian reflex and electroencephalogram responses in different states of consciousness.

PubMed

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 (<1 min) after respiratory arrest and brain death (isoelectric EEG). The results confirm that the nictitating membrane reflex is a conservative measure of death in poultry. Using spectral analyses of the EEG waveforms it was possible to readily distinguish between the different states of clinical consciousness. In all cases, when birds progressed from a conscious to unconscious state; total spectral 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.

Oxygen-conserving reflexes of the brain: the current molecular knowledge.

PubMed

Schaller, B; Cornelius, J F; Sandu, N; Ottaviani, G; Perez-Pinzon, M A

2009-04-01

The trigemino-cardiac reflex (TCR) may be classified as a sub-phenomenon in the group of the so-called 'oxygen-conserving reflexes'. Within seconds after the initiation of such a reflex, there is neither a powerful and differentiated activation of the sympathetic system with subsequent elevation in regional cerebral blood flow (CBF) with no changes in the cerebral metabolic rate of oxygen (CMRO(2)) or in the cerebral metabolic rate of glucose (CMRglc). Such an increase in regional CBF without a change of CMRO(2) or CMRglc provides the brain with oxygen rapidly and efficiently and gives substantial evidence that the TCR is an oxygen-conserving reflex. This system, which mediates reflex protection projects via currently undefined pathways from the rostral ventrolateral medulla oblongata to the upper brainstem and/or thalamus which finally engage a small population of neurons in the cortex. This cortical centre appears to be dedicated to reflexively transduce a neuronal signal into cerebral vasodilatation and synchronization of electrocortical activity. Sympathetic excitation is mediated by cortical-spinal projection to spinal pre-ganglionic sympathetic neurons whereas bradycardia is mediated via projections to cardiovagal motor medullary neurons. The integrated reflex response serves to redistribute blood from viscera to brain in response to a challenge to cerebral metabolism, but seems also to initiate a preconditioning mechanism. Better and more detailed knowledge of the cascades, transmitters and molecules engaged in such endogenous (neuro) protection may provide new insights into novel therapeutic options for a range of disorders characterized by neuronal death and into cortical organization of the brain.

The effect of binocular eye position and head rotation plane on the human torsional vestibuloocular reflex.

PubMed

Migliaccio, Americo A; Della Santina, Charles C; Carey, John P; Minor, Lloyd B; Zee, David S

2006-08-01

We examined how the gain of the torsional vestibulo-ocular reflex (VOR) (defined as the instantaneous eye velocity divided by inverted head velocity) in normal humans is affected by eye position, target distance, and the plane of head rotation. In six normal subjects we measured three-dimensional (3D) eye and head rotation axes using scleral search coils, and 6D head position using a magnetic angular and linear position measurement device, during low-amplitude (approximately 20 degrees ), high-velocity (approximately 200 degrees/s), high-acceleration (approximately 4000 degrees /s2) rapid head rotations or 'impulses.' Head impulses were imposed manually and delivered in five planes: yaw (horizontal canal plane), pitch, roll, left anterior-right posterior canal plane (LARP), and right anterior-left posterior canal plane (RALP). Subjects were instructed to fix on one of six targets at eye level. Targets were either straight-ahead, 20 degrees left or 20 degrees right from midline, at distance 15 or 124 cm from the subject. Two subjects also looked at more eccentric targets, 30 degrees left or 30 degrees right from midline. We found that the vertical and horizontal VOR gains increased with the proximity of the target to the subject. Previous studies suggest that the torsional VOR gain should decrease with target proximity. We found, however, that the torsional VOR gain did not change for all planes of head rotation and for both target distances. We also found a dynamic misalignment of the vertical positions of the eyes during the torsional VOR, which was greatest during near viewing with symmetric convergence. This dynamic vertical skew during the torsional VOR arises, in part, because when the eyes are converged, the optical axes are not parallel to the naso-occipital axes around which the eyes are rotating. In five of six subjects, the average skew ranged 0.9 degrees -2.9 degrees and was reduced to <0.4 degrees by a 'torsional' quick-phase (around the naso-occipital axis) occurring <110 ms after the onset of the impulse. We propose that the torsional quick-phase mechanism during the torsional VOR could serve at least three functions: (1) resetting the retinal meridians closer to their usual orientation in the head, (2) correcting for the 'skew' deviation created by misalignment between the axes around which the eyes are rotating and the line of sight, and (3) taking the eyes back toward Listing's plane.

Morphometric analysis of the working zone for endoscopic lumbar discectomy.

PubMed

Min, Jun-Hong; Kang, Shin-Hyuk; Lee, Jang-Bo; Cho, Tai-Hyoung; Suh, Jung-Keun; Rhyu, Im-Joo

2005-04-01

Our study's purpose was to analyze the working zone for the current practice of endoscopic discectomy at the lateral exit zone of the intervertebral foramen (IVF) and to define a safe point for clinical practice. One hundred eighty-six nerve roots of the lumbar IVFs of cadaveric spines were studied. Upon lateral inspection, we measured the distance from the nerve root to the most dorsolateral margin of the disc and to the lateral edge of the superior articular process of the vertebra below at the plane of the superior endplate of the vertebra below. The angle between the root and the plane of the disc was also measured. The results showed that the mean distance from the nerve root to the most dorsolateral margin of the disc was 3.4 +/- 2.7 mm (range 0.0-10.8 mm), the mean distance from the nerve root to the lateral edge of the superior articular process of the vertebra below was 11.6 +/- 4.6 mm (range 4.1-24.3 mm), and the mean angle between the nerve root and the plane of the disc was 79.1 degrees +/- 7.6 degrees (range 56.0-90.0 degrees ). The values of the base of the working zone have a wide distribution. Blind puncture of annulus by the working cannula or obturator may be dangerous. The safer procedure would be the direct viewing of the annulus by endoscopy before annulotomy; the working cannula should be inserted into the foramen as close as possible to the facet joint.

A paleolatitude reconstruction of the South Armenian Block (Lesser Caucasus) for the Late Cretaceous: Constraints on the Tethyan realm

NASA Astrophysics Data System (ADS)

Meijers, Maud J. M.; Smith, Brigitte; Kirscher, Uwe; Mensink, Marily; Sosson, Marc; Rolland, Yann; Grigoryan, Araik; Sahakyan, Lilit; Avagyan, Ara; Langereis, Cor; Müller, Carla

2015-03-01

The continental South Armenian Block - part of the Anatolide-Tauride South Armenian microplate - of Gondwana origin rifted from the African margin after the Triassic and collided with the Eurasian margin after the Late Cretaceous. During the Late Cretaceous, two northward dipping subduction zones were simultaneously active in the northern Neo-Tethys between the South Armenian Block in the south and the Eurasian margin in the north: oceanic subduction took place below the continental Eurasian margin and intra-oceanic subduction resulted in ophiolite obduction onto the South Armenian Block in the Late Cretaceous. The paleolatitude position of the South Armenian Block before its collision with Eurasia within paleogeographic reconstructions is poorly determined and limited to one study. This earlier study places the South Armenian Block at the African margin in the Early Jurassic. To reconstruct the paleolatitude history of the South Armenian Block, we sampled Upper Devonian-Permian and Cretaceous sedimentary rocks in Armenia. The sampled Paleozoic rocks have likely been remagnetized. Results from two out of three sites sampled in Upper Cretaceous strata pass fold tests and probably all three carry a primary paleomagnetic signal. The sampled sedimentary rocks were potentially affected by inclination shallowing. Therefore, two sites that consist of a large number of samples (> 100) were corrected for inclination shallowing using the elongation/inclination method. These are the first paleomagnetic data that quantify the South Armenian Block's position in the Tethys ocean between post-Triassic rifting from the African margin and post-Cretaceous collision with Eurasia. A locality sampled in Lower Campanian Eurasian margin sedimentary rocks and corrected for inclination shallowing, confirms that the corresponding paleolatitude falls on the Eurasian paleolatitude curve. The north-south distance between the South Armenian Block and the Eurasian margin just after Coniacian-Santonian ophiolite obduction was at most 1000 km.

Encouraging Reflexivity in Urban Geography Fieldwork: Study Abroad Experiences in Singapore and Malaysia

ERIC Educational Resources Information Center

Glass, Michael R.

2014-01-01

Fieldwork in urban geography courses can encourage reflexivity among students regarding the cities they encounter. This article outlines how student reflexivity was encouraged within a new international field research course in Singapore and Malaysia. Drawing on examples from students' field exercises written during an intensive and occasionally…

Iris Pigmentation and Fractionated Reaction and Reflex Time.

ERIC Educational Resources Information Center

Hale, Bruce D.; And Others

Behavioral measures, fractionated reaction and reflex times by means of electromyography, were used to determine if the eye color differences are found in the central or peripheral regions of the nervous system. The purpose of this research was to determine the truth of the hypothesis that dark-eyed individuals have faster reflex and reaction time…

Approaches to Reflexivity: Navigating Educational and Career Pathways

ERIC Educational Resources Information Center

Dyke, Martin; Johnston, Brenda; Fuller, Alison

2012-01-01

This paper provides a critical appraisal of approaches to reflexivity in sociology. It uses data from social network research to argue that Archer's approach to reflexivity provides a valuable lens with which to understand how people navigate their education and career pathways. The paper is also critical of Archer's methodology and typology of…

"Madam, Are You One of Them?" "Reflexivities of Discomfort" in Researching an "Illicit" Subject

ERIC Educational Resources Information Center

Namatende-Sakwa, Lydia

2018-01-01

Informed largely by Affect theory (2004), this paper takes up "reflexivities of discomfort" to reflexively engage with my affective struggles as a Christian, heterosexual, mother, educator, undertaking a study on homosexuality, which is a thorny issue in Uganda. It a methodological prologue, reflecting my thoughts and struggles before I…

Favouring Reflexivity in Technology-Enhanced Learning Systems: Towards Smart Uses of Traces

ERIC Educational Resources Information Center

George, Sébastien; Michel, Christine; Ollagnier-Beldame, Magali

2016-01-01

During learning activities, reflexive processes allow learners to realise what they have done, understand why, decide on new actions and gain motivation. They help learners to regulate their actions by themselves, that is, to develop metacognitive regulation skills. Computer environments can support reflexive processes to support human learning,…

Changes in Soleus H-Reflex Modulation after Treadmill Training in Children with Cerebral Palsy

ERIC Educational Resources Information Center

Hodapp, Maike; Vry, Julia; Mall, Volker; Faist, Michael

2009-01-01

In healthy children, short latency leg muscle reflexes are profoundly modulated throughout the step cycle in a functionally meaningful way and contribute to the electromyographic (EMG) pattern observed during gait. With maturation of the corticospinal tract, the reflex amplitudes are depressed via supraspinal inhibitory mechanisms. In the soleus…

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

PubMed

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.

Effect of cervicolabyrinthine impulsation on the spinal reflex apparatus

NASA Technical Reports Server (NTRS)

Yarotskiy, A. I.

1980-01-01

In view of the fact that the convergence effect of vestibular impulsation may both stimulate and inhibit intra and intersystemic coordination of physiological processes, an attempt was made to define the physiological effect on the spinal reflex apparatus of the convergence of cervicolabyrinthine impulsation on a model of the unconditioned motor reflex as a mechanism of the common final pathway conditioning the formation and realization of a focused beneficial result of human motor activities. More than 100 persons subjected to rolling effect and angular acceleration during complexly coordinated muscular loading were divided according to typical variants of the functional structure of the patella reflex in an experiment requiring 30 rapid counterclockwise head revolutions at 2/sec with synchronous recording of a 20 item series of patella reflex acts. A knee jerk coefficient was used in calculations. In 85 percent of the cases 2 patellar reflexograms show typical braking and release of knee reflex and 1 shows an extreme local variant. The diagnostic and prognostic value of these tests is suggested for determining adaptive possibilities of functional systems in respect to acceleration and proprioceptive stimuli.

Contraction induced h reflexes in the diagnosis of cervical radiculopathy.

PubMed

Bodofsky, Elliot B; Campellone, Joseph V; Cohen, Stephen J; Caten, Holly N; Schindelheim, Adam M

2015-06-01

To determine whether Contraction Induced H Reflexes (CIHR) can accurately detect cervical radiculopathy. Comparison of CIHR results with Needle Electromyography at academic outpatient Electromyography/Nerve Conduction laboratories. Participants were all patients over 18 with a needle electromyography diagnosis of cervical radiculopathy. Patients were tested for CIHR in at least two upper extremity muscles in electromyographically proven myotomes bilaterally. Patients were requested to perform a moderate contraction while stimulus was applied proximally (elbow or Erb's point). Outcome measures included H Reflex onset latency and side-to-side latency differences. These were compared against previously established normal values. Overall, 10 of 15 patients who met criteria for cervical radiculopathy showed CIHR abnormalities (sensitivity = 67%; 95% confidence interval, 43-91). Counting each side and level separately, CIHR identified 16/27 radiculopathies (sensitivity = 59.2%; 95% confidence interval, 40.6-77.8). Contraction Induced H Reflexes identified 1 possible radiculopathy not seen on electromyography (specificity = 98%; 95% confidence interval, 95-100). Contraction induced H Reflexes have a sensitivity and specificity for cervical radiculopathy similar to the resting Gastroc-Soleus H Reflex.

Astronomers, Transits of Venus, and the Birth of Experimental Psychology

NASA Astrophysics Data System (ADS)

Sheehan, William; Thurber, S.

2012-01-01

The eighteenth century transits of Venus were regarded as the most important astronomical events of their era. Halley's expectation was that by observing the contact points between the limbs of Venus and the Sun, this distance could be determined to an accuracy of one part in 500. But in the event, it proved otherwise. But, as the British historian Agnes Clerke wrote in 1902: "A transit of Venus seems, at first sight, full of promise for solving the problem of the sun's distance. For nothing would appear easier than to determine exactly either the duration of the passage of a small, dark orb across a large brilliant disc, or the instant of its entry upon or exit from it". But in that word `exactly' what snares and pitfalls lie hid!” In the post-mortem analysis of the disappointing results, astronomers devoted a great deal of effort to understand the sources of errors. They rehearsed their observational techniques by observing, under strictly controlled conditions, transits of artificial planets across artificial Suns, and studied such parameters as attention and reflex reaction. In the process, the transits of Venus provided an important impetus to the early development of experimental psychology.

Unusual Presentation of Spasm of Near Reflex Mimicking Large-Angle Acute Acquired Comitant Esotropia

PubMed Central

Shanker, Varshini; Nigam, Vishal

2015-01-01

Abstract We report the case of an 11-year-old boy who presented with sudden esotropia, binocular diplopia, and blurred vision. The patient was neurologically normal. He had a large, constant, comitant, alternating esotropia associated with minimal accommodative spasm. Ocular motility and pupillary reactions were normal. He was diagnosed to have spasm of the near reflex presenting as acute onset of esotropia. The esotropia was persistent despite treatment and eventually resolved with prolonged cycloplegic therapy. This unusual case illustrates that spasm of the near reflex can have unique and variable presentations. Spasm of the near reflex needs to be considered in the differential diagnosis of every case of acute, acquired, comitant esotropia. This is the first case of spasm of the near reflex where persistent esotropia is reported in the absence of any neurological disorder. PMID:27928354

Modulation of spinal reflexes by sexual films of increasing intensity.

PubMed

Both, Stephanie; Boxtel, Geert; Stekelenburg, Jeroen; Everaerd, Walter; Laan, Ellen

2005-11-01

Sexual arousal can be viewed as an emotional state generating sex-specific autonomic and general somatic motor system responses that prepare for sexual action. In the present study modulation of spinal tendious (T) reflexes by sexual films of varying intensity was investigated. T reflexes were expected to increase as a function of increased film intensity. Through use of a between-subjects design, participants were exposed to three erotic films of low, moderate, and high intensity or to three films of moderate intensity. Self-report and genital data confirmed the induction of increasing versus stable levels of sexual arousal. Exposure to the films of increasing intensity resulted in increasing T reflexes. The results indicate that T reflex modulation is sensitive to varying levels of sexual arousal and may be of use in research on behavioral mechanisms underlying appetitive motivation.

