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Sample records for sensorineuralem hoerverlust vor

  1. Keine Panik vor Statistik!

    NASA Astrophysics Data System (ADS)

    Oestreich, Markus; Romberg, Oliver

    Die Statistik - unendliche Fragen. Sternzeit 0511,22: Wir schreiben das Jahr mit J wie "Juhu!" denn dies sind die Abenteuer der Doktorissimi Oestreich und Romberg, die mit Ihrem zusammen 28 Punkte zählenden IQ zwei Jahre lang unterwegs waren, um neue Statistik-Darstellungen zu erforschen, neue Formulierungen und neue Applikationen. Viele Lichtjahre von der faden Theorie entfernt, dringen die Autoren dabei in Phantasien vor, die nie ein Mensch zuvor so gehabt hat. Willkommen an Bord!

  2. A digital goniometer for VOR

    NASA Technical Reports Server (NTRS)

    Meer, S. A.

    1977-01-01

    A new VOR (VHF omni-range) goniometer design which promises to improve the reliability and maintainability of the VOR ground station is described. The heart of the new concept is the use of two digital phase shifters to produce the rotating figure-of-eight pattern of conventional VOR. Using digital circuits, the goniometer adjustments and calibration reduce to timing adjustments of binary signals. A common clock used for timing the digital phase shifters also synchronizes the 30 Hz modulation of the 9.96 kHz reference.

  3. VOR area navigation - Techniques and results

    NASA Technical Reports Server (NTRS)

    Ragsdale, W. A.

    1982-01-01

    Several methods for deriving position from VOR (without DME) have been developed and evaluated in this study. These methods permit navigation to arbitrary waypoints using either two VOR's or one VOR and a clock. These algorithms have been tested in computer simulations and in flight tests. The single VOR method appears to be the most practical and is a candidate for an automated light plane area navigation system, called VORNAV.

  4. 14 CFR 91.171 - VOR equipment check for IFR operations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false VOR equipment check for IFR operations. 91... Instrument Flight Rules § 91.171 VOR equipment check for IFR operations. (a) No person may operate a civil aircraft under IFR using the VOR system of radio navigation unless the VOR equipment of that aircraft—...

  5. 77 FR 64444 - VOR Federal Airway V-595; Oregon

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-22

    ... ``significant rule'' under Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034... read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 VOR Federal Airway V-595; Oregon...

  6. Liposomal voriconazole (VOR) formulation for improved ocular delivery.

    PubMed

    de Sá, Fernando Augusto Pires; Taveira, Stephânia Fleury; Gelfuso, Guilherme Martins; Lima, Eliana Martins; Gratieri, Taís

    2015-09-01

    Treating infectious eye diseases topically requires a drug delivery system capable of overcoming the eye's defense mechanisms, which efficiently reduce the drug residence time right after its administration, therefore reducing absorption. In order to try to surpass such administration issues and improve life quality for patients with fungal keratitis, liposomal voriconazol (VOR) formulations were prepared. Formulations were composed of soy phosphatidylcholine (PC) containing or not 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and cholesterol. Liposomes were characterized by their drug entrapment efficiency (EE), drug recovery (DR), average diameter (size) and polydispersivity index (PdI). In vitro mucosal interaction and irritancy levels, ex vivo permeation, as well as the short-term stability were also assessed. Liposomal VOR formulation produced with 7.2:40mM VOR:PC showed to be the most promising formulation: mean size of 116.6±5.9nm, narrow PdI (0.17±0.06), negative zeta potential (∼-7mV) and over 80% of EE and yield, remaining stable for at least 30 days in solution and 90 days after lyophilization. This formulation was classified as 'non-irritant' after HET-CAM's test and was able to deliver about 47.85±5.72μg/cm(2) of VOR into porcine cornea after 30min of permeation test. Such drug levels are higher than the minimal inhibitory concentrations (MIC) of several fungi species isolated from clinical cases of corneal keratitis. Overall results suggest VOR can be effectively incorporated in liposomes for potential topical treatment of fungal keratitis. PMID:26123854

  7. 14 CFR 71.15 - Designation of jet routes and VOR Federal airways.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Designation of jet routes and VOR Federal... ROUTES; AND REPORTING POINTS § 71.15 Designation of jet routes and VOR Federal airways. Unless otherwise... subpart A of FAA Order 7400.9T, and as VOR Federal airways in subpart E of FAA Order 7400.9T, are...

  8. Updating inertial navigation systems with VOR/DME information.

    NASA Technical Reports Server (NTRS)

    Bobick, J. C.; Bryson, A. E., Jr.

    1972-01-01

    Demonstration that updating an inertial navigation system (INS) with VOR/DME information (from one or two stations) by means of a maximum-likelihood filter results in substantial improvements in navigational accuracy over that obtained by the use of a single VOR/DME (current practice). When continuously updating, the use of a high-quality INS (0.01 deg/hr gyro drift) instead of a low-quality INS (1.0 deg/hr gyro drift) does not substantially improve position accuracy. In-flight alignment (or realignment) of an INS to an accuracy comparable to that of ground alignment can be accomplished by using two DMEs. Several reduced-order suboptimal filters were found to perform nearly optimally.

  9. Multiple timescales in the adaptation of the rotational VOR

    PubMed Central

    Colagiorgio, Paolo; Bertolini, Giovanni; Bockisch, Christopher J.; Straumann, Dominik

    2015-01-01

    Goal-directed movements, such as pointing and saccades, have been shown to share similar neural architectures, in spite of the different neuromuscular systems producing them. Such structure involve an inverse model of the actuator being controlled, which produces the commands innervating the muscles, and a forward model of the actuator, which predicts the sensory consequences of such commands and allows online movement corrections. Recent studies have shown that goal-directed movements also share similar motor-learning and motor-memory mechanisms, which are based on multiple timescales. The hypothesis that also the rotational vestibulo-ocular reflex (rVOR) may be based on a similar architecture has been presented recently. We hypothesize that multiple timescales are the brain's solution to the plasticity-stability dilemma, allowing adaptation to temporary and sudden changes while keeping stable motor-control abilities. If that were the case, then we would also expect the adaptation of reflex movements to follow the same principles. Thus we studied rVOR gain adaptation in eight healthy human subjects using a custom paradigm aimed at investigating the existence of spontaneous recovery, which we considered as the hallmark of multiple timescales in motor learning. Our experimental results show that spontaneous recovery occurred in six of eight subjects. Thus we developed a mathematical model of rVOR adaptation based on two hidden-states processes, which adapts the cerebellar-forward model of the ocular motor plant, and show that it accurately simulates our experimental data on rVOR gain adaptation, whereas a single timescale learning process fails to do so. PMID:25744882

  10. The Human Vertical Translation Vestibulo-ocular Reflex (tVOR): Normal and Abnormal Responses

    PubMed Central

    Liao, Ke; Walker, Mark F.; Joshi, Anand; Reschke, Millard; Strupp, Michael; Leigh, R. John

    2010-01-01

    Geometric considerations indicate that the human translational vestibulo-ocular reflex (tVOR) should have substantially different properties than the angular vestibulo-ocular reflex (aVOR). Specifically, tVOR cannot simultaneously stabilize images of distant and near objects on the retina. Most studies make the tacit assumption that tVOR acts to stabilize foveal images even though, in humans, tVOR is reported to compensate for less than 60% of foveal image motion. We have determined that the compensation gain (eye rotational velocity / required eye rotational velocity to maintain foveal target fixation) of tVOR is held steady at ~ 0.6 during viewing of either near or distant targets during vertical (bob) translations in ambient illumination. We postulate that tVOR evolved not to stabilize the image of the target on the fovea, but rather to minimize retinal image motion between objects lying in different depth planes, in order to optimize motion parallax information. Such behavior is optimized when binocular visual cues of both far and distant targets are available in ambient light. Patients with progressive supranuclear palsy or cerebellar ataxia show impaired ability to increase tVOR responses appropriately when they view near targets. In cerebellar patients, impaired ability to adjust tVOR responses to viewing conditions occurs despite intact ability to converge at near. Loss of the ability to adjust tVOR according to viewing conditions appears to represent a distinct disorder of vestibular function. PMID:19645882

  11. Listing's Plane and the 3D-VOR in Microgravity

    NASA Astrophysics Data System (ADS)

    Clarke, Andrew H.

    2008-06-01

    Listing's Plane (LP) and the 3D vestibulo-ocular response (3D-VOR) have been shown to be collinear under normal 1G conditions. Here LP and 3D-VOR were recorded under 1G and 0G conditions to determine whether this collinearity is dependent on the gravity vector. Ten healthy subjects participated in a parabolic flight study.. In 0G the orientation of Listing's Plane (LP) was consistently altered. LP elevation was tilted backwards by approx. 10° (p= 0.003). The azimuth angles of the left & right eyes also diverged in zero-G, with a statistically significant change (p = 0.04) in the vergence angle between 6.1 & 11.8°. A dissociation in torsional eye position between 1G and 0G was also observed, which proved to be statistically significant (p = 0.03). The results of spaceflight measurements onboard the ISS demonstrate that this LP re-orientation persists over six-month 0G periods. Furthermore postflight re-adaptation to 1G Earthbound conditions proceeds over several days to weeks. The findings support the idea that the absence of the gravity vector represents a qualitative change not only for vestibular and oculomotor responses, but also for the entire sensorimotor complex and the autonomic system.

  12. VOR Gain Is Related to Compensatory Saccades in Healthy Older Adults

    PubMed Central

    Anson, Eric R.; Bigelow, Robin T.; Carey, John P.; Xue, Qian-Li; Studenski, Stephanie; Schubert, Michael C.; Agrawal, Yuri

    2016-01-01

    Objective: Vestibulo-ocular reflex (VOR) gain is well-suited for identifying rotational vestibular dysfunction, but may miss partial progressive decline in age-related vestibular function. Since compensatory saccades might provide an alternative method for identifying subtle vestibular decline, we describe the relationship between VOR gain and compensatory saccades in healthy older adults. Methods: Horizontal VOR gain was measured in 243 subjects age 60 and older from the Baltimore Longitudinal Study of Aging using video head impulse testing (HIT). Saccades in each HIT were identified as either “compensatory” or “compensatory back-up,” i.e., same or opposite direction as the VOR response respectively. Saccades were also classified as “covert” (occurring during head movement) and “overt” (occurring after head movement). The relationship between VOR gain and percentage of HITs with saccades, as well as the relationship between VOR gain and saccade latency and amplitude, were evaluated using regression analyses adjusting for age, gender, and race. Results: In adjusted analyses, the percentage of HITs with compensatory saccades increased 4.5% for every 0.1 decrease in VOR gain (p < 0.0001). Overt compensatory saccade amplitude decreased 0.6° (p < 0.005) and latency increased 90 ms (p < 0.001) for every 0.1 increase in VOR gain. Covert back-up compensatory saccade amplitude increased 0.4° for every 0.1 increase in VOR gain. Conclusion: We observed significant relationships between VOR gain and compensatory saccades in healthy older adults. Lower VOR gain was associated with larger amplitude, shorter latency compensatory saccades. Compensatory saccades reflect underlying rotational vestibular hypofunction, and may be particularly useful at identifying partial vestibular deficits as occur in aging adults. PMID:27445793

  13. Effect of Spaceflight on Vestibulo-Ocular Reflexes (VORS) During Angular Head Motion

    NASA Technical Reports Server (NTRS)

    Tomko, David L.; Clifford, James O.; Hargens, Alan R. (Technical Monitor)

    1996-01-01

    Vestibulo-ocular reflexes (VORs) stabilize the eyes during head motion. During Earth-horizontal (E-H) pitch or roll rotations, canal and otolith stimuli occur together. In Earth-vertical (E-V) pitch or roll rotations, only canal signals occur. In cats and squirrel monkeys, pitch/roll VOR gains during E-H motion have been shown to be larger than during E-V motion, implying that otolith modulation plays a role in producing angular VORs (aVORs). The present experiments replicated this experiment in rhesus monkeys, and examined how spaceflight affected AVOR gain. During yaw, pitch and roll (0.5 - 1.0 Hz, 40-50 deg/s pk) motion, 3-d eye movements were recorded in four Rhesus monkeys using scleral search coils. Mean E-H and E-V pitch VOR gains were 0.85 and 0.71. Torsional VOR gains during E-H and E-V were 0.47 and 0.39. Gains are more compensatory during E-H pitch or roll. Two of the four monkeys flew for 11 days on the COSMOS 2229 Biosatellite. E-H pitch VOR gains were attenuated immediately (72 hrs) post-flight, with similar values to pre-flight E-V pitch gains. Horizontal yaw VOR gains were similar pre- and post-flight.

  14. Modeling learning in brain stem and cerebellar sites responsible for VOR plasticity

    NASA Technical Reports Server (NTRS)

    Quinn, K. J.; Didier, A. J.; Baker, J. F.; Peterson, B. W.

    1998-01-01

    A simple model of vestibuloocular reflex (VOR) function was used to analyze several hypotheses currently held concerning the characteristics of VOR plasticity. The network included a direct vestibular pathway and an indirect path via the cerebellum. An optimization analysis of this model suggests that regulation of brain stem sites is critical for the proper modification of VOR gain. A more physiologically plausible learning rule was also applied to this network. Analysis of these simulation results suggests that the preferred error correction signal controlling gain modification of the VOR is the direct output of the accessory optic system (AOS) to the vestibular nuclei vs. a signal relayed through the cerebellum via floccular Purkinje cells. The potential anatomical and physiological basis for this conclusion is discussed, in relation to our current understanding of the latency of the adapted VOR response.

  15. Vestibular Compensation in Unilateral Patients Often Causes Both Gain and Time Constant Asymmetries in the VOR

    PubMed Central

    Ranjbaran, Mina; Katsarkas, Athanasios; Galiana, Henrietta L.

    2016-01-01

    The vestibulo-ocular reflex (VOR) is essential in our daily life to stabilize retinal images during head movements. Balanced vestibular functionality secures optimal reflex performance which otherwise can be distorted by peripheral vestibular lesions. Luckily, vestibular compensation in different neuronal sites restores VOR function to some extent over time. Studying vestibular compensation gives insight into the possible mechanisms for plasticity in the brain. In this work, novel experimental analysis tools are employed to reevaluate the VOR characteristics following unilateral vestibular lesions and compensation. Our results suggest that following vestibular lesions, asymmetric performance of the VOR is not only limited to its gain. Vestibular compensation also causes asymmetric dynamics, i.e., different time constants for the VOR during leftward or rightward passive head rotation. Potential mechanisms for these experimental observations are provided using simulation studies. PMID:27065839

  16. Vestibular Compensation in Unilateral Patients Often Causes Both Gain and Time Constant Asymmetries in the VOR.

    PubMed

    Ranjbaran, Mina; Katsarkas, Athanasios; Galiana, Henrietta L

    2016-01-01

    The vestibulo-ocular reflex (VOR) is essential in our daily life to stabilize retinal images during head movements. Balanced vestibular functionality secures optimal reflex performance which otherwise can be distorted by peripheral vestibular lesions. Luckily, vestibular compensation in different neuronal sites restores VOR function to some extent over time. Studying vestibular compensation gives insight into the possible mechanisms for plasticity in the brain. In this work, novel experimental analysis tools are employed to reevaluate the VOR characteristics following unilateral vestibular lesions and compensation. Our results suggest that following vestibular lesions, asymmetric performance of the VOR is not only limited to its gain. Vestibular compensation also causes asymmetric dynamics, i.e., different time constants for the VOR during leftward or rightward passive head rotation. Potential mechanisms for these experimental observations are provided using simulation studies. PMID:27065839

  17. Modeling learning in brain stem and cerebellar sites responsible for VOR plasticity.

    PubMed

    Quinn, K J; Didier, A J; Baker, J F; Peterson, B W

    1998-07-01

    A simple model of vestibuloocular reflex (VOR) function was used to analyze several hypotheses currently held concerning the characteristics of VOR plasticity. The network included a direct vestibular pathway and an indirect path via the cerebellum. An optimization analysis of this model suggests that regulation of brain stem sites is critical for the proper modification of VOR gain. A more physiologically plausible learning rule was also applied to this network. Analysis of these simulation results suggests that the preferred error correction signal controlling gain modification of the VOR is the direct output of the accessory optic system (AOS) to the vestibular nuclei vs. a signal relayed through the cerebellum via floccular Purkinje cells. The potential anatomical and physiological basis for this conclusion is discussed, in relation to our current understanding of the latency of the adapted VOR response. PMID:9671263

  18. GNL-HybELS: an algorithm to classify and identify VOR responses simultaneously.

    PubMed

    Ghoreyshi, Atiyeh; Galiana, Henrietta L

    2010-01-01

    The Vestibulo-Ocular Reflex (VOR) stabilizes the images of the world on the retinae when the head is in motion. Basic daily activities such as walking or driving depend on the proper functioning of this reflex. For several decades, scientists have developed methods to model and identify this system mathematically. However, traditional methods cannot analyze VOR data comprehensively because they disregard pieces of data (fast phases) which biases estimated reflex dynamics. Here we propose, for the first time, an automated tool to analyze entire VOR responses (slow and fast phases), without apriori classification of nystagmus segments. PMID:21097023

  19. A design study of VOR: A versatile optimal resolution chopper spectrometer for the ESS

    NASA Astrophysics Data System (ADS)

    Deen, P. P.; Vickery, A.; Andersen, K. H.; Hall-Wilton, R.

    2015-01-01

    VOR, the versatile optimal resolution chopper spectrometer, is designed to probe dynamic phenomena that are currently inaccessible for inelastic neutron scattering due to flux limitations. VOR is a short instrument by the standards of the European Spallation Source (ESS), 30.2 m moderator to sample, and provides instantaneous access to a broad dynamic range, 1-120 meV within each ESS period. The short instrument length combined with the long ESS pulse width enables a quadratic flux increase, even at longer wavelengths, by relaxing energy resolution from ΔE/E = 1% up to ΔE/E = 7%. This is impossible both on a long chopper spectrometer at the ESS and with instruments at short pulsed sources. In comparison to current day chopper spectrometers, VOR can offer an order of magnitude improvement in flux for equivalent energy resolutions, ΔE/E = 1-3%. Further relaxing the energy resolution enables VOR to gain an extra order of magnitude in flux. In addition, VOR has been optimised for repetition rate multiplication (RRM) and is therefore able to measure, in a single ESS period, 6-14 incident wavelengths, across a wavelength band of 9 Å with a novel chopper configuration that transmits all incident wavelengths with equivalent counting statistics. The characteristics of VOR make it a unique instrument with capabilities to access small, limited-lifetime samples and transient phenomena with inelastic neutron scattering.

  20. 78 FR 21856 - Proposed Amendment of VOR Federal Airway V-537; GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-12

    ...This SNPRM amends a notice of proposed rulemaking (NPRM) published on October 15, 2012 which proposed to amend VHF omnidirectional range (VOR) Federal airway V-537 in Georgia. This SNPRM proposes to remove an additional segment of the airway due to navigation aid coverage...

  1. 14 CFR 91.171 - VOR equipment check for IFR operations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... more than 20 nautical miles from the VOR ground facility and maneuver the aircraft directly over the... sign the aircraft log or other record. In addition, if a test signal radiated by a repair station, as...) Use, at the airport of intended departure, an FAA-operated or approved test signal or a test...

  2. 14 CFR 91.171 - VOR equipment check for IFR operations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... more than 20 nautical miles from the VOR ground facility and maneuver the aircraft directly over the... sign the aircraft log or other record. In addition, if a test signal radiated by a repair station, as...) Use, at the airport of intended departure, an FAA-operated or approved test signal or a test...

  3. 14 CFR 91.171 - VOR equipment check for IFR operations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... more than 20 nautical miles from the VOR ground facility and maneuver the aircraft directly over the... sign the aircraft log or other record. In addition, if a test signal radiated by a repair station, as...) Use, at the airport of intended departure, an FAA-operated or approved test signal or a test...

  4. 14 CFR 91.171 - VOR equipment check for IFR operations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... more than 20 nautical miles from the VOR ground facility and maneuver the aircraft directly over the... sign the aircraft log or other record. In addition, if a test signal radiated by a repair station, as...) Use, at the airport of intended departure, an FAA-operated or approved test signal or a test...

  5. 77 FR 54859 - Proposed Establishment of VOR Federal Airway V-629; Las Vegas, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory..., 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 2. The incorporation by... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Proposed Establishment of VOR Federal...

  6. 77 FR 42428 - Amendment of Jet Routes and VOR Federal Airways; Northeastern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-19

    ... Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR... follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp... 2120-AA66 Amendment of Jet Routes and VOR Federal Airways; Northeastern United States AGENCY:...

  7. 77 FR 26160 - Modification of VOR Federal Airway V-14; Missouri

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-03

    ... the Federal Register of May 7, 1990 (55 FR 18862), the St. Louis, MO, VOR/DME was deleted from the... Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and..., 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation...

  8. 78 FR 72005 - Amendment of VOR Federal Airway V-374, Northeastern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-02

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR 71.1...-AEA-17 RIN 2120-AA66 Amendment of VOR Federal Airway V-374, Northeastern United States AGENCY:...

  9. 78 FR 9009 - Proposed Amendment of VOR Federal Airway V-595; OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-07

    ... Federal airway V-595 due to the planned decommissioning of the Portland, OR, VOR/DME (77 FR 64444). No... ``significant rule'' under Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034... read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR,...

  10. 76 FR 12645 - Proposed Revocation of VOR Federal Airway V-284; New Jersey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-08

    ... amend Title 14, Code of Federal Regulations (14 CFR) part 71 by removing VOR Federal Airway V-284 (75 FR... NPRM published in the Federal Register on September 3, 2010 (75 FR 54058) . Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854; 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Issued in Washington,...

  11. 76 FR 2800 - Amendment of VOR Federal Airways V-2 and V-21; Hawaii

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation... TRANSPORTATION Federal Aviation Administration 14 CFR Part 71 Amendment of VOR Federal Airways V-2 and...

  12. 77 FR 62468 - Proposed Amendment of VOR Federal Airway V-537, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-15

    ... ``significant rule'' under Department of Transportation (DOT) Regulatory ] Policies and Procedures (44 FR 11034... continues to read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3... 2120-AA66 Proposed Amendment of VOR Federal Airway V-537, GA AGENCY: Federal Aviation...

  13. 75 FR 54058 - Proposed Revocation of VOR Federal Airway V-284; New Jersey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-03

    ... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory...: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Proposed Revocation of VOR Federal Airway...

  14. 78 FR 72005 - Amendment of VOR Federal Airway V-45, North Carolina

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-02

    ... Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a Regulatory Evaluation... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR 71.1... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of VOR Federal Airway V-45,...

  15. 76 FR 82114 - Amendment of VOR Federal Airways V-320 and V-440; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-30

    ... Anchorage VOR navigation aid (76 FR 68674). Interested parties were invited to participate in this... (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory evaluation as.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in...

  16. 78 FR 24346 - Modification of VOR Federal Airway V-595, Oregon

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ... area (78 FR 4354, January 22, 2013. VOR Federal airways are published in paragraph 6010(a) of FAA Order... (77 FR 64444). Interested parties were invited to participate in this rulemaking effort by submitting... FAA issued a supplemental NPRM (SNPRM) (78 FR 9009, February 7, 2013) to solicit comments on...

  17. Development of a VOR/DME model for an advanced concepts simulator

    NASA Technical Reports Server (NTRS)

    Steinmetz, G. G.; Bowles, R. L.

    1984-01-01

    The report presents a definition of a VOR/DME, airborne and ground systems simulation model. This description was drafted in response to a need in the creation of an advanced concepts simulation in which flight station design for the 1980 era can be postulated and examined. The simulation model described herein provides a reasonable representation of VOR/DME station in the continental United States including area coverage by type and noise errors. The detail in which the model has been cast provides the interested researcher with a moderate fidelity level simulator tool for conducting research and evaluation of navigator algorithms. Assumptions made within the development are listed and place certain responsibilities (data bases, communication with other simulation modules, uniform round earth, etc.) upon the researcher.

  18. Impaired vestibulo-ocular reflex (VOR) in spinocerebellar ataxia type 3 (SCA3): bedside and search coil evaluation.

    PubMed

    Gordon, Carlos R; Zivotofsky, Ari Z; Caspi, Avi

    2014-01-01

    Vestibulo-Ocular Reflex (VOR) abnormalities in cerebellar ataxias are a matter of renewed interest. We have previously reported vestibular areflexia in a group of Yemenite-Jews with Spinocerebellar Ataxia Type 3 (SCA3) who had clear bilateral pathological horizontal Head Impulse Test (HIT). The objective of this study was to evaluate the VOR of ten SCA3 patients who have variable bedside HIT responses by recording their eye movements using magnetic search coils and to correlate these results with their clinical and genetic data. Eight out of the ten patients have abnormal horizontal HIT detected by both clinical bedside examination and laboratory tests. Results of bedside HIT testing were significantly correlated with the VOR gain recorded using magnetic search coils. No significant correlations were found between VOR gain and other clinical or genetic data. Our study confirms the presence of defective VOR in SCA3 patients and corroborates the useful of the HIT as a reliable bedside test for diagnosis of VOR deficits. PMID:25564077

  19. A rodent model for artificial gravity: VOR adaptation and Fos expression.

    PubMed

    Kaufman, Galen; Weng, Tianxiang; Ruttley, Tara

    2005-01-01

    Vestibulo-ocular reflex (VOR) adaptation and brainstem Fos expression as a result of short radius cross-coupling stimuli were investigated to find neural correlates of the inherent Coriolis force asymmetry from an artificial gravity (AG) environment. Head-fixed gerbils (Meriones unguiculatus, N=79) were exposed, in the dark, to 60--90 minutes of cross-coupled rotations, combinations of pitch (or roll) and yaw rotation, while binocular horizontal, vertical, and torsional eye position were determined using infrared video-oculography. Centripetal acceleration in combination with angular cross-coupling was also studied. Simultaneous sinusoidal rotations in two planes (yaw with roll or pitch) provided a net symmetrical stimulus for the right and left labyrinths. In contrast, a constant velocity yaw rotation during sinusoidal roll or pitch provided the asymmetric stimulus model for AG. We found orthogonally oriented half-cycle VOR gain changes. The results depended on the direction of horizontal rotation during asymmetrical cross-coupling, and other aspects of the stimulus, including the phase relationship between the two rotational inputs, the symmetry of the stimulus, and training. Fos expression also revealed laterality differences in the prepositus and inferior olivary C subnucleus. In contrast the inferior olivary beta and ventrolateral outgrowth were labeled bilaterally. Additional cross-coupling dependent labeling was found in the flocculus, hippocampus, and several cortical regions, including the perirhinal and temporal association cortices. Analyses showed significant differences across the brain regions for several factors (symmetry, rotation velocity and direction, the presence of centripetal acceleration or a visual surround, and training). Finally, animals compensating from a unilateral surgical labyrinthectomy who received multiple cross-coupling training sessions had improved half-cycle VOR gain in the ipsilateral eye with head rotation toward the intact

  20. Horizontal angular VOR, nystagmus dumping, and sensation duration in spacelab SLS-1 crewmembers

    NASA Technical Reports Server (NTRS)

    Oman, C. M.; Balkwill, M. D.; Young, L. R. (Principal Investigator)

    1993-01-01

    In 1G, the apparent time constant (Td) of postrotatory SPV decay with the head tilted face down is 55% of that with head erect (Te). This phenomenon is called "nystagmus dumping" and has been attributed to G effects on VOR velocity storage. Similarly, postrotatory sensation duration with head tilted (Dd) is 32% of that when head erect (De). In parabolic flight, Te and De are 70% of 1-G values, but a pitch back dumping movement produces no further change. Te, Td, and Dd have not previously been measured in orbital flight. VOR and sensation duration was tested in 4 crewmembers in 4 preflight, 1 inflight (days 4 or 5) and 4 post flight sessions. Bitemporal EOG was recorded with eyes open in darkness. Instructions were to "gaze straight ahead," and indicate when "rotation sensation disappears or becomes ambiguous". Subjects were rotated CW and CCW head erect for 1 min at 120 degrees/s, stopped, and EOG was recorded for another 1 min. This procedure was then used to study dumping, except that immediately after chair stop, subjects pitched their head forward 90 degrees. SPV was calculated using order statistic filtering, and dropouts removed using an iterative model fitting method. Te and Td were determined by logarithmic linear regression of mean SPV for each subject. In orbit, 90 degrees pitch movement produced rapid subjective dumping, but not nystagmus dumping. Dd was noticeably shorter ("almost instantaneous") compared to preflight Dd. Te and Td in orbit were similar to preflight Te for 3/4 subjects (rather than to preflight Td as expected). No consistent VOR gain changes were seen in orbit. Although Te is known to decrease acutely in parabolic flight, a longer time constant was measured in 3/4 subjects after 4-5 days adaptation to weightlessness, suggesting a return of angular velocity storage.

  1. Short-term adaptation of the VOR: non-retinal-slip error signals and saccade substitution

    NASA Technical Reports Server (NTRS)

    Eggers, Sscott D Z.; De Pennington, Nick; Walker, Mark F.; Shelhamer, Mark; Zee, David S.

    2003-01-01

    We studied short-term (30 min) adaptation of the vestibulo-ocular reflex (VOR) in five normal humans using a "position error" stimulus without retinal image motion. Both before and after adaptation a velocity gain (peak slow-phase eye velocity/peak head velocity) and a position gain (total eye movement during chair rotation/amplitude of chair motion) were measured in darkness using search coils. The vestibular stimulus was a brief ( approximately 700 ms), 15 degrees chair rotation in darkness (peak velocity 43 degrees /s). To elicit adaptation, a straight-ahead fixation target disappeared during chair movement and when the chair stopped the target reappeared at a new location in front of the subject for gain-decrease (x0) adaptation, or 10 degrees opposite to chair motion for gain-increase (x1.67) adaptation. This position-error stimulus was effective at inducing VOR adaptation, though for gain-increase adaptation the primary strategy was to substitute augmenting saccades during rotation while for gain-decrease adaptation both corrective saccades and a decrease in slow-phase velocity occurred. Finally, the presence of the position-error signal alone, at the end of head rotation, without any attempt to fix upon it, was not sufficient to induce adaptation. Adaptation did occur, however, if the subject did make a saccade to the target after head rotation, or even if the subject paid attention to the new location of the target without actually looking at it.

  2. An Indirect System Identification Technique for Stable Estimation of Continuous-Time Parameters of the Vestibulo-Ocular Reflex (VOR)

    NASA Technical Reports Server (NTRS)

    Kukreja, Sunil L.; Wallin, Ragnar; Boyle, Richard D.

    2013-01-01

    The vestibulo-ocular reflex (VOR) is a well-known dual mode bifurcating system that consists of slow and fast modes associated with nystagmus and saccade, respectively. Estimation of continuous-time parameters of nystagmus and saccade models are known to be sensitive to estimation methodology, noise and sampling rate. The stable and accurate estimation of these parameters are critical for accurate disease modelling, clinical diagnosis, robotic control strategies, mission planning for space exploration and pilot safety, etc. This paper presents a novel indirect system identification method for the estimation of continuous-time parameters of VOR employing standardised least-squares with dual sampling rates in a sparse structure. This approach permits the stable and simultaneous estimation of both nystagmus and saccade data. The efficacy of this approach is demonstrated via simulation of a continuous-time model of VOR with typical parameters found in clinical studies and in the presence of output additive noise.

  3. 76 FR 79140 - Proposed Modification of VOR Federal Airways V-135 and V-137; Southwest United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-21

    ...'' under Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26... read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Proposed Modification of VOR Federal...

  4. Graphical Analysis of Electromagnetic Coupling on B-737 and B-757 Aircraft for VOR and LOC IPL Data

    NASA Technical Reports Server (NTRS)

    Jafri, Madiha; Ely, Jay; Vahala, Linda

    2005-01-01

    Electromagnetic coupling measurements were performed from numerous passenger cabin locations to aircraft instrument landing system localizer (LOC) and VHF Omni-Ranging (VOR) systems. This paper presents and compares the data for B-757 and B-737 airplanes, and provides a basis for fuzzy modeling of coupling patterns in different types of airplanes and airplanes with different antenna locations.

  5. 78 FR 18271 - Proposed Modification of VOR Federal Airway V-345 in the Vicinity of Ashland, WI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Proposed Modification of VOR Federal Airway...

  6. 77 FR 54860 - Proposed Modification of VOR Federal Airway V-170 in the Vicinity of Devils Lake, ND

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ...'' under Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26.... 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 2. The... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Proposed Modification of VOR Federal Airway...

  7. 78 FR 37103 - Amendment of VOR Federal Airways V-55 and V-169 in Eastern North Dakota

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-20

    ..., the FAA took action to amend VOR Federal airways V-55 (44 FR 43714, July 26, 1979) and V-169 (44 FR... Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The...

  8. Full-Body Gaze Control Mechanisms Elicited During Locomotion: Effects Of VOR Adaptation

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Houser, J.; Peters, B.; Miller, C.; Richards, J.; Marshburn, A.; Brady, R.; Cohen, H.; Bloomberg, J. J.

    2004-01-01

    Control of locomotion requires precise interaction between several sensorimotor subsystems. During locomotion the performer must satisfy two performance criteria: maintain stable forward translation and to stabilize gaze (McDonald, et al., 1997). Precise coordination demands integration of multiple sensorimotor subsystems for fulfilling both criteria. In order to test the general hypothesis that the whole body can serve as an integrated gaze stabilization system, we have previously investigated how the multiple, interdependent full-body sensorimotor subsystems respond to changes in gaze stabilization task constraints during locomotion (Mulavara and Bloomberg, 2003). The results suggest that the full body contributes to gaze stabilization during locomotion, and that its different functional elements respond to changes in visual task constraints. The goal of this study was to determine how the multiple, interdependent, full-body sensorimotor subsystems aiding gaze stabilization during locomotion are functionally coordinated after the vestibulo-ocular reflex (VOR) gain has been altered. We investigated the potential of adaptive remodeling of the full-body gaze control system following exposure to visual-vestibular conflict known to adaptively reduce the VOR. Subjects (n=14) walked (6.4 km/h) on the treadmill before and after they were exposed to 0.5X manifying lenses worn for 30 minutes during self-generated sinusoidal vertical head rotations performed while seated. In this study we measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, shank and foot, accelerations along the vertical axis at the head and the shank, and the vertical forces acting on the support surface. Results indicate that, following exposure to the 0.5X minifying lenses, there was a significant increase in the duration of stance and stride times, alteration in the amplitude of head movement with respect to space and a significant increase in

  9. [Frequency-specific analysis of the hVOR Prior of Cochlear Implant Operation].

    PubMed

    Hülse, R; Hülse, M; Wenzel, A; Hörmann, K; Servais, J J

    2015-03-01

    Dizziness is one of the most common postoperative complications after a cochlear-implant (CI) surgery. With our prospective, matched-paired controlled study, we could demonstrate that patients with distinctive sensorineural hearing loss--even without any complaints of dizziness--already have a reduced horizontal vestibular-ocular-reflex (hVOR). Compared to controls, CI patients presented with a significantly reduced gain. 9 out of 17 CI patients showed physiological results in rotatory testing and video head thrust testing. One patient presented with pathological results in both tests. Remarkably, there were 2 patients who presented with pathological head impulse testing but normal values in rotatory testing and 5 patients who showed normal gains in video head impulse testing but abnormal rotatory tests. These findings clearly show the importance of a differentiated, frequency-dependent pre-operative vestibular assessment including rotatory testing and video-head impulse testing. Additionally, only an accurate pre-operative vestibular testing allows evaluating possible post-operative dizziness related complications and should be documented precisely, also for forensic reasons. This is the key to differentiate post-operative dizziness from an pre-operatively existing vestibular disorder that possibly might not be clinically apparent by the time of testing. PMID:25265227

  10. A least-squares parameter estimation algorithm for switched hammerstein systems with applications to the VOR

    NASA Technical Reports Server (NTRS)

    Kukreja, Sunil L.; Kearney, Robert E.; Galiana, Henrietta L.

    2005-01-01

    A "Multimode" or "switched" system is one that switches between various modes of operation. When a switch occurs from one mode to another, a discontinuity may result followed by a smooth evolution under the new regime. Characterizing the switching behavior of these systems is not well understood and, therefore, identification of multimode systems typically requires a preprocessing step to classify the observed data according to a mode of operation. A further consequence of the switched nature of these systems is that data available for parameter estimation of any subsystem may be inadequate. As such, identification and parameter estimation of multimode systems remains an unresolved problem. In this paper, we 1) show that the NARMAX model structure can be used to describe the impulsive-smooth behavior of switched systems, 2) propose a modified extended least squares (MELS) algorithm to estimate the coefficients of such models, and 3) demonstrate its applicability to simulated and real data from the Vestibulo-Ocular Reflex (VOR). The approach will also allow the identification of other nonlinear bio-systems, suspected of containing "hard" nonlinearities.

  11. Can low-cost VOR and Omega receivers suffice for RNAV - A new computer-based navigation technique

    NASA Technical Reports Server (NTRS)

    Hollaar, L. A.

    1978-01-01

    It is shown that although RNAV is particularly valuable for the personal transportation segment of general aviation, it has not gained complete acceptance. This is due, in part, to its high cost and the necessary special-handling air traffic control. VOR/DME RNAV calculations are ideally suited for analog computers, and the use of microprocessor technology has been suggested for reducing RNAV costs. Three navigation systems, VOR, Omega, and DR, are compared for common navigational difficulties, such as station geometry, siting errors, ground disturbances, and terminal area coverage. The Kalman filtering technique is described with reference to the disadvantages when using a system including standard microprocessors. An integrated navigation system, using input data from various low-cost sensor systems, is presented and current simulation studies are noted.

  12. Listing's plane and the 3D-VOR in microgravity--the role of the otolith afferences.

    PubMed

    Clarke, Andrew H; Just, K; Krzok, W; Schönfeld, U

    2013-01-01

    The study addresses the question as to what extent the otolith-mediated gravity vector maintains the stability of the coordinate frames of the vestibulo-ocular reflex and the oculomotor system, described by Listing's Plane. Under normal 1 G conditions it has been demonstrated in the monkey that Listing's Plane (LP) and the 3D vestibulo-ocular response (3D-VOR) are close to collinear [10]. In the present study the coordinate frames of the oculomotor system and the three-dimensional vestibulo-ocular reflex (3D-VOR) system were measured under one-g gravity conditions and during a period of prolonged microgravity, on-board the International Space Station (ISS). To this end, the coordinate frame of the oculomotor system is described in Listing's coordinates and that of the 3D-VOR system by the minimal gain vector. The findings demonstrate that under Earthbound, one-g conditions the two coordinate frames diverge by approximately 20° in the human. In the absence of the gravity vector the radical loss in the otolith-mediated contribution to the dynamic VOR leads to a reduction of the torsional VOR component and in turn to a forward tilt of the oculomotor coordinate frame, described by the minimal gain vector. In contrast, the torsional component of LP during horizontal and vertical saccades was found to increase, resulting in a backward tilt of LP. Together with the backward tilt of LP a small but consistent change in LP vergence was observed. The thickness of LP did not appear to change in the absence of gravity. The changes in coordinate frame orientation persisted over the six-month periods spent in zero gravity. The postflight measurements demonstrate that re-adaptation to preflight values proceeds over several days to weeks. The findings demonstrate that the gravity vector represents a common reference for vestibular and oculomotor responses. They also support the idea that the gravity vector provides a central reference for the entire sensorimotor complex. PMID

  13. Adaptation of primate vestibuloocular reflex to altered peripheral vestibular inputs. I. Frequency-specific recovery of horizontal VOR after inactivation of the lateral semicircular canals

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.; Arai, Y.; Suzuki, J.

    1996-01-01

    1. The adaptive plasticity of the vestibuloocular reflex (VOR) following a selective lesion of the peripheral vestibular organs was investigated in rhesus monkeys whose lateral semicircular canals were inactivated by plugging of the canal lumen in both ears. Gain and phase of horizontal, vertical, and torsional slow-phase eye velocity were determined from three-dimensional eye movement recordings obtained acutely after the plugging operation, as well as in regular intervals up to 10 mo later. 2. Acutely after plugging, horizontal VOR was minimal during yaw rotation with gains of < 0.1 at all frequencies. Horizontal VOR gain gradually increased over time, reaching gains of 0.4-0.5 for yaw oscillations at 1.1 Hz approximately 5 mo after lateral canal inactivation. This response recovery was strongly frequency dependent: horizontal VOR gains were largest at the highest frequency tested and progressively decreased for lower frequencies. Below approximately 0.1 Hz, no consistent horizontal VOR could be elicited even 10 mo after plugging. 3. The frequency-dependent changes in gain paralleled changes in horizontal VOR phase. Below approximately 0.1-0.05 Hz large phase leads were present, similarly as in semicircular canal primary afferents. Smaller phase leads were also present at higher frequencies, particularly at 1.1 Hz (the highest frequency tested). 4. Consistent with the afferent-like dynamics of the adapted horizontal VOR, per- and postrotatory horizontal responses to constant-velocity yaw rotations were short lasting. Time constants of the slow-phase eye velocity envelope of the horizontal postrotatory nystagmus were approximately 2 s. Nonetheless, a consistent horizontal optokinetic afternystagmus was evoked in plugged animals. 5. A torsional component that was absent in intact animals was consistently present during yaw rotation acutely after lateral canal inactivation and remained approximately constant thereafter. The frequency response characteristics of this

  14. Visual-vestibular interactions during vestibular compensation: role of the pretectal not in horizontal VOR recovery after hemilabyrinthectomy in rhesus monkey.

    PubMed

    Stewart, C Matthew; Mustari, Michael J; Perachio, Adrian A

    2005-10-01

    Damage to the vestibular labyrinth leads to profound nystagmus and vertigo. Over time, the vestibular-ocular system recovers in a process called vestibular compensation leading to reduced nystagmus and vertigo provided visual signals are available. Our study was directed at identifying sources of visual information that could play a role in vestibular compensation. Specifically, we investigated the role of the pretectal nucleus of the optic tract (NOT) in vestibular compensation after hemilabyrinthectomy (HL) in rhesus monkeys. We chose the NOT because this structure provides critical visual motion information for adaptive modification of the vestibular ocular reflex (VOR). We produced bilateral NOT lesions by injecting the excitotoxin ibotenic acid. We compared vestibular compensation after HL in NOT-lesioned and control animals with intact NOTs. We measured eye movements with an electromagnetic method employing scleral search coils. Measurements included slow-phase eye velocity during spontaneous nystagmus, per- and postrotatory nystagmus and the horizontal VOR (hVOR) gain (eye-velocity/head velocity) associated with per- and postrotatory and sinusoidal (0.2-2.0 Hz; 30-90 degrees/s) whole body oscillation around the earth-vertical axis. VOR gain was low (<0.5) for rotation toward the HL side. Our control animal evinced significant vestibular compensation with VOR gains approaching unity by 100 days post HL. In contrast, monkeys with bilateral lesions of the NOT never obtained this significant recovery with hVOR gains well below unity at 100 days and beyond. Therefore our studies demonstrate that the NOT is an essential source of visual signals for the process of vestibular compensation after HL. PMID:15758055

  15. [Visual tracking with/without passive whole-body rotation in Parkinson's disease (PD): Dissociation of smooth-pursuit and cancellation of vestibulo-ocular reflex (VOR)].

    PubMed

    Ito, Norie; Takei, Hidetoshi; Chiba, Susumu; Inoue, Kiyoharu; Fukushima, Kikuro

    2016-01-01

    Although impaired smooth-pursuit in Parkinson's disease (PD) is well known, reports are conflicting on the ability to cancel vestibulo-ocular reflex (VOR) when the target moves with head, requiring gaze-pursuit. To compare visual tracking performance with or without passive whole-body rotation, we examined eye movements of 10 PD patients and 6 age-matched controls during sinusoidal horizontal smooth-pursuit and passive whole-body rotation (0.3 Hz, ± 10°). Three tasks were tested: smooth-pursuit, VOR cancellation, and VORx1 while subjects fixated an earth-stationary spot during whole-body rotation. Mean ± SD eye velocity gains (eye velocities/stimulus velocities) of PD patients during the 3 tasks were 0.32 ± 0.24 0.25 ± 0.22, 0.85 ± 0.20, whereas those of controls were 0.91 ± 0.06, 0.14 ± 0.07, 0.94 ± 0.05, respectively. Difference was significant between the two subject groups only during smooth-pursuit. Plotting eye-velocity gains of individual subjects during VOR cancellation against those during smooth-pursuit revealed significant negative linear correlation between the two parameters in the controls, but no correlation was found in PD patients. Based on the regression equation of the controls, we estimated expected eye velocity gains of individual subjects during VOR cancellation from their smooth-pursuit gains. Estimated gains of PD patients during VOR cancellation were significantly different from their actual gains, suggesting that different neural mechanisms operate during VOR cancellation in the controls and PD. PMID:26912226

  16. 75 FR 47709 - Amendment of VOR Federal Airways V-8, V-14, V-38, V-47, V-279, and V-422 in the Vicinity of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-09

    ... a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979... U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. ] Sec... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of VOR Federal Airways V-8, V-14,...

  17. 77 FR 9876 - Proposed Modification of VOR Federal Airways V-10, V-12, and V-508 in the Vicinity of Olathe, KS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ... Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and.... 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 2. The... TRANSPORTATION Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Proposed Modification of VOR...

  18. 76 FR 72093 - Amendment of VOR Federal Airways V-81, V-89, and V-169 in the Vicinity of Chadron, NE

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-22

    ... Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR 71.1... Federal Aviation Administration 14 CFR Part 71 RIN 2120-AA66 Amendment of VOR Federal Airways V-81,...

  19. 75 FR 43818 - Amendment of VOR Federal Airways V-50, V-251, and V-313 in the Vicinity of Decatur, IL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-27

    ... Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14...) Domestic VOR Federal Airways. * * * * * V-50 From Hastings, NE; Pawnee City, NE; St. Joseph, MO;...

  20. Experiment K-7-30: Effects of Spaceflight in the Cosmos Biosatellite 2044 on the Vestibular-Ocular Reflex (VOR) of Rhesus Monkeys

    NASA Technical Reports Server (NTRS)

    Cohen, B.; Cohen, N.; Helwig, D.; Solomon, D.; Kozlovskaya, I.; Sirota, M.; Yakushin, S.; Raphan, T.

    1994-01-01

    This technical paper discusses the following: (1) The VOR of two rhesus monkeys was studied before and after 14 days of spaceflight to determine effects of microgravity on the VOR. Horizontal, vertical and roll eye movements were recorded in these and six other monkeys implanted with scleral search coils. Animals were rotated about a vertical axis to determine the gain of the horizontal, vertical and roll VOR. They were rotated about axes tilted from the vertical (off-vertical axis rotation, OVAR) to determine steady state gains and effects of gravity on modulations in eye position and eye velocity. They were also tested for tilt dumping of post-rotatory nystagmus. (2) The gain of the horizontal VOR was close to unity when animals were tested 15 and 18 hours after flight. VOR gain values were similar to those registered before flight. If the gain of the horizontal VOR changes in microgravity, it must revert to normal soon after landing. (3) Steady state velocities of nystagmus induced by off-vertical axis rotation (OVAR) were unchanged by adaptation to microgravity, and the phase of the modulations was similar before and after flight. However, modulations in horizontal eye velocity had more variation after landing and were on mean about 50% larger for angles of tilt of the axis of rotation between 50 and 90?/s after flight. This difference was similar in both animals and was significant. (4) A striking finding was that tilt dumping was lost in the one animal tested for this function. This loss persisted for several days after return. This is reminiscent of the loss of response to pitch while rotating in the M-131 experiments of Skylab, and must be studied in detail in future spaceflights. (5) Thus, two major findings emerged from these studies: after spaceflight the modulation of horizontal eye velocity was larger during OVAR, and one animal lost its ability to tilt-dump its nystagmus. Both findings are consistent with the postulate that adaptation to microgravity

  1. The complete genome sequence and analysis of vB_VorS-PVo5, a Vibrio phage infectious to the pathogenic bacterium Vibrio ordalii ATCC-33509.

    PubMed

    Echeverría-Vega, Alex; Morales-Vicencio, Pablo; Saez-Saavedra, Camila; Ceh, Janja; Araya, Rubén

    2016-01-01

    The bacterium Vibrio ordalii is best known as the causative agent of vibriosis outbreaks in fish and thus recognized for generating serious production losses in aquaculture systems. Here we report for the first time on the isolation and the genome sequencing of phage vB_VorS-PVo5, infectious to Vibrio ordalii ATCC 33509. The features as well as the complete genome sequence and annotation of the Vibrio phage are described; vB_VorS-PVo5 consists of a lineal double stranded DNA totaling ~ 80.6 Kb in length. Considering its ability to lyse Vibrio ordalii ATCC 33509, the phage is likely to gain importance in future aquaculture applications by controlling the pathogen and as such replacing antibiotics as the treatment of choice. PMID:27382430

  2. Model simulation studies to clarify the effect on saccadic eye movements of initial condition velocities set by the Vestibular Ocular Reflex (VOR)

    NASA Technical Reports Server (NTRS)

    Nam, M. H.; Winters, J. M.; Stark, L.

    1981-01-01

    Voluntary active head rotations produced vestibulo-ocular reflex eye movements (VOR) with the subject viewing a fixation target. When this target jumped, the size of the refixation saccades were a function of the ongoing initial velocity of the eye. Saccades made against the VOR were larger in magnitude. Simulation of a reciprocally innervated model eye movement provided results comparable to the experimental data. Most of the experimental effect appeared to be due to linear summation for saccades of 5 and 10 degree magnitude. For small saccades of 2.5 degrees, peripheral nonlinear interaction of state variables in the neuromuscular plant also played a role as proven by comparable behavior in the simulated model with known controller signals.

  3. Kafka's "Vor dem Gesetz": The Case for an Integrated Approach

    ERIC Educational Resources Information Center

    Pickar, Gertrud Bauer

    1975-01-01

    Uses a parable from a Kafka novel to illustrate and support the premise that language and literature study should be integrated, even in the early stages. Reading short literary works can explain involved language problems better than long explanations, and can also stimulate further literary study. (CHK)

  4. Die Anfaenge der Melker Bibliothek - Neue Erkenntnisse zu Handschriften und Fragmenten aus der Zeit vor 1200

    NASA Astrophysics Data System (ADS)

    Glaßner, Christine; Haidinger, Alois

    1996-04-01

    Shortly after Benedictine monks started monastic life in Melk in 1089 the scriptorium was flourishing under abbot Erchenfried (1121-1164). Noteworthy is Cod. 391, a manuscript written in its main part in 1123, but used by the monks as a yearbook with handwritten entries up to the 16th century. This manuscript was also an important source for the publication which dealt with the history of the scriptorium in 12th century. By examining the entries in this book the period of the activity of at least three unknwon writers in this era could be identified. It was the first time that not only the intact volumes but also the manuscripts preserved as fragments in the binding were examined. At the beginning of th 13th century the number of books held in the collection according to the result of this examination was 68. Another remarkable point of the exhibition and of the publication refering to the exhibition was Cod. 412, the oldest manuscript of the monastery, written in early 9th century and containing texts on natural sciences and astronomy by Venerable Bede. Three copies of this manuscript were done during 12th century, one of them probably in Melk, all of them with nearly identical consistency except the catalogue of signs of the zodiac which was ascribed erroneously to Venerable Bede in the Middle Ages: Vatican, Cod. Vat. lat. 643, Zwettl, Cod. 296 (copy of the Vatican manuscript), Klosterneuburg, Cod. 685 (copy of the Zwettl manuscript done in Klosterneuburg). Kurz nach Einführung der Benediktiner in Melk im Jahr 1089 erlebte das Melker Skriptorium unter Abt Erchenfried (1121-1163) seine erste Blüte. Hervorzuheben ist eine im Jahr 1123 angelegte Chronik, die bis in das 16. Jahrhundert durch Annaleneintragungen und andere wichtige Texte zur Geschichte des Klosters ergänzt wurde (Cod. 391). Diese Handschrift ist zugleich eine der wichtigsten Quellen zur Geschichte des Melker Skriptoriums im 12. Jahrhundert, dem sich die Publikation widmet. Mit Hilfe einer genaueren Untersuchung der zeitnahen Eintragungen in diese Handschrift gelang es, die Tätigkeit von zumindest drei wichtigen, im 12. Jahrhundert in Melk identifizierbaren, namentlich nicht bekannten Schreibern chronologisch zuzuordnen. Erstmals wurden die nur fragmentarisch als Makulatur in den Bucheinbänden erhaltenen Handschriften in die Untersuchung einbezogen, so dass für die Wende vom 12. zum 13. Jahrhundert ein Bücherbestand von 68 Handschriften erschlossen werden konnte. Besonders hervorzuheben ist, dass in der Sonderausstellung von 1996 und im Begleitband erstmals eingehend die Bedeutung der ältesten Melker Handschrift, Cod. 412 aus dem frühen 9. Jahrhundert mit naturwissenschaftlichen Texten des Beda Venerabilis, als Vorlage für drei weitere Handschriften diente: Vatikan, Cod. Vat. lat. 643, abgeschrieben wahrscheinlich in Melk, davon abhängig Zwettl, Cod. 296, und Klosterneuburg, Cod. 685. Die Abschriften der Melker Beda-Handschrift sind inhaltlich fast identisch, allerdings um den im Mittelalter fälschlicherweise Beda Venerabilis zugeschriebenen Sternbilderkatalog erweitert.

  5. Der Physik-Nobelpreis vor 100 Jahren Eine neue Eigenschaft der Materie

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2003-11-01

    Im Jahre 1903 erhielten Henri Becquerel sowie Marie und Pierre Curie den Physik-Nobelpreis für die Entdeckung der Radioaktivität. Schon damals stellte Pierre Curie die Frage nach Nutzen und Gefahr dieser neuen Eigenschaft von Materie. Er war der Überzeugung, dass der Fortschritt letztlich mehr zum Nutzen als zum Schaden der Menschen beitrage.

  6. Die Keplersche Supernova - Entdeckung vor 400 Jahren [Kepler's supernova: its discovery 400 years ago

    NASA Astrophysics Data System (ADS)

    Posch, Thomas; Maitzen, Hans Michael

    2004-10-01

    We summarize the early observations of SN 1604 made by Johannes Brunowsky and Johannes Kepler in Prague in October 1604. Quoting from Kepler's two books on this subject ("Gründlicher Bericht" and "De stella nova"), we point out that he compared the supernova with respect to its twinkling with an "exquisite multifaceted diamond" and that he thought this object to be rather something like a newly born (proto-)star than a star in its final phase of evolution, as we would call it today. The twinkling of the star was interpreted by Kepler as intrinsic to it rather than an effect of the Earth's atmosphere.

  7. 76 FR 13083 - Amendment to VOR Federal Airway V-358; TX

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-10

    ... Federal Register amending thirteen Federal airways in the vicinity of Dallas/ Fort Worth, TX (65 FR 61087... (66 FR 50101). The realignment around P-49 was necessary to assist the United States Secret Service in... in the Federal Register amending the V-358 airway description (74 FR 54896). That rule renamed...

  8. Der Physik-Nobelpreis vor 100 Jahren Die Entdeckung des trägen Gases

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2004-11-01

    Im Jahr 1904 erhielt der britische Physiker Lord Rayleigh (John William Strutt, 1842 bis 1919) den Nobelpreis für seine Untersuchungen über die Dichte von Gasen und die Entdeckung des Edelgases Argon.

  9. 76 FR 68674 - Proposed Amendment of VOR Federal Airways V-320 and V-440; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    .... 11-AAL-1 published on April 28, 2011 (76 FR 23687), that amends all Alaska Federal Airways affected... until further notice (76 FR 35097; June 16, 2011). The FAA then determined that V-320 and V-440 did not... rule, to be amended in a future rulemaking (76 FR 65106; October 20, 2011). This action would amend...

  10. D Extention of the Vor Algorithm to Determine and Optimize the Coverage of Geosensor Networks

    NASA Astrophysics Data System (ADS)

    Doodman, S.; Afghantoloee, A.; Mostafavi, M. A.; Karimipour, F.

    2014-10-01

    Recent advances in electrical, mechanical and communication systems have led to development of efficient low-cost and multi-function geosensor networks. The efficiency of a geosensor network is significantly based on network coverage, which is the result of network deployment. Several optimization methods have been proposed to enhance the deployment efficiency and hence increase the coverage, but most of them considered the problem in the 2D environment models, which is usually far from the real situation. This paper extends a Voronoi-based deployment algorithm to 3D environment, which takes the 3D features into account. The proposed approach is applied on two case studies whose results are evaluated and discussed.

  11. 78 FR 2200 - Establishment of VOR Federal Airway V-629; Las Vegas, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-10

    ..., NV. (77 FR 54859). Interested parties were invited to participate in this rulemaking effort by... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory..., 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p.389. Sec. 71.1 0 2. The incorporation...

  12. 78 FR 18232 - Amendment of VOR Federal Airway V-233, Springfield, IL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... depiction of the airway. When V- 233 was amended in the Federal Register of August 8, 2005 (70 FR 45527... Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The...

  13. 78 FR 41686 - Modification of VOR Federal Airway V-345 in the Vicinity of Ashland, WI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-11

    ... modify V-345 in the vicinity of Ashland, WI (78 FR 18271). Interested parties were invited to participate... Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory evaluation..., 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation...

  14. 77 FR 71493 - Amendment of VOR Federal Airway V-8 in the Vicinity of Rifle, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-03

    .... When V-8 was amended in the Federal Register of September 30, 1993 (58 FR 51010), the airway was... aid between Grand Junction, CO, and Kremmling, CO. In the Federal Register of August 9, 2010 (75 FR... ``significant rule'' under Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR...

  15. 75 FR 39149 - Establishment of VOR Federal Airway V-625; Arizona

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-08

    ... Arizona, (74 FR 17911). Interested parties were invited to participate in this rulemaking effort by... ``significant rule'' under Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034..., 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p.389. Sec. 71.1 0 2. The incorporation...

  16. Hydraulische Leitfähigkeiten von Sedimentwürfeln vor und nach einem gefrorenen Zustand

    NASA Astrophysics Data System (ADS)

    Vaitl, Tobias; Gökpinar, Thorsten; Englert, Andreas

    2014-09-01

    To study flow and transport processes in heterogeneous porous media, frozen sediment cubes that were assembled in sandbox experiments may represent a viable procedure. In this investigation, it was important to find out how flow and transport properties would be modified by sediment freezing. In this study, a medium sand, a coarse sand and a fine gravel were investigated to find out to what extent the hydraulic conductivities might change before and after freezing. For this purpose, a cubic Darcy-cell was developed. The results of the study show that it is possible to produce 10 × 10 × 10 cm frozen sediment cubes with the presented apparatus. The study also suggests that freezing and subsequent thawing only caused small changes in hydraulic conductivity of the investigated sediments.

  17. Gain, phase and frequency stability of DSS-42 and DSS-43 vor Voyage Uranus encounter

    NASA Technical Reports Server (NTRS)

    Cha, A. G.; Levy, R.

    1986-01-01

    Theoretically rigorous definitions are derived of such parameters as RF signal path length, phase delay, and phase/frequency stability in a Cassegrainian antenna applicable to a narrow bandwidth channel, as well as algorithms for evaluating these parameters. This work was performed in support of the Voyager spacecraft encounter with Uranus in January 1986. The information was needed to provide Voyager/Uranus radio science researchers with a rotational basis for deciding the best strategy to operate the three antennas involved during the crucial 5-hour occultation period of the encounter. Such recommendations are made at the end of the article.

  18. 76 FR 61257 - Amendment to Description of VOR Federal Airway V-299; CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-04

    ...-2520. See (52 FR 5947; February 27, 1987). The exclusionary wording had previously been included in the description of V-299 (45 FR 335; January 2, 1980). The Rule This action amends Title 14 Code of Federal... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of...

  19. Frequency response of the vestibulo-ocular reflex /VOR/ in the monkey

    NASA Technical Reports Server (NTRS)

    Buettner, U. W.; Henn, V.; Young, L. R.

    1981-01-01

    The frequency response of the vestibulo-ocular reflex has been investigated in the alert monkey during sinusoidal rotation about a vertical axis in a frequency range of 0.001-0.5 Hz. Phase and gain of nystagmus slow phase velocity was determined. In the frequency range above 0.1 Hz, nystagmus slow phase velocity was in phase with (compensated for) head velocity. At lower frequencies, an increasing phase lead was present which could reach more than 90 deg. Gain fell off correspondingly at low frequencies. Calculated time constants were 10-40 s in different monkeys. Animals which had been exposed to numerous previous rotary stimuli in the laboratory showed much shorter time constants than did 'native' monkeys.

  20. 77 FR 23113 - Modification of VOR Federal Airways V-135 and V-137; Southwest United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... in the southwest United States (76 FR 79140). Interested parties were invited to participate in this... Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not...: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p.389....

  1. Fremdsprachliche Moglichkeiten vor der "eigenen Haustur" (Foreign Language Possibilities at One's Own Doorstep)

    ERIC Educational Resources Information Center

    Zydatiss, Wolfgang

    1973-01-01

    Describes an instructional project, How to Tell a Foreigner to Berlin the Way,'' designed to give 8th graders practical experience in using English; format based on the text London--People ans Pictures,'' Cornelsen-Velhagen & Klasing, Berlin. (RS)

  2. 78 FR 37105 - Modification of VOR Federal Airway V-537, GA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-20

    ... Georgia (77 FR 62468). Interested parties were invited to participate in this rulemaking effort by... (SNPRM) (78 FR 21856, April 12, 2013) to reopen the comment period and solicit comments on the proposed... Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979);...

  3. 75 FR 12675 - Amendment of VOR Federal Airway V-422 in the Vicinity of Wolf Lake, IN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-17

    ...'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant...; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by... Vicinity of Wolf Lake, IN AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule....

  4. 75 FR 12674 - Amendment of Jet Routes and VOR Federal Airways in the Vicinity of Gage, OK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-17

    ... Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a Regulatory Evaluation... continues to read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3... Mexico is excluded. * * * * * J-98 From Liberal, KS, via Mitbee, OK; Will Rogers, OK; via Tulsa,...

  5. Die Weichbodenfauna vor der Elbemündung unter dem Einfluß der Klärschlammverklappung

    NASA Astrophysics Data System (ADS)

    Mühlenhardt-Siegel, Ute

    1988-03-01

    Macrobenthic fauna and sediment structure were studied at 6 stations from June 1979 to April 1981. The investigations were carried out in the outer estuary of the River Elbe at depths of 15 38 m near a sewage sludge dumping site. The sediment near this area consisted of a high portion of silt. Usually, very few species and small numbers of individuals were found near that dumping ground. During summer 1980, a mass development of Abra alba and several polychaete species caused an increase in species number which broke down during the following winter. The mass development observed in the study area was apparently not directly caused by the sludge dumping itself, but reflects the natural variability of the community structure. The number of species recorded was significantly correlated with a grain size fraction>31 μm, especially in summer. The seasonal and spatial fluctuation of the benthic community could be well documented by the abundance per species (N/S index). The Shannon-Wiener-Index (H') and eveness (J) were also useful indicators of community variability. The log-normal distribution did not show the seasonal and the spatial differences of the stations. Possible reasons are discussed. The biomass at the stations near the dumping area was less except during the mass development of A. alba. The average individual weight (B/N) was shown to be a good indicator of population fluctuations; polychaete biomass was positively correlated to a grain size fraction≦6 μm, that of molluscs to a grain size fraction>31 μm.