Acoustic Reflex Testing in Neonatal Hearing Screening and Subsequent Audiological Evaluation.

PubMed

Jacob-Corteletti, Lilian Cássia Bórnia; Araújo, Eliene Silva; Duarte, Josilene Luciene; Zucki, Fernanda; Alvarenga, Kátia de Freitas

2018-06-18

The aims of the study were to examine the acoustic reflex screening and threshold in healthy neonates and those at risk of hearing loss and to determine the effect of birth weight and gestational age on acoustic stapedial reflex (ASR). We assessed 18 healthy neonates (Group I) and 16 with at least 1 risk factor for hearing loss (Group II); all of them passed the transient evoked otoacoustic emission test that assessed neonatal hearing. The test battery included an acoustic reflex screening with activators of 0.5, 1, 2, and 4 kHz and broadband noise and an acoustic reflex threshold test with all of them, except for the broadband noise activator. In the evaluated neonates, the main risk factors were the gestational age at birth and a low birth weight; hence, these were further analyzed. The lower the gestational age at birth and birth weight, the less likely that an acoustic reflex would be elicited by pure-tone activators. This effect was significant at the frequencies of 0.5, 1, and 2 kHz for gestational age at birth and at the frequencies of 1 and 2 kHz for birth weight. When the broadband noise stimulus was used, a response was elicited in all neonates in both groups. When the pure-tone stimulus was used, the Group II showed the highest acoustic reflex thresholds and the highest percentage of cases with an absent ASR. The ASR threshold varied from 50 to 100 dB HL in both groups. Group II presented higher mean ASR thresholds than Group I, this difference being significant at frequencies of 1, 2, and 4 kHz. Birth weight and gestational age at birth were related to the elicitation of the acoustic reflex. Neonates with these risk factors for hearing impairment were less likely to exhibit the acoustic reflex and had higher thresholds.

Role of the flocculus of the cerebellum in motor learning of the vestibulo-ocular reflex

NASA Technical Reports Server (NTRS)

Highstein, S. M.

1998-01-01

Structure-function studies at the systems level are an effective method for understanding the relationship of the central nervous system to behavior. Motor learning or adaptation of the vestibulo-ocular reflex is a clear example wherein this approach has been productive. During a vestibulo-ocular reflex the brain converts a head velocity signal, transduced through the vestibular semicircular canals, into an eye movement command delivered to the extraocular muscles. If the viewed target remains on the fovea of the retina, the reflex is compensatory, and its gain, eye velocity/head velocity, is one. When the image of the viewed object slips across the retina, visual acuity decreases, and the gain of the reflex, which is no longer one, is plastically adapted or adjusted until retinal stability is restored. The anatomic substrate for this plasticity thus involves brain structures in which visual-vestibular interaction can potentially occur, as well as vestibular and visual sensory and oculomotor motor structures. Further, it has been known for many years that removal of the flocculus of the cerebellum permanently precludes further vestibulo-ocular reflex adaptation, demonstrating the involvement of the cerebellum in this behavior. Maekawa and Simpson (J Neurophysiol 1973;36: 649-66) discovered that one visual input to the flocculus involved the accessory optic system and the inferior olive. Ensuing work has demonstrated that the visual signals used to adapt the vestibulo-ocular reflex are transmitted by this accessory optic system to the flocculus and subsequently to brain stem structures involved in vestibulo-ocular reflex plasticity. Presently the inclusive list of anatomic sites involved in vestibulo-ocular reflex circuitry and its adaptive plasticity is small. Our laboratory continues to believe that this behavior should be caused by interactions within this small class of neurons. By studying each class of identified neuron and its interactions with others within the list, we hope to ultimately understand the mechanisms used by the brain in the expression of this behavior.

Mechanical Characteristics of Reflex Durign Upright Posture in Paralyzed Subjects

NASA Astrophysics Data System (ADS)

Kim, Yongchul; Youm, Youngil; Lee, Bumsuk; Kim, Youngho; Choi, Hyeonki

The characteristics of flexor reflexes have been investigated in the previous studies with human subjects who were seated or supine position. However, researchers did not describe how the spinal circuits are used in different hip angles for paralyzed subjects, such as the standing position with walker or cane. In upright posture the compatibility between a flexor reflex of leg and body balance is a special problem for lower limb injured subjects. Therefore, the purpose of this study was to investigate the effects of hip angle change on the flexor reflex evoked in standing paralyzed subjects supported by walker. In this study, six spinal cord injured and four stroke subjects were recruited through the inpatient physical therapy clinics of Korea national rehabilitation hospital. A single axis electronic goniometer was mounted on the lateral side of the hip joint of the impaired limb to record movements in the sagittal plane at this joint. The electronic goniometer was connected to a data acquisition system, through amplifiers to a computer. Since subject' posture influenced characteristics of the flexion reflex response, the subjects were supported in an upright posture by the help of parallelogram walder. Two series of tests were performed on each leg. The first series of the tests investigated the influence of hip angle during stationary standing posture on flexion reflex response. The hip angle was adjusted by the foot plate. The second examined the effect of the voluntary action of subject on swing motion during the gait. The electrically induced flexion reflex simultaneously produced the flexion of the hip, knee and dorsiflexion of the ankle enabling the swing phase of walking. Form the experimental results we observed that the reflex response of hip joint was largerwith the hip in the extended position than in the flexed position during standing posture. Under voluntary movement on flexion reflex during gaint, the peak hip angle induced by stimulation was increased in spinal cord injury and stroke patients by subject' voluntary movement.

Interaction between the vestibulo-collic reflex and the cervico-collic stretch reflex in the decerebrate cat.

PubMed Central

Dutia, M B; Price, R F

1987-01-01

1. Interactions between the sagittal vestibulo-collic reflex (v.c.r.) and the cervico-collic stretch reflex (c.c.r.) have been studied in the neck extensor muscles biventer cervicis (b.c.) in the decerebrate cat. The v.c.r. was evoked by a 'standard' vestibular stimulus consisting of a sinusoidal nose-up, nose-down head movement of 6-8 deg amplitude at 1 Hz. The c.c.r. was evoked by sinusoidal stretching of the b.c. muscles at 1 Hz. The amplitude of muscle stretching, and its phase in relation to head movement, were systematically varied. 2. When muscle stretching was applied in phase with head movement (so that the muscles were stretched as the head moved in the nose-down direction), the gain of the combined (v.c.r. + c.c.r.) reflex in the b.c. muscles increased above that of the v.c.r. If the muscle stretching was applied out of phase with head movement (so that the muscles shortened as the head moved downward), the gain of the combined reflex was reduced to a value below that of the v.c.r. 3. The effects on the gain of the combined reflex varied in proportion to the amplitude of muscle stretching. The gain and phase of the combined reflex is modelled reasonably well by a linear vectorial addition between the v.c.r. and the c.c.r. over a wide range of amplitudes of muscle stretching. The linear summation model contains a proportionality constant K, which may represent a factor by which the two reflexes are 'calibrated' against each other. 4. If one of the b.c. muscles was held at a fixed length and the other stretched sinusoidally, the c.c.r. was evoked only in the stimulated muscle. Vestibular stimulation then summed with the c.c.r in the stimulated muscle, while on the contralateral side the reflex response was the same as that of the v.c.r. alone. It would appear therefore that the motoneurone pools of the b.c. muscles are organized as independent entities without mutually excitatory or inhibitory reflex linkages. This arrangement presumably allows flexibility in the supraspinal control of the b.c. muscles, which are often used either as synergists during sagittal head movement or as antagonists during horizontal or roll movements of the head. 5. The interaction between the v.c.r. and the c.c.r. results in an apparent 'servo-assistance' role for the muscle afferent feed-back from the b.c. muscles, amplifying or attenuating the reflex response of the muscles to a given head movement.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3498829

Respiratory disease and the oesophagus: reflux, reflexes and microaspiration.

PubMed

Houghton, Lesley A; Lee, Augustine S; Badri, Huda; DeVault, Kenneth R; Smith, Jaclyn A

2016-08-01

Gastro-oesophageal reflux is associated with a wide range of respiratory disorders, including asthma, isolated chronic cough, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease and cystic fibrosis. Reflux can be substantial and reach the proximal margins of the oesophagus in some individuals with specific pulmonary diseases, suggesting that this association is more than a coincidence. Proximal oesophageal reflux in particular has led to concern that microaspiration might have an important, possibly even causal, role in respiratory disease. Interestingly, reflux is not always accompanied by typical reflux symptoms, such as heartburn and/or regurgitation, leading many clinicians to empirically treat for possible gastro-oesophageal reflux. Indeed, costs associated with use of acid suppressants in pulmonary disease far outweigh those in typical GERD, despite little evidence of therapeutic benefit in clinical trials. This Review comprehensively examines the possible mechanisms that might link pulmonary disease and oesophageal reflux, highlighting the gaps in current knowledge and limitations of previous research, and helping to shed light on the frequent failure of antireflux treatments in pulmonary disease.

A Go-type opsin mediates the shadow reflex in the annelid Platynereis dumerilii.

PubMed

Ayers, Thomas; Tsukamoto, Hisao; Gühmann, Martin; Veedin Rajan, Vinoth Babu; Tessmar-Raible, Kristin

2018-04-18

The presence of photoreceptive molecules outside the eye is widespread among animals, yet their functions in the periphery are less well understood. Marine organisms, such as annelid worms, exhibit a 'shadow reflex', a defensive withdrawal behaviour triggered by a decrease in illumination. Herein, we examine the cellular and molecular underpinnings of this response, identifying a role for a photoreceptor molecule of the G o -opsin class in the shadow response of the marine bristle worm Platynereis dumerilii. We found Pdu-Go-opsin1 expression in single specialised cells located in adult Platynereis head and trunk appendages, known as cirri. Using gene knock-out technology and ablation approaches, we show that the presence of Go-opsin1 and the cirri is necessary for the shadow reflex. Consistently, quantification of the shadow reflex reveals a chromatic dependence upon light of approximately 500 nm in wavelength, matching the photoexcitation characteristics of the Platynereis Go-opsin1. However, the loss of Go-opsin1 does not abolish the shadow reflex completely, suggesting the existence of a compensatory mechanism, possibly acting through a ciliary-type opsin, Pdu-c-opsin2, with a Lambda max of approximately 490 nm. We show that a Go-opsin is necessary for the shadow reflex in a marine annelid, describing a functional example for a peripherally expressed photoreceptor, and suggesting that, in different species, distinct opsins contribute to varying degrees to the shadow reflex.

Value of the pinnal-pedal reflex in the diagnosis of canine scabies.

PubMed

Mueller, R S; Bettenay, S V; Shipstone, M

2001-05-19

The potential value of the pinnal-pedal scratch reflex as an aid to diagnosing canine scabies was assessed in 588 dogs with skin disease. The reflex was assessed by vigorously rubbing the tip of one earflap on to the base of the ear for five seconds, and it was considered positive if the ipsilateral hind leg made a scratching movement. A diagnosis of scabies was based on the dog's history, a physical examination and either positive skin scrapings or the complete resolution of pruritus and dermatitis after treatment with ivermectin or milbemycin, with no relapse for at least 12 months. Scabies was diagnosed in 55 of the dogs, allergic skin disease in 463, and 70 had other miscellaneous skin diseases. There was a positive pinnal-pedal scratch reflex in 45 (82 per cent) of the 55 dogs with scabies. Forty (73 per cent) of the dogs with scabies had pinnal dermatitis, and 36 (90 per cent) of these had a positive pinnal-pedal scratch reflex. There was a positive pinnal-pedal scratch reflex in 33 (6.2 per cent) of the other 533 dogs. On the basis of these results, the specificity of testing for scabies by the pinnal-pedal scratch reflex was 93.8 per cent, and the sensitivity was 81.8 per cent The test's positive predictive value was 0.57 and its negative predictive value was 0.98.

Knee joint effusion following ipsilateral hip surgery.

PubMed

Christodoulou, A G; Givissis, P; Antonarakos, P D; Petsatodis, G E; Hatzokos, I; Pournaras, J D

2010-12-01

To correlate patellar reflex inhibition with sympathetic knee joint effusion. 65 women and 40 men aged 45 to 75 (mean, 65) years underwent hip surgery. The surgery entailed dynamic hip screw fixation using the lateral approach with reflection of the vastus lateralis for pertrochantric fractures (n = 49), and hip hemiarthroplasty or total hip replacement using the Watson-Jones approach (n = 38) or hip hemiarthroplasty using the posterior approach (n = 18) for subcapital femoral fractures (n = 28) or osteoarthritis (n = 28). Knee joint effusion, patellar reflex, and thigh circumference were assessed in both legs before and after surgery (at day 0.5, 2, 7, 14, 30, and 45). Time-sequence plots were used for chronological analysis, and correlation between patellar reflex inhibition and knee joint effusion was tested. In the time-sequence plot, the peak frequency of patellar reflex inhibition (on day 0.5) preceded that of the knee joint effusion and the thigh circumference increase (on day 2). Patellar reflex inhibition correlated positively with the knee joint effusion (r = 0.843, p = 0.035). These 2 factors correlated significantly for all 3 surgical approaches (p < 0.0005). All 3 approaches were associated with patellar reflex inhibition on day 0.5 (p = 0.033) and knee joint effusion on day 2 (p = 0.051). Surgical trauma of the thigh may cause patellar reflex inhibition and subsequently knee joint effusion.

Cannabinoid-induced effects on the nociceptive system: a neurophysiological study in patients with secondary progressive multiple sclerosis.

PubMed

Conte, Antonella; Bettolo, Chiara Marini; Onesti, Emanuela; Frasca, Vittorio; Iacovelli, Elisa; Gilio, Francesca; Giacomelli, Elena; Gabriele, Maria; Aragona, Massimiliano; Tomassini, Valentina; Pantano, Patrizia; Pozzilli, Carlo; Inghilleri, Maurizio

2009-05-01

Although clinical studies show that cannabinoids improve central pain in patients with multiple sclerosis (MS) neurophysiological studies are lacking to investigate whether they also suppress these patients' electrophysiological responses to noxious stimulation. The flexion reflex (FR) in humans is a widely used technique for assessing the pain threshold and for studying spinal and supraspinal pain pathways and the neurotransmitter system involved in pain control. In a randomized, double-blind, placebo-controlled, cross-over study we investigated cannabinoid-induced changes in RIII reflex variables (threshold, latency and area) in a group of 18 patients with secondary progressive MS. To investigate whether cannabinoids act indirectly on the nociceptive reflex by modulating lower motoneuron excitability we also evaluated the H-reflex size after tibial nerve stimulation and calculated the H wave/M wave (H/M) ratio. Of the 18 patients recruited and randomized 17 completed the study. After patients used a commercial delta-9-tetrahydrocannabinol (THC) and cannabidiol mixture as an oromucosal spray the RIII reflex threshold increased and RIII reflex area decreased. The visual analogue scale score for pain also decreased, though not significantly. Conversely, the H/M ratio measured before patients received cannabinoids remained unchanged after therapy. In conclusion, the cannabinoid-induced changes in the RIII reflex threshold and area in patients with MS provide objective neurophysiological evidence that cannabinoids modulate the nociceptive system in patients with MS.

Effect of angular velocity on soleus and medial gastrocnemius H-reflex during maximal concentric and eccentric muscle contraction.

PubMed

Duclay, Julien; Robbe, Alice; Pousson, Michel; Martin, Alain

2009-10-01

At rest, the H-reflex is lower during lengthening than shortening actions. During passive lengthening, both soleus (SOL) and medial gastrocnemius (MG) H-reflex amplitudes decrease with increasing angular velocity. This study was designed to investigate whether H-reflex amplitude is affected by angular velocity during concentric and eccentric maximal voluntary contraction (MVC). Experiments were performed on nine healthy men. At a constant angular velocity of 60 degrees /s and 20 degrees /s, maximal H-reflex and M-wave potentials were evoked at rest (i.e., H(max) and M(max), respectively) and during concentric and eccentric MVC (i.e., H(sup) and M(sup), respectively). Regardless of the muscle, H(max)/M(max) was lower during lengthening than shortening actions and the H(sup)/M(sup) ratio was higher than H(max)/M(max) during lengthening actions. Whereas no action type and angular velocity effects on the MG H(sup)/M(sup) were found, the SOL H(sup)/M(sup) was lower during eccentric than concentric MVC and this depression was increased with higher angular velocity. Our findings indicate that the depression of the H-reflex amplitude during eccentric compared to concentric MVC depends mainly on the amount of inhibition induced by lengthening action. In conclusion, H-reflex should be evoked during both passive and active dynamic trials to evaluate the plasticity of the spinal loop.

Neuromuscular performance of lower limbs during voluntary and reflex activity in power- and endurance-trained athletes.

PubMed

Kyröläinen, H; Komi, P V

1994-01-01

Neural, mechanical and muscle factors influence muscle force production. This study was therefore, designed to compare possible differences in the function of the neuromuscular system among differently adapted subjects. A group of 11 power-trained athletes and 10 endurance-trained athletes volunteered as subjects for this study. Maximal voluntary isometric force and the rate of force production of the knee extensor and the plantar flexor muscles were measured. In addition, basic reflex function was measured in the two experimental conditions. The power athletes produced higher voluntary forces (P < 0.01-0.001) with higher rates for force production (P < 0.001) by both muscle groups measured. Unexpectedly, however, no differences were noticed in the electromyogram time curves between the groups. During reflex activity, the endurance group demonstrated higher sensitivity to the mechanical stimuli, i.e. the higher reflex amplitude caused a higher rate of reflex force development, and the reflex amplitude correlated with the averaged angular velocity. The differences in the isometric conditions could be explained by obviously different muscle fibre distribution, by different amounts of muscle mass, by possible differences in the force transmission from individual myofibrils to the skeletal muscle and by specificity of training. In addition, differences in nervous system structure and muscle spindle properties could explain the observed differences in reflex activity between the two groups.

Subspace methods for identification of human ankle joint stiffness.

PubMed

Zhao, Y; Westwick, D T; Kearney, R E

2011-11-01

Joint stiffness, the dynamic relationship between the angular position of a joint and the torque acting about it, describes the dynamic, mechanical behavior of a joint during posture and movement. Joint stiffness arises from both intrinsic and reflex mechanisms, but the torques due to these mechanisms cannot be measured separately experimentally, since they appear and change together. Therefore, the direct estimation of the intrinsic and reflex stiffnesses is difficult. In this paper, we present a new, two-step procedure to estimate the intrinsic and reflex components of ankle stiffness. In the first step, a discrete-time, subspace-based method is used to estimate a state-space model for overall stiffness from the measured overall torque and then predict the intrinsic and reflex torques. In the second step, continuous-time models for the intrinsic and reflex stiffnesses are estimated from the predicted intrinsic and reflex torques. Simulations and experimental results demonstrate that the algorithm estimates the intrinsic and reflex stiffnesses accurately. The new subspace-based algorithm has three advantages over previous algorithms: 1) It does not require iteration, and therefore, will always converge to an optimal solution; 2) it provides better estimates for data with high noise or short sample lengths; and 3) it provides much more accurate results for data acquired under the closed-loop conditions, that prevail when subjects interact with compliant loads.

Next generation control system for reflexive aerostructures

NASA Astrophysics Data System (ADS)

Maddux, Michael R.; Meents, Elizabeth P.; Barnell, Thomas J.; Cable, Kristin M.; Hemmelgarn, Christopher; Margraf, Thomas W.; Havens, Ernie

2010-04-01

Cornerstone Research Group Inc. (CRG) has developed and demonstrated a composite structural solution called reflexive composites for aerospace applications featuring CRG's healable shape memory polymer (SMP) matrix. In reflexive composites, an integrated structural health monitoring (SHM) system autonomously monitors the structural health of composite aerospace structures, while integrated intelligent controls monitor data from the SHM system to characterize damage and initiate healing when damage is detected. Development of next generation intelligent controls for reflexive composites were initiated for the purpose of integrating prognostic health monitoring capabilities into the reflexive composite structural solution. Initial efforts involved data generation through physical inspections and mechanical testing. Compression after impact (CAI) testing was conducted on composite-reinforced shape memory polymer samples to induce damage and investigate the effectiveness of matrix healing on mechanical performance. Non-destructive evaluation (NDE) techniques were employed to observe and characterize material damage. Restoration of mechanical performance was demonstrated through healing, while NDE data showed location and size of damage and verified mitigation of damage post-healing. Data generated was used in the development of next generation reflexive controls software. Data output from the intelligent controls could serve as input to Integrated Vehicle Health Management (IVHM) systems and Integrated Resilient Aircraft Controls (IRAC). Reflexive composite technology has the ability to reduce maintenance required on composite structures through healing, offering potential to significantly extend service life of aerospace vehicles and reduce operating and lifecycle costs.

Auditory Brainstem Circuits That Mediate the Middle Ear Muscle Reflex

PubMed Central

Mukerji, Sudeep; Windsor, Alanna Marie; Lee, Daniel J.

2010-01-01

The middle ear muscle (MEM) reflex is one of two major descending systems to the auditory periphery. There are two middle ear muscles (MEMs): the stapedius and the tensor tympani. In man, the stapedius contracts in response to intense low frequency acoustic stimuli, exerting forces perpendicular to the stapes superstructure, increasing middle ear impedance and attenuating the intensity of sound energy reaching the inner ear (cochlea). The tensor tympani is believed to contract in response to self-generated noise (chewing, swallowing) and nonauditory stimuli. The MEM reflex pathways begin with sound presented to the ear. Transduction of sound occurs in the cochlea, resulting in an action potential that is transmitted along the auditory nerve to the cochlear nucleus in the brainstem (the first relay station for all ascending sound information originating in the ear). Unknown interneurons in the ventral cochlear nucleus project either directly or indirectly to MEM motoneurons located elsewhere in the brainstem. Motoneurons provide efferent innervation to the MEMs. Although the ascending and descending limbs of these reflex pathways have been well characterized, the identity of the reflex interneurons is not known, as are the source of modulatory inputs to these pathways. The aim of this article is to (a) provide an overview of MEM reflex anatomy and physiology, (b) present new data on MEM reflex anatomy and physiology from our laboratory and others, and (c) describe the clinical implications of our research. PMID:20870664

Eye movement abnormalities in essential tremor

PubMed Central

Plinta, Klaudia; Krzak-Kubica, Agnieszka; Zajdel, Katarzyna; Falkiewicz, Marcel; Dylak, Jacek; Ober, Jan; Szczudlik, Andrzej; Rudzińska, Monika

2016-01-01

Abstract Essential tremor (ET) is the most prevalent movement disorder, characterized mainly by an action tremor of the arms. Only a few studies published as yet have assessed oculomotor abnormalities in ET and their results are unequivocal. The aim of this study was to assess the oculomotor abnormalities in ET patients compared with the control group and to find the relationship between oculomotor abnormalities and clinical features of ET patients. We studied 50 ET patients and 42 matched by age and gender healthy controls. Saccadometer Advanced (Ober Consulting, Poland) was used to investigate reflexive, pace-induced and cued saccades and conventional electrooculography for evaluation of smooth pursuit and fixation. The severity of the tremor was assessed by the Clinical Rating Scale for Tremor. Significant differences between ET patients and controls were found for the incidence of reflexive saccades dysmetria and deficit of smooth pursuit. Reflexive saccades dysmetria was more frequent in patients in the second and third phase of ET compared to the first phase. The reflexive saccades latency increase was correlated with severity of the tremor. In conclusion, oculomotor abnormalities were significantly more common in ET patients than in healthy subjects. The most common oculomotor disturbances in ET were reflexive saccades dysmetria and slowing of smooth pursuit. The frequency of reflexive saccades dysmetria increased with progression of ET. The reflexive saccades latency increase was related to the severity of tremor. PMID:28149393

The Evolutionary Origin of Female Orgasm.

PubMed

Pavličev, Mihaela; Wagner, Günter

2016-09-01

The evolutionary explanation of female orgasm has been difficult to come by. The orgasm in women does not obviously contribute to the reproductive success, and surprisingly unreliably accompanies heterosexual intercourse. Two types of explanations have been proposed: one insisting on extant adaptive roles in reproduction, another explaining female orgasm as a byproduct of selection on male orgasm, which is crucial for sperm transfer. We emphasize that these explanations tend to focus on evidence from human biology and thus address the modification of a trait rather than its evolutionary origin. To trace the trait through evolution requires identifying its homologue in other species, which may have limited similarity with the human trait. Human female orgasm is associated with an endocrine surge similar to the copulatory surges in species with induced ovulation. We suggest that the homolog of human orgasm is the reflex that, ancestrally, induced ovulation. This reflex became superfluous with the evolution of spontaneous ovulation, potentially freeing female orgasm for other roles. This is supported by phylogenetic evidence showing that induced ovulation is ancestral, while spontaneous ovulation is derived within eutherians. In addition, the comparative anatomy of female reproductive tract shows that evolution of spontaneous ovulation is correlated with increasing distance of clitoris from the copulatory canal. In summary, we suggest that the female orgasm-like trait may have been adaptive, however for a different role, namely for inducing ovulation. With the evolution of spontaneous ovulation, orgasm was freed to gain secondary roles, which may explain its maintenance, but not its origin. © 2016 Wiley Periodicals, Inc.

Thermographic analysis and autonomic response in the hands of patients with leprosy.

PubMed

Cavalheiro, Aretusa Lopes; Costa, Debora Tacon da; Menezes, Ana Luiza Ferro de; Pereira, Janser Moura; Carvalho, Eliane Maria de

2016-01-01

Low temperatures and slow blood flow may result from peripheral neuropathy caused by leprosy, and the simple detection of cold fingers could already be a preliminary classification for these patients. To investigate whether infrared thermography would be able to measure this change in temperature in the hands of people with leprosy. The study assessed 17 leprosy patients who were under treatment at the National Reference Center for Sanitary Dermatology and Leprosy, Uberlândia/MG, and 15 people without leprosy for the control group. The infrared camera FLIR A325 and Therma CAM Researcher Professional 2.9 software were used to measure the temperature. The room was air-conditioned, maintaining the temperature at 25°C; the distance between the camera and the limb was 70 cm. The vasomotor reflex of patients was tested by a cold stress on the palm. The study showed a significant interaction between the clinical form of leprosy and temperature, where the control group and the borderline-borderline form revealed a higher initial temperature, while borderline-lepromatous and lepromatous leprosy showed a lower temperature. Regarding vasomotor reflex, lepromatous leprosy patients were unable to recover the initial temperature after cold stress, while those with the borderline-tuberculoid form not only recovered but exceeded the initial temperature. Thermography proved a potential tool to assist in the early detection of neuropathies, helping in the prevention of major nerve damage and the installation of deformities and disabilities that are characteristic of leprosy.

Valuing water resources in Switzerland using a hedonic price model

NASA Astrophysics Data System (ADS)

van Dijk, Diana; Siber, Rosi; Brouwer, Roy; Logar, Ivana; Sanadgol, Dorsa

2016-05-01

In this paper, linear and spatial hedonic price models are applied to the housing market in Switzerland, covering all 26 cantons in the country over the period 2005-2010. Besides structural house, neighborhood and socioeconomic characteristics, we include a wide variety of new environmental characteristics related to water to examine their role in explaining variation in sales prices. These include water abundance, different types of water bodies, the recreational function of water, and water disamenity. Significant spatial autocorrelation is found in the estimated models, as well as nonlinear effects for distances to the nearest lake and large river. Significant effects are furthermore found for water abundance and the distance to large rivers, but not to small rivers. Although in both linear and spatial models water related variables explain less than 1% of the price variation, the distance to the nearest bathing site has a larger marginal contribution than many neighborhood-related distance variables. The housing market shows to differentiate between different water related resources in terms of relative contribution to house prices, which could help the housing development industry make more geographically targeted planning activities.

Bourdieu's Reflexive Sociology and "Spaces of Points of View": Whose Reflexivity, Which Perspective?

ERIC Educational Resources Information Center

Kenway, Jane; McLeod, Julie

2004-01-01

This paper considers Bourdieu's concepts of perspectivism and reflexivity, looking particularly at how he develops arguments about these in his recent work, The Weight of the World (1999) and Pascalian Meditations (2000b). We explicate Bourdieu's distinctive purposes and deployment of these terms and approaches, and discuss how this compares with…

Processing Reflexives in a Second Language: The Timing of Structural and Discourse-Level Constraints

ERIC Educational Resources Information Center

Felser, Claudia; Cunnings, Ian

2012-01-01

We report the results from two eye-movement monitoring experiments examining the processing of reflexive pronouns by proficient German-speaking learners of second language (L2) English. Our results show that the nonnative speakers initially tried to link English argument reflexives to a discourse-prominent but structurally inaccessible antecedent,…

Reflexive Management Learning: An Integrative Review and a Conceptual Typology

ERIC Educational Resources Information Center

Cotter, Richard J.; Cullen, John G.

2012-01-01

The scale and reach of the recent global financial has created a fresh wave of interest in exploring more sustainable forms of management. A central thrust behind this trend in the practice of management development and education has been the accentuation of reflexivity. There are many variations in how reflexivity is understood, and this article…

Reflexive Language and Ethnic Minority Activism in Hong Kong: A Trajectory-Based Analysis

ERIC Educational Resources Information Center

Pérez-Milans, Miguel; Soto, Carlos

2016-01-01

This article engages with Archer's call to further research on reflexivity and social change under conditions of late modernity (2007, 2010, 2012) from the perspective of existing work on reflexive discourse in the language disciplines (Silverstein 1976, Lucy 1993). Drawing from a linguistic ethnography of the networked trajectories of a group of…

More than Meets the Eye: The Use of Videonarratives to Facilitate Doctoral Students' Reflexivity on Their Doctoral Journeys

ERIC Educational Resources Information Center

Taylor, Carol A.

2011-01-01

This article discusses findings from a UK Higher Education Academy project, which used digital video to promote doctoral students' reflexivity. The project aimed to facilitate doctoral students' research skills through the making of videonarratives; create spaces for reflexivity on the relations between research, narrative and identity; and…

Reflexivity and the Politics of Knowledge: Researchers as "Brokers" and "Translators" of Educational Development

ERIC Educational Resources Information Center

Sriprakash, Arathi; Mukhopadhyay, Rahul

2015-01-01

This paper interrogates the ways in which "reflexivity" has proliferated as a normative methodological discourse in the field of international and comparative education. We argue that the dominant approach to reflexivity foregrounds the standpoints of researchers and their subjects in a way that does not attend to the situated,…

Bourdieu and Science Studies: Toward a Reflexive Sociology

ERIC Educational Resources Information Center

Hess, David J.

2011-01-01

Two of Bourdieu's fundamental contributions to science studies--the reflexive analysis of the social and human sciences and the concept of an intellectual field--are used to frame a reflexive study of the history and social studies of science and technology as an intellectual field in the United States. The universe of large, Ph.D.-granting…

A Comparison of Statistical Models for Calculating Reliability of the Hoffmann Reflex

ERIC Educational Resources Information Center

Christie, A.; Kamen, G.; Boucher, Jean P.; Inglis, J. Greig; Gabriel, David A.