  6. 76 FR 20835 - Amendment of VOR Federal Airways V-1, V-7, V-11 and V-20; Kona, HI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-14

    ... flight inspection. DATES: The effective date of FR Doc. 2011-5078, published on March 10, 2011 (76 FR...: Background Airspace Docket No. 10-AWP-20, published in the Federal Register on March 10, 2011, (76 FR 13082...; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034;...

  7. 76 FR 13082 - Amendment of VOR Federal Airways V-1, V-7, V-11 and V-20; Kona, HI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-10

    ... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation...-11 and V-20; Kona, HI AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule....

  8. 78 FR 1751 - Modification of VOR Federal Airway V-170 in the Vicinity of Devils Lake, ND

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ...-radar separation and airway clearance from the newly established R-5402, Devils Lake, ND (77 FR 54860... (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory evaluation as.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in...

  9. 75 FR 24504 - Proposed Modification of VOR Federal Airways V-82, V-175, V-191, and V-430 in the Vicinity of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-05

    ... Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and..., 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 2. The incorporation...

  10. 77 FR 42625 - Modification of VOR Federal Airways V-10, V-12, and V-508 in the Vicinity of Olathe, KS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-20

    ...-508, in the vicinity of Olathe, KS (77 FR 9876), due to the planned decommissioning of the Johnson... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory.... 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0...

  11. Warum kommt hier NICHT nicht vor? - Regularitaeten beim L-2-Erwerb (Why Is "Nicht" Not Used Here? Regularities in Second Language Acquisition).

    ERIC Educational Resources Information Center

    Stalb, Heinrich

    1978-01-01

    Presents a German test for English students. Errors in the placing of "nicht" are examined and categorized. Criticism of the objectivity of the findings are examined. The tests are seen as a measure of oral skills. Study is recommended of how to present most economically the various items. (IFS/WGA)

  12. 78 FR 19985 - Modification of VOR Federal Airways V-68, V-76, V-194, and V-548 in the Vicinity of Houston, TX

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-03

    ... published in FAA Order 7400.9W (77 FR 50907, August 23, 2012), the FAA is amending the V-68, V-76, V-194... Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not... follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963...

  13. 75 FR 43813 - Modification of VOR Federal Airways V-82, V-175, V-191, and V-430 in the Vicinity of Bemidji, MN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-27

    ... modify V-82, V-175, V-191, and V-430 in the vicinity of Bemidji, MN (75 FR 24504). Interested parties... Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory evaluation...: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p.389....

  14. Curved spaces before Einstein: Karl Schwarzschild's cosmological speculations and the beginnings of relativistic cosmology (German Title: Gekrümmte Universen vor Einstein: Karl Schwarzschilds kosmologische Spekulationen und die Anfänge der relativistischen Kosmologie)

    NASA Astrophysics Data System (ADS)

    Schemmel, Matthias

    In contrast to most of his collegues in astronomy and physics, the German astronomer Karl Schwarzschild immediately recognized the significance of general relativity for physics and astronomy, and played a pioneering role in its early development. In this contribution, it is argued that the clue for understanding Schwarzschild's exceptional reaction to general relativity lies in the study of his prerelativistic work. Long before the rise of general relativity, Schwarzschild occupied himself with foundational problems on the borderline of physics, astronomy, and mathematics that, from today's perspective, belong to the field of problems of that theory. In this contribution, the example of Schwarzschild's early speculations about the non-Euclidean nature of physical space on cosmological scales is presented and their reflection in his reception of general relativity is discussed.

  15. "Onkle Karl" aus Milwaukee: Deutsch-amerikanische Einwandererkultur im Spiegel der Jugendliteratur vor hundert Jahren (Uncle Carl from Milwaukee: German-American Newcomer Culture Reflected in Children's Literature a Hundred Years Ago).

    ERIC Educational Resources Information Center

    Weiss, Gerhard

    1998-01-01

    Examines a late nineteenth-century Milwaukee (Wisconsin) publication for children and young people as a reflection of German-American middle-class culture of the time, showing how the spirit of the 1848 revolution and the experience of the American Civil War shaped German-American intellectuals and how the ideals of freedom and equality dominated…

  16. 14 CFR 171.3 - Requests for IFR procedure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.3 Requests for IFR procedure. (a) Each person who requests an IFR procedure based on a VOR facility that he owns must submit...

  17. 14 CFR 135.165 - Communication and navigation equipment: Extended over-water or IFR operations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... use of the remaining navigation system, and complete an instrument approach and land. (c) VOR navigation equipment. Whenever VOR navigation equipment is required by paragraph (a) or (b) of this...

  18. 14 CFR 171.13 - Reports.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.13 Reports. The owner of each facility to... the appropriate Regional office of the FAA. (d) (e) VOR ground check error data (Forms FAA-2396...

  19. 14 CFR 171.1 - Scope.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.1 Scope. This subpart sets forth minimum requirements for the approval and operation on non-Federal VOR facilities that are to be involved in...

  20. 14 CFR 171.5 - Minimum requirements for approval.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.5 Minimum... approve an IFR procedure for a non-Federal VOR: (1) The facility's performance, as determined by air...

  1. 14 CFR 171.7 - Performance requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.7 Performance requirements. (a) The VOR must perform in accordance with the “International Standards and Recommended Practices... Inspection Manual”, particularly section 201. (e) After January 1, 1975, the owner of the VOR shall...

  2. 14 CFR 171.11 - Maintenance and operations requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... TRANSPORTATION (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.11... instructions for the operation of an air traffic advisory service if the VOR is located outside of controlled... FAA, the owner shall incorporate improvements in VOR maintenance brought about by progress in...

  3. 14 CFR 95.1 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., at which adequate reception of VOR signals is assured. (c) The MCA applies to the operation of an... segment, or other direct route, and adequate reception of VOR navigation signals within 22 nautical miles of a VOR station used to define the route. (f) The MRA applies to the operation of an aircraft...

  4. Oculomotor function during space flight and susceptibility to space motion sickness

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.

    1991-01-01

    Horizontal vestibulo-ocular reflex (VOR) and saccadic eye movements (SEM) were studied in 18 subjects before and during five Space Shuttle missions to evaluate the effects of weightlessness and correlations between results and susceptibility to and actual presence of space motion sickness (SMS). Active sinusoidal head oscillation was the stimulus for VOR tests with vision (VVOR), with eyes shaded (VOR-ES), and VOR suppression (VOR-S). Eye movements were recorded by electrooculography and head position by a potentiometer. No pathological nystagmus or other abnormal eye movements were seen. No significant in-flight changes were seen in the gain, phase shift or waveform of VVOR, VOR-ES or VOR-S. Statistically significant increases in saccadic latency and decreases in saccadic velocity were seen, with no change in saccadic accuracy. Preflight differences between SMS susceptible and nonsusceptible subjects were noted only in VOR-S, with less complete suppression in susceptible subjects, a finding also seen in flight. During flight, VVOR gain was significantly increased in three nonaffected subjects. Saccades of SMS-affected subjects showed increased latency and velocity and decreased accuracy compared to saccades of unaffected subjects.

  5. Studies of the horizontal vestibulo-ocular reflex on STS 7 and 8

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Thomas P.; Pool, Sam L.

    1988-01-01

    Unpaced voluntary horizontal head oscillation was used to study the Vestibulo-Ocular Reflex (VOR) on Shuttle flights STS 7 and 8. Ten subjects performed head oscillations at 0.33 Hz + or - 30 deg amplitude under the followng conditions: VVOR (visual VOR), eyes open and fixed on a stationary target; VOR-EC, with eyes closed and fixed on the same target in imagination; and VOR-S (VOR suppression), with eyes open and fixed on a head-synchronized target. Effects of weightlessness, flight phase, and Space Motion Sickness (SMS) on head oscillation characteristics were examined. A significant increase in head oscillation frequency was noted inflight in subjects free from SMS. In subjects susceptible to SMS, frequency was reduced during their Symptomatic period. The data also suggest that the amplitude and peak velocity of head oscillation were reduced early inflight. No significant changes were noted in reflex gain or phase in any of the test conditions; however, there was a suggestion of an increase in VVOR and VOR-ES gain early inflight in asymptomatic subjects. A significant difference in VOR-S was found between SMS susceptible and non-susceptible subjects. There is no evidence that any changes in VOR characteristics contributed to SMS.

  6. Willkommen, Mr. Chance: Methodologische Betrachtungen zur Gute empirischer Forschung in der Padagogik, diskutiert vor allem an der neueren Untersuchung uber Gewalt von Heitmeyer u.a. (1995) = Welcome, Mr. Chance: Methodological Considerations Concerning the Quality of Empirical Research in Educational Science Based on a Recent Study on Violence Published by Heitmeyer et al. (1995).

    ERIC Educational Resources Information Center

    Wellenreuther, Martin

    1997-01-01

    Argues that the usefulness of strictly quantitative research is still questioned in educational studies, primarily due to deficiencies in methodological training. Uses a critique of a recent study by Heitmeyer et al. (1995) to illustrate the requirements of "good" empirical research. Considers the problems of hypothesis testing in field research.…

  7. Habituation and adaptation of the vestibuloocular reflex: a model of differential control by the vestibulocerebellum.

    PubMed

    Cohen, H; Cohen, B; Raphan, T; Waespe, W

    1992-01-01

    We habituated the dominant time constant of the horizontal vestibuloocular reflex (VOR) of rhesus and cynomolgus monkeys by repeated testing with steps of velocity about a vertical axis and adapted the gain of the VOR by altering visual input with magnifying and reducing lenses. After baseline values were established, the nodulus and ventral uvula of the vestibulocerebellum were ablated in two monkeys, and the effects of nodulouvulectomy and flocculectomy on VOR gain adaptation and habituation were compared. The VOR time constant decreased with repeated testing, rapidly at first and more slowly thereafter. The gain of the VOR was unaffected. Massed trials were more effective than distributed trials in producing habituation. Regardless of the schedule of testing, the VOR time constant never fell below the time constant of the semicircular canals (approximately 5 s). This finding indicates that only the slow component of the vestibular response, the component produced by velocity storage, was habituated. In agreement with this, the time constant of optokinetic after-nystagmus (OKAN) was habituated concurrently with the VOR. Average values for VOR habituation were obtained on a per session basis for six animals. The VOR gain was adapted by natural head movements in partially habituated monkeys while they wore x 2.2 magnifying or x 0.5 reducing lenses. Adaptation occurred rapidly and reached about +/- 30%, similar to values obtained using forced rotation. VOR gain adaptation did not cause additional habituation of the time constant. When the VOR gain was reduced in animals with a long VOR time constant, there were overshoots in eye velocity that peaked at about 6-8 s after the onset or end of constant-velocity rotation. These overshoots occurred at times when the velocity storage integrator would have been maximally activated by semicircular canal input. Since the activity generated in the canals is not altered by visual adaptation, this finding indicates that the gain

  8. Habituation and adaptation of the vestibuloocular reflex: a model of differential control by the vestibulocerebellum

    NASA Technical Reports Server (NTRS)

    Cohen, H.; Cohen, B.; Raphan, T.; Waespe, W.

    1992-01-01

    We habituated the dominant time constant of the horizontal vestibuloocular reflex (VOR) of rhesus and cynomolgus monkeys by repeated testing with steps of velocity about a vertical axis and adapted the gain of the VOR by altering visual input with magnifying and reducing lenses. After baseline values were established, the nodulus and ventral uvula of the vestibulocerebellum were ablated in two monkeys, and the effects of nodulouvulectomy and flocculectomy on VOR gain adaptation and habituation were compared. The VOR time constant decreased with repeated testing, rapidly at first and more slowly thereafter. The gain of the VOR was unaffected. Massed trials were more effective than distributed trials in producing habituation. Regardless of the schedule of testing, the VOR time constant never fell below the time constant of the semicircular canals (approximately 5 s). This finding indicates that only the slow component of the vestibular response, the component produced by velocity storage, was habituated. In agreement with this, the time constant of optokinetic after-nystagmus (OKAN) was habituated concurrently with the VOR. Average values for VOR habituation were obtained on a per session basis for six animals. The VOR gain was adapted by natural head movements in partially habituated monkeys while they wore x 2.2 magnifying or x 0.5 reducing lenses. Adaptation occurred rapidly and reached about +/- 30%, similar to values obtained using forced rotation. VOR gain adaptation did not cause additional habituation of the time constant. When the VOR gain was reduced in animals with a long VOR time constant, there were overshoots in eye velocity that peaked at about 6-8 s after the onset or end of constant-velocity rotation. These overshoots occurred at times when the velocity storage integrator would have been maximally activated by semicircular canal input. Since the activity generated in the canals is not altered by visual adaptation, this finding indicates that the gain

  9. Studies of the horizontal vestibulo-ocular reflex in spaceflight

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Tom; Pool, Sam

    1989-01-01

    Changes in the vestibulo-ocular reflex (VOR) during space flight have been suspected of contributing to space motion sickness. The horizontal VOR was studied in nine subjects on two space shuttle missions. Active unpaced head oscillation at 0.3 Hz was used as the stimulus to examine the gain and phase of the VOR with and without visual input, as well as the visual suppression of the reflex. No statistically significant changes were noted inflight in the gains or phase shifts of the VOR during any test condition, or between space motion sickness susceptible and nonsusceptible populations. Although VOR suppression was unaffected by spaceflight, the space motion sickness-susceptible group tended to exhibit greater error in the suppression than the nonsusceptible group. It is concluded that at this stimulus frequency, VOR gain is unaffected by space-flight, and any minor individual changes do not seem to contribute to space motion sickness.

  10. The effect of retinal image error update rate on human vestibulo-ocular reflex gain adaptation.

    PubMed

    Fadaee, Shannon B; Migliaccio, Americo A

    2016-04-01

    The primary function of the angular vestibulo-ocular reflex (VOR) is to stabilise images on the retina during head movements. Retinal image movement is the likely feedback signal that drives VOR modification/adaptation for different viewing contexts. However, it is not clear whether a retinal image position or velocity error is used primarily as the feedback signal. Recent studies examining this signal are limited because they used near viewing to modify the VOR. However, it is not known whether near viewing drives VOR adaptation or is a pre-programmed contextual cue that modifies the VOR. Our study is based on analysis of the VOR evoked by horizontal head impulses during an established adaptation task. Fourteen human subjects underwent incremental unilateral VOR adaptation training and were tested using the scleral search coil technique over three separate sessions. The update rate of the laser target position (source of the retinal image error signal) used to drive VOR adaptation was different for each session [50 (once every 20 ms), 20 and 15/35 Hz]. Our results show unilateral VOR adaptation occurred at 50 and 20 Hz for both the active (23.0 ± 9.6 and 11.9 ± 9.1% increase on adapting side, respectively) and passive VOR (13.5 ± 14.9, 10.4 ± 12.2%). At 15 Hz, unilateral adaptation no longer occurred in the subject group for both the active and passive VOR, whereas individually, 4/9 subjects tested at 15 Hz had significant adaptation. Our findings suggest that 1-2 retinal image position error signals every 100 ms (i.e. target position update rate 15-20 Hz) are sufficient to drive VOR adaptation. PMID:26715411

  11. Behavior of human horizontal vestibulo-ocular reflex in response to high-acceleration stimuli

    NASA Technical Reports Server (NTRS)

    Maas, E. F.; Huebner, W. P.; Seidman, S. H.; Leigh, R. J.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) during transient, high-acceleration (1900-7100 deg/sec-squared) head rotations was studied in four human subjects. Such stimuli perturbed the angle of gaze and caused illusory movement of a viewed target (oscillopsia). The disturbance of gaze could be attributed to the latency of the VOR (which ranged from 6-15 ms) and inadequate compensatory eye rotations (median VOR gain ranged from 0.61-0.83).

  12. The human sound-evoked vestibulo-ocular reflex and its electromyographic correlate

    PubMed Central

    Welgampola, Miriam S; Migliaccio, Americo A; Myrie, Oluwaseun A; Minor, Lloyd B; Carey, John P

    2009-01-01

    Objective Sound and vibration evoke a short-latency eye movement or “sound-evoked vestibulo-ocular reflex” (VOR) and an infraorbital surface potential: the “ocular vestibular-evoked myogenic potential” (OVEMP). We examined their relationship by measuring the modulation of both responses by gaze and stimulus parameters. Methods In seven subjects with superior semicircular-canal dehiscence (SCD) and six controls, the sound-evoked VOR was measured in 3D using scleral search-coils. OVEMPs were recorded simultaneously, using surface electromyography. Results Eye movement onset (11.6±0.8ms) coincided with the OVEMP peak (12.1±0.35ms). OVEMP and VOR magnitudes were 5-15 times larger in SCD compared with controls. OVEMP amplitudes were maximal on up-gaze and abolished on down-gaze; VOR magnitudes were unaffected. When stimulus type was changed from sound to vibration, OVEMP and VOR changed concordantly: increasing in controls and decreasing in SCD. OVEMP and VOR tuned to identical stimulus frequencies. OVEMP and VOR magnitudes on up-gaze were significantly correlated (R=0.83-0.97). Conclusion Selective decrease of the OVEMP upon down-gaze is consistent with relaxation or retraction of the inferior oblique muscles. The temporal relationship of OVEMP and VOR and their identical modulation by external factors confirms a common origin. Significance Sound-evoked OVEMP and VOR represent the electrical and mechanical correlates of the same vestibulo-ocular response. PMID:19070541

  13. The variable gain element of the vestibulo-ocular reflex is common to the optokinetic system of the cat.

    PubMed

    Demer, J L

    1981-12-14

    The gain (slow-phase eye velocity/head velocity) of the vestibulo-ocular reflex (VOR) of 6 alert cats was sequentially adapted to values between 0.2 and 1.66 by the chronic wearing of visual reversing or 2 X magnifying spectacles, combined with forced rotation in the light. Gain was measured during sinusoidal oscillation in darkness at 0.05 Hz at a peak velocity of about 30 degrees/s. In each state of VOR gain adaptation, optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN) were measured in a full-field optokinetic drum at velocities of 20-80 degrees/s. Steady-state, slow-phase, optokinetic eye velocity nearly equaled low drum velocities, but saturated at higher velocities and declined when drum velocity further increased. The saturation velocity varied in relation to VOR gain, ranging from 10-20 degrees/s at a VOR gain of 0.2-0.4, to 65 degrees/s at a VOR gain of 1.66. The means that the variable gain element of the VOR is shared by the optokinetic system (OKS). OKAN, measured in darkness, had a roughly exponential decay. The time constant of OKAN (Tokan) also varied with VOR gain, ranging form about 2 s at a VOR gain of 0.2, to 10 s at a VOR gain of 1.66. This is a novel finding which suggests that the velocity-storage mechanism was also affected by gain changes. A model is proposed in which a neural, variable-gain element is located in a positive-feedback, velocity-storage loop common to both the VOR and the OKS. Computer simulation showed that this hypothesis could account for most of the observed changes in OKN saturation and Tokan with changes in VOR gain. The model also predicts that low frequency VOR phase lead in darkness should increase with decreasing VOR gain. Experimental VOR phase lead at 0.05 Hz varied from about 10 degrees for VOR gains above 1.1 to about 50 degrees for VOR gains below 0.3. Such phase-lead data agree with the trend predicted by the model. PMID:6975645

  14. 75 FR 52437 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... VOR/DME 17500 TOKEE, AK FIX 5700 TOKEE, AK FIX FLIPS, AK FIX 6300 17500 FLIPS, AK FIX BIORKA ISLAND... Sec. 95.3280 RNAV Route T280 Is Amended To Read in Part FLIPS, AK FIX LEVEL ISLAND, AK VOR/DME...

  15. 14 CFR 91.161 - Special awareness training required for pilots flying under visual flight rules within a 60...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... pilots flying under visual flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME... Rules Visual Flight Rules § 91.161 Special awareness training required for pilots flying under visual... of an aircraft while flying within a 60-nautical mile radius of the DCA VOR/DME, under VFR,...

  16. 14 CFR 91.161 - Special awareness training required for pilots flying under visual flight rules within a 60...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... pilots flying under visual flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME... Rules Visual Flight Rules § 91.161 Special awareness training required for pilots flying under visual... of an aircraft while flying within a 60-nautical mile radius of the DCA VOR/DME, under VFR,...

  17. 75 FR 42308 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-21

    ... Policies and Procedures (44 FR 11034; February 26,1979); and (3) does not warrant preparation of a... Obstacle DP, Amdt 3 Matoon/Charleston, IL, Coles County Memorial, NDB RWY 29, Amdt 5A Matoon/Charleston, IL, Coles County Memorial, VOR RWY 6, Amdt 13A Matoon/Charleston, IL, Coles County Memorial, VOR RWY...

  18. 75 FR 8241 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-24

    ... Policies and Procedures (44 FR 11034; February 26,1979); and (3) does not warrant preparation of a..., VOR/DME RWY 9, Amdt 3 On January 28, 2010 (75 FR 18) the FAA published an Amendment in Docket No... Airpark, RNAV (GPS) RWY 9, Amdt 1 Atlanta, GA, Newman Coweta County, VOR/DME-A, Amdt 8 Le Mars, IA,...

  19. 75 FR 82228 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-30

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... MEA Youngstown, OH VORTAC Volan, PA FIX *5000 *3000--MOCA *3000--GNSS MEA Volan, PA FIX Talls, PA FIX *5000 *3200--MOCA *3300--GNSS MEA Talls, PA FIX Revloc, PA VOR/DME...... 4100 Sec. 95.6026 VOR...

  20. 77 FR 3091 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-23

    ... 3091-3098] [FR Doc No: 2012-1046] DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR... not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26... VOR/DME Anchorage, AK VOR/DME......... 103 Kodiak [FR Doc. 2012-1046 Filed 1-20-12; 8:45 am]...

  1. 78 FR 67024 - Establishment of Class E Airspace; Glasgow, MT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-08

    ... airspace at the Glasgow VOR/DME navigation aid, Glasgow, MT (78 FR 59807, September 30, 2013). The FAA... Federal Register of September 30, 2013 (78 FR 59807), Airspace Docket No. 13- ANM-17, FR Doc. 2013-23669... airspace at the Glasgow VHF Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME)...

  2. Auf der Suche nach extrasolaren Transitplaneten

    NASA Astrophysics Data System (ADS)

    Heller, René

    2010-06-01

    Planeten um andere Sonnen, die von der Erde aus gesehen einmal während ihres Orbits vor ihrem Zentralstern vorbeiziehen, eröffnen eine bis vor Kurzem ungeahnte Palette an Möglichkeiten zu ihrer Untersuchung. Nur: Wo am Himmel lassen sich diese Kandidaten für Sternbedeckungen eigentlich finden?

  3. The Neural Basis for Learning of Simple Motor Skills.

    ERIC Educational Resources Information Center

    Lisberger, Stephen G.

    1988-01-01

    Discusses the vestibulo-ocular reflex (VOR) which is used to investigate the neural basis for motor learning in monkeys. Suggests organizing principles that may apply in forms of motor learning as a result of similarities among VOR and other motor systems. (Author/RT)

  4. Multiple source navigation signal generator

    NASA Astrophysics Data System (ADS)

    Bojda, Petr

    2010-09-01

    The paper presents a FPGA based digital VOR/LOC signal generator. It provides the composite signal, which consists of the particular signals of several predefined navigation sources - VOR beacons. Design of the generator is implemented into the two different FPGA DSP platforms.

  5. Vestibulo-Ocular Response and Balance Control in Children and Young Adults with Mild-to-Moderate Intellectual and Developmental Disability: A Pilot Study

    ERIC Educational Resources Information Center

    Zur, Oz; Ronen, Ayelet; Melzer, Itshak; Carmeli, Eli

    2013-01-01

    The vestibulo-ocular response (VOR) may not be fully developed in children with an intellectual and developmental disability (IDD). This study aimed to identify the presence of VOR deficit in children and young adults with unspecified mild-to-moderate intellectual and developmental disability and its effect on balance control. Twenty-one children…

  6. Thin Clients: Anwendungsvirtualisierung (SBC) oder Desktop-Virtualisierung?

    NASA Astrophysics Data System (ADS)

    von Lamp, Frank

    Mit Thin Clients lassen sich verschiedene auf Virtualisierung basierende Infrastrukturen unterstützen, die jeweils unterschiedliche Vor- und Nachteile besitzen. Dieser Beitrag stellt die wichtigsten Vor- und Nachteile von Server Based Computing und Desktop-Virtualisierung mit Thin Clients gegenüber.

  7. Functional organization of primate translational vestibulo-ocular reflexes and effects of unilateral labyrinthectomy

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; McHenry, M. Q.; Newlands, S. D.; Dickman, J. D.

    1999-01-01

    Translational vestibulo-ocular reflexes (trVORs) are characterized by distinct spatio-temporal properties and sensitivities that are proportional to the inverse of viewing distance. Anodal (inhibitory) labyrinthine stimulation (100 microA, < 2 s) during motion decreased the high-pass filtered dynamics, as well as horizontal trVOR sensitivity and its dependence on viewing distance. Cathodal (excitatory) currents had opposite effects. Translational VORs were also affected after unilateral labyrinthectomy. Animals lost their ability to modulate trVOR sensitivity as a function of viewing distance acutely after the lesion. These deficits partially recovered over time, albeit a significant reduction in trVOR sensitivity as a function of viewing distance remained in compensated animals. During fore-aft motion, the effects of unilateral labyrinthectomy were more dramatic. Both acute and compensated animals permanently lost their ability to modulate fore-aft trVOR responses as a function of target eccentricity. These results suggest that (1) the dynamics and viewing distance-dependent properties of the trVORs are very sensitive to changes in the resting firing rate of vestibular afferents and, consequently, vestibular nuclei neurons; (2) the most irregularly firing primary otolith afferents that are most sensitive to labyrinthine electrical stimulation might contribute to reflex dynamics and sensitivity; (3) inputs from both labyrinths are necessary for the generation of the translational VORs.

  8. Plasticity within non-cerebellar pathways rapidly shapes motor performance in vivo

    PubMed Central

    Mitchell, Diana E.; Della Santina, Charles C.; Cullen, Kathleen E.

    2016-01-01

    Although cerebellar mechanisms are vital to maintain accuracy during complex movements and to calibrate simple reflexes, recent in vitro studies have called into question the widely held view that synaptic changes within cerebellar pathways exclusively guide alterations in motor performance. Here we investigate the vestibulo-ocular reflex (VOR) circuitry by applying temporally precise activation of vestibular afferents in awake-behaving monkeys to link plasticity at different neural sites with changes in motor performance. Behaviourally relevant activation patterns produce rapid attenuation of direct pathway VOR neurons, but not their nerve input. Changes in the strength of this pathway are sufficient to induce a lasting decrease in the evoked VOR. In addition, indirect brainstem pathways display complementary nearly instantaneous changes, contributing to compensating for the reduced sensitivity of primary VOR neurons. Taken together, our data provide evidence that multiple sites of plasticity within VOR pathways can rapidly shape motor performance in vivo. PMID:27157829

  9. Light conditions affect the roll-induced vestibuloocular reflex in Xenopus laevis tadpoles

    NASA Astrophysics Data System (ADS)

    El-Yamany, Nabil A.

    2008-12-01

    In Xenopus laevis tadpoles, effects of asymmetrical light conditions on the roll-induced vestibuloocular reflex (rVOR) were tested for the developmental period between stage 47 and 49. For comparison, the rVOR was tested in dim- and high-symmetrical light environments. Test parameters were the rVOR gain and rVOR amplitude. Under all light conditions, the rVOR increased from tadpole stage 47 to 49. For all stages, the asymmetrical light field induced the strongest response, the dim light field the weakest one. The response for the left and right eye was identical, even if the tadpoles were tested under asymmetrical light conditions. The experiments can be considered as hints (1) for an age-dependent light sensitivity of vestibular neurons, and (2) for the existence of control systems for coordinated eye movements that has its origin in the proprioceptors of the extraocular eye muscles.

  10. Age-related changes in human vestibulo-ocular and optokinetic reflexes: Pseudorandom rotation tests

    NASA Technical Reports Server (NTRS)

    Peterka, R. J.; Black, F. O.; Schoenhoff, M. B.

    1989-01-01

    The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR and OKR reflex dynamics, and to identify the distributions of parameters which describe VOR and OKR responses to pseudorandom stimuli in a putatively normal population. In general, VOR and OKR response parameters changed in a manner consistent with declining function with increasing age. For the VOR this was reflected in declining response amplitudes, although the magnitude of the decline was small relative to the variability of the data. For the OKR the lag time of the response, probably associated with the time required for visual information processing, increased linearly with age at a rate of about 1 ms per year.

  11. Effects of adaptation of vestibulo-ocular reflex function on manual target localization

    NASA Technical Reports Server (NTRS)

    Bloomberg, J. J.; Merkle, L. A.; Barry, S. R.; Huebner, W. P.; Cohen, H. S.; Mueller, S. A.; Fordice, J.

    2000-01-01

    The goal of the present study was to determine if adaptive modulation of vestibulo-ocular reflex (VOR) function is associated with commensurate alterations in manual target localization. To measure the effects of adapted VOR on manual responses we developed the Vestibular-Contingent Pointing Test (VCP). In the VCP test, subjects pointed to a remembered target following passive whole body rotation in the dark. In the first experiment, subjects performed VCP before and after wearing 0.5X minifying lenses that adaptively attenuate horizontal VOR gain. Results showed that adaptive reduction in horizontal VOR gain was accompanied by a commensurate change in VCP performance. In the second experiment, bilaterally labyrinthine deficient (LD) subjects were tested to confirm that vestibular cues were central to the spatial coding of both eye and hand movements during VCP. LD subjects performed significantly worse than normal subjects. These results demonstrate that adaptive change in VOR can lead to alterations in manual target localization.

  12. Plasticity within non-cerebellar pathways rapidly shapes motor performance in vivo.

    PubMed

    Mitchell, Diana E; Della Santina, Charles C; Cullen, Kathleen E

    2016-01-01

    Although cerebellar mechanisms are vital to maintain accuracy during complex movements and to calibrate simple reflexes, recent in vitro studies have called into question the widely held view that synaptic changes within cerebellar pathways exclusively guide alterations in motor performance. Here we investigate the vestibulo-ocular reflex (VOR) circuitry by applying temporally precise activation of vestibular afferents in awake-behaving monkeys to link plasticity at different neural sites with changes in motor performance. Behaviourally relevant activation patterns produce rapid attenuation of direct pathway VOR neurons, but not their nerve input. Changes in the strength of this pathway are sufficient to induce a lasting decrease in the evoked VOR. In addition, indirect brainstem pathways display complementary nearly instantaneous changes, contributing to compensating for the reduced sensitivity of primary VOR neurons. Taken together, our data provide evidence that multiple sites of plasticity within VOR pathways can rapidly shape motor performance in vivo. PMID:27157829

  13. Application of alkyl polyglycoside surfactant in ultrasonic-assisted extraction followed by macroporous resin enrichment for the separation of vitexin-2″-O-rhamnoside and vitexin from Crataegus pinnatifida leaves.

    PubMed

    Han, Feng; Guo, Yupin; Gu, Huiyan; Li, Fenglan; Hu, Baozhong; Yang, Lei

    2016-02-15

    An alkyl polyglycoside (APG) surfactant was used in ultrasonic-assisted extraction to effectively extract vitexin-2″-O-rhamnoside (VOR) and vitexin (VIT) from Crataegus pinnatifida leaves. APG0810 was selected as the surfactant. The extraction process was optimized for ultrasonic power, the APG concentration, ultrasonic time, soaking time, and liquid-solid ratio. The proposed approach showed good recovery (99.80-102.50% for VOR and 98.83-103.19% for VIT) and reproducibility (relative standard deviation, n=5; 3.7% for VOR and 4.2% for VIT) for both components. The proposed sample preparation method is both simple and effective. The use of APG for extraction of key herbal ingredients shows great potential. Ten widely used commercial macroporous resins were evaluated in a screening study to identify a suitable resin for the separation and purification of VOR and VIT. After comparing static and dynamic adsorption and desorption processes, HPD100B was selected as the most suitable resin. After column adsorption and desorption on this resin, the target compounds VOR and VIT can be effectively separated from the APG0810 extraction solution. Recoveries of VOR and VIT were 89.27%±0.42% and 85.29%±0.36%, respectively. The purity of VOR increased from 35.0% to 58.3% and the purity of VIT increased from 12.5% to 19.9%. PMID:26807707

  14. Contribution of irregular semicircular canal afferents to the horizontal vestibuloocular response during constant velocity rotation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Perachio, A. A.

    1993-01-01

    1. The effects of constant anodal currents (100 microA) delivered bilaterally to both labyrinths on the horizontal vestibuloocular response (VOR) were studied in squirrel monkeys during steps of angular velocity in the dark. We report that bilateral anodal currents decreased eye velocity approximately 30-50% during the period of galvanic stimulation without a change in the time constant of VOR. The decrease in eye velocity, present during steps of angular velocity, was not observed during sinusoidal head rotation at 0.2, 0.5, and 1 Hz. The results suggest that responses from irregular vestibular afferents influence VOR amplitude during constant velocity rotation.

  15. A Sparse Matrix Approach for Simultaneous Quantification of Nystagmus and Saccade

    NASA Technical Reports Server (NTRS)

    Kukreja, Sunil L.; Stone, Lee; Boyle, Richard D.

    2012-01-01

    The vestibulo-ocular reflex (VOR) consists of two intermingled non-linear subsystems; namely, nystagmus and saccade. Typically, nystagmus is analysed using a single sufficiently long signal or a concatenation of them. Saccade information is not analysed and discarded due to insufficient data length to provide consistent and minimum variance estimates. This paper presents a novel sparse matrix approach to system identification of the VOR. It allows for the simultaneous estimation of both nystagmus and saccade signals. We show via simulation of the VOR that our technique provides consistent and unbiased estimates in the presence of output additive noise.

  16. Earth horizontal axis rotational responses in patients with unilateral peripheral vestibular deficits

    NASA Technical Reports Server (NTRS)

    Furman, Joseph M. R.; Kamerer, Donald B.; Wall, Conrad, III

    1989-01-01

    The vestibulo-ocular reflex (VOR) of five patients with surgically confirmed unilateral peripheral vestibular lesions is evaluated. Testing used both earth vertical axis (EVA) and earth horizontal axis (EHA) yaw rotation. Results indicated that the patients had short VOR time constants, asymmetric responses to both EVA and EHA rotation, and normal EHA modulation components. These findings suggest that unilateral peripheral vestibular loss causes a shortened VOR time constant even with the addition of dynamic otolithic stimulation and causes an asymmetry in semicircular canal-ocular reflexes and one aspect of otolith-ocular reflexes.

  17. High-Velocity Angular Vestibulo-Ocular Reflex Adaptation to Position Error Signals

    PubMed Central

    Scherer, Matthew; Schubert, Michael C.

    2010-01-01

    Background and Purpose Vestibular rehabilitation strategies including gaze stabilization exercises have been shown to increase gain of the angular vestibulo-ocular reflex (aVOR) using a retinal slip error signal (ES). The identification of additional ESs capable of promoting substitution strategies or aVOR adaptation is an important goal in the management of vestibular hypofunction. Position ESs have been shown to increase both aVOR gain and recruitment of compensatory saccades (CSs) during passive whole body rotation. This may be a useful compensatory strategy for gaze instability during active head rotation as well. In vestibular rehabilitation, the imaginary target exercise is often prescribed to improve gaze stability. This exercise uses a position ES; however, the mechanism for its effect has not been investigated. We compared aVOR gain adaptation using 2 types of small position ES: constant versus incremental. Methods Ten subjects with normal vestibular function were assessed with unpredictable and active head rotations before and after a 20-minute training session. Subjects performed 9 epochs of 40 active, high-velocity head impulses using a position ES stimulus to increase aVOR gain. Results Five subjects demonstrated significant aVOR gain increases with the constant-position ES (mean, 2%; range, −18% to 12%) compared with another 5 subjects showing significant aVOR gain increases to the incremental-position ES (mean, 3.7%; range, −2% to 22.6%). There was no difference in aVOR gain adaptation or CS recruitment between the 2 paradigms. Discussion and Conclusion These findings suggest that some subjects can increase their aVOR gain in response to high-velocity active head movement training using a position ES. The primary mechanism for this seems to be aVOR gain adaptation because CS use was not modified. The overall low change in aVOR gain adaptation with position ES suggests that retinal slip is a more powerful aVOR gain modifier. PMID:20588093

  18. 78 FR 64172 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-28

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26,1979); and (3) does... Muni, VOR/DME RWY 15, Amdt 8 Savanna, IL, Tri-Township, RNAV (GPS) RWY 13, Orig-A Rocky Mount,...

  19. 76 FR 46202 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-02

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... Seminole, FL VORTAC Pecan, GA VORTAC........ 2100 Sec. 95.6119 VOR Federal Airway V119 Is Amended To...

  20. Evaluation of Microwave Landing System (MLS) effect on the delivery performance of a fixed-path metering and spacing system

    NASA Technical Reports Server (NTRS)

    Credeur, L.; Davis, C. M.; Capron, W. R.

    1981-01-01

    Metering and spacing (M & S) system's algorithms described assume an aircraft two dimensional are navigation capability. The three navigation systems compared were: very high frequency omnidirectional range/distance measuring equipment (VOR/DME) and ILS, VOR/DME and + or - 40 MLS, and VOR/DME and + or - 60 MLS. Other factors studied were M & S tentative schedule point location, route geometry effects, and approach gate location effects. Summarized results are: the MLS offers some improvement over VOR/DME and ILS if all approach routes contain computer assisted turns; pilot reaction to moving the gate closer to the runway threshold may adversely affect M & S performance; and coupling en route metering to terminal scheduling transfers most of the terminal holding to more full efficient, higher altitude en route delay.

  1. 78 FR 47047 - Proposed Policy for Discontinuance of Certain Instrument Approach Procedures

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-02

    ... network (MON) initiative. Proposed Policy The NDB and VOR IAPs recommended for cancellation would be... Federal Aviation Administration Proposed Policy for Discontinuance of Certain Instrument Approach Procedures AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed policy and...

  2. 75 FR 40720 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... MEA Sec. 95.6056 VOR FEDERAL AIRWAY V56 IS AMENDED TO READ IN PART MACON, GA VORTAC MISTY, GA...

  3. 76 FR 21622 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-18

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... 17500 THEDFORD, NE VOR/DME MARSS, NE FIX 4900 17500 MARSS, NE FIX VALENTINE, NE NDB 4800 17500...

  4. 75 FR 65938 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a.../10 VOR Rwy 34, Amdt 4D. Green State. 18-Nov-10 FL Hollywood North Perry........ 0/7474 10/5/10...

  5. Spatial Transformation of the Vestibulo-Ocular Reflex during Spaceflight

    NASA Technical Reports Server (NTRS)

    Clement, Gilles; Wood, Scott J.; Reschke, Millard F.

    1996-01-01

    It was hypothesized that the absence of the gravitational reference cues may be responsible for adaptive changes in the vestibulo-ocular reflex (VOR). These changes result in the alteration of the direction of the compensatory slow phase (SP) eye movements in microgravity. In order to test this hypothesis, the direction of the VOR SP relative to head motion was investigated in three astronauts during and after an eight-day orbital flight by passive sinusoidal pitch or yaw angular motion at two frequencies. The results of the inflight and postflight testing are considered. The observed deviation between VOR SP and head motion suggests that spatial transformation in the VOR occurred during adaptation to microgravity. It is considered that, although this spatial transformation might be due to a sensory bias, it may reflect central changes in the reference system used for spatial orientation in microgravity.

  6. Unfälle mit Pkw

    NASA Astrophysics Data System (ADS)

    Burg, Heinz

    Der Verkehrsunfall ereignete sich innerorts auf einer Kreuzung mit rechts vor links Regelung. Es galt dort die allgemeine Geschwindigkeitsbegrenzung auf 50 km/h. Zur Unfallzeit war es hell und trocken. Die Fahrbahn hatte eine Schwarzdecke.

  7. Canal and otolith vestibulo-ocular reflexes to vertical and off vertical axis rotations in children learning to walk.

    PubMed

    Wiener-Vacher, S R; Toupet, F; Narcy, P

    1996-09-01

    In order to determine the characteristics of the vestibulo-ocular reflexes (VORs) as a function of age and posturo-motor development, a group of 26 normal children (6 to 25 months old) were tested at three different stages of posturo-motor control: prior to as well as during the first attempts to walk without support, and during the first year of independent walking. The test consisted of electro-oculographic (EOG) recordings of the VOR responses to horizontal semi-circular canal and otolith stimulations. The canal VOR was elicited in seated subjects by rotatory impulsions about a vertical axis (acceleration and deceleration both at 40 degrees/s2, separated by a rotation at 60 degrees/s velocity). The otolith VOR was elicited by inclining the rotating chair by 9 degrees respect to gravity. For the canal VOR, the time constant and the highest initial slow phase velocity were measured. The otolith VOR was characterized by the amplitude of the modulation and the bias (offset of baseline from zero) of the slow phase velocity averaged over 10 to 20 rotation cycles, for both the horizontal and vertical components of the response. The pooled values of these data show that canal VOR parameters did not vary significantly either with age of the children or with their stage of posturo-motor control. However, the otolith VOR parameters changed during the period of learning to walk: the modulation of the horizontal component increased and the modulation of the vertical component decreased significantly. Thus the ability to walk without support is marked by a significant change in the otolith but not canal responses; since the vestibular sensory organs develop anatomically at the same rate these results indicate that central nervous system processors of canal and otolith information develop independently. PMID:8908240

  8. An Investigation of Horizontal Combined Eye-Head Tracking in Patients with Abnormal Vestibular and Smooth Pursuit Eye Movements

    NASA Technical Reports Server (NTRS)

    Huebner, William P.; Leigh, R. John; Seidman, Scott H.; Billian, Carl

    1993-01-01

    We investigated the interaction of smooth ocular pursuit (SP) and the vestibulo-ocular reflex (VOR) during horizontal, combined eye-head tracking (CEHT) in patients with abnormalities of either the VOR or SP movements. Our strategy was to apply transient stimuli that capitalized on the different latencies to onset of SP and the VOR. During CEHT of a target moving at 15 deg/sec, normal subjects and patients with VOR deficits all tracked the target with a gain close to 1.O. When the heads of normal subjects were suddenly and unexpectedly braked to a halt during CEHT, the eye promptly began to move in the orbit to track the target, but eye-in-orbit velocity transiently fell to about 60-70% of target velocity. In patients with deficient labyrinthine function, following the onset of the head brake, eye movements to track the target were absent, and SP movements were not generated until about 100 msec later. In patients with deficient SP, CEHT was superior to SP tracking with the head stationary; after the onset of the head brake, tracking eye movements were initiated promptly, but eye velocity was less than 50% of target velocity and increased only slightly thereafter. These results indicate that at least two mechanisms operate to overcome the VOR and allow gaze to track the target during CEHT: (1) the SP system provides a signal to cancel a normally-operating VOR (this cancellation signal is not needed by labyrinthine-deficient patients who have no VOR to cancel), and (2) a reduction of the gain of the VOR is achieved, an ability that is preserved even in patients with cerebral lesions that impair SP.

  9. Epidemiology of Vestibulo-Ocular Reflex Function: Data from the Baltimore Longitudinal Study of Aging

    PubMed Central

    Li, Carol; Layman, Andrew J.; Geary, Robert; Anson, Eric; Carey, John P.; Ferrucci, Luigi; Agrawal, Yuri

    2014-01-01

    Objective To determine age-related changes in vestibulo-ocular reflex (VOR) function in community-dwelling adults, and evaluate these for associations with demographic characteristics and cardiovascular risk factors. Study Design Cross-sectional analysis within the Baltimore Longitudinal Study of Aging (BLSA), a longitudinal prospective cohort study. Setting Vestibular testing laboratory within an acute care teaching hospital. Patients Community-dwelling adults enrolled in the BLSA. Intervention(s) Horizontal VOR gain measurement using video head-impulse testing and visual acuity testing. Main Outcome Measure(s) VOR gain was calculated as the ratio of eye velocity to head velocity. Demographic and cardiovascular risk factor data were collected through study questionnaires. Results One hundred nine subjects were analyzed with mean age (SD) 69.9 years (14.2), with a range from 26 to 92 years. VOR gain remained stable from age 26 to 79 after which it significantly declined at a rate of 0.012/year (p = 0.033) in adjusted analyses. Individuals aged 80 years or older had a nearly 8-fold increased odds of VOR gain less than 0.80 relative to those aged less than 80 years in multivariate models (prevalence of 13.2% vs. 2.8%; OR 7.79, 95% CI: 1.04–58.38). Otherwise, VOR gain did not differ significantly across demographic or cardiovascular risk groups. Conclusion We report age-related decline in VOR function in individuals aged 80 years and older. Further analyses are in progress to establish the significance of these VOR abnormalities to functional and mobility outcomes in older individuals. PMID:25275869

  10. Physik gestern und heute Von der Metallstange zum Hochenergielaser

    NASA Astrophysics Data System (ADS)

    Heering, Peter

    2002-05-01

    Im Mai 1752 wurde in Marly bei Paris auf Anregung des amerikanischen Forschers und Politikers Benjamin Franklin erstmals die elektrische Natur des Blitzes nachgewiesen. Damals beschrieb Franklin auch eine technische Vorrichtung, die als Schutz von Gebäuden vor Blitzschlägen dienen sollte: den Blitzableiter. Diese aus heutiger Sicht scheinbar triviale Vorrichtung wurde aber keineswegs unmittelbar akzeptiert. Und bis heute ist die Forschung zum Schutz von Einrichtungen vor Blitzschlägen nicht abgeschlossen.

  11. Vestibulo-ocular reflex of the squirrel monkey during eccentric rotation with centripetal acceleration along the naso-occipital axis.

    PubMed

    Merfeld, D M

    1996-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in four male squirrel monkeys. Monkeys were rotated in the dark at 200 degrees/s, centrally or 79 cm off-axis, with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's position relative to the centripetal acceleration (facing center or back to center) had a dramatic influence on the VOR. These studies show that a torsional response was always elicited that acted to shift the axis of eye rotation toward alignment with gravito-inertial force. On the other hand, a slow phase downward vertical response usually existed, which shifted the axis of eye rotation away from the gravito-inertial force. These findings were consistent across all monkeys. In another set of tests, the same monkeys were rapidly tilted about their interaural (pitch) axis. Tilt orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the rotation, no consistent eye velocity response was ever observed during or following the tilt. The absence of any response following tilt proves that the observed torsional and vertical responses were not a positional nystagmus. Model simulations qualitatively predict all components of these eccentric rotation and tilt responses. These simulations support the conclusion that the VOR during eccentric rotation may consist of two components: a linear VOR and a rotational VOR. The model predicts a slow phase downward, vertical, linear VOR during eccentric rotation even though there was never a change in the force aligned with monkey's spinal (Z) axis. The model also predicts the torsional components of the response that shift the rotation axis of the angular VOR toward alignment with gravito-inertial force

  12. Behavioral analysis of signals that guide learned changes in the amplitude and dynamics of the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Raymond, J. L.; Lisberger, S. G.

    1996-01-01

    We characterized the dependence of motor learning in the monkey vestibulo-ocular reflex (VOR) on the duration, frequency, and relative timing of the visual and vestibular stimuli used to induce learning. The amplitude of the VOR was decreased or increased through training with paired head and visual stimulus motion in the same or opposite directions, respectively. For training stimuli that consisted of simultaneous pulses of head and target velocity 80-1000 msec in duration, brief stimuli caused small changes in the amplitude of the VOR, whereas long stimuli caused larger changes in amplitude as well as changes in the dynamics of the reflex. When the relative timing of the visual and vestibular stimuli was varied, brief image motion paired with the beginning of a longer vestibular stimulus caused changes in the amplitude of the reflex alone, but the same image motion paired with a later time in the vestibular stimulus caused changes in the dynamics as well as the amplitude of the VOR. For training stimuli that consisted of sinusoidal head and visual stimulus motion, low-frequency training stimuli induced frequency-selective changes in the VOR, as reported previously, whereas high-frequency training stimuli induced changes in the amplitude of the VOR that were more similar across test frequency. The results suggest that there are at least two distinguishable components of motor learning in the VOR. One component is induced by short-duration or high-frequency stimuli and involves changes in only the amplitude of the reflex. A second component is induced by long-duration or low-frequency stimuli and involves changes in the amplitude and dynamics of the VOR.

  13. Vestibulo-ocular reflex of the squirrel monkey during eccentric rotation with centripetal acceleration along the naso-occipital axis

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1996-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in four male squirrel monkeys. Monkeys were rotated in the dark at 200 degrees/s, centrally or 79 cm off-axis, with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's position relative to the centripetal acceleration (facing center or back to center) had a dramatic influence on the VOR. These studies show that a torsional response was always elicited that acted to shift the axis of eye rotation toward alignment with gravito-inertial force. On the other hand, a slow phase downward vertical response usually existed, which shifted the axis of eye rotation away from the gravito-inertial force. These findings were consistent across all monkeys. In another set of tests, the same monkeys were rapidly tilted about their interaural (pitch) axis. Tilt orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the rotation, no consistent eye velocity response was ever observed during or following the tilt. The absence of any response following tilt proves that the observed torsional and vertical responses were not a positional nystagmus. Model simulations qualitatively predict all components of these eccentric rotation and tilt responses. These simulations support the conclusion that the VOR during eccentric rotation may consist of two components: a linear VOR and a rotational VOR. The model predicts a slow phase downward, vertical, linear VOR during eccentric rotation even though there was never a change in the force aligned with monkey's spinal (Z) axis. The model also predicts the torsional components of the response that shift the rotation axis of the angular VOR toward alignment with gravito-inertial force.

  14. A Reevaluation of the Vestibulo-Ocular Reflex: New Ideas of its Purpose, Properties, Neural Substrate, and Disorders

    NASA Technical Reports Server (NTRS)

    Leigh, R. John; Brandt, Thomas

    1992-01-01

    Conventional views of the Vestibulo-Ocular Reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved-locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (less than 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

  15. Context-specific adaptation of the gain of the vestibulo-ocular reflex in humans.

    PubMed

    Shelhamer, M; Robinson, D A; Tan, H S

    1992-01-01

    Previous experiments show that altered visual feedback can change VOR gain. Such changes also presumably occur when eyeglasses are donned and doffed, or when bifocals are worn. In these cases, a nonvisual cue accompanies the required gain adjustment (frames on/off for eyeglasses, looking up/down for bifocals). We set out to show that a subject can establish two VOR gains, and to determine if one of the associated nonvisual cues alone is sufficient to subsequently determine which gain to employ. Each of three subjects sat in a rotating chair inside an OKN drum during 2 hours of sinusoidal rotation at 0.2 Hz, 30 degrees/s peak. For 10 minutes the chair and drum counterrotated , driving VOR gain toward 1.7, while subjects looked up 20 degrees. Chair and drum were then coupled for 10 minutes, driving gain toward zero, during which subjects looked down 20 degrees. This sequence was repeated for 2 hours. Immediately thereafter, VOR gains were measured while subjects looked alternately up and down, using 20 degrees to 40 degrees step rotations. A fixation target, presented before and after each step, provided accurate gain determination by measuring the size of the re-fixation saccade. Results show a consistent reduced VOR gain looking downward (average 6%) and increased gain looking upward (average 6%) and increased gain looking upward (average 8%). We conclude that humans can adjust their VOR gain dependent on a situational context; we speculate that this context can take many forms. PMID:1342386

  16. Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. II. Inertial detection of angular velocity

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1996-01-01

    1. The dynamic contribution of otolith signals to three-dimensional angular vestibuloocular reflex (VOR) was studied during off-vertical axis rotations in rhesus monkeys. In an attempt to separate response components to head velocity from those to head position relative to gravity during low-frequency sinusoidal oscillations, large oscillation amplitudes were chosen such that peak-to-peak head displacements exceeded 360 degrees. Because the waveforms of head position and velocity differed in shape and frequency content, the particular head position and angular velocity sensitivity of otolith-ocular responses could be independently assessed. 2. During both constant velocity rotation and low-frequency sinusoidal oscillations, the otolith system generated two different types of oculomotor responses: 1) modulation of three-dimensional eye position and/or eye velocity as a function of head position relative to gravity, as presented in the preceding paper, and 2) slow-phase eye velocity as a function of head angular velocity. These two types of otolith-ocular responses have been analyzed separately. In this paper we focus on the angular velocity responses of the otolith system. 3. During constant velocity off-vertical axis rotations, a steady-state nystagmus was elicited that was maintained throughout rotation. During low-frequency sinusoidal off-vertical axis oscillations, dynamic otolith stimulation resulted primarily in a reduction of phase leads that characterize low-frequency VOR during earth-vertical axis rotations. Both of these effects are the result of an internally generated head angular velocity signal of otolithic origin that is coupled through a low-pass filter to the VOR. No change in either VOR gain or phase was observed at stimulus frequencies larger than 0.1 Hz. 4. The dynamic otolith contribution to low-frequency angular VOR exhibited three-dimensional response characteristics with some quantitative differences in the different response components. For

  17. Experimental tests of a superposition hypothesis to explain the relationship between the vestibuloocular reflex and smooth pursuit during horizontal combined eye-head tracking in humans

    NASA Technical Reports Server (NTRS)

    Huebner, W. P.; Leigh, R. J.; Seidman, S. H.; Thomas, C. W.; Billian, C.; DiScenna, A. O.; Dell'Osso, L. F.

    1992-01-01

    1. We used a modeling approach to test the hypothesis that, in humans, the smooth pursuit (SP) system provides the primary signal for cancelling the vestibuloocular reflex (VOR) during combined eye-head tracking (CEHT) of a target moving smoothly in the horizontal plane. Separate models for SP and the VOR were developed. The optimal values of parameters of the two models were calculated using measured responses of four subjects to trials of SP and the visually enhanced VOR. After optimal parameter values were specified, each model generated waveforms that accurately reflected the subjects' responses to SP and vestibular stimuli. The models were then combined into a CEHT model wherein the final eye movement command signal was generated as the linear summation of the signals from the SP and VOR pathways. 2. The SP-VOR superposition hypothesis was tested using two types of CEHT stimuli, both of which involved passive rotation of subjects in a vestibular chair. The first stimulus consisted of a "chair brake" or sudden stop of the subject's head during CEHT; the visual target continued to move. The second stimulus consisted of a sudden change from the visually enhanced VOR to CEHT ("delayed target onset" paradigm); as the vestibular chair rotated past the angular position of the stationary visual stimulus, the latter started to move in synchrony with the chair. Data collected during experiments that employed these stimuli were compared quantitatively with predictions made by the CEHT model. 3. During CEHT, when the chair was suddenly and unexpectedly stopped, the eye promptly began to move in the orbit to track the moving target. Initially, gaze velocity did not completely match target velocity, however; this finally occurred approximately 100 ms after the brake onset. The model did predict the prompt onset of eye-in-orbit motion after the brake, but it did not predict that gaze velocity would initially be only approximately 70% of target velocity. One possible

  18. Human vestibuloocular reflex and its interactions with vision and fixation distance during linear and angular head movement.

    PubMed

    Paige, G D; Telford, L; Seidman, S H; Barnes, G R

    1998-11-01

    Human vestibuloocular reflex and its interactions with vision and fixation distance during linear and angular head movement. J. Neurophysiol. 80: 2391-2404, 1998. The vestibuloocular reflex (VOR) maintains visual image stability by generating eye movements that compensate for both angular (AVOR) and linear (LVOR) head movements, typically in concert with visual following mechanisms. The VORs are generally modulated by the "context" in which head movements are made. Three contextual influences on VOR performance were studied during passive head translations and rotations over a range of frequencies (0.5-4 Hz) that emphasized shifting dynamics in the VORs and visual following, primarily smooth pursuit. First, the dynamic characteristics of head movements themselves ("stimulus context") influence the VORs. Both the AVOR and LVOR operate with high-pass characteristics relative to a head velocity input, although the cutoff frequency of the AVOR (<0.1 Hz) is far below that of the LVOR ( approximately 1 Hz), and both perform well at high frequencies that exceed, but complement, the capabilities of smooth pursuit. Second, the LVOR and AVOR are modulated by fixation distance, implemented with a signal related to binocular vergence angle ("fixation context"). The effect was quantified by analyzing the response during each trial as a linear relationship between LVOR sensitivity (in deg/cm), or AVOR gain, and vergence (in m-1) to yield a slope (vergence influence) and an intercept (response at 0 vergence). Fixation distance (vergence) was modulated by presenting targets at different distances. The response slope rises with increasing frequency, but much more so for the LVOR than the AVOR, and reflects a positive relationship for all but the lowest stimulus frequencies in the AVOR. A third influence is the context of real and imagined targets on the VORs ("visual context"). This was studied in two ways-when targets were either earth-fixed to allow visual enhancement of the VOR

  19. Three-dimensional ocular kinematics during eccentric rotations: evidence for functional rather than mechanical constraints

    NASA Technical Reports Server (NTRS)

    Angelaki, Dora E.

    2003-01-01

    Previous studies have reported that the translational vestibuloocular reflex (TVOR) follows a three-dimensional (3D) kinematic behavior that is more similar to visually guided eye movements, like pursuit, rather than the rotational VOR (RVOR). Accordingly, TVOR rotation axes tilted with eye position toward an eye-fixed reference frame rather than staying relatively fixed in the head like in the RVOR. This difference arises because, contrary to the RVOR where peripheral image stability is functionally important, the TVOR like pursuit and saccades cares to stabilize images on the fovea. During most natural head and body movements, both VORs are simultaneously activated. In the present study, we have investigated in rhesus monkeys the 3D kinematics of the combined VOR during yaw rotation about eccentric axes. The experiments were motivated by and quantitatively compared with the predictions of two distinct hypotheses. According to the first (fixed-rule) hypothesis, an eye-position-dependent torsion is computed downstream of a site for RVOR/TVOR convergence, and the combined VOR axis would tilt through an angle that is proportional to gaze angle and independent of the relative RVOR/TVOR contributions to the total eye movement. This hypothesis would be consistent with the recently postulated mechanical constraints imposed by extraocular muscle pulleys. According to the second (image-stabilization) hypothesis, an eye-position-dependent torsion is computed separately for the RVOR and the TVOR components, implying a processing that takes place upstream of a site for RVOR/TVOR convergence. The latter hypothesis is based on the functional requirement that the 3D kinematics of the combined VOR should be governed by the need to keep images stable on the fovea with slip on the peripheral retina being dependent on the different functional goals of the two VORs. In contrast to the fixed-rule hypothesis, the data demonstrated a variable eye-position-dependent torsion for the

  20. Adaptation of the macular vestibuloocular reflex to altered gravitational conditions in a fish ( Oreochromis mossambicus)

    NASA Astrophysics Data System (ADS)

    Horn, E.; Sebastian, C.

    Young fish ( Oreochromis mossambicus) were exposed to microgravity (μg) for 9 to 10 days, or to hypergravity (hg) for 9 days. For several weeks after termination of μg and hg, the roll-induced static vestibuloocular reflex (rVOR) was recorded. In stage 11/12-fish, the rVOR amplitude (angle between the maximal up and down movement of an eye during a complete 360° lateral roll) of μg-animals increased significantly by 25% compared to 1g-controls during the first post-flight week but decreased to the control level during the second post-flight week. Microgravity had no effect in stage 14/16 fish on the rVOR amplitude. After 3g-exposure, the rVOR amplitude was significantly reduced for both groups compared to their 1g-controls. Readaptation to 1g-condition was completed during the second post-3g week. We postulate a critical period during which the development of the macular vestibuloocular reflex depends on gravitational input, and which is limited by the first appearence of the rVOR. At this period of early development, exposure to microgravity sensitizes the vestibular system while hypergravity desensitizes it.

  1. Influence of stimulus interval on the habituation of vestibulo-ocular reflex and sensation of rotation in humans.

    PubMed

    Clément, Gilles; Tilikete, Caroline; Courjon, Jean-Hubert

    2013-08-01

    Previous studies in cats revealed that vestibular habituation of the vestibulo-ocular reflex (VOR) only occurs when velocity steps are delivered during the secondary phase nystagmus, suggesting that the presence of anti-compensatory slow phases may trigger the habituation process. We verified this property in humans by comparing vestibular habituation of VOR and sensation of rotation when steps were delivered either immediately after the perception of self-rotation had stopped, which is shortly before the nystagmus reverses direction; or when steps were delivered 60s later, i.e. during the secondary phase. Vestibular habituation of the VOR occurred in both instances. However, the decrease in VOR peak slow phase velocity and time constant was larger when steps were delivered after nystagmus reversal compared to before nystagmus reversal. The duration of the perception of self-rotation habituated equally for both conditions. These results confirm that VOR habituation fully develops only when velocity steps are delivered after the primary phase nystagmus. This finding may be helpful for minimizing the impact of repetitive vestibular stimuli in protocols using crossover design for drug studies, testing recovery in vestibular patients, or training people for different gravitoinertial environments. PMID:23827218

  2. 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.

  3. Generalized Hamiltonian point vortex dynamics on arbitrary domains using the method of fundamental solutions

    NASA Astrophysics Data System (ADS)

    Ashbee, T. L.; Esler, J. G.; McDonald, N. R.

    2013-08-01

    A new algorithm (VOR-MFS) is presented for the solution of a generalized Hamiltonian model of point vortex dynamics in an arbitrary two-dimensional computational domain. The VOR-MFS algorithm utilizes the method of fundamental solutions (MFS) to obtain an approximation to the model Hamiltonian by solution of an appropriate boundary value problem. Unlike standard point vortex methods, VOR-MFS requires knowledge only of the free-space (R2) Green's function for the problem as opposed to the domain-adapted Green's function, permitting solution of a much wider range of problems. VOR-MFS is first validated against a vortex image model for the case of (2D Euler) multiple vortex motion in both circular and 'Neumann-oval' shaped domains. It is then demonstrated that VOR-MFS can solve for quasi-geostrophic shallow water point vortex motion in the same domains. The exponential convergence of the MFS method is shown to lead to good conservation properties for each of the solutions presented.