2010-01-01

The Hoffmann reflex is obtained through surface electromyographic recordings, and it is one of the most common neurophysiological techniques in exercise science. Measurement and evaluation of the peak-to-peak amplitude of the Hoffmann reflex has been guided by the observation that it is a variable response that requires multiple trials to obtain a…

More Accurate Definition of Clinical Target Volume Based on the Measurement of Microscopic Extensions of the Primary Tumor Toward the Uterus Body in International Federation of Gynecology and Obstetrics Ib-IIa Squamous Cell Carcinoma of the Cervix

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

Xie, Wen-Jia; Wu, Xiao; Xue, Ren-Liang

Purpose: To more accurately define clinical target volume for cervical cancer radiation treatment planning by evaluating tumor microscopic extension toward the uterus body (METU) in International Federation of Gynecology and Obstetrics stage Ib-IIa squamous cell carcinoma of the cervix (SCCC). Patients and Methods: In this multicenter study, surgical resection specimens from 318 cases of stage Ib-IIa SCCC that underwent radical hysterectomy were included. Patients who had undergone preoperative chemotherapy, radiation, or both were excluded from this study. Microscopic extension of primary tumor toward the uterus body was measured. The association between other pathologic factors and METU was analyzed. Results: Microscopicmore » extension toward the uterus body was not common, with only 12.3% of patients (39 of 318) demonstrating METU. The mean (±SD) distance of METU was 0.32 ± 1.079 mm (range, 0-10 mm). Lymphovascular space invasion was associated with METU distance and occurrence rate. A margin of 5 mm added to gross tumor would adequately cover 99.4% and 99% of the METU in the whole group and in patients with lymphovascular space invasion, respectively. Conclusion: According to our analysis of 318 SCCC specimens for METU, using a 5-mm gross tumor volume to clinical target volume margin in the direction of the uterus should be adequate for International Federation of Gynecology and Obstetrics stage Ib-IIa SCCC. Considering the discrepancy between imaging and pathologic methods in determining gross tumor volume extent, we recommend a safer 10-mm margin in the uterine direction as the standard for clinical practice when using MRI for contouring tumor volume.« less

Imaging Analysis of Hepatoblastoma Resectability Across Neoadjuvant Chemotherapy

PubMed Central

Murphy, Andrew J.; Ayers, Gregory D.; Hilmes, Melissa A.; Mukherjee, Kaushik; Wilson, Kevin J.; Allen, Wade M.; Fernandez-Pineda, Israel; Shinall, Myrick C.; Zhao, Zhiguo; Furman, Wayne L.; McCarville, Mary Beth; Davidoff, Andrew M.; Lovvorn, Harold N.

2013-01-01

Purpose Hepatoblastomas often require neoadjuvant chemotherapy to facilitate partial hepatectomy, which necessitates freedom of tumor borders from the confluence of hepatic veins (COHV), portal vein bifurcation (PVB), and retrohepatic inferior vena cava (IVC). This study aimed to clarify the effect of incremental neoadjuvant cycles on the AHEP0731 protocol criteria of hepatoblastoma resectability. Methods Hepatoblastoma responses to neoadjuvant chemotherapy were analyzed among patients (n=23) treated at two children’s hospitals between 1996 and 2010. Using digital imaging data, ellipsoid and point-based models were created to measure tumor volume regression and respective distances from tumor borders nearest to the COHV, PVB, and IVC. Results Hepatoblastoma volumes regressed with incremental neoadjuvant chemotherapy cycles (p<0.001). Although tumor borders regressed away from the COHV (p=0.008), on average only 1.1mm was gained. No change from tumor borders to the PVB was detected (p=0.102). Distances from tumor borders to the IVC remained stable at one hospital (p=0.612), but increased only 0.15mm every 10 days of therapy at the other (p=0.002). Neoadjuvant chemotherapy induced slightly more tumors to meet the threshold vascular margin of 1cm (baseline to completion): COHV, 11 (47.8%) to 17 (73.9%; p=0.058); PVB, 11 (47.8%) to 15 (65.2%; p=0.157); IVC, 4 (17.4%) to 10 (43.5%; p=0.034). No differences were detected in demographic or disease-specific characteristics between patients who did or did not achieve this 1cm margin after conclusion of chemotherapy. Conclusion Hepatoblastoma volumes regress significantly with increasing neoadjuvant chemotherapy cycles. However, tumors often remain anchored to the major hepatic vasculature, showing marginal improvement in resectability criteria. PMID:23845613

Ocular motor responses to abrupt interaural head translation in normal humans

NASA Technical Reports Server (NTRS)

Ramat, Stefano; Zee, David S.; Shelhamer, M. J. (Principal Investigator)

2003-01-01

We characterized the interaural translational vestibulo-ocular reflex (tVOR) in 6 normal humans to brief (approximately 200 ms), high-acceleration (0.4-1.4g) stimuli, while they fixed targets at 15 or 30 cm. The latency was 19 +/- 5 ms at 15-cm and 20 +/- 12 ms at 30-cm viewing. The gain was quantified using the ratio of actual to ideal behavior. The median position gain (at time of peak head velocity) was 0.38 and 0.37, and the median velocity gain, 0.52 and 0.62, at 15- and 30-cm viewing, respectively. These results suggest the tVOR scales proportionally at these viewing distances. Likewise, at both viewing distances, peak eye velocity scaled linearly with peak head velocity and gain was independent of peak head acceleration. A saccade commonly occurred in the compensatory direction, with a greater latency (165 vs. 145 ms) and lesser amplitude (1.8 vs. 3.2 deg) at 30- than 15-cm viewing. Even with saccades, the overall gain at the end of head movement was still considerably undercompensatory (medians 0.68 and 0.77 at 15- and 30-cm viewing). Monocular viewing was also assessed at 15-cm viewing. In 4 of 6 subjects, gains were the same as during binocular viewing and scaled closely with vergence angle. In sum the low tVOR gain and scaling of the response with viewing distance and head velocity extend previous results to higher acceleration stimuli. tVOR latency (approximately 20 ms) was lower than previously reported. Saccades are an integral part of the tVOR, and also scale with viewing distance.

Longitudinal changes in tooth/single-implant relationship and bone topography: an 8-year retrospective analysis.

PubMed

Chang, Moontaek; Wennström, Jan L

2012-06-01

To evaluate longitudinal changes in tooth/implant relationship and bone topography at single implants with a microthreaded, conical marginal portion (Astra Tech ST® implants, Astra Tech AB, Mölndal, Sweden). Thirty-one subjects with single implant-supported restorations in the esthetic zone were included. Radiographs obtained at crown installation and 1, 5, and 8 years of follow-up were analyzed with regard to changes in (1) bone level at the implant and adjacent teeth and (2) vertical position of adjacent teeth relative to the single implant. The mean marginal bone loss amounted to 0.1 mm at both implants and adjacent teeth during the 8 years of follow-up. Regression analysis failed to identify significant explanatory factors for observed variance in bone level change at the adjacent tooth surfaces. Vertical change in position of the teeth relative to the implants was more frequent and significantly greater in incisor compared with premolar tooth region but not associated with gender or age. The marginal bone level at teeth adjacent to single implants with a microthreaded conical marginal part was not influenced by horizontal and vertical tooth-implant distances. Continuous eruption of adjacent teeth may result in infraocclusal positioning of a single-implant restoration. © 2010 Wiley Periodicals, Inc.

Effects of ischaemia upon reflex electromyographic responses evoked by stretch and vibration in human wrist flexor muscles.

PubMed Central

Cody, F W; Goodwin, C N; Richardson, H C

1987-01-01

1. The reflex electromyographic responses evoked in a wrist flexor muscle, flexor carpi radialis (f.c.r.), by forcible extension of the wrist ('stretch') and by vibration of the flexor tendon have been studied in normal subjects. Reflexes were elicited during the maintenance of a low level of voluntary flexor contraction (5% maximum). Stretch regularly produced a relatively prolonged (ca. 100 ms duration) increase in e.m.g. activity which was usually divisible into short-latency (ca. 25 ms, M1) and long-latency (ca. 50 ms, M2) peaks. Vibration produced a single, phasic peak, at short latency, with no sign of an accompanying long-latency wave comparable to the M2 stretch response. 2. Ischaemia was induced by inflation of a blood-pressure cuff around the upper arm and its effects upon the reflex patterns were studied. During ischaemia M1 stretch responses showed a more rapid and pronounced decline than did M2 responses and were abolished before voluntary power was appreciably affected. Vibration-evoked short-latency peaks changed in an essentially parallel manner to M1 stretch reflexes. During recovery from ischaemia M2 reflexes were restored before short-latency responses. 3. The patterns of reflex reductions in e.m.g. upon withdrawal of stimulation were also studied. Such troughs in activity, under non-ischaemic conditions, regularly commenced at short latency and were of relatively small amplitude. The records of several of the subjects, and particularly ones obtained during ischaemia, suggested that release of stretch (with concomitant stretch of antagonists) could elicit an additive, long-latency decline in e.m.g. The existence of any such separate, delayed component was never observed upon termination of vibration. 4. Measurements of changes in the latencies and durations of reflex components, accompanying the progression of ischaemia, indicated that depression of early reflex activity resulted in part from increases in the latencies of these initial peaks but predominantly reflected simultaneous and separate reductions in their amplitudes. 5. The generation of short-latency reflexes by stretch and vibration, both of which stimuli powerfully excite muscle spindle primary endings, and the marked susceptibility of these responses to ischaemia supports their being mediated by group Ia afferents. The contrasting behaviour of M2 stretch responses, both regarding their absence with vibration and their resistance to ischaemia, suggests that they depend crucially upon a separate group of reflex afferents.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3443959

Researcher Linguistic Vulnerability: A Note on Methodological Implications.

PubMed

Muller, Ashley Elizabeth; Gubrium, Erika

2016-01-01

We reflect on the experiences of a researcher conducting a pilot exercise project with marginalized research participants within the substance use disorder treatment field, in a language that was nonnative to her. While the project collected and analyzed quantitative data, the researcher was motivated by qualitative inquiry's commitment to reducing participant-researcher distance and power differences. Despite multiple sources of power imbalances favoring the researcher, the ability of participants to speak their native language to a nonnative researcher, and the researcher's active recognition of her linguistic vulnerability, appeared to afford them an unexpected source of power within the context of the project. We discuss the researcher's observations of these power dynamics and their implications for cross-cultural research and when working with marginalized research participants. © The Author(s) 2015.

Interaction of reflected ions with the firehose marginally stable current sheet - Implications for plasma sheet convection

NASA Technical Reports Server (NTRS)

Pritchett, P. L.; Coroniti, F. V.

1992-01-01

The firehose marginally stable current sheet, which may model the flow away from the distant reconnection neutral line, assumes that the accelerated particles escape and never return to re-encounter the current region. This assumption fails on the earthward side where the accelerated ions mirror in the geomagnetic dipole field and return to the current sheet at distances up to about 30 R(E) down the tail. Two-dimensional particle simulations are used to demonstrate that the reflected ions drive a 'shock-like' structure in which the incoming flow is decelerated and the Bz field is highly compressed. These effects are similar to those produced by adiabatic choking of steady convection. Possible implications of this interaction for the dynamics of the tail are considered.

Stretch reflex excitability of the anti-gravity ankle extensor muscle in elderly humans.

PubMed

Kawashima, N; Nakazawa, K; Yamamoto, S-I; Nozaki, D; Akai, M; Yano, H

2004-01-01

To examine whether the stretch reflex excitability of the soleus muscle changes with age, stretch reflexes at rest (REST) and during weak voluntary contractions (ACT) were elicited in 18 older and 14 younger subjects. The amplitude of the stretch reflex responses and gain, defined as the gradient of the regression line for the relation between stretch reflex responses against the angular velocity of the applied perturbation, were evaluated in each short-latency (M1) and two long-latency components (M2 and M3). It was found that in the older group, both the amplitude and gain of the M1 component did not change from the REST to the ACT conditions, whereas in the younger group both variables significantly increased from the REST to ACT conditions. The latency of the M1 component was significantly shorter under the REST condition (older vs. younger: 51.8 +/- 7.37 vs. 55.1 +/- 8.69 ms), while no group differences were found in those variables under the ACT condition, suggesting that the muscle-tendon complexes of SOL muscles of the older subjects were less elastic and had less slack, probably due to age-related histochemical alterations. Further, the Hoffman reflex (H-reflex), elicited during the REST condition in 10 older and 11 younger subjects showed no significant differences, suggesting that the soleus motoneuron response to the Ia input was comparable between the two subject groups. The histochemical alterations occurring with the ageing process might augment the short-latency stretch reflex in the SOL muscle without enhancement of motoneuronal excitability, and this effect might be masked when the muscle is voluntarily activated.

The subject-fixated coaxially sighted corneal light reflex: a clinical marker for centration of refractive treatments and devices.

PubMed

Chang, Daniel H; Waring, George O

2014-11-01

To describe the inconsistencies in definition, application, and usage of the ocular reference axes (optical axis, visual axis, line of sight, pupillary axis, and topographic axis) and angles (angle kappa, lambda, and alpha) and to propose a precise, reproducible, clinically defined reference marker and axis for centration of refractive treatments and devices. Perspective. Literature review of papers dealing with ocular reference axes, angles, and centration. The inconsistent definitions and usage of the current ocular axes, as derived from eye models, limit their clinical utility. With a clear understanding of Purkinje images and a defined alignment of the observer, light source/fixation target, and subject eye, the subject-fixated coaxially sighted corneal light reflex can be a clinically useful reference marker. The axis formed by connecting the subject-fixated coaxially sighted corneal light reflex and the fixation point, the subject-fixated coaxially sighted corneal light reflex axis, is independent of pupillary dilation and phakic status of the eye. The relationship of the subject-fixated coaxially sighted corneal light reflex axis to a refined definition of the visual axis without reference to nodal points, the foveal-fixation axis, is discussed. The displacement between the subject-fixated coaxially sighted corneal light reflex and pupil center is described not by an angle, but by a chord, here termed chord mu. The application of the subject-fixated coaxially sighted corneal light reflex to the surgical centration of refractive treatments and devices is discussed. As a clinically defined reference marker, the subject-fixated coaxially sighted corneal light reflex avoids the shortcomings of current ocular axes for clinical application and may contribute to better consensus in the literature and improved patient outcomes. Copyright © 2014 Elsevier Inc. All rights reserved.

Arm Dominance Affects Feedforward Strategy more than Feedback Sensitivity during a Postural Task

PubMed Central

Walker, Elise H. E.; Perreault, Eric J.

2015-01-01

Handedness is a feature of human motor control that is still not fully understood. Recent work has demonstrated that the dominant and nondominant arm each excel at different behaviors, and has proposed that this behavioral asymmetry arises from lateralization in the cerebral cortex: the dominant side specializes in predictive trajectory control, while the nondominant side is specialized for impedance control. Long-latency stretch reflexes are an automatic mechanism for regulating posture, and have been shown to contribute to limb impedance. To determine whether long-latency reflexes also contribute to asymmetric motor behavior in the upper limbs, we investigated the effect of arm dominance on stretch reflexes during a postural task that required varying degrees of impedance control. Our results demonstrated slightly but significantly larger reflex responses in the biarticular muscles of the nondominant arm, as would be consistent with increased impedance control. These differences were attributed solely to higher levels of voluntary background activity in the nondominant biarticular muscles, indicating that feedforward strategies for postural stability may differ between arms. Reflex sensitivity, which was defined as the magnitude of the reflex response for matched levels of background activity, was not significantly different between arms for a broad subject population ranging from 23–51 years of age. These results indicate that inter-arm differences in feedforward strategies are more influential during posture than differences in feedback sensitivity, in a broad subject population. Interestingly, restricting our analysis to subjects under 40 years of age revealed a small increase in long-latency reflex sensitivity in the nondominant arm relative to the dominant arm. Though our subject numbers were small for this secondary analysis, it suggests that further studies may be required to assess the influence of reflex lateralization throughout development. PMID:25850407

Comprehensive neuromechanical assessment in stroke patients: reliability and responsiveness of a protocol to measure neural and non-neural wrist properties.

PubMed

van der Krogt, Hanneke; Klomp, Asbjørn; de Groot, Jurriaan H; de Vlugt, Erwin; van der Helm, Frans Ct; Meskers, Carel Gm; Arendzen, J Hans

2015-03-13

Understanding movement disorder after stroke and providing targeted treatment for post stroke patients requires valid and reliable identification of biomechanical (passive) and neural (active and reflexive) contributors. Aim of this study was to assess test-retest reliability of passive, active and reflexive parameters and to determine clinical responsiveness in a cohort of stroke patients with upper extremity impairments and healthy volunteers. Thirty-two community-residing chronic stroke patients with an impairment of an upper limb and fourteen healthy volunteers were assessed with a comprehensive neuromechanical assessment protocol consisting of active and passive tasks and different stretch reflex-eliciting measuring velocities, using a haptic manipulator and surface electromyography of wrist flexor and extensor muscles (Netherlands Trial Registry number NTR1424). Intraclass correlation coefficients (ICC) and Standard Error of Measurement were calculated to establish relative and absolute test-retest reliability of passive, active and reflexive parameters. Clinical responsiveness was tested with Kruskal Wallis test for differences between groups. ICC of passive parameters were fair to excellent (0.45 to 0.91). ICC of active parameters were excellent (0.88-0.99). ICC of reflexive parameters were fair to good (0.50-0.74). Only the reflexive loop time of the extensor muscles performed poor (ICC 0.18). Significant differences between chronic stroke patients and healthy volunteers were found in ten out of fourteen parameters. Passive, active and reflexive parameters can be assessed with high reliability in post-stroke patients. Parameters were responsive to clinical status. The next step is longitudinal measurement of passive, active and reflexive parameters to establish their predictive value for functional outcome after stroke.