  4. Integument und Anhangsorgane

    NASA Astrophysics Data System (ADS)

    Schliemann, Harald

    Das Integument umhüllt den Wirbeltierkörper lückenlos. In der embryonalen Mundbucht (Stomodaeum) und der Afterbucht (Proctodaeum) grenzt es an die Auskleidung des Darmrohres. Über die generelle Bedeutung einer Haut als Abgrenzung zwischen Körperinnenraum und Außenmedium hinaus hat es bei Schädeltieren ein breites Spektrum von Funktionen. Die wichtigsten sind: Mechanischer Schutz durch Verhornungen und Verknöch erungen; Wundheilung; Schutz vor Wasserverlust; Schutz vor Infektionen durch bakterizide Drüsensekrete und immunkompetente Zellen; Schutz vor kurzwelliger Strahlung durch Pigmente; Schutz vor Überwärmung durch Schweißdrüsensekrete und Schutz vor Wärmeverlust durch Federn und Haare; Ausbildung lokomotorisch wichtiger Strukturen wie Federn, Flug- und Schwimmhäute, Krallen und Hufe; Redukt ion des Strömungswiderstandes durch Dämpfungshaut; Abgabe von Sekreten zur Ernährung (Milch); Ausbildung von Strukturen zu Nahrungserwerb und_-bearbeitung, z. B. Zähne, Barten;

  5. What is the minimal vestibular function required for compensation?

    NASA Technical Reports Server (NTRS)

    Black, F. O.; Wade, S. W.; Nashner, L. M.

    1996-01-01

    Living with an uncompensated, abnormal vestibular system requires oppressive modification of life style and often prevents return to work and activities of daily living. Patients with vestibular abnormalities were studied to determine the minimal residual vestibular function required to achieve compensation. Three groups of patients with (a) complete unilateral loss of vestibular function with normal horizontal canal-vestibulo-ocular (HCVOR) function in the opposite ear, (b) complete unilateral loss with abnormal HCVOR function in the opposite ear, and (c) bilateral reduction of vestibular function from aminoglycoside toxicity underwent vestibuloocular (VOR), optokinetic (OKN), visual-VOR (VVOR), and computerized dynamic posturography (CDP) tests before and after therapeutic procedures. Results suggest that a minimal VOR response amplitude must be present for compensation of VVOR function to occur. The roles of VOR and OKN phase shifts in vestibular compensation are more complicated and require further study. Compensation of vestibulospinal function does not necessarily accompany VOR or VVOR compensation. Ascending and descending vestibular compensatory mechanisms may involve different spatial sensory inputs. Results of these studies have important implications for the diagnosis and treatment of patients with vestibular disorders, including selection and monitoring of patients for therapeutic regimens such as vestibular nerve section and streptomycin therapy.

  6. Age-related changes in human vestibulo-ocular reflexes: Sinusoidal rotation and caloric tests

    NASA Technical Reports Server (NTRS)

    Peterka, R. J.; Black, F. O.; Schoenhoff, M. B.

    1989-01-01

    The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR dynamics, and to identify the distributions of parameters which describe VOR responses to caloric and to sinusoidal rotational stimuli in a putatively normal population. Caloric test parameters showed no consistent trend with age. Rotation test parameters showed declining response amplitude and slightly less compensatory response phase with increasing age. The magnitudes of these changes were not large relative to the variability within the population. The age-related trends in VOR were not consistent with the anatomic changes in the periphery reported by others which showed an increasing rate of peripheral hair cell and nerve fiber loss in subjects over 55 years. The poor correlation between physiological and anatomical data suggest that adaptive mechanisms in the central nervous system are important in maintaining the VOR.

  7. The Vestibulo-ocular Reflex During Active Head Motion in Chiari II Malformation

    PubMed Central

    Salman, Michael S.; Sharpe, James A.; Lillakas, Linda; Dennis, Maureen; Steinbach, Martin J.

    2008-01-01

    Background Chiari type II malformation (CII) is a developmental anomaly of the cerebellum and brainstem, which are important structures for processing the vestibulo-ocular reflex (VOR). We investigated the effects of the deformity of CII on the angular VOR during active head motion. Methods Eye and head movements were recorded using an infrared eye tracker and magnetic head tracker in 20 participants with CII [11 males, age range 8-19 years, mean (SD) 14.4 (3.2) years]. Thirty-eight age-matched healthy children and adolescents (21 males) constituted the control group. Participants were instructed to ‘look’ in darkness at the position of their thumb, placed 25 cm away, while they made horizontal and vertical sinusoidal head rotations at frequencies of about 0.5 Hz and 2 Hz. Parametric and non-parametric tests were used to compare the two groups. Results The VOR gains, the ratio of eye to head velocities, were abnormally low in two participants with CII and abnormally high in one participant with CII. Conclusion The majority of participants with CII had normal VOR performance in this investigation. However, the deformity of CII can impair the active angular VOR in some patients with CII. Low gain is attributed to brainstem damage and high gain to cerebellar dysfunction. PMID:18973069

  8. Note: high frequency vibration rejection using a linear shaft actuator-based image stabilizing device via vestibulo-ocular reflex adaptation control method.

    PubMed

    Koh, Doo-Yeol; Kim, Young-Kook; Kim, Kyung-Soo; Kim, Soohyun

    2013-08-01

    In mobile robotics, obtaining stable image of a mounted camera is crucial for operating a mobile system to complete given tasks. This note presents the development of a high-speed image stabilizing device using linear shaft actuator, and a new image stabilization method inspired by human gaze stabilization process known as vestibulo-ocular reflex (VOR). In the proposed control, the reference is adaptively adjusted by the VOR adaptation control to reject residual vibration of a camera as the VOR gain converges to optimal state. Through experiments on a pneumatic vibrator, it will be shown that the proposed system is capable of stabilizing 10 Hz platform vibration, which shows potential applicability of the device to a high-speed mobile robot. PMID:24007125

  9. Note: High frequency vibration rejection using a linear shaft actuator-based image stabilizing device via vestibulo-ocular reflex adaptation control method

    NASA Astrophysics Data System (ADS)

    Koh, Doo-Yeol; Kim, Young-Kook; Kim, Kyung-Soo; Kim, Soohyun

    2013-08-01

    In mobile robotics, obtaining stable image of a mounted camera is crucial for operating a mobile system to complete given tasks. This note presents the development of a high-speed image stabilizing device using linear shaft actuator, and a new image stabilization method inspired by human gaze stabilization process known as vestibulo-ocular reflex (VOR). In the proposed control, the reference is adaptively adjusted by the VOR adaptation control to reject residual vibration of a camera as the VOR gain converges to optimal state. Through experiments on a pneumatic vibrator, it will be shown that the proposed system is capable of stabilizing 10 Hz platform vibration, which shows potential applicability of the device to a high-speed mobile robot.

  10. High-fidelity pulse density modulation in neuromorphic electric circuits utilizing natural heterogeneity

    NASA Astrophysics Data System (ADS)

    Utagawa, Akira; Asai, Tetsuya; Amemiya, Yoshihito

    Hospedales et al. have recently proposed a neural network model of the “vestibulo-ocular reflex” (VOR) in which a common input was given to multiple nonidentical spiking neurons that were exposed to uncorrelated temporal noise, and the output was represented by the sum of these neurons. Although the function of the VOR network is equivalent to pulse density modulation, the neurons' non-uniformity and temporal noises given to the neurons were shown to improve the output spike's fidelity to the analog input. In this paper, we propose a CMOS analog circuit for implementing the VOR network that exploits the non-uniformity of real MOS devices. Through extensive laboratory experiments using discrete MOS devices, we show that the output's fidelity to the input pulses is clearly improved by using multiple neuron circuits, in which the non-uniformity is naturally embedded into the devices.

  11. Herausforderungen für künftige Lernumgebungen am Beispiel der Fakultät für Medizin

    NASA Astrophysics Data System (ADS)

    Gergintchev, Ivan; Graf, Stephan

    Nach der weit reichenden Etablierung von eLearning in den letzten Jahren stehen nahezu alle deutschen Hochschulen vor der Aufgabe, wettbewerbsfähige hochschulübergreifende Mechanismen sowie entsprechende organisatorische Rahmenbedingungen zu schaffen. Vor allem die Umsetzung von EBologna und die Unterstützung kooperativer Bildungsangebote verstärken diese Notwendigkeit. Motiviert durch die Veränderungen im Bereich der Hochschullehre und die Herausforderungen für künftige Lernumgebungen schlagen wir eine Integrationslösung im Sinne eines Learning Gateway vor, die zur webgestützten Abwicklung von kooperativen Bildungsangeboten in heterogen Lernumgebungen eingesetzt werden kann. Ihre Praxisanwendung verdeutlichen wir anschließend im komplexen Szenario der Medizin an der TUM. Die Evaluierung der Umsetzung belegt den deutlichen Mehrwert des Ansatzes.

  12. Voluntary presetting of the vestibular ocular reflex permits gaze stabilization despite perturbation of fast head movements

    NASA Technical Reports Server (NTRS)

    Zangemeister, Wolfgang H.

    1989-01-01

    Normal subjects are able to change voluntarily and continuously their head-eye latency together with their compensatory eye movement gain. A continuous spectrum of intent-latency modes of the subject's coordinated gaze through verbal feedback could be demonstrated. It was also demonstrated that the intent to counteract any perturbation of head-eye movement, i.e., the mental set, permitted the subjects to manipulate consciously their vestibular ocular reflex (VOR) gain. From the data, it is inferred that the VOR is always on. It may be, however, variably suppressed by higher cortical control. With appropriate training, head-mounted displays should permit an easy VOR presetting that leads to image stabilization, perhaps together with a decrease of possible misjudgements.

  13. Comparison of smooth pursuit and combined eye-head tracking in human subjects with deficient labyrinthine function

    NASA Technical Reports Server (NTRS)

    Leigh, R. J.; Thurston, S. E.; Sharpe, J. A.; Ranalli, P. J.; Hamid, M. A.

    1987-01-01

    The effects of deficient labyrinthine function on smooth visual tracking with the eyes and head were investigated, using ten patients with bilateral peripheral vestibular disease and ten normal controls. Active, combined eye-head tracking (EHT) was significantly better in patients than smooth pursuit with the eyes alone, whereas normal subjects pursued equally well in both cases. Compensatory eye movements during active head rotation in darkness were always less in patients than in normal subjects. These data were used to examine current hypotheses that postulate central cancellation of the vestibulo-ocular reflex (VOR) during EHT. A model that proposes summation of an integral smooth pursuit command and VOR/compensatory eye movements is consistent with the findings. Observation of passive EHT (visual fixation of a head-fixed target during en bloc rotation) appears to indicate that in this mode parametric gain changes contribute to modulation of the VOR.

  14. Eye and head motion during head turns in spaceflight

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Uri, John J.; Moore, Thomas P.; Pool, Sam L.

    1988-01-01

    Eye-head motion was studied pre-, in- and postflight during single voluntary head turns. A transient increase in vestibulo-ocular reflex (VOR) gain occurred early in the flight, but later trended toward normal. This increased gain was produced by a relative increase in eye counterrotation velocity. Asymmetries in gain with right and left turns also occurred, caused by asymmetries in eye counterrotation velocities. These findings were remarkably similar to those from Soviet primate studies using gaze fixation targets, except the human study trended more rapidly toward normal. These findings differ substantially from those measuring VOR gain by head oscillation, in which no significant changes were found inflight. No visual disturbances were noted in either test condition or in normal activities. These head turn studies are the only ones to date documenting any functional change in VOR in weightlessness.

  15. Density and success of bird nests relative to grazing on western Montana grasslands

    USGS Publications Warehouse

    Fondell, T.F.; Ball, I.J.

    2004-01-01

    Grassland birds are declining at a faster rate than any other group of North American bird species. Livestock grazing is the primary economic use of grasslands in the western United States, but the effects of this use on distribution and productivity of grassland birds are unclear. We examined nest density and success of ground-nesting birds on grazed and ungrazed grasslands in western Montana. In comparison to grazed plots, ungrazed plots had reduced forb cover, increased litter cover, increased litter depth, and increased visual obstruction readings (VOR) of vegetation. Nest density among 10 of 11 common bird species was most strongly correlated with VOR of plots, and greatest nest density for each species occured where mean VOR of the plot was similar to mean VOR at nests. Additionally, all bird species were relatively consistent in their choice of VOR at nests despite substantial differences in VOR among plots. We suggest that birds selected plots based in part on availability of suitable nest sites and that variation in nest density relative to grazing reflected the effect of grazing on availability of nest sites. Nest success was similar between grazed plots and ungrazed plots for two species but was lower for nests on grazed plots than on ungrazed plots for two other species because of increased rates of predation, trampling, or parasitism by brown-headed cowbirds (Molothrus ater). Other species nested almost exclusively on ungrazed plots (six species) or grazed plots (one species), precluding evaluation of the effects of grazing on nest success. We demonstrate that each species in a diverse suite of ground-nesting birds preferentially used certain habitats for nesting and that grazing altered availability of preferred nesting habitats through changes in vegetation structure and plant species composition. We also show that grazing directly or indirectly predisposed some bird species to increased nesting mortality. Management alternatives that avoid intensive

  16. Prolonged vestibular stimulation induces homeostatic plasticity of the vestibulo-ocular reflex in larval Xenopus laevis.

    PubMed

    Dietrich, Haike; Straka, Hans

    2016-07-01

    Vestibulo-ocular reflexes (VOR) stabilise retinal images during head/body motion in vertebrates by generating spatio-temporally precise extraocular motor commands for corrective eye movements. While VOR performance is generally robust with a relatively stable gain, cerebellar circuits are capable of adapting the underlying sensory-motor transformation. Here, we studied cerebellum-dependent VOR plasticity by recording head motion-induced lateral rectus and superior oblique extraocular motor discharge in semi-intact preparations of Xenopus laevis tadpoles. In the absence of visual feedback, prolonged sinusoidal rotation caused either an increase or decrease of the VOR gain depending on the motion stimulus amplitude. The observed changes in extraocular motor discharge gradually saturated after 20 min of constant rotation and returned to baseline in the absence of motion stimulation. Furthermore, plastic changes in lateral rectus and superior oblique motor commands were plane-specific for horizontal and vertical rotations, respectively, suggesting that alterations are restricted to principal VOR connections. Comparison of multi- and single-unit activity indicated that plasticity occurs in all recorded units of a given extraocular motor nucleus. Ablation of the cerebellum abolished motoneuronal gain changes and prevented the induction of plasticity, thus demonstrating that both acquisition and retention of this type of plasticity require an intact cerebellar circuitry. In conclusion, the plane-specific and stimulus intensity-dependent modification of the VOR gain through the feed-forward cerebellar circuitry represents a homeostatic plasticity that likely maintains an optimal working range for the underlying sensory-motor transformation. PMID:27152983

  17. Vestibulo-ocular reflex gain as a measure of vestibular function in guinea pigs while in a recompression chamber: apparatus design and effects of nitrogen narcosis.

    PubMed

    Stevens, D M; Dutka, A J; Snyder, J E

    1995-05-01

    There are several mechanisms whereby alteration of barometric pressure can produce vertigo in divers or aviators. Development of a reliable measure of vestibular function in an animal model is the first requirement for further study of these mechanisms. This report presents the development of a rotatory table device capable of evoking the vestibulo-ocular reflex (VOR) of a guinea pig while in a hyperbaric chamber. To assess the reproducibility of this response, eight animals were monitored by electronystagmography during rotations at three table velocities (62.4, 83.3, and 100 degrees/s). Two test sessions were performed on each animal with a 6-hour interval between sessions. The VOR gain was calculated by dividing the average peak velocity of the slow phase component of the nystagmus by the peak stimulus velocity. At least eight observations per test speed were averaged; calibration of eye movement was performed prior to each session by forced ocular abduction. Multifactorial analysis of variance revealed no significant differences (p > .05) between the differing rotation speeds nor between test sessions for individual animals. However, there was a significant difference in VOR gain between animals (p < .002). The VOR gain was then measured, using the same techniques, in another group of seven animals before, during, and after an air dive to the equivalent of 200 feet of seawater (7.06 atmospheres absolute) to assess the effects of nitrogen narcosis. Pre- and post-dive VOR gains were significantly greater than those measured at depth (p < .05). These results are consistent with the slow processing model of nitrogen narcosis and the controversial theory that central nervous system depressants decrease the VOR gain. The results also demonstrate the ability of this inexpensive apparatus to provide a sensitive measure of pressure-induced changes of vestibular function in guinea pigs. PMID:8588631

  18. The mammalian efferent vestibular system plays a crucial role in the high-frequency response and short-term adaptation of the vestibuloocular reflex.

    PubMed

    Hübner, Patrick P; Khan, Serajul I; Migliaccio, Americo A

    2015-12-01

    Although anatomically well described, the functional role of the mammalian efferent vestibular system (EVS) remains unclear. Unlike in fish and reptiles, the mammalian EVS does not seem to play a role in modulation of primary afferent activity in anticipation of active head movements. However, it could play a role in modulating long-term mechanisms requiring plasticity such as vestibular adaptation. We measured the efficacy of vestibuloocular reflex (VOR) adaptation in α9-knockout mice. These mice carry a missense mutation of the gene encoding the α9 nicotinic acetylcholine receptor (nAChR) subunit. The α9 nAChR subunit is expressed in the vestibular and auditory periphery, and its loss of function could compromise peripheral input from the predominantly cholinergic EVS. We measured the VOR gain (eye velocity/head velocity) in 26 α9-knockout mice and 27 cba129 control mice. Mice were randomly assigned to one of three groups: gain-increase adaptation (1.5×), gain-decrease adaptation (0.5×), or no adaptation (baseline, 1×). After adaptation training (horizontal rotations at 0.5 Hz with peak velocity 20°/s), we measured the sinusoidal (0.2-10 Hz, 20-100°/s) and transient (1,500-6,000°/s(2)) VOR in complete darkness. α9-Knockout mice had significantly lower baseline gains compared with control mice. This difference increased with stimulus frequency (∼ 5% <1 Hz to ∼ 25% >1 Hz). Moreover, vestibular adaptation (difference in VOR gain of gain-increase and gain-decrease adaptation groups as % of gain increase) was significantly reduced in α9-knockout mice (17%) compared with control mice (53%), a reduction of ∼ 70%. Our results show that the loss of α9 nAChRs moderately affects the VOR but severely affects VOR adaptation, suggesting that the EVS plays a crucial role in vestibular plasticity. PMID:26424577

  19. Modification of the Passive Vestibulo-Ocular Reflex During and After Short-Duration Spaceflight

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Reschke, M. F.

    2011-01-01

    The vestibulo-ocular reflex (VOR) is mediated by integration of canal and otolith inputs to generate compensatory eye movements during head movements. We hypothesized that adaptive change in vestibular processing of gravitoinertial cues would be reflected by plane specific modification of the VOR during passive whole-body rotation during and after spaceflight. Using a repeated measures design, the VOR was assessed in four payload crewmembers in yaw, pitch and roll planes during multiple sessions before, during and after an 8 day orbital mission (STS-42). Rotation was about an earth-vertical axis during ground tests, with the head located off-axis by up to 45cm during pitch and roll rotation (peak acceleration less than 0.2g). The motion profiles included sum-of-sinusoids between 0.02 - 1.39 Hz (yaw), single sinusoids between 0.05-1.25 Hz (yaw and pitch) and velocity steps (yaw, pitch and roll). Eye movements were recorded with both video and electro-oculographic techniques. As expected, VOR gain changes were greater in pitch than in yaw. During pitch rotation, there was a progressive shift in the axis of eye movements during the flight, which was also present during the early post-flight period. This increased horizontal component during pitch, most prevalent at 0.2 Hz, was interpreted as an increase in a translational vergence response elicited during eccentric rotation as subjects imagined a wall fixed target. There was also an increased horizontal component during the eccentric roll step runs performed on flight day 7. These results are consistent with a frequency-dependent increase in otolith-mediated translational VOR responses following adaptation to microgravity. We conclude that the adaptive changes in the VOR are likely to be greatest in the frequency range where there is a cross-over of otolith-mediated tilt and translation responses.

  20. A reevaluation of the vestibulo-ocular reflex: new ideas of its purpose, properties, neural substrate, and disorders

    NASA Technical Reports Server (NTRS)

    Leigh, R. J.; Brandt, T.

    1993-01-01

    Conventional views of the vestibulo-ocular reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved--locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (< 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

  1. Herausforderungen durch die deutsche Wiedervereinigung

    NASA Astrophysics Data System (ADS)

    Stäglin, Reiner

    Die Wiedervereinigung stellte auch die Statistik vor große Aufgaben. Die als Organ der staatlichen Planung staatsnah orientierte Statistik der DDR musste auf das zur Neutralität und wissenschaftlichen Unabhängigkeit verpflichtete System der Bundesrepublik umgestellt werden. Ebenso verlangten die Universitäten eine Neuorientierung. Die Deutsche Statistische Gesellschaft hat sich vor allem dreier Aufgaben mit großem Engagement, aber auch mit Bedachtsamkeit angenommen: Aufnahme und Integration der Statistiker aus den neuen Bundesländern in die Gesellschaft, Begleitung der Neuausrichtung des Faches Statistik an deren Hochschulen und Sicherung sowie Nutzung von Datenbeständen der ehemaligen DDR.

  2. Kernschmelze Der nachhaltige Einfluss von Nuklearwaffen auf Politik und Wirtschaft

    NASA Astrophysics Data System (ADS)

    Greiner, Bernd

    "Was sollen wir von einer Kultur halten, der die Ethik stets als wesentliches Element des menschlichen Lebens galt, die aber - außer in fachlicher oder spieltheoretischer Terminologie - nicht in der Lage war, über die Möglichkeit zu sprechen, nahezu alle Menschen zu töten?" Der Fragesteller gehört zu den berühmtesten Physikern des 20. Jahrhunderts und zu den nach wie vor Umstrittensten. über ihn wurde in den 1960er Jahren ein international viel beachtetes Theaterstück geschrieben, vor wenigen Jahren gar eine Oper.

  3. Tantal

    NASA Astrophysics Data System (ADS)

    Dettner, H. W.; Franssen, H.; Giesen, K.; Hayes, E. T.; Holetzko, H.; Keysselitz, B.; Loebich, O.; Pelzel, E.; Reinsch, W.; Rostoker, W.; Saur, G.; Volk, K. E.; Wallbaum, H. J.; Borchers, Heinz; Schmidt, Ernst

    Tantal gehört zu den seltenen Metallen. In der Erdrinde kommt es in geringeren Mengen vor als Platin oder Uran. Die Welterzeugung an Tantal betrug 1957 etwa 400 t [K 2]. Tantal kommt in der Natur — wie das Schwestermetall Niob, mit dem es immer vergesellschaftet ist und von dem es nur sehr schwierig getrennt werden kann — fast ausschließlich in Form von Oxyden vor. Die wertvollsten Erze sind Tantalit (Eisen-Mangan-Tantalat mit 42...84% Ta2O5), Niob-Tantalit und Tantal-Niobit (25...40% Ta2O5).

  4. Einparksysteme

    NASA Astrophysics Data System (ADS)

    Knoll, Peter

    Bei nahezu allen Fahrzeugen ist die Sicht beim Rangieren stark eingeschränkt. Dies liegt vor allem an den modernen Fahrzeugkarosserien, mit denen möglichst niedrige Luftwiderstandsbeiwerte erreicht werden, um den Kraftstoffverbrauch zu reduzieren. In der Regel entsteht dadurch eine leichte Keilform. Vorhandene Hindernisse sind somit häufig nur schlecht oder überhaupt nicht erkennbar. So sieht der Durchschnittsfahrer beim Blick durch die Heckscheibe die Straßenoberfläche erst in einem Abstand von 8…10 m. Auch direkt vor dem Fahrzeug befindliche Hindernisse entziehen sich dem Blick des Fahrers, da sie durch den Fahrzeugvorbau verdeckt werden.

  5. A brief review of the clinical anatomy of the vestibular-ocular connections—how much do we know?

    PubMed Central

    Bronstein, A M; Patel, M; Arshad, Q

    2015-01-01

    The basic connectivity from the vestibular labyrinth to the eye muscles (vestibular ocular reflex, VOR) has been elucidated in the past decade, and we summarise this in graphic format. We also review the concept of ‘velocity storage', a brainstem integrator that prolongs vestibular responses. Finally, we present new discoveries of how complex visual stimuli, such as binocular rivalry, influence VOR processing. In contrast to the basic brainstem circuits, cortical vestibular circuits are far from being understood, but parietal-vestibular nuclei projections are likely to be involved. PMID:25412719

  6. 78 FR 11996 - Proposed Modification of Class D and Class E Airspace; Pueblo, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-21

    ...This action proposes to modify Class D airspace and the Class E airspace areas at Pueblo Memorial Airport, Pueblo, CO. Controlled airspace is necessary to accommodate aircraft using VHF Omni- Directional Radio Range/Distance Measuring Equipment (VOR/DME) standard instrument approach procedures at Pueblo Memorial Airport. The FAA is proposing this action to enhance the safety and management of......

  7. Vier Jahrhunderte Spannung

    NASA Astrophysics Data System (ADS)

    Loos, Andreas

    2000-06-01

    Im Jahre 1600 begründete William Gilbert die Elektrizitätslehre. Seitdem versuchten die Naturforscher dieses merkwürdige Phänomen zu ergründen und vor allem in Maschinen zu bändigen. Ein an Irrwegen und Gefahren reiches Zeitalter begann.

  8. Development and validation of reversed-phase column high-performance liquid chromatographic and first-derivative UV spectrophotometric methods for estimation of voriconazole in oral suspension powder.

    PubMed

    Prajapati, Arun M; Patel, Satish A; Patel, Natvarlal J; Patel, Dipti B; Patel, Sejal K

    2008-01-01

    This research paper describes validated reversed-phase high-performance column liquid chromatographic (RP-HPLC) and first-derivative UV spectrophotometric methods for the estimation of voriconazole (VOR) in oral suspension powder. The RP-HPLC separation was achieved on Phenomenex C18 column (250 x 4.6 mm id, 5 microm particle size) using water-acetonitrile (40 + 60, v/v; pH adjusted to 4.5 +/- 0.02 with acetic acid) as the mobile phase at a flow rate of 1.4 mL/min and ambient temperature. Quantification was achieved with photodiode array detection at 255 nm over the concentration range of 0.1-1 microg/mL with mean recovery of 99.49 +/- 0.83% for VOR by the RP-HPLC method. Quantification was achieved with UV detection at 266 nm over the concentration range of 8-20 microg/mL with mean recovery of 99.74 +/- 0.664% for VOR by the first-derivative UV spectrophotometric method. These methods are simple, precise, and sensitive, and they are applicable for the determination of VOR in oral suspension powder. PMID:18980120

  9. 14 CFR 171.13 - Reports.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Reports. 171.13 Section 171.13 Aeronautics... FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.13 Reports. The owner of each facility to which this subpart applies shall make the following reports on forms furnished by the FAA, at the...

  10. 78 FR 57472 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-19

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... Sec. 95.6002 VOR Federal Airway V2 Is Amended To Read in Part BADGER, WI VORTAC SUDDS, WI FIX 2900... BADGER, WI VORTAC MUSKEGON, MI VORTAC 56 BADGER. V216 Is Amended To Delete Changeover Point...

  11. 76 FR 11978 - Proposed Amendment of Federal Airways; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-04

    ...This action proposes to revise all Anchorage, AK, Federal airways that are affected by the relocation of the Anchorage VHF Omnidirectional Range (VOR) navigation aid. This action is necessary for the safety and management of Instrument Flight Rules (IFR) within the National Airspace...

  12. Werkstoffe

    NASA Astrophysics Data System (ADS)

    Pöhlandt, Klaus

    Für die Kaltmassivumformung eignen sich vor allem unlegierte und niedrig legierte Stähle. Tab. 3.1 zeigt eine Auswahl (eine ausführlichere Darstellung findet sich in VDI 3138-1). Der Kohlenstoffgehalt beträgt maximal etwa 0,5%. Die wichtigsten Legierungselemente sind Mn (<2%), Cr (<2%) sowie Ni, Mo und V.

  13. 78 FR 29613 - Modification and Revocation of Air Traffic Service Routes; Jackson, MS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-21

    ... airways; and cancel two VOR Federal airways in the vicinity of Jackson, MS (78 FR 10560, February 14, 2013... Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The...

  14. Learning in a Simple Motor System

    ERIC Educational Resources Information Center

    Broussard, Dianne M.; Kassardjian, Charles D.

    2004-01-01

    Motor learning is a very basic, essential form of learning that appears to share common mechanisms across different motor systems. We evaluate and compare a few conceptual models for learning in a relatively simple neural system, the vestibulo-ocular reflex (VOR) of vertebrates. We also compare the different animal models that have been used to…

  15. 78 FR 78794 - Proposed Establishment of Class E Airspace; Flagstaff, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-27

    ...This action proposes to establish Class E airspace at the Flagstaff VHF Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME) navigation aid, Flagstaff, AZ, to facilitate vectoring of Instrument Flight Rules (IFR) aircraft under control of Albuquerque Air Route Traffic Control Center (ARTCC). The FAA is proposing this action to enhance the safety and management of aircraft......

  16. 75 FR 65940 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ... Policies and Procedures (44 FR 11034; February 26,1979); and (3) does not warrant preparation of a... Intl, VOR RWY 3, Amdt 13 On September 15, 2010 (75 FR 178) the FAA published an Amendment in Docket No... 2010 Platinum, AK, Platinum, RNAV (GPS) RWY 14, Amdt 1 St. Paul Island, AK, St. Paul Island, ILS OR...

  17. Low-frequency otolith and semicircular canal interactions after canal inactivation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Merfeld, D. M.; Hess, B. J.

    2000-01-01

    During sustained constant velocity and low-frequency off-vertical axis rotations (OVAR), otolith signals contribute significantly to slow-phase eye velocity. The adaptive plasticity of these responses was investigated here after semicircular canal plugging. Inactivation of semicircular canals results in a highly compromised and deficient vestibulo-ocular reflex (VOR). Based on the VOR enhancement hypothesis, one could expect an adaptive increase of otolith-borne angular velocity signals due to combined otolith/canal inputs after inactivation of the semicircular canals. Contrary to expectations, however, the steady-state slow-phase velocity during constant velocity OVAR decreased in amplitude over time. A similar progressive decrease in VOR gain was also observed during low-frequency off-vertical axis oscillations. This response deterioration was present in animals with either lateral or vertical semicircular canals inactivated and was limited to the plane(s) of the plugged canals. The results are consistent with the idea that the low-frequency otolith signals do not simply enhance VOR responses. Rather, the nervous system appears to correlate vestibular sensory information from the otoliths and the semicircular canals to generate an integral response to head motion.

  18. 76 FR 30753 - Agency Information Collection Activities: Requests for Comments; Clearance of Renewed Approval of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-26

    ... collection requirement was published on August 12, 2008 (73 FR 46797). The collection of information is... CFR 91.161 in order to fly within 50 nautical miles (NM) of the Washington, DC omni-directional range... receive training and be tested for flying in the airspace that is within 60 NM of the DCA VOR/DME....

  19. 76 FR 45647 - Agency Information Collection Activities: Requests for Comments; Clearance of Renewed Approval of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-29

    ... requirement was published on August 12, 2008 (73 FR 46797). The collection of information is solicited by the... information is required of persons who must receive training and testing under 14 CFR 91.161 in order to fly... training and be tested for flying in the airspace that is within 60 NM of the DCA VOR/DME. This...

  20. Gating of neural error signals during motor learning

    PubMed Central

    Kimpo, Rhea R; Rinaldi, Jacob M; Kim, Christina K; Payne, Hannah L; Raymond, Jennifer L

    2014-01-01

    Cerebellar climbing fiber activity encodes performance errors during many motor learning tasks, but the role of these error signals in learning has been controversial. We compared two motor learning paradigms that elicited equally robust putative error signals in the same climbing fibers: learned increases and decreases in the gain of the vestibulo-ocular reflex (VOR). During VOR-increase training, climbing fiber activity on one trial predicted changes in cerebellar output on the next trial, and optogenetic activation of climbing fibers to mimic their encoding of performance errors was sufficient to implant a motor memory. In contrast, during VOR-decrease training, there was no trial-by-trial correlation between climbing fiber activity and changes in cerebellar output, and climbing fiber activation did not induce VOR-decrease learning. Our data suggest that the ability of climbing fibers to induce plasticity can be dynamically gated in vivo, even under conditions where climbing fibers are robustly activated by performance errors. DOI: http://dx.doi.org/10.7554/eLife.02076.001 PMID:24755290

  1. Studies of the vestibulo-ocular reflex on STS 4, 5 and 6

    NASA Technical Reports Server (NTRS)

    Thornton, William E.; Pool, Sam L.; Moore, Thomas P.; Uri, John J.

    1988-01-01

    The vestibulo-ocular reflex (VOR) may be altered by weightlessness. Since this reflex plays a large role in visual stabilization, it was important to document any changes caused by space flight. This is a report on findings on STS-4 through 6 and is part of a larger study of neurosensory adaptation done on STS-4 through 8. Voluntary horizontal head oscillations at 1/3 Hz with amplitude of 30 deg right and left of center were recorded by a potentiometer and compared to eye position recorded by electroculography under the following conditions: eyes open, head fixed, tracking horizontal targets switched 0, 15, and 30 degrees right and left (optokinetic reflex - OKR - and calibration); eyes open and fixed on static external target with oscillation, (vestibulo ocular reflex, eyes closed - VOR EC); eyes open and wearing opaque goggles with target fixed in imagination (vestibulo-ocular reflex, eyes shaded - VOR ES); and eyes open and fixed on a head synchronized target with head oscillation (VOR suppression). No significant changes were found in voluntary head oscillation frequency or amplitude in those with (n=5), and without (n=3), space motion sickness (SMS), with phase of flight or test condition. Variations in head oscillation were too small to have produced detectable changes in test results.

  2. 77 FR 27357 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-10

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... Route T255 Is Added To Read Marthas Vineyard, MA VOR/DME Falma, RI FIX 2000 17500 Falma, RI FIX... Minnk, RI FIX 2100 17500 Minnk, RI FIX Falma, RI FIX 1800 17500 Falma, RI FIX Marthas Vineyard, MA...

  3. 77 FR 50420 - Proposed Provision of Navigation Services for the Next Generation Air Transportation System...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-21

    ... published a Federal Register Notice (76 FR 77939) requesting comments on the FAA's plans for providing PBN... discontinuance of VOR navigation services. Comment #21: Comments from military and general aviation expressed... stakeholders, and the FAA will ] engage stakeholders in the discontinuance process. Comment #23: Military...

  4. 78 FR 75455 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-12

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26,1979); and (3) does...: Effective 9 January 2014 Little Rock, AR, Bill and Hillary Clinton National/Adams Field, RNAV (GPS) RWY 18..., Gatlinburg-Pigeon Forge, VOR/DME RWY 10, Amdt 6A Nacogdoches, TX, A L Mangham JR. Rgnl, ILS OR LOC RWY...

  5. [Activities of Psychology Dept., California Univ.

    NASA Technical Reports Server (NTRS)

    Bridgeman, Bruce

    1998-01-01

    We have completed two studies during the grant period, with manuscripts published or ready for submission for publication: (1) Dual adaptation and adaptive generalization in the human vestibuloocular reflex and (2) Frequency vs. acceleration specificity in human VOR adaptation. In the 1st study two studies examined the possibility that rotational VOR plasticity is subject to dual adaptation and adaptive generalization. Subjects in the experimental condition were exposed to an altered visual-vestibular environment for about four minutes every day for five consecutive days. The working hours between these testing sessions constituted re-exposure to the normal visual environment. Thus, subjects were repeatedly adapting and re-adapting to both environments which is a condition designed to produce dual adaptation. In each training session a measure of baseline VOR gain was obtained (in the dark). A small laser spot (the only visual stimulus) was systematically moved in the same direction as the subject's head, but by half the angle of rotation (target/head gain = 0.5). This resulted in adaptation values relativized to the non-adapted gain of each subject. These values were then analyzed using an analysis of variance with day and session (within a day) as factors. In the 2nd study human VOR adaption has been assumed to be frequency specific, despite the fact that the semicircular canals are simulated by rotational acceleration and not frequency per se.

  6. 78 FR 63861 - Modification of Class B Airspace; Minneapolis, MN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-25

    ... Class B airspace area (78 FR 10564). This action proposed to expand the lateral boundaries and lower... follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp... the Flying Cloud VOR/ DME navigation aid (FCM) 270 radial and the 20 NM to 30 NM arcs from the...

  7. 76 FR 6053 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-03

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... 34, Amdt 1 Richmond, VA, Richmond Intl, VOR RWY 2, Amdt 6 On January 10, 2011 (76 FR 06) the FAA..., RNAV (GPS) Z RWY 13, Amdt 1 Wadesboro, NC, Anson County-Jeff Cloud Field, ILS OR LOC RWY 34,...

  8. 76 FR 64005 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-17

    ... Policies and Procedures (44 FR 11034; February 26,1979); and (3) does not warrant preparation of a..., Takeoff Minimums and Obstacle DP, Orig, CANCELLED Lexington, MO, Lexington Muni, VOR/DME OR GPS RWY 22... County, Takeoff Minimums and Obstacle DP, Amdt 1 Maxton, NC, Laurinburg-Maxton, RNAV (GPS) RWY 5, Amdt...

  9. 77 FR 31180 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-25

    ... rule '' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26,1979); and (3) does not... 36, Orig Forest, VA, New London, Takeoff Minimums and Obstacle DP, Orig Effective 28 JUNE 2012 Arcata..., KY, Glasgow Muni, Takeoff Minimums and Obstacle DP, Amdt 1 Orange, MA, Orange Muni, VOR-A, Amdt...

  10. Vestibulo-Ocular Responses to Vertical Translation using a Hand-Operated Chair as a Field Measure of Otolith Function

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Campbell, D. J.; Reschke, M. F.; Prather, L.; Clement, G.

    2016-01-01

    The translational Vestibulo-Ocular Reflex (tVOR) is an important otolith-mediated response to stabilize gaze during natural locomotion. One goal of this study was to develop a measure of the tVOR using a simple hand-operated chair that provided passive vertical motion. Binocular eye movements were recorded with a tight-fitting video mask in ten healthy subjects. Vertical motion was provided by a modified spring-powered chair (swopper.com) at approximately 2 Hz (+/- 2 cm displacement) to approximate the head motion during walking. Linear acceleration was measured with wireless inertial sensors (Xsens) mounted on the head and torso. Eye movements were recorded while subjects viewed near (0.5m) and far (approximately 4m) targets, and then imagined these targets in darkness. Subjects also provided perceptual estimates of target distances. Consistent with the kinematic properties shown in previous studies, the tVOR gain was greater with near targets, and greater with vision than in darkness. We conclude that this portable chair system can provide a field measure of otolith-ocular function at frequencies sufficient to elicit a robust tVOR.

  11. 76 FR 72094 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-22

    ...; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February... From To MEA &95.6001 Victor Routes-U.S. &95.6014 VOR Federal Airway V14 is Amended to Read in Part...

  12. Reduction of ocular counter-rolling by adaptation to space

    NASA Technical Reports Server (NTRS)

    Dai, Mingjia; Mcgarvie, Leigh; Kozlovskaya, Inessa; Sirota, Mischa; Raphan, Theodore; Cohen, Bernard

    1993-01-01

    We studied the three-dimensional vestibulo-ocular reflex (VOR) of rhesus monkeys before and after the COSMOS Biosatellite 2229 Mission of 1992-1993. This included tests of ocular counter-rolling (OCR), the gain of the vestibulo-ocular reflex (VOR), and spatial orientation of velocity storage. A four-axis vestibular and oculomotor stimulator was transported to the Institute of Biomedical Problems in Moscow for the pre- and postflight ground-based testing. Twelve normal juvenile male rhesus monkey were implanted surgically with eye coils and tested 60-90 days before spaceflight. Two monkey (7906 and 6151), selected from the twelve as flight animals, flew from 12/29/92 to 1/10/93. Upon recovery, they were tested for 11 days postflight along with three control animals. Compensatory ocular torsion was produced in two ways: (1) Lateral head tilts evoked OCR through otolith-ocular reflexes. OCR was also measured dynamically during off-vertical axis rotation (OVAR). (2) Rotation about a naso-occipital axis that was either vertical of horizontal elicited torsional nystagmus through semicircular canal-ocular reflexes (roll VOR). OCR from the otoliths was substantially reduced (70 percent) for 11 days after reentry on both modes of testing. The gain of the roll VOR was also decreased, but less than OCR. These data demonstrate that there was a long-lasting depression of torsional or roll eye movements after adaptation to microgravity in these monkeys, especially those movements produced by the otolith organs.

  13. 75 FR 51663 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a..., MO, Rolla National, VOR/DME RNAV OR GPS RWY 22, Amdt 2C, CANCELLED St Joseph, MO, Rosecrans Memorial... Liberty Intl, ILS OR LOC RWY 11, Amdt 2 Newark, NJ, Newark Liberty Intl, ILS OR LOC RWY 22R, Amdt 5...

  14. Reversal of Motor Learning in the Vestibulo-Ocular Reflex in the Absence of Visual Input

    ERIC Educational Resources Information Center

    Cohen, Marlene R.; Meissner, Geoffrey W.; Schafer, Robert J.; Raymond, Jennifer L.

    2004-01-01

    Motor learning in the vestibulo-ocular reflex (VOR) and eyeblink conditioning use similar neural circuitry, and they may use similar cellular plasticity mechanisms. Classically conditioned eyeblink responses undergo extinction after prolonged exposure to the conditioned stimulus in the absence of the unconditioned stimulus. We investigated the…

  15. 78 FR 18266 - Proposed Establishment of Class E Airspace; Gillette, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR 71.1... Radio Range/Distance Measuring Equipment (VOR/DME), Gillette, WY to facilitate vectoring of...

  16. 77 FR 67782 - Proposed Amendment of Class E Airspace; Casper, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-14

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does....S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1...) traffic from en route airspace to the airport. Decommissioning of the Muddy Mountain VOR...

  17. 77 FR 23171 - Proposed Amendment of Class E Airspace; Fairfield, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 2. The incorporation by... proposed decommissioning of the Travis VHF Omni-Directional Radio Range (VOR) has made this...

  18. 77 FR 4708 - Proposed Amendment of Class E Airspace; Tobe, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 2. The incorporation by reference in 14 CFR.../Distance Measuring Equipment (VOR/DME). DATES: Comments must be received on or before March 16,...

  19. 76 FR 53361 - Proposed Revocation and Amendment of Class E Airspace; Olathe, KS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-26

    ... Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of... read as follows: Authority: 49 U.S.C. 106(g); 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959... Range/ Distance Measuring Equipment (VOR/DME) at Johnson County Executive Airport, Olathe, KS, has...

  20. 77 FR 35836 - Amendment of Air Traffic Service Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-15

    ... routes in the southwestern United States (78 FR 24156). An NPRM correction published in the Federal Register of May 23, 2012 (77 FR 30437) corrected the description of VOR Federal airway V-16. Interested... and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a...

  1. 78 FR 25404 - Proposed Establishment of Class E Airspace; Grand Canyon, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-01

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation... Range/Distance Measuring Equipment (VOR/DME) navigation aid, Grand Canyon, AZ, to facilitate...

  2. 77 FR 24156 - Proposed Amendment of Air Traffic Service Routes; Southwestern United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-23

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... continues to read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3... Route J-2, and VOR Federal airways V-16, V-66, and V-202 in southern Arizona and New Mexico. The FAA...

  3. 77 FR 23172 - Proposed Amendment of Class E Airspace; Woodland, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-18

    ... Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR...: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389... decommissioning of the Travis VHF Omni-Directional Radio Range (VOR) has made this action necessary for the...

  4. 78 FR 18928 - Proposed Amendment of Class E Airspace; Tuskegee, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-28

    ... Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a Regulatory Evaluation... read as follows: Authority: 49 U.S.C. 106(g); 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959... action proposes to amend Class E Airspace at Tuskegee, AL, as the Tuskegee VOR/DME has...

  5. Tipps und Tricks

    NASA Astrophysics Data System (ADS)

    Häger, Wolfgang; Bauermeister, Dirk

    Hier wollen wir einige uns nützlich erscheinende Hinweise zur Arbeit mit dem Inventor geben. Dabei geht es vor allem darum, das Arbeiten mit dem Inventor zu vereinfachen. Die Beispiele stellen eine unvollständige Aufzählung dar und sollen dazu anregen, nach alternativen Vorgehensweisen zu suchen (hier sei noch einmal ausdrücklich auf das Internet verwiesen).

  6. 78 FR 45475 - Proposed Establishment of Class E Airspace; Rome, OR

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-29

    ...; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation... Measuring Equipment (VOR/DME) navigation aid, Rome, OR, to facilitate vectoring of Instrument Flight...

  7. 78 FR 18264 - Proposed Establishment of Class E Airspace; Tobe, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR... U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71... Measuring Equipment (VOR/ DME), Tobe, CO to facilitate vectoring of Instrument Flight Rules (IFR)...

  8. 14 CFR 171.9 - Installation requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Installation requirements. 171.9 Section 171.9 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES VOR Facilities § 171.9 Installation requirements....

  9. 78 FR 40078 - Proposed Establishment of Class E Airspace; Cody, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-03

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR 71.1.../Distance Measuring Equipment (VOR/DME) navigation aid, Cody, WY, to facilitate vectoring of...

  10. 76 FR 78576 - Proposed Amendment of Class E Airspace; Hugo, CO

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-19

    ... 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 2. The incorporation by.../Distance Measuring Equipment (VOR/DME). This action also would make a minor adjustment to the...

  11. 75 FR 20321 - Proposed Amendment of Class E Airspace; Bozeman, MT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-19

    ... Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR... follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp... aircraft using a new VHF Omni-Directional Radio Range (VOR) Standard Instrument Approach Procedure...

  12. Automatic Classification of the Vestibulo-Ocular Reflex Nystagmus: Integration of Data Clustering and System Identification.

    PubMed

    Ranjbaran, Mina; Smith, Heather L H; Galiana, Henrietta L

    2016-04-01

    The vestibulo-ocular reflex (VOR) plays an important role in our daily activities by enabling us to fixate on objects during head movements. Modeling and identification of the VOR improves our insight into the system behavior and improves diagnosis of various disorders. However, the switching nature of eye movements (nystagmus), including the VOR, makes dynamic analysis challenging. The first step in such analysis is to segment data into its subsystem responses (here slow and fast segment intervals). Misclassification of segments results in biased analysis of the system of interest. Here, we develop a novel three-step algorithm to classify the VOR data into slow and fast intervals automatically. The proposed algorithm is initialized using a K-means clustering method. The initial classification is then refined using system identification approaches and prediction error statistics. The performance of the algorithm is evaluated on simulated and experimental data. It is shown that the new algorithm performance is much improved over the previous methods, in terms of higher specificity. PMID:26357393

  13. Visual Vestibular Interaction in the Dynamic Visual Acuity Test during Voluntary Head Rotation

    NASA Technical Reports Server (NTRS)

    Lee, Moo Hoon; Durnford, Simon; Crowley, John; Rupert, Angus

    1996-01-01

    Although intact vestibular function is essential in maintaining spatial orientation, no good screening tests of vestibular function are available to the aviation community. High frequency voluntary head rotation was selected as a vestibular stimulus to isolate the vestibulo-ocular reflex (VOR) from visual influence. A dynamic visual acuity test that incorporates voluntary head rotation was evaluated as a potential vestibular function screening tool. Twenty-seven normal subjects performed voluntary sinusoidal head rotation at frequencies from 0.7-4.0 Hz under three different visual conditions: visually-enhanced VOR, normal VOR, and visually suppressed VOR. Standardized Baily-Lovie chart letters were presented on a computer monitor in front of the subject, who then was asked to read the letters while rotating his head horizontally. The electro-oculogram and dynamic visual acuity score were recorded and analyzed. There were no significant differences in gain or phase shift among three visual conditions in the frequency range of 2.8 to 4.0 Hz. The dynamic visual acuity score shifted less than 0.3 logMAR at frequencies under 2.0 Hz. The dynamic visual acuity test at frequencies a round 2.0 Hz can be recommended for evaluating vestibular function.

  14. 78 FR 76784 - Proposed Modification, Revocation, and Establishment of Area Navigation (RNAV) Routes; Charlotte, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-19

    ... ``significant rule'' under Department of Transportation (DOT) Regulatory Policies and Procedures (44 FR 11034..., 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by.... The proposed routes, in combination with existing VOR Federal airways, would provide...

  15. 76 FR 65106 - Amendment of Federal Airways; Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... of effective date published in the Federal Register on June 16, 2011 (76 FR 35097). VOR Federal... No. FAA-2011-0010, Airspace Docket No. 11- AAL-1 published on April 28, 2011 (76 FR 23687), amends... subsequently delayed the effective date from June 30, 2011, until further notice (76 FR 35097; June 16,...

  16. 77 FR 42425 - Amendment of Air Traffic Service (ATS) Routes in the Vicinity of Vero Beach, FL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-19

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp...-79, and VHF omnidirectional range (VOR) ] Federal airways V-3, V-51, V-159, V-225, V-295 and...

  17. Molekularbiologische Speziesdifferenzierung

    NASA Astrophysics Data System (ADS)

    Mäde, Dietrich

    Der Speziesnachweis in Lebensmitteln dient der Analyse, aus welchen Tier- und Pflanzenarten die Erzeugnisse hergestellt wurden. Die Information darüber ist sowohl für den Gesundheitsschutz als auch für den Schutz vor Täuschungspraktiken und zur Information des Verbrauchers wichtig.

  18. Development of visual-display aid to air navigation

    NASA Technical Reports Server (NTRS)

    Matcovich, T. J.

    1973-01-01

    The developments are discussed in the design of a liquid-crystal, visual display, air navigation aid, which uses two VOR signals to locate the aircraft. The system concepts, liquid crystal materials, stability tests, and the electronic system are described. It is concluded that a navigational aid of this type is technically feasible, but not at the projected low cost.

  19. 77 FR 42627 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-20

    ... ``significant rule '' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26,1979); and (3) does..., Merritt Island, RNAV (GPS) RWY 11, Amdt 1A Orlando, FL, Orlando Kissimmee Gateway, VOR/DME-A, Amdt 1 Orlando, FL, Orlando Sanford Intl, ILS OR LOC RWY 27R, Amdt 2 Orlando, FL, Orlando Sanford Intl, RNAV...

  20. 76 FR 77939 - Proposed Provision of Navigation Services for the Next Generation Air Transportation System...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-15

    ...The Federal Aviation Administration (FAA) seeks comments on a proposed transition of the U.S. National Airspace System (NAS) navigation infrastructure to enable performance-based navigation (PBN) as part of the Next Generation Air Transportation System (NextGen). The FAA plans to transition from defining airways, routes and procedures using VHF Omni-directional Range (VOR) and other legacy......

  1. 78 FR 20783 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-08

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... DUPONT, DE VORTAC MODENA, PA VORTAC....... *3000 *1800--MOCA ] *2000--GNSS MEA Sec. 95.6068 VOR Federal...--MOCA **4000--GNSS MEA *WACCO, MO FIX *QUALM, MO FIX **3700 *3700--MRA **3000--MOCA QUALM, MO FIX...

  2. 78 FR 68699 - IFR Altitudes; Miscellaneous Amendments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-15

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... Part MC COMB, MS VORTAC *ROMAR, MS FIX **3000 *4000--MRA **1900--MOCA *ROMAR, MS FIX MAGNOLIA, MS VORTAC..... **3000 *4000--MRA **1900--MOCA Sec. 95.6018 VOR Federal Airway V18 is Amended to Read in...

  3. 75 FR 32096 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

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    ... Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of... 1A, CANCELLED Barrow, AK, Wiley Post-Will Rogers Memorial, VOR/DME RWY 25, Orig Muscle Shoals, AL, Northwest Alabama Rgnl, ILS OR LOC RWY 29, Amdt 5 Muscle Shoals, AL, Northwest Alabama Rgnl, RNAV (GPS)...

  4. 77 FR 71497 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

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    Federal Register 2010, 2011, 2012, 2013, 2014

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    Federal Register 2010, 2011, 2012, 2013, 2014

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  7. Neural processing of gravito-inertial cues in humans. I. Influence of the semicircular canals following post-rotatory tilt

    NASA Technical Reports Server (NTRS)

    Zupan, L. H.; Peterka, R. J.; Merfeld, D. M.; Peterson, B. W. (Principal Investigator)

    2000-01-01

    Sensory systems often provide ambiguous information. Integration of various sensory cues is required for the CNS to resolve sensory ambiguity and elicit appropriate responses. The vestibular system includes two types of sensors: the semicircular canals, which measure head rotation, and the otolith organs, which measure gravito-inertial force (GIF), the sum of gravitational force and inertial force due to linear acceleration. According to Einstein's equivalence principle, gravitational force is indistinguishable from inertial force due to linear acceleration. As a consequence, otolith measurements must be supplemented with other sensory information for the CNS to distinguish tilt from translation. The GIF resolution hypothesis states that the CNS estimates gravity and linear acceleration, so that the difference between estimates of gravity and linear acceleration matches the measured GIF. Both otolith and semicircular canal cues influence this estimation of gravity and linear acceleration. The GIF resolution hypothesis predicts that inaccurate estimates of both gravity and linear acceleration can occur due to central interactions of sensory cues. The existence of specific patterns of vestibuloocular reflexes (VOR) related to these inaccurate estimates can be used to test the GIF resolution hypothesis. To investigate this hypothesis, we measured eye movements during two different protocols. In one experiment, eight subjects were rotated at a constant velocity about an earth-vertical axis and then tilted 90 degrees in darkness to one of eight different evenly spaced final orientations, a so-called "dumping" protocol. Three speeds (200, 100, and 50 degrees /s) and two directions, clockwise (CW) and counterclockwise (CCW), of rotation were tested. In another experiment, four subjects were rotated at a constant velocity (200 degrees /s, CW and CCW) about an earth-horizontal axis and stopped in two different final orientations (nose-up and nose-down), a so

  8. The vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Young, L. R.

    1995-01-01

    The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in six male squirrel monkeys during eccentric rotation. Monkeys were rotated in the dark at a constant velocity of 200 degrees/s (centrally or 79 cm off axis) with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's orientation (facing-motion or back-to-motion) had a dramatic influence on the VOR. These experiments show that: (a) the axis of eye rotation always shifted toward alignment with gravito-inertial force; (b) the peak value of horizontal slow phase eye velocity was greater with the monkey facing-motion than with back-to-motion; and (c) the time constant of horizontal eye movement decay was smaller with the monkey facing-motion than with back-to-motion. All of these findings were statistically significant and consistent across monkeys. In another set of tests, the same monkeys were rapidly tilted about their naso-occipital (roll) axis. Tilted orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the angular rotation, no consistent eye velocity response was observed during or following the tilt for any of the six monkeys. The absence of any eye movement response following tilt weighs against the possibility that translational linear VOR responses are due to simple high-pass filtering of the otolith signals. The VOR response during eccentric rotation was divided into the more familiar angular VOR and linear VOR components. The angular component is known to depend upon semicircular canal dynamics and central influences. The linear component of the response decays rapidly with a mean duration of only 6.6 s, while the axis of eye rotation rapidly aligns (< 10 s) with gravito-inertial force. These

  9. Three dimensional kinematics of rapid compensatory eye movements in humans with unilateral vestibular deafferentation.

    PubMed

    Tian, Jun-Ru; Crane, Benjamin T; Ishiyama, Akira; Demer, Joseph L

    2007-09-01

    Saccades executed with the head stationary have kinematics conforming to Listing's law (LL), confining the ocular rotational axis to Listing's plane (LP). In unilateral vestibular deafferentation (UVD), the vestibulo-ocular reflex (VOR), which does not obey LL, has at high head acceleration a slow phase that has severely reduced velocity during ipsilesional rotation, and mildly reduced velocity during contralesional rotation. Studying four subjects with chronic UVD using 3D magnetic search coils, we investigated kinematics of stereotypic rapid eye movements that supplement the impaired VOR. We defined LP with the head immobile, and expressed eye and head movements as quaternions in LP coordinates. Subjects underwent transient whole body yaw at peak acceleration 2,800 degrees /s(2) while fixating targets centered, or 20 degrees up or down prior to rotation. The VOR shifted ocular torsion out of LP. Vestibular catch-up saccades (VCUS) occurred with mean latency 90 +/- 44 ms (SD) from ipsilesional rotation onset, maintained initial non-LL torsion so that their quaternion trajectories paralleled LP, and had velocity axes changing by half of eye position. During contralesional rotation, rapid eye movements occurred at mean latency 135 +/- 36 ms that were associated with abrupt decelerations (ADs) of the horizontal slow phase correcting 3D deviations in its velocity axis, with quaternion trajectories not paralleling LP. Rapid eye movements compensating for UVD have two distinct kinematics. VCUS have velocity axis dependence on eye position consistent with LL, so are probably programmed in 2D by neural circuits subserving visual saccades. ADs have kinematics that neither conform to LL nor match the VOR axis, but appear instead programmed in 3D to correct VOR axis errors. PMID:17549461

  10. Effects of 4-aminopyridine on nystagmus and vestibulo-ocular reflex in ataxia-telangiectasia.

    PubMed

    Shaikh, Aasef G; Marti, Sarah; Tarnutzer, Alexander A; Palla, Antonella; Crawford, Thomas O; Zee, David S; Straumann, Dominik

    2013-11-01

    Ataxia-telangiectasia (A-T) is a progressive neurodegenerative disorder with prominent eye movement deficits localizing to the cerebellum. We sought to determine if 4-aminopyridine (4-AP), which putatively enhances the precision of Purkinje neurons, could improve the disorders of eye movements and vestibular function in A-T. The influence of 4-AP on disorders of eye movements and vestibular function was studied in four A-T patients. The effects on the cerebellar control of vestibulo-ocular reflex (VOR) was quantitatively assessed by the decay time constant of per- and post-rotational nystagmus during constant velocity en bloc rotations. The length of the VOR time constant determines the fidelity of the vestibular velocity storage, a neural mechanism that increases the bandwidth of VOR under cerebellar control. The VOR time constant was not increased in A-T patients. The latter is explained by the extent of cerebellar lesion as previously described in A-T and other cerebellar disorders. Nevertheless, 4-AP shortened the VOR time constant during horizontal rotations. Severe disinhibition of velocity storage in subjects with putatively profound cerebellar degeneration manifest periodic alternating nystagmus (PAN). Among two A-T subjects who manifested PAN, 4-AP reduced the peak slow phase velocity of the more severely affected individual and abrogated the PAN in the other. Two A-T subjects manifested horizontal and vertical spontaneous nystagmus (SN) in primary gaze, 4-AP reduced its slow phase velocity. We conclude that in subjects with A-T 4-AP has a prominent effect on the ocular motor and vestibular deficits that are ascribed to the loss of cerebellar Purkinje neurons. PMID:23884713

  11. 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.

  12. Temporal dynamics of semicircular canal and otolith function following acute unilateral vestibular deafferentation in humans.

    PubMed

    Tian, Jun-ru; Ishiyama, Akira; Demer, Joseph L

    2007-04-01

    Dynamic changes of deficits in canal and otolith vestibulo-ocular reflexes (VORs) to high acceleration, eccentric yaw rotations were investigated in five subjects aged 25-65 years before and at frequent intervals 3-451 days following unilateral vestibular deafferentation (UVD) due to labyrinthectomy or vestibular neurectomy. Eye and head movements were recorded using magnetic search coils during transients of directionally random, whole-body rotation in darkness at peak acceleration 2,800 degrees/s2. Canal VORs were characterized during rotation about a mid-otolith axis, viewing a target 500 cm distant until rotation onset in darkness. Otolith VOR responses were characterized by the increase in VOR gain during identical rotation about an axis 13 cm posterior to the otoliths, initially viewing a target 15 cm distant. Pre-UVD canal gain was directionally symmetrical, averaging 0.87 +/- 0.02 (+/-SEM). Contralesional canal gain declined from pre-UVD by an average of 22% in the first 3-5 days post-UVD, before recovering to an asymptote of close 90% of pre-UVD level at 1-3 months. This recovery corresponded to resolution of spontaneous nystagmus. Ipsilesional gain declined to 59%, and showed no consistent recovery afterwards. Pre-UVD otolith gain was directionally symmetrical, averaging 0.56 +/- 0.02. Immediately after UVD, the contralesional otolith gain declined to 0.30 +/- 0.02, and did not recover. Ipsilesional otolith gain declined profoundly to 0.08 +/- 0.03 (P < 0.01), and never recovered. In contrast to the modest and directionally symmetrical effect of UVD on the human otolith VOR during pure translational acceleration, otolith gain during eccentric yaw rotation exhibited a profound and lasting deficit that might be diagnostically useful in lateralizing otolith pathology. Most recovery of the human canal gain to high acceleration transients following UVD is for contralesional head rotation, occurring within 3 months as spontaneous nystagmus resolves. PMID

  13. Combined autophagy and HDAC inhibition

    PubMed Central

    Mahalingam, Devalingam; Mita, Monica; Sarantopoulos, John; Wood, Leslie; Amaravadi, Ravi K; Davis, Lisa E; Mita, Alain C; Curiel, Tyler J; Espitia, Claudia M; Nawrocki, Steffan T; Giles, Francis J; Carew, Jennifer S

    2014-01-01

    We previously reported that inhibition of autophagy significantly augmented the anticancer activity of the histone deacetylase (HDAC) inhibitor vorinostat (VOR) through a cathepsin D-mediated mechanism. We thus conducted a first-in-human study to investigate the safety, preliminary efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and VOR in patients with advanced solid tumors. Of 27 patients treated in the study, 24 were considered fully evaluable for study assessments and toxicity. Patients were treated orally with escalating doses of HCQ daily (QD) (d 2 to 21 of a 21-d cycle) in combination with 400 mg VOR QD (d one to 21). Treatment-related adverse events (AE) included grade 1 to 2 nausea, diarrhea, fatigue, weight loss, anemia, and elevated creatinine. Grade 3 fatigue and/or myelosuppression were observed in a minority of patients. Fatigue and gastrointestinal AE were dose-limiting toxicities. Six-hundred milligrams HCQ and 400 mg VOR was established as the maximum tolerated dose and recommended phase II regimen. One patient with renal cell carcinoma had a confirmed durable partial response and 2 patients with colorectal cancer had prolonged stable disease. The addition of HCQ did not significantly impact the PK profile of VOR. Treatment-related increases in the expression of CDKN1A and CTSD were more pronounced in tumor biopsies than peripheral blood mononuclear cells. Based on the safety and preliminary efficacy of this combination, additional clinical studies are currently being planned to further investigate autophagy inhibition as a new approach to increase the efficacy of HDAC inhibitors. PMID:24991835

  14. The video head impulse test during post-rotatory nystagmus: physiology and clinical implications.

    PubMed

    Mantokoudis, Georgios; Tehrani, Ali S Saber; Xie, Li; Eibenberger, Karin; Eibenberger, Bernhard; Roberts, Dale; Newman-Toker, David E; Zee, David S

    2016-01-01

    The aim of this study was to test the effects of a sustained nystagmus on the head impulse response of the vestibulo-ocular reflex (VOR) in healthy subjects. VOR gain (slow-phase eye velocity/head velocity) was measured using video head impulse test goggles. Acting as a surrogate for a spontaneous nystagmus (SN), a post-rotatory nystagmus (PRN) was elicited after a sustained, constant-velocity rotation, and then head impulses were applied. 'Raw' VOR gain, uncorrected for PRN, in healthy subjects in response to head impulses with peak velocities in the range of 150°/s-250°/s was significantly increased (as reflected in an increase in the slope of the gain versus head velocity relationship) after inducing PRN with slow phases of nystagmus of high intensity (>30°/s) in the same but not in the opposite direction as the slow-phase response induced by the head impulses. The values of VOR gain themselves, however, remained in the normal range with slow-phase velocities of PRN < 30°/s. Finally, quick phases of PRN were suppressed during the first 20-160 ms of a head impulse; the time frame of suppression depended on the direction of PRN but not on the duration of the head impulse. Our results in normal subjects suggest that VOR gains measured using head impulses may have to be corrected for any superimposed SN when the slow-phase velocity of nystagmus is relatively high and the peak velocity of the head movements is relatively low. The suppression of quick phases during head impulses may help to improve steady fixation during rapid head movements. PMID:26449967

  15. Dynamic properties of the human vestibulo-ocular reflex during head rotations in roll

    NASA Technical Reports Server (NTRS)

    Seidman, S. H.; Leigh, R. J.; Tomsak, R. L.; Grant, M. P.; Dell'Osso, L. F.