Arm dominance affects feedforward strategy more than feedback sensitivity during a postural task.

PubMed

Walker, Elise H E; Perreault, Eric J

2015-07-01

Handedness is a feature of human motor control that is still not fully understood. Recent work has demonstrated that the dominant and nondominant arm each excel at different behaviors and has proposed that this behavioral asymmetry arises from lateralization in the cerebral cortex: the dominant side specializes in predictive trajectory control, while the nondominant side is specialized for impedance control. Long-latency stretch reflexes are an automatic mechanism for regulating posture and have been shown to contribute to limb impedance. To determine whether long-latency reflexes also contribute to asymmetric motor behavior in the upper limbs, we investigated the effect of arm dominance on stretch reflexes during a postural task that required varying degrees of impedance control. Our results demonstrated slightly but significantly larger reflex responses in the biarticular muscles of the nondominant arm, as would be consistent with increased impedance control. These differences were attributed solely to higher levels of voluntary background activity in the nondominant biarticular muscles, indicating that feedforward strategies for postural stability may differ between arms. Reflex sensitivity, which was defined as the magnitude of the reflex response for matched levels of background activity, was not significantly different between arms for a broad subject population ranging from 23 to 51 years of age. These results indicate that inter-arm differences in feedforward strategies are more influential during posture than differences in feedback sensitivity, in a broad subject population. Interestingly, restricting our analysis to subjects under 40 years of age revealed a small increase in long-latency reflex sensitivity in the nondominant arm relative to the dominant arm. Though our subject numbers were small for this secondary analysis, it suggests that further studies may be required to assess the influence of reflex lateralization throughout development.

Pre- and post-alpha motoneuronal control of the soleus H-reflex during sinusoidal hip movements in human spinal cord injury

PubMed Central

Knikou, Maria; Chaudhuri, Debjani; Kay, Elizabeth; Schmit, Brian D.

2006-01-01

The aim of this study was to establish the contribution of hip-mediated sensory feedback to spinal interneuronal circuits during dynamic conditions in people with incomplete spinal cord injury (SCI). Specifically, we investigated the effects of synergistic and antagonistic group I afferents on the soleus H-reflex during imposed sinusoidal hip movements. The soleus H-reflex was conditioned by stimulating the common peroneal nerve (CPN) at short (2, 3, and 4 ms) and long (80, 100, and 120 ms) conditioning test (C-T) intervals to assess the reciprocal and pre-synaptic inhibition of the soleus H-reflex, respectively. The soleus H-reflex was also conditioned by medial gastrocnemius (MG) nerve stimulation at C-T intervals ranging from 4 to 7 ms to assess changes in autogenic Ib inhibition during hip movement. Sinusoidal hip movements were imposed to the right hip joint at 0.2 Hz by the Biodex system while subjects were supine. The effects of sinusoidal hip movement on five leg muscles along with hip, knee, and ankle joint torques were also established during sensorimotor conditioning of the reflex. Phase-dependent modulation of antagonistic and synergistic muscle afferents was present during hip movement, with the reciprocal, pre-synaptic, and Ib inhibition to be significantly reduced during hip extension and reinforced during hip flexion. Reflexive muscle and joint torque responses – induced by the hip movement – were entrained to specific phases of hip movement. This study provides evidence that hip-mediated input acts as a controlling signal of pre- and post-alpha motoneuronal control of the soleus H-reflex. The expression of these spinal interneuronal circuits during imposed sinusoidal hip movements is discussed with respect to motor recovery in humans after SCI. PMID:16782072

Early development of the circumferential axonal pathway in mouse and chick spinal cord.

PubMed

Holley, J A

1982-03-10

The early development of the circumferential axonal pathway in the brachial and lumbar spinal cord of mouse and chick embryos was studied by scanning and transmission electron microscopy. The cellular processes which comprise this pathway grow in the transverse plane and along the lateral margin of the marginal zone (i.e., circumferentially oriented), as typified by the early embryonic commissural axons. The first formative event observed was in the ventrolateral margin of the primitive spinal cord ventricular zone. Cellular processes were found near the external limiting membrane that appeared to grow a variable distance either dorsally or ventrally. Later in development, presumptive motor column neurons migrated into the ventrolateral region, distal to these early circumferentially oriented processes. Concurrently, other circumferentially oriented perikarya and processes appeared along the dorsolateral margin. Due to their aligned sites of origin and parallel growth, the circumferential processes formed a more or less continuous line or pathway, which in about 10% of the scanned specimens could be followed along the entire lateral margin of the embryonic spinal cord. Several specimens later in development had two sets of aligned circumferential processes in the ventral region. Large numbers of circumferential axons were then found to follow the preformed pathway by fasciculation, after the primitive motor column had become established. Since the earliest circumferential processes appeared to differentiate into axons and were found nearly 24 hours prior to growth of most circumferential axons, their role in guidance as pioneering axons was suggested.

A 5000km2 data set along western Great Bahama Bank illustrates the dynamics of carbonate slope deposition

NASA Astrophysics Data System (ADS)

Schnyder, Jara S. D.; Jo, Andrew; Eberli, Gregor P.; Betzler, Christian; Lindhorst, Sebastian; Schiebel, Linda; Hebbeln, Dierk; Wintersteller, Paul; Mulder, Thierry; Principaud, Melanie

2014-05-01

An approximately 5000km2 hydroacoustic and seismic data set provides the high-resolution bathymetry map of along the western slope of Great Bahama Bank, the world's largest isolated carbonate platform. This large data set in combination with core and sediment samples, provides and unprecedented insight into the variability of carbonate slope morphology and the processes affecting the platform margin and the slope. This complete dataset documents how the interplay of platform derived sedimentation, distribution by ocean currents, and local slope and margin failure produce a slope-parallel facies distribution that is not governed by downslope gradients. Platform-derived sediments produce a basinward thinning sediment wedge that is modified by currents that change directions and strength depending on water depth and location. As a result, winnowing and deposition change with water depth and distance from the margin. Morphological features like the plunge pool and migrating antidunes are the result of currents flowing from the banktop, while the ocean currents produce contourites and drifts. These continuous processes are punctuated by submarine slope failures of various sizes. The largest of these slope failures produce several hundred of km2 of mass transport complexes and could generate tsunamis. Closer to the Cuban fold and thrust belt, large margin collapses pose an equal threat for tsunami generation. However, the debris from margin and slope failure is the foundation for a teeming community of cold-water corals.

Reflexive Research Ethics in Fetal Tissue Xenotransplantation Research

PubMed Central

Panikkar, Bindu; Smith, Natasha; Brown, Phil

2013-01-01

For biomedical research in which the only involvement of the human subject is the provision of tissue or organ samples, a blanket consent, i.e. consent to use the tissue for anything researchers wish to do, is considered by many to be adequate for legal and IRB requirements. Alternatively, a detailed informed consent provides patients or study participants with more thorough information about the research topic. We document here the beliefs and opinions of the research staff on informed consent and the discussion-based reflexive research ethics process that we employed in our fetal tissue xenotransplantion research on the impact of environmental exposures on fetal development. Reflexive research ethics entails the continued adjustment of research practice according to relational and reflexive understandings of what might be beneficent or harmful. Such reflexivity is not solely an individual endeavor, but rather a collective relationship between all actors in the research process. PMID:23074992

Charge state distribution and emission characteristics in a table top reflex discharge - Effect of ion confinement and electrons accelerated across the sheath

DOE PAGES

Kumar, Deepak; Englesbe, Alexander; Parman, Matthew; ...

2015-11-05

Tabletop reflex discharges in a Penning geometry have many applications including ion sources and eXtreme Ultra-Violet (XUV) sources. The presence of primary electrons accelerated across the cathode sheaths is responsible for the distribution of ion charge states and of the unusually high XUV brightness of these plasmas. Absolutely calibrated space resolved XUV spectra from a table top reflex discharge operating with Al cathodes and Ne gas are presented. The spectra are analyzed with a new and complete model for ion charge distribution in similar reflex discharges. The plasma in the discharge was found to have a density of ~10 18mmore » –3 with a significant fraction >0.01 of fast primary electrons. As a result, the implications of the new model on the ion states achievable in a tabletop reflex plasma discharge are also discussed.« less

Open and Distance Learning towards the Eradication of Illiteracy of the Tea-Garden Workers in Bangladesh: Problems and Prospects

ERIC Educational Resources Information Center

Roy, Sodip; Sattar, Md. Abdus

2015-01-01

Development of a society means the accumulation of improvement of all units of the society whatever it is small or large and important or less important. Needless to say that education goes identical with development. We have a large number of marginal people in different sector and region. Tea garden workers are one of them who are working…

Effect of Split-File Digital Workflow on Crown Margin Adaptation

DTIC Science & Technology

2017-03-30

you in your future publication/presentation efforts. LINDA STEEL -GOODWIN, Col, USAF, BSC Director, Clinical Investigations & Research Support...METHODS Multiple pilot studies were completed to define a working model with appropriate restoration settings ( cement gap 20 µm, extra cement gap 40...depressions for standardization. Right: Zirconia and e.max restorations had a cement gap (CG) = 20 µm ; extra cement gap (ECG) = 40 µm, and distance to

Reflexive Clitics in the Slavic and Romance Languages. A Comparative View from an Antipassive Perspective

ERIC Educational Resources Information Center

Medova, Lucie

2009-01-01

In this work, I offer a unified analysis of all the constructions that involve a reflexive clitic SE in Slavic and Romance languages. Next to canonical constructions, in which the reflexive clitic semantically identifies the two arguments of a transitive verb, cf. "John" SE "wash" means "John washes himself," there are constructions in which it is…

Leveraging Researcher Reflexivity to Consider a Classroom Event over Time: Reflexive Discourse Analysis of "What Counts"

ERIC Educational Resources Information Center

Anderson, Kate T.

2017-01-01

This article presents a reflexive and critical discourse analysis of classroom events that grew out of a cross-cultural partnership with a secondary school teacher in Singapore. I aim to illuminate how differences between researcher and teacher assumptions about what participation in classroom activities should look like came into high relief when…

Second Language Acquisition of Reflexive Verbs in Russian by L1 Speakers of English

ERIC Educational Resources Information Center

Alexieva, Petia Dimitrova

2012-01-01

This dissertation examines the process of acquisition of semantic classes of reflexive verbs (RVs) in Russian by L2 learners with a native language English. The purpose of this study is to bridge the gap between current linguistic knowledge and the pedagogical literature existing in English on reflexives in Russian. RVs are taught partially and…

Navigating the Tides of Change: Revisiting the Notion of Reflexivity in the Context of Social Learning for Transboundary Collective Experimentation

ERIC Educational Resources Information Center

Bastrup-Birk, Henriette; Wildemeersch, Danny

2011-01-01

Social learning theory in the context of multi-actor engagement tends to relate reflexivity primarily to critical questioning of theories-in-use. We argue that viewing suspensive dialogue and imaginative envisioning as additional stages of reflexivity will serve at least three purposes: prevent over-emphasis on instrumental rationality focusing on…

Role of stretch reflex in voluntary movements. [of human foot

NASA Technical Reports Server (NTRS)

Gottlieb, G. L.; Agarwal, G. C.

1975-01-01

The stretch reflex is often described as a spinal servomechanism, a device for assisting in the regulation of muscle length. Observation of the EMG response to mechanical interruption of voluntary movements fails to demonstrate a significant role for spinal reflexes at 40 msec latency. Two functional responses with latencies of 120 msec and 200 msec, implying supraspinal mediation, are observed.

[The role of the somatosensory cortex in the development of reflex analgesia].

PubMed

Kukushkin, M L; Reshetniak, V K; Durinian, R A

1986-06-01

The effects of reflex stimulation on the changes of nociception thresholds in animals before and after ablation of the somatosensory cortex were studied in behavioural experiments on adult cats. Electroacupuncture stimulation (EAP) was shown to increase nociception thresholds at all levels of the conventional scale. The ablation of both the first (S1) and the second (S2) somatosensory cortex led to EAP inefficiency at the side opposite to the ablation. Partial lesion of the lateral and suprasylvian gyri, used as control, did not affect the efficiency of reflex analgesia. It is concluded that somatosensory areas of the cortex, especially 2, are involved in reflex analgesia.

Do reflex seizures and spontaneous seizures form a continuum? - triggering factors and possible common mechanisms.

PubMed

Irmen, Friederike; Wehner, Tim; Lemieux, Louis

2015-02-01

Recent changes in the understanding and classification of reflex seizures have fuelled a debate on triggering mechanisms of seizures and their conceptual organization. Previous studies and patient reports have listed extrinsic and intrinsic triggers, albeit their multifactorial and dynamic nature is poorly understood. This paper aims to review literature on extrinsic and intrinsic seizure triggers and to discuss common mechanisms among them. Among self-reported seizure triggers, emotional stress is most frequently named. Reflex seizures are typically associated with extrinsic sensory triggers; however, intrinsic cognitive or proprioceptive triggers have also been assessed. The identification of a trigger underlying a seizure may be more difficult if it is intrinsic and complex, and if triggering mechanisms are multifactorial. Therefore, since observability of triggers varies and triggers are also found in non-reflex seizures, the present concept of reflex seizures may be questioned. We suggest the possibility of a conceptual continuum between reflex and spontaneous seizures rather than a dichotomy and discuss evidence to the notion that to some extent most seizures might be triggered. Copyright © 2014 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Extinction of the soleus H reflex induced by conditioning stimulus given after test stimulus.

PubMed

Hiraoka, Koichi

2002-02-01

To quantify the extinction of the soleus H reflex induced by a conditioning stimulus above the motor threshold to the post-tibial nerve applied 10-12 ms after a test stimulus (S2 method). Ten healthy subjects participated. The sizes of extinction induced by a test stimulus above the motor threshold (conventional method) and by the S2 method were measured. The size of the conditioned H reflex decreased as the intensity of the S2 conditioning stimulus increased. The decrease was less than that induced by the conventional method. The difference between the two methods correlated highly with the amount of orthodromically activated recurrent inhibition. When the S2 conditioning stimulus evoked an M wave that was roughly half of the maximum M wave, the decrease in the size of the conditioned H reflex depended on the size of the unconditioned H reflex. The S2 method allows us to observe extinction without changing the intensity of the test stimulus. The amount of the extinction depends partially on the size of the unconditioned H reflex. The difference in the sizes of extinction between the S2 and conventional methods should relate to recurrent inhibition.

Could the Use of Acoustic Reflexes Prior to Administering Distortion Product Otoacoustic Emissions (DPOAEs) Affect the Results of DPOAEs?

PubMed

Garrette, Rachel; Jones, Alisha L; Wilson, Martha W

2018-05-15

The purpose of this study is to investigate whether acoustic reflex threshold testing before administration of distortion product otoacoustic emissions can affect the results of the distortion product otoacoustic emissions testing using an automated protocol. Fifteen young adults with normal hearing ranging in age from 19 to 25 years participated in the study. All participants had clear external ear canals and normal Jerger Type A tympanograms and had passed a hearing screening. Testing was performed using the Interacoustics Titan acoustic reflex threshold and distortion product otoacoustic emissions protocol. Participants underwent baseline distortion product otoacoustic emissions. A paired-samples t test was conducted for both the right and left ears to assess within-group differences between baseline distortion product otoacoustic emissions and repeated distortion product otoacoustic emissions measures. No significant differences were found in distortion product otoacoustic emission measures following administration of acoustic reflexes. The use of a protocol when using an automated system that includes both acoustic reflexes and distortion product otoacoustic emissions is important. Overall, presentation of acoustic reflexes prior to measuring distortion product otoacoustic emission did not affect distortion product otoacoustic emission results; therefore, test sequence can be modified as needed.