    1995-01-01

    We investigated the dynamic properties of the human vestibulo-ocular reflex (VOR) during roll head rotations in three human subjects using the magnetic search coil technique. In the first of two experiments, we quantify the behavior of the ocular motor plant in the torsional plane. The subject's eye was mechanically displaced into intorsion, extorsion or abduction, and the dynamic course of return of the eye to its resting position was measured. The mean predominant time constants of return were 210 msec from intorsion, 83 msec from extorsion, and 217 msec from abduction, although there was considerable variability of results from different trials and subjects. In the second experiment, we quantify the efficacy of velocity-to-position integration of the vestibular signal. Position-step stimuli were used to test the torsional or horizontal VOR, being applied with subjects heads erect or supine. After a torsional position-step, the eye drifted back to its resting position, but after a horizontal position-step the eye held its new horizontal position. To interpret these responses we used a simple model of the VOR with parameters of the ocular motor plant set to values determined during Exp 1. The time constant of the velocity-to-position neural integrator was smaller (typically 2 sec) in the torsional plane than in the horizontal plane (> 20 sec). No disconjugacy of torsional eye movements was observed. Thus, the dynamic properties of the VOR in roll differ significantly from those of the VOR in yaw, reflecting different visual demands placed on this reflex in these two planes.

  16. Translational Vestibulo-Ocular Reflexes During Off-Vertical Axis Rotation

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Clement, Gilles

    2009-01-01

    The translational vestibulo-ocular reflex (tVOR) is an otolith-mediated response that stabilizes near vision during linear acceleration at higher frequencies where visually mediated reflexes are not adequate. The modulation of horizontal and vergence eye movements during Off-Vertical Axis Rotation (OVAR) are presumed to reflect the tVOR in response to the continuously varying linear acceleration in the interaural and nasooccipital axes, respectively. The purpose of this study was to examine the effect of frequency and fixation distance on the modulation of slow phase eye velocity (SPV) as further evidence that the tVOR is elicited during OVAR. Eighteen subjects were rotated about their longitudinal axis tilted by 30 deg off-vertical. Rotational velocities varied between 18 and 288 deg/sec corresponding to a frequency range of 0.05 to 0.8 Hz. Fixation distance was altered by asking subjects to imagine stationary targets that were briefly presented at 0.5, 1 and 2 m during some rotation cycles. The target flash was 40 msec in the nose-up position at eye level. Oculomotor responses were recorded in the dark using infrared binocular videography. Sinusoidal curve fits were used to derive amplitude, phase and bias velocity of the eye movements across multiple rotation cycles. Consistent with previous studies, the modulation of both horizontal and vergence SPV increased with stimulus frequency. The effect of fixation distance was negligible at lower frequencies. The modulation of horizontal and vergence SPV was; however, proportional to fixation distance during OVAR at 0.8 Hz. This increasing sensitivity and dependence on fixation distance of horizontal and vergence SPV during OVAR is consistent with tVOR characteristics measured during other types of linear motion. We conclude that the modulation of horizontal and vergence SPV will be diagnostically more useful at higher stimulus frequencies where the tVOR is more robust.

  17. Extreme vestibulo-ocular adaptation induced by prolonged optical reversal of vision

    PubMed Central

    Gonshor, A.; Jones, G. Melvill

    1976-01-01

    1. These experiments investigated plastic changes in the vestibulo-ocular reflex (VOR) of human subjects consequent to long-term optical reversal of vision during free head movement. Horizontal vision-reversal was produced by head-mounted dove prisms. Four normal adults were continuously exposed to these conditions during 2, 6, 7 and 27 days respectively. 2. A sinusoidal rotational stimulus, previously shown to be nonhabituating (1/6 Hz; 60°/sec amplitude), was used to test the VOR in the dark at frequent intervals both during the period of vision-reversal and an equal period after return to normal vision. D.c. electro-oculography (EOG) was used to record eye movement, taking care to avoid changes of EOG gain due to light/dark adaptation of the retina. 3. All subjects showed substantial reduction of VOR gain (eye velocity/head velocity) during the first 2 days of vision-reversal. The 6-, 7- and 27-day subjects showed further reduction of gain which reached a low plateau at about 25% the normal value by the end of one week. At this time the attenuation of some EOG records was so marked as to defy extraction of a meaningful sinusoidal signal. 4. After removal of the prisms VOR gain recovered along a time course which approximated that of the original adaptive attenuation. 5. In the 27-day experiment large changes of phase developed in the VOR during the second week of vision-reversal. These changes generally progressed in a lagging sense, to reach 130° phase lag relative to normal by the beginning of the third week. Accompanying this was a considerable restoration of gain from 25 to 50% the normal value. These adapted conditions, which approximate functional reversal of the reflex, were then maintained steady, even overnight, until return to normal vision on the 28th day. 6. Thereafter, whereas VOR phase returned to near-normal in 2 hr, restoration of gain occupied a further 2-3 weeks. 7. There was a highly systematic relation between instantaneous gain and phase

  18. 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

  19. Flexibility of vestibulo-ocular reflex adaptation to modified visual input in human.

    PubMed

    Watanabe, Shoji; Hattori, Kosuke; Koizuka, Izumi

    2003-02-01

    The vestibulo-ocular reflex (VOR) serves to keep images relatively stable on the retina. To maintain appropriate performance and minimize image slip throughout life, VOR is subjected to long-term adaptive regulation by visual input. It has been reported that adaptive changes in VOR gain (eye velocity/head velocity) are evoked either by fitting subjects with magnifying, miniaturizing, or reversing spectacles during normal behavior, or by moving a large visual field in or out of phase relative to the subject's head movement. The changes in VOR gain are frequency selective. Here, we examine the extent of VOR gain flexibility by causing VORs of similar direction to undergo different behavioral gain changes. Nine healthy adults participated in the study, ranging in age from 24 to 38 years (mean: 26 years) and with no history of neurotological symptoms. All subjects were clinically normal according to a screening battery that included combined neurologic and otologic physical examinations. Horizontal and vertical eye positions were recorded by bitemporal DC-coupled electro-oculography (EOG). The subject sat in a rotating chair. The axis of rotation of the body was always earth-vertical, with the interaural axis crossing the axis of rotation of the chair. The head was pointed 20 degrees downwards in all experiments and stabilized in this position using a chin rest. The chair was surrounded by a half-cylindrical optokinetic screen (78 cm in diameter) placed in front of the subject, onto which random dot patterns were projected. Goggles were used to ensure that the subject was in complete darkness during both pre- and postadaptation periods. The chair was rotated sinusoidally at maximum amplitude of 30 degrees or 60 degrees : for 30 degrees the stimulation was at 0.1, 0.2, 0.3, and 0.4 Hz; for 60 degrees it was at 0.1, 0.2, and 0.3 Hz. VOR adaptation was obtained by inducing a retinal slip velocity by short-term alteration of the visual input of the large field; this change

  20. Characterizing high-velocity angular vestibulo-ocular reflex function in service members post-blast exposure

    PubMed Central

    Scherer, Matthew R.; Shelhamer, Mark J.; Schubert, Michael C.

    2011-01-01

    Blasts (explosions) are the most common mechanism of injury in modern warfare. Traumatic brain injury (TBI) and dizziness are common sequelae associated with blasts, and many service members (SMs) report symptoms worsen with activity. The purpose of this study was to measure angular vestibulo-ocular reflex gain (aVOR) of blast-exposed SMs with TBI during head impulse testing. We also assessed their symptoms during exertion. Twenty-four SMs recovering from TBI were prospectively assigned to one of two groups based on the presence or absence of dizziness. Wireless monocular scleral search coil and rate sensor were used to characterize active and passive yaw and pitch head and eye rotations. Visual analog scale (VAS) was used to monitor symptoms during fast walking/running. For active yaw head impulses, aVOR gains were significantly lower in the symptomatic group (0.79 ± 0.15) versus asymptomatic (0.87 ± 0.18), but not for passive head rotation. For pitch head rotation, the symptomatic group had both active (0.915 ± 0.24) and passive (0.878 ± 0.22) aVOR gains lower than the asymptomatic group (active 1.03 ± 0.27, passive 0.97 ± 0.23). Some SMs had elevated aVOR gain. VAS scores for all symptoms were highest during exertion. Our data suggest symptomatic SMs with TBI as a result of blast have varied aVOR gain during high-velocity head impulses and provide compelling evidence of pathology affecting the vestibular system. Potential loci of injury in this population include the following: disruption of pathways relaying vestibular efference signals, differential destruction of type I vestibular hair cells, or selective damage to irregular afferent pathways—any of which may explain the common discrepancy between reports of vestibular-like symptoms and laboratory testing results. significantly reduced pitch aVOR in symptomatic SMs and peak symptom severity during exertional testing support earlier findings in the chronic blast-exposed active duty SMs. PMID:21113582

  1. Baclofen and velocity storage: a model of the effects of the drug on the vestibulo-ocular reflex in the rhesus monkey.

    PubMed Central

    Cohen, B; Helwig, D; Raphan, T

    1987-01-01

    1. Baclofen had a characteristic effect on vestibular and optokinetic nystagmus in rhesus monkeys. Each aspect of nystagmus that is dependent on the velocity-storage mechanism in the vestibulo-ocular reflex (v.o.r.) was altered by the drug: (a) Baclofen reduced the dominant time constant of the v.o.r. in a dose-dependent manner up to 5 mg/kg, the highest dosage used. The alteration in v.o.r. time constant began within 15 min of injection, was maximal between 1 and 4 h, and lasted for 14-18 h. This effect mirrors changes in plasma levels of baclofen after oral doses in humans (Faigle, Keberle & Agen, 1980). (b) Slow-phase velocities of steady-state nystagmus induced by rotation about axes tilted from the vertical (off-vertical axis rotation, o.v.a.r.) were reduced after baclofen and could not be maintained at previous levels. (c) There was a dose-dependent decline in the steady-state gain of optokinetic nystagmus (o.k.n.), and at the highest dosages little o.k.n. was induced. In parallel, the peak velocity and falling time constant of optokinetic after-nystagmus (o.k.a.n.) were reduced. Since baclofen is a GABA agonist, systems utilizing GABA and acting on GABAB receptors appear to produce inhibitory control of velocity storage. 2. The step gain of the v.o.r., measured at the beginning and end of constant-velocity rotation in darkness, was unaffected by baclofen, as were saccades, quick phases of nystagmus, and the ability to hold positions of fixation or to generate linear slow phases of nystagmus. This indicates that it is possible to use baclofen to manipulate the dominant time constant of the v.o.r. and of o.k.a.n. in relative isolation from effects on other oculomotor components. 3. Baclofen caused a dose-dependent reduction in the initial jump in eye velocity at the onset of o.k.n., suggesting that the initial jump is also under inhibitory control of GABAB receptors. However, there were still occasional slow phases with velocities up to 30-40 deg/s after

  2. Characterizing high-velocity angular vestibulo-ocular reflex function in service members post-blast exposure.

    PubMed

    Scherer, Matthew R; Shelhamer, Mark J; Schubert, Michael C

    2011-02-01

    Blasts (explosions) are the most common mechanism of injury in modern warfare. Traumatic brain injury (TBI) and dizziness are common sequelae associated with blasts, and many service members (SMs) report symptoms worsen with activity. The purpose of this study was to measure angular vestibulo-ocular reflex gain (aVOR) of blast-exposed SMs with TBI during head impulse testing. We also assessed their symptoms during exertion. Twenty-four SMs recovering from TBI were prospectively assigned to one of two groups based on the presence or absence of dizziness. Wireless monocular scleral search coil and rate sensor were used to characterize active and passive yaw and pitch head and eye rotations. Visual analog scale (VAS) was used to monitor symptoms during fast walking/running. For active yaw head impulses, aVOR gains were significantly lower in the symptomatic group (0.79 ± 0.15) versus asymptomatic (0.87 ± 0.18), but not for passive head rotation. For pitch head rotation, the symptomatic group had both active (0.915 ± 0.24) and passive (0.878 ± 0.22) aVOR gains lower than the asymptomatic group (active 1.03 ± 0.27, passive 0.97 ± 0.23). Some SMs had elevated aVOR gain. VAS scores for all symptoms were highest during exertion. Our data suggest symptomatic SMs with TBI as a result of blast have varied aVOR gain during high-velocity head impulses and provide compelling evidence of pathology affecting the vestibular system. Potential loci of injury in this population include the following: disruption of pathways relaying vestibular efference signals, differential destruction of type I vestibular hair cells, or selective damage to irregular afferent pathways-any of which may explain the common discrepancy between reports of vestibular-like symptoms and laboratory testing results. Significantly reduced pitch aVOR in symptomatic SMs and peak symptom severity during exertional testing support earlier findings in the chronic blast-exposed active duty SMs. PMID

  3. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. I. Normal responses

    NASA Technical Reports Server (NTRS)

    Minor, L. B.; Lasker, D. M.; Backous, D. D.; Hullar, T. E.; Shelhamer, M. J. (Principal Investigator)

    1999-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in five squirrel monkeys with intact vestibular function. The VOR evoked by steps of acceleration in darkness (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) began after a latency of 7.3 +/- 1.5 ms (mean +/- SD). Gain of the reflex during the acceleration was 14.2 +/- 5.2% greater than that measured once the plateau head velocity had been reached. A polynomial regression was used to analyze the trajectory of the responses to steps of acceleration. A better representation of the data was obtained from a polynomial that included a cubic term in contrast to an exclusively linear fit. For sinusoidal rotations of 0.5-15 Hz with a peak velocity of 20 degrees /s, the VOR gain measured 0.83 +/- 0.06 and did not vary across frequencies or animals. The phase of these responses was close to compensatory except at 15 Hz where a lag of 5.0 +/- 0.9 degrees was noted. The VOR gain did not vary with head velocity at 0.5 Hz but increased with velocity for rotations at frequencies of >/=4 Hz (0. 85 +/- 0.04 at 4 Hz, 20 degrees /s; 1.01 +/- 0.05 at 100 degrees /s, P < 0.0001). No responses to these rotations were noted in two animals that had undergone bilateral labyrinthectomy indicating that inertia of the eye had a negligible effect for these stimuli. We developed a mathematical model of VOR dynamics to account for these findings. The inputs to the reflex come from linear and nonlinear pathways. The linear pathway is responsible for the constant gain across frequencies at peak head velocity of 20 degrees /s and also for the phase lag at higher frequencies being less than that expected based on the reflex delay. The frequency- and velocity-dependent nonlinearity in VOR gain is accounted for by the dynamics of the nonlinear pathway. A transfer function that increases the gain of this pathway with frequency and a term related to the third power of head

  4. A critical period for functional vestibular development in zebrafish

    NASA Technical Reports Server (NTRS)

    Moorman, Stephen J.; Cordova, Rodolfo; Davies, Sarah A.

    2002-01-01

    We have determined a critical period for vestibular development in zebrafish by using a bioreactor designed by NASA to simulate microgravity for cells in culture. A critical period is defined as the briefest period of time during development when stimulus deprivation results in long lasting or permanent sensory deficits. Zebrafish eggs were collected within 3 hours of being laid and fertilized. In experiment 1, eggs were placed in the bioreactor at 3, 24, 30, 36, 48, or 72 hours postfertilization (hPF) and maintained in the bioreactor until 96 hPF. In experiment 2, eggs were placed in the bioreactor immediately after they were collected and maintained in the bioreactor until 24, 36, 48, 60, 66, 72, or 96 hPF. Beginning at 96 hPF, all larvae had their vestibulo-ocular reflexes (VOR) evaluated once each day for 5 days. Only larvae that hatched from eggs that were placed in the bioreactor before 30 hPF in experiment 1 or removed from the bioreactor later than 66 hPF in experiment 2 had VOR deficits that persisted for at least 5 days. These data suggest a critical period for vestibular development in the zebrafish that begins before 30 hPF and ends after 66 hPF. To confirm this, zebrafish eggs were placed in the bioreactor at 24 hPF and removed at 72 hPF. VORs were evaluated in these larvae once each day for 5 days beginning at 96 hPF. These larvae had VOR deficits that persisted for at least 5 days. In addition, larvae that had been maintained in the bioreactor from 24 to 66 hPF or from 30 to 72 hPF, had only temporary VOR deficits. In a final experiment, zebrafish eggs were placed in the bioreactor at 3 hPF and removed at 96 hPF but the bioreactor was turned off from 24 hPF to 72 hPF. These larvae had normal VORs when they were removed from the bioreactor at 96 hPF. Taken as a whole, these data support the idea that there is a critical period for functional maturation of the zebrafish vestibular system. The developmental period identified includes the timeframe

  5. Visually induced adaptation in three-dimensional organization of primate vestibuloocular reflex

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1998-01-01

    The adaptive plasticity of the spatial organization of the vestibuloocular reflex (VOR) has been investigated in intact and canal-plugged primates using 2-h exposure to conflicting visual (optokinetic, OKN) and vestibular rotational stimuli about mutually orthogonal axes (generating torsional VOR + vertical OKN, torsional VOR + horizontal OKN, vertical VOR + horizontal OKN, and horizontal VOR + vertical OKN). Adaptation protocols with 0.5-Hz (+/-18 degrees ) head movements about either an earth-vertical or an earth-horizontal axis induced orthogonal response components as high as 40-70% of those required for ideal adaptation. Orthogonal response gains were highest at the adapting frequency with phase leads present at lower and phase lags present at higher frequencies. Furthermore, the time course of adaptation, as well as orthogonal response dynamics were similar and relatively independent of the particular visual/vestibular stimulus combination. Low-frequency (0. 05 Hz, vestibular stimulus: +/-60 degrees ; optokinetic stimulus: +/-180 degrees ) adaptation protocols with head movements about an earth-vertical axis induced smaller orthogonal response components that did not exceed 20-40% of the head velocity stimulus (i.e., approximately 10% of that required for ideal adaptation). At the same frequency, adaptation with head movements about an earth-horizontal axis generated large orthogonal responses that reached values as high as 100-120% of head velocity after 2 h of adaptation (i.e., approximately 40% of ideal adaptation gains). The particular spatial and temporal response characteristics after low-frequency, earth-horizontal axis adaptation in both intact and canal-plugged animals strongly suggests that the orienting (and perhaps translational) but not inertial (velocity storage) components of the primate otolith-ocular system exhibit spatial adaptability. Due to the particular nested arrangement of the visual and vestibular stimuli, the optic flow pattern

  6. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. III. Responses after labyrinthectomy

    NASA Technical Reports Server (NTRS)

    Lasker, D. M.; Hullar, T. E.; Minor, L. B.; Shelhamer, M. J. (Principal Investigator)

    2000-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in four squirrel monkeys after unilateral labyrinthectomy. Spontaneous nystagmus was measured at the beginning and end of each testing session. During the period that animals were kept in darkness (4 days), the nystagmus at each of these times measured approximately 20 degrees /s. Within 18-24 h after return to the light, the nystagmus (measured in darkness) decreased to 2.8 +/- 1.5 degrees /s (mean +/- SD) when recorded at the beginning but was 20.3 +/- 3.9 degrees /s at the end of the testing session. The latency of the VOR measured from responses to steps of acceleration (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) was 8.4 +/- 0.3 ms for responses to ipsilesional rotations and 7.7 +/- 0.4 ms for contralesional rotations. During the period that animals were kept in darkness after the labyrinthectomy, the gain of the VOR measured during the steps of acceleration was 0.67 +/- 0.12 for contralesional rotations and 0.39 +/- 0.04 for ipsilesional rotations. Within 18-24 h after return to light, the VOR gain for contralesional rotations increased to 0.87 +/- 0.08, whereas there was only a slight increase for ipsilesional rotations to 0.41 +/- 0. 06. A symmetrical increase in the gain measured at the plateau of head velocity was noted after the animals were returned to light. The VOR evoked by sinusoidal rotations of 2-15 Hz, +/-20 degrees /s, showed a better recovery of gain at lower (2-4 Hz) than at higher (6-15 Hz) frequencies. At 0.5 Hz, gain decreased symmetrically when the peak amplitude was increased from 20 to 100 degrees /s. At 10 Hz, gain was decreased for ipsilesional half-cycles and increased for contralesional half-cycles when velocity was raised from 20 to 50 degrees /s. A model incorporating linear and nonlinear pathways was used to simulate the data. Selective increases in the gain for the linear pathway accounted for the

  7. Baclofen and velocity storage: a model of the effects of the drug on the vestibulo-ocular reflex in the rhesus monkey.

    PubMed

    Cohen, B; Helwig, D; Raphan, T

    1987-12-01

    1. Baclofen had a characteristic effect on vestibular and optokinetic nystagmus in rhesus monkeys. Each aspect of nystagmus that is dependent on the velocity-storage mechanism in the vestibulo-ocular reflex (v.o.r.) was altered by the drug: (a) Baclofen reduced the dominant time constant of the v.o.r. in a dose-dependent manner up to 5 mg/kg, the highest dosage used. The alteration in v.o.r. time constant began within 15 min of injection, was maximal between 1 and 4 h, and lasted for 14-18 h. This effect mirrors changes in plasma levels of baclofen after oral doses in humans (Faigle, Keberle & Agen, 1980). (b) Slow-phase velocities of steady-state nystagmus induced by rotation about axes tilted from the vertical (off-vertical axis rotation, o.v.a.r.) were reduced after baclofen and could not be maintained at previous levels. (c) There was a dose-dependent decline in the steady-state gain of optokinetic nystagmus (o.k.n.), and at the highest dosages little o.k.n. was induced. In parallel, the peak velocity and falling time constant of optokinetic after-nystagmus (o.k.a.n.) were reduced. Since baclofen is a GABA agonist, systems utilizing GABA and acting on GABAB receptors appear to produce inhibitory control of velocity storage. 2. The step gain of the v.o.r., measured at the beginning and end of constant-velocity rotation in darkness, was unaffected by baclofen, as were saccades, quick phases of nystagmus, and the ability to hold positions of fixation or to generate linear slow phases of nystagmus. This indicates that it is possible to use baclofen to manipulate the dominant time constant of the v.o.r. and of o.k.a.n. in relative isolation from effects on other oculomotor components. 3. Baclofen caused a dose-dependent reduction in the initial jump in eye velocity at the onset of o.k.n., suggesting that the initial jump is also under inhibitory control of GABAB receptors. However, there were still occasional slow phases with velocities up to 30-40 deg/s after

  8. Multiple subclasses of Purkinje cells in the primate floccular complex provide similar signals to guide learning in the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Raymond, J. L.; Lisberger, S. G.

    1997-01-01

    The neural "learning rules" governing the induction of plasticity in the cerebellum were analyzed by recording the patterns of neural activity in awake, behaving animals during stimuli that induce a form of cerebellum-dependent learning. We recorded the simple- and complex-spike responses of a broad sample of Purkinje cells in the floccular complex during a number of stimulus conditions that induce motor learning in the vestibulo-ocular reflex (VOR). Each subclass of Purkinje cells carried essentially the same information about required changes in the gain of the VOR. The correlation of simple-spike activity in Purkinje cells with activity in vestibular pathways could guide learning during low-frequency but not high-frequency stimuli. Climbing fiber activity could guide learning during all stimuli tested but only if compared with the activity present approximately 100 msec earlier in either vestibular pathways or Purkinje cells.

  9. Development of the Roll-Induced Vestibuloocular Reflex in the Absence of Vestibular Experience in Salamander Tadpoles (Pleurodeles Waltl)

    NASA Astrophysics Data System (ADS)

    Horn, Eberhard R.; Gabriel, Martin; Frippiat, Jean-Pol

    2008-06-01

    The macula organ of the labyrinth is stimulated by body roll or translatory movements. Due to its slow development, the salamander Pleurodeles waltl is an excellent model to study the impact of microgravity on the development of the roll-induced vestibuloocular reflex (rVOR) in the absence of any macular stimulation. The experiment was performed during the Soyuz mission TMA8 (return flight TMA7) in 2006 as part of the experiment AMPHIBODY. It was supplemented by a 3g-hypergravity experiment. It was shown, that microgravity retards the over-all development of Pleurodeles tadpoles but not specifically functional development of the vestibular system; normalization took place within 3 to 4 weeks after landing. Hypergravity accelerated rVOR development in the long-term frame.

  10. Flight evaluation of advanced navigation techniques for general aviation using frequency scanning

    NASA Technical Reports Server (NTRS)

    Jackson, C. T., Jr.; Denery, D. G.; Korsak, A. J.; Conrad, B.

    1976-01-01

    Experiments on an automatic multisensor navigation concept are being conducted in a Cessna 402B. The test system consists of VOR, DME, and air data sensors controlled by a Hewlett Packard 9820A electronic calculator which processes the data and, by means of a four-state Kalman filter, outputs position and ground and wind velocities to a map display. Novel features which make such a system potentially low-cost include frequency-scanning operation of a single VOR receiver and a single DME transceiver and use of a shed-vortex true airspeed sensor. Results obtained during flight in a local area where six to eight DME NAVAIDS were receivable yielded better than 1/4-mile accuracy.

  11. Adaptation of primate vestibuloocular reflex to altered peripheral vestibular inputs. II Spatiotemporal properties of the adapted slow-phase eye velocity

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1996-01-01

    1. The ability of the vestibuloocular reflex (VOR) to undergo adaptive modification after selective changes in the peripheral vestibular system was investigated in rhesus monkeys by recording three-dimensional eye movements before and after inactivation of selective semicircular canals. In the preceding paper we showed that the horizontal VOR gain evoked by passive yaw oscillations after lateral semicircular canal inactivation recovers gradually over time in a frequency-specific manner. Here we present the spatial tuning of the adapted slow-phase eye velocity and describe its spatiotemporal properties as a function of time after canal inactivation. 2. The spatial organization of the VOR was investigated during oscillations at different head positions in the pitch, roll, and yaw planes, as well as in the right anterior/left posterior and left anterior/right posterior canal planes. Acutely after bilateral inactivation of the lateral semicircular canals, a small horizontal response could still be elicited that peaked during rotations in pitched head positions that would maximally stimulate vertical semicircular canals. In addition, the phase of horizontal slow-phase velocity abruptly reversed through 180 degrees at positions close to upright, similarly to torsional slow-phase velocity. These spatial response properties suggest that the small, residual horizontal response components that are present acutely after plugging of both lateral canals originate from vertical semicircular canal signals. 3. As the horizontal response amplitude increased over time, consistent changes were also observed in the spatiotemporal tuning of horizontal slow-phase velocity. 1) The spatiotemporal response properties of horizontal slow-phase velocity acquired noncosine tuning characteristics, primarily in the pitch plane, in the right anterior/left posterior and left anterior/right posterior canal planes. Accordingly, horizontal response amplitude was nonzero during rotation in any head

  12. Regenerative Energieträger im Aufwind: Entwicklung der erneuerbaren Energien

    NASA Astrophysics Data System (ADS)

    Kohl, Harald

    2006-05-01

    2005 kam 4,6 % des deutschen Primär-Energieverbrauchs aus erneuerbaren Energiequellen, bei der Stromproduktion lag ihr Anteil bei 10,2 %. Wesentliche Ursache ist der Boom bei der Windkraft, die vor allem durch Offshore-Windparks auf See weiter ausbaubar ist. Die Wasserkraft lieferte in Deutschland traditionell einen großen Beitrag zur Stromerzeugung, doch ihr Ausbaupotenzial ist gering. Die Photovoltaik, die solar- und die geothermische Stromerzeugung spielen derzeit noch eine kleine Rolle. Den deutschen Bedarf an Wärmeenergie deckten 2004 die erneuerbaren Energien zu 5,4 %, vor allem aus Biomasse. Die solarthermische Wärmeerzeugung hat sich gegenüber 2000 mehr als verdoppelt. Im Straßenverkehr spielen biogene Kraftstoffe mit 5,4 % noch eine untergeordnete Rolle. Bis 2050 könnte in Deutschland der Anteil regenerativer Energien am Primär-Energieverbrauch die Fünfzigprozentmarke überschreiten.

  13. Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags.

    PubMed

    Rokunuzzaman, Md; Islam, Mohammad Tariqul; Rowe, Wayne S T; Kibria, Salehin; Jit Singh, Mandeep; Misran, Norbahiah

    2016-01-01

    A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919-923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for 'place and tag' application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP). PMID:27533470

  14. Victim-Offender Relationship Status Moderates the Relationships of Peritraumatic Emotional Responses, Active Resistance, and Posttraumatic Stress Symptomatology in Female Rape Survivors.

    PubMed

    Feinstein, Brian A; Humphreys, Kathryn L; Bovin, Michelle J; Marx, Brian P; Resick, Patricia A

    2011-06-01

    This study examined whether the level of victim-offender relationship (VOR) moderated the relationship between peritraumatic fear and active resistance as well as the relationship between peritraumatic fear and posttraumatic stress symptom severity in a community sample of female rape survivors. One hundred thirty-five participants were interviewed about their emotional and behavioral responses during the rape and assessed for posttraumatic stress symptomatology within one month of the assault. Results indicated that peritraumatic fear was positively associated with active resistance, but only among survivors of acquaintance rape. Additionally, peritraumatic fear was positively associated with posttraumatic stress symptom severity, but only among survivors of intimate partner rape. These results suggest that VOR may be an important contextual factor that influences emotional and behavioral responses during rape as well as posttraumatic stress symptomatology in its aftermath. PMID:21731797

  15. Anatomical and Physiological Considerations in Vestibular Dysfunction and Compensation

    PubMed Central

    Jones, Sherri M.; Jones, Timothy A.; Mills, Kristal N.; Gaines, G. Christopher

    2010-01-01

    Sensory information from the vestibular, visual, and somatosensory/proprioceptive systems are integrated in the brain in complex ways to produce a final motor output to muscle groups for maintaining gaze, head and body posture, and controlling static and dynamic balance. The balance system is complex, which can make differential diagnosis of dizziness quite challenging. On the other hand, this complex system is organized anatomically in a variety of pathways and some of these pathways have been well studied. The vestibulo-ocular reflex (VOR) is one such pathway. Understanding the anatomy and physiology of the VOR facilitates our understanding of normal and abnormal eye movements and research is advancing our understanding of the plasticity of the vestibular system. This review highlights anatomical and physiological features of the normal vestibular system, applies these concepts to explain some clinical findings in some common peripheral vestibular disorders, and discusses some of the research investigating the anatomical and physiological basis for vestibular compensation. PMID:21072129

  16. The Chinchilla's vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Merwin, W. H., Jr.; Wall, Conrad, III; Tomko, D. L.

    1989-01-01

    The horizontal vestibulo-ocular reflex (VOR) was measured and characterized in seven adult chinchillas using 0.01 to 1.0 Hz angular velocity sinusoids. Gains were less than compensatory, and were variable from day to day, but phases were highly repeatable both within and between animals. The best fitting transfer function to the average data of all animals had a dominant time constant of 7.5 sec, and an adaptation operator with a time constant of 24.0 sec. There were certain nonlinearities in the horizontal VOR of this animal, and it was difficult to elicit a robust optokinetic response. Results are discussed in relation to similar measurements in other species.

  17. Einführung in die Renaturierungsökologie

    NASA Astrophysics Data System (ADS)

    Zerbe, Stefan; Wiegleb, Gerhard; Rosenthal, Gert

    Durch die übernutzung der Naturressourcen sind heute weltweit viele natürliche wie auch durch Kultur entstandene ökosysteme und Landschaften in ihren Funktionen und Leistungen stark beeinträchtigt oder sogar völlig zerstört. Bereits vor mehr als einem Jahrzehnt konstatierte (1995), dass ca. 45 % der terrestrischen Landoberfläche nur eine reduzierte Kapazität für die zukünftige Landnutzung haben. Als Grund hob er eine in der Vergangenheit nicht nachhaltige Landbewirtschaftung hervor. Mit einer gezielten Renaturierung der betroffenen ökosysteme soll dieser Trend umgekehrt werden (Harris und van Diggelen 2006). Vor diesem Hintergrund ist die ökosystemrenaturierung (ecological restoration) wichtiger Bestandteil der Planungs- und Naturschutzpraxis in Mitteleuropa und die Renaturierungsökologie (restoration ecology) zu einer eigenen wissenschaftlichen Arbeitsrichtung geworden.

  18. Control of ocular torsion in the rotational vestibulo-ocular reflexes.

    PubMed

    Hess, Bernhard J M

    2008-01-01

    Visual stabilization of the retina during rotational head movements requires that in far vision the eyes rotate about the same axis as the head but in opposite direction with a gain close to unity (optimal strategy). To achieve this goal the vestibulo-oculomotor system must be able to independently control all three rotational degrees of freedom of the eye. Studies of the human rotational vestibulo-ocular reflexes (VOR) have shown that its spatial characteristics are best explained by a strategy that lies halfway between the optimal image stabilization and perfect compliance with Listing's law. Here we argue that these spatial characteristics are fully compatible with an optimal strategy under the condition of a restrained gain of the torsional velocity-to-position integration. One implication of this finding is that the rotational VORs must override the default operation mode of the ocular plant that, according to recent findings, mechanically favours movements obeying Listing's law. PMID:18718301

  19. Geobasisdaten für die Planung?

    NASA Astrophysics Data System (ADS)

    Zölitz-Möller, Reinhard

    2002-09-01

    Die Nutzer von Geobasisdaten der Vermessungs- und Katasterverwaltungen finden heute vor allem in ATKIS (Amtliches Topographisch-Kartographisches Informationssystem) und in der ALK (automatisiert geführte Liegenschaftskarte; hier noch eingeschränkt) flächendeckende und für eine Fachdatenintegration geeignete Geodatenbestände vor. Gleichwohl wird von Nutzerseite häufig ein differenziertes und in Teilen kritisches Bild gezeichnet. Die Kritik richtet sich v.a. auf die Probleme, die ATKIS-Anwender mit dem Nutzerkomfort, dem komplexen Datenmodell, unrichtigen Flächennutzungsangaben, inkompatiblen Objektdefinitionen, den Preisen sowie mangelnder Aktualität und Vollständigkeit haben. Dennoch gibt es für viele Zwecke auch in der Planung langfristig keine echte Alternative zu den Geobasisdaten.

  20. Effects of digital altimetry on pilot workload

    NASA Technical Reports Server (NTRS)

    Harris, R. L., Sr.; Glover, B. J.

    1984-01-01

    A series of VOR-DME instrument landing approaches was flown in the DC-9 full-workload simulator to compare pilot performance, scan behavior, and workload when using a computer-drum-pointer altimeter (CDPA) and a digital altimeter (DA). Six pilots executed two sets of instrument landing approaches, with a CDPA on one set and a DA on the other set. Pilot scanning parameters, flight performance, and subjective opinion data were evaluated. It is found that the processes of gathering information from the CDPA and the DA are different. The DA requires a higher mental workload than the CDPA for a VOR-DME type landing approach. Mental processing of altitude information after transitioning back to the attitude indicator is more evident with the DA than with the CDPA.

  1. Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags

    PubMed Central

    Islam, Mohammad Tariqul; Rowe, Wayne S. T.; Kibria, Salehin; Jit Singh, Mandeep; Misran, Norbahiah

    2016-01-01

    A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919–923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for ‘place and tag’ application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP). PMID:27533470

  2. Simulation und virtuelle Realität

    NASA Astrophysics Data System (ADS)

    von Estorff, Otto; Markiewicz, Marian; Özkan, Ali; Zaleski, Olgierd; Blumrich, Reinhard; Genuit, Klaus; Fiebig, André

    Mit Hilfe akustischer Berechnungen ist es möglich, aufwendige Messungen an Fahrzeugprototypen deutlich zu reduzieren. Dieses Kapitel gibt einen kurzen Überblick über die wichtigsten derzeit verfügbaren Methoden. Dabei wird zunächst auf Elementverfahren, wie die Finite-Elemente-Methode (FEM) und die Boundary-Elemente-Methode (BEM), näher eingegangen. Während diese vor allem im tieffrequenten Bereich eingesetzt werden, kommen bei höheren Frequenzen vermehrt Verfahren zum Einsatz, die auf Energieformulierungen beruhen. Exemplarisch wird hier die Funktionsweise und der Einsatz der Statistischen-Energie-Analyse (SEA) erläutert. Anhand von repräsentativen Beispielen werden die Einsatzmöglichkeiten und Grenzen der verschiedenen Verfahren aufgezeigt, wobei vor allem auch auf Vergleiche zwischen Rechnung und Messung eingegangen wird.

  3. Motor function in microgravity: movement in weightlessness

    NASA Technical Reports Server (NTRS)

    Lackner, J. R.; DiZio, P.

    1996-01-01

    Microgravity provides unique, though experimentally challenging, opportunities to study motor control. A traditional research focus has been the effects of linear acceleration on vestibular responses to angular acceleration. Evidence is accumulating that the high-frequency vestibulo-ocular reflex (VOR) is not affected by transitions from a 1 g linear force field to microgravity (<1 g); however, it appears that the three-dimensional organization of the VOR is dependent on gravitoinertial force levels. Some of the observed effects of microgravity on head and arm movement control appear to depend on the previously undetected inputs of cervical and brachial proprioception, which change almost immediately in response to alterations in background force levels. Recent studies of post-flight disturbances of posture and locomotion are revealing sensorimotor mechanisms that adjust over periods ranging from hours to weeks.

  4. Etiologic Agents and Antifungal Susceptibility of Oral Candidosis from Romanian patients with HIV-infection or type 1 diabetes mellitus.

    PubMed

    Minea, Bogdan; Nastasa, Valentin; Kolecka, Anna; Mares, Magdalena; Marangoci, Narcisa; Rosca, Irina; Pinteala, Mariana; Hancianu, Monica; Mares, Mihai

    2016-01-01

    This is the first Romanian investigation of oral candidosis in patients suffering of HIV-infection or type 1 diabetes mellitus (T1DM). Candida albicans was the dominant species in both types of isolates: n = 14 (46.7%) in T1DM, n = 60 (69.8%) in HIV. The most frequent non-albicans Candida spp. were Candida kefyr (n = 6; 20%) in T1DM and Candida dubliniensis (n = 8; 9.3%) in HIV. Resistance to fluconazole was detected only in the HIV non-albicans Candida group (n = 8; 9.3%). All isolates were susceptible to VOR. The experimental drug MXP had MIC values equal or close to the ones of VOR. Echinocandin resistance was more frequent than azole resistance. PMID:27282005

  5. SARCOPTERYGII, Fleischflosser

    NASA Astrophysics Data System (ADS)

    Schultze, Hans-Peter

    Unter den rezenten und fossilen Fischen sind die Sarcopterygier durch fleischige Loben an den paarigen Flossen charakterisiert. Fossil gehen sie bis in das Obere Silur (vor 420 Mio. Jahren) zurück. Einige Gruppen (†Onychodontida, †Porolepiformes, †Elpistostegalia) waren auf das Devon beschränkt, andere verschwanden gegen Ende des Paläozoikums (†Rhizodontida, †Osteolepiformes). Nur wenige Arten der Dipnoi (Lungenfische) und Actinistia (Hohlstachler) haben überlebt; aus einer ausgestorbenen Teilgruppe evolvierten die erfolgreichen Tetrapoda. Im Devon waren die Sarcopterygier weltweit verbreitet; ihre rezenten fischartigen Formen sind dagegen auf die Südkontinente bzw. den Indischen Ozean beschränkt. Ursprünglich waren alle Formen marin. Mehrmals unabhängig wurde von ihnen das Süßwasser und innerhalb der Tetrapoden vor allem das Land erobert.

  6. "Das Konkrete ist das Abstrakte, an das man sich schließlich gewöhnt hat." (Laurent Schwartz) Über den Ablauf des mathematischen Verstehens

    NASA Astrophysics Data System (ADS)

    Lowsky, Martin

    Die im Titel genannte Aussage findet sich in den Lebenserinnerungen von Laurent Schwartz (1915-2002), einem der fruchtbarsten Mathematiker, Mitglied der Gruppe Bourbaki. Im Original lautet die Aussage: "un objet concret est un objet abstrait auquel on a fini par s'habituer." Schwartz erläutert sie am Beispiel des Integrals über {e^{-1/2{x^2}}} , das den Wert Wurzel aus 2π hat und in dem sich also die Zahlen e und π verknüpfen. Was Schwartz aber vor allem ausdrücken will, ist dies: Das mathematische Verständnisd geht langsam vor sich und es bedarf der Anstrengung. "Es ist eine Frage der Zeit und der Energie", sagt Schwartz, und gerade dies mache es so schwer, die höhere Mathematik unter das Volk zu bringen. Das Lernen und Lehren von Mathematik laufe eben mühevoll und langsam ab.

  7. Navigation Signal Disturbances by Multipath Propagation - Scaled Measurements with a Universal Channel Sounder Architecture

    NASA Astrophysics Data System (ADS)

    Geise, Robert; Neubauer, Bjoern; Zimmer, Georg

    2015-11-01

    The performance of navigation systems is always reduced by unwanted multipath propagation. This is especially of practical importance for airborne navigation systems like the instrument landing system (ILS) or the VHF omni directional radio range (VOR). Nevertheless, the quantitative analysis of corresponding, potentially harmful multipath propagation disturbances is very difficult due to the large parameter space. Experimentally difficulties arise due to very expensive, real scale measurement campaigns and numerical simulation techniques still have shortcomings which are briefly discussed. In this contribution a new universal approach is introduced on how to measure very flexibly multipath propagation effects for arbitrary navigation systems using a channel sounder architecture in a scaled measurement environment. Two relevant scenarios of multipath propagation and the impact on navigation signals are presented. The first describes disturbances of the ILS due to large taxiing aircraft. The other example shows the influence of rotating wind turbines on the VOR.

  8. Victim-Offender Relationship Status Moderates the Relationships of Peritraumatic Emotional Responses, Active Resistance, and Posttraumatic Stress Symptomatology in Female Rape Survivors

    PubMed Central

    Feinstein, Brian A.; Humphreys, Kathryn L.; Bovin, Michelle J.; Marx, Brian P.; Resick, Patricia A.

    2010-01-01

    This study examined whether the level of victim-offender relationship (VOR) moderated the relationship between peritraumatic fear and active resistance as well as the relationship between peritraumatic fear and posttraumatic stress symptom severity in a community sample of female rape survivors. One hundred thirty-five participants were interviewed about their emotional and behavioral responses during the rape and assessed for posttraumatic stress symptomatology within one month of the assault. Results indicated that peritraumatic fear was positively associated with active resistance, but only among survivors of acquaintance rape. Additionally, peritraumatic fear was positively associated with posttraumatic stress symptom severity, but only among survivors of intimate partner rape. These results suggest that VOR may be an important contextual factor that influences emotional and behavioral responses during rape as well as posttraumatic stress symptomatology in its aftermath. PMID:21731797

  9. Effects of digital altimetry on pilot workload

    NASA Technical Reports Server (NTRS)

    Harris, R. L., Sr.; Glover, B. J.

    1985-01-01

    A series of VOR-DME instrument landing approaches was flown in the DC-9 full-workload simulator to compare pilot performance, scan behavior, and workload when using a computer-drum-pointer altimeter (CDPA) and a digital altimeter (DA). Six pilots executed two sets of instrument landing approaches, with a CDPA on one set and a DA on the other set. Pilot scanning parameters, flight performance, and subjective opinion data were evaluated. It is found that the processes of gathering information from the CDPA and the DA are different. The DA requires a higher mental workload than the CDPA for a VOR-DME type landing approach. Mental processing of altitude information after transitioning back to the attitude indicator is more evident with the DA than with the CDPA.

  10. Lack of effects of astemizole on vestibular ocular reflex, motion sickness, and cognitive performance in man

    NASA Technical Reports Server (NTRS)

    Kohl, Randall L.; Homick, Jerry L.; Cintron, Nitza; Calkins, Dick S.

    1987-01-01

    Astemizole was orally administered to 20 subjects in a randomized, double-blind design to assess the efficacy of this peripherally active antihistamine as an antimotion sickness drug possessing no central side-effects. Measures of vestibular ocular reflex (VOR) were made to evaluate the agent as a selective vestibular depressant. Following one week of orally administered astemizole (30 mg daily), a Staircase Profile Test, a VOR test, and a variety of tests of cognitive performance were administered. These tests revealed no statistically significant effects of astemizole. This leads to the conclusion that, although the drug probably reaches the peripheral vestibular apparatus in man by crossing the blood-vestibular barrier, a selective peripheral antihistamine (H1) action is inadequate to control motion sickness induced through cross-coupled accelerative semicircular canal stimulation in a rotating chair.

  11. 78 FR 40385 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-05

    ... regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of... RNAV (GPS) RWY Intl. 34, Amdt 2A. 7/25/13 AR Lake Village.... Lake Village 3/0451 6/13/13 VOR-A, Amdt 8. Muni. 7/25/13 AR Lake Village.... Lake Village 3/0452 6/13/13 RNAV (GPS) RWY Muni. 1, Orig. 7/25/13...

  12. Ist da jemand? Wie Außerirdische uns entdecken können

    NASA Astrophysics Data System (ADS)

    Heller, R.

    2016-06-01

    Astronomen schlagen vor, sich bei der Suche nach Signalen außerirdischer Zivilisationen auf einen schmalen Bereich am Himmel zu konzentrieren. Von Planeten um Sterne, die in diesem Streifen liegen, würde sich die Erde vergleichsweise leicht entdecken lassen. Sollte es dort intelligentes Leben geben, könnte uns dieses schon längst aufgespürt und eine Botschaft Richtung Erde geschickt haben.

  13. Johannes Kepler

    NASA Astrophysics Data System (ADS)

    Bialas, Volker

    Johannes Kepler (1571 - 1630) gilt zurecht als einer der bedeutendsten Mathematiker und Astronomen der frühen Neuzeit, doch wurde das Philosophische in seinem Werk bislang kaum in angemessener Weise gewürdigt. Volker Bialas legt eine fundierte und anregende Einführung in Leben, Werk und Weltanschauung Keplers vor und setzt dabei durch die Akzentuierung des philosophisch-ganzheitlichen Denkens bewußt einen Kontrapunkt zum herkömmlichen Kepler-Bild.

  14. Labyrinthine lesions and motion sickness susceptibility

    PubMed Central

    Raphan, Theodore; Cohen, Bernard

    2011-01-01

    The angular vestibulo-ocular reflex (aVOR) has a fast pathway, which mediates compensatory eye movements, and a slow (velocity storage) pathway, which determines its low frequency characteristics and orients eye velocity toward gravity. We have proposed that motion sickness is generated through velocity storage, when its orientation vector, which lies close to the gravitational vertical, is misaligned with eye velocity during head motion. The duration of the misalignment, determined by the dominant time constant of velocity storage, causes the buildup of motion sickness. To test this hypothesis, we studied bilateral labyrinthine-defective subjects with short vestibular time constants but normal aVOR gains for their motion sickness susceptibility. Time constants and gains were taken from rotational responses. Motion sickness was generated by rolling the head while rotating, and susceptibility was assessed by the number of head movements made before reaching intolerable levels of nausea. More head movements signified lower motion sickness susceptibility. Labyrinthine-defective subjects made more head movements on their first exposure to roll while rotating than normals (39.8 ± 7.2 vs 13.7 ± 5.5; P < 0.0001). Normals were tested eight times, which habituated their time constants and reduced their motion sickness susceptibility. Combining data from all subjects, there was a strong inverse relationship between time constants and number of head movements (r = 0.94), but none between motion sickness susceptibility and aVOR gains. This provides further evidence that motion sickness is generated through velocity storage, not the direct pathway, and suggests that motion sickness susceptibility can be reduced by reducing the aVOR time constant. PMID:17256169

  15. Wasserkraftwerke

    NASA Astrophysics Data System (ADS)

    Zahoransky, Richard; Allelein, Hans-Josef; Bollin, Elmar; Oehler, Helmut; Schelling, Udo

    Die Wasserkraft ist global die bedeutendste erneuerbare Energiequelle. Sie hat in Deutschland einen stagnierenden Anteil von ca. 5 % der gesamten Stromerzeugung (Bild 1.2). In Deutschland wurde die Wasserkraft allerdings bei der Stromerzeugung durch die Windkraft und vor kurzem sogar von der Biomassevergasung überholt. Die Wasserkraft ist andererseits eine gut berechenbare Energiequelle und unterliegt nicht den nur kurzfristig vorhersehbaren Schwankungen der Wind- und Solarenergien.

  16. 78 FR 59810 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-30

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... CAT I), Amdt 7 10/17/13 AK Savoonga Savoonga 3/3472 8/29/13 VOR/DME RWY 23, Amdt 1A 10/17/13 AK... City Intl. 3/4342 8/29/13 ILS OR LOC RWY 16R, ILS RWY 16R (SA CAT I), ILS RWY 16R (CAT II & III),...

  17. 14 CFR 93.350 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... drawn direct to the southwestern tip of Governors Island, thence north along a line direct to the southwest tip of Manhattan Island, thence north along the west bank of the East River to the LGA VOR/DME 6... along the east bank of the East River to the point of beginning at lat. 40°38′39″ N., long 74°02′03″...

  18. 75 FR 76648 - Proposed Establishment of Area Navigation (RNAV) Routes; Western United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-09

    ... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959....) EKR VOR/DME (Lat. 40 04'03'' N., long. 107 55'30'' W.) * * * * * Q-128 LIN to MEM LIN VORTAC (Lat....

  19. Stationäre Motorvermessung mit verschiedenen Methoden und Modellen

    NASA Astrophysics Data System (ADS)

    Kötter, Hinrich; Sequenz, Heiko

    Die kontinuierliche Verschärfung der gesetzlichen Vorgaben bezüglich Emissionen stellt die Motorenentwickler vor neue Herausforderungen (Bild 6-1, [1, 2]). Gleichzeitig ist zu erwarten, dass sich der langfristige Trend der letzten Jahren bei den Kraftstoffpreisen [3] trotz kurzzeitiger Schwankungen fortsetzen wird (Bild 6-1 rechts, Jahresmittelwerte). Auf die steigenden Kraftstoffpreise sowie die Verpflichtungen bezüglich der CO2- Emissionswerte kann dauerhaft nur mit Kraftstoff sparenden Motoren reagiert werden.

  20. Pierre Curie - ein Leben für die Forschung. Physikgeschichte

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2006-05-01

    Vor hundert Jahren starb Pierre Curie, der einer ganzen Forscherdynastie seinen Namen gegeben hat. In vielen Gebieten, wie der Piezoelektrizität, der Kristallographie, der magnetischen Eigenschaften von Körpern sowie der Erforschung der Radioaktivität gelangen ihm bahnbrechende Entdeckungen. Darüber hinaus entwickelte er eine Reihe von experimentellen Apparaturen. Auf allen diesen Feldern leistete er Pionierarbeit und setzte neue Maßstäbe.

  1. Was wissen wir über Information?

    NASA Astrophysics Data System (ADS)

    Engelmann, Florian; Großmann, Christoph

    Der Begriff Information stammt aus dem Lateinischen. Von der Antike bis in das 20. Jahrhundert war Information ein kaum verwendetes und unspektakuläres Wort. ZEMANEK belegt diese Hypothese mit dem Verweis auf ein Häufigkeitswörterbuch der deutschen Sprache aus dem Jahre 1897. Dort kommt in ca. 11 Millionen Wörten nur 55 mal das Wort Information vor [Zemanek 1986, S. 19].

  2. Alternative Nachweisverfahren - nicht PCR-basierende Schnellmethoden

    NASA Astrophysics Data System (ADS)

    Schalch, Barbara; Wagner, Martin

    Die Erfolge moderner mikrobiologischer Schnellmethoden stellen Sensitivität und Spezifität vieler konventioneller mikrobiologischer Kultivierungsmethoden in Frage. Konventionell ermittelte Keimzahlen und -gruppen pro Untersuchungseinheit scheinen mehr oder weniger unter den realen Gegebenheiten zu liegen. Andererseits schreibt beispielsweise die EU-weit geltende Verordnung (EG) Nr. 2073/2005 über mikrobiologische Kriterien für Lebensmittel den Einsatz einiger dieser Nachweismethoden verbindlich vor.

  3. Führungs- und Teamverhalten

    NASA Astrophysics Data System (ADS)

    Ebermann, Hans-Joachim; Scheiderer, Joachim

    Mc. Broom war ein tyrannischer Chef, der seine Mitarbeiter mit seiner Launenhaftigkeit einschüchterte. Das wäre vielleicht nicht aufgefallen, hätte Mc. Broom in einem Büro oder in einer Fabrik gearbeitet. Aber Mc. Broom war Flugkapitän. <¼> Seine Copiloten fürchteten sich so sehr vor seinem Zorn, dass sie nichts sagten. Nicht einmal als die Katastrophe absehbar war. Beim Absturz der Maschine kamen zehn Menschen zu Tode (Goleman 2001).

  4. Ausbildung als zentrale Aufgabe

    NASA Astrophysics Data System (ADS)

    Krämer, Walter; Schmerbach, Sibylle

    Anders als Lesen und Schreiben zählen Grundkenntnisse in Statistik heute noch nicht zu den Voraussetzungen einer sinnvollen Teilhabe am Sozialgeschehen. Und auch in der akademischen Statistik-Ausbildung gibt es noch einiges zu tun. Das vorliegende Kapitel zeichnet die Geschichte dieser akademischen Ausbildung an deutschen Universitäten nach dem zweiten Weltkrieg nach, stellt aktuelle Defizite vor und weist auf mögliche Verbesserungen hin.

  5. Physiology of Developing Gravity Receptors and Otolith-Ocular Reflexes in Rat

    NASA Technical Reports Server (NTRS)

    Blanks, Robert H.

    1997-01-01

    This proposal had the long-term objective of examining the effects of microgravity on the physiology of the adult and developing mammalian gravity receptors. The grant outlined three-years of ground-based studies to examine. 1) the physiologic responses or otolith afferents in the adult rat and during postnatal development, and 2) the otolith organ contributions to the vertical vestibulo-ocular (VOR) and postural reflexes.

  6. Finanzierung des Studiums

    NASA Astrophysics Data System (ADS)

    Domnick, Ivonne

    "Das liebe Geld“ - ein Thema, das Sie durch das ganze Studium begleitet und auch in der Examensphase und bei der späteren Berufswahl eine entscheidende Rolle spielen wird. Naturwissenschaftler und Ingenieure haben auf dem Arbeitsmarkt sicher derzeit die Nase vorn und brauchen sich über ihre berufliche Zukunft nicht so große Gedanken machen. Doch vor der Karriere muss zunächst einmal eine sichere Studienfinanzierung auf die Beine gestellt werden.

  7. Readaptation of the Vestibulo-Ocular Reflex Relieves the Mal De Debarquement Syndrome

    PubMed Central

    Dai, Mingjia; Cohen, Bernard; Smouha, Eric; Cho, Catherine

    2014-01-01

    The mal de debarquement syndrome (MdDS), a continuous feeling of swaying, rocking, and/or bobbing, generally follows travel on the sea. The associated symptoms cause considerable distress. The underlying neural mechanisms are unknown, and to date there have been no effective treatments for this condition. Results in monkeys and humans suggested that MdDS was caused by maladaptation of the vestibulo-ocular reflex (VOR) to roll of the head during rotation. We studied 24 subjects with persistent MdDS (3 males, 21 females; 19.1 ± 33 months). Physical findings included body oscillation at 0.2 Hz, oscillating vertical nystagmus when the head was rolled from side-to-side in darkness, and unilateral rotation during the Fukuda stepping test. We posited that the maladapted rocking and the physical symptoms could be diminished or extinguished by readapting the VOR. Subjects were treated by rolling the head from side-to-side while watching a rotating full-field visual stimulus. Seventeen of the 24 subjects had a complete or substantial recovery on average for approximately 1 year. Six were initially better, but the symptoms recurred. One subject did not respond to treatment. Thus, readaptation of the VOR has led to a cure or substantial improvement in 70% of the subjects with MdDS. We conclude that the adaptive processes associated with roll-while-rotating are responsible for producing MdDS, and that the symptoms can be reduced or resolved by readapting the VOR. PMID:25076935

  8. Modeling the vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt.

    PubMed

    Merfeld, D M

    1995-01-01

    Model simulations of the squirrel monkey vestibulo-ocular reflex (VOR) are presented for two motion paradigms: constant velocity eccentric rotation and roll tilt about a naso-occipital axis. The model represents the implementation of three hypotheses: the "internal model" hypothesis, the "gravito-inertial force (GIF) resolution" hypothesis, and the "compensatory VOR" hypothesis. The internal model hypothesis is based on the idea that the nervous system knows the dynamics of the sensory systems and implements this knowledge as an internal dynamic model. The GIF resolution hypothesis is based on the idea that the nervous system knows that gravity minus linear acceleration equals GIF and implements this knowledge by resolving the otolith measurement of GIF into central estimates of gravity and linear acceleration, such that the central estimate of gravity minus the central estimate of acceleration equals the otolith measurement of GIF. The compensatory VOR hypothesis is based on the idea that the VOR compensates for the central estimates of angular velocity and linear velocity, which sum in a near-linear manner. During constant velocity eccentric rotation, the model correctly predicts that: (1) the peak horizontal response is greater while "facing-motion" than with "back-to-motion"; (2) the axis of eye rotation shifts toward alignment with GIF; and (3) a continuous vertical response, slow phase downward, exists prior to deceleration. The model also correctly predicts that a torsional response during the roll rotation is the only velocity response observed during roll rotations about a naso-occipital axis. The success of this model in predicting the observed experimental responses suggests that the model captures the essence of the complex sensory interactions engendered by eccentric rotation and roll tilt. PMID:8542968

  9. Modeling the vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1995-01-01

    Model simulations of the squirrel monkey vestibulo-ocular reflex (VOR) are presented for two motion paradigms: constant velocity eccentric rotation and roll tilt about a naso-occipital axis. The model represents the implementation of three hypotheses: the "internal model" hypothesis, the "gravito-inertial force (GIF) resolution" hypothesis, and the "compensatory VOR" hypothesis. The internal model hypothesis is based on the idea that the nervous system knows the dynamics of the sensory systems and implements this knowledge as an internal dynamic model. The GIF resolution hypothesis is based on the idea that the nervous system knows that gravity minus linear acceleration equals GIF and implements this knowledge by resolving the otolith measurement of GIF into central estimates of gravity and linear acceleration, such that the central estimate of gravity minus the central estimate of acceleration equals the otolith measurement of GIF. The compensatory VOR hypothesis is based on the idea that the VOR compensates for the central estimates of angular velocity and linear velocity, which sum in a near-linear manner. During constant velocity eccentric rotation, the model correctly predicts that: (1) the peak horizontal response is greater while "facing-motion" than with "back-to-motion"; (2) the axis of eye rotation shifts toward alignment with GIF; and (3) a continuous vertical response, slow phase downward, exists prior to deceleration. The model also correctly predicts that a torsional response during the roll rotation is the only velocity response observed during roll rotations about a naso-occipital axis. The success of this model in predicting the observed experimental responses suggests that the model captures the essence of the complex sensory interactions engendered by eccentric rotation and roll tilt.

  10. Physik gestern und heute Vom Arbeitshaus zur Supernova

    NASA Astrophysics Data System (ADS)

    Heering, Peter

    2004-01-01

    In der letzten Ausgabe stellten wir einige Arbeiten des Grafen von Rumford vor. Unter seinen vielfältigen Entwicklungen findet sich auch die Beschreibung eines der ersten Photometer. Diese Arbeiten aus dem Jahre 1792 führten letztlich zu einer Definition der Lichtstärke, die lange Zeit gebräuchlich war. Rumfords Konzept der Standardkerze findet sich heute unter anderem in der Astronomie wieder.

  11. Kultivierungsverfahren für Bakterien

    NASA Astrophysics Data System (ADS)

    Messelhäußer, Ute

    Lange Zeit war die Isolierung bakterieller pathogener Mikroorganismen mithilfe von entsprechenden Nährmedien die einzige Möglichkeit zum Nachweis der Erreger in Lebensmittel-, Human- und Veterinärproben. Diese Vorgehensweise wurde Mitte des 19. Jahrhunderts entwickelt. Damals gehörte Louis Pasteur zu den ersten Mikrobiologen, die es für notwendig erachteten, Krankheitserreger auch außerhalb des menschlichen Körpers kultivieren zu können und entwickelte deshalb 1861 die erste flüssige Anreicherungsbouillon [7]. Er legte damit einen der Grundsteine für die heutige mikrobiologische Diagnostik und alle weiteren, darauf aufbauenden Disziplinen. Grundlage der modernen bakteriellen Lebensmittelsuntersuchung sind, im Gegensatz zur viralen Diagnostik, nach wie vor entsprechende Anreicherungsschritte. Vor allem die oftmals sehr geringe Infektionsdosis der unterschiedlichen lebensmittelrelevanten Infektionserreger bedingt eine Nulltoleranz derartiger Mikroorganismen in verzehrfertigen Lebensmitteln und somit die Notwendigkeit einer Kultivierung mittels unterschiedlicher Anreicherungsmethoden vor dem Einsatz molekularer Nachweisverfahren, wie z. B. PCR und Real-Time-PCR. Nach den derzeitigen gesetzlichen Vorgaben ist zusätzlich zu dem molekularbiologischen Nachweis von Infektions- und Intoxikationserregern in der Lebensmittelanalytik der kulturelle Keimnachweis zwingend notwendig. Molekulare Nachweisverfahren können somit entweder als Screeningmethoden für einen schnellen und hohen Probendurchsatz oder nach entsprechenden Kultivierungsschritten zur Bestätigung bestimmter genetischer Eigenschaften von Isolaten herangezogen werden [12].

  12. Features of vestibuloocular reflex modulations induced by altered gravitational forces in tadpoles ( Xenopus laevis)

    NASA Astrophysics Data System (ADS)

    Sebastian, C.; Horn, E.

    2001-01-01

    In Xenopus laevis tadpoles, we studied the static vestibuloocular reflex (rVOR) in relation to modifications of the gravitational environment to find basic mechanisms of how altered gravitational forces (AGF) affect this reflex. Animals were exposed to microgravity during space flight or hypergravity (3g) for 4 to 12 days. Basic observations were that (1) the development of the rVOR is significantly affected by altered gravitational conditions, (2) the duration of 1g-readaptation depends on the strength of the test stimulus, (3) μg induces malformations of the body which are related to the rVOR depression. Future studies are based on the hypotheses (1) that the vestibular nuclei play a key roll in the adaptation to AGF conditions, (2) that the stimulus transducing systems in the sense organ are affected by AGF conditions, and (3) that fertilized eggs will be converted to normal adults guided by physiological and morphological set points representing the genetic programs. Developmental retardation or acceleration, or otherwise occurring deviations from standard development during embryonic and postembryonic life will activate genes that direct the developmental processes towards normality.