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

PubMed

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 motor excitability has not been fully understood. We found that, during orthodontic treatment, trigeminal motor excitability is acutely increased and then decreased in a week. Because alteration of trigeminal motor function can be evaluated quantitatively by jaw-opening reflex excitability, the present animal model may be useful to search for alternative approaches to attenuate orthodontic pain. Copyright © 2017 the American Physiological Society.

A novel reflex cough testing device.

PubMed

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 < 0.0001), while that of group B was significantly lower than that of the control group (p < 0.0001). The time until the cough 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 < 0.001, B: p < 0.001), but there was no significant difference between groups A and B (p = 0.0907). Our newly developed device can easily and simultaneously measure the time until the cough reflex and the strength of involuntary coughs for assessment of patients at risk of aspiration pneumonia.

A Flight Examination of Operating Problems of V/STOL Aircraft in STOL-Type Landing and Approach

NASA Technical Reports Server (NTRS)

Innis, Robert C.; Quigley, Hervey C.

1961-01-01

A flight investigation has been conducted using a large twin-engine cargo aircraft to isolate the problems associated with operating propeller-driven aircraft in the STOL speed range where appreciable engine power is used to augment aerodynamic lift. The problems considered would also be representative of those of a large overloaded VTOL aircraft operating in an STOL manner with comparable thrust-to-weight ratios. The study showed that operation at low approach speeds was compromised by the necessity of maintaining high thrust to generate high lift and yet achieving the low lift-drag ratios needed for steep descents. The useable range of airspeed and flight path angle was limited by the pilot's demand for a positive climb margin at the approach speed, a suitable stall margin, and a control and/or performance margin for one engine inoperative. The optimum approach angle over an obstacle was found to be a compromise between obtaining the shortest air distance and the lowest touchdown velocity. In order to realize the greatest low-speed potential from STOL designs, the stability and control characteristics must be satisfactory.

Asynchronous ice lobe retreat and glacial Lake Bascom: Deglaciation of the Hoosic and Vermont valleys, southwestern Vermont

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

Small, E.; Desimone, D.

Deglaciation of the Hoosic River drainage basin in southwestern Vermont was more complex than previously described. Detailed surficial mapping, stratigraphic relationships, and terrace levels/delta elevations reveal new details in the chronology of glacial Lake Bascom: (1) a pre-Wisconsinan proglacial lake was present in a similar position to Lake Bascom as ice advanced: (2) the northern margin of 275m (900 ft) glacial Lake Bascom extended 10 km up the Vermont Valley; (3) the 215m (705 ft) Bascom level was stable and long lived; (4) intermediate water planes existed between 215m and 190m (625 ft) levels; and (5) a separate ice tonguemore » existed in Shaftsbury Hollow damming a small glacial lake, here named glacial Lake Emmons. This information is used to correlate ice margins to different lake levels. Distance of ice margin retreat during a lake level can be measured. Lake levels are then used as control points on a Lake Bascom relative time line to compare rate of retreat of different ice tongues. Correlation of ice margins to Bascom levels indicates ice retreat was asynchronous between nearby tongues in southwestern Vermont. The Vermont Valley ice tongue retreated between two and four times faster than the Hoosic Valley tongue during the Bascom 275m level. Rate of retreat of the Vermont Valley tongue slowed to one-half of the Hoosic tongue during the 215m--190m lake levels. Factors responsible for varying rates of retreat are subglacial bedrock gradient, proximity to the Hudson-Champlain lobe, and the presence of absence of a calving margins. Asynchronous retreat produced splayed ice margins in southwestern Vermont. Findings from this study do not support the model of parallel, synchronous retreat proposed by many workers for this region.« less

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

PubMed

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.

Losing touch: age-related changes in plantar skin sensitivity, lower limb cutaneous reflex strength, and postural stability in older adults

PubMed Central

Peters, Ryan M.; McKeown, Monica D.; Carpenter, Mark G.

2016-01-01

Age-related changes in the density, morphology, and physiology of plantar cutaneous receptors negatively impact the quality and quantity of balance-relevant information arising from the foot soles. Plantar perceptual sensitivity declines with age and may predict postural instability; however, alteration in lower limb cutaneous reflex strength may also explain greater instability in older adults and has yet to be investigated. We replicated the age-related decline in sensitivity by assessing monofilament and vibrotactile (30 and 250 Hz) detection thresholds near the first metatarsal head bilaterally in healthy young and older adults. We additionally applied continuous 30- and 250-Hz vibration to drive mechanically evoked reflex responses in the tibialis anterior muscle, measured via surface electromyography. To investigate potential relationships between plantar sensitivity, cutaneous reflex strength, and postural stability, we performed posturography in subjects during quiet standing without vision. Anteroposterior and mediolateral postural stability decreased with age, and increases in postural sway amplitude and frequency were significantly correlated with increases in plantar detection thresholds. With 30-Hz vibration, cutaneous reflexes were observed in 95% of young adults but in only 53% of older adults, and reflex gain, coherence, and cumulant density at 30 Hz were lower in older adults. Reflexes were not observed with 250-Hz vibration, suggesting this high-frequency cutaneous input is filtered out by motoneurons innervating tibialis anterior. Our findings have important implications for assessing the risk of balance impairment in older adults. PMID:27489366

Volitional control of reflex cough

PubMed Central

Bolser, Donald C.; Davenport, Paul W.

2012-01-01

Multiple studies suggest a role for the cerebral cortex in the generation of reflex cough in awake humans. Reflex cough is preceded by detection of an urge to cough; strokes specifically within the cerebral cortex can affect parameters of reflex cough, and reflex cough can be voluntarily suppressed. However, it is not known to what extent healthy, awake humans can volitionally modulate the cough reflex, aside from suppression. The aims of this study were to determine whether conscious humans can volitionally modify their reflexive cough and, if so, to determine what parameters of the cough waveform and corresponding muscle activity can be modified. Twenty adults (18–40 yr, 4 men) volunteered for study participation and gave verbal and written informed consent. Participants were seated and outfitted with a facemask and pneumotacograph, and two surface EMG electrodes were positioned over expiratory muscles. Capsaicin (200 μM) was delivered via dosimeter and one-way (inspiratory) valve attached to a side port between the facemask and pneumotachograph. Cough airflow and surface EMG activity were recorded across tasks including 1) baseline, 2) small cough (cough smaller or softer than normal), 3) long cough (cough longer or louder than normal), and 4) not cough (alternative behavior). All participants coughed in response to 200 μM capsaicin and were able to modify the cough. Variables exhibiting changes include those related to the peak airflow during the expiratory phase. Results demonstrate that it is possible to volitionally modify cough motor output characteristics. PMID:22492938

Sexually stimulated testosterone release in male mice (Mus musculus): roles of genotype and sexual arousal.

PubMed

James, Peter J; Nyby, John G; Saviolakis, George A

2006-09-01

In virtually every mammalian species examined, some males exhibit reflexive testosterone release upon encountering a novel female (or female-related stimulus). At the same time, not every individual male (or every published study) provides evidence for reflexive testosterone release. Four experiments using house mice (Mus musculus) examined the hypothesis that both the male's genotype and his degree of sexual arousal (as indexed by ultrasonic mating calls) are related to such variability. In Experiment 1, CF-1 males exhibited reflexive testosterone elevations 30 min after encountering female urine. CK males, on the other hand, did not exhibit testosterone elevations 20, 30, 50, 60, or 80 min after encountering female urine (Experiments 1 and 2) suggesting this strain incapable of reflexive release. In Experiment 3, we measured both mating calls and reflexive testosterone release in response to female urine in CF-1 and CK males. Most males of both strains called vigorously to female urine but not to water. But, only CF-1 males exhibited significant testosterone elevations to female urine. In Experiment 4, DBA/2J males called vigorously to females followed by testosterone elevations 30 min later. The first 3 experiments support the hypothesis that male genotype is an important variable underlying mammalian reflexive testosterone release. Statistically significant correlations between mating calls in the first minute after stimulus exposure and testosterone elevations 30 min later (Experiments 3 and 4) support the hypothesis that, in capable males, reflexive testosterone release is related to the male's initial sexual arousal.

Effects of reflex-based self-defence training on police performance in simulated high-pressure arrest situations.

PubMed

Renden, Peter G; Savelsbergh, Geert J P; Oudejans, Raôul R D

2017-05-01

We investigated the effects of reflex-based self-defence training on police performance in simulated high-pressure arrest situations. Police officers received this training as well as a regular police arrest and self-defence skills training (control training) in a crossover design. Officers' performance was tested on several variables in six reality-based scenarios before and after each training intervention. Results showed improved performance after the reflex-based training, while there was no such effect of the regular police training. Improved performance could be attributed to better communication, situational awareness (scanning area, alertness), assertiveness, resolution, proportionality, control and converting primary responses into tactical movements. As officers trained complete violent situations (and not just physical skills), they learned to use their actions before physical contact for de-escalation but also for anticipation on possible attacks. Furthermore, they learned to respond against attacks with skills based on their primary reflexes. The results of this study seem to suggest that reflex-based self-defence training better prepares officers for performing in high-pressure arrest situations than the current form of police arrest and self-defence skills training. Practitioner Summary: Police officers' performance in high-pressure arrest situations improved after a reflex-based self-defence training, while there was no such effect of a regular police training. As officers learned to anticipate on possible attacks and to respond with skills based on their primary reflexes, they were better able to perform effectively.

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

PubMed

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.

Compensatory increase of the cervico-ocular reflex with age in healthy humans

PubMed Central

Kelders, W P A; Kleinrensink, G J; van der Geest, J N; Feenstra, L; de Zeeuw, C I; Frens, M A

2003-01-01

The cervico-ocular reflex (COR) is an ocular stabilization reflex that is elicited by rotation of the neck. It works in conjunction with the vestibulo-ocular reflex (VOR) and the optokinetic reflex (OKR) in order to prevent visual slip over the retina due to self-motion. The gains of the VOR and OKR are known to decrease with age. We have investigated whether the COR, a reflexive eye movement elicited by rotation of the neck, shows a compensatory increase and whether a synergy exists between the COR and the other ocular stabilization reflexes. In the present study 35 healthy subjects of varying age (20–86 years) were rotated in the dark in a trunk-to-head manner (the head fixed in spaced with the body passively rotated under it) at peak velocities between 2.1 and 12.6 deg s−1 as a COR stimulus. Another 15 were subjected to COR, VOR and OKR stimuli at frequencies between 0.04 and 0.1 Hz. Three subjects participated in both tests. The position of the eyes was recorded with an infrared recording technique. We found that the COR-gain increases with increasing age and that there is a significant covariation between the gains of the VOR and COR, meaning that when VOR increases, COR decreases and vice versa. A nearly constant phase lag between the COR and the VOR of about 25 deg existed at all stimulus frequencies. PMID:12949226

Three-dimensional vestibular eye and head reflexes of the chameleon: characteristics of gain and phase and effects of eye position on orientation of ocular rotation axes during stimulation in yaw direction.

PubMed

Haker, H; Misslisch, H; Ott, M; Frens, M A; Henn, V; Hess, K; Sándor, P S

2003-07-01

We investigated gaze-stabilizing reflexes in the chameleon using the three-dimensional search-coil technique. Animals were rotated sinusoidally around an earth-vertical axis under head-fixed and head-free conditions, in the dark and in the light. Gain, phase and the influence of eye position on vestibulo-ocular reflex rotation axes were studied. During head-restrained stimulation in the dark, vestibulo-ocular reflex gaze gains were low (0.1-0.3) and phase lead decreased with increasing frequencies (from 100 degrees at 0.04 Hz to < 30 degrees at 1 Hz). Gaze gains were larger during stimulation in the light (0.1-0.8) with a smaller phase lead (< 30 degrees) and were close to unity during the head-free conditions (around 0.6 in the dark, around 0.8 in the light) with small phase leads. These results confirm earlier findings that chameleons have a low vestibulo-ocular reflex gain during head-fixed conditions and stimulation in the dark and higher gains during head-free stimulation in the light. Vestibulo-ocular reflex eye rotation axes were roughly aligned with the head's rotation axis and did not systematically tilt when the animals were looking eccentrically, up- or downward (as predicted by Listing's Law). Therefore, vestibulo-ocular reflex responses in the chameleon follow a strategy, which optimally stabilizes the entire retinal images, a result previously found in non-human primates.

Effect of Maturation of the Magnitude of Mechanosensitive and Chemosensitive Reflexes in the Premature Human Esophagus

PubMed Central

Jadcherla, Sudarshan Rao; Hoffmann, Raymond G.; Shaker, Reza

2014-01-01

Objectives To investigate the effect of esophageal mechanosensitive and chemosensitive stimulation on the magnitude and recruitment of peristaltic reflexes and upper esophageal sphincter (UES)-contractile reflex in premature infants. Study design Esophageal manometry and provocation testing were performed in the same 18 neonates at 33 and 36 weeks postmenstrual age (PMA). Mechanoreceptor and chemoreceptor stimulation were performed using graded volumes of air, water, and apple juice (pH 3.7), respectively. The frequency and magnitude of the resulting esophago-deglutition response (EDR) or secondary peristalsis (SP), and esophago-UES-contractile reflex (EUCR) were quantified. Results Threshold volumes to evoke EDR, SP, or EUCR were similar. The recruitment and magnitude of SP and EUCR increased with volume increments of air and water in either study (P < .05). However, apple juice infusions resulted in increased recruitment of EDR in the 33 weeks group (P < .05), and SP in the 36 weeks group (P < .05). The magnitude of EUCR was also volume responsive (all media, P < .05), and significant differences between media were noted (P < .05). At maximal stimulation (1 mL, all media), sensory-motor characteristics of peristaltic and EUCR reflexes were different (P < .05) between media and groups. Conclusions Mechano- and chemosensitive stimuli evoke volume-dependent specific peristaltic and UES reflexes at 33 and 36 weeks PMA. The recruitment and magnitude of these reflexes are dependent on the physicochemical properties of the stimuli in healthy premature infants. PMID:16860132

Lower Amplitude of the Hoffmann Reflex in Women With Patellofemoral Pain: Thinking Beyond Proximal, Local, and Distal Factors.

PubMed

de Oliveira Silva, Danilo; Magalhães, Fernando Henrique; Faria, Nathálie Clara; Pazzinatto, Marcella Ferraz; Ferrari, Deisi; Pappas, Evangelos; de Azevedo, Fábio Mícolis

2016-07-01

To investigate whether vastus medialis (VM) Hoffmann reflexes (H-reflexes) differ on the basis of the presence or absence of patellofemoral pain (PFP) and to assess the capability of VM H-reflex measurements in accurately discriminating between women with and without PFP. Cross-sectional study. Laboratory of biomechanics and motor control. Women (N=30) aged 18 to 35 years were recruited, consisting of 2 groups: women with PFP (n=15) and asymptomatic controls (n=15). Not applicable. Maximum evoked responses were obtained by electrical stimulation applied to the femoral nerve, and peak-to-peak amplitudes of maximal Hoffmann reflex (Hmax) and maximal motor wave (Mmax) ratios were calculated. Independent samples t tests were performed to identify differences between groups, and a receiver operating characteristic curve was constructed to assess the discriminatory capability of VM H-reflex measurements. VM Hmax/Mmax ratios were significantly lower in participants with PFP than in pain-free participants (P=.007). In addition, the VM Hmax/Mmax ratios presented large and balanced discriminatory capability values (sensitivity, 73%; specificity, 67%). This study is the first to show that VM H-reflexes are lower in women with PFP than in asymptomatic controls. Therefore, increasing the excitation of the spinal cord in PFP participants may be essential to maintaining the gains acquired during the rehabilitation programs. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

[Measuring the effect of eyeglasses on determination of squint angle with Purkinje reflexes and the prism cover test].