  13. An internal model of head kinematics predicts the influence of head orientation on reflexive eye movements

    NASA Astrophysics Data System (ADS)

    Zupan, L. H.; Merfeld, D. M.

    2005-09-01

    Our sense of self-motion and self-orientation results from combining information from different sources. We hypothesize that the central nervous system (CNS) uses internal models of the laws of physics to merge cues provided by different sensory systems. Different models that include internal models have been proposed; we focus herein on that referred to as the sensory weighting model (Zupan et al 2002 Biol. Cybern. 86 209-30). For simplicity, we isolate the portion of the sensory weighting model that estimates head angular velocity: it includes an inverse internal model of head kinematics and an 'idiotropic' vector aligned with the main body axis. Following a post-rotatory tilt in the dark, which is a rapid tilt following a constant-velocity rotation about an earth-vertical axis, the inverse internal model is applied to conflicting vestibular signals. Consequently, the CNS computes an inaccurate estimate of head angular velocity that shifts toward alignment with an estimate of gravity. Since reflexive eye movements known as vestibulo-ocular reflexes (VOR) compensate for this estimate of head angular velocity, the model predicts that the VOR rotation axis shifts toward alignment with this estimate of gravity and that the VOR time constant depends on final head orientation. These predictions are consistent with experimental data.

  14. Connecting ears to eye muscles: evolution of a 'simple' reflex arc.

    PubMed

    Straka, Hans; Fritzsch, Bernd; Glover, Joel C

    2014-01-01

    Developmental and evolutionary data from vertebrates are beginning to elucidate the origin of the sensorimotor pathway that links gravity and motion detection to image-stabilizing eye movements--the vestibulo-ocular reflex (VOR). Conserved transcription factors coordinate the development of the vertebrate ear into three functional sensory compartments (graviception/translational linear acceleration, angular acceleration and sound perception). These sensory components connect to specific populations of vestibular and auditory projection neurons in the dorsal hindbrain through undetermined molecular mechanisms. In contrast, a molecular basis for the patterning of the vestibular projection neurons is beginning to emerge. These are organized through the actions of rostrocaudally and dorsoventrally restricted transcription factors into a 'hodological mosaic' within which coherent and largely segregated subgroups are specified to project to different targets in the spinal cord and brain stem. A specific set of these regionally diverse vestibular projection neurons functions as the central element that transforms vestibular sensory signals generated by active and passive head and body movements into motor output through the extraocular muscles. The large dynamic range of motion-related sensory signals requires an organization of VOR pathways as parallel, frequency-tuned, hierarchical connections from the sensory periphery to the motor output. We suggest that eyes, ears and functional connections subserving the VOR are vertebrate novelties that evolved into a functionally coherent motor control system in an almost stereotypic organization across vertebrate taxa. PMID:24776996

  15. Next Generation Life Support Project Status

    NASA Technical Reports Server (NTRS)

    Barta, Daniel J.; Chullen, Cinda; Pickering, Karen D.; Cox, Marlon; Towsend, Neil; Campbell, Colin; Flynn, Michael; Wheeler, Raymond

    2012-01-01

    Next Generation Life Support (NGLS) is one of several technology development projects sponsored by NASA s Game Changing Development Program. The NGLS Project is developing life support technologies (including water recovery and space suit life support technologies) needed for humans to live and work productively in space. NGLS has three project tasks: Variable Oxygen Regulator (VOR), Rapid Cycle Amine (RCA) swing bed, and Alternative Water Processor (AWP). The RCA swing bed and VOR tasks are directed at key technology needs for the Portable Life Support System (PLSS) for an Advanced Extravehicular Mobility Unit, with focus on test article development and integrated testing in an Advanced PLSS in cooperation with the Advanced Extra Vehicular Activity (EVA) Project. An RCA swing-bed provides integrated carbon dioxide removal and humidity control that can be regenerated in real time during an EVA. The VOR technology will significantly increase the number of pressure settings available to the space suit. Current space suit pressure regulators are limited to only two settings whereas the adjustability of the advanced regulator will be nearly continuous. The AWP effort, based on natural biological processes and membrane-based secondary treatment, will result in the development of a system capable of recycling wastewater from sources expected in future exploration missions, including hygiene and laundry water. This paper will provide a status of technology development activities and future plans.

  16. Inertial processing of vestibulo-ocular signals

    NASA Technical Reports Server (NTRS)

    Hess, B. J.; Angelaki, D. E.

    1999-01-01

    New evidence for a central resolution of gravito-inertial signals has been recently obtained by analyzing the properties of the vestibulo-ocular reflex (VOR) in response to combined lateral translations and roll tilts of the head. It is found that the VOR generates robust compensatory horizontal eye movements independent of whether or not the interaural translatory acceleration component is canceled out by a gravitational acceleration component due to simultaneous roll-tilt. This response property of the VOR depends on functional semicircular canals, suggesting that the brain uses both otolith and semicircular canal signals to estimate head motion relative to inertial space. Vestibular information about dynamic head attitude relative to gravity is the basis for computing head (and body) angular velocity relative to inertial space. Available evidence suggests that the inertial vestibular system controls both head attitude and velocity with respect to a gravity-centered reference frame. The basic computational principles underlying the inertial processing of otolith and semicircular canal afferent signals are outlined.

  17. A combination approach to treating fungal infections

    PubMed Central

    Shrestha, Sanjib K.; Fosso, Marina Y.; Garneau-Tsodikova, Sylvie

    2015-01-01

    Azoles are antifungal drugs used to treat fungal infections such as candidiasis in humans. Their extensive use has led to the emergence of drug resistance, complicating antifungal therapy for yeast infections in critically ill patients. Combination therapy has become popular in clinical practice as a potential strategy to fight resistant fungal isolates. Recently, amphiphilic tobramycin analogues, C12 and C14, were shown to display antifungal activities. Herein, the antifungal synergy of C12 and C14 with four azoles, fluconazole (FLC), itraconazole (ITC), posaconazole (POS), and voriconazole (VOR), was examined against seven Candida albicans strains. All tested strains were synergistically inhibited by C12 when combined with azoles, with the exception of C. albicans 64124 and MYA-2876 by FLC and VOR. Likewise, when combined with POS and ITC, C14 exhibited synergistic growth inhibition of all C. albicans strains, except C. albicans MYA-2876 by ITC. The combinations of FLC-C14 and VOR-C14 showed synergistic antifungal effect against three C. albicans and four C. albicans strains, respectively. Finally, synergism between C12/C14 and POS were confirmed by time-kill and disk diffusion assays. These results suggest the possibility of combining C12 or C14 with azoles to treat invasive fungal infections at lower administration doses or with a higher efficiency. PMID:26594050

  18. Destruction of Alicyclobacillus acidoterrestris spores in apple juice on stainless steel surfaces by chemical disinfectants.

    PubMed

    Podolak, Richard; Elliott, Philip H; Taylor, Bradley J; Khurana, Aakash; Black, Darryl G

    2009-03-01

    A study was conducted to determine the effects of three commercially available disinfectants on the reduction of Alicyclobacillus acidoterrestris spores in single-strength apple juice applied to stainless steel surfaces. Apple juice was inoculated with A. acidoterrestris spores, spread onto the surface of stainless steel chips (SSC), dried to obtain spore concentrations of approximately 10(4) CFU/cm2, and treated with disinfectants at temperatures ranging from 40 to 90 degrees C. The concentrations of disinfectants were 200, 500, 1,000, and 2,000 ppm of total chlorine for Clorox (CL) (sodium hypochlorite); 50, 100, and 200 ppm of total chlorine for Carnebon 200 (stabilized chlorine dioxide); and 1,500, 2,000, and 2,600 ppm for Vortexx (VOR) (hydrogen peroxide, peroxyacetic acid, and octanoic acid). For all temperatures tested, VOR at 2,600 ppm (90 degrees C) and CL at 2,000 ppm (90 degrees C) were the most inhibitory against A. acidoterrestris spores, resulting in 2.55- and 2.32-log CFU/cm2 reductions, respectively, after 2 min. All disinfectants and conditions tested resulted in the inactivation of A. acidoterrestris spores, with a maximum reduction of > 2 log CFU/cm2. Results from this study indicate that A. acidoterrestris spores, in single-strength apple juice, may be effectively reduced on stainless steel surface by VOR and CL, which may have practical applications in the juice industry. PMID:19343938

  19. Voriconazole treatment of Candida tropicalis meningitis: persistence of (1,3)-β-d-glucan in the cerebrospinal fluid is a marker of clinical and microbiological failure

    PubMed Central

    Ceccarelli, Giancarlo; Ghezzi, Maria Cristina; Raponi, Giammarco; Brunetti, Grazia; Marsiglia, Carolina; Fallani, Stefania; Novelli, Andrea; Venditti, Mario

    2016-01-01

    Abstract Introduction: Infections are still the most common complications of cerebral shunt procedures. Even though fungal etiologies are considered to be rare, they are associated with significant morbidity and mortality. Due to their uncommonness, diagnostic procedures and optimal therapy are poorly defined. We report a case of Candida tropicalis infection of ventriculo-peritoneal cerebrospinal fluid (CSF) shunt in a 49-year-old immune competent male treated with voriconazole (VOR). Methods: Microbiological and CSF markers (1,3-b-D-glucan-BDG) of fungal infection, biofilm production capacity, sensitivity of serial isolates of the pathogen, and the concentration of the antifungal drug have been monitored and related to the clinical course of this infection. Results: Despite appropriate treatment with VOR, in terms of adequate achieved CSF drug concentrations and initial effective therapeutic response, loss of VOR susceptibility of the C tropicalis and treatment failure were observed. Conclusion: Biofilm production of the C. tropicalis isolate might have had a significant role in treatment failure. Of interest, clinical and microbiological unfavorable outcome was anticipated by persistence of BDG in CSF. Rising titers of this marker were associated with relapse of fungal infection. PMID:27495087

  20. LTD, RP, and Motor Learning.

    PubMed

    Hirano, Tomoo; Yamazaki, Yoshito; Nakamura, Yoji

    2016-02-01

    Long-term depression (LTD) at excitatory synapses between parallel fibers and a Purkinje cell has been regarded as a critical cellular mechanism for motor learning. However, it was demonstrated that normal motor learning occurs under LTD suppression, suggesting that cerebellar plasticity mechanisms other than LTD also contribute to motor learning. One candidate for such plasticity is rebound potentiation (RP), which is long-term potentiation at inhibitory synapses between a stellate cell and a Purkinje cell. Both LTD and RP are induced by the increase in postsynaptic Ca(2+) concentration, and work to suppress the activity of a Purkinje cell. Thus, LTD and RP might work synergistically, and one might compensate defects of the other. RP induction is dependent on the interaction between GABAA receptor and GABAA receptor binding protein (GABARAP). Transgenic mice expressing a peptide which inhibits binding of GABARAP and GABAA receptor only in Purkinje cells show defects in both RP and adaptation of vestibulo-ocular reflex (VOR), a motor learning paradigm. However, another example of motor learning, adaptation of optokinetic response (OKR), is normal in the transgenic mice. Both VOR and OKR are reflex eye movements suppressing the slip of visual image on the retina during head movement. Previously, we reported that delphilin knockout mice show facilitated LTD induction and enhanced OKR adaptation, but we recently found that VOR adaptation was not enhanced in the knockout mice. These results together suggest that animals might use LTD and RP differently depending on motor learning tasks. PMID:26160222

  1. Alterations of the human vestibulo-ocular reflex in a simulated dive at 62 ATA.

    PubMed

    Gauthier, G M

    1976-06-01

    In an attempt to investigate some aspects of the high pressure nervous syndrome, the vestibulo-ocular reflex (VOR) gain was measured in two professional divers undergoing a simulated dive at 62 ATA. The aquanauts in a seated position were rotated sinusoidally around the vertical axis at a frequency of about 0.3 Hz over a 20 degrees range. Tests were performed at regular intervals prior to, during, and after the compression/decompression period. The rotations were applied either in total darkness or with a visual target rotating with the chair or with a target fixed to the chair-supporting frame. An infrared photoelectric system monitored eye movements. The results showed no spontaneous nystagmus, but two definite changes in VOR gain: (1) a slight but significant increase related to pressure increase, which may be due to an increase of the vestibular system excitability or a decrease of the cerebellar inhibition exerted upon the vestibular nuclei, and (2) an intermittently appearing increase (VOR gain between 1 and 1.3) during brief periods. The latter finding, not related to pressure, was interpreted as the expression of an underwater-adapted mode that may developed in professional divers submitted to the intensive use of magnifying diving-optical systems. PMID:951820

  2. An internal model of head kinematics predicts the influence of head orientation on reflexive eye movements.

    PubMed

    Zupan, L H; Merfeld, D M

    2005-09-01

    Our sense of self-motion and self-orientation results from combining information from different sources. We hypothesize that the central nervous system (CNS) uses internal models of the laws of physics to merge cues provided by different sensory systems. Different models that include internal models have been proposed; we focus herein on that referred to as the sensory weighting model. For simplicity, we isolate the portion of the sensory weighting model that estimates head angular velocity: it includes an inverse internal model of head kinematics and an 'idiotropic' vector aligned with the main body axis. Following a post-rotatory tilt in the dark, which is a rapid tilt following a constant-velocity rotation about an earth-vertical axis, the inverse internal model is applied to conflicting vestibular signals. Consequently, the CNS computes an inaccurate estimate of head angular velocity that shifts toward alignment with an estimate of gravity. Since reflexive eye movements known as vestibulo-ocular reflexes (VOR) compensate for this estimate of head angular velocity, the model predicts that the VOR rotation axis shifts toward alignment with this estimate of gravity and that the VOR time constant depends on final head orientation. These predictions are consistent with experimental data. PMID:16135883

  3. Preserved otolith organ function in caspase-3 deficient mice with impaired horizontal semicircular canal function

    PubMed Central

    Armstrong, Patrick A; Wood, Scott J; Shimizu, Naoki; Kuster, Kael; Perachio, Adrian; Makishima, Tomoko

    2015-01-01

    Genetically engineered mice are valuable models for elucidation of auditory and vestibular pathology. Our goal was to establish a comprehensive vestibular function testing system in mice using: 1) horizontal angular vestibular-ocular reflex (hVOR) to evaluate semicircular canal function, and 2) otolith-ocular reflex (OOR) to evaluate otolith organ function, and to validate the system by characterizing mice with vestibular dysfunction. We used pseudo-off vertical axis rotation (pOVAR) to induce an otolith-only stimulus using a custom-made centrifuge. For the OOR, horizontal slow phase eye velocity (HEV) and vertical eye position (VEP) was evaluated as a function of acceleration. Using this system, we characterized hVOR and OOR in the caspase-3 (Casp3) mutant mice. Casp3 −/− mice had severely impaired hVOR gain, while Casp3 +/− mice had an intermediate response compared to WT mice. Evaluation of OOR revealed that at low to mid frequencies and stimulus intensity, Casp3 mutants and WT mice had similar responses. At higher frequencies and stimulus intensity, the Casp3 mutants displayed mildly reduced otolith organ related responses. These findings suggest that the Casp3 gene is important for the proper function of the semicircular canals but less important for the otolith organ function. PMID:25827332

  4. Vestibuloocular reflex of rhesus monkeys after spaceflight

    NASA Technical Reports Server (NTRS)

    Cohen, Bernard; Kozlovskaia, Inessa; Raphan, Theodore; Solomon, David; Helwig, Denice; Cohen, Nathaniel; Sirota, Mikhail; Iakushin, Sergei

    1992-01-01

    The vestibuloocular reflex (VOR) of two rhesus monkeys was recorded before and after 14 days of spaceflight. The gain (eye velocity/head velocity) of the horizontal VOR, tested 15 and 18 h after landing, was approximately equal to preflight values. The dominant time constant of the animal tested 15 h after landing was equivalent to that before flight. During nystagmus induced by off-vertical axis rotation (OVAR), the latency, rising time constant, steady-state eye velocity, and phase of modulation in eye velocity and eye position with respect to head position were similar in both monkeys before and after flight. There were changes in the amplitude of modulation of horizontal eye velocity during steady-state OVAR and in the ability to discharge stored activity rapidly by tilting during postrotatory nystagmus (tilt dumping) after flight: OVAR modulations were larger, and tilt dumping was lost in the one animal tested on the day of landing and for several days thereafter. If the gain and time constant of the horizontal VOR exchange in microgravity, they must revert to normal soon after landing. The changes that were observed suggest that adaptation to microgravity had caused alterations in way that the central nervous system processes otolith input.

  5. Dissociation of locomotor and cerebellar deficits in a murine Angelman syndrome model.

    PubMed

    Bruinsma, Caroline F; Schonewille, Martijn; Gao, Zhenyu; Aronica, Eleonora M A; Judson, Matthew C; Philpot, Benjamin D; Hoebeek, Freek E; van Woerden, Geeske M; De Zeeuw, Chris I; Elgersma, Ype

    2015-11-01

    Angelman syndrome (AS) is a severe neurological disorder that is associated with prominent movement and balance impairments that are widely considered to be due to defects of cerebellar origin. Here, using the cerebellar-specific vestibulo-ocular reflex (VOR) paradigm, we determined that cerebellar function is only mildly impaired in the Ube3am-/p+ mouse model of AS. VOR phase-reversal learning was singularly impaired in these animals and correlated with reduced tonic inhibition between Golgi cells and granule cells. Purkinje cell physiology, in contrast, was normal in AS mice as shown by synaptic plasticity and spontaneous firing properties that resembled those of controls. Accordingly, neither VOR phase-reversal learning nor locomotion was impaired following selective deletion of Ube3a in Purkinje cells. However, genetic normalization of αCaMKII inhibitory phosphorylation fully rescued locomotor deficits despite failing to improve cerebellar learning in AS mice, suggesting extracerebellar circuit involvement in locomotor learning. We confirmed this hypothesis through cerebellum-specific reinstatement of Ube3a, which ameliorated cerebellar learning deficits but did not rescue locomotor deficits. This double dissociation of locomotion and cerebellar phenotypes strongly suggests that the locomotor deficits of AS mice do not arise from impaired cerebellar cortex function. Our results provide important insights into the etiology of the motor deficits associated with AS. PMID:26485287

  6. A combination approach to treating fungal infections.

    PubMed

    Shrestha, Sanjib K; Fosso, Marina Y; Garneau-Tsodikova, Sylvie

    2015-01-01

    Azoles are antifungal drugs used to treat fungal infections such as candidiasis in humans. Their extensive use has led to the emergence of drug resistance, complicating antifungal therapy for yeast infections in critically ill patients. Combination therapy has become popular in clinical practice as a potential strategy to fight resistant fungal isolates. Recently, amphiphilic tobramycin analogues, C12 and C14, were shown to display antifungal activities. Herein, the antifungal synergy of C12 and C14 with four azoles, fluconazole (FLC), itraconazole (ITC), posaconazole (POS), and voriconazole (VOR), was examined against seven Candida albicans strains. All tested strains were synergistically inhibited by C12 when combined with azoles, with the exception of C. albicans 64124 and MYA-2876 by FLC and VOR. Likewise, when combined with POS and ITC, C14 exhibited synergistic growth inhibition of all C. albicans strains, except C. albicans MYA-2876 by ITC. The combinations of FLC-C14 and VOR-C14 showed synergistic antifungal effect against three C. albicans and four C. albicans strains, respectively. Finally, synergism between C12/C14 and POS were confirmed by time-kill and disk diffusion assays. These results suggest the possibility of combining C12 or C14 with azoles to treat invasive fungal infections at lower administration doses or with a higher efficiency. PMID:26594050

  7. Resolution of sensory ambiguities for gaze stabilization requires a second neural integrator

    NASA Technical Reports Server (NTRS)

    Green, Andrea M.; Angelaki, Dora E.

    2003-01-01

    The ability to simultaneously move in the world and maintain stable visual perception depends critically on the contribution of vestibulo-ocular reflexes (VORs) to gaze stabilization. It is traditionally believed that semicircular canal signals drive compensatory responses to rotational head disturbances (rotational VOR), whereas otolith signals compensate for translational movements [translational VOR (TVOR)]. However, a sensory ambiguity exists because otolith afferents are activated similarly during head translations and reorientations relative to gravity (i.e., tilts). Extra-otolith cues are, therefore, necessary to ensure that dynamic head tilts do not elicit a TVOR. To investigate how extra-otolith signals contribute, we characterized the temporal and viewing distance-dependent properties of a TVOR elicited in the absence of a lateral acceleration stimulus to the otoliths during combined translational/rotational motion. We show that, in addition to otolith signals, angular head position signals derived by integrating sensory canal information drive the TVOR. A physiological basis for these results is proposed in a model with two distinct integration steps. Upstream of the well known oculomotor velocity-to-position neural integrator, the model incorporates a separate integration element that could represent the "velocity storage integrator," whose functional role in the oculomotor system has so far remained controversial. We propose that a key functional purpose of the velocity storage network is to temporally integrate semicircular canal signals, so that they may be used to extract translation information from ambiguous otolith afferent signals in the natural and functionally relevant bandwidth of head movements.

  8. Evaluation of the Effects of Ketoconazole and Voriconazole on the Pharmacokinetics of Oxcarbazepine and Its Main Metabolite MHD in Rats by UPLC-MS-MS.

    PubMed

    Chen, Xinxin; Gu, Ermin; Wang, Shuanghu; Zheng, Xiang; Chen, Mengchun; Wang, Li; Hu, Guoxin; Cai, Jian-ping; Zhou, Hongyu

    2016-03-01

    Oxcarbazepine (OXC), a second-generation antiepileptic drug, undergoes rapid reduction with formation of the active metabolite 10,11-dihydro-10-hydroxy-carbazepine (MHD) in vivo. In this study, a method for simultaneous determination of OXC and MHD in rat plasma using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS-MS) was developed and validated. Under given chromatographic conditions, OXC, MHD and internal standard diazepam were separated well and quantified by electrospray positive ionization mass spectrometry in the multiple reaction monitoring transitions mode. The method validation demonstrated good linearity over the range of 10-2,000 ng/mL for OXC and 5-1,000 ng/mL for MHD. The lower limit of quantification was 5 ng/mL for OXC and 2.5 ng/mL for MHD, respectively. The method was successfully applied to the evaluation of the pharmacokinetics of OXC and MHD in rats, with or without pretreatment by ketoconazole (KET) and voriconazole (VOR). Statistics indicated that KET and VOR significantly affected the disposition of OXC and MHD in vivo, whereas VOR predominantly interfered with the disposition of MHD. This method is suitable for pharmacokinetic study in small animals. PMID:26499119

  9. Dual adaptation and adaptive generalization of the human vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Welch, R. B.; Bridgeman, B.; Williams, J. A.; Semmler, R.

    1998-01-01

    In two experiments, we examined the possibility that the human vestibulo-ocular reflex (VOR) is subject to dual adaptation (the ability to adapt to a sensory rearrangement more rapidly and/or more completely after repeated experience with it) and adaptive generalization (the ability to adapt more readily to a novel sensory rearrangement as a result of prior dual adaptation training). In Experiment 1, the subjects actively turned the head during alternating exposure to a visual-vestibular rearrangement (target/head gain = 0.5) and the normal situation (target/head gain = 0.0). These conditions produced both adaptation and dual adaptation of the VOR but no evidence of adaptive generalization when tested with a target/head gain of 1.0. Experiment 2, in which exposure to the 0.5 gain entailed externally controlled (i.e., passive) whole body rotation, resulted in VOR adaptation but no dual adaptation. As in Experiment 1, no evidence of adaptive generalization was found.

  10. The statistical uncertainty of changes in winter storms over the North Atlantic and Europe in an ensemble of transient climate simulations

    NASA Astrophysics Data System (ADS)

    Della-Marta, Paul M.; Pinto, Joaquim G.

    2010-05-01

    Winter storms are among the most important natural hazards affecting Europe. We quantify changes in storm frequency and intensity over the North Atlantic and Europe under future climate scenarios in terms of return periods (RP) considering uncertainties due to both sampling and methodology. With this aim, ensemble simulations with the coupled ECHAM5/MPI-OM1 GCM for recent climate conditions (20C, 1960-2000) and future climate scenarios (SRES A1B and A2, 2001-2100) are analyzed. RPs of North Atlantic storms' minimum central pressure (CP) and maximum vorticity (VOR) remain unchanged by 2100 for both the A1B and A2 SRES scenarios compared to the recent climate (1960-2000). Whereas shortened RPs for VOR of all intensities are detected for the area between British Isles/North-Sea/western Europe as early as 2040. CP RP of future storms in this area are significant shorter only for lower intensity events. These results indicate that storms could become more intense during the 21st century. However, the changes in storm VOR RP may be unrealistically large: a present day 50 (20) year event becomes approximately a 9 (5.5) year event in both A1B and A2 scenarios by 2100. The detected shortened RPs of storms implies a higher risk of occurrence of damaging wind events over Europe.

  11. 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.

  12. The human vestibulo-ocular reflex during linear locomotion

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    During locomotion, there is a translation and compensatory rotation of the head in both the vertical and horizontal planes. During moderate to fast walking (100 m/min), vertical head translation occurs at the frequency of stepping (2 Hz) and generates peak linear acceleration of 0.37 g. Lateral head translation occurs at the stride frequency (1 Hz) and generates peak linear acceleration of 0.1 g. Peak head pitch and yaw angular velocities are approximately 17 degrees/s. The frequency and magnitude of these head movements are within the operational range of both the linear and angular vestibulo-ocular reflex (IVOR and aVOR). Vertical eye movements undergo a phase reversal from near to far targets. When viewing a far (>1 m) target, vertical eye velocity is typical of an aVOR response; that is, it is compensatory for head pitch. At close viewing distances (<1 m), vertical eye velocity is in phase with head pitch and is compensatory for vertical head translation, suggesting that the IVOR predominantly generates the eye movement response. Horizontal head movements during locomotion occur at the stride frequency of 1 Hz, where the IVOR gain is low. Horizontal eye movements are compensatory for head yaw at all viewing distances and are likely generated by the aVOR.

  13. 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.

  14. Primate translational vestibuloocular reflexes. I. High-frequency dynamics and three-dimensional properties during lateral motion

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; McHenry, M. Q.; Hess, B. J.

    2000-01-01

    The dynamics and three-dimensional (3-D) properties of the primate translational vestibuloocular reflex (trVOR) for high-frequency (4-12 Hz, +/-0.3-0.4 g) lateral motion were investigated during near-target viewing at center and eccentric targets. Horizontal response gains increased with frequency and depended on target eccentricity. The larger the horizontal and vertical target eccentricity, the steeper the dependence of horizontal response gain on frequency. In addition to horizontal eye movements, robust torsional response components also were present at all frequencies. During center-target fixation, torsional response phase was opposite (anticompensatory) to that expected for an "apparent" tilt response. Instead torsional response components depended systematically on vertical-target eccentricity, increasing in amplitude when looking down and reversing phase when looking up. As a result the trVOR eye velocity vector systematically tilted away from a purely horizontal direction, through an angle that increased with vertical eccentricity with a slope of approximately 0.7. This systematic dependence of torsional eye velocity tilt on vertical eye position suggests that the trVOR might follow the 3-D kinematic requirements that have been shown to govern visually guided eye movements and near-target fixation.

  15. Adaptive modification of vestibularly perceived rotation.

    PubMed

    Bloomberg, J; Melvill Jones, G; Segal, B

    1991-01-01

    Results from Bloomberg et al. (1991) led to the hypothesis that saccades which accompany the dark-tested vestibulo-ocular reflex (VOR) tend to move the eyes towards a vestibularly derived percept of an intended oculomotor goal: also that this is so even when that percept has been adaptively modified by suitably prolonged visual-vestibular conflict. The present experiments investigate these implications by comparing the combined VOR + saccade performance with a presumed "motor readout" of the normal and adaptively modified vestibular percept. The methods employed were similar to those of an earlier study Bloomberg et al. (1988) in which it was found that after cessation of a brief passive whole body rotation in the dark, a previously seen earth-fixed target can be accurately located by saccadic eye movements based on a vestibular memory of the preceding head rotation; the so-called "Vestibular Memory-Contingent Saccade" (VMCS) paradigm. The results showed that the vestibular perceptual response, as measured after rotation by means of the VMCS paradigm, was on average indistinguishable from the combined VOR + saccade response measured during rotation. Furthermore, this was so in both the normal and adapted states. We conclude that these findings substantiate the above hypothesis. The results incidentally reaffirm the adaptive modifiability of vestibular perception, emphasing the need for active maintenance of its proper calibration according to behavioural context. PMID:1855564

  16. Thoracic cavity segmentation algorithm using multiorgan extraction and surface fitting in volumetric CT

    SciTech Connect

    Bae, JangPyo; Kim, Namkug Lee, Sang Min; Seo, Joon Beom; Kim, Hee Chan

    2014-04-15

    Purpose: To develop and validate a semiautomatic segmentation method for thoracic cavity volumetry and mediastinum fat quantification of patients with chronic obstructive pulmonary disease. Methods: The thoracic cavity region was separated by segmenting multiorgans, namely, the rib, lung, heart, and diaphragm. To encompass various lung disease-induced variations, the inner thoracic wall and diaphragm were modeled by using a three-dimensional surface-fitting method. To improve the accuracy of the diaphragm surface model, the heart and its surrounding tissue were segmented by a two-stage level set method using a shape prior. To assess the accuracy of the proposed algorithm, the algorithm results of 50 patients were compared to the manual segmentation results of two experts with more than 5 years of experience (these manual results were confirmed by an expert thoracic radiologist). The proposed method was also compared to three state-of-the-art segmentation methods. The metrics used to evaluate segmentation accuracy were volumetric overlap ratio (VOR), false positive ratio on VOR (FPRV), false negative ratio on VOR (FNRV), average symmetric absolute surface distance (ASASD), average symmetric squared surface distance (ASSSD), and maximum symmetric surface distance (MSSD). Results: In terms of thoracic cavity volumetry, the mean ± SD VOR, FPRV, and FNRV of the proposed method were (98.17 ± 0.84)%, (0.49 ± 0.23)%, and (1.34 ± 0.83)%, respectively. The ASASD, ASSSD, and MSSD for the thoracic wall were 0.28 ± 0.12, 1.28 ± 0.53, and 23.91 ± 7.64 mm, respectively. The ASASD, ASSSD, and MSSD for the diaphragm surface were 1.73 ± 0.91, 3.92 ± 1.68, and 27.80 ± 10.63 mm, respectively. The proposed method performed significantly better than the other three methods in terms of VOR, ASASD, and ASSSD. Conclusions: The proposed semiautomatic thoracic cavity segmentation method, which extracts multiple organs (namely, the rib, thoracic wall, diaphragm, and heart

  17. Suppression of the human vestibulo-ocular reflex by visual fixation or forced convergence in the dark, with a model interpretation.

    PubMed

    Gizzi, Martin S; Harper, Harry Wms

    2003-05-01

    Six normal humans experienced yaw axis steps of velocity at 120 degrees /s in the dark. During the post-rotary period, subjects either had a null-task (do nothing); an ocular motor task (forced convergence: crossing the eyes); or a visual task (fixating a head-stationary target against a background of 10 degrees light/dark bars). Tasks started at 3 s post-rotation, and lasted either 2, 5, 10, or 15 s. Ocular motor and visual tasks were tested on different days. Five repetitions of each task duration were recorded for each subject. A mean VOR gain of 0.52 was observed, which did not vary with experimental conditions. Both convergence and fixation markedly suppressed nystagmus; in fact, the VORs obtained with the two different tasks are superficially similar in appearance. However, mean null-task time-constants were 9.4 s for convergence days, but 8.4 s for fixation days, and there was a small but significant reduction in overall null-task VOR amplitude on fixation days. Also, post-convergence slow-phase velocities were slightly enhanced, while post-fixation velocities were significantly reduced. The time-constant of velocity storage was found to be 10.1 s for convergence responses and 8.2 s for fixation responses. These differences can be understood in terms of modifications in central velocity storage during visual fixation which do not occur with convergence. The mean fixation data were analyzed in the context of a VOR model well-established for monkey data. With appropriate choice of parameters, this model accurately reproduces most features of the human data. An estimate for the human cupula time-constant of 3.3 s is obtained. Compared with the monkey, fixation suppression is greater and post-fixation velocity reduction less. Retinal slip alone accounts well for this; "velocity dumping" by an integrator shunt must be slight if present at all. The model correctly represents the post-fixation VOR for all durations of fixation. PMID:12854056

  18. Opioid-Induced Nausea Involves a Vestibular Problem Preventable by Head-Rest

    PubMed Central

    Sağlam, Murat; Schulz, Christian M.; Wagner, Klaus J.; Taki, Masakatsu; Kochs, Eberhard F.; Jahn, Klaus; Brandt, Thomas; Glasauer, Stefan; Schneider, Erich

    2015-01-01

    Background and Aims Opioids are indispensable for pain treatment but may cause serious nausea and vomiting. The mechanism leading to these complications is not clear. We investigated whether an opioid effect on the vestibular system resulting in corrupt head motion sensation is causative and, consequently, whether head-rest prevents nausea. Methods Thirty-six healthy men (26.6±4.3 years) received an opioid remifentanil infusion (45 min, 0.15 μg/kg/min). Outcome measures were the vestibulo-ocular reflex (VOR) gain determined by video-head-impulse-testing, and nausea. The first experiment (n = 10) assessed outcome measures at rest and after a series of five 1-Hz forward and backward head-trunk movements during one-time remifentanil administration. The second experiment (n = 10) determined outcome measures on two days in a controlled crossover design: (1) without movement and (2) with a series of five 1-Hz forward and backward head-trunk bends 30 min after remifentanil start. Nausea was psychophysically quantified (scale from 0 to 10). The third controlled crossover experiment (n = 16) assessed nausea (1) without movement and (2) with head movement; isolated head movements consisting of the three axes of rotation (pitch, roll, yaw) were imposed 20 times at a frequency of 1 Hz in a random, unpredictable order of each of the three axes. All movements were applied manually, passively with amplitudes of about ± 45 degrees. Results The VOR gain decreased during remifentanil administration (p<0.001), averaging 0.92±0.05 (mean±standard deviation) before, 0.60±0.12 with, and 0.91±0.05 after infusion. The average half-life of VOR recovery was 5.3±2.4 min. 32/36 subjects had no nausea at rest (nausea scale 0.00/0.00 median/interquartile range). Head-trunk and isolated head movement triggered nausea in 64% (p<0.01) with no difference between head-trunk and isolated head movements (nausea scale 4.00/7.25 and 1.00/4.5, respectively). Conclusions Remifentanil reversibly

  19. Transmastoid galvanic stimulation does not affect the vergence-mediated gain increase of the human angular vestibulo-ocular reflex

    PubMed Central

    Migliaccio, Americo A.; Della Santina, Charles C.; Carey, John P.

    2012-01-01

    Vergence is one of several viewing contexts that require an increase in the angular vestibular-ocular reflex (aVOR) response. A previous monkey study found that the vergence-mediated gain (eye/head velocity) increase of the aVOR was attenuated by 64% when anodic currents, which preferentially lower the activity of irregularly firing vestibular afferents, were delivered to both labyrinths. We sought to determine if there was similar evidence implicating a role for irregular afferents in the vergence-mediated gain increase of the human aVOR. Our study is based upon analysis of the aVOR evoked by head rotations, delivered passively while subjects viewed a near (15cm) or far (124cm) target and applying galvanic vestibular stimulation (GVS) via surface electrodes. We tested 12 subjects during 2–3 sessions each. Vestibular stimuli consisted of passive whole-body rotations (sinusoids from 0.05 – 3Hz and 12 – 25°/s, and transients with peak ~15°, 50°/s, 500°/s2) and head-on-body impulses (peak ~30°, 150°/s, 3000°/s2). GVS was on for 10s every 20s. All polarity combinations were tested, with emphasis on uni- and bi-lateral anodic inhibition. The average stimulus current was 5.9 ± 1.6 mA (range: 3 – 9.5 mA), vergence angle (during near-viewing) was 22.6 ± 2.8° and slow phase eye velocity caused by left anodic current stimulation with head stationary was −3.4 ± 1.1°/s, −0.2 ± 0.6°/s and 2.5 ± 1.4°/s (torsion, vertical, horizontal). No statistically significant GVS effects were observed, suggesting that surface electrode GVS has no effect on the vergence-mediated gain increase of the aVOR at the current levels (~6 mA) tolerated by most humans. We conclude that clinically practical transmastoid GVS does not effectively silence irregular afferents and hypothesize that currents > 10mA are needed to reproduce the monkey results. PMID:23150093

  20. Constraints of subducted slab geometries on trench migration and subduction velocities: flat slabs and slab curtains in the mantle under Asia

    NASA Astrophysics Data System (ADS)

    Wu, J. E.; Suppe, J.; Renqi, L.; Lin, C.; Kanda, R. V.

    2013-12-01

    The past locations, shapes and polarity of subduction trenches provide first-order constraints for plate tectonic reconstructions. Analogue and numerical models of subduction zones suggest that relative subducting (Vs) and overriding (Vor) plate velocities may strongly influence final subducted slab geometries. Here we have mapped the 3D geometries of subducted slabs in the upper and lower mantle of Asia from global seismic tomography. We have incorporated these slabs into plate tectonic models, which allows us to infer the subducting and overriding plate velocities. We describe two distinct slab geometry styles, ';flat slabs' and ';slab curtains', and show their implications for paleo-trench positions and subduction geometries in plate tectonic reconstructions. When compared to analogue and numerical models, the mapped slab styles show similarities to modeled slabs that occupy very different locations within Vs:Vor parameter space. ';Flat slabs' include large swaths of sub-horizontal slabs in the lower mantle that underlie the well-known northward paths of India and Australia from Eastern Gondwana, viewed in a moving hotspot reference. At India the flat slabs account for a significant proportion of the predicted lost Ceno-Tethys Ocean since ~100 Ma, whereas at Australia they record the existence of a major 8000km by 2500-3000km ocean that existed at ~43 Ma between East Asia, the Pacific and Australia. Plate reconstructions incorporating the slab constraints imply these flat slab geometries were generated when continent overran oceanic lithosphere to produce rapid trench retreat, or in other words, when subducting and overriding velocities were equal (i.e. Vs ~ Vor). ';Slab curtains' include subvertical Pacific slabs near the Izu-Bonin and Marianas trenches that extend from the surface down to 1500 km in the lower mantle and are 400 to 500 km thick. Reconstructed slab lengths were assessed from tomographic volumes calculated at serial cross-sections. The ';slab

  1. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. II. Responses after canal plugging

    NASA Technical Reports Server (NTRS)

    Lasker, D. M.; Backous, D. D.; Lysakowski, A.; Davis, G. L.; Minor, L. B.

    1999-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in four squirrel monkeys after unilateral plugging of the three semicircular canals. During the period (1-4 days) that animals were kept in darkness after plugging, the gain during steps of acceleration (3, 000 degrees /s(2), peak velocity = 150 degrees /s) was 0.61 +/- 0.14 (mean +/- SD) for contralesional rotations and 0.33 +/- 0.03 for ipsilesional rotations. Within 18-24 h after animals were returned to light, the VOR gain for contralesional rotations increased to 0. 88 +/- 0.05, whereas there was only a slight increase in the gain for ipsilesional rotations to 0.37 +/- 0.07. A symmetrical increase in the gain measured at the plateau of head velocity was noted after animals were returned to light. The latency of the VOR was 8.2 +/- 0. 4 ms for ipsilesional and 7.1 +/- 0.3 ms for contralesional rotations. The VOR evoked by sinusoidal rotations of 0.5-15 Hz, +/-20 degrees /s had no significant half-cycle asymmetries. The recovery of gain for these responses after plugging was greater at lower than at higher frequencies. Responses to rotations at higher velocities for frequencies >/=4 Hz showed an increase in contralesional half-cycle gain, whereas ipsilesional half-cycle gain was unchanged. A residual response that appeared to be canal and not otolith mediated was noted after plugging of all six semicircular canals. This response increased with frequency to reach a gain of 0.23 +/- 0.03 at 15 Hz, resembling that predicted based on a reduction of the dominant time constant of the canal to 32 ms after plugging. A model incorporating linear and nonlinear pathways was used to simulate the data. The coefficients of this model were determined from data in animals with intact vestibular function. Selective increases in the gain for the linear and nonlinear pathways predicted the changes in recovery observed after canal plugging. An increase in gain of

  2. [Flexibility in the adaptation of the vestibulo-ocular reflex to modified visual inputs in humans].

    PubMed

    Hattori, K; Watanabe, S; Nakamura, T; Kato, I

    2000-10-01

    The vestibulo-ocular reflex (VOR) serves to stabilize images on the retina. To maintain appropriate performance and minimize image slippage throughout life, the VOR is subject to long-term adaptive regulation in response to visual input. Adaptive changes in VOR gain (eye velocity/head velocity) can be evoked either by fitting subjects with magnifying, miniaturizing, or reversing spectacles during normal behavior or by moving a large visual field in or out of phase relative to the subject's head movement. These changes exhibit frequency-selectivity. Here, we examine the flexibility of VOR gains by causing VOR in similar directions to undergo different behavioral gain changes. Nine healthy adults, ranging in age from 24 to 38 (mean 28.5) with no history of neurotological symptoms participated in the study. All subjects demonstrated clinically normal functioning on a screening battery of tests that included combined neurologic and otologic physical examinations. Horizontal and vertical eye positions were recorded by bitemporal DC coupled electrooculography (EOG). The subject sat in a rotating chair. The axis of rotation of the body was always earth-vertical, the interaural axis crossing the axis of rotation of the chair. The head was positioned at 20 degrees down in all experiments and was stabilized in this position using a chin rest. The chair was 78 cm in diameter and was shielded by a half-cylindrical optokinetic screen positioned in front of the subjects. Random dot patterns were projected onto this screen. During per- and post-adaptation periods, goggles were fitted to ensure that the subject was in complete darkness and the chair was rotated sinusoidally. The amplitude of the rotating chair was 30 degrees and 60 degrees. Frequencies of rotation were 0.1 Hz, 0.2 Hz, 0.3 Hz and 0.4 Hz for amplitudes of 30 degrees and 0.1 Hz, 0.2 Hz, and 0.3 Hz for amplitudes of 60 degrees. To induce VOR adaptation, the retinal slippage velocity caused by the visual input of a

  3. Horizontal vestibulo-ocular reflex and head stability in response to torso perturbations during visual search.

    PubMed

    Crane, B T; Demer, J L

    1999-04-01

    Eye, head, and torso movements were recorded using magnetic search coils while six normal human subjects made unconstrained eye and head movements as they searched for targets in a panoramic visual environment. Torso movements were imposed by pseudorandom rotations of a servomotor-driver chair in which subjects were seated; body motion was partially transmitted to the head as a perturbation. Horizontal vestibulo-ocular reflex (VOR) gain (eye velocity divided by head velocity) and head gain (head velocity divided by torso velocity) were determined. Measurements were performed with unaided vision and while subjects wore x4 binocular telescopic spectacles. Since the head was free to move during the experiment, much of the perturbation delivered to the torso was compensated by head rotation on the neck. During the 50 ms immediately following chair rotation, the head corrected 98% of the torso motion. For the interval 50-80 ms after the perturbation 81-85% of the perturbation was corrected by head movement. The degree of head compensation did not significantly depend on magnification or type of visual target. The density distribution for VOR gain was calculated over the entire course of each trial and was found to be sharply centered between 0.9 and 1.0 for trials with unmagnified vision. The gain density distribution with x4 telescopes was broader and centered around 1.5, reflecting visual enhancement. Gain of the VOR was also determined during four discrete epochs covering the period from 50 ms before to 130 ms after the onset of each imposed torso rotation. The first, second, and fourth epochs were 50 ms each, while the third epoch was 30 ms. The torso began to rotate in the second epoch (0-50 ms), and the onset of head rotation was in the third epoch (50-80 ms). Gains of the VOR determined during the first three epochs were in response to self-generated head rotation and were not significantly different from each other, averaging 1.0+/-0.4 (n=1604, mean+/-SD) with

  4. Effects of spaceflight on ocular counterrolling and the spatial orientation of the vestibular system

    NASA Technical Reports Server (NTRS)

    Dai, M.; McGarvie, L.; Kozlovskaya, I.; Raphan, T.; Cohen, B.

    1994-01-01

    We recorded the horizontal (yaw), vertical (pitch), and torsional (roll) eye movements of two rhesus monkeys with scleral search coils before and after the COSMOS Biosatellite 2229 Flight. The aim was to determine effects of adaptation to microgravity on the vestibulo-ocular reflex (VOR). The animals flew for 11 days. The first postflight tests were 22 h and 55 h after landing, and testing extended for 11 days after reentry. There were four significant effects of spaceflight on functions related to spatial orientation: (1) Compensatory ocular counterrolling (OCR) was reduced by about 70% for static and dynamic head tilts with regard to gravity. The reduction in OCR persisted in the two animals throughout postflight testing. (2) The gain of the torsional component of the angular VOR (roll VOR) was decreased by 15% and 50% in the two animals over the same period. (3) An up-down asymmetry of nystagmus, present in the two monkeys before flight was reduced after exposure to microgravity. (4) The spatial orientation of velocity storage was shifted in the one monkey that could be tested soon after flight. Before flight, the yaw axis eigenvector of optokinetic afternystagmus was close to gravity when the animal was upright or tilted. After flight, the yaw orientation vector was shifted toward the body yaw axis. By 7 days after recovery, it had reverted to a gravitational orientation. We postulate that spaceflight causes changes in the vestibular system which reflect adaptation of spatial orientation from a gravitational to a body frame of reference. These changes are likely to play a role in the postural, locomotor, and gaze instability demonstrated on reentry after spaceflight.

  5. Oculomotor deficits in aryl hydrocarbon receptor null mouse.

    PubMed

    Chevallier, Aline; Mialot, Antoine; Petit, Jean-Maurice; Fernandez-Salguero, Pedro; Barouki, Robert; Coumoul, Xavier; Beraneck, Mathieu

    2013-01-01

    The Aryl hydrocarbon Receptor or AhR, a ligand-activated transcription factor, is known to mediate the toxic and carcinogenic effects of various environmental pollutants such as 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD). Recent studies in Caenorhabditis elegans and Drosophila melanogaster show that the orthologs of the AhR are expressed exclusively in certain types of neurons and are implicated in the development and the homeostasis of the central nervous system. While physiological roles of the AhR were demonstrated in the mammalian heart, liver and gametogenesis, its ontogenic expression and putative neural functions remain elusive. Here, we report that the constitutive absence of the AhR in adult mice (AhR-/-) leads to abnormal eye movements in the form of a spontaneous pendular horizontal nystagmus. To determine if the nystagmus is of vestibular, visual, or cerebellar origin, gaze stabilizing reflexes, namely vestibulo-ocular and optokinetic reflexes (VOR and OKR), were investigated. The OKR is less effective in the AhR-/- mice suggesting a deficit in the visuo-motor circuitry, while the VOR is mildly affected. Furthermore, the AhR is expressed in the retinal ganglion cells during the development, however electroretinograms revealed no impairment of retinal cell function. The structure of the cerebellum of the AhR-/- mice is normal which is compatible with the preserved VOR adaptation, a plastic process dependent on cerebellar integrity. Finally, intoxication with TCDD of control adults did not lead to any abnormality of the oculomotor control. These results demonstrate that the absence of the AhR leads to acquired central nervous system deficits in the adults. Given the many common features between both AhR mouse and human infantile nystagmus syndromes, the AhR-/- mice might give insights into the developmental mechanisms which lead to congenital eye disorders. PMID:23301081

  6. Novel antifungal drugs against fungal pathogens: do they provide promising results for treatment?

    PubMed

    Gedik, Habip; Şimşek, Funda; Yıldırmak, Taner; Kantürk, Arzu; Arıca, Deniz; Aydın, Demet; Demirel, Naciye; Yokuş, Osman

    2015-06-01

    The febrile neutropenia episodes of hematological patients and their outcomes were evaluated with respect to fungal pathogens and antifungal therapy in this retrospective study. All patients, who were older than 14 years of age and developed at least one neutropenic episode after chemotherapy due to hematological cancer from November 2010 to November 2012, were included into the study. We retrospectively collected demographic, treatment, and survival data of 126 patients with neutropenia and their 282 febrile episodes. The mean Multinational Association for Supportive Care in Cancer score was 17.18 ± 8.27. Systemic antifungal drugs were initiated in 22 patients with 30 culture-proven invasive fungal infections (IFIs), 25 attacks of 19 patients with probable invasive pulmonary aspergillosis (IPA), 42 attacks of 38 patients with possible IPA, and 31 attacks of 30 patients with suspected IFI. Voriconazole (VOR), caspofungin and liposomal amphotericin B were used to treat 72 episodes of 65 patients, 45 episodes of 37 patients and 34 episodes of 32 patients as a first-line therapy, respectively. Unfavorable conditions of our hematology ward are thought to increase the number of cases with invasive pulmonary aspergillosis and VOR use. It should be taken into consideration that increased systemic and per oral VOR usage predisposes patients to colonization and infection with azole-resistant fungal strains. Catheters should be removed in cases where patients' conditions are convenient to remove it. Acute myeloblastic leukemia cases that are more likely to develop invasive fungal infections should be monitored closely for early diagnosis and timely initiation of antifungal drugs which directly correlates with survival rates. PMID:25825558

  7. Artificial gravity—head movements during short-radius centrifugation: Influence of cognitive effects

    NASA Astrophysics Data System (ADS)

    Meliga, Philippe; Hecht, Heiko; Young, Laurence R.; Mast, Fred W.

    2005-05-01

    Short-radius centrifugation is a potential countermeasure against the effects of prolonged weightlessness. Head movements in a rotating environment, however, induce serious side effects: inappropriate vestibular ocular reflexes (VOR), body-tilt illusions and motion sickness induced by cross-coupled accelerations on a rotating platform. These are well predicted by a semicircular canal model. The present study investigates cognitive effects on the inappropriate VOR and the illusory sensations experienced by subjects rotating on a short-radius centrifuge (SRC). Subjects (N=19) were placed supine on a rotating horizontal bed with their head at the center of rotation. To investigate the extent to which they could control their sensations voluntarily, subjects were asked alternatively to "fight" (i.e. to try to resist and suppress) those sensations, or to "go" with (i.e. try to enhance or, at least, acquiesce in) them. The only significant effect on the VOR of this cognitive intervention was to diminish the time constant characterizing the decay of the nystagmus in subjects who had performed the "go" (rather than the "fight") trials. However, illusory sensations, as measured by reported subjective intensities, were significantly less intense during the "fight" than during the "go" trials. These measurements also verified an asymmetry in illusory sensation known from earlier experiments: the illusory sensations are greater when the head is rotated from right ear down (RED) to nose up (NU) posture than from NU to RED. The subjects habituated, modestly, to the rotation between their first and second sequences of trials, but showed no better (or worse) suppression of illusory sensations thereafter. No significant difference in habituation was observed between the "fight" and "go" trials.

  8. Investigations of the pathogenesis of acquired pendular nystagmus

    NASA Technical Reports Server (NTRS)

    Averbuch-Heller, L.; Zivotofsky, A. Z.; Das, V. E.; DiScenna, A. O.; Leigh, R. J.

    1995-01-01

    We investigated the pathogenesis of acquired pendular nystagmus (APN) in six patients, three of whom had multiple sclerosis. First, we tested the hypothesis that the oscillations of APN are due to a delay in visual feedback secondary, for example, to demyelination of the optic nerves. We manipulated the latency to onset of visually guided eye movements using an electronic technique that induces sinusoidal oscillations in normal subjects. This manipulation did not change the characteristics of the APN, but did superimpose lower-frequency oscillations similar to those induced in normal subjects. These results are consistent with current models for smooth (non-saccadic) eye movements, which predict that prolongation of visual feedback could not account for the high-frequency oscillations that often characterize APN. Secondly, we attempted to determine whether an increase in the gain of the visually-enhanced vestibulo-ocular reflex (VOR), produced by viewing a near target, was accompanied by a commensurate increase in the amplitude of APN. Increases in horizontal or vertical VOR gain during near viewing occurred in four patients, but only two of them showed a parallel increase in APN amplitude. On the other hand, APN amplitude decreased during viewing of the near target in the two patients who showed no change in VOR gain. Taken together, these data suggest that neither delayed visual feedback nor a disorder of central vestibular mechanisms is primarily responsible for APN. More likely, these ocular oscillations are produced by abnormalities of internal feedback circuits, such as the reciprocal connections between brainstem nuclei and cerebellum.

  9. Modification of the Cervico-ocular Reflex by Canal Plugging

    PubMed Central

    Yakushin, Sergei B.; Tarasenko, Yelena; Raphan, Theodore; Suzuki, Jun-Ichi; Della Santina, Charles C.; Minor, Lloyd B.; Cohen, Bernard

    2016-01-01

    The cervico-ocular reflex (COR) has a low gain in normal animals. In this study, we determined whether COR gain increases were specific to the low/midband frequency range, which is the range over which the angular vestibulo-ocular reflex (aVOR) is compromised by plugging. The gain and phase of the yaw and pitch COR and aVOR were compared in normal monkeys and those with all six semicircular canals or only the lateral canal plugged. During experiments animals sat with the body fixed to a chair and the head fixed in space. The body was oscillated about body-yaw and body-pitch axes over a frequency range of 0.05–6 Hz, with amplitude <10°. For normal animals, both yaw and pitch eye velocities were compensatory to the relative velocity of the head with respect to the body. The gains were 0.1–0.2 at frequencies below 1 Hz and decreased to zero as stimulus frequency increased above 1 Hz. Canal-plugged animals had COR gains close to 1.0 at low frequencies, decreasing to ≈0.6 at 0.5 Hz and to 0.2 for stimulus frequencies above 3 Hz. The phase of eye velocity was 180° relative to head-re-body velocity at frequencies below 0.5 Hz and shifted toward 270° as frequencies were increased to 4 Hz. This study demonstrates that adaptation of COR gain is tuned to a frequency range at which the aVOR is compromised by the canal plugging. PMID:19645881

  10. Prevalence of Vestibular Disorder in Older People Who Experience Dizziness

    PubMed Central

    Chau, Allan T.; Menant, Jasmine C.; Hübner, Patrick P.; Lord, Stephen R.; Migliaccio, Americo A.

    2015-01-01

    Dizziness and imbalance are clinically poorly defined terms, which affect ~30% of people over 65 years of age. In these people, it is often difficult to define the primary cause of dizziness, as it can stem from cardiovascular, vestibular, psychological, and neuromuscular causes. However, identification of the primary cause is vital in determining the most effective treatment strategy for a patient. Our aim is to accurately identify the prevalence of benign paroxysmal positional vertigo (BPPV), peripheral, and central vestibular hypofunction in people aged over 50 years who had experienced dizziness within the past year. Seventy-six participants aged 51–92 (mean ± SD = 69 ± 9.5 years) were tested using the head thrust dynamic visual acuity (htDVA) test, dizziness handicap inventory (DHI), as well as sinusoidal and unidirectional rotational chair testing, in order to obtain data for htDVA score, DHI score, sinusoidal (whole-body, 0.1–2 Hz with peak velocity at 30°/s) vestibulo-ocular reflex (VOR) gain and phase, transient (whole-body, acceleration at 150°/s2 to a constant velocity rotation of 50°/s) VOR gain and time constant (TC), optokinetic nystagmus (OKN) gain, and TC (whole-body, constant velocity rotation at 50°/s). We found that BPPV, peripheral and central vestibular hypofunction were present in 38 and 1% of participants, respectively, suggesting a likely vestibular cause of dizziness in these people. Of those with a likely vestibular cause, 63% had BPPV; a figure higher than previously reported in dizziness clinics of ~25%. Our results indicate that htDVA, sinusoidal (particularly 0.5–1 Hz), and transient VOR testing were the most effective at detecting people with BPPV or vestibular hypofunction, whereas DHI and OKN were effective at only detecting non-BPPV vestibular hypofunction. PMID:26733940

  11. Comparison of Predictable Smooth Ocular and Combined Eye-Head Tracking Behaviour in Patients with Lesions Affecting the Brainstem and Cerebellum

    NASA Technical Reports Server (NTRS)

    Grant, Michael P.; Leigh, R. John; Seidman, Scott H.; Riley, David E.; Hanna, Joseph P.

    1992-01-01

    We compared the ability of eight normal subjects and 15 patients with brainstem or cerebellar disease to follow a moving visual stimulus smoothly with either the eyes alone or with combined eye-head tracking. The visual stimulus was either a laser spot (horizontal and vertical planes) or a large rotating disc (torsional plane), which moved at one sinusoidal frequency for each subject. The visually enhanced Vestibulo-Ocular Reflex (VOR) was also measured in each plane. In the horizontal and vertical planes, we found that if tracking gain (gaze velocity/target velocity) for smooth pursuit was close to 1, the gain of combined eye-hand tracking was similar. If the tracking gain during smooth pursuit was less than about 0.7, combined eye-head tracking was usually superior. Most patients, irrespective of diagnosis, showed combined eye-head tracking that was superior to smooth pursuit; only two patients showed the converse. In the torsional plane, in which optokinetic responses were weak, combined eye-head tracking was much superior, and this was the case in both subjects and patients. We found that a linear model, in which an internal ocular tracking signal cancelled the VOR, could account for our findings in most normal subjects in the horizontal and vertical planes, but not in the torsional plane. The model failed to account for tracking behaviour in most patients in any plane, and suggested that the brain may use additional mechanisms to reduce the internal gain of the VOR during combined eye-head tracking. Our results confirm that certain patients who show impairment of smooth-pursuit eye movements preserve their ability to smoothly track a moving target with combined eye-head tracking.

  12. Progress toward development of a multichannel vestibular prosthesis for treatment of bilateral vestibular deficiency.

    PubMed

    Fridman, Gene Y; Della Santina, Charles C

    2012-11-01

    This article reviews vestibular pathology and the requirements and progress made in the design and construction of a vestibular prosthesis. Bilateral loss of vestibular sensation is disabling. When vestibular hair cells are injured by ototoxic medications or other insults to the labyrinth, the resulting loss of sensory input disrupts vestibulo-ocular reflexes (VORs) and vestibulo-spinal reflexes that normally stabilize the eyes and body. Affected individuals suffer poor vision during head movement, postural instability, chronic disequilibrium, and cognitive distraction. Although most individuals with residual sensation compensate for their loss over time, others fail to do so and have no adequate treatment options. A vestibular prosthesis analogous to cochlear implants but designed to modulate vestibular nerve activity during head movement should improve quality of life for these chronically dizzy individuals. We describe the impact of bilateral loss of vestibular sensation, animal studies supporting feasibility of prosthetic vestibular stimulation, the current status of multichannel vestibular sensory replacement prosthesis development, and challenges to successfully realizing this approach in clinical practice. In bilaterally vestibular-deficient rodents and rhesus monkeys, the Johns Hopkins multichannel vestibular prosthesis (MVP) partially restores the three-dimensional (3D) VOR for head rotations about any axis. Attempts at prosthetic vestibular stimulation of humans have not yet included the 3D eye movement assays necessary to accurately evaluate VOR alignment, but these initial forays have revealed responses that are otherwise comparable to observations in animals. Current efforts now focus on refining electrode design and surgical technique to enhance stimulus selectivity and preserve cochlear function, optimizing stimulus protocols to improve dynamic range and reduce excitation-inhibition asymmetry, and adapting laboratory MVP prototypes into devices

  13. Contribution of the cerebellar flocculus to gaze control during active head movements

    NASA Technical Reports Server (NTRS)

    Belton, T.; McCrea, R. A.; Peterson, B. W. (Principal Investigator)

    1999-01-01

    The flocculus and ventral paraflocculus are adjacent regions of the cerebellar cortex that are essential for controlling smooth pursuit eye movements and for altering the performance of the vestibulo-ocular reflex (VOR). The question addressed in this study is whether these regions of the cerebellum are more globally involved in controlling gaze, regardless of whether eye or active head movements are used to pursue moving visual targets. Single-unit recordings were obtained from Purkinje (Pk) cells in the floccular region of squirrel monkeys that were trained to fixate and pursue small visual targets. Cell firing rate was recorded during smooth pursuit eye movements, cancellation of the VOR, combined eye-head pursuit, and spontaneous gaze shifts in the absence of targets. Pk cells were found to be much less sensitive to gaze velocity during combined eye-head pursuit than during ocular pursuit. They were not sensitive to gaze or head velocity during gaze saccades. Temporary inactivation of the floccular region by muscimol injection compromised ocular pursuit but had little effect on the ability of monkeys to pursue visual targets with head movements or to cancel the VOR during active head movements. Thus the signals produced by Pk cells in the floccular region are necessary for controlling smooth pursuit eye movements but not for coordinating gaze during active head movements. The results imply that individual functional modules in the cerebellar cortex are less involved in the global organization and coordination of movements than with parametric control of movements produced by a specific part of the body.

  14. In Vitro Susceptibility and Trailing Growth Effect of Clinical Isolates of Candida Species to Azole Drugs

    PubMed Central

    Zomorodian, Kamiar; Bandegani, Azadeh; Mirhendi, Hossein; Pakshir, Keyvan; Alinejhad, Navvab; Poostforoush Fard, Ali

    2016-01-01

    Background: Emergence of resistance to respective antifungal drugs is a primary concern for the treatment of candidiasis. Hence, determining antifungal susceptibility of the isolated yeasts is of special importance for effective therapy. For this purpose, the clinical laboratory standard institute (CLSI) has introduced a broth microdilution method to determine minimum inhibitory concentration (MIC). However, the so-called “Trailing effect” phenomenon might sometimes pose ambiguity in the interpretation of the results. Objectives: The present study aimed to determine the in vitro susceptibility of clinical isolates of Candida against azoles and the frequency of the Trailing effect. Materials and Methods: A total of 193 Candida isolates were prospectively collected and identified through the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Using a broth microdilution test, according to the guidelines of CLSI M27-A3, antifungal susceptibilities of the isolated yeasts against Fluconazole (FLU), Itraconazole (ITR), Ketoconazole (KET) and Voriconazole (VOR) were assessed. Moreover, trailing growth was determined when a susceptible MIC was incubated for 24 hours, and turned into a resistant one after 48 hours of incubation. Results: Among the tested antifungal drugs in this study, the highest rate of resistance was observed against ITR (28.5%) followed by VOR (26.4%), FLU (20.8%) and KET (1.5%). The trailing effect was induced in 27 isolates (14.0%) by VOR, in 26 isolates (13.5%) by ITR, in 24 isolates (12.4%) by FLU, and in 19 isolates (9.8%) by KET. Conclusions: The monitoring of antifungal susceptibilities of Candida species isolated from clinical sources is highly recommended for the efficient management of patients. Moreover, the trailing effect should be taken into consideration once the interpretation of the results is intended. PMID:27127587

  15. Age-Related Neurochemical Changes in the Vestibular Nuclei

    PubMed Central

    Smith, Paul F.

    2016-01-01

    There is evidence that the normal aging process is associated with impaired vestibulo-ocular reflexes (VOR) and vestibulo-spinal reflexes, causing reduced visual acuity and postural instability. Nonetheless, the available evidence is not entirely consistent, especially with respect to the VOR. Some recent studies have reported that VOR gain can be intact even above 80 years of age. Similarly, although there is evidence for age-related hair cell loss and neuronal loss in Scarpa’s ganglion and the vestibular nucleus complex (VNC), it is not entirely consistent. Whatever structural and functional changes occur in the VNC as a result of aging, either to cause vestibular impairment or to compensate for it, neurochemical changes must underlie them. However, the neurochemical changes that occur in the VNC with aging are poorly understood because the available literature is very limited. This review summarizes and critically evaluates the available evidence relating to the noradrenaline, serotonin, dopamine, glutamate, GABA, glycine, and nitric oxide neurotransmitter systems in the aging VNC. It is concluded that, at present, it is difficult, if not impossible, to relate the neurochemical changes observed to the function of specific VNC neurons and whether the observed changes are the cause of a functional deficit in the VNC or an effect of it. A better understanding of the neurochemical changes that occur during aging may be important for the development of potential drug treatments for age-related vestibular disorders. However, this will require the use of more sophisticated methodology such as in vivo microdialysis with single neuron recording and perhaps new technologies such as optogenetics. PMID:26973593

  16. Age-Related Neurochemical Changes in the Vestibular Nuclei.

    PubMed

    Smith, Paul F

    2016-01-01

    There is evidence that the normal aging process is associated with impaired vestibulo-ocular reflexes (VOR) and vestibulo-spinal reflexes, causing reduced visual acuity and postural instability. Nonetheless, the available evidence is not entirely consistent, especially with respect to the VOR. Some recent studies have reported that VOR gain can be intact even above 80 years of age. Similarly, although there is evidence for age-related hair cell loss and neuronal loss in Scarpa's ganglion and the vestibular nucleus complex (VNC), it is not entirely consistent. Whatever structural and functional changes occur in the VNC as a result of aging, either to cause vestibular impairment or to compensate for it, neurochemical changes must underlie them. However, the neurochemical changes that occur in the VNC with aging are poorly understood because the available literature is very limited. This review summarizes and critically evaluates the available evidence relating to the noradrenaline, serotonin, dopamine, glutamate, GABA, glycine, and nitric oxide neurotransmitter systems in the aging VNC. It is concluded that, at present, it is difficult, if not impossible, to relate the neurochemical changes observed to the function of specific VNC neurons and whether the observed changes are the cause of a functional deficit in the VNC or an effect of it. A better understanding of the neurochemical changes that occur during aging may be important for the development of potential drug treatments for age-related vestibular disorders. However, this will require the use of more sophisticated methodology such as in vivo microdialysis with single neuron recording and perhaps new technologies such as optogenetics. PMID:26973593

  17. Prevalence of Vestibular Disorder in Older People Who Experience Dizziness.

    PubMed

    Chau, Allan T; Menant, Jasmine C; Hübner, Patrick P; Lord, Stephen R; Migliaccio, Americo A

    2015-01-01

    Dizziness and imbalance are clinically poorly defined terms, which affect ~30% of people over 65 years of age. In these people, it is often difficult to define the primary cause of dizziness, as it can stem from cardiovascular, vestibular, psychological, and neuromuscular causes. However, identification of the primary cause is vital in determining the most effective treatment strategy for a patient. Our aim is to accurately identify the prevalence of benign paroxysmal positional vertigo (BPPV), peripheral, and central vestibular hypofunction in people aged over 50 years who had experienced dizziness within the past year. Seventy-six participants aged 51-92 (mean ± SD = 69 ± 9.5 years) were tested using the head thrust dynamic visual acuity (htDVA) test, dizziness handicap inventory (DHI), as well as sinusoidal and unidirectional rotational chair testing, in order to obtain data for htDVA score, DHI score, sinusoidal (whole-body, 0.1-2 Hz with peak velocity at 30°/s) vestibulo-ocular reflex (VOR) gain and phase, transient (whole-body, acceleration at 150°/s(2) to a constant velocity rotation of 50°/s) VOR gain and time constant (TC), optokinetic nystagmus (OKN) gain, and TC (whole-body, constant velocity rotation at 50°/s). We found that BPPV, peripheral and central vestibular hypofunction were present in 38 and 1% of participants, respectively, suggesting a likely vestibular cause of dizziness in these people. Of those with a likely vestibular cause, 63% had BPPV; a figure higher than previously reported in dizziness clinics of ~25%. Our results indicate that htDVA, sinusoidal (particularly 0.5-1 Hz), and transient VOR testing were the most effective at detecting people with BPPV or vestibular hypofunction, whereas DHI and OKN were effective at only detecting non-BPPV vestibular hypofunction. PMID:26733940

  18. Dynamic Visual Acuity: a Functionally Relevant Research Tool

    NASA Technical Reports Server (NTRS)

    Peters, Brian T.; Brady, Rachel A.; Miller, Chris A.; Mulavara, Ajitkumar P.; Wood, Scott J.; Cohen, Helen S.; Bloomberg, Jacob J.

    2010-01-01

    Coordinated movements between the eyes and head are required to maintain a stable retinal image during head and body motion. The vestibulo-ocular reflex (VOR) plays a significant role in this gaze control system that functions well for most daily activities. However, certain environmental conditions or interruptions in normal VOR function can lead to inadequate ocular compensation, resulting in oscillopsia, or blurred vision. It is therefore possible to use acuity to determine when the environmental conditions, VOR function, or the combination of the two is not conductive for maintaining clear vision. Over several years we have designed and tested several tests of dynamic visual acuity (DVA). Early tests used the difference between standing and walking acuity to assess decrements in the gaze stabilization system after spaceflight. Supporting ground-based studies measured the responses from patients with bilateral vestibular dysfunction and explored the effects of visual target viewing distance and gait cycle events on walking acuity. Results from these studies show that DVA is affected by spaceflight, is degraded in patients with vestibular dysfunction, changes with target distance, and is not consistent across the gait cycle. We have recently expanded our research to include studies in which seated subjects are translated or rotated passively. Preliminary results from this work indicate that gaze stabilization ability may differ between similar active and passive conditions, may change with age, and can be affected by the location of the visual target with respect to the axis of motion. Use of DVA as a diagnostic tool is becoming more popular but the functional nature of the acuity outcome measure also makes it ideal for identifying conditions that could lead to degraded vision. By doing so, steps can be taken to alter the problematic environments to improve the man-machine interface and optimize performance.

  19. Effect of Target Location on Dynamic Visual Acuity During Passive Horizontal Rotation

    NASA Technical Reports Server (NTRS)

    Appelbaum, Meghan; DeDios, Yiri; Kulecz, Walter; Peters, Brian; Wood, Scott

    2010-01-01

    The vestibulo-ocular reflex (VOR) generates eye rotation to compensate for potential retinal slip in the specific plane of head movement. Dynamic visual acuity (DVA) has been utilized as a functional measure of the VOR. The purpose of this study was to examine changes in accuracy and reaction time when performing a DVA task with targets offset from the plane of rotation, e.g. offset vertically during horizontal rotation. Visual acuity was measured in 12 healthy subjects as they moved a hand-held joystick to indicate the orientation of a computer-generated Landolt C "as quickly and accurately as possible." Acuity thresholds were established with optotypes presented centrally on a wall-mounted LCD screen at 1.3 m distance, first without motion (static condition) and then while oscillating at 0.8 Hz (DVA, peak velocity 60 deg/s). The effect of target location was then measured during horizontal rotation with the optotypes randomly presented in one of nine different locations on the screen (offset up to 10 deg). The optotype size (logMar 0, 0.2 or 0.4, corresponding to Snellen range 20/20 to 20/50) and presentation duration (150, 300 and 450 ms) were counter-balanced across five trials, each utilizing horizontal rotation at 0.8 Hz. Dynamic acuity was reduced relative to static acuity in 7 of 12 subjects by one step size. During the random target trials, both accuracy and reaction time improved proportional to optotype size. Accuracy and reaction time also improved between 150 ms and 300 ms presentation durations. The main finding was that both accuracy and reaction time varied as a function of target location, with greater performance decrements when acquiring vertical targets. We conclude that dynamic visual acuity varies with target location, with acuity optimized for targets in the plane of motion. Both reaction time and accuracy are functionally relevant DVA parameters of VOR function.

  20. Yaw and pitch visual-vestibular interaction in weightlessness

    NASA Technical Reports Server (NTRS)

    Clement, G.; Wood, S. J.; Reschke, M. F.; Berthoz, A.; Igarashi, M.

    1999-01-01

    Both yaw and pitch visual-vestibular interactions at two separate frequencies of chair rotation (0.2 and 0.8 Hz) in combination with a single velocity of optokinetic stimulus (36 degrees/s) were used to investigate the effects of sustained weightlessness on neural strategies adopted by astronaut subjects to cope with the stimulus rearrangement of spaceflight. Pitch and yaw oscillation in darkness at 0.2 and 0.8 Hz without optokinetic stimulation, and constant velocity linear optokinetic stimulation at 18, 36, and 54 degrees/s presented relative to the head with the subject stationary, were used as controls for the visual-vestibular interactions. The results following 8 days of space flight showed no significant changes in: (1) either the horizontal and vertical vestibulo-ocular reflex (VOR) gain, phase, or bias; (2) the yaw visual-vestibular response (VVR); or (3) the horizontal or vertical optokinetic (OKN) slow phase velocity (SPV). However, significant changes were observed: (1) when during pitch VVR at 0.2 Hz late inflight, the contribution of the optokinetic input to the combined oculomotor response was smaller than during the stationary OKN SPV measurements, followed by an increased contribution during the immediate postflight testing; and (2) when during pitch VVR at 0.8 Hz, the component of the combined oculomotor response due to the underlying vertical VOR was more efficiently suppressed early inflight and less suppressed immediately postflight compared with preflight observations. The larger OKN response during pitch VVR at 0.2 Hz and the better suppression of VOR during pitch VVR at 0.8 Hz postflight are presumably due to the increased role of vision early inflight and immediately after spaceflight, as previously observed in various studies. These results suggest that the subjects adopted a neural strategy to structure their spatial orientation in weightlessness by reweighting visual, otolith, and perhaps tactile/somatic signals.

  1. Binocular Coordination of the Human Vestibulo-Ocular Reflex during Off-axis Pitch Rotation

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Reschke, M. F.; Kaufman, G. D.; Black, F. O.; Paloski, W. H.

    2006-01-01

    Head movements in the sagittal pitch plane typically involve off-axis rotation requiring both vertical and horizontal vergence ocular reflexes to compensate for angular and translational motion relative to visual targets of interest. The purpose of this study was to compare passive pitch VOR responses during rotation about an Earth-vertical axis (canal only cues) with off-axis rotation (canal and otolith cues). Methods. Eleven human subjects were oscillated sinusoidally at 0.13, 0.3 and 0.56 Hz while lying left-side down with the interaural axis either aligned with the axis of rotation or offset by 50 cm. In a second set of measurements, twelve subjects were also tested during sinusoidally varying centrifugation over the same frequency range. The modulation of vertical and horizontal vergence ocular responses was measured with a binocular videography system. Results. Off-axis pitch rotation enhanced the vertical VOR at lower frequencies and enhanced the vergence VOR at higher frequencies. During sinusoidally varying centrifugation, the opposite trend was observed for vergence, with both vertical and vergence vestibulo-ocular reflexes being suppressed at the highest frequency. Discussion. These differential effects of off-axis rotation over the 0.13 to 0.56 Hz range are consistent with the hypothesis that otolith-ocular reflexes are segregated in part on the basis of stimulus frequency. At the lower frequencies, tilt otolith-ocular responses compensate for declining canal input. At higher frequencies, translational otolith-ocular reflexes compensate for declining visual contributions to the kinematic demands required for fixating near targets.

  2. Vestibulo-spinal and vestibulo-ocular reflexes are modulated when standing with increased postural threat.

    PubMed

    Naranjo, E N; Cleworth, T W; Allum, J H J; Inglis, J T; Lea, J; Westerberg, B D; Carpenter, M G

    2016-02-01

    We investigated how vestibulo-spinal reflexes (VSRs) and vestibulo-ocular reflexes (VORs) measured through vestibular evoked myogenic potentials (VEMPs) and video head impulse test (vHIT) outcomes, respectively, are modulated during standing under conditions of increased postural threat. Twenty-five healthy young adults stood quietly at low (0.8 m from the ground) and high (3.2 m) surface height conditions in two experiments. For the first experiment (n = 25) VEMPs were recorded with surface EMG from inferior oblique (IO), sternocleidomastoid (SCM), trapezius (TRP), and soleus (SOL) muscles in response to 256 air-conducted short tone bursts (125 dB SPL, 500 Hz, 4 ms) delivered via headphones. A subset of subjects (n = 19) also received horizontal and vertical head thrusts (∼150°/s) at each height in a separate session, comparing eye and head velocities by using a vHIT system for calculating the functional VOR gains. VEMP amplitudes (IO, TRP, SOL) and horizontal and vertical vHIT gains all increased with high surface height conditions (P < 0.05). Changes in IO and SCM VEMP amplitudes as well as horizontal vHIT gains were correlated with changes in electrodermal activity (ρ = 0.44-0.59, P < 0.05). VEMP amplitude for the IO also positively correlated with fear (ρ = 0.43, P = 0.03). Threat-induced anxiety, fear, and arousal have significant effects on VSR and VOR gains that can be observed in both physiological and functional outcome measures. These findings provide support for a potential central modulation of the vestibular nucleus complex through excitatory inputs from neural centers involved in processing fear, anxiety, arousal, and vigilance. PMID:26631147

  3. Bilaterally Abnormal Head Impulse Tests Indicate a Large Cerebellopontine Angle Tumor

    PubMed Central

    Kim, Hyo-Jung; Park, Seong-Ho; Koo, Ja Won; Kim, Chae-Yong; Kim, Young-Hoon; Han, Jung Ho

    2016-01-01

    Background and Purpose Tumors involving the cerebellopontine angle (CPA) pose a diagnostic challenge due to their diverse manifestations. Head impulse tests (HITs) have been used to evaluate vestibular function, but few studies have explored the head impulse gain of the vestibulo-ocular reflex (VOR) in patients with a vestibular schwannoma. This study tested whether the head impulse gain of the VOR is an indicator of the size of a unilateral CPA tumor. Methods Twenty-eight patients (21 women; age=64±12 years, mean±SD) with a unilateral CPA tumor underwent a recording of the HITs using a magnetic search coil technique. Patients were classified into non-compressing (T1-T3) and compressing (T4) groups according to the Hannover classification. Results Most (23/28, 82%) of the patients showed abnormal HITs for the semicircular canals on the lesion side. The bilateral abnormality in HITs was more common in the compressing group than the non-compressing group (80% vs. 8%, Pearson's chi-square test: p<0.001). The tumor size was inversely correlated with the head impulse gain of the VOR in either direction. Conclusions Bilaterally abnormal HITs indicate that a patient has a large unilateral CPA tumor. The abnormal HITs in the contralesional direction may be explained either by adaptation or by compression and resultant dysfunction of the cerebellar and brainstem structures. The serial evaluation of HITs may provide information on tumor growth, and thereby reduce the number of costly brain scans required when following up patients with CPA tumors. PMID:26754780

  4. Progress Toward Development of a Multichannel Vestibular Prosthesis for Treatment of Bilateral Vestibular Deficiency

    PubMed Central

    FRIDMAN, GENE Y.; DELLA SANTINA, CHARLES C.

    2014-01-01

    This article reviews vestibular pathology and the requirements and progress made in the design and construction of a vestibular prosthesis. Bilateral loss of vestibular sensation is disabling. When vestibular hair cells are injured by ototoxic medications or other insults to the labyrinth, the resulting loss of sensory input disrupts vestibulo-ocular reflexes (VORs) and vestibulo-spinal reflexes that normally stabilize the eyes and body. Affected individuals suffer poor vision during head movement, postural instability, chronic disequilibrium, and cognitive distraction. Although most individuals with residual sensation compensate for their loss over time, others fail to do so and have no adequate treatment options. A vestibular prosthesis analogous to cochlear implants but designed to modulate vestibular nerve activity during head movement should improve quality of life for these chronically dizzy individuals. We describe the impact of bilateral loss of vestibular sensation, animal studies supporting feasibility of prosthetic vestibular stimulation, the current status of multichannel vestibular sensory replacement prosthesis development, and challenges to successfully realizing this approach in clinical practice. In bilaterally vestibular-deficient rodents and rhesus monkeys, the Johns Hopkins multichannel vestibular prosthesis (MVP) partially restores the three-dimensional (3D) VOR for head rotations about any axis. Attempts at prosthetic vestibular stimulation of humans have not yet included the 3D eye movement assays necessary to accurately evaluate VOR alignment, but these initial forays have revealed responses that are otherwise comparable to observations in animals. Current efforts now focus on refining electrode design and surgical technique to enhance stimulus selectivity and preserve cochlear function, optimizing stimulus protocols to improve dynamic range and reduce excitation–inhibition asymmetry, and adapting laboratory MVP prototypes into devices

  5. Implications of rotational kinematics for the oculomotor system in three dimensions.

    PubMed

    Tweed, D; Vilis, T

    1987-10-01

    1. This paper develops three-dimensional models for the vestibuloocular reflex (VOR) and the internal feedback loop of the saccadic system. The models differ qualitatively from previous, one-dimensional versions, because the commutative algebra used in previous models does not apply to the three-dimensional rotations of the eye. 2. The hypothesis that eye position signals are generated by an eye velocity integrator in the indirect path of the VOR must be rejected because in three dimensions the integral of angular velocity does not specify angular position. Computer simulations using eye velocity integrators show large, cumulative gaze errors and post-VOR drift. We describe a simple velocity to position transformation that works in three dimensions. 3. In the feedback control of saccades, eye position error is not the vector difference between actual and desired eye positions. Subtractive feedback models must continuously adjust the axis of rotation throughout a saccade, and they generate meandering, dysmetric gaze saccades. We describe a multiplicative feedback system that solves these problems and generates fixed-axis saccades that accord with Listing's law. 4. We show that Listing's law requires that most saccades have their axes out of Listing's plane. A corollary is that if three pools of short-lead burst neurons code the eye velocity command during saccades, the three pools are not yoked, but function independently during visually triggered saccades. 5. In our three-dimensional models, we represent eye position using four-component rotational operators called quaternions. This is not the only algebraic system for describing rotations, but it is the one that best fits the needs of the oculomotor system, and it yields much simpler models than do rotation matrix or other representations. 6. Quaternion models predict that eye position is represented on four channels in the oculomotor system: three for the vector components of eye position and one inversely

  6. Flight evaluation of LORAN-C in the State of Vermont

    NASA Technical Reports Server (NTRS)

    Mackenzie, F. D.; Lytle, C. D.

    1981-01-01

    A flight evaluation of LORAN C as a supplement to existing navigation aids for general aviation aircraft, particularly in mountainous regions of the United States and where VOR coverage is limited was conducted. Flights, initiated in the summer months, extend through four seasons and practically all weather conditions typical of northeastern U.S. operations. Assessment of all the data available indicates that LORAN C signals are suitable as a means of navigation during enroute, terminal and nonprecision approach operations and the performance exceeds the minimum accuracy criteria.

  7. Stabilization of gaze during circular locomotion in darkness. II. Contribution of velocity storage to compensatory eye and head nystagmus in the running monkey

    NASA Technical Reports Server (NTRS)

    Solomon, D.; Cohen, B.

    1992-01-01

    1. Yaw eye in head (Eh) and head on body velocities (Hb) were measured in two monkeys that ran around the perimeter of a circular platform in darkness. The platform was stationary or could be counterrotated to reduce body velocity in space (Bs) while increasing gait velocity on the platform (Bp). The animals were also rotated while seated in a primate chair at eccentric locations to provide linear and angular accelerations similar to those experienced while running. 2. Both animals had head and eye nystagmus while running in darkness during which slow phase gaze velocity on the body (Gb) partially compensated for body velocity in space (Bs). The eyes, driven by the vestibuloocular reflex (VOR), supplied high-frequency characteristics, bringing Gb up to compensatory levels at the beginning and end of the slow phases. The head provided substantial gaze compensation during the slow phases, probably through the vestibulocollic reflex (VCR). Synchronous eye and head quick phases moved gaze in the direction of running. Head movements occurred consistently only when animals were running. This indicates that active body and limb motion may be essential for inducing the head-eye gaze synergy. 3. Gaze compensation was good when running in both directions in one animal and in one direction in the other animal. The animals had long VOR time constants in these directions. The VOR time constant was short to one side in one animal, and it had poor gaze compensation in this direction. Postlocomotory nystagmus was weaker after running in directions with a long VOR time constant than when the animals were passively rotated in darkness. We infer that velocity storage in the vestibular system had been activated to produce continuous Eh and Hb during running and to counteract postrotatory afterresponses. 4. Continuous compensatory gaze nystagmus was not produced by passive eccentric rotation with the head stabilized or free. This indicates that an aspect of active locomotion, most

  8. Sicheres Navigieren in dynamischen Umgebungen mit 3D-Kollisionsvermeidung

    NASA Astrophysics Data System (ADS)

    Stiene, Stefan; Hertzberg, Joachim

    Diese Papier stellt eine neuartige Methode vor, die 3D-Hindernisvermeidung ermöglicht. Die Sensorkonfiguration beruht auf sechs Laserscannern, die die gesamte Roboteroberfläche abdecken. Die Daten der sechs Laserscanner werden zu einem virtuellen, zweidimensionalen, horizontal ausgerichteten 360°-Laserscanner kombiniert. Da der virtuelle Laserscanner die 3D-Umgebung in einem zweidimensionalen Datensatz repräsentiert, ermöglicht er in Kombination mit klassischen Hindernisvermeidungsalgorithmen wie der Vector Field Histogram Methode eine 3D-Hindernisvermeidung.

  9. Automatic Navaids Checkout System. [for space shuttle electronics

    NASA Technical Reports Server (NTRS)

    Belver, T. L.; Junk, W. S.

    1974-01-01

    An automatic Navaids Checkout System for use in Space Shuttle development is discussed. The groundwork leading to the development is presented, followed by a description of the hardware. Finally, system utilization including operator interface and system software is discussed. The Navaids Checkout System is extremely flexible with capability to handle different test articles with a minimum of hardware reconfiguration. Application software is written in a high level user-oriented test language. The checkout system has been in operation for approximately one year with capability to handle VOR, ILS, TACAN, ATC Radar Beacon, and UHF/VHF communications equipment.

  10. Comparison of different exercise programs in the rehabilitation of patients with chronic peripheral vestibular dysfunction.

    PubMed

    Szturm, T; Ireland, D J; Lessing-Turner, M

    1994-01-01

    The purpose of this study was to evaluate the effects of two exercise programs on balance performance in patients with chronic peripheral vestibular dysfunction and to assess whether these exercise programs induce adaptive modifications of the vestibulo-ocular reflex (VOR). Patients were randomly assigned to one of two groups. (1) Those in the Rehab (Reh) group (n = 11) received a comprehensive exercise program that consisted of balance retraining and goal-directed eye-head exercises under combinations of varied visual and somatosensory sensory conditions. Patients received 45-minute training sessions, three times per week for 12 weeks, and were instructed on a custom home exercise program. (2) Those in the Home group (n = 12) were instructed to perform the Cooksey-Cawthorne eye-head exercises at home, on a daily basis, for 12 weeks. In addition, after completion of the exercise program and a follow-up period, 7 of the participants in the Home group (here defined as the A group) chose to enter the Reh program (here defined as the B group). Balance performance was assessed by measuring the peak-to-peak magnitude and total amount of anterior-posterior body sway, and of horizontal (shear) ground reaction force during six test conditions, in which visual and somatosensory orientation cues were reduced or altered by rotation of the visual surround or support surface in proportion to the subject's sway, and in which vision was eliminated (eyes closed). The VOR response to step chair rotations of 60 degrees/s and 120 degrees/s, and the optokinetic reflex (OKN) response to 60 degrees/s constant velocity optokinetic stimuli were recorded. Left-right difference in VOR gain, VOR time constant, and OKN gain were determined. These tests were performed 1 day prior to start of treatment (TD 1), 6 weeks after start of treatment (TD 2), at the end of the 12-week treatment period (TD 3), and 5 months after end of treatment (TD 4). The findings revealed a significant improvement in

  11. Toward achieving global sole means radionavigation systems

    NASA Technical Reports Server (NTRS)

    Vangraas, F.

    1992-01-01

    This paper briefly reviews tentative requirements for global, earth-referenced sole means of navigation systems with emphasis on integrity and availability. These requirements can be allocated to integrated navigation system architectures based on for instance GPS, GLONASS, VOR/DME, TACAN, Omega, Chayka, and Loran-C. Fault detection and isolation techniques (FDI) for integrated radio navigation systems are presented. The FDI algorithm provides a protection radius with a specified confidence level as a function of measurement geometry and algorithm requirements. This is followed by a case study of integrated GPS/Loran-C.

  12. Histone Deacetylase Inhibitor Romidepsin Induces HIV Expression in CD4 T Cells from Patients on Suppressive Antiretroviral Therapy at Concentrations Achieved by Clinical Dosing

    PubMed Central

    Wei, Datsen George; Chiang, Vicki; Fyne, Elizabeth; Balakrishnan, Mini; Barnes, Tiffany; Graupe, Michael; Hesselgesser, Joseph; Irrinki, Alivelu; Murry, Jeffrey P.; Stepan, George; Stray, Kirsten M.; Tsai, Angela; Yu, Helen; Spindler, Jonathan; Kearney, Mary; Spina, Celsa A.; McMahon, Deborah; Lalezari, Jacob; Sloan, Derek; Mellors, John; Geleziunas, Romas; Cihlar, Tomas

    2014-01-01

    Persistent latent reservoir of replication-competent proviruses in memory CD4 T cells is a major obstacle to curing HIV infection. Pharmacological activation of HIV expression in latently infected cells is being explored as one of the strategies to deplete the latent HIV reservoir. In this study, we characterized the ability of romidepsin (RMD), a histone deacetylase inhibitor approved for the treatment of T-cell lymphomas, to activate the expression of latent HIV. In an in vitro T-cell model of HIV latency, RMD was the most potent inducer of HIV (EC50 = 4.5 nM) compared with vorinostat (VOR; EC50 = 3,950 nM) and other histone deacetylase (HDAC) inhibitors in clinical development including panobinostat (PNB; EC50 = 10 nM). The HIV induction potencies of RMD, VOR, and PNB paralleled their inhibitory activities against multiple human HDAC isoenzymes. In both resting and memory CD4 T cells isolated from HIV-infected patients on suppressive combination antiretroviral therapy (cART), a 4-hour exposure to 40 nM RMD induced a mean 6-fold increase in intracellular HIV RNA levels, whereas a 24-hour treatment with 1 µM VOR resulted in 2- to 3-fold increases. RMD-induced intracellular HIV RNA expression persisted for 48 hours and correlated with sustained inhibition of cell-associated HDAC activity. By comparison, the induction of HIV RNA by VOR and PNB was transient and diminished after 24 hours. RMD also increased levels of extracellular HIV RNA and virions from both memory and resting CD4 T-cell cultures. The activation of HIV expression was observed at RMD concentrations below the drug plasma levels achieved by doses used in patients treated for T-cell lymphomas. In conclusion, RMD induces HIV expression ex vivo at concentrations that can be achieved clinically, indicating that the drug may reactivate latent HIV in patients on suppressive cART. PMID:24722454

  13. Head impulse gain and saccade analysis in pontine-cerebellar stroke and vestibular neuritis

    PubMed Central

    Todd, Michael; Halmagyi, Gabor M.; Aw, Swee

    2014-01-01

    Objective: We sought to quantify and compare angular vestibulo-ocular reflex (aVOR) gain and compensatory saccade properties elicited by the head impulse test (HIT) in pontine-cerebellar stroke (PCS) and vestibular neuritis (VN). Methods: Horizontal HIT was recorded ≤7 days from vertigo onset with dual-search coils in 33 PCS involving the anterior inferior, posterior inferior, and superior cerebellar arteries (13 AICA, 17 PICA, 3 SCA) confirmed by MRI and 20 VN. We determined the aVOR gain and asymmetry, and compensatory overt saccade properties including amplitude asymmetry and cumulative amplitude (ipsilesional trials [I]; contralesional trials [C]). Results: The aVOR gain (normal: 0.96; asymmetry = 2%) was bilaterally reduced, greater in AICA (I = 0.39, C = 0.57; asymmetry = 20%) than in PICA/SCA strokes (I = 0.75, C = 0.74; asymmetry = 7%), in contrast to the unilateral deficit in VN (I = 0.22, C = 0.76; asymmetry = 54%). Cumulative amplitude (normal: 1.1°) was smaller in AICA (I = 4.2°, C = 3.0°) and PICA/SCA strokes (I = 2.1°, C = 3.0°) compared with VN (I = 8.5°, C = 1.3°). Amplitude asymmetry in AICA and PICA/SCA strokes was comparable, but favored the contralesional side in PICA/SCA strokes and the ipsilesional side in VN. Saccade asymmetry <61% was found in 97% of PCS and none of VN. Gain asymmetry <40% was found in 94% of PCS and 10% of VN. Conclusion: HIT gains and compensatory saccades differ between PCS and VN. VN was characterized by unilateral gain deficits with asymmetric large saccades, AICA stroke by more symmetric bilateral gain reduction with smaller saccades, and PICA stroke by contralesional gain bias with the smallest saccades. Saccade and gain asymmetry should be investigated further in future diagnostic accuracy studies. Classification of evidence: This study provides Class II evidence that aVOR testing accurately distinguishes patients with PCS from VN (sensitivity 94%–97%, specificity 90%–100%). PMID:25253747

  14. System for providing an integrated display of instantaneous information relative to aircraft attitude, heading, altitude, and horizontal situation

    NASA Technical Reports Server (NTRS)

    James, R. (Inventor)

    1981-01-01

    A display device is disclosed which is particularly suited for providing the pilot of an aircraft with combined inflight attitude, heading, altitude, and horizontal situation information previously available only by using two or three devices providing separate displays. The preferred embodiment combines a commonly used and commercially available flight director-type device for providing a display in combination with a miniature aircraft supported for angular displacement from a vertical orientation to indicate heading error, or heading offset, and an extended course deviation indicator bar which projects into juxtaposition with the miniature aircraft for providing a true picture of the aircraft's horizontal situation relative to a selective VOR, ILS, or MLS course.

  15. Von Donuts und Zucker: Mit Neutronen biologische Makromoleküle erforschen

    NASA Astrophysics Data System (ADS)

    May, Roland P.

    2003-05-01

    Für die Erforschung von Biomolekülen bieten Neutronen einzigartige Eigenschaften. Vor allem ihre unterschiedliche Wechselwirkung mit dem natürlichen Wasserstoff und seinem schweren Isotop Deuterium ermöglicht tiefe Einblicke in Struktur, Funktion und Dynamik von Proteinen, Nukleinsäuren und Biomembranen. Bei vielen Fragestellungen zur Strukturaufklärung gibt es kaum oder keine Alternative zum Neutron. Das Institut Laue-Langevin trägt Bahnbrechendes zum Erfolg der Neutronen-Methoden in der Biologie bei.

  16. Computational Aeroacoustic Analysis of Slat Trailing-Edge Flow

    NASA Technical Reports Server (NTRS)

    Singer, Bart A.; Lockhard, David P.; Brentner, Kenneth S.; Khorrami, Mehdi R.; Berkman, Mert E.; Choudhari, Meelan

    2000-01-01

    An acoustic analysis based on the Ffowcs Williams and Hawkings equation was performed for a high-lift system. As input, the acoustic analysis used un- steady flow data obtained from a highly resolved, time-dependent, Reynolds-averaged Navier-Stokes calculation. The analysis strongly suggests that vor- tex shedding from the trailing edge of the slat results in a high-amplitude, high-frequency acoustic signal, similar to that which was observed in a correspond- ing experimental study of the high-lift system.

  17. Das menschliche Gehör und Grundlagen der Psychoakustik

    NASA Astrophysics Data System (ADS)

    Genuit, Klaus; Sottek, Roland

    Das menschliche Gehör ist ein äußerst komplexes Empfangs- und Signalverarbeitungssystem. Es ist als Schallanalysator in Leistungsfähigkeit und Vielseitigkeit von technisch-analytischen Verfahren nach wie vor unerreicht. Die Signalverarbeitung läuft auf Grundlage komplexer Prozesse ab, die in ihrer Gesamtheit bislang nicht vollständig erfasst sind. Verschiedene Modelle zur gehörgerechten Zeit- und Frequenzanalyse ahmen jene komplexen Prozesse und Verarbeitungsmechanismen nach, die im menschlichen Gehör vollzogen werden.

  18. MYXINOIDA, Schleimaale, Inger

    NASA Astrophysics Data System (ADS)

    Rieger, Gunde; Maier, Wolfgang

    Schleimaale leben in Bodennähe bzw. im Schlamm eingegraben in allen Ozeanen bis in 2500 m Tiefe, bevorzugt in mehr als 30 m Tiefe in küstennahen Bereichen der gemäßigten Breiten. Geringere Salinität und vor allem Wassertemperaturen über 20°C sind limitierende Faktoren für ihr Vorkommen, das sich daher in wärmeren Zonen auf größere Tiefen beschränkt. Auch vom East Pacific Rise ist seit kurzem eine neue Art der Gattung Eptatretus bekannt (S. 198).

  19. Revival of the dark core in scattered optical vortices

    NASA Astrophysics Data System (ADS)

    Reddy, Salla G.; Kumar, Ashok; Prabhakar, Shashi; Singh, R. P.

    2013-09-01

    We have experimentally observed the revival of the dark core in the far field intensity distribution in optical vor­ tices after scattering through rotating ground glass plate. The diameter and darkness of the core is independent of the speed of the rotating ground glass plate. They depend on the spot size and azimuthal index of the beam incident on it. This shows that the spatial coherence of the scattered light is independent of the speed of the rotating ground glass plate. Our experimental results are in good agreement with the numerical results based on the theory given by Wang, Cai and Korotkova (Opt. Exp. 17, 22366 (2009)).

  20. Kopf

    NASA Astrophysics Data System (ADS)

    Goldschmid, Alfred; Maier, Wolfgang; Olsson, Lennart; Piekarski, Nadine

    Die Evolution des Wirbeltierkopfes ist ein klassisches Problemfeld der vergleichend en Morphologie. Bereits J.W. von Goethe (1749-1832) und L. Oken (1779-1851) vertraten die Idee eines aus Segmenten bestehenden Schädels. Die Segmente sollten umgewandelten Wirbeln entsprechen; später wurden auch die Hirnnerven den segmentalen Spinalnerven des Rumpfes gleichgesetzt — Vorstellungen, die vor allem gegen Ende des 19. Jh. auf massive Ablehnung stießen. Die moderne Entwicklungsbiologie zei gt jedoch, dass zumindest Teile des Kopfes in ihrer Entwicklung eine deutliche Segmentierung aufweisen.

  1. Videobasierte Systeme

    NASA Astrophysics Data System (ADS)

    Knoll, Peter

    Videosensoren spielen für Fahrerassistenz systeme eine zentrale Rolle, da sie die Interpretation visueller Informationen (Objektklassifikation) gezielt unterstützen. Im Heckbereich kann die Video sensorik in der einfachsten Variante die ultraschallbasierte Einparkhilfe bei Einpark- und Rangiervorgängen unterstützen. Beim Nachtsichtsystem NightVision wird das mit Infrarotlicht angestrahlte Umfeld vor dem Fahrzeug mit einer Frontkamera aufgenommen und im Fahrzeugcockpit auf einem Display dem Fahrer angezeigt (s. Nachtsichtsysteme). Andere Fahrerassistenzsysteme verarbeiten die Videosignale und generieren daraus gezielt Informationen, die für eigenständige Funktionen (z. B. Spurverlassenswarner) oder aber als Zusatzinformation für andere Funktionen ausgewertet werden (Sensordatenfusion).

  2. Getreide, Brot und Feine Backwaren

    NASA Astrophysics Data System (ADS)

    von Grabowski, Hans-Uwe; Rolfe, Birgit

    Getreide und Getreideerzeugnisse sind ebenso wie Brot und Feine Backwaren nach dem Lebensmittel- und Futtermittel-Gesetzbuch (LFGB) [1] Lebensmittel im Sinne des Artikels 2 der VO (EG) Nr. 178/2002 (BasisVO) (s. auch Kap. 1.6/2.4.1/3.2). Gesetzlich festgelegte Begriffsbestimmungen gibt es für diese Lebensmittel nicht. Man muss sich daher allgemeiner Verkehrsauffassungen bedienen, wie sie von der Deutschen Lebensmittelbuch-Kommission in Form von Leitsätzen erarbeitet und veröffentlicht wurden [2]. Der Gesundheitsschutz und der Schutz des Verbrauchers vor Täuschung sind in der Basis-VO und dem LFGB geregelt.

  3. Ein stochastisches Modell zur Beschreibung von Signalen in digitalen Schaltungen basierend auf quadratischer Optimierung

    NASA Astrophysics Data System (ADS)

    Kleeberger, V. B.; Maier, P.; Schlichtmann, U.

    2013-07-01

    Die kontinuierlich fortschreitende Miniaturisierung in integrierten Schaltungen führt zu einem erhöhten Modellierungsbedarf verschiedenster Effekte, wie z.B. Alterung oder Stromverbrauch. Diese hängen von den auftretenden Signalen innerhalb der Schaltung ab, wodurch deren statistische Modellierung ein zentrales Problem darstellt. Dieser Beitrag stellt eine neue Methode zur stochastischen Signalmodellierung basierend auf quadratischer Optimierung vor. Die Methode wird mit Hilfe von realen Daten mit existierenden Ansätzen verglichen. Die Testergebnisse zeigen hierbei im vorgestellten Modell einen Genauigkeitszuwachs von bis zu einem Faktor 10 im Vergleich zu bereits existierenden Modellen.

  4. Unidirectional abnormal eye movement without gaze nystagmus - Report of a case.

    PubMed

    Mizuno, Masahiro; Shibasaki, Osamu; Shindo, Susumu; Ito, Akinori; Kase, Yasuhiro

    2016-06-01

    We report here a case with unidirectional abnormalities of smooth eye movements without gaze nystagmus. Abnormalities of eye movements were confined to unidirectional (leftward) horizontal pursuit and slow phase of OKN; however, horizontal VOR (slow phase of caloric nystagmus) and saccade were normal, and vertical eye movements were also normal. No lesions were detected in the central nervous system, and any history of drug intake was denied. Although the cause of the unidirectional abnormality in eye movement of this case is still not clear, a congenital origin seems to be the most probable. PMID:26386498

  5. Ländliche Entwicklung durch erneuerbare Energien - Das Beispiel Photovoltaik in Niederbayern

    NASA Astrophysics Data System (ADS)

    Zink, Roland

    2013-09-01

    Der Ausbau erneuerbarer Energien ist in Deutschland eine zentrale und politisch konsensfähige Forderung, um die Energieversorgung klimafreundlich und nachhaltig zu gestalten. Speziell ländliche Regionen rücken dabei in den Fokus, bieten sie doch aufgrund ihrer hohen Flächenverfügbarkeit große Potenziale für die flächenintensiven dezentralen Energieformen. Folglich erkennen Kommunen zunehmend das Entwicklungspotenzial dieser Technologien und sehen sie auch als Chance, neue wirtschaftliche Impulse vor Ort zu setzen. Der Beitrag skizziert die rasante Entwicklung der Photovoltaik im Regierungsbezirk Niederbayern und diskutiert anhand des Beispiels die Folgen für eine nachhaltige Regionalentwicklung.

  6. Required distribution of noise sources for Green's function recovery in diffusive fields

    NASA Astrophysics Data System (ADS)

    Shamsalsadati, S.; Weiss, C. J.

    2011-12-01

    In the most general sense, noise is the part of the signal of little or no interest, due to a multitude of reasons such as operator error, imperfect instrumentation, experiment design, or inescapable background interference. Considering the latter, it has been shown that Green's function can be extracted from cross-correlation of the ambient, diffusive wavefields arising from background random noise sources. Pore pressure and low-frequency electromagnetic induction are two such examples of diffusive fields. In theory, applying Green's function method in geophysical exploration requires infinity of volumetrically distributed sources; however, in the real world the number of noise sources in an area is limited, and furthermore, unevenly distributed in time, space and spectral content. Hence, quantification of the requisite noise sources that enable us to calculate Green's function acceptably well remains an open research question. The purpose of this study is to find the area of noise sources that contribute most to the Green's function estimation in diffusive systems. We call such a region the Volume of Relevance (VoR). Our analysis builds upon recent work in 1D homogeneous system where it was shown that sources located between two receivers positions are the most important ones for the purpose of Green's function recovery. Our results confirm the previous finding but we also examine the effect of heterogeneity, dimensionality and receiver location in both 1D and 2D at a fixed frequency. We demonstrate that for receivers located symmetrically across an interface between regions of contrasting diffusivity, the VoR rapidly shifts from one side of the interface to the other, and back again, as receiver separation increases. We also demonstrate that where the receiver pair is located on the interface itself, the shifting is less rapid, and for moderate to high diffusivity contrasts, the VoR remains entirely on the more diffusive side. In addition, because classical

  7. Supraleitung und Interkontinentalraketen „On-line computing“ zwischen Militär, Industrie und Wissenschaft

    NASA Astrophysics Data System (ADS)

    Knolle, Johannes; Joas, Christian

    Der zweite Weltkrieg und der Kalte Krieg veränderten nicht nur das Verhältnis zwischen Militär, Industrie und Wissenschaft, sondern auch die wissenschaftliche Praxis von Physikern und anderen Wissenschaftlern. In den 1950er Jahren stellte die Entwicklung von Interkontinentalraketen die Auftragnehmer des Militärs in der Industrie vor komplexe Fragestellungen, zu deren Lösung sie auf die Expertise von Wissenschaftlern angewiesen waren. Industrieunternehmen gründeten eigene Forschungseinheiten zur Lösung technischer und wissenschaftlicher Probleme.

  8. Effects of body orientation and rotation axis on pitch visual-vestibular interaction

    NASA Technical Reports Server (NTRS)

    Clement, G.; Wood, S. J.; Lathan, C. E.; Peterka, R. J.; Reschke, M. F.

    1999-01-01

    Spatial transformations of the vestibular-optokinetic system must account for changes in head position with respect to gravity in order to produce compensatory oculomotor responses. The purpose of this experiment was to study the influence of gravity on the vestibulo-ocular reflex (VOR) in darkness and on visual-vestibular interaction in the pitch plane in human subjects using two different comparisons: (1) Earth-horizontal axis (EHA) rotation about an upright versus a supine body orientation, and (2) Earth-horizontal versus Earth-vertical (EVA) rotation axes. Visual-vestibular responses (VVR) were evaluated by measuring the slow phase velocity of nystagmus induced during sinusoidal motion of the body in the pitch plane (at 0.2 Hz and 0.8 Hz) combined with a constant-velocity vertical optokinetic stimulation (at +/- 36 degrees/s). The results showed no significant effect on the gain or phase of the VOR in darkness or on the VVR responses at 0.8 Hz between EHA upright and EHA supine body orientations. However, there was a downward shift in the VOR bias in darkness in the supine orientation. There were systematic changes in VOR and VVR between EHA and EVA for 0.2 Hz, including a reduced modulation gain, increased phase lead, and decreased bias during EVA rotation. The same trend was also observed at 0.8 Hz, but at a lesser extent, presumably due to the effects of eccentric rotation in our EVA condition and/or to the different canal input across frequencies. The change in the bias at 0.2 Hz between rotation in darkness and rotation with an optokinetic stimulus was greater than the optokinetic responses without rotation. During EHA, changes in head position relative to gravity preserve graviceptor input to the VVR regardless of body orientation. However, the modifications in VVR gain and phase when the rotation axis is aligned with gravity indicate that this graviceptive information is important for providing compensatory eye movements during visual

  9. Empirical Green's function estimation for lossy systems: analysis of the volume of relevance for the origin of ambient fluctuations

    NASA Astrophysics Data System (ADS)

    Shamsalsadati, Sharmin; Weiss, Chester J.

    2012-09-01

    From a theoretical perspective, perfect Green's function recovery in diffusive systems is based on cross-correlation of time-series measured at distinct locations arising from background fluctuations from an infinite set of uncorrelated sources, either naturally occurring or engineered. Clearly such a situation is impossible in practice, and a relevant question to ask, then, is how does an imperfect set of noise sources affect the quality of the resulting empirical Green's function (EGF)? We narrow down this broad question by exploring the effect of source location and make no distinction between whether the noise sources are natural or man made. Following the theory of EGF recovery, the only requirement is that the sources are uncorrelated and endowed with the same (or nearly so) frequency spectrum and amplitude. As such, our intuition suggests that noise sources proximal to the observation points are likely to contribute more to the Green's function estimate than distal ones. However, in what manner and over what spatial extent our intuition is less clear. Thus, in this short note we specifically ask the question, 'Where are the noise sources that contribute most to the Green's function estimate in heterogeneous, lossy systems?' We call such a region the volume of relevance (VoR). Our analysis builds upon recent work on 1-D homogeneous systems by examining the effect of heterogeneity, dimensionality and receiver location in both one and two dimensions. Following the strategy of previous work in the field, the analysis is conducted out of mathematical convenience in the frequency domain although we stress that the sources need not be monochromatic. We find that for receivers located symmetrically across an interface between regions of contrasting diffusivity, the VoR rapidly shifts from one side of the interface to the other, and back again, as receiver separation increases. For the case where the receiver pair is located on the interface itself, the shifting is

  10. Messung und Analyse

    NASA Astrophysics Data System (ADS)

    Bathelt, Hartmut; Scheinhardt, Michael; Sell, Hendrik; Sottek, Roland; Guidati, Sandro; Helfer, Martin

    Für die Beurteilung von Akustik und Fahrkomfort eines Fahrzeugs gilt in der Fahrzeugentwicklung immer noch der alte Grundsatz: "Der Kunde fährt nicht am Prüfstand, sondern auf der Straße“. Daher werden Gesamtbeurteilungen des Entwicklungsstandes und Konkurrenzvergleiche (Benchmarking) nach wie vor auf der Straße durchgeführt, meist auf ausgewählten Fahrbahnen am Prüfgelände oder im Rahmen der regelmäßigen Winter- und Sommererprobungen unter extremen Witterungsverhältnissen.

  11. "Agnatha", Kieferlose

    NASA Astrophysics Data System (ADS)

    Rieger, Gunde; Maier, Wolfgang

    An der Basis der Wirbeltiere standen kieferlose Organismen, vermutlich mit Kiemendarm und noch filtrierender Lebensweise. Ihre wenigen heute noch lebenden Nachkommen sind die Myxinoida (Schleimaale) und die Petromyzontida (Neunaugen). Beide Taxa sind nur Relikte einer Vielzahl und Vielfalt im frühen Paläozoikum (Ordovizium bis ins Devon: vor 470-355 Mio. Jahren). Fossil traten die beiden heute lebenden Gruppen bereits im Karbon bzw. im Oberdevon auf. Obwohl diese rezenten Formen hoch spezialisiert sind, ermöglichen sie — zusammen mit den fossilen kieferlosen Formen (früher "†Ostracodermata") — Struktur und Lebensweise der frühen Craniota in Umrissen zu erkennen.

  12. Mathematik semantologisch verstehen

    NASA Astrophysics Data System (ADS)

    Wille, Rudolf

    Um zu verstehen, was Mathematik ist und bedeutet, reicht es nicht aus, mathematisches Denken und Wissen vielseitig zu erwerben. Hinzukommen muss stets ein angemessenes Verständnis der jeweiligen Bedeutungen mathematischer Denkformen, die in der aktual-realen Welt wirksam werden können. Beim Mathematik-Verstehen sollte es vor allem um ein Vermitteln des Selbstverständnisses der Mathematik, um ein Reflektieren des Bezugs der Mathematik zur realen Welt und um ein Beurteilen von Sinn, Bedeutung und Zusammenhang des Mathematischen in der Welt gehen.

  13. Adaptive Cruise Control (ACC)

    NASA Astrophysics Data System (ADS)

    Reif, Konrad

    Die adaptive Fahrgeschwindigkeitsregelung (ACC, Adaptive Cruise Control) ist eine Weiterentwicklung der konventionellen Fahrgeschwindigkeitsregelung, die eine konstante Fahrgeschwindigkeit einstellt. ACC überwacht mittels eines Radarsensors den Bereich vor dem Fahrzeug und passt die Geschwindigkeit den Gegebenheiten an. ACC reagiert auf langsamer vorausfahrende oder einscherende Fahrzeuge mit einer Reduzierung der Geschwindigkeit, sodass der vorgeschriebene Mindestabstand zum vorausfahrenden Fahrzeug nicht unterschritten wird. Hierzu greift ACC in Antrieb und Bremse ein. Sobald das vorausfahrende Fahrzeug beschleunigt oder die Spur verlässt, regelt ACC die Geschwindigkeit wieder auf die vorgegebene Sollgeschwindigkeit ein (Bild 1). ACC steht somit für eine Geschwindigkeitsregelung, die sich dem vorausfahrenden Verkehr anpasst.

  14. Entwicklung und Evaluation einer Kalibrierungsmethode für 3D-Ultraschall

    NASA Astrophysics Data System (ADS)

    Bergmeir, Christoph; Seitel, Mathias; Frank, Christian; de Simone, Raffaele; Meinzer, Hans-Peter; Wolf, Ivo

    Wir stellen eine Methode zur Kalibrierung einer 3D-Ultraschallsonde vor. Für Anwendungen in der minimalinvasiven Chirurgie wird die Ultraschallsonde mit einem Trackingsystem verbunden, um dem Aufnahmevolumen eine definierte räumliche Lage zu geben. Die Kalibrierung bringt die Koordinatensysteme des Trackingsystems und des Ultraschallbildes zur Deckung. Hierzu wird ein bekanntes Objekt, das Phantom, aufgenommen und im Ultraschallbild lokalisiert. Die Kalibrierungstransformation wird dann durch ein Verfahren der Hand-Auge-Kalibrierung errechnet. Ein oft übliches Anbringen zusätzlicher Trackingssensoren am Phantom ist damit nicht nötig, was die Kalibrierungsprozedur vereinfacht.

  15. [Vestibular compensation studies]. [Vestibular Compensation and Morphological Studies

    NASA Technical Reports Server (NTRS)

    Perachio, Adrian A. (Principal Investigator)

    1996-01-01

    The following topics are reported: neurophysiological studies on MVN neurons during vestibular compensation; effects of spinal cord lesions on VNC neurons during compensation; a closed-loop vestibular compensation model for horizontally canal-related MVN neurons; spatiotemporal convergence in VNC neurons; contributions of irregularly firing vestibular afferents to linear and angular VOR's; application to flight studies; metabolic measures in vestibular neurons; immediate early gene expression following vestibular stimulation; morphological studies on primary afferents, central vestibular pathways, vestibular efferent projection to the vestibular end organs, and three-dimensional morphometry and imaging.

  16. Beschallungstechnik, Beschallungsplanung und Simulation

    NASA Astrophysics Data System (ADS)

    Ahnert, Wolfgang; Goertz, Anselm

    Die primäre Aufgabe einer Lautsprecheranlage ist es, Musik, Sprache oder auch Signaltöne und Geräusche wiederzugeben. Diese können von einem Tonträger kommen (CD, Sprachspeicher), von einem anderen Ort übertragen (Zuspielung über Radio, TV, Telefon) oder vor Ort erzeugt werden. Letzteres umfasst Konzerte, Ansprachen, Durchsagen oder künstlerische Darbietungen, bei denen es meist darum geht, eine bereits vorhandene Quelle einer größeren oder weiter verteilten Anzahl von Personen zugänglich zu machen.

  17. Relation of motion sickness susceptibility to vestibular and behavioral measures of orientation

    NASA Technical Reports Server (NTRS)

    Peterka, Robert J.

    1995-01-01

    The objective is to determine the relationship of motion sickness susceptibility to vestibulo-ocular reflexes (VOR), motion perception, and behavioral utilization of sensory orientation cues for the control of postural equilibrium. The work is focused on reflexes and motion perception associated with pitch and roll movements that stimulate the vertical semicircular canals and otolith organs of the inner ear. This work is relevant to the space motion sickness problem since 0 g related sensory conflicts between vertical canal and otolith motion cues are a likely cause of space motion sickness.

  18. The Modified Ampullar Approach for Vestibular Implant Surgery: Feasibility and Its First Application in a Human with a Long-Term Vestibular Loss

    PubMed Central

    van de Berg, Raymond; Guinand, Nils; Guyot, Jean-Philippe; Kingma, Herman; Stokroos, Robert J.

    2012-01-01

    Objective: To assess, for the first time in a human with a long-term vestibular loss, a modified approach to the ampullae and the feasibility of evoking a VOR by ampullar stimulation. Materials and methods: Peroperative stimulation of the ampullae, using the ampullar approach, was performed under full anesthesia during cochlear implantation in a 21-year-old female patient, who had experienced bilateral vestibular areflexia and sensorineural hearing loss for almost 20 years. Results: The modified ampullar approach was performed successfully with as minimally invasive surgery as possible. Ampullar stimulation evoked eye movements containing vectors congruent with the stimulated canal. As expected, the preliminary electrophysiological data were influenced by the general anesthesia, which resulted in current spread and reduced maximum amplitudes of eye movement. Nevertheless, they confirm the feasibility of ampullar stimulation. Conclusion: The modified ampullar approach provides safe access to the ampullae using as minimally invasive surgery as possible. For the first time in a human with long-term bilateral vestibular areflexia, it is shown that the VOR can be evoked by ampullar stimulation, even when there has been no vestibular function for almost 20 years. This approach should be considered in vestibular surgery, as it provides safe access to one of the most favorable stimulus locations for development of a vestibular implant. PMID:22363317

  19. Azole susceptibility of Malassezia pachydermatis and Malassezia furfur and tentative epidemiological cut-off values.

    PubMed

    Cafarchia, Claudia; Iatta, Roberta; Immediato, Davide; Puttilli, Maria Rita; Otranto, Domenico

    2015-09-01

    This study aims to determine the minimal inhibitory concentration (MIC) distribution and the epidemiological cut-off values (ECVs) of Malassezia pachydermatis and Malassezia furfur isolates for fluconazole (FLZ), itraconazole (ITZ), posaconazole (POS), and voriconazole (VOR). A total of 62 M. pachydermatis strains from dogs with dermatitis and 78 M. furfur strains from humans with bloodstream infections (BSI) were tested by a modified broth microdilution Clinical and Laboratory Standards Institute (CLSI) method. ITZ and POS displayed lower MICs than VOR and FLZ, regardless of the Malassezia species. The MIC data for azoles of M. pachydermatis were four two-fold dilutions lower than those of M. furfur. Based on the ECVs, about 94% of Malassezia strains might be categorized within susceptible population for all azoles, except for FLZ, and azole cross-resistance was detected in association with FLZ in M. pachydermatis but not in M. furfur.The study proposes, for the first time, tentative azole ECVs for M. pachydermatis and M. furfur for monitoring the emergence of isolates with decreased susceptibilities and shows that the azole MIC distribution varied according to the Malassezia species tested, thus suggesting the usefulness of determining the susceptibility profile for effective treatment of each species. PMID:26162472

  20. Dynamics of the human linear vestibulo-ocular reflex at medium frequency and modification by short-term training

    NASA Technical Reports Server (NTRS)

    Shelhamer, M.; Roberts, D. C.; Zee, D. S.

    2000-01-01

    We study here the effect of a short-term training paradigm on the gain and phase of the human translational VOR (the linear VOR: LVOR). Subjects were exposed to lateral sinusoidal translations on a sled, at 0.5 Hz, 0.3 g peak acceleration. With subjects tracking a remembered target at 1.2 m, the LVOR (slow-phase) under these conditions typically has a phase lead or lag, and a gain that falls short of compensatory. To induce short-term adaptation (training), we presented an earth-fixed visual scene at 1.2 m during sinusoidal translation (x 1 viewing) for 20 minutes, so as to drive the LVOR toward compensatory phase and gain. We examined both the slow-phase and the saccadic responses to these stimuli. Testing after training showed changes in slow-component gain and phase which were mostly but not always in the compensatory direction. These changes were more consistent in naive subjects than in subjects who had previous LVOR experience. Changes in gain were seen with step as well as sinusoidal test stimuli; gain changes were not correlated with vergence changes. There was a strong correlation between gain changes and phase changes across subjects. Fast phases (catch-up saccades) formed a large component of the LVOR under our testing conditions (approximately 30% of the changes in gain but not in phase due to training.

  1. Visual/vestibular effects of inert gas narcosis.

    PubMed

    Hamilton, K; Laliberte, M F; Heslegrave, R; Khan, S

    1993-08-01

    Divers breathing compressed air at depths beyond 30 m experience a type of behavioural impairment known as inert gas narcosis. This condition degrades performance on a wide range of tasks and has the potential to compromise safety. Symptoms associated with narcosis include slowed response time, amnesia, and euphoria. Studies have also found disturbances to mechanisms regulating ocular control in response to vestibular stimulation; however, these experiments have been limited to very low frequency head movement (0.2 Hz). Thus, to further examine the effects of narcosis on visual/vestibular mechanisms, the vestibular ocular reflex (VOR) was assessed across a range of higher frequencies more representative of natural head movement (2.0-4.7 Hz). Seven subjects were tested prior to, during and after exposure to narcosis which was induced using 30% nitrous oxide. Standard room air was breathed as a control. The results indicated that narcosis decreased the velocity of compensatory eye movements in response to head rotation (decrease in VOR-gain), with more pronounced decreases occurring at the higher frequencies. The lag between eye and head position (phase lag) was also decreased by nitrous oxide; an effect that was again more pronounced at higher frequencies. These results indicate that narcosis disrupts ocular regulatory mechanisms which help to stabilize images on the retina during head movement. PMID:8365388

  2. Einleitung

    NASA Astrophysics Data System (ADS)

    Bertsche, Bernd; Gäng, Jochen

    In der Standortdebatte wird als Argument für den Wirtschaftsstandort Deutschland vor allem die hohe Qualität der hier entwickelten und erzeugten Produkte angeführt. Ein wesentlicher Aspekt der Qualität eines Produktes stellt dessen Funktionsfähigkeit - dessen Zuverlässigkeit - dar. Die Zuverlässigkeit eines Produktes beeinflusst somit wesentlich die Kaufentscheidungen der Nutzer, da diese neben hoher Funktionalität bei geringen Kosten vor allem eine hohe Zuverlässigkeit der Produkte erwarten. Allerdings ist in den letzten Jahren eine deutlich sinkende Zuverlässigkeit festzustellen. Nahezu jeder Kunde ist mit Unzuverlässigkeiten konfrontiert. Aufgrund der Zunahme von mechatronischen Systemen und dadurch folgend steigende Funktionalitäten, Komplexitäten sowie neueren innovativen Technologien bedarf es einer sorgfältigen Untersuchung, Fortentwicklung und innerbetrieblichen Integration der Datenbasis und ganzheitlicher, domänenübergreifender Methoden, die die Produktzuverlässigkeit sicherstellen und damit die hohe Nutzerzufriedenheit gewährleisten. Fehler in der Gestaltung von Produkten und Prozessen können sich unter Umständen gravierend auf die Zuverlässigkeit eines technischen Systems auswirken.

  3. Quantification of vestibular-induced eye movements in zebrafish larvae

    PubMed Central

    2010-01-01

    Background Vestibular reflexes coordinate movements or sensory input with changes in body or head position. Vestibular-evoked responses that involve the extraocular muscles include the vestibulo-ocular reflex (VOR), a compensatory eye movement to stabilize retinal images. Although an angular VOR attributable to semicircular canal stimulation was reported to be absent in free-swimming zebrafish larvae, recent studies reveal that vestibular-induced eye movements can be evoked in zebrafish larvae by both static tilts and dynamic rotations that tilt the head with respect to gravity. Results We have determined herein the basis of sensitivity of the larval eye movements with respect to vestibular stimulus, developmental stage, and sensory receptors of the inner ear. For our experiments, video recordings of larvae rotated sinusoidally at 0.25 Hz were analyzed to quantitate eye movements under infrared illumination. We observed a robust response that appeared as early as 72 hours post fertilization (hpf), which increased in amplitude over time. Unlike rotation about an earth horizontal axis, rotation about an earth vertical axis at 0.25 Hz did not evoke eye movements. Moreover, vestibular-induced responses were absent in mutant cdh23 larvae and larvae lacking anterior otoliths. Conclusions Our results provide evidence for a functional vestibulo-oculomotor circuit in 72 hpf zebrafish larvae that relies upon sensory input from anterior/utricular otolith organs. PMID:20815905

  4. Sterilisation

    NASA Astrophysics Data System (ADS)

    Ha, Suk-Woo; Koller, Michael; Göllner, Gerald

    Ein steriles Medizinprodukt ist frei von lebensfähigen Mikroorganismen. Von den internationalen Normen, die Anforderungen an die Validierung und Routineüberwachung von Sterilisationsverfahren festlegen, wird für sterile Medizinprodukte verlangt, dass jede zufällige mikrobielle Kontamination eines Medizinproduktes bereits vor der Sterilisation so gering wie möglich gehalten werden soll. Dennoch können auch Medizinprodukte, die unter üblichen Herstellungsbedingungen in Übereinstimmung mit den Anforderungen an Qualitätssicherungssysteme gefertigt oder die im Zuge in einer Einrichtung des Gesundheitswesens einem Reinigungsverfahren unterzogen wurden, vor der Sterilisation mit Mikroorganismen, wenn auch in geringen Anzahl, behaftet sein. Mittels Inaktivierung der mikrobiellen Kontamination können diese unsterilen Produkte in den sterilen Zustand überführt werden. Die Zeit, die für die Inaktivierung einer Reinkultur von Mikroorganismen mit physikalischen oder chemischen Mitteln, die bei der Sterilisation von Medizinprodukten eingesetzt werden, wird durch eine exponentielle Beziehung zwischen der Anzahl der überlebenden Mikroorganismen und dem Umfang der Behandlung mit dem Sterilisiermittel beschrieben.

  5. Relation between perception of vertical axis rotation and vestibulo-ocular reflex symmetry

    NASA Technical Reports Server (NTRS)

    Peterka, Robert J.; Benolken, Martha S.

    1991-01-01

    Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in the subject's perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function which could be of either central or peripheral origin. Deviations from perfect vestibulocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. Researchers looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflective and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests on the same subjects of both perceptual bias and VOR symmetry were well correlated.

  6. A dynamic model of the eye nystagmus response to high magnetic fields

    NASA Astrophysics Data System (ADS)

    Glover, Paul M.; Li, Yan; Antunes, Andre; Mian, Omar S.; Day, Brian L.