PubMed

Barry, J C; Backes, A

1998-04-01

The alternating prism and cover test is the conventional test for the measurement of the angle of strabismus. The error induced by the prismatic effect of glasses is typically about 27-30%/10 D. Alternatively, the angle of strabismus can be measured with methods based on Purkinje reflex positions. This study examines the differences between three such options, taking into account the influence of glasses. The studied system comprised the eyes with or without glasses, a fixation object and a device for recording the eye position: in the case of the alternate prism and cover test, a prism bar was required; in the case of a Purkinje reflex based device, light sources for generation of reflexes and a camera for the documentation of the reflex positions were used. Measurements performed on model eyes and computer ray traces were used to analyze and compare the options. When a single corneal reflex is used, the misalignment of the corneal axis can be measured; the error in this measurement due to the prismatic effect of glasses was 7.6%/10 D, the smallest found in this study. The individual Hirschberg ratio can be determined by monocular measurements in three gaze directions. The angle of strabismus can be measured with Purkinje reflex based methods if the fundamental differences between these methods and the alternate prism and cover test, and if the influence of glasses and other sources of error are accounted for.

[Treatment with sympathetic intravenous block with reserpine in work-related reflex sympathetic dystrophy].

PubMed

Morros, C; Cedo, F

1994-01-01

To assess the results obtained in treatment of sympathetic reflex dystrophy by sympathetic endovenous blockades with reserpine in working patients. We reviewed 170 diagnoses of sympathetic reflex dystrophy in 165 patients. One hundred seven were located in the foot, 13 were in the knee and 50 were in the hand. All were treated once a week for 3 weeks with local sympathetic endovenous blocks with reserpine (1 mg in the upper extremity and 1.5 mg in the lower extremity). We analyzed the location, etiology, course, X-rays, gammagrams, psychological state, other treatments, associated conditions, number of blocks received and side effects. The results were classified as excellent, good, fair and nil. We particularly reviewed sympathetic reflex dystrophy associated to Colles' fractures. Five hundred forty endovenous sympathetic blocks with reserpine were performed. Results obtained were excellent in 57 (34%) patients, good in 77 (45%), fair in 29 (17%) and nil in 7 (4%). Sympathetic reflex dystrophy leads to loss of 215 +/- 91 working days. In patients with Colles' fracture without sympathetic reflex dystrophy the loss is 96 +/- 31 days, although this period lengthens to 115 +/- 15 days if the two conditions are associated in stage I and to loss of 193 +/- 71 days if the association is in stage II. Results of treating sympathetic reflex dystrophy with sympathetic endovenous blocks with reserpine are satisfactory, particularly when diagnosis and treatment are early, clearly demonstrating the usefulness of this technique in workplace medicine.

Reflex epileptic mechanisms in humans: Lessons about natural ictogenesis.

PubMed

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.

Respiratory reflexes in response to nasal administration of halothane to anesthetized, spontaneously breathing dogs.

PubMed

Mutoh, T; Kanamaru, A; Tsubone, H; Nishimura, R; Sasaki, N

2000-03-01

To characterize and determine the sensory innervation of respiratory reflexes elicited by nasal administration of halothane to dogs. 10 healthy Beagles. Dogs underwent permanent tracheostomy and, 2 to 3 weeks later, were anesthetized with thiopental and alpha-chloralose administered IV. The nasal passages were functionally isolated so that halothane could be administered to the nasal passages while dogs were breathing 100% O2 via the tracheostomy. Respiratory reflexes in response to administration of halothane at concentrations of 1.25, 1.75, and 2.5 times the minimum alveolar concentration (MAC), and 5% (administered in 100% O2 at a flow rate of 5 L/min) were recorded. Reflexes in response to administration of 5% halothane were also recorded following transection of the infraorbital nerve, transection of the caudal nasal nerve, and nasal administration of lidocaine. Nasal administration of halothane induced an inhibition of breathing characterized by a dose-dependent increase in expiratory time and a resultant decrease in expired volume per unit time. Effects were noticeable immediately after the onset of halothane administration and lasted until its cessation. Reflex responses to halothane administration were attenuated by transection of the caudal nasal nerve and by nasal administration of lidocaine, but transection of the infraorbital nerve had no effect. Nasal administration of halothane at concentrations generally used for mask induction of anesthesia induces reflex inhibition of breathing. Afferent fibers in the caudal nasal nerve appear to play an important role in the reflex inhibition of breathing induced by halothane administration.

Spasm of accommodation associated with closed head trauma.

PubMed

Chan, R V Paul; Trobe, Jonathan D

2002-03-01

Spasm of accommodation, creating pseudomyopia, is generally associated with miosis and excess convergence as part of spasm of the near reflex. It may also exist as an isolated entity, usually attributed to psychogenic causes. We present six cases of accommodative spasm associated with closed head injury. All patients were male, ranging in age between 16 and 37 years. The degree of pseudomyopia, defined as the difference between manifest and cycloplegic refraction, was 1.5 to 2 diopters. A 3-year trial of pharmacologically induced cycloplegia in one patient did not lead to reversal of the spasm when the cycloplegia was stopped. All patients required the manifest refraction to see clearly at distance. The pseudomyopia endured for at least 7 years following head trauma. This phenomenon may represent traumatic activation or disinhibition of putative brain stem accommodation centers in young individuals.

Biogeography and Potential Exchanges Among the Atlantic Equatorial Belt Cold-Seep Faunas

PubMed Central

Olu, Karine; Cordes, Erik E.; Fisher, Charles R.; Brooks, James M.; Sibuet, Myriam; Desbruyères, Daniel

2010-01-01

Like hydrothermal vents along oceanic ridges, cold seeps are patchy and isolated ecosystems along continental margins, extending from bathyal to abyssal depths. The Atlantic Equatorial Belt (AEB), from the Gulf of Mexico to the Gulf of Guinea, was one focus of the Census of Marine Life ChEss (Chemosynthetic Ecosystems) program to study biogeography of seep and vent fauna. We present a review and analysis of collections from five seep regions along the AEB: the Gulf of Mexico where extensive faunal sampling has been conducted from 400 to 3300m, the Barbados accretionary prism, the Blake ridge diapir, and in the Eastern Atlantic from the Congo and Gabon margins and the recently explored Nigeria margin. Of the 72 taxa identified at the species level, a total of 9 species or species complexes are identified as amphi-Atlantic. Similarity analyses based on both Bray Curtis and Hellinger distances among 9 faunal collections, and principal component analysis based on presence/absence of megafauna species at these sites, suggest that within the AEB seep megafauna community structure is influenced primarily by depth rather than by geographic distance. Depth segregation is observed between 1000 and 2000m, with the middle slope sites either grouped with those deeper than 2000m or with the shallower sites. The highest level of community similarity was found between the seeps of the Florida escarpment and Congo margin. In the western Atlantic, the highest degree of similarity is observed between the shallowest sites of the Barbados prism and of the Louisiana slope. The high number of amphi-atlantic cold-seep species that do not cluster according to biogeographic regions, and the importance of depth in structuring AEB cold-seep communities are the major conclusions of this study. The hydrothermal vent sites along the Mid Atlantic Ridge (MAR) did not appear as “stepping stones” for dispersal of the AEB seep fauna, however, the south MAR and off axis regions should be further explored to more fully test this hypothesis. PMID:20700528

The Tail-Elicited Tail Withdrawal Reflex of "Aplysia" Is Mediated Centrally at Tail Sensory-Motor Synapses and Exhibits Sensitization across Multiple Temporal Domains

ERIC Educational Resources Information Center

Philips, Gary T.; Sherff, Carolyn M.; Menges, Steven A.; Carew, Thomas J.

2011-01-01

The defensive withdrawal reflexes of "Aplysia californica" have provided powerful behavioral systems for studying the cellular and molecular basis of memory formation. Among these reflexes the (T-TWR) has been especially useful. In vitro studies examining the monosynaptic circuit for the T-TWR, the tail sensory-motor (SN-MN) synapses, have…

Ethical Mindfulness and Reflexivity: Managing a Research Relationship with Children and Young People in a 14-Year Qualitative Longitudinal Research (QLR) Study

ERIC Educational Resources Information Center

Warin, Jo

2011-01-01

This article draws on the articulation of a value for reflexivity that has accumulated within qualitative methods debates in the past decade. It demonstrates how reflexivity is interwoven with the concept of ethical mindfulness. The argument has developed from a consideration of the ethical dilemmas that were a salient aspect of an ongoing…

Discontinuation of reflex testing of stool samples for vancomycin-resistant enterococci resulted in increased prevalence.

PubMed

Bodily, Mandy; McMullen, Kathleen M; Russo, Anthony J; Kittur, Nupur D; Hoppe-Bauer, Joan; Warren, David K

2013-08-01

Discontinuation of reflex testing of stool submitted for Clostridium difficile testing for vancomycin-resistant enterococci (VRE) led to an increase in the number of patients with healthcare-associated VRE bacteremia and bacteriuria (0.21 vs 0.36 cases per 1,000 patient-days; P<.01). Cost-benefit analysis showed reflex screening and isolation of VRE reduced hospital costs.

Reflex Responses to Ligament Loading: Implications for Knee Joint Stability

DTIC Science & Technology

2001-10-25

white noise approach", Prentice-Hall".:, 1978. [15] B. Grenfield and B. Wyke, "Reflex innervation of the temporo - mandibular joint .". Nature. 211(52...selective, depending on the magnitude of the angular perturbation. Keywords - Reflex, Periarticular tissue afferents, Joint stability I...INTRODUCTION Traditionally, joint stability has been considered to be purely mechanical in origin, with little or no consideration of neuromuscular

Reflex responses of paraspinal muscles to tapping

PubMed Central

Dimitrijevic, M R; Gregoric, M R; Sherwood, A M; Spencer, W A

1980-01-01

Erector spinae reflex studies in healthy subjects revealed two responses: a 12·0±1·6 ms latency, oligosynaptic response, and a 30 to 50 ms latency response with polysynaptic reflex characteristics. There was a silent period after the first and second responses. The effect of limb position, trunk, neck, postural changes, Jendrassik manoeuvre and vibration on both responses were also evaluated. PMID:7217957

Reflexes from pulmonary arterial baroreceptors in dogs: interaction with carotid sinus baroreceptors

PubMed Central

Moore, Jonathan P; Hainsworth, Roger; Drinkhill, Mark J

2011-01-01

Abstract In contrast to the reflex vasodilatation occurring in response to stimulation of baroreceptors in the aortic arch, carotid sinuses and coronary arteries, stimulation of receptors in the wall of pulmonary arteries results in reflex systemic vasoconstriction. It is rare for interventions to activate only one reflexogenic region, therefore we investigated how these two types of reflexes interact. In anaesthetized dogs connected to cardiopulmonary bypass, reflexogenic areas of the carotid sinuses, aortic arch and coronary arteries and the pulmonary artery were subjected to independently controlled pressures. Systemic perfusion pressure (SPP) measured in the descending aorta (constant flow) provided an index of systemic vascular resistance. In other experiments, sympathetic efferent neural activity was recorded in fibres dissected from the renal nerve (RSNA). Physiological increases in pulmonary arterial pressure (PAP) induced significant increases in SPP (+39.1 ± 10.4 mmHg) and RSNA (+17.6 ± 2.2 impulses s−1) whereas increases in carotid sinus pressure (CSP) induced significant decreases in SPP (−42.6 ± 10.8 mmHg) and RSNA (−42.8 ± 18.2 impulses s−1) (P < 0.05 for each comparison; paired t test). To examine possible interactions, PAP was changed at different levels of CSP in both studies. With CSP controlled at 124 ± 2 mmHg, the threshold, ‘set point’ and saturation pressures of the PAP–SPP relationship were higher than those with CSP at 60 ± 1 mmHg; this rightward shift was associated with a significant decrease in the reflex gain. Similarly, increasing CSP produced a rightward shift of the PAP–RSNA relationship, although the effect on reflex gain was inconsistent. Furthermore, the responses to changes in CSP were influenced by setting PAP at different levels; increasing the level of PAP from 5 ± 1 to 33 ± 3 mmHg significantly increased the set point and threshold pressures of the CSP–SPP relationship; the reflex gain was not affected. These results indicate the existence of interaction between pulmonary arterial and carotid sinus baroreceptor reflexes; physiological and pathological states that alter the stimulus to one may alter the reflex responses from the other. PMID:21690195

Morphometry and CT measurements of useful bony landmarks of skull base.

PubMed

Ray, Biswabina; Rajagopal, K V; Rajesh, T; Gayathri, B M V; D'Souza, A S; Swarnashri, J V; Saxena, Alok

2011-01-01

Aim of this study was to determine the distance between Henle's spine (HS) on the temporal bone to the clinically important bony landmarks on the dry skulls that will act as a guide in various surgical procedures on skull base. Distances from the head of malleus (HOM) to surgically relevant landmarks were also studied on CT images. Thirty-nine adult preserved dry skulls were studied bilaterally. The parapetrosal triangle bounded by spinopterygoidal, bispinal and the midsagittal lines was identified. The location of the HS and its distance from the various important anatomical structures were measured. In addition, five CT images, where distances from the HOM to various anatomical landmarks were measured. The mean and range of distances from the HS to various important anatomical landmarks on the spinopterygoidal line, bispinal line and in the parapetrosal triangle were tabulated. The mean and range of CT-based measurements of distances from HOM to other anatomical landmarks were also noted. The knowledge of unvarying relationship of the HS and the HOM to the various structures of the skull would assume significance while planning surgeries around the temporal bone by guiding the direction and degree of bone removal. Statistical differences between the two genders showed significant difference only in the distance between the HS to the medial margin of the external orifice of carotid canal. Therefore, these landmarks can also be applied as references for various surgeries of middle cranial fossa, as well as transpetrosal and transmastoid approaches.

Relationship between distance from major roads and adolescent health in Japan.

PubMed

Miyake, Yoshihiro; Yura, Akiko; Iki, Masayuki

2002-11-01

A relationship between distance from major roads and the prevalence of allergic disorders and general symptoms among junior high school students was assessed, separating the effects of distance of residence and school from the roads. Study subjects were 5,652 students aged 12 to 15 years. This study used diagnostic criteria from the International Study of Asthma and Allergies in Childhood. The questionnaire also asked about symptoms of headache, stomachache, tiredness, and cough and the shortest distance from residence to major roads. Distance from school to the nearest major road was measured on a map. Adjustment was made for gender, grade, the number of older siblings, smoking in the household, and maternal history of allergy. A shorter distance between residence and major roads was associated with an increased prevalence of headache, stomachache, tiredness, and cough. There was a marginally significant positive association between residence facing major roads and the prevalence of allergic rhinoconjunctivitis. Residence within 100 m of major roads showed a tendency for a positive relationship with the prevalence of wheeze and atopic dermatitis. There was no apparent relationship between distance of school from major roads and allergic disorders or the general symptoms. The findings suggest that proximity of residence, not school, to major roads may be associated with an increased prevalence of allergic disorders, headache, stomachache, and tiredness among Japanese adolescents. Further investigations with more precise and detailed exposure and health outcome measurements are needed to corroborate the relationship between traffic related factors and allergic disorders and general symptoms.

A statistical model for analyzing the rotational error of single isocenter for multiple targets technique.