    2014-02-01

    It was recently shown that high magnetic fields evoke nystagmus in human subjects with functioning vestibular systems. The proposed mechanism involves interaction between ionic currents in the endolymph of the vestibular labyrinth and the static magnetic field. This results in a Lorentz force that causes endolymph flow to deflect the cupulae of the semi-circular canals to evoke a vestibular-ocular reflex (VOR). This should be analogous to stimulation by angular acceleration or caloric irrigation. We made measurements of nystagmus slow-phase velocities in healthy adults experiencing variable magnetic field profiles of up to 7 T while supine on a bed that could be moved smoothly into the bore of an MRI machine. The horizontal slow-phase velocity data were reliably modelled by a linear transfer function incorporating a low-pass term and a high-pass adaptation term. The adaptation time constant was estimated at 39.3 s from long exposure trials. When constrained to this value, the low-pass time constant was estimated at 13.6 ± 3.6 s (to 95% confidence) from both short and long exposure trials. This confidence interval overlaps with values obtained previously using angular acceleration and caloric stimulation. Hence it is compatible with endolymph flow causing a cupular deflection and therefore supports the hypothesis that the Lorentz force is a likely transduction mechanism of the magnetic field-evoked VOR.

  7. Measurement of the vestibulo-ocular reflex by magnetometry during active head movement.

    PubMed

    Aldren, C P; FitzGerald, J E; Kelly, P; Birchall, J P; Murray, A

    1996-10-01

    A new method of measuring the vestibulo-ocular reflex (VOR) during active head movements is presented. Subjects sat and attempted to maintain their gaze upon a fixed point whilst turning their heads from side to side in response to an auditory cue, to attain frequencies of head rotation that increased from 1 Hz to 4 Hz during a 24 s period. Head movements were monitored by a small magnetic field detector worn on the subject's forehead and positioned a set distance from a magnetic field transmitter coil. Eye movements were monitored using the corneo-retinal potential. Gain (eye angle/head angle) and phase difference (eye phase-head phase) were calculated to define the VOR. Three repeat measurements were made on 20 normal subjects. Gain decreased significantly (P < 0.0001) with increasing frequency whilst the phase difference remained unchanged. The 95% prediction intervals were narrow for both gain (+/- 0.28) and phase (+/- 11 degrees). These data, together with the speed and ease of performance of the test, suggest that the test can provide valuable information on the performance of the vestibular system. PMID:8922697

  8. Next Generation Life Support Project Status

    NASA Technical Reports Server (NTRS)

    Barta, Daniel J.; Chullen, Cinda; Vega, Leticia; Cox, Marlon R.; Aitchison, Lindsay T.; Lange, Kevin E.; Pensinger, Stuart J.; Meyer, Caitlin E.; Flynn, Michael; Jackson, W. Andrew; Abney, Morgan B.; Wheeler, Raymond M.

    2014-01-01

    Next Generation Life Support (NGLS) is one of over twenty technology development projects sponsored by NASA's Game Changing Development Program. The NGLS Project develops selected life support technologies needed for humans to live and work productively in space, with focus on technologies for future use in spacecraft cabin and space suit applications. Over the last three years, NGLS had five main project elements: Variable Oxygen Regulator (VOR), Rapid Cycle Amine (RCA) swing bed, High Performance (HP) Extravehicular Activity (EVA) Glove, Alternative Water Processor (AWP) and Series-Bosch Carbon Dioxide Reduction. The RCA swing bed, VOR and HP EVA Glove tasks are directed at key technology needs for the Portable Life Support System (PLSS) and pressure garment for an Advanced Extravehicular Mobility Unit (EMU). Focus is on prototyping and integrated testing in cooperation with the Advanced Exploration Systems (AES) Advanced EVA Project. The HP EVA Glove Element, new this fiscal year, includes the generation of requirements and standards to guide development and evaluation of new glove designs. The AWP and Bosch efforts focus on regenerative technologies to further close spacecraft cabin atmosphere revitalization and water recovery loops and to meet technology maturation milestones defined in NASA's Space Technology Roadmaps. These activities are aimed at increasing affordability, reliability, and vehicle self-sufficiency while decreasing mass and mission cost, supporting a capability-driven architecture for extending human presence beyond low-Earth orbit, along a human path toward Mars. This paper provides a status of current technology development activities with a brief overview of future plans.

  9. [Cerebellar Control of Ocular Movements: Application to the Topographical Diagnosis of Cerebellar Lesions].

    PubMed

    Hirose, Genjiro

    2016-03-01

    Over the last decade, substantial information on cerebellar oculomotor control has been provided by the use of sophisticated neuroanatomical, neurophysiological, and imaging techniques. We now know that an intact cerebellum is a prerequisite for normal oculomotor performance. This review clarifies the current knowledge on structure-function correlations of the cerebellum in relation to ocular movements and allows them to be applied to topographical diagnosis of cerebellar lesions. The cerebellar regions most closely related to oculomotor function are: (1) the flocculus/paraflocculus for VOR suppression, cancellation, smooth pursuit eye movement and gaze-holding, (2) the nodulus/ventral uvula for velocity storage and low frequency prolonged vestibular response, and (3) the dorsal oculomotor vermis (declive VI, folium VII) and the posterior portion of the fastigial nucleus (fastigial oculomotor region) for saccades and smooth pursuit initiation. Symptomatically, defects in the flocculus/parflocculus cause saccadic pursuit, downbeat nystagmus, and impairments to visual suppression of the VOR. Lesions of the nodulus/uvula reveal as periodic alternating nystagmus. Lesions of the oculomotor vermis and the fastigial nucleus can induce saccadic dysmetria, while fastigial nucleus lesions may also cause ocular flutter/opsoclonus. A detailed knowledge of cerebellar anatomy and the physiology of eye movements enables localization of lesions to specific areas of the cerebellum. PMID:27001776

  10. Revealing the effects of the El Niño-southern oscillation on tropical cyclone intensity over the western north pacific from a model sensitivity study

    NASA Astrophysics Data System (ADS)

    Zhou, Yang; Jiang, Jing; Lu, Youyu; Huang, Anning

    2013-07-01

    Five sets of model sensitivity experiments are conducted to investigate the influence of tropical cyclone (TC) genesis location and atmospheric circulation on interannual variability of TC intensity in the western North Pacific (WNP). In each experiment, bogus TCs are placed at different initial locations, and simulations are conducted with identical initial and boundary conditions. In the first three experiments, the specified atmospheric and SST conditions represent the mean conditions of El Niño, La Niña, and neutral years. The other two experiments are conducted with the specified atmospheric conditions of El Niño and La Niña years but with SSTs exchanged. The model results suggest that TCs generated in the southeastern WNP incurred more favorable environmental conditions for development than TCs generated elsewhere. The different TC intensities between El Niño and La Niña years are caused by difference in TC genesis location and low-level vorticity (VOR). VOR plays a significant role in the intensities of TCs with the same genesis locations between El Niño and La Niña years.

  11. Coordination of Lower Limb Joints During Locomotion: The Effects of Vestibulo-Ocular Reflex Adaptation

    NASA Technical Reports Server (NTRS)

    Miller, Chris; Mulavara, Ajitkumar; Richards, Jason; Peters, Brian; Houser, Jeremy; Marshburn, Ann; Bloomberg, Jacob

    2003-01-01

    Controlling locomotion while maintaining a stable gaze requires precise coordination between several, interdependent full-body sensorimotor subsystems (Bloomberg and Mulavara, 2003; McDonald, et al., 1997). The overall goal of this study is to determine how this full-body gaze stabilization system responds to adaptive changes in vestibuloocular reflex (VOR) function. Locomotion involves cyclical physical interactions (impacts) with the environment. Hence, focusing on a target and maintaining visual acuity during this activity may require mechanisms to manage the energy flow, so it does not disrupt the visual and vestibular sensory information processing that stabilizes gaze. It has been shown that increasing the difficulty of a gaze task (reading numbers on a screen as opposed to simply focusing on a central dot pattern) resulted in an increase in the amount of knee flexion movement during the critical phase immediately following the heel strike event (Mulavara and Bloomberg, 2003). The increase in knee flexion during the stance phase of the gait cycle has been suggested to function as a shock absorbing mechanism associated with the rapid weight transfer from the trailing to the leading leg during walking. To understand this full-body coordination, the relative contributions of each component and the resulting effects should be assessed. In this study, we hypothesized that VOR adaptation would result in a reorganization of the lower limb joint coordination during treadmill walking in a manner to facilitate the gaze stabilization task and preserve locomotor function.

  12. A Hydrogel-Based Hybrid Theranostic Contact Lens for Fungal Keratitis.

    PubMed

    Huang, Jian-Fei; Zhong, Jing; Chen, Guo-Pu; Lin, Zuan-Tao; Deng, Yuqing; Liu, Yong-Lin; Cao, Piao-Yang; Wang, Bowen; Wei, Yantao; Wu, Tianfu; Yuan, Jin; Jiang, Gang-Biao

    2016-07-26

    Fungal keratitis, a severe ocular disease, is one of the leading causes of ocular morbidity and blindness, yet it is often neglected, especially in developing countries. Therapeutic efficacy of traditional treatment such as eye drops is very limited due to poor bioavailability, whereas intraocular injection might cause serious side effects. Herein, we designed and fabricated a hybrid hydrogel-based contact lens which comprises quaternized chitosan (HTCC), silver nanoparticles, and graphene oxide (GO) with a combination of antibacterial and antifungal functions. The hydrogel is cross-linked through electrostatic interactions between GO and HTCC, resulting in strong mechanical properties. Voriconazole (Vor), an antifungal drug, can be loaded onto GO which retains the drug and promotes its sustained release from the hydrogel-based contact lenses. The contact lenses also exhibited good antimicrobial functions in view of glycidyltrimethylammonium chloride and silver nanoparticles. The results from in vitro and in vivo experiments demonstrate that contact lenses loaded with Vor have excellent efficacy in antifungal activity in vitro and could significantly enhance the therapeutic effects on a fungus-infected mouse model. The results indicate that this hydrogel contact lenses-based drug delivery system might be a promising therapeutic approach for a rapid and effective treatment of fungal keratitis. PMID:27244244

  13. Kinematic principles of primate rotational vestibulo-ocular reflex. I. Spatial organization of fast phase velocity axes

    NASA Technical Reports Server (NTRS)

    Hess, B. J.; Angelaki, D. E.

    1997-01-01

    The spatial organization of fast phase velocity vectors of the vestibulo-ocular reflex (VOR) was studied in rhesus monkeys during yaw rotations about an earth-horizontal axis that changed continuously the orientation of the head relative to gravity ("barbecue spit" rotation). In addition to a velocity component parallel to the rotation axis, fast phases also exhibited a velocity component that invariably was oriented along the momentary direction of gravity. As the head rotated through supine and prone positions, torsional components of fast phase velocity axes became prominent. Similarly, as the head rotated through left and right ear-down positions, fast phase velocity axes exhibited prominent vertical components. The larger the speed of head rotation the greater the magnitude of this fast phase component, which was collinear with gravity. The main sequence properties of VOR fast phases were independent of head position. However, peak amplitude as well as peak velocity of fast phases were both modulated as a function of head orientation, exhibiting a minimum in prone position. The results suggest that the fast phases of vestibulo-ocular reflexes not only redirect gaze and reposition the eye in the direction of head motion but also reorient the eye with respect to earth-vertical when the head moves relative to gravity. As further elaborated in the companion paper, the underlying mechanism could be described as a dynamic, gravity-dependent modulation of the coordinates of ocular rotations relative to the head.

  14. Oculomotor control of primary eye position discriminates between translation and tilt

    NASA Technical Reports Server (NTRS)

    Hess, B. J.; Angelaki, D. E.

    1999-01-01

    We have previously shown that fast phase axis orientation and primary eye position in rhesus monkeys are dynamically controlled by otolith signals during head rotations that involve a reorientation of the head relative to gravity. Because of the inherent ambiguity associated with primary otolith afferent coding of linear accelerations during head translation and tilts, a similar organization might also underlie the vestibulo-ocular reflex (VOR) during translation. The ability of the oculomotor system to correctly distinguish translational accelerations from gravity in the dynamic control of primary eye position has been investigated here by comparing the eye movements elicited by sinusoidal lateral and fore-aft oscillations (0.5 Hz +/- 40 cm, equivalent to +/- 0.4 g) with those during yaw rotations (180 degrees/s) about a vertically tilted axis (23.6 degrees). We found a significant modulation of primary eye position as a function of linear acceleration (gravity) during rotation but not during lateral and fore-aft translation. This modulation was enhanced during the initial phase of rotation when there was concomitant semicircular canal input. These findings suggest that control of primary eye position and fast phase axis orientation in the VOR are based on central vestibular mechanisms that discriminate between gravity and translational head acceleration.

  15. Inactivation of Semicircular Canals Causes Adaptive Increases in Otolith-driven Tilt Responses

    NASA Technical Reports Server (NTRS)

    Angelaki, Dora E.; Newlands, Shawn D.; Dickman, J. David

    2002-01-01

    Growing experimental and theoretical evidence suggests a functional synergy in the processing of otolith and semicircular canal signals for the generation of the vestibulo-ocular reflexes (VORs). In this study we have further tested this functional interaction by quantifying the adaptive changes in the otolith-ocular system during both rotational and translational movements after surgical inactivation of the semicircular canals. For 0.1- 0.5 Hz (stimuli for which there is no recovery of responses from the plugged canals), pitch and roll VOR gains recovered during earth- horizontal (but not earth-vertical) axis rotations. Corresponding changes were also observed in eye movements elicited by translational motion (0.1 - 5 Hz). Specifically, torsional eye movements increased during lateral motion, whereas vertical eye movements increased during fore-aft motion. The findings indicate that otolith signals can be adapted according to compromised strategy that leads to improved gaze stabilization during motion. Because canal-plugged animals permanently lose the ability to discriminate gravitoinertial accelerations, adapted animals can use the presence of gravity through otolith-driven tilt responses to assist gaze stabilization during earth-horizontal axis rotations.

  16. Datenintegration und Deduplizierung

    NASA Astrophysics Data System (ADS)

    Bleiholder, Jens; Schmid, Joachim

    In Unternehmen liegen viele Daten heutzutage immer seltener vollständig an einem einzigen physikalischen Ort vor, sondern sind weltweit verteilt. Dies liegt zum einen an der immer besser gewordenen Infrastruktur, die eine solche Verteilung auf einfache Art und Weise ermöglicht, und zum anderen an der Tatsache, dass viele Unternehmen weltweit tätig sind. So fallen Daten weltweit an, werden aber jeweils lokal - vor Ort - gespeichert. Daher müssen oft mehrere Datenquellen genutzt werden, um einen aktuellen, vollständigen und genauen Überblick über die vorhandenen Daten zu gewinnen. Datenintegration hilft, indem sie Daten aus mehreren Quellen zusammenführt und einheitlich darstellt. Diese integrierten Daten können genutzt werden, um sich einen Überblick über das Unternehmen zu verschaffen, z.B. wenn Unternehmen fusionieren und nur noch eine Kundendatenbank bestehen bleiben soll, oder wenn zu einem Kunden die Daten aus den verschiedenen Fachabteilungen zusammengeführt werden sollen. Anhand eines solchen Beispiels, der Integration von Kundendaten zu Kfz- und Lebensversicherungen erläutern wir im Folgenden einzelne Techniken.

  17. Relation between perception of vertical axis rotation and vestibulo-ocular reflex symmetry

    NASA Technical Reports Server (NTRS)

    Peterka, Robert J.; Benolken, Martha S.

    1992-01-01

    Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in the subject's perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function which could be of either central or peripheral origin. Deviations from perfect vestibulo-ocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. Researchers looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflective and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests on the same subjects of both perceptual bias and VOR symmetry were well correlated.

  18. Caspase inhibitors promote vestibular hair cell survival and function after aminoglycoside treatment in vivo

    NASA Technical Reports Server (NTRS)

    Matsui, Jonathan I.; Haque, Asim; Huss, David; Messana, Elizabeth P.; Alosi, Julie A.; Roberson, David W.; Cotanche, Douglas A.; Dickman, J. David; Warchol, Mark E.

    2003-01-01

    The sensory hair cells of the inner ear undergo apoptosis after acoustic trauma or aminoglycoside antibiotic treatment, causing permanent auditory and vestibular deficits in humans. Previous studies have demonstrated a role for caspase activation in hair cell death and ototoxic injury that can be reduced by concurrent treatment with caspase inhibitors in vitro. In this study, we examined the protective effects of caspase inhibition on hair cell death in vivo after systemic injections of aminoglycosides. In one series of experiments, chickens were implanted with osmotic pumps that administrated the pan-caspase inhibitor z-Val-Ala-Asp(Ome)-fluoromethylketone (zVAD) into inner ear fluids. One day after the surgery, the animals received a 5 d course of treatment with streptomycin, a vestibulotoxic aminoglycoside. Direct infusion of zVAD into the vestibule significantly increased hair cell survival after streptomycin treatment. A second series of experiments determined whether rescued hair cells could function as sensory receptors. Animals treated with streptomycin displayed vestibular system impairment as measured by a greatly reduced vestibulo-ocular response (VOR). In contrast, animals that received concurrent systemic administration of zVAD with streptomycin had both significantly greater hair cell survival and significantly increased VOR responses, as compared with animals treated with streptomycin alone. These findings suggest that inhibiting the activation of caspases promotes the survival of hair cells and protects against vestibular function deficits after aminoglycoside treatment.

  19. Three Dimensional Vestibular Ocular Reflex Testing Using a Six Degrees of Freedom Motion Platform

    PubMed Central

    Dits, Joyce; Houben, Mark M.J.; van der Steen, Johannes

    2013-01-01

    The vestibular organ is a sensor that measures angular and linear accelerations with six degrees of freedom (6DF). Complete or partial defects in the vestibular organ results in mild to severe equilibrium problems, such as vertigo, dizziness, oscillopsia, gait unsteadiness nausea and/or vomiting. A good and frequently used measure to quantify gaze stabilization is the gain, which is defined as the magnitude of compensatory eye movements with respect to imposed head movements. To test vestibular function more fully one has to realize that 3D VOR ideally generates compensatory ocular rotations not only with a magnitude (gain) equal and opposite to the head rotation but also about an axis that is co-linear with the head rotation axis (alignment). Abnormal vestibular function thus results in changes in gain and changes in alignment of the 3D VOR response. Here we describe a method to measure 3D VOR using whole body rotation on a 6DF motion platform. Although the method also allows testing translation VOR responses 1, we limit ourselves to a discussion of the method to measure 3D angular VOR. In addition, we restrict ourselves here to description of data collected in healthy subjects in response to angular sinusoidal and impulse stimulation. Subjects are sitting upright and receive whole-body small amplitude sinusoidal and constant acceleration impulses. Sinusoidal stimuli (f = 1 Hz, A = 4°) were delivered about the vertical axis and about axes in the horizontal plane varying between roll and pitch at increments of 22.5° in azimuth. Impulses were delivered in yaw, roll and pitch and in the vertical canal planes. Eye movements were measured using the scleral search coil technique 2. Search coil signals were sampled at a frequency of 1 kHz. The input-output ratio (gain) and misalignment (co-linearity) of the 3D VOR were calculated from the eye coil signals 3. Gain and co-linearity of 3D VOR depended on the orientation of the stimulus axis. Systematic deviations were

  20. Kinematic principles of primate rotational vestibulo-ocular reflex. II. Gravity-dependent modulation of primary eye position.

    PubMed

    Hess, B J; Angelaki, D E

    1997-10-01

    The kinematic constraints of three-dimensional eye positions were investigated in rhesus monkeys during passive head and body rotations relative to gravity. We studied fast and slow phase components of the vestibulo-ocular reflex (VOR) elicited by constant-velocity yaw rotations and sinusoidal oscillations about an earth-horizontal axis. We found that the spatial orientation of both fast and slow phase eye positions could be described locally by a planar surface with torsional variation of <2.0 +/- 0.4 degrees (displacement planes) that systematically rotated and/or shifted relative to Listing's plane. In supine/prone positions, displacement planes pitched forward/backward; in left/right ear-down positions, displacement planes were parallel shifted along the positive/negative torsional axis. Dynamically changing primary eye positions were computed from displacement planes. Torsional and vertical components of primary eye position modulated as a sinusoidal function of head orientation in space. The torsional component was maximal in ear-down positions and approximately zero in supine/prone orientations. The opposite was observed for the vertical component. Modulation of the horizontal component of primary eye position exhibited a more complex dependence. In contrast to the torsional component, which was relatively independent of rotational speed, modulation of the vertical and horizontal components of primary position depended strongly on the speed of head rotation (i.e., on the frequency of oscillation of the gravity vector component): the faster the head rotated relative to gravity, the larger was the modulation. Corresponding results were obtained when a model based on a sinusoidal dependence of instantaneous displacement planes (and primary eye position) on head orientation relative to gravity was fitted to VOR fast phase positions. When VOR fast phase positions were expressed relative to primary eye position estimated from the model fits, they were confined

  1. Neural processing of gravito-inertial cues in humans. II. Influence of the semicircular canals during eccentric rotation.

    PubMed

    Merfeld, D M; Zupan, L H; Gifford, C A

    2001-04-01

    All linear accelerometers, including the otolith organs, respond equivalently to gravity and linear acceleration. To investigate how the nervous system resolves this ambiguity, we measured perceived roll tilt and reflexive eye movements in humans in the dark using two different centrifugation motion paradigms (fixed radius and variable radius) combined with two different subject orientations (facing-motion and back-to-motion). In the fixed radius trials, the radius at which the subject was seated was held constant while the rotation speed was changed to yield changes in the centrifugal force. In variable radius trials, the rotation speed was held constant while the radius was varied to yield a centrifugal force that nearly duplicated that measured during the fixed radius condition. The total gravito-inertial force (GIF) measured by the otolith organs was nearly identical in the two paradigms; the primary difference was the presence (fixed radius) or absence (variable radius) of yaw rotational cues. We found that the yaw rotational cues had a large statistically significant effect on the time course of perceived tilt, demonstrating that yaw rotational cues contribute substantially to the neural processing of roll tilt. We also found that the orientation of the subject relative to the centripetal acceleration had a dramatic influence on the eye movements measured during fixed radius centrifugation. Specifically, the horizontal vestibuloocular reflex (VOR) measured in our human subjects was always greater when the subject faced the direction of motion than when the subjects had their backs toward the motion during fixed radius rotation. This difference was consistent with the presence of a horizontal translational VOR response induced by the centripetal acceleration. Most importantly, by comparing the perceptual tilt responses to the eye movement responses, we found that the translational VOR component decayed as the subjective tilt indication aligned with the tilt of

  2. Kinematic principles of primate rotational vestibulo-ocular reflex. II. Gravity-dependent modulation of primary eye position

    NASA Technical Reports Server (NTRS)

    Hess, B. J.; Angelaki, D. E.

    1997-01-01

    The kinematic constraints of three-dimensional eye positions were investigated in rhesus monkeys during passive head and body rotations relative to gravity. We studied fast and slow phase components of the vestibulo-ocular reflex (VOR) elicited by constant-velocity yaw rotations and sinusoidal oscillations about an earth-horizontal axis. We found that the spatial orientation of both fast and slow phase eye positions could be described locally by a planar surface with torsional variation of <2.0 +/- 0.4 degrees (displacement planes) that systematically rotated and/or shifted relative to Listing's plane. In supine/prone positions, displacement planes pitched forward/backward; in left/right ear-down positions, displacement planes were parallel shifted along the positive/negative torsional axis. Dynamically changing primary eye positions were computed from displacement planes. Torsional and vertical components of primary eye position modulated as a sinusoidal function of head orientation in space. The torsional component was maximal in ear-down positions and approximately zero in supine/prone orientations. The opposite was observed for the vertical component. Modulation of the horizontal component of primary eye position exhibited a more complex dependence. In contrast to the torsional component, which was relatively independent of rotational speed, modulation of the vertical and horizontal components of primary position depended strongly on the speed of head rotation (i.e., on the frequency of oscillation of the gravity vector component): the faster the head rotated relative to gravity, the larger was the modulation. Corresponding results were obtained when a model based on a sinusoidal dependence of instantaneous displacement planes (and primary eye position) on head orientation relative to gravity was fitted to VOR fast phase positions. When VOR fast phase positions were expressed relative to primary eye position estimated from the model fits, they were confined

  3. High-Speed Video-Oculography for Measuring Three-Dimensional Rotation Vectors of Eye Movements in Mice

    PubMed Central

    Takeda, Noriaki; Uno, Atsuhiko; Inohara, Hidenori; Shimada, Shoichi

    2016-01-01

    Background The mouse is the most commonly used animal model in biomedical research because of recent advances in molecular genetic techniques. Studies related to eye movement in mice are common in fields such as ophthalmology relating to vision, neuro-otology relating to the vestibulo-ocular reflex (VOR), neurology relating to the cerebellum’s role in movement, and psychology relating to attention. Recording eye movements in mice, however, is technically difficult. Methods We developed a new algorithm for analyzing the three-dimensional (3D) rotation vector of eye movement in mice using high-speed video-oculography (VOG). The algorithm made it possible to analyze the gain and phase of VOR using the eye’s angular velocity around the axis of eye rotation. Results When mice were rotated at 0.5 Hz and 2.5 Hz around the earth’s vertical axis with their heads in a 30° nose-down position, the vertical components of their left eye movements were in phase with the horizontal components. The VOR gain was 0.42 at 0.5 Hz and 0.74 at 2.5 Hz, and the phase lead of the eye movement against the turntable was 16.1° at 0.5 Hz and 4.88° at 2.5 Hz. Conclusions To the best of our knowledge, this is the first report of this algorithm being used to calculate a 3D rotation vector of eye movement in mice using high-speed VOG. We developed a technique for analyzing the 3D rotation vector of eye movements in mice with a high-speed infrared CCD camera. We concluded that the technique is suitable for analyzing eye movements in mice. We also include a C++ source code that can calculate the 3D rotation vectors of the eye position from two-dimensional coordinates of the pupil and the iris freckle in the image to this article. PMID:27023859

  4. Vestibuloocular reflex of the adult flatfish. III. A species-specific reciprocal pattern of excitation and inhibition.

    PubMed

    Graf, W; Spencer, R; Baker, H; Baker, R

    2001-09-01

    In juvenile flatfish the vestibuloocular reflex (VOR) circuitry that underlies compensatory eye movements adapts to a 90 degrees relative displacement of vestibular and oculomotor reference frames during metamorphosis. VOR pathways are rearranged to allow horizontal canal-activated second-order vestibular neurons in adult flatfish to control extraocular motoneurons innervating vertical eye muscles. This study describes the anatomy and physiology of identified flatfish-specific excitatory and inhibitory vestibular pathways. In antidromically identified oculomotor and trochlear motoneurons, excitatory postsynaptic potentials (EPSPs) were elicited after electrical stimulation of the horizontal canal nerve expected to provide excitatory input. Electrotonic depolarizations (0.8-0.9 ms) preceded small amplitude (<0.5 mV) chemical EPSPs at 1.2-1.6 ms with much larger EPSPs (>1 mV) recorded around 2.5 ms. Stimulation of the opposite horizontal canal nerve produced inhibitory postsynaptic potentials (IPSPs) at a disynaptic latency of 1.6-1.8 ms that were depolarizing at membrane resting potentials around -60 mV. Injection of chloride ions increased IPSP amplitude, and current-clamp analysis showed the IPSP equilibrium potential to be near the membrane resting potential. Repeated electrical stimulation of either the excitatory or inhibitory horizontal canal vestibular nerve greatly increased the amplitude of the respective synaptic responses. These observations suggest that the large terminal arborizations of each VOR neuron imposes an electrotonic load requiring multiple action potentials to maximize synaptic efficacy. GABA antibodies labeled axons in the medial longitudinal fasciculus (MLF) some of which were hypothesized to originate from horizontal canal-activated inhibitory vestibular neurons. GABAergic terminal arborizations were distributed largely on the somata and proximal dendrites of oculomotor and trochlear motoneurons. These findings suggest that the species

  5. General purpose algorithms for characterization of slow and fast phase nystagmus

    NASA Technical Reports Server (NTRS)

    Lessard, Charles S.

    1987-01-01

    In the overall aim for a better understanding of the vestibular and optokinetic systems and their roles in space motion sickness, the eye movement responses to various dynamic stimuli are measured. The vestibulo-ocular reflex (VOR) and the optokinetic response, as the eye movement responses are known, consist of slow phase and fast phase nystagmus. The specific objective is to develop software programs necessary to characterize the vestibulo-ocular and optokinetic responses by distinguishing between the two phases of nystagmus. The overall program is to handle large volumes of highly variable data with minimum operator interaction. The programs include digital filters, differentiation, identification of fast phases, and reconstruction of the slow phase with a least squares fit such that sinusoidal or psuedorandom data may be processed with accurate results. The resultant waveform, slow phase velocity eye movements, serves as input data to the spectral analysis programs previously developed for NASA to analyze nystagmus responses to pseudorandom angular velocity inputs.

  6. Vestibular efferent neurons project to the flocculus

    NASA Technical Reports Server (NTRS)

    Shinder, M. E.; Purcell, I. M.; Kaufman, G. D.; Perachio, A. A.

    2001-01-01

    A bilateral projection from the vestibular efferent neurons, located dorsal to the genu of the facial nerve, to the cerebellar flocculus and ventral paraflocculus was demonstrated. Efferent neurons were double-labeled by the unilateral injections of separate retrograde tracers into the labyrinth and into the floccular and ventral parafloccular lobules. Efferent neurons were found with double retrograde tracer labeling both ipsilateral and contralateral to the sites of injection. No double labeling was found when using a fluorescent tracer with non-fluorescent tracers such as horseradish peroxidase (HRP) or biotinylated dextran amine (BDA), but large percentages of efferent neurons were found to be double labeled when using two fluorescent substances including: fluorogold, microruby dextran amine, or rhodamine labeled latex beads. These data suggest a potential role for vestibular efferent neurons in modulating the dynamics of the vestibulo-ocular reflex (VOR) during normal and adaptive conditions.

  7. Halbautomatische Segmentierung von Pulmonalgefäßen in CT Daten als Referenz zur Validierung automatischer Verfahren

    NASA Astrophysics Data System (ADS)

    Kaftan, Jens N.; Bakai, Annemarie; Maier, Florian; Aach, Til

    Das Segmentieren von Pulmonalgefäßen in Computertomographie (CT) Daten wurde schon vielfach behandelt und wird z.B. bei der computerunterstützten Detektion von Lungenembolien angewendet. Vielen Segmentierverfahren fehlt jedoch eine quantitative Validierung aufgrund mangelnder Referenzsegmentierungen. Wir stellen ein System zur halbautomatischen Segmentierung von Blutgefäßen in definierten Bereichen der Lunge basierend auf dem Random-Walker-Algorithmus vor. Durch Initialisierung der Methode mittels automatisch generierter Saatpunkte wird die Effizienz des Verfahrens erhöht und die erforderliche Benutzerinteraktion reduziert. Die resultierenden Segmentierungen können zur Validierung von automatischen Verfahren verwendet werden. Exemplarisch evaluieren wir ein vollautomatisches Segmentierverfahren basierend auf dem Fuzzy-Connectedness-Algorithmus.

  8. Ein mobiler und offener Kernspintomograph: Kernspintomographie für Medizin und Materialforschung

    NASA Astrophysics Data System (ADS)

    Blümich, Bernhard; Kölker, Christian; Casanova, Federico; Perlo, Juan; Felder, Jörg

    2005-09-01

    An der RWTH Aachen wurde der erste offene und mobile Kernspintomograph entwickelt. Anders als die normalerweise riesigen und unbeweglichen Geräte besitzt er keine enge Magnetröhre. So kann er auch in große Untersuchungsobjekte hinein schauen, ohne dass diese zerstört werden müssen. Wie eine Lupe erfasst er dabei ein begrenztes Volumen um den Aufsatzpunkt herum. Neben der Medizin ermöglicht der offene Tomograph viele neue Anwendungsgebiete, vor allem in der Materialprüfung und Qualitätskontrolle. Der Aachener Prototyp kann auch das Fließprofil und die Geschwindigkeitsverteilung strömender Flüssigkeiten sichtbar machen. Sein offenes Prinzip erforderte neue technische Komponenten und modifizierte bildgebende Verfahren. Die Messzeit pro Bild kann heute schon unter einer Viertelstunde liegen.

  9. Dienstleistung Instandhaltung

    NASA Astrophysics Data System (ADS)

    Horn, Wolfgang

    Die gravierenden Veränderungen des Marktes und des Wettbewerbes infolge der Globalisierung Ende des 20. Jahrhunderts hatten auch einschneidende Auswirkungen auf die industrielle Instandhaltung. Dies galt sowohl für die unternehmensinterne Instandhaltung als auch für die externen Instandhaltungsdienstleister. Die Instandhaltung, die sich in der Vergangenheit schon ständig den sich verändernden wirtschaftlichen Rahmenbedingungen in der Regel auch erfolgreich angepasst hatte, stand vor einer neuen Herausforderung. Sie wurde erneut hinsichtlich ihrer Schnittstellen, Arbeitsteilung und Organisation sowie der Flexibilität, Qualität, Nachhaltigkeit und Gesamteffizienz in vielen Unternehmen sowohl intern als auch extern zunehmend sehr kritisch betrachtet. Es wurde in vielen Unternehmen prinzipiell alles auf den Prüfstand gestellt und bisherige Strukturen, Abläufe, Strategien und Prozesse hinsichtlich des vorhandenen Verbesserungspotenzials hinterfragt. Dabei wurde auch sehr oft über den "eigenen Tellerrand“ geschaut und externer Sachverstand genutzt.

  10. Sichtbeton Atlas

    NASA Astrophysics Data System (ADS)

    Schulz, Joachim

    Bereits 1960, d. h. vor 48 Jahren, hat der Architekt R. Probst einen Artikel verfasst mit dem Thema "Sichtbeton - eine Modetorheit". Er wollte mit diesem Beitrag bewusst provozieren und die Diskussion anregen, damit Architekten sich mehr mit dem Baustoff Sichtbeton auseinandersetzen, ihn kritischer bewerten, ihn bewusster und überlegter einsetzen. Trotz dieser schon damals vorhandenen Kritik an diesem Baustoff und dessen Verwendung, kam es in den 1960er und 1970er Jahren vermehrt zu "Bausünden" mit Sichtbeton. Die Welle der "Sichtbetonitis" kam über das Land und riss viele Planer mit sich. Das Lehrgeld wurde bezahlt. Seit den 1990er Jahren wird Sichtbeton wieder vermehrt von vielen Architekten und Bauherren als gestalterisches Mittel eingesetzt.

  11. Von der Prägeometrie zur Topologischen Komplexität.

    NASA Astrophysics Data System (ADS)

    Kurth, D.

    Der Autor macht in seinem Beitrag gegen das vorherrschende reduktionistische Selbstverständnis der modernen Physik geltend, daß eine umfassende Theorie von Allem (TOE) nicht schon durch eine Alles vereinheitlichende Theorie als Abschluß des reduktionistischen Programms der Elementarteilchenphysik gegeben sein kann. Zum einen muß der initialen Kontingenz unseres Universums durch eine entsprechende quantenkosmologische Theorie Rechnung getragen werden, zum anderen muß auch die in dieser Kontingenz begründete Geschichtlichkeit unseres Universums, d.h. die Emergenz von Komplexität, von einer angemessenen TOE erklärt werden können. Der Autor zeigt, daß ein solcher Anspruch nicht mit den üblichen Komplexitätsmaßen der heutigen Komplexitätstheorien eingelöst werden kann, und schlägt als Alternative einen unmittelbar emergenztheoretisch begründeten Komplexitätsbegriff, den der Topologischen Komplexität vor.

  12. Werner Heisenberg zum 100. Geburtstag: Pionier der Quantenmechanik

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2001-11-01

    Werner Heisenberg war eine der prägendsten Gestalten der Physik des 20. Jahrhunderts. Zu seinen wichtigsten Verdiensten gehören die Grundlegung der Quantenmechanik, die Formulierung der Unschärferelationen sowie die Beteiligung an der Ausarbeitung der Kopenhagener Deutung der Quantenmechanik. Darüber hinaus lieferte er Arbeiten von fundamentalem Charakter zur Theorie des Atomkerns, zur kosmischen Strahlung und zur Quantenfeldtheorie. Während des Krieges war er an den Arbeiten des Uranvereins beteiligt, der die Möglichkeit einer Entwicklung von Kernwaffen untersuchte, jedoch über Vorarbeiten zur Reaktorphysik nicht hinauskam. Wegen dieser Tätigkeit wurde er bei Kriegsende für einige Monate in England interniert. Nach seiner Rückkehr widmete er sich vor allem dem Aufbau der Physik in Deutschland, die während der NS-Zeit nahezu ihrer gesamten Substanz beraubt worden war.

  13. Behavioral Assessment of the Aging Mouse Vestibular System

    PubMed Central

    Tung, Victoria W. K.; Burton, Thomas J.; Dababneh, Edward; Quail, Stephanie L.; Camp, Aaron J.

    2014-01-01

    Age related decline in balance performance is associated with deteriorating muscle strength, motor coordination and vestibular function. While a number of studies show changes in balance phenotype with age in rodents, very few isolate the vestibular contribution to balance under either normal conditions or during senescence. We use two standard behavioral tests to characterize the balance performance of mice at defined age points over the lifespan: the rotarod test and the inclined balance beam test. Importantly though, a custom built rotator is also used to stimulate the vestibular system of mice (without inducing overt signs of motion sickness). These two tests have been used to show that changes in vestibular mediated-balance performance are present over the murine lifespan. Preliminary results show that both the rotarod test and the modified balance beam test can be used to identify changes in balance performance during aging as an alternative to more difficult and invasive techniques such as vestibulo-ocular (VOR) measurements. PMID:25045963

  14. 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.

  15. Non-oxo vanadium(IV) alkoxide chemistry: solid state structures, aggregation equilibria and thermochromic behaviour in solution.

    PubMed

    Westrup, Kátia C M; Gregório, Thaiane; Stinghen, Danilo; Reis, Dayane M; Hitchcock, Peter B; Ribeiro, Ronny R; Barison, Andersson; Back, Davi F; de Sá, Eduardo L; Nunes, Giovana G; Soares, Jaísa F

    2011-04-01

    The reversible thermochromic behaviour of homoleptic [{V(OR)(4)}(n)] complexes in solution [R = Pr(i) (product I), Bu(s) (B(s)), Nep (N) and Cy (C)] is accounted for the existence of an aggregation equilibrium involving dimeric and monomeric species in which vanadium(iv) is respectively five- and four-coordinate. Bulky R groups such as Bu(t) and Pe(t) (tert-pentoxide) prevent aggregation and therefore give rise to exclusively mononuclear compounds (B(t) and P(t), respectively) that are not thermochromic. The complexes and their temperature-dependent interconversion were characterised by single crystal X-ray diffractometry, magnetic susceptibility measurements and electronic, FTIR and EPR spectroscopies in a wide temperature range. Equilibrium constants and enthalpy and entropy changes for the dimerization reactions have been determined and compared with literature data. PMID:21347465

  16. Solarzellen aus Folien-Silizium: Neue Materialien der Photovoltaik

    NASA Astrophysics Data System (ADS)

    Hahn, Giso

    2004-01-01

    Die Photovoltaik wird auf absehbare Zeit vor allem kristallines Silizium als Baumaterial nutzen, mit Tendenz zu billigeren, multikristallinen Wafern. Allerdings werden heutige Wafer aus großen Silizium-Blöcken gesägt, was viel Material verpulvert. Das treibt den Anteil des Wafers an den Gesamtkosten des Solarmoduls auf 50% hoch. Folien-Silizium nutzt dagegen durch eine andere Herstellungstechnik das Material viel besser aus und senkt so die Waferkosten erheblich. Im Wirkungsgrad können Solarzellen aus Folien-Silizium schon fast mit herkömmlichen Zellen konkurrieren. Ein weiterer Vorteil von Folien-Silizium: Es kann relativ problemlos in die Produktionslinien heutiger Solarzellen aus kristallinem Silizium eingegliedert werden. Allerdings sind die attraktivsten Herstellungsverfahren noch nicht serienreif.

  17. Tabulation of hybrid theory calculated e-N2 vibrational and rotational cross sections

    NASA Technical Reports Server (NTRS)

    Chandra, N.; Temkin, A.

    1976-01-01

    Vibrational excitation cross sections of N2 by electron impact are tabulated. Integrated cross sections are given for transitions v yields v prime where o=or v=or 8 in the energy range 0.1 eV=or E=or 10 eV. The energy grid is chosen to be most dense in the resonance region (2 to 4 eV) so that the substructure is present in the numerical results. Coefficients in the angular distribution formula (differential scattering cross section) for transitions v=0 yields v prime = or 8 are also numerically given over the same grid of energies. Simultaneous rotation-vibration coefficients are also given for transitions v=o,j=o; 1 yields v prime=o, j=o,2,4; 1,3,5. All results are obtained from the hybrid theory.

  18. Ejnar Hertzsprung

    NASA Astrophysics Data System (ADS)

    Herrmann, Dieter B.

    Mit diesem Werk von D.B. Herrmann, dem bekannten Astronomiehistoriker und Direktor der Archenhold-Sternwarte und des Zeiss-Großplanetariums in Berlin, liegt zum ersten Mal eine umfassende Biographie des großen Astronomen Ejnar Hertzsprung vor. Ejnar Hertzsprung (1873-1967) verdanken wir die Entdeckung der Riesen- und Zwergsterne, Grundlage für das sog. Hertzsprung-Russel-Diagramm, das eine zentrale Rolle bei der Erforschung der Sternentwicklung spielt. Er bearbeitete erfolgreich Doppelsterne und Veränderliche Sterne und trug Entscheidendes zur modernen Astrophysik bei. Wenig bekannt ist sein Leben, das hier unter Benutzung von Arbeitsmaterial, Interviews mit Zeitgenossen, des Familienarchivs und von Sekundärliteratur von einem kundigen Fachmann beschrieben wird. In D.B. Herrmanns Buch wird nicht nur Persönlichkeit und Werk von Hertzsprung lebendig, sondern auch die astronomische Forschung seiner Zeit. Dieser wertvolle Beitrag zur Wissenschaftsgeschichte wendet sich auch an eine breite allgemeine Leserschaft.

  19. Plasmakristalle an Bord der ISS: Komplexe Plasmen in Schwerelosigkeit

    NASA Astrophysics Data System (ADS)

    Thomas, Hubertus M.; Morfill, Gregor E.

    2005-03-01

    Das deutsch-russische Experiment PKE-Nefedov erforscht komplexe Plasmen in Schwerelosigkeit. Seit 2001 arbeitet es auf der internationalen Raumstation ISS. Komplexe Plasmen bestehen aus einem teilweise ionisierten Gas, das Mikropartikel enthält. Diese Partikel laden sich im Strom der Elektronen und Ionen elektrisch auf. Ihr Verhalten beeinflussen vor allem abgeschirmte Coulomb-Kräfte und Reibungskräfte im Gas. Sie können sich sogar zu einem Plasma-Kristall anordnen. Diese reguläre, dreidimensionale Struktur hat viele Eigenschaften eines echten Kristallgitters. Sie ist jedoch makroskopisch, also klassisch, und die einzelnen Partikel sind viel besser beobachtbar als etwa Atome in kondensierter Materie. Das macht sie zu idealen Modellsystemen für die Erforschung von Kristallen, Phasenübergängen oder von Flüssigkeiten. Komplexe Plasmen zeigen darüber hinaus ganz neue Eigenschaften.

  20. Reduktion der Invasivität bei nadelbasierter Bewegungskompensation für navigierte Eingriffe im Abdomen

    NASA Astrophysics Data System (ADS)

    Maier-Hein, L.; Tekbas, A.; Franz, A. M.; Tetzlaff, R.; Müller, S. A.; Pianka, F.; Wolf, I.; Kauczor, H.-U.; Schmied, B. M.; Meinzer, H.-P.

    Diese Arbeit stellt eine in-vivo Genauigkeitsstudie über das Kombinieren interner und externer Marker für die Bewegungskompensation bei Leberinterventionen vor. Abhängig von der Anzahl und Anordnung der verwendeten Marker sowie der angewandten Echtzeittransformation wurde bei kontinuierlicher Atmung eine Schätzgenauigkeit der Zielposition zwischen 1 und 5 mm erreicht. Das Hinzufügen einer einzigen Hilfsnadel zu einer Menge von Hautmarkern führte zu einer Fehlerreduktion von über 50%. Die Ergebnisse dieser Studie können in der Praxis verwendet werden, um basierend auf dem Tradeoff zwischen geringer Invasivität und hoher Genauigkeit eine geeignete Kombination von internen und externen Markern für eine gegebene Fragestellung zu wählen.

  1. Turbulenzübergang in der Rohrströmung: Die Lösung eines alten Rätsels

    NASA Astrophysics Data System (ADS)

    Eckhardt, Bruno; Hof, Björn; Faisst, Holger

    2006-09-01

    Die Strömung von Flüssigkeiten und Gasen durch eine Röhre kann zwei Zustände annehmen. Einer ist laminar, also gleichmäßig geordnet, einer ist zeitlich-räumlich verwirbelt und turbulent. Mit dem Übergang zur Turbulenz nimmt der Strömungswiderstand drastisch zu. Vor etwa 120 Jahren beschrieb Osborne Reynolds bereits das Verhalten der Rohrströmung sehr genau. Er beobachtete, dass der Turbulenzübergang sehr empfindlich von äußeren Störungen abhängt, was bislang rätselhaft blieb. Dieses Rätsel konnte nun mit einer Kombination aus Computerstudien, Konzepten aus der nichtlinearen Dynamik und speziell entwickelten Experimenten gelöst werden.

  2. Factors Affecting the Outcomes of Carpal Tunnel Surgery: A Review.

    PubMed

    Zyluk-Gadowska, P; Zyluk, A

    2016-08-01

    Ziel der vorliegenden Arbeit war es, unter Berücksichtigung der in Pubmed und Medline veröffentlichten Ergebnisse nach Eingriffen am Karpalkanal zu ermitteln, inwieweit ausgewählte Faktoren wie das Patientenalter, die Dauer der Symptome, die Ausprägung der klinischen und elektrophysiologischen Befunde, das Vorliegen von Begleiterkrankungen und medikolegale Momente die Ergebnisse beeinflussen. Letztlich konnte für keinen der zahlreichen untersuchten Faktoren ein signifikanter Einfluss auf das Langzeitergebnis nachgewiesen werden. Bestehen die Beschwerden länger, sind die klinischen und elektrophysiologischen Befunde ausgeprägter und liegen Begleiterkrankungen vor, so fallen die Ergebnisse weniger gut aus, was darauf hindeutet, dass die betroffenen Patienten etwas weniger von der Operation profitieren. Nur bei Vorliegen von medikolegalen Faktoren wie Rechtsstreit oder Schadenersatzansprüchen lässt sich definitiv ein schlechtes Ergebnis voraussagen. PMID:27580438

  3. Ludwig Boltzmann als Experimentalphysiker: Frühe Bestätigung der Maxwell-Theorie

    NASA Astrophysics Data System (ADS)

    Rumpf, Klemens; Granitzer, Petra

    2006-09-01

    Am Beispiel von Boltzmanns Experimenten zur Bestätigung der Maxwell-Theorie wird dessen hervorragende Begabung auch als Experimentalphysiker deutlich. Die dargestellten Arbeiten fanden etwa 15 Jahre vor den Hertzschen Experimenten statt, zu einem Zeitpunkt also, als die noch junge Maxwell-Theorie dringend experimenteller Bestätigung bedurfte. Boltzmann konnte mit seinen experimentellen Untersuchungen eine direkte Konsequenz der Maxwellschen elektromagnetischen Theorie, die so genannte Maxwell-Relation, bestätigen. Seine Experimente stellten nicht nur lange Zeit den stärksten Beleg für die Richtigkeit der Maxwellschen Lichttheorie dar, sondern waren eine experimentelle Spitzenleistung an der Grenze des damals Möglichen. Besonders Boltzmanns Bestimmung der Dielektrizitätskonstanten von Gasen fand noch Jahrzehnte später Erwähnung in namhaften Lehrbüchern.

  4. [The skull of Combe Capelle].

    PubMed

    Hoffmann, Almut; Wegner, Dietrich

    2002-12-01

    Since the end of World War II two of the most important anthropological artefacts of the Museum für Vor- und Frühgeschichte in Berlin, the skulls and skeletons of Le Moustier and Combe Capelle, were believed to be missing or destroyed, respectively. The postcrania were severely damaged during a fire after the museum was bombed in February 1945, while the skulls were brought to the Soviet Union in 1945. In 1965, the skull of the Neanderthal man from Le Moustier and the chain of the grave of Combe Capelle were found amongst the art objects returned by the Soviet Union into the German Democratic Republic in 1958. However, the Combe Capelle skull was still missing. In the end of 2001 this skull could be found and identified in a store-house of the museum. Now, one the oldest known representatives of Homo sapiens sapiens is again available for scientific research and public exhibitions. PMID:12529957

  5. Demokrit - Planck

    NASA Astrophysics Data System (ADS)

    Rompe, Robert; Treder, Hans-Jürgen

    Es gibt eine Physik, die an die Konstante h gebunden ist und die mit der Atomistik zusammenhängt. Diese h-Physik geht eindeutig auf Planck zurück. Aber, aus dieser Physik folgt die Atomistik als Existenz lokalisierter geladener Teilchen unterschiedlichen Massen nicht, vor allem nicht die des Ladungsquants, so daß also Demokrit mehr behauptet hat, als die Quantenphysik zu beantworten kompetent ist.Translated AbstractDemokrit - PlanckA branch of physics exists closely linked to the constant h and associated with atomism. It is this h-physics that Planck originated. But atomism like existence of localized, charged particles with different masses does not follow from this physics, especially the charge quant. Hence Demokrit asserted more then quantum physics is competent to answer.

  6. Anwendung von Methoden der Logistik und Netzplantechnik zur präzedenz- und ressourcenbeschränkten Ablaufplanung von Echtzeitsystemen

    NASA Astrophysics Data System (ADS)

    Gumzej, Roman; Lipičnik, Martin

    Grundlegende Zusammenhänge zwischen Logistik, Netzplantechnik und Echtzeit sowie den zugehörigen Arten der Ablaufplanung und ihrer Nutzung werden dargestellt. Das Echtzeitprinzip beinhaltet Rechtzeitigkeit von Abläufen, wobei es für eine frühzeitige Beendigung eines Ablaufs keinen Bonus gibt; im Gegensatz zum verspäteten Ablauf, dessen Konsequenzen in der Regel negativ und unabschätzbar sind. Das Just-in-Time-Prinzip gleicht dem der Echtzeit und wird vor allem in der Logistik zur Bezeichnung reibungsloser Abläufe in Beschaffungsketten verwendet. In der Netzplantechnik werden die kritischen Aktivitäten binnen eines Projektes bestimmt, die nicht verzögert werden dürfen, um das Projekt rechtzeitig zu beenden. Außerdem haben die drei Bereiche noch eine Gemeinsamkeit: um realistische Ablaufszenarien darzustellen, müssen in den Analysen auch begrenzte Ressourcen angemessen berücksichtigt werden.

  7. Renaturierung und Management von Heiden

    NASA Astrophysics Data System (ADS)

    Härdtle, Werner; Assmann, Thorsten; van Diggelen, Rudy; von Oheimb, Goddert

    Heiden zählen zu den ältesten und besonders reizvollen Kulturlandschaften Nordwesteuropas. Sie sind bezeichnend für nährstoffarme Böden in wintermilden Gebieten mit hohen Sommerniederschlägen. Während Heiden vor wenigen Jahrhunderten noch weit verbreitet und für manche Landschaften sogar prägend waren, hat sich ihr Areal heute auf wenige, meist in Naturschutzgebieten gelegene Restbestände verkleinert. Zu diesem Rückgang haben maßgeblich Änderungen der Landnutzung, aber auch Nährstoffeinträge aus umgebenden Agrarflächen und atmogene Depositionen beigetragen. In den meisten Ländern der Europäischen Union sind Heiden heute gesetzlich geschützte Ökosysteme, da diese, neben ihrem Erholungswert für den Menschen, Pflanzen- und Tierarten beherbergen, die außerhalb von Heiden nicht oder kaum überlebensfähig sind.

  8. Restaurierung von Seen und Renaturierung von Seeufern

    NASA Astrophysics Data System (ADS)

    Grüneberg, Björn; Ostendorp, Wolfgang; Leßmann, Dieter; Wauer, Gerlinde; Nixdorf, Brigitte

    Süßwasserseen haben als ökosysteme und Lebensraum für Pflanzen und Tiere eine herausragende Bedeutung für die Artenvielfalt auf der Erde und prägen als Landschaftselemente unsere natürliche Umwelt. Seen fungieren als natürliche Stoffsenken, vor allem für Kohlenstoff und Nährstoffe, aber auch als Senken für in ihren Einzugsgebieten emittierte gelöste und feste Schadstoffe. Darüber hinaus ist Wasser eine wichtige Naturressource. Süßwasserseen stellen in den meisten Regionen der Erde lebenswichtige Quellen für die Versorgung mit Trinkwasser und tierischem Eiweiß (Fischfang) dar. Sie dienen als Wasserspeicher für die landwirtschaftliche und industrielle Nutzung. Auch für Erholungsaktivitäten des Menschen kommt ihnen eine große Bedeutung zu.

  9. V/STOLAND digital avionics system for XV-15 tilt rotor

    NASA Technical Reports Server (NTRS)

    Liden, S.

    1980-01-01

    A digital flight control system for the tilt rotor research aircraft provides sophisticated navigation, guidance, control, display and data acquisition capabilities for performing terminal area navigation, guidance and control research. All functions of the XV-15 V/STOLAND system were demonstrated on the NASA-ARC S-19 simulation facility under a comprehensive dynamic acceptance test. The most noteworthy accomplishments of the system are: (1) automatic configuration control of a tilt-rotor aircraft over the total operating range; (2) total hands-off landing to touchdown on various selectable straight-in glide slopes and on a flight path that includes a two-revolution helix; (3) automatic guidance along a programmed three-dimensional reference flight path; (4) navigation data for the automatic guidance computed on board, based on VOR/DME, TACAN, or MLS navid data; and (5) integration of a large set of functions in a single computer, utilizing 16k words of storage for programs and data.

  10. Der Telemanipulator daVinci als mechanisches Trackingsystem

    NASA Astrophysics Data System (ADS)

    Käst, Johannes; Neuhaus, Jochen; Nickel, Felix; Kenngott, Hannes; Engel, Markus; Short, Elaine; Reiter, Michael; Meinzer, Hans-Peter; Maier-Hein, Lena

    Der Telemanipulator daVinci (Intuitive Surgical, Sunnyvale, Kalifornien) ist ein M aster-Slave System für roboterassistierte minimalinvasive Chirurgie. Da er über integrierte Gelenksensoren verfügt, kann er unter Verwendung der daVinci-API als mechanisches Trackingsystem verwendet werden. In dieser Arbeit evaluieren wir die Präzision und Genauigkeit eines daVinci mit Hilfe eines Genauigkeitsphantoms mit bekannten Maßen. Der ermittelte Positionierungsfehler liegt in der Größenordnung von 6 mm und ist somit für einen Großteil der medizinischen Fragestellungen zu hoch. Zur Reduktion des Fehlers schlagen wir daher eine Kalibrierung der Gelenksensoren vor.

  11. Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. III. Responses To translation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.

    1998-01-01

    The three-dimensional (3-D) properties of the translational vestibulo-ocular reflexes (translational VORs) during lateral and fore-aft oscillations in complete darkness were studied in rhesus monkeys at frequencies between 0.16 and 25 Hz. In addition, constant velocity off-vertical axis rotations extended the frequency range to 0.02 Hz. During lateral motion, horizontal responses were in phase with linear velocity in the frequency range of 2-10 Hz. At both lower and higher frequencies, phase lags were introduced. Torsional response phase changed more than 180 degrees in the tested frequency range such that torsional eye movements, which could be regarded as compensatory to "an apparent roll tilt" at the lowest frequencies, became anticompensatory at all frequencies above approximately 1 Hz. These results suggest two functionally different frequency bandwidths for the translational VORs. In the low-frequency spectrum (<<0.5 Hz), horizontal responses compensatory to translation are small and high-pass-filtered whereas torsional response sensitivity is relatively frequency independent. At higher frequencies however, both horizontal and torsional response sensitivity and phase exhibit a similar frequency dependence, suggesting a common role during head translation. During up-down motion, vertical responses were in phase with translational velocity at 3-5 Hz but phase leads progressively increased for lower frequencies (>90 degrees at frequencies <0.2 Hz). No consistent dependence on static head orientation was observed for the vertical response components during up-down motion and the horizontal and torsional response components during lateral translation. The frequency response characteristics of the translational VORs were fitted by "periphery/brain stem" functions that related the linear acceleration input, transduced by primary otolith afferents, to the velocity signals providing the input to the velocity-to-position neural integrator and the oculomotor plant. The

  12. Die Amtliche Sammlung von Untersuchungsverfahren nach § 64 LFGB, § 35 Vorläufiges Tabakgesetz und § 28b Gentechnikgesetz - ein Instrument der amtlichen Lebensmittelüberwachung

    NASA Astrophysics Data System (ADS)

    Renger, Silke; Stachel, Carolin

    Immer wieder werden Skandale in Zusammenhang mit Lebensmitteln bekannt. Schlagworte wie BSE, Gammelfleisch, Acrylamid, Cumarin oder auch Melamin, Dioxin sind den Verbrauchern geläufig und erschüttern das Vertrauen in ein gesundes und ernährungsphysiologisch wertvolles Lebensmittel. Das Bewusstsein des Verbrauchers hinsichtlich der Ernährung und der Auswahl beim Kauf der Lebensmittel hat sich in den vergangenen Jahren deutlich verändert. Bei der Auswahl seiner Lebensmittel liegt sein Augenmerk verstärkt auf gesunden, qualitativ hochwertigen und vor allem sicheren Lebensmitteln. Dies wurde insbesondere bei dem verhaltenen Kauf von Fleisch und Fleischerzeugnissen während der BSE-Krise oder auch dem kürzlich aufgetretenen Gammelfleischskandal deutlich.

  13. Modulare LDAP-Server-, -Protokoll und - Funktionserweiterungen am Beispiel von OpenLDAP

    NASA Astrophysics Data System (ADS)

    Pluta, Daniel

    In diesem Artikel wird ein Standardisierungsvorschlag für eine LDAP-Protokollerweiterung und deren Referenzimplementierung in Form einer modularen Erweiterung für die LDAP-Software-Suite des OpenLDAPProjektes vorgestellt. Nach einer Einführung in und einem Überblick über die wichtigsten OpenLDAP-Komponenten stellen wir unseren Lösungsansatz vor und gehen auf seine technischen Details ein. Ziel dieses Overlays ist die Implementierung einer neuen Funktionalität, die vom LDAP-Protokoll bisher nicht vorgesehen ist: Der Umfang der Suchergebnismenge soll serverseitig, dezentral und in der Granularität ganzer Objekte in Abhängigkeit von der aktuellen Serverzeit (konfigurierbar) eingeschränkt werden.

  14. Herausforderungen und Best Practices bei der Speicherung von multi-valued Attributen in LDAP-basierten Verzeichnisdiensten

    NASA Astrophysics Data System (ADS)

    Hommel, Wolfgang; Pluta, Daniel

    LDAP-basierte Verzeichnisdienste unterscheiden sich von relationalen Datenbankmanagementsystemen unter anderem stark bezüglich der Datenmodellierung. Dieser Artikel vertieft eingangs die Herausforderungen bei der LDAP-spezifischen Abbildung von Relationen zwischen mehreren multivalued Attributen. Die Diskussion erfolgt vor dem Hintergrund, dass einerseits Verzeichnisdienste generell nur bedingt zur Speicherung von Relationen geeignet sind und dass andererseits multi-valued Attribute ein mächtiges LDAP-Instrument sind, zu dem es in relationalen Datenbanksystemen keine direkte Entsprechung gibt. Anschließend werden Lösungskonzepte vorgestellt und mögliche Weiterentwicklungen des IntegraTUM-LDAP-Schemas zu deren Umsetzung skizziert, eine exemplarische Implementierung präsentiert und die Ergebnisse der bisherigen Entwicklung des IntegraTUM-Schemas gegenübergestellt.

  15. Biochips und ihr Einsatz in der Lebensmittelanalytik

    NASA Astrophysics Data System (ADS)

    Huber, Ingrid; Zeltz, Patric

    Mit der Verbreitung des Begriffes "Biochip“ in den biotechnologischen Medien wurde Ende der 1990er-Jahre zunächst der Eindruck erweckt, dass die Computerelektronik in die molekularbiologischen Anwendungen eingestiegen ist [18]. In nur wenigen Jahren hat sich die Biochiptechnologie zu einem Verfahren entwickelt, das aus der molekularbiologischen Grundlagenforschung nicht mehr wegzudenken ist und über eine Vielzahl von Einsatzbereichen verfügt. Die Biochiptechnologie ermöglicht die Miniaturisierung von DNA-, RNA- bzw. Proteinanalytik in hochparallelen Formaten. Dieser hohe Parallelisierungsgrad ist einer der wesentlichen Vorteile dieser Technik gegenüber klassischen molekularbiologischen Methoden. Sie wird heutzutage vor allem in der Genomforschung eingesetzt, für Genexpressionsstudien, zum Screening von single nucleotide polymorphisms (SNPs), in der pharmakogenetischen Forschung sowie in der Erforschung von Erbkrankheiten und in der Krebsforschung [1, 7, 19]. Neben vielen weiteren Bereichen finden Biochips auch spezielle Anwendungen in der Lebensmittelanalytik.

  16. Kosteneffiziente Honbearbeitung durch intelligente und flexible Verknüpfung von autarken Honzentren

    NASA Astrophysics Data System (ADS)

    Roth, Günther

    Die Planungsabteilungen in der Automobilindustrie werden vor immer größere Herausforderungen gestsellt. Der zur Verfügung stehende Zeitraum zu einer seriensicheren Umsetzung der entwicklungs- und produktionstechnischen Forderungen wird von Projekt zu Projekt kürzer. Aufgrund des hohen Wettbewerbsdrucks und daraus resultierenden erforderlichen Kostenoptimierungen, die schnelleren Timeto-market-und Innovationszyklen und die vermeintlich zur Kundenbindung erforderlichen, kaum mehr überschaubaren Diversifizierungen in den Modellpaletten lassen den Planungshorizont immer kürzer werden. Die zu beschaffenden Fertigungsanlagen sollen aber in den nächsten 8-12 Jahren all die Varianten produzieren können, die heute nur teilweise oder noch gar nicht bekannt sind.

  17. Hochproduktive Werkzeugbeschichtungen

    NASA Astrophysics Data System (ADS)

    Kruszynski, Jacek

    Trotz vielfältiger Bemühungen, die Near Net Shape Technologie in weiten Produktionsbereichen zu etablieren, ist die spanabhebende Bearbeitung nach wie vor ein wesentlicher Faktor im Produktionsprozess und kann als solcher die Produktivität entscheidend beeinflussen. Allerdings haben sich die Anforderungen an den Zerspanungsprozess im Laufe der letzten Jahre stark gewandelt. Die Reduktion von Taktzeiten und die Erhöhung der Schnittgeschwindigkeiten bedeuten eine verstärkte mechanische und thermische Belastung für die Schneidstoffe. Hinzu kommt die Forderung nach Einengung der Toleranzen und Einsparung von Arbeitsgängen. Diese neuen Rahmenbedingungen führen dazu, dass eine stetige Anpassung der Werkzeuge sowohl hinsichtlich der Schneidengeometrie als auch im Bereich der Schneidstoffe selbst notwendig ist.

  18. Osteognathostomata

    NASA Astrophysics Data System (ADS)

    Schultze, Hans-Peter

    Noch häufig, vor allem im englischen Sprachraum, wird für die fischartigen Wirbeltiere mit Knochenskelett, also die Actinopterygii und Sarcopterygii, der Begriff "Osteichthyes" (Knochenfische) verwendet. Da sich jedoch aus einem Subtaxon der Sarcopterygier die Tet rapoda entwickelten (S. 322), würde diese Gruppierung ein paraphyletisches Taxon darstellen. Hier wird daher dem Vorschlag W. Hennigs (1983) gefolgt und die Schwestergruppe der Chondrichthyes Osteognathostomata genannt: Sie enthält alle weiteren kiefertragenden Wirbeltiere mit Knochenskelett (Name!) (Abb. 201). Die Sarcopterygii umfassen demnach verschiedene fossile Gruppen, die rezenten Reliktgruppen der Dipnoi (Lungenfische) und Actinistia (Hohlstachler) sowie die Tetrapoda und ihre Stammgruppenvertreter. (Neuerdings wird in der Literatur aus denselben Gründen einer konsequent phylogenetischen Systematisierung wieder die Gruppierung Osteichthyes, aber unter Einschluss der Tetrapoda, verwendet!).

  19. Wie alles begann

    NASA Astrophysics Data System (ADS)

    Steger, Almut

    An deutschen Universitäten entstand die Statistik als selbständige Wissenschaft vor gut 250 Jahren. Sie war zunächst reine Staatenbeschreibung. Erst im 19. Jahrhundert bildete sich der heutige Begriff von Statistik heraus. In mehreren Ländern gründete man damals statistische Vereine und länderübergreifend das Internationale Statistische Institut (ISI). Die deutschen Statistiker waren zwar ebenfalls national und international sehr aktiv, doch zur Gründung der Deutschen Statistischen Gesellschaft kam es erst 1911. Das Kapitel beschreibt diese Entwicklung, besonders ausführlich den Gründungsprozess. Danach wird über die schon mit der Gründung beginnenden, äußerst regen und zum Teil kontrovers ausgetragenen wissenschaftlichen Diskussionen berichtet, die jedoch mit dem Kriegsausbruch 1914 weitgehend zum Erliegen kamen.

  20. Three-dimensional organization of vestibular related eye movements to rotational motion in pigeons

    NASA Technical Reports Server (NTRS)

    Dickman, J. D.; Beyer, M.; Hess, B. J.

    2000-01-01

    During rotational motions, compensatory eye movement adjustments must continually occur in order to maintain objects of visual interest as stable images on the retina. In the present study, the three-dimensional organization of the vestibulo-ocular reflex in pigeons was quantitatively examined. Rotations about different head axes produced horizontal, vertical, and torsional eye movements, whose component magnitude was dependent upon the cosine of the stimulus axis relative to the animal's visual axis. Thus, the three-dimensional organization of the VOR in pigeons appears to be compensatory for any direction of head rotation. Frequency responses of the horizontal, vertical, and torsional slow phase components exhibited high pass filter properties with dominant time constants of approximately 3 s.

  1. Molecular identification and susceptibility of clinically relevant Scedosporium spp. in China.

    PubMed

    Wang, Hong; Wan, Zhe; Li, Ruoyu; Lu, Qiaoyun; Yu, Jin

    2015-01-01

    As various new sibling species within the Scedosporium spp. have been described recently, this study was conducted to investigate distribution and antifungal susceptibility profiles of the different species of Scedosporium spp. in China. Twenty-one clinical strains of Scedosporium from China and two strains from Japan were reidentified by MLSA. The analysis included BT2, CAL, RPB, SOD, and ACT and the combination of the five loci. Pseudallescheria boydii complex (17 strains) and S. apiospermum (6 strains) were identified. P. boydii complex included four closely related subgroups: P. boydii (9 strains), P. ellipsoidea (6 strains), P. fusoidea (1 strain), and P. angusta (1 strain). There were no significant differences in MICs for neither VOR, POS, nor AMB over all the five species in study. For itraconazole, intraspecific diversity was evident. PMID:26550562

  2. IQM-Reifegradmodell für die Bewertung und Verbesserung des Information Lifecycle Management Prozesses

    NASA Astrophysics Data System (ADS)

    Baškarada, Saša; Gebauer, Marcus; Koronios, Andy; Gao, Jing

    Heutige Organisationen produzieren und speichern mehr Informationen als je zuvor. Der resultierende Informationsüberfluss, zusammen mit einem Mangel an Qualitätssicherung für das Information Lifecycle Management, führt zu einem unsicheren Status der Informationsqualität in vielen Organisationen. Weiterhin hat sich herausgestellt, dass das Bewerten, Verbessern und Steuern der Informationsqualität ein offenkundig schwieriges Unterfangen ist. Dieses Kapitel stellt ein Modell zur Bewertung und Verbesserung der Information Quality Management Capability Maturity (IQM-Reifegrad) vor. Es wird ein Satz von Kriterien vorgestellt, der aus Literaturrecherche und Fallstudien abgeleitet wurde. Die Reifegradindikatoren werden validiert und in einem mehrstufigen Reifegradmodell durch eine Delphi-Studie gruppiert. Das abgeleitete IQM-Reifegradmodell hilft Organisationen ihre bestehenden Praktiken im IQM zu bewerten und potentielle Lücken und Verbesserungsstrategien zu ermitteln.

  3. 757 Path Loss Measurements

    NASA Technical Reports Server (NTRS)

    Horton, Kent; Huffman, Mitch; Eppic, Brian; White, Harrison

    2005-01-01

    Path Loss Measurements were obtained on three (3) GPS equipped 757 aircraft. Systems measured were Marker Beacon, LOC, VOR, VHF (3), Glide Slope, ATC (2), DME (2), TCAS, and GPS. This data will provide the basis for assessing the EMI (Electromagnetic Interference) safety margins of comm/nav (communication and navigation) systems to portable electronic device emissions. These Portable Electronic Devices (PEDs) include all devices operated in or around the aircraft by crews, passengers, servicing personnel, as well as the general public in the airport terminals. EMI assessment capability is an important step in determining if one system-wide PED EMI policy is appropriate. This data may also be used comparatively with theoretical analysis and computer modeling data sponsored by NASA Langley Research Center and others.

  4. elecTUM: Umsetzung der eLearning-Strategie der Technischen Universität München

    NASA Astrophysics Data System (ADS)

    Rathmayer, Sabine; Gergintchev, Ivan

    An der TUM wurde ein umfassendes und integriertes eLearning-Konzept umgesetzt, welches Präsenzstudium und eLearning in allen Leistungsbereichen der Universität miteinander verzahnt. Ein besonderer Schwerpunkt lag dabei in der Schaffung einer effizienten und wettbewerbsfähigen integrierten eLearning Infrastruktur in Hinblick auf die noch weiter steigenden Studienanfängerzahlen ab dem Jahr 2011 sowie die Umsetzung von eBologna. Die Etablierung einer hochschulweiten Lernplattform stellte eine wesentliche Basis für die Umsetzung der eLearning-Strategie dar. Die wissenschaftliche und wirtschaftliche Anschlussfähigkeit im Hinblick auf eine Verwertung der Projektergebnisse wurde durch die aktive Beteiligung an einer Vielzahl hochschulübergreifender Arbeitskreise, Fachtagungen und Kooperationen, vor allem über Organisations- und Dienstleistungsmodelle sowie innovative technische Entwicklungen, sichergestellt.

  5. Qualität auf dem Prüfstand

    NASA Astrophysics Data System (ADS)

    Michaelis, Michael

    An einem Wochenende im Dezember 2009 beendete der chinesische Eisenbahn-Vizeminister Hu Yadong in Begleitung einer hochrangigen Delegation aus Experten des Department of Safety seines Ministeriums eine mehrtägige Europareise mit einem Besuch in der Konzernzentrale des weltweit führenden Herstellers von Bremssystemen für Schienen- und Nutzfahrzeuge in München. Schon in wenigen Jahren wird China über die weltweit größte Flotte an Hochgeschwindigkeitszügen verfügen und dabei sind Sicherheit und Qualität vorrangige Anforderungen. Knorr-Bremse liefert 100% der Bremsanlagen dieser Züge und hat vor kurzem mit rund 500 Millionen Euro den größten Auftrag in der Firmengeschichte erhalten. Das Unternehmen wird zusammen mit seinen chinesischen Partnern insgesamt 2.720 neue Wagen des chinesischen Hochgeschwindigkeitszuges CRH3 mit Brems- und Türsystemen ausrüsten.

  6. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. IV. Responses after spectacle-induced adaptation

    NASA Technical Reports Server (NTRS)

    Clendaniel, R. A.; Lasker, D. M.; Minor, L. B.; Shelhamer, M. J. (Principal Investigator)

    2001-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by sinusoidal rotations from 0.5 to 15 Hz and acceleration steps up to 3,000 degrees /s(2) to 150 degrees /s was studied in six squirrel monkeys following adaptation with x2.2 magnifying and x0.45 minimizing spectacles. For sinusoidal rotations with peak velocities of 20 degrees /s, there were significant changes in gain at all frequencies; however, the greatest gain changes occurred at the lower frequencies. The frequency- and velocity-dependent gain enhancement seen in normal monkeys was accentuated following adaptation to magnifying spectacles and diminished with adaptation to minimizing spectacles. A differential increase in gain for the steps of acceleration was noted after adaptation to the magnifying spectacles. The gain during the acceleration portion, G(A), of a step of acceleration (3,000 degrees /s(2) to 150 degrees /s) increased from preadaptation values of 1.05 +/- 0.08 to 1.96 +/- 0.16, while the gain during the velocity plateau, G(V), only increased from 0.93 +/- 0.04 to 1.36 +/- 0.08. Polynomial fits to the trajectory of the response during the acceleration step revealed a greater increase in the cubic than the linear term following adaptation with the magnifying lenses. Following adaptation to the minimizing lenses, the value of G(A) decreased to 0.61 +/- 0.08, and the value of G(V) decreased to 0.59 +/- 0.09 for the 3,000 degrees /s(2) steps of acceleration. Polynomial fits to the trajectory of the response during the acceleration step revealed that there was a significantly greater reduction in the cubic term than in the linear term following adaptation with the minimizing lenses. These findings indicate that there is greater modification of the nonlinear as compared with the linear component of the VOR with spectacle-induced adaptation. In addition, the latency to the onset of the adapted response varied with the dynamics of the stimulus. The findings were modeled with a bilateral model

  7. Niob

    NASA Astrophysics Data System (ADS)

    Dettner, H. W.; Franssen, H.; Giesen, K.; Hayes, E. T.; Holetzko, H.; Keysselitz, B.; Loebich, O.; Pelzel, E.; Reinsch, W.; Rostoker, W.; Saur, G.; Volk, K. E.; Wallbaum, H. J.; Borchers, Heinz; Schmidt, Ernst

    Niob — im angelsächsischen Schrifttum vielfach auch als "Columbium" (chemisches Zeichen "Cb") bezeichnet — wurde bis vor wenigen Jahren vorwiegend als Legierungselement in den sog. "Superalloys" oder zur Stabilisierung austenitischer Stähle verwendet. In neuerer Zeit wurden zahlreiche hochwarmfeste Legierungen auf Niobbasis für den Triebwerksbau und korrosionsbeständige Legierungen u. a. für die Verwendung als Hüllenwerkstoff im Reaktorbau entwickelt [D 2, G 1, H 2]. Niob-Uran-Legierungen scheinen sich zur Herstellung von Brennstoffelementen in Reaktoren zu bewähren. Vereinzelt wird Niob auch an Stelle des Tantals für hochwertige Senderöhren, Röntgenröhren und Hochspannungsgleichrichter verwendet. In der Vakuumtechnik dient es als wirksames "bulk getter" (nicht verdampfendes Getter) für den Temperaturbereich zwischen 400 und 900 °C [E 5].

  8. Verbesserung der Prozessbedingungen beim Einlippentiefbohren durch unterschiedliche Formen der Vorschubmodulation

    NASA Astrophysics Data System (ADS)

    Eisseler, Rocco

    Das Tiefbohren mit Einlippenwerkzeugen ist bei vielen Anwendungen das Verfahren der ersten Wahl, vor allem wenn kleine und kleinste Bohrungsdurchmesser, ein sehr großes Verhältnis zwischen Bohrtiefe und Durchmesser (l/D) und eine hohe Bearbeitungsqualität gefordert werden. Der erreichbare Durchmesserbereich des Verfahrens liegt zwischen D = 0,5 mm und 40 mm, wobei die möglichen Bohrtiefen von l = 3 x D bis 250 x D reichen. Diese Werte beziehen sich auf das Vollbohren, beim Aufbohren können noch größere Durchmesser erreicht werden [1]. Die erreichbare Oberflächenqualität ist so hoch, dass in den meisten Fällen auf eine nachfolgende Feinbearbeitung verzichtet werden kann.

  9. [Milestones in Gynecological Oncology over the Last 20 Years

    PubMed

    Pfleiderer, A.

    2000-12-01

    In den letzten Jahrzehnten vollzog sich auch auf dem Gebiet der gynäkologischen Onkologie ein grundlegender Wandel - dafür stehen Meilensteine. In der Natur der klinischen Medizin liegt jedoch, dass die für die Entwicklung, Diagnostik und Therapie relevanten erst dann, wenn sie sich bewährt und als dauerhaft erwiesen haben, als solche zu erkennen sind. Deshalb darf es nicht verwundern, dass sie auf dem Gebiet der gynäkologischen Onkologie meist schon vor über 20 Jahren gesetzt wurden. Obwohl es heute scheint, als seien zur Diagnose und Therapie gynäkologischer Karzinome keine grundlegend neuen Gesichtspunkte und Techniken hinzugekommen, gab es in dieser Zeit gravierende Veränderungen. Copyright 2000 S. Karger GmbH, Freiburg PMID:11441271

  10. Another Look at the Great Area-Coverage Controversy of the 1950's

    NASA Astrophysics Data System (ADS)

    Blanchard, Walter

    2005-09-01

    In the immediate aftermath of WW2 there sprang up an international argument over the relative merits for aerial navigation of area-coverage radio navaids versus point-source systems. The United States was in favour of point-source whereas the UK proposed area-coverage, systems for which had successfully been demonstrated under very adverse conditions during the war. It rumbled on for many years, not being finally settled until the ICAO Montreal Conference of 1959 decided for point-source. Since then, VOR/DME/ADF/ILS have been the standard aviation radio navaids and there seems little likelihood of any change in the near future, GNSS notwithstanding, if one discounts the phasing-out of ADF. It now seems sufficiently in the past to perhaps allow a dispassionate evaluation of the technical arguments used at the time the political ones can be left to another place and time.

  11. Evaluation of several navigation algorithms for application to general aviation

    NASA Technical Reports Server (NTRS)

    Conrad, B.; Korsak, A. J.; Jackson, C. T., Jr.

    1975-01-01

    Using data obtained in flight, three position determining algorithms for use by general aviation aircraft were evaluated representing increasing software requirements. These were a DME only, DME/air data and blended DME/air data. Although each step represented additional software with resultant increase in position accuracy, all could be performed on a programmable electronic desk calculator. Results from the computation of aircraft position using the three algorithms are presented. The algorithms employed can be extended to accept VOR, TACAN bearing, ADF, or other NAVAID Data. To obtain the flight data an experimental system was configured and flown on a general aviation aircraft. Principal hardware elements (all with low-cost potential) were a programmable calculator, a single DME receiver (multiplexed for multiple DME use) and a low-cost air speed sensor (shed-vortex principle). The flight test demonstrated satisfactory performance of these principal elements.

  12. Molecular Identification and Susceptibility of Clinically Relevant Scedosporium spp. in China

    PubMed Central

    Wang, Hong; Wan, Zhe; Li, Ruoyu; Lu, Qiaoyun; Yu, Jin

    2015-01-01

    As various new sibling species within the Scedosporium spp. have been described recently, this study was conducted to investigate distribution and antifungal susceptibility profiles of the different species of Scedosporium spp. in China. Twenty-one clinical strains of Scedosporium from China and two strains from Japan were reidentified by MLSA. The analysis included BT2, CAL, RPB, SOD, and ACT and the combination of the five loci. Pseudallescheria boydii complex (17 strains) and S. apiospermum (6 strains) were identified. P. boydii complex included four closely related subgroups: P. boydii (9 strains), P. ellipsoidea (6 strains), P. fusoidea (1 strain), and P. angusta (1 strain). There were no significant differences in MICs for neither VOR, POS, nor AMB over all the five species in study. For itraconazole, intraspecific diversity was evident. PMID:26550562

  13. Die Struktur von schlankem Materialfluss mit Lean Production Kanban und Innovationen

    NASA Astrophysics Data System (ADS)

    Scheid, Wolf-Michael

    In der Literatur wird Materialfluss überwiegend in Spezialdisziplinen betrachtet, etwa der Steuerungslogik, der Logistiktechnik oder dem Supply Chain Management. Ein charakterisierendes Merkmal des Materialflusses ist jedoch, dass er sich aus vielfältigen Einzelbausteinen zusammensetzt, die alle harmonisch abgestimmt sein müssen. Die maximal erreichbare Effizienz wird nicht durch Höchstleistungen in dem einen oder anderen Spezialthema bestimmt, sondern durch das schwächste Glied im gesamten komplexen Netzwerk. Den Schnittstellen zwischen den betroffenen Fachbereichen in einem Unternehmen kommt hier eine ganz besondere Bedeutung zu: Erst ein harmonischer Einklang ermöglicht hohe Effektivität. Dies setzt umfassendes Verständnis für interdisziplinäre Notwendigkeiten, ein hohes Maß an Abstimmung mit den operativen Prozessen und letztlich einen einvernehmlichen Umgang und den Respekt vor den Problemstellungen des Anderen voraus.

  14. Efficient transfer of weather information to the pilot in flight

    NASA Technical Reports Server (NTRS)

    Mcfarland, R. H.

    1982-01-01

    Efficient methods for providing weather information to the pilot in flight are summarized. Use of discrete communications channels in the aeronautical, VHF band or subcarriers in the VOR navigation band are considered the best possibilities. Data rates can be provided such that inputs to the ground based transmitters from 2400 band telephone lines are easily accommodated together with additional data. The crucial weather data considered for uplinking are identified as radar reflectivity patterns relating to precipitation, spherics data, hourly sequences, nowcasts, forecasts, cloud top heights with freezing and icing conditions, the critical weather map and satellite maps. NEXRAD, the ground based, Doppler weather radar which will produce an improved weather product also encourages use of an uplink to fully utilize its capability to improve air safety.

  15. The effect of space flight on spatial orientation

    NASA Technical Reports Server (NTRS)

    Reschke, Millard F.; Bloomberg, Jacob J.; Harm, Deborah L.; Paloski, William H.; Satake, Hirotaka

    1992-01-01

    Both during and following early space missions, little neurosensory change in the astronauts was noted as a result of their exposure to microgravity. It is believed that this lack of in-flight adaptation in the spatial orientation and perceptual-motor system resulted from short exposure times and limited interaction with the new environment. Parker and Parker (1990) have suggested that while spatial orientation and motion information can be detected by a passive observer, adaptation to stimulus rearrangement is greatly enhanced when the observer moves through or acts on the environment. Experience with the actual consequences of action can be compared with those consequences expected on the basis of prior experience. Space flight today is of longer duration, and space craft volume has increased. These changes have forced the astronauts to interact with the new environment of microgravity, and as a result substantial changes occur in the perceptual and sensory-motor repsonses reflecting adaptation to the stimulus rearrangement of space flight. We are currently evaluating spatial orientation and the perceptual-motor systems' adaptation to microgravity by examining responses of postural control, head and gaze stability during locomotion, goal oriented vestibulo-ocular reflex (VOR), and structured quantitative perceptual reports. Evidence suggests that humans can successfully replace the gravitational reference available on Earth with cues available within the spacecraft or within themselves, but that adaptation to microgravity is not appropriate for a return to Earth. Countermeasures for optimal performance on-orbit and a successful return to earth will require development of preflight and in-flight training to help the astronauts acquire and maintain a dual adaptive state. An understanding of spatial orientation and motion perception, postural control, locomotion, and the VOR will aid in this process.

  16. In vitro antifungal susceptibility testing of Scopulariopsis brevicaulis strains using agar diffusion method.

    PubMed

    Skóra, Magdalena; Macura, Anna B

    2011-01-01

    The genus Scopulariopsis is a common soil saprotroph and has been isolated from air, organic waste and also from plant, animal and human tissues. Scopulariopsis has mainly been associated in humans with superficial mycoses, but it has also been described as the cause of subcutaneous and invasive infections. The most common aetiological agent of infections in humans is Scopulariopsis brevicaulis. This species has been reported to be resistant in vitro to broad-spectrum antifungal agents available today. The aim of the study was to establish in vitro antifungal susceptibility of 35 S. brevicaulis strains against amphotericin B (AMB), flucytosine (FC), caspofungin (CAS), terbinafine (TER), ciclopirox (CIC), voriconazole (VOR), clotrimazole (CTR), miconazole (MCZ), econazole (ECO), ketoconazole (KET), itraconazole (ITR), and fluconazole (FLU). Antifungal susceptibility tests were evaluated by an agar diffusion method (Neo-Sensitabs, Rosco, Denmark). AMB, FC, CAS, ITR and FLU showed no antifungal activity against S. brevicaulis. TER, CIC, CTR, KET, VOR, ECO, and MCZ revealed inhibitory activity for S. brevicaulis, but it varied for each of the drugs. The best antifungal effect was observed for TER and CIC. All isolates had large inhibition zones for TER and CIC. CTR was also inhibitory for all tested S. brevicaulis isolates, but the diameters of inhibition zones were smaller than for TER and CIC. Nearly 89% isolates showed inhibition zones for KET and the mean diameter of the inhibition zone was comparable to CTR. The least antifungal activity exhibited VQR, ECO and MCZ. Because of the multiresistance of S. brevicaulis, infections due to this species may not respond to particular antifungal treatment and other therapeutic approaches should be considered, e.g., combined therapy and/or surgery. PMID:21682097

  17. Flocculus Purkinje cell signals in mouse Cacna1a calcium channel mutants of escalating severity: an investigation of the role of firing irregularity in ataxia.

    PubMed

    Stahl, John S; Thumser, Zachary C

    2014-11-15

    Mutation of the Cacna1a gene for the P/Q (CaV2.1) calcium channel invariably leads to cerebellar dysfunction. The dysfunction has been attributed to disrupted rhythmicity of cerebellar Purkinje cells, but the hypothesis remains unproven. If irregular firing rates cause cerebellar dysfunction, then the irregularity and behavioral deficits should covary in a series of mutant strains of escalating severity. We compared firing irregularity in floccular and anterior vermis Purkinje cells in the mildly affected rocker and moderately affected tottering Cacna1a mutants and normal C57BL/6 mice. We also measured the amplitude and timing of modulations of floccular Purkinje cell firing rate during the horizontal vestibuloocular reflex (VOR, 0.25-1 Hz) and the horizontal and vertical optokinetic reflex (OKR, 0.125-1 Hz). We recorded Purkinje cells selective for rotational stimulation about the vertical axis (VAPCs) and a horizontal axis (HAPCs). Irregularity scaled with behavioral deficit severity in the flocculus but failed to do so in the vermis, challenging the irregularity hypothesis. Mutant VAPCs exhibited unusually strong modulation during VOR and OKR, the response augmentation scaling with phenotypic severity. HAPCs exhibited increased OKR modulation but in tottering only. The data contradict prior claims that modulation amplitude is unaffected in tottering but support the idea that attenuated compensatory eye movements in Cacna1a mutants arise from defective transfer of Purkinje cell signals to downstream circuitry, rather than attenuated synaptic transmission within the cerebellar cortex. Shifts in the relative sizes of the VAPC and HAPC populations raise the possibility that Cacna1a mutations influence the development of floccular zone architecture. PMID:25143538

  18. Flocculus Purkinje cell signals in mouse Cacna1a calcium channel mutants of escalating severity: an investigation of the role of firing irregularity in ataxia

    PubMed Central

    Thumser, Zachary C.

    2014-01-01

    Mutation of the Cacna1a gene for the P/Q (CaV2.1) calcium channel invariably leads to cerebellar dysfunction. The dysfunction has been attributed to disrupted rhythmicity of cerebellar Purkinje cells, but the hypothesis remains unproven. If irregular firing rates cause cerebellar dysfunction, then the irregularity and behavioral deficits should covary in a series of mutant strains of escalating severity. We compared firing irregularity in floccular and anterior vermis Purkinje cells in the mildly affected rocker and moderately affected tottering Cacna1a mutants and normal C57BL/6 mice. We also measured the amplitude and timing of modulations of floccular Purkinje cell firing rate during the horizontal vestibuloocular reflex (VOR, 0.25–1 Hz) and the horizontal and vertical optokinetic reflex (OKR, 0.125–1 Hz). We recorded Purkinje cells selective for rotational stimulation about the vertical axis (VAPCs) and a horizontal axis (HAPCs). Irregularity scaled with behavioral deficit severity in the flocculus but failed to do so in the vermis, challenging the irregularity hypothesis. Mutant VAPCs exhibited unusually strong modulation during VOR and OKR, the response augmentation scaling with phenotypic severity. HAPCs exhibited increased OKR modulation but in tottering only. The data contradict prior claims that modulation amplitude is unaffected in tottering but support the idea that attenuated compensatory eye movements in Cacna1a mutants arise from defective transfer of Purkinje cell signals to downstream circuitry, rather than attenuated synaptic transmission within the cerebellar cortex. Shifts in the relative sizes of the VAPC and HAPC populations raise the possibility that Cacna1a mutations influence the development of floccular zone architecture. PMID:25143538

  19. A kinematic model for 3-D head-free gaze-shifts

    PubMed Central

    Daemi, Mehdi; Crawford, J. Douglas

    2015-01-01

    Rotations of the line of sight are mainly implemented by coordinated motion of the eyes and head. Here, we propose a model for the kinematics of three-dimensional (3-D) head-unrestrained gaze-shifts. The model was designed to account for major principles in the known behavior, such as gaze accuracy, spatiotemporal coordination of saccades with vestibulo-ocular reflex (VOR), relative eye and head contributions, the non-commutativity of rotations, and Listing's and Fick constraints for the eyes and head, respectively. The internal design of the model was inspired by known and hypothesized elements of gaze control physiology. Inputs included retinocentric location of the visual target and internal representations of initial 3-D eye and head orientation, whereas outputs were 3-D displacements of eye relative to the head and head relative to shoulder. Internal transformations decomposed the 2-D gaze command into 3-D eye and head commands with the use of three coordinated circuits: (1) a saccade generator, (2) a head rotation generator, (3) a VOR predictor. Simulations illustrate that the model can implement: (1) the correct 3-D reference frame transformations to generate accurate gaze shifts (despite variability in other parameters), (2) the experimentally verified constraints on static eye and head orientations during fixation, and (3) the experimentally observed 3-D trajectories of eye and head motion during gaze-shifts. We then use this model to simulate how 2-D eye-head coordination strategies interact with 3-D constraints to influence 3-D orientations of the eye-in-space, and the implications of this for spatial vision. PMID:26113816

  20. A kinematic model for 3-D head-free gaze-shifts.

    PubMed

    Daemi, Mehdi; Crawford, J Douglas

    2015-01-01

    Rotations of the line of sight are mainly implemented by coordinated motion of the eyes and head. Here, we propose a model for the kinematics of three-dimensional (3-D) head-unrestrained gaze-shifts. The model was designed to account for major principles in the known behavior, such as gaze accuracy, spatiotemporal coordination of saccades with vestibulo-ocular reflex (VOR), relative eye and head contributions, the non-commutativity of rotations, and Listing's and Fick constraints for the eyes and head, respectively. The internal design of the model was inspired by known and hypothesized elements of gaze control physiology. Inputs included retinocentric location of the visual target and internal representations of initial 3-D eye and head orientation, whereas outputs were 3-D displacements of eye relative to the head and head relative to shoulder. Internal transformations decomposed the 2-D gaze command into 3-D eye and head commands with the use of three coordinated circuits: (1) a saccade generator, (2) a head rotation generator, (3) a VOR predictor. Simulations illustrate that the model can implement: (1) the correct 3-D reference frame transformations to generate accurate gaze shifts (despite variability in other parameters), (2) the experimentally verified constraints on static eye and head orientations during fixation, and (3) the experimentally observed 3-D trajectories of eye and head motion during gaze-shifts. We then use this model to simulate how 2-D eye-head coordination strategies interact with 3-D constraints to influence 3-D orientations of the eye-in-space, and the implications of this for spatial vision. PMID:26113816

  1. Saccadic compensation for smooth eye and head movements during head-unrestrained two-dimensional tracking.

    PubMed

    Daye, P M; Blohm, G; Lefèvre, P

    2010-01-01

    Spatial updating is the ability to keep track of the position of world-fixed objects while we move. In the case of vision, this phenomenon is called spatial constancy and has been studied in head-restraint conditions. During head-restrained smooth pursuit, it has been shown that the saccadic system has access to extraretinal information from the pursuit system to update the objects' position in the surrounding environment. However, during head-unrestrained smooth pursuit, the saccadic system needs to keep track of three different motor commands: the ocular smooth pursuit command, the vestibuloocular reflex (VOR), and the head movement command. The question then arises whether saccades compensate for these movements. To address this question, we briefly presented a target during sinusoidal head-unrestrained smooth pursuit in darkness. Subjects were instructed to look at the flash as soon as they saw it. We observed that subjects were able to orient their gaze to the memorized (and spatially updated) position of the flashed target generally using one to three successive saccades. Similar to the behavior in the head-restrained condition, we found that the longer the gaze saccade latency, the better the compensation for intervening smooth gaze displacements; after about 400 ms, 62% of the smooth gaze displacement had been compensated for. This compensation depended on two independent parameters: the latency of the saccade and the eye contribution to the gaze displacement during this latency period. Separating gaze into eye and head contributions, we show that the larger the eye contribution to the gaze displacement, the better the overall compensation. Finally, we found that the compensation was a function of the head oscillation frequency and we suggest that this relationship is linked to the modulation of VOR gain. We conclude that the general mechanisms of compensation for smooth gaze displacements are similar to those observed in the head-restrained condition. PMID

  2. Dynamic visual acuity testing for screening patients with vestibular impairments

    PubMed Central

    Peters, Brian T.; Mulavara, Ajitkumar P.; Cohen, Helen S.; Sangi-Haghpeykar, Haleh; Bloomberg, Jacob J.

    2013-01-01

    Dynamic visual acuity (DVA) may be a useful indicator of the function of the vestibulo-ocular reflex (VOR) but most DVA tests involve active head motion in the yaw plane. During gait the passive, vertical VOR may be more relevant and passive testing would be less likely to elicit compensatory strategies. The goal of this study was to determine if testing dynamic visual acuity during passive vertical motion of the subject would differentiate normal subjects from patients with known vestibular disorders. Subjects, normals and patients who had been diagnosed with either unilateral vestibular weaknesses or were post-acoustic neuroma resections, sat in a chair that could oscillate vertically with the head either free or constrained with a cervical orthosis. They viewed a computer screen 2 m away that showed Landholt C optotypes in one of 8 spatial configurations and which ranged in size from 0.4 to 1.0 logMAR. They were tested while the chair was stationary and while it was moving. Scores were worse for both groups during the dynamic condition compared to the static condition. In the dynamic condition patients’ scores were significantly worse than normals’ scores. Younger and older age groups differed slightly but significantly; the sample size was too small to examine age differences by decade. The data suggest that many well-compensated patients have dynamic visual acuity that is as good as age-matched normals. Results of ROC analyses were only moderate, indicating that the differences between patients and normals were not strong enough, under the conditions tested, for this test to be useful for screening people to determine if they have vestibular disorders. Modifications of the test paradigm may make it more useful for screening potential patients. PMID:23000614

  3. EyeSeeCam: an eye movement-driven head camera for the examination of natural visual exploration.

    PubMed

    Schneider, Erich; Villgrattner, Thomas; Vockeroth, Johannes; Bartl, Klaus; Kohlbecher, Stefan; Bardins, Stanislavs; Ulbrich, Heinz; Brandt, Thomas

    2009-05-01

    The prototype of a gaze-controlled, head-mounted camera (EyeSeeCam) was developed that provides the functionality for fundamental studies on human gaze behavior even under dynamic conditions like locomotion. EyeSeeCam incorporates active visual exploration by saccades with image stabilization during head, object, and surround motion just as occurs in human ocular motor control. This prototype is a first attempt to combine free user mobility with image stabilization and unrestricted exploration of the visual surround in a man-made technical vision system. The gaze-driven camera is supplemented by an additional wide-angle, head-fixed scene camera. In this scene view, the focused gaze view is embedded with picture-in-picture functionality, which provides an approximation of the foveated retinal content. Such a combined video clip can be viewed more comfortably than the saccade-pervaded image of the gaze camera alone. EyeSeeCam consists of a video-oculography (VOG) device and a camera motion device. The benchmark for the evaluation of such a device is the vestibulo-ocular reflex (VOR), which requires a latency on the order of 10 msec between head and eye (camera) movements for proper image stabilization. A new lightweight VOG was developed that is able to synchronously measure binocular eye positions at up to 600 Hz. The camera motion device consists of a parallel kinematics setup with a backlash-free gimbal joint that is driven by piezo actuators with no reduction gears. As a result, the latency between the rotations of an artificial eye and the camera was 10 msec, which is VOR-like. PMID:19645949

  4. Studying Cerebellar Circuits by Remote Control of Selected Neuronal Types with GABAA Receptors

    PubMed Central

    Wisden, William; Murray, Andrew J.; McClure, Christina; Wulff, Peer

    2009-01-01

    Although GABAA receptor-mediated inhibition of cerebellar Purkinje cells by molecular layer interneurons (MLIs) has been studied intensely at the cellular level, it has remained unclear how this inhibition regulates cerebellum-dependent behaviour. We have implemented two complementary approaches to investigate the function of the MLI-Purkinje cell synapse on the behavioural level. In the first approach we permanently disrupted inhibitory fast synaptic transmission at the synapse by genetically removing the postsynaptic GABAA receptors from Purkinje cells (PC-Δγ2 mice). We found that chronic disruption of the MLI-Purkinje cell synapse strongly impaired cerebellar learning of the vestibular occular reflex (VOR), presumably by disrupting the temporal patterns of Purkinje cell activity. However, in PC-Δγ2 mice the baseline VOR reflex was only mildly affected; indeed PC-Δγ2 mice show no ataxia or gait abnormalities, suggesting that MLI control of Purkinje cell activity is either not involved in ongoing motor tasks or that the system compensates for its loss. To investigate the latter possibility we developed an alternative genetic technique; we made the MLI-Purkinje cell synapse selectively sensitive to rapid manipulation with the GABAA receptor modulator zolpidem (PC-γ2-swap mice). Minutes after intraperitoneal zolpidem injection, these PC-γ2-swap mice developed severe motor abnormalities, revealing a substantial contribution of the MLI-Purkinje cell synapses to real time motor control. The cell-type selective permanent knockout of synaptic GABAergic input and the fast reversible modulation of GABAergic input at the same synapse illustrate how pursuing both strategies gives a fuller view. PMID:20076763

  5. Covert Anti-Compensatory Quick Eye Movements during Head Impulses

    PubMed Central

    Todd, Nicholas S.; Jahn, Klaus; Schneider, Erich; Lehnen, Nadine

    2014-01-01

    Background Catch-up saccades during passive head movements, which compensate for a deficient vestibulo-ocular reflex (VOR), are a well-known phenomenon. These quick eye movements are directed toward the target in the opposite direction of the head movement. Recently, quick eye movements in the direction of the head movement (covert anti-compensatory quick eye movements, CAQEM) were observed in older individuals. Here, we characterize these quick eye movements, their pathophysiology, and clinical relevance during head impulse testing (HIT). Methods Video head impulse test data from 266 patients of a tertiary vertigo center were retrospectively analyzed. Forty-three of these patients had been diagnosed with vestibular migraine, and 35 with Menière’s disease. Results CAQEM occurred in 38% of the patients. The mean CAQEM occurrence rate (per HIT trial) was 11±10% (mean±SD). Latency was 83±30 ms. CAQEM followed the saccade main sequence characteristics and were compensated by catch-up saccades in the opposite direction. Compensatory saccades did not lead to more false pathological clinical head impulse test assessments (specificity with CAQEM: 87%, and without: 85%). CAQEM on one side were associated with a lower VOR gain on the contralateral side (p<0.004) and helped distinguish Menière’s disease from vestibular migraine (p = 0.01). Conclusion CAQEM are a common phenomenon, most likely caused by a saccadic/quick phase mechanism due to gain asymmetries. They could help differentiate two of the most common causes of recurrent vertigo: vestibular migraine and Menière’s disease. PMID:24732783

  6. Physical Performance and a Test of Gaze Stabilization in Older Adults

    PubMed Central

    Ward, Bryan K.; Mohammed, Maha; Brach, Jennifer S.; Studenski, Stephane A.; Whitney, Susan L.; Furman, Joseph M.

    2010-01-01

    Objective The purpose of this study was to assess the feasibility of a standardized test of gaze stabilization as an indicator of vestibular function in community-dwelling older adults and to examine the relationship between gaze stabilization and physical performance. Design Descriptive, Cross-sectional. Setting Tertiary Medical Center. Subjects Eighty-six healthy older adults (22 males) of mean (SD) age 76.8 (5.8) years were recruited from the Pittsburgh community. Main Outcome Measures Performance on the gaze stabilization test (GST), measures of physical performance (standing balance, chair rises, and gait speed individually and combined into the Short Physical Performance Battery (SPPB)) and self-reported balance. Results While over 90% of participants completed testing in the pitch and yaw planes, only 85% (73/86) had interpretable scores, due to prolonged perception time, independent of VOR. The mean (SD) head movement velocity in the pitch plane was 94.5 (26.7) degrees per second and in the yaw plane was 95.5 (29.3) degrees per second. There was a strong association between age and GST performance in the pitch and yaw planes (r=0.68, p<0.001). Poor GST performance in the yaw plane was associated with balance capacity with eyes closed. Additionally, there was a trend toward an association between self-reported balance and GST performance in both pitch (p=0.08) and yaw planes (p=0.10). Conclusions While most older adults completed GST testing, estimates were not interpretable in almost 15% due to prolonged perception time. GST in the yaw plane was worse than previously reported in healthy older adults and was associated with poor ability to balance with eyes closed. Self-reported balance tended to be associated with an objective assessment of VOR in this population of older adults. PMID:19940791

  7. Next Generation Life Support Project: Development of Advanced Technologies for Human Exploration Missions

    NASA Technical Reports Server (NTRS)

    Barta, Daniel J.

    2012-01-01

    Next Generation Life Support (NGLS) is one of several technology development projects sponsored by the National Aeronautics and Space Administration s Game Changing Development Program. NGLS is developing life support technologies (including water recovery, and space suit life support technologies) needed for humans to live and work productively in space. NGLS has three project tasks: Variable Oxygen Regulator (VOR), Rapid Cycle Amine (RCA) swing bed, and Alternative Water Processing. The selected technologies within each of these areas are focused on increasing affordability, reliability, and vehicle self sufficiency while decreasing mass and enabling long duration exploration. The RCA and VOR tasks are directed at key technology needs for the Portable Life Support System (PLSS) for an Exploration Extravehicular Mobility Unit (EMU), with focus on prototyping and integrated testing. The focus of the Rapid Cycle Amine (RCA) swing-bed ventilation task is to provide integrated carbon dioxide removal and humidity control that can be regenerated in real time during an EVA. The Variable Oxygen Regulator technology will significantly increase the number of pressure settings available to the space suit. Current spacesuit pressure regulators are limited to only two settings while the adjustability of the advanced regulator will be nearly continuous. The Alternative Water Processor efforts will result in the development of a system capable of recycling wastewater from sources expected in future exploration missions, including hygiene and laundry water, based on natural biological processes and membrane-based post treatment. The technologies will support a capability-driven architecture for extending human presence beyond low Earth orbit to potential destinations such as the Moon, near Earth asteroids and Mars.

  8. Nonvisual complex spike signals in the rabbit cerebellar flocculus.

    PubMed

    Winkelman, Beerend H J; Belton, Tim; Suh, Minah; Coesmans, Michiel; Morpurgo, Menno M; Simpson, John I

    2014-02-26

    In addition to the well-known signals of retinal image slip, floccular complex spikes (CSs) also convey nonvisual signals. We recorded eye movement and CS activity from Purkinje cells in awake rabbits sinusoidally oscillated in the dark on a vestibular turntable. The stimulus frequency ranged from 0.2 to 1.2 Hz, and the velocity amplitude ranged from 6.3 to 50°/s. The average CS modulation was evaluated at each combination of stimulus frequency and amplitude. More than 75% of the Purkinje cells carried nonvisual CS signals. The amplitude of this modulation remained relatively constant over the entire stimulus range. The phase response of the CS modulation in the dark was opposite to that during the vestibulo-ocular reflex (VOR) in the light. With increased frequency, the phase response systematically shifted from being aligned with contraversive head velocity toward peak contralateral head position. At fixed frequency, the phase response was dependent on peak head velocity, indicating a system nonlinearity. The nonvisual CS modulation apparently reflects a competition between eye movement and vestibular signals, resulting in an eye movement error signal inferred from nonvisual sources. The combination of this error signal with the retinal slip signal in the inferior olive results in a net error signal reporting the discrepancy between the actual visually measured eye movement error and the inferred eye movement error derived from measures of the internal state. The presence of two error signals requires that the role of CSs in models of the floccular control of VOR adaption be expanded beyond retinal slip. PMID:24573280

  9. Right hemisphere dominance directly predicts both baseline V1 cortical excitability and the degree of top-down modulation exerted over low-level brain structures

    PubMed Central

    Arshad, Q.; Siddiqui, S.; Ramachandran, S.; Goga, U.; Bonsu, A.; Patel, M.; Roberts, R.E.; Nigmatullina, Y.; Malhotra, P.; Bronstein, A.M.

    2015-01-01

    Right hemisphere dominance for visuo-spatial attention is characteristically observed in most right-handed individuals. This dominance has been attributed to both an anatomically larger right fronto-parietal network and the existence of asymmetric parietal interhemispheric connections. Previously it has been demonstrated that interhemispheric conflict, which induces left hemisphere inhibition, results in the modulation of both (i) the excitability of the early visual cortex (V1) and (ii) the brainstem-mediated vestibular–ocular reflex (VOR) via top-down control mechanisms. However to date, it remains unknown whether the degree of an individual’s right hemisphere dominance for visuospatial function can influence, (i) the baseline excitability of the visual cortex and (ii) the extent to which the right hemisphere can exert top-down modulation. We directly tested this by correlating line bisection error (or pseudoneglect), taken as a measure of right hemisphere dominance, with both (i) visual cortical excitability measured using phosphene perception elicited via single-pulse occipital trans-cranial magnetic stimulation (TMS) and (ii) the degree of trans-cranial direct current stimulation (tDCS)-mediated VOR suppression, following left hemisphere inhibition. We found that those individuals with greater right hemisphere dominance had a less excitable early visual cortex at baseline and demonstrated a greater degree of vestibular nystagmus suppression following left hemisphere cathodal tDCS. To conclude, our results provide the first demonstration that individual differences in right hemisphere dominance can directly predict both the baseline excitability of low-level brain structures and the degree of top-down modulation exerted over them. PMID:26518461

  10. Dynamic visual acuity testing for screening patients with vestibular impairments.

    PubMed

    Peters, Brian T; Mulavara, Ajitkumar P; Cohen, Helen S; Sangi-Haghpeykar, Haleh; Bloomberg, Jacob J

    2012-01-01

    Dynamic visual acuity (DVA) may be a useful indicator of the function of the vestibulo-ocular reflex (VOR) but most DVA tests involve active head motion in the yaw plane. During gait the passive, vertical VOR may be more relevant and passive testing would be less likely to elicit compensatory strategies. The goal of this study was to determine if testing dynamic visual acuity during passive vertical motion of the subject would differentiate normal subjects from patients with known vestibular disorders. Subjects, normals and patients who had been diagnosed with either unilateral vestibular weaknesses or were post-acoustic neuroma resections, sat in a chair that could oscillate vertically with the head either free or constrained with a cervical orthosis. They viewed a computer screen 2 m away that showed Landholt C optotypes in one of 8 spatial configurations and which ranged in size from 0.4 to 1.0 logMAR. They were tested while the chair was stationary and while it was moving. Scores were worse for both groups during the dynamic condition compared to the static condition. In the dynamic condition patients' scores were significantly worse than normals' scores. Younger and older age groups differed slightly but significantly; the sample size was too small to examine age differences by decade. The data suggest that many well-compensated patients have dynamic visual acuity that is as good as age-matched normals. Results of ROC analyses were only moderate, indicating that the differences between patients and normals were not strong enough, under the conditions tested, for this test to be useful for screening people to determine if they have vestibular disorders. Modifications of the test paradigm may make it more useful for screening potential patients. PMID:23000614

  11. Differential Lateral Rectus Compartmental Contraction during Ocular Counter-Rolling

    PubMed Central

    Clark, Robert A.; Demer, Joseph L.

    2012-01-01

    Purpose. The lateral rectus (LR) and medial rectus (MR) extraocular muscles (EOMs) have largely nonoverlapping superior and inferior innervation territories, suggesting functional compartmental specialization. We used magnetic resonance imaging (MRI) in humans to investigate differential compartmental activity in the rectus EOMs during head tilt, which evokes ocular counter-rolling, a torsional vestibulo-ocular reflex (VOR). Methods. MRI in quasi-coronal planes was analyzed during target-controlled central gaze in 90° right and left head tilts in 12 normal adults. Cross sections and posterior partial volumes of the transverse portions of the four rectus EOMs were compared in contiguous image planes 2 mm thick spanning the orbit from origins to globe equator, and used as indicators of contractility. Results. Horizontal rectus EOMs had significantly greater posterior volumes and maximum cross sections in their inferior compartments (P < 10−8). In orbit tilt up (extorted) compared with orbit tilt down (intorted) head tilts, contractile changes in LR maximum cross section (P < 0.0001) and posterior partial volume (P < 0.05) were significantly greater in the inferior but not in the superior compartment. These changes were not explainable by horizontal or vertical eye position changes. A weaker compartmental effect was suggested for MR. The vertical rectus EOMs did not exhibit significant compartmental contractile changes during head tilt. Mechanical modeling suggests that differential LR contraction may contribute to physiological cyclovertical effects. Conclusions. Selective activation of the two LR, and possibly MR, compartments correlates with newly recognized segregation of intramuscular innervation into distinct compartments, and probably contributes to noncommutative torsion during the VOR. PMID:22427572

  12. Loss of Afferent Vestibular Input Produces Central Adaptation and Increased Gain of Vestibular Prosthetic Stimulation.

    PubMed

    Phillips, Christopher; Shepherd, Sarah J; Nowack, Amy; Nie, Kaibao; Kaneko, Chris R S; Rubinstein, Jay T; Ling, Leo; Phillips, James O

    2016-02-01

    Implanted vestibular neurostimulators are effective in driving slow phase eye movements in monkeys and humans. Furthermore, increases in slow phase velocity and electrically evoked compound action potential (vECAP) amplitudes occur with increasing current amplitude of electrical stimulation. In intact monkeys, protracted intermittent stimulation continues to produce robust behavioral responses and preserved vECAPs. In lesioned monkeys, shorter duration studies show preserved but with somewhat lower or higher velocity behavioral responses. It has been proposed that such changes are due to central adaptive changes in the electrically elicited vestibulo-ocular reflex (VOR). It is equally possible that these differences are due to changes in the vestibular periphery in response to activation of the vestibular efferent system. In order to investigate the site of adaptive change in response to electrical stimulation, we performed transtympanic gentamicin perfusions to induce rapid changes in vestibular input in monkeys with long-standing stably functioning vestibular neurostimulators, disambiguating the effects of implantation from the effects of ototoxic lesion. Gentamicin injection was effective in producing a large reduction in natural VOR only when it was performed in the non-implanted ear, suggesting that the implanted ear contributed little to the natural rotational response before injection. Injection of the implanted ear produced a reduction in the vECAP responses in that ear, suggesting that the intact hair cells in the non-functional ipsilateral ear were successfully lesioned by gentamicin, reducing the efficacy of stimulation in that ear. Despite this, injection of both ears produced central plastic changes that resulted in a dramatically increased slow phase velocity nystagmus elicited by electrical stimulation. These results suggest that loss of vestibular afferent activity, and a concurrent loss of electrically elicited vestibular input, produces an

  13. Differential adaptation of the linear and nonlinear components of the horizontal vestibuloocular reflex in squirrel monkeys

    NASA Technical Reports Server (NTRS)

    Clendaniel, Richard A.; Lasker, David M.; Minor, Lloyd B.; Shelhamer, M. J. (Principal Investigator)

    2002-01-01

    Previous work in squirrel monkeys has demonstrated the presence of linear and nonlinear components to the horizontal vestibuloocular reflex (VOR) evoked by high-acceleration rotations. The nonlinear component is seen as a rise in gain with increasing velocity of rotation at frequencies more than 2 Hz (a velocity-dependent gain enhancement). We have shown that there are greater changes in the nonlinear than linear component of the response after spectacle-induced adaptation. The present study was conducted to determine if the two components of the response share a common adaptive process. The gain of the VOR, in the dark, to sinusoidal stimuli at 4 Hz (peak velocities: 20-150 degrees /s) and 10 Hz (peak velocities: 20 and 100 degrees /s) was measured pre- and postadaptation. Adaptation was induced over 4 h with x0.45 minimizing spectacles. Sum-of-sines stimuli were used to induce adaptation, and the parameters of the stimuli were adjusted to invoke only the linear or both linear and nonlinear components of the response. Preadaptation, there was a velocity-dependent gain enhancement at 4 and 10 Hz. In postadaptation with the paradigms that only recruited the linear component, there was a decrease in gain and a persistent velocity-dependent gain enhancement (indicating adaptation of only the linear component). After adaptation with the paradigm designed to recruit both the linear and nonlinear components, there was a decrease in gain and no velocity-dependent gain enhancement (indicating adaptation of both components). There were comparable changes in the response to steps of acceleration. We interpret these results to indicate that separate processes drive the adaptation of the linear and nonlinear components of the response.

  14. Zu einer inhaltsorientierten Theorie des Lernens und Lehrens der biologischen Evolution

    NASA Astrophysics Data System (ADS)

    Wallin, Anita

    Der Zweck dieser Studie (zwecks Überblick siehe dazu Abb. 9.1) war zu untersuchen, wie die Schüler der Sekundarstufe II ein Verständnis von der Theorie der biologischen Evolution entwickeln. Vom Ausgangspunkt "Vorurteile der Schüler“ ausgehend wurden Unterrichtssequenzen entwickelt und drei verschiedene Lernexperimente in einem zyklischen Prozess durchgeführt. Das Wissen der Schüler wurde vor, während und nach den Unterrichtssequenzen mit Hilfe von schriftlichen Tests, Interviews und Diskussionsrunden in kleinen Gruppen abgefragt. Etwa 80 % der Schüler hatten vor dem Unterricht alternative Vorstellungen von Evolution, und in dem Nachfolgetest erreichten circa 75 % ein wissenschaftliches Niveau. Die Argumentation der Schüler in den verschiedenen Tests wurde sorgfältig unter Rücksichtnahme auf Vorurteile, der konzeptionellen Struktur der Theorie der Evolution und den Zielen des Unterrichts analysiert. Daraus konnten Einsichten in solche Anforderungen an Lehren und Lernen gewonnen werden, die Herausforderungen an Schüler und Lehrer darstellen, wenn sie anfangen, evolutionäre Biologie zu lernen oder zu lehren. Ein wichtiges Ergebnis war, dass das Verständnis existierender Variation in einer Population der Schlüssel zum Verständnis von natürlicher Selektion ist. Die Ergebnisse sind in einer inhaltsorientierten Theorie zusammengefasst, welche aus drei verschiedenen Aspekten besteht: 1) den inhaltsspezifischen Aspekten, die einzigartig für jedes wissenschaftliche Feld sind; 2) den Aspekten, die die Natur der Wissenschaft betreffen; und 3) den allgemeinen Aspekten. Diese Theorie kann in neuen Experimenten getestet und weiter entwickelt werden.

  15. Neural learning rules for the vestibulo-ocular reflex

    NASA Technical Reports Server (NTRS)

    Raymond, J. L.; Lisberger, S. G.

    1998-01-01

    Mechanisms for the induction of motor learning in the vestibulo-ocular reflex (VOR) were evaluated by recording the patterns of neural activity elicited in the cerebellum by a range of stimuli that induce learning. Patterns of climbing-fiber, vestibular, and Purkinje cell simple-spike signals were examined during sinusoidal head movement paired with visual image movement at stimulus frequencies from 0.5 to 10 Hz. A comparison of simple-spike and vestibular signals contained the information required to guide learning only at low stimulus frequencies, and a comparison of climbing-fiber and simple-spike signals contained the information required to guide learning only at high stimulus frequencies. Learning could be guided by comparison of climbing-fiber and vestibular signals at all stimulus frequencies tested, but only if climbing fiber responses were compared with the vestibular signals present 100 msec earlier. Computational analysis demonstrated that this conclusion is valid even if there is a broad range of vestibular signals at the site of plasticity. Simulations also indicated that the comparison of vestibular and climbing-fiber signals across the 100 msec delay must be implemented by a subcellular "eligibility" trace rather than by neural circuits that delay the vestibular inputs to the site of plasticity. The results suggest two alternative accounts of learning in the VOR. Either there are multiple mechanisms of learning that use different combinations of neural signals to drive plasticity, or there is a single mechanism tuned to climbing-fiber activity that follows activity in vestibular pathways by approximately 100 msec.

  16. Non-ovarian aromatization is required to activate female sexual motivation in testosterone-treated ovariectomized quail.

    PubMed

    de Bournonville, Catherine; Balthazart, Jacques; Ball, Gregory F; Cornil, Charlotte A

    2016-07-01

    Although aromatase is expressed in both male and female brains, its functional significance in females remains poorly understood. In female quail, sexual receptivity is activated by estrogens. However it is not known whether sexual motivation is similarly estrogen-dependent and whether estrogens locally produced in the brain contribute to these behavioral responses. Four main experiments were designed to address these questions. In Experiment 1 chronic treatment of females with the anti-estrogen tamoxifen decreased their receptivity, confirming that this response is under the control of estrogens. In Experiment 2 chronic treatment with tamoxifen significantly decreased sexual motivation as treated females no longer approached a sexual partner. In Experiment 3 (a) ovariectomy (OVX) induced a significant decrease of time spent near the male and a significantly decreased receptivity compared to gonadally intact females, (b) treatment with testosterone (OVX+T) partially restored these responses and (c) this effect of T was prevented when estradiol synthesis was inhibited by the potent aromatase inhibitor Vorozole (OVX+T+VOR). Serum estradiol concentration was significantly higher in OVX+T than in OVX or OVX+T+VOR females. Together these data demonstrate that treatment of OVX females with T increases sexual motivation and that these effects are mediated at least in part by non-gonadal aromatization of the androgen. Finally, assays of aromatase activity on brain and peripheral tissues (Experiment 4) strongly suggest that brain aromatization contributes to behavioral effects observed here following T treatment but alternative sources of estrogens (e.g. liver) should also be considered. PMID:27189762

  17. Pathogene Mikroorganismen

    NASA Astrophysics Data System (ADS)

    Wagner, Martin

    Infektionen, die vom Tier auf den Menschen übertragen werden, werden als Zoonosen bezeichnet. Pathogene Mikroorganismen können entweder durch Mensch-Mensch, Mensch-Tier-Kontakt oder durch Kontakt mit kontaminierten Vektoren übertragen werden [39]. Vektoren können einerseits belebt (z. B. blutsaugende Insekten), andererseits unbelebt sein. Kontaminierte Lebensmittel und Wasser gehören zu den wichtigsten unbelebten Vektoren. Neben Lebensmitteln können aber auch kontaminierte Gegenstände oder der Kontakt mit Kontaminationsquellen in der Umwelt Auslöser von Krankheitsfällen sein. Weltweit sind mehr als 1400 krankheitsverursachende biologische Agentien bekannt, von denen über 60 % ein zoonotisches Potenzial aufweisen. Als Ergebnis von Expertengesprächen wurde kürzlich berichtet, dass etwa 3 bis 4, meist virale, neu auftretende Infektionskrankheiten ("emerging diseases“) pro Jahr erwartet werden können [15]. Es handelt sich bei diesen Vorgängen aber nicht nur um das Auftauchen vollkommen neuer oder unbeschriebener Spezies, sondern auch um evolutionsbedingte Anpassungen von mikrobiellen Populationen an neue Bedingungen in ihrem Ökosystem [7]. Molekulare Analysen an Umweltchlamydien erbrachten Hinweise, dass die Evolution erste genetische Pathogenitätsmerkmale in dieser Spezies schon vor 700 Mio. Jahren entstehen ließ [14]. Viele Faktoren befeuern den Prozess der Anpassung, unter anderem auch alle Strategien, mit denen der Mensch seit Jahrtausenden versucht, Lebensmittel sicher und haltbar zu machen. Als die treibenden Kräfte des Auftretens neuer Krankheitserreger werden in der Gegenwart vor allem das sich ändernde Weltklima, die globalen Warenströme und die sich verändernden Konsumgewohnheiten genannt. Es steht auch außer Zweifel, dass viele dieser Erreger Tiere als ihr natürliches Reservoir haben werden, d. h. Zoonosen im klassischen Sinne sind [15].

  18. Right hemisphere dominance directly predicts both baseline V1 cortical excitability and the degree of top-down modulation exerted over low-level brain structures.

    PubMed

    Arshad, Q; Siddiqui, S; Ramachandran, S; Goga, U; Bonsu, A; Patel, M; Roberts, R E; Nigmatullina, Y; Malhotra, P; Bronstein, A M

    2015-12-17

    Right hemisphere dominance for visuo-spatial attention is characteristically observed in most right-handed individuals. This dominance has been attributed to both an anatomically larger right fronto-parietal network and the existence of asymmetric parietal interhemispheric connections. Previously it has been demonstrated that interhemispheric conflict, which induces left hemisphere inhibition, results in the modulation of both (i) the excitability of the early visual cortex (V1) and (ii) the brainstem-mediated vestibular-ocular reflex (VOR) via top-down control mechanisms. However to date, it remains unknown whether the degree of an individual's right hemisphere dominance for visuospatial function can influence, (i) the baseline excitability of the visual cortex and (ii) the extent to which the right hemisphere can exert top-down modulation. We directly tested this by correlating line bisection error (or pseudoneglect), taken as a measure of right hemisphere dominance, with both (i) visual cortical excitability measured using phosphene perception elicited via single-pulse occipital trans-cranial magnetic stimulation (TMS) and (ii) the degree of trans-cranial direct current stimulation (tDCS)-mediated VOR suppression, following left hemisphere inhibition. We found that those individuals with greater right hemisphere dominance had a less excitable early visual cortex at baseline and demonstrated a greater degree of vestibular nystagmus suppression following left hemisphere cathodal tDCS. To conclude, our results provide the first demonstration that individual differences in right hemisphere dominance can directly predict both the baseline excitability of low-level brain structures and the degree of top-down modulation exerted over them. PMID:26518461

  19. Nonvisual Complex Spike Signals in the Rabbit Cerebellar Flocculus

    PubMed Central

    Belton, Tim; Suh, Minah; Coesmans, Michiel; Morpurgo, Menno M.

    2014-01-01

    In addition to the well-known signals of retinal image slip, floccular complex spikes (CSs) also convey nonvisual signals. We recorded eye movement and CS activity from Purkinje cells in awake rabbits sinusoidally oscillated in the dark on a vestibular turntable. The stimulus frequency ranged from 0.2 to 1.2 Hz, and the velocity amplitude ranged from 6.3 to 50°/s. The average CS modulation was evaluated at each combination of stimulus frequency and amplitude. More than 75% of the Purkinje cells carried nonvisual CS signals. The amplitude of this modulation remained relatively constant over the entire stimulus range. The phase response of the CS modulation in the dark was opposite to that during the vestibulo-ocular reflex (VOR) in the light. With increased frequency, the phase response systematically shifted from being aligned with contraversive head velocity toward peak contralateral head position. At fixed frequency, the phase response was dependent on peak head velocity, indicating a system nonlinearity. The nonvisual CS modulation apparently reflects a competition between eye movement and vestibular signals, resulting in an eye movement error signal inferred from nonvisual sources. The combination of this error signal with the retinal slip signal in the inferior olive results in a net error signal reporting the discrepancy between the actual visually measured eye movement error and the inferred eye movement error derived from measures of the internal state. The presence of two error signals requires that the role of CSs in models of the floccular control of VOR adaption be expanded beyond retinal slip. PMID:24573280

  20. Effects of the Linear Vestibulo-ocular Reflex on Accommodative Vergence Eye Movements

    PubMed Central

    Yakushin, Sergei B.; Kunin, Mikhail; Ogorodnikov, Dmitri; Cohen, Bernard; Raphan, Theodore

    2016-01-01

    The aim of the study was to determine whether accommodation to the relative motion of a target along the visual axis of one eye during fore–aft movement of the head could induce accurate vergence over a wide range of viewing distances and frequencies of oscillation, despite lack of vision in the second eye. This was compared to the vergence when both eyes viewed the target. Two rhesus monkeys were trained to fixate a visual target located 216–336 mm in front and along the visual axis of one eye, while being sinusoidally translated in the fore–aft direction. There was no movement of the seeing eye while the other eye converged, regardless of whether there was vision in the converged eye. Gain and phase of the convergence were determined based on the ratio of actual versus expected eye position if the target was accurately fixated. During translation at frequencies from 0.05 to 2 Hz, the eye converged on the target with an eye position gain of ≈1, and a phase close to zero. When vision was occluded in the converging eye, gains of convergence were 0.6–0.8 Hz up to 2 Hz, and the phases remained close to zero. At low frequencies of fore–aft movement, when the acceleration was negligible, convergence was driven by accommodation in the seeing eye. At higher frequencies, vergence could also be driven by the linear vestibulo-ocular reflex (lVOR). Thus, vision in one nonmoving eye and the lVOR combine to generate convergence over a wide range of frequencies and viewing distances. PMID:19645957