PubMed

Chang, Jenghwa

2017-06-01

To develop a statistical model that incorporates the treatment uncertainty from the rotational error of the single isocenter for multiple targets technique, and calculates the extra PTV (planning target volume) margin required to compensate for this error. The random vector for modeling the setup (S) error in the three-dimensional (3D) patient coordinate system was assumed to follow a 3D normal distribution with a zero mean, and standard deviations of σ x , σ y , σ z . It was further assumed that the rotation of clinical target volume (CTV) about the isocenter happens randomly and follows a three-dimensional (3D) independent normal distribution with a zero mean and a uniform standard deviation of σ δ . This rotation leads to a rotational random error (R), which also has a 3D independent normal distribution with a zero mean and a uniform standard deviation of σ R equal to the product of σδπ180 and dI⇔T, the distance between the isocenter and CTV. Both (S and R) random vectors were summed, normalized, and transformed to the spherical coordinates to derive the Chi distribution with three degrees of freedom for the radial coordinate of S+R. PTV margin was determined using the critical value of this distribution for a 0.05 significance level so that 95% of the time the treatment target would be covered by the prescription dose. The additional PTV margin required to compensate for the rotational error was calculated as a function of σ R and dI⇔T. The effect of the rotational error is more pronounced for treatments that require high accuracy/precision like stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT). With a uniform 2-mm PTV margin (or σ x = σ y = σ z = 0.715 mm), a σ R = 0.328 mm will decrease the CTV coverage probability from 95.0% to 90.9%, or an additional 0.2-mm PTV margin is needed to prevent this loss of coverage. If we choose 0.2 mm as the threshold, any σ R > 0.328 mm will lead to an extra PTV margin that cannot be ignored, and the maximal σ δ that can be ignored is 0.45° (or 0.0079 rad ) for dI⇔T = 50 mm or 0.23° (or 0.004 rad ) for dI⇔T = 100 mm. The rotational error cannot be ignored for high-accuracy/-precision treatments like SRS/SBRT, particularly when the distance between the isocenter and target is large. © 2017 American Association of Physicists in Medicine.

Ocular screening tests of elementary school children

NASA Technical Reports Server (NTRS)

Richardson, J.

1983-01-01

This report presents an analysis of 507 abnormal retinal reflex images taken of Huntsville kindergarten and first grade students. The retinal reflex images were obtained by using an MSFC-developed Generated Retinal Reflex Image System (GRRIS) photorefractor. The system uses a 35 mm camera with a telephoto lens with an electronic flash attachment. Slide images of the eyes were examined for abnormalities. Of a total of 1835 students screened for ocular abnormalities, 507 were found to have abnormal retinal reflexes. The types of ocular abnormalities detected were hyperopia, myopia, astigmatism, esotropia, exotropia, strabismus, and lens obstuctions. The report shows that the use of the photorefractor screening system is an effective low-cost means of screening school children for abnormalities.

The origin of Woltman's sign of myxoedema.

PubMed

Burkholder, David B; Klaas, James P; Kumar, Neeraj; Boes, Christopher J

2013-09-01

Woltman's sign of myxoedema, named after Henry Woltman in 1956, is the delayed relaxation phase of the muscle stretch reflex in patients with myxoedema. Although a change in these reflexes was mentioned as being clinically evident possibly as early as the 1870s, no formal description was published until 1924 when William Calvert Chaney objectively quantified the change. Woltman was involved in training Chaney, and it has been proposed that he guided Chaney's study of these reflexes. Despite the attachment of Woltman's name to the eponym, little evidence exists that directly links him to the first objective study of the muscle stretch reflex in myxoedema performed by Chaney. Copyright © 2013 Elsevier Ltd. All rights reserved.

Device for rapid quantification of human carotid baroreceptor-cardiac reflex responses

NASA Technical Reports Server (NTRS)

Sprenkle, J. M.; Eckberg, D. L.; Goble, R. L.; Schelhorn, J. J.; Halliday, H. C.

1986-01-01

A new device has been designed, constructed, and evaluated to characterize the human carotid baroreceptor-cardiac reflex response relation rapidly. This system was designed for study of reflex responses of astronauts before, during, and after space travel. The system comprises a new tightly sealing silicon rubber neck chamber, a stepping motor-driven electrodeposited nickel bellows pressure system, capable of delivering sequential R-wave-triggered neck chamber pressure changes between +40 and -65 mmHg, and a microprocessor-based electronics system for control of pressure steps and analysis and display of responses. This new system provokes classic sigmoid baroreceptor-cardiac reflex responses with threshold, linear, and saturation ranges in most human volunteers during one held expiration.

Introversion and individual differences in middle ear acoustic reflex function.

PubMed

Bar-Haim, Yair

2002-10-01

A growing body of psychophysiological evidence points to the possibility that individual differences in early auditory processing may contribute to social withdrawal and introverted tendencies. The present study assessed the response characteristics of the acoustic reflex arc of introverted-withdrawn and extraverted-sociable individuals. Introverts displayed a greater incidence of abnormal middle ear acoustic reflexes and lower acoustic reflex amplitudes than extraverts. These findings were strongest for stimuli presented at a frequency of 2000 Hz. Results are discussed in light of the controversy concerning the anatomic loci (peripheral vs. central neuronal activity) of the individual differences between introverts and extraverts in early auditory processing. Copyright 2002 Elsevier Science B.V.

Cretaceous to Recent Asymetrical Subsidence of South American and West African Conjugate Margins

NASA Astrophysics Data System (ADS)

Kenning, J.; Mann, P.

2017-12-01

Two divergent interpretations have been proposed for South American rifted-passive margins: the "mirror hypothesis" proposes that the rifted margins form symmetrically from pure shear of the lithosphere while upper-plate-lower plate models propose that the rifted margins form asymmetrically by simple shear. Models based on seismic reflection and refraction imaging and comparison of conjugate, rifted margins generally invoke a hybrid stretching process involving elements of both end member processes along with the effects of mantle plumes active during the rift and passive margin phases. We use subsidence histories of 14, 1-7 km-deep exploration wells located on South American and West African conjugate pairs now separated by the South Atlantic Ocean, applying long-term subsidence to reveal the symmetry or asymmetry of the underlying, conjugate, rift processes. Conjugate pairs characterize the rifted margin over a distance of 3500 km and include: Colorado-South Orange, Punta Del Este-North Orange, South Pelotas-Lüderitz and the North Pelotas-Walvis Basins. Of the four conjugate pairs, more rapid subsidence on the South American plate is consistently observed with greater initial rift and syn-rift subsidence rates of >60m/Ma (compared to <15 m/Ma) between approximately 145-115 Ma. High rates of tectonically-induced subsidence >100 m/Ma are observed offshore South Africa between approximately 120-80 Ma, compatible with onset of the post-rift thermal sag phase. During this period the majority of burial is completed and rates remain low at <10 m/Ma during most of the late Cretaceous and Cenozoic. The conjugate margin of Argentina/Uruguay displays more gradual subsidence throughout the Cretaceous, consistently averaging a moderate 15-30m/Ma. By the end of this stage there is a subsequent increase to 25-60 m/Ma within the last 20 Ma, interpreted to reflect lithospheric loading due to increased sedimentation rates during the Cenozoic. This increase in subsidence rate is not seen in the African conjugate section where the majority of sediments bypassed the highly aggraded Cretaceous shelf. Initially greater on the Brazilian margin compared to Namibia, here both margins exhibit moderate-steep subsidence curves until 65-55 Ma where there is reduced subsidence during much of the Late Cretaceous until 20 Ma.

[Spatial variation of soil carbon and stable isotopes in the southern margin desert of Junggar Basin, China].

PubMed

Wang, Na; Xu, Wen Qiang; Xu, Hua Jun; Feng, Yi Xing; Li, Chao Fan

2017-07-18

The southern margin desert of Junggar Basin in the central arid region of Asia was selec-ted as the study area. To gain insight into the distribution characteristic of stable carbon isotope and the relationship between the change of soil carbon and the distance to oasis of soil organic carbon (SOC) and soil inorganic carbon (SIC), three belt transects were set according to the distance between the desert and the oasis in edge, middle and hinterland of the desert respectively, and collected the soil profile samples with depth of 2 m. The results indicated that the SOC content reduced with the soil depth, and the variation with the distance to oasis was the edge> the middle> the hinterland. The δ 13 C value of SOC varied in the range of -21.92‰ to -17.41‰, and decreased with the depth; the range in the middle and hinterland was -25.20‰ to -19.30‰, and increased then declined with the depth. Therefore, we could infer that the C3 plants played a dominant role in the central of desert, and had experienced the succession from C3 plants to C4 plants. The average content of SIC was 38.98 g·kg -1 in the edge of desert, which was about 6.01 folds as large as the content in the hinterland. This indicated that a large number of SIC with 0-2 m depth were clustered in the edge of the desert. The δ 13 C value of SIC increased first then decreased with the soil depth, and enriched in the bottom layer, which was mainly affected by the original carbonate content and soil carbon dioxide.

[Effects of highway on the vegetation species composition along a distance gradient from road edge in southeastern margin of Tengeer Desert].

PubMed

Feng, Li; Li, Xin-Rong; Guo, Qun; Zhang, Jing-Guang; Zhang, Zhi-Shan

2011-05-01

Aimed to examine the effects of highway on the vegetation species composition in arid desert area, forty-eight transects perpendicular to the provincial highway 201 from Shapotou to Jing-tai in the southeastern margin of Tengger Desert were installed, with the vegetation species distribution along a distance gradient from the road edge investigated. The results showed that with increasing distance from the road edge, the species number, coverage, biomass, and alpha-diversity of herbaceous plants declined, but had no significant differences with the control beyond 5 m. Within 0-6 m to the road edge, the herbaceous plant height was greater than that of the control, but their density had less change. Within 0-2 m to the road edge, the species turnover rate of herbaceous plants was lower; at 2-5m, this rate was the highest; while beyond 10 m, the species composition of herbaceous plants was similar to that of the control. The herbaceous plant community at the road edge was dominated by gramineous plants, with the disturbance-tolerant species Pennisetum centrasiaticum, Chloris virgata, and Agropyron cristatum accounting for 68.6% of the total. C. virgata beyond 1 m to the road edge had a rapid decrease in its individual number and presence frequency, P. centrasiaticum and A. cristatum beyond 2 m also showed a similar trend, while the composite plants Artemisia capillaris and A. frigida beyond 2 m from the road edge had a rapid increase in its individual number, accounting for 70% of the herbaceous plants. At the road edge, the coverage and density of shrubs were significantly lower than those of the control, but the species composition had no significant difference.

Assessment of stability during gait in patients with spinal deformity-A preliminary analysis using the dynamic stability margin.

PubMed

Simon, Anne-Laure; Lugade, Vipul; Bernhardt, Kathie; Larson, A Noelle; Kaufman, Kenton

2017-06-01

Daily living activities are dynamic, requiring spinal motion through space. Current assessment of spinal deformities is based on static measurements from full-spine standing radiographs. Tools to assess dynamic stability during gait might be useful to enhance the standard evaluation. The aim of this study was to evaluate gait dynamic imbalance in patients with spinal deformity using the dynamic stability margin (DSM). Twelve normal subjects and 17 patients with spinal deformity were prospectively recruited. A kinematic 3D gait analysis was performed for the control group (CG) and the spinal deformity group (SDG). The DSM (distance between the extrapolated center of mass and the base of support) and time-distance parameters were calculated for the right and left side during gait. The relationship between DSM and step length was assessed using three variables: gait stability, symmetry, and consistency. Variables' accuracy was validated by a discriminant analysis. Patients with spinal deformity exhibited gait instability according to the DSM (0.25m versus 0.31m) with decreased velocity (1.1ms -1 versus 1.3ms -1 ) and decreased step length (0.32m versus 0.38m). According to the discriminant analysis, gait stability was the more accurate variable (area under the curve AUC=0.98) followed by gait symmetry and consistency. However, gait consistency showed 100% of specificity, sensitivity, and accuracy of precision. The DSM showed that patients with spinal malalignment exhibit decreased gait stability, symmetry, and consistency besides gait time-distance parameter changes. Additional work is required to determine how to apply the DSM for preoperative and postoperative spinal deformity management. Copyright © 2017. Published by Elsevier B.V.

Binary Multidimensional Scaling for Hashing.

PubMed

Huang, Yameng; Lin, Zhouchen

2017-10-04

Hashing is a useful technique for fast nearest neighbor search due to its low storage cost and fast query speed. Unsupervised hashing aims at learning binary hash codes for the original features so that the pairwise distances can be best preserved. While several works have targeted on this task, the results are not satisfactory mainly due to the oversimplified model. In this paper, we propose a unified and concise unsupervised hashing framework, called Binary Multidimensional Scaling (BMDS), which is able to learn the hash code for distance preservation in both batch and online mode. In the batch mode, unlike most existing hashing methods, we do not need to simplify the model by predefining the form of hash map. Instead, we learn the binary codes directly based on the pairwise distances among the normalized original features by Alternating Minimization. This enables a stronger expressive power of the hash map. In the online mode, we consider the holistic distance relationship between current query example and those we have already learned, rather than only focusing on current data chunk. It is useful when the data come in a streaming fashion. Empirical results show that while being efficient for training, our algorithm outperforms state-of-the-art methods by a large margin in terms of distance preservation, which is practical for real-world applications.

Hierarchical Probabilistic Inference of the Color-Magnitude Diagram and Shrinkage of Stellar Distance Uncertainties

NASA Astrophysics Data System (ADS)

Leistedt, Boris; Hogg, David W.

2017-12-01

We present a hierarchical probabilistic model for improving geometric stellar distance estimates using color-magnitude information. This is achieved with a data-driven model of the color-magnitude diagram, not relying on stellar models but instead on the relative abundances of stars in color-magnitude cells, which are inferred from very noisy magnitudes and parallaxes. While the resulting noise-deconvolved color-magnitude diagram can be useful for a range of applications, we focus on deriving improved stellar distance estimates relying on both parallax and photometric information. We demonstrate the efficiency of this approach on the 1.4 million stars of the Gaia TGAS sample that also have AAVSO Photometric All Sky Survey magnitudes. Our hierarchical model has 4 million parameters in total, most of which are marginalized out numerically or analytically. We find that distance estimates are significantly improved for the noisiest parallaxes and densest regions of the color-magnitude diagram. In particular, the average distance signal-to-noise ratio (S/N) and uncertainty improve by 19% and 36%, respectively, with 8% of the objects improving in S/N by a factor greater than 2. This computationally efficient approach fully accounts for both parallax and photometric noise and is a first step toward a full hierarchical probabilistic model of the Gaia data.

The frequency of buccopalpebral reflex in Parkinson disease.

PubMed

Eser, Hülya; Ünal, Yasemin; Kutlu, Gülnihal; Öcal, Ruhsen; İnan, Levent Ertuğrul

2016-11-17

This study aimed to define the frequency of a primitive reflex, the buccopalpebral reflex (BPR), and its association with the clinical situation in patients with Parkinson disease. Between May 2010 and May 2011, 222 patients, 115 with Parkinson disease and 107 patients without any sign of neurodegenerative disease, were included in the study. All included patients were examined for BPR and snout reflex and were also evaluated with the Mini Mental State Examination. All patients with Parkinson disease were classified with the Unified Parkinson's Disease Rating Scale (UPDRS) and the Hoehn and Yahr Score to determine their clinical severity. Sixteen patients with Parkinson disease (13.9%) had a BPR (+) and 4 patients in the control group (3.7%) (P < 0.001). The UPDRS score, UPDRS daily life activities score, and UPDRS motor system score were all higher in the group with BPR (+). All patients with a BPR also had a positive snout reflex. BPR is more frequent in patients with Parkinson disease than in patients without a neurodegenerative disease.

Intramuscular Neurotrophin-3 normalizes low threshold spinal reflexes, reduces spasms and improves mobility after bilateral corticospinal tract injury in rats.

PubMed

Kathe, Claudia; Hutson, Thomas Haynes; McMahon, Stephen Brendan; Moon, Lawrence David Falcon

2016-10-19

Brain and spinal injury reduce mobility and often impair sensorimotor processing in the spinal cord leading to spasticity. Here, we establish that complete transection of corticospinal pathways in the pyramids impairs locomotion and leads to increased spasms and excessive mono- and polysynaptic low threshold spinal reflexes in rats. Treatment of affected forelimb muscles with an adeno-associated viral vector (AAV) encoding human Neurotrophin-3 at a clinically-feasible time-point after injury reduced spasticity. Neurotrophin-3 normalized the short latency Hoffmann reflex to a treated hand muscle as well as low threshold polysynaptic spinal reflexes involving afferents from other treated muscles. Neurotrophin-3 also enhanced locomotor recovery. Furthermore, the balance of inhibitory and excitatory boutons in the spinal cord and the level of an ion co-transporter in motor neuron membranes required for normal reflexes were normalized. Our findings pave the way for Neurotrophin-3 as a therapy that treats the underlying causes of spasticity and not only its symptoms.

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

PubMed

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.