75 research outputs found
PhysicsâInformed Neural Networks to Model and Control Robots: A Theoretical and Experimental Investigation
This work concerns the application of physicsâinformed neural networks to the modeling and control of complex robotic systems. Achieving this goal requires extending physicsâinformed neural networks to handle nonconservative effects. These learned models are proposed to combine with modelâbased controllers originally developed with firstâprinciple models in mind. By combining standard and new techniques, precise control performance can be achieved while proving theoretical stability bounds. These validations include realâworld experiments of motion prediction with a soft robot and trajectory tracking with a Franka Emika Panda manipulator.</jats:p
Longitudinal Results With Intratympanic Dexamethasone in the Treatment of MĂ©niĂšreâs Disease
To assess patient satisfaction with vertigo control using
intratympanic (IT) dexamethasone (12 mg/mL) for medically refractory unilateral
Meniere's disease. STUDY DESIGN: Retrospective study. SETTING: Tertiary referral
neurotology clinic. PATIENTS: One hundred twenty-nine subjects diagnosed with
unilateral Meniere's disease still having vertigo despite medical therapy.
INTERVENTION: IT dexamethasone injections as needed to control vertigo attacks.
MAIN OUTCOME MEASURE: A Kaplan-Meier time-to-event method was used to determine
the rate of "survival," meaning sufficient satisfaction with vertigo control that
the subject did not wish to have subsequent ablative treatment. "Failure" was
defined as poor control and the choice to proceed to ablative treatment. RESULTS:
Acceptable vertigo control ("survival") was achieved in 117 (91%) of 129
subjects. Vertigo control required only one dexamethasone injection in 48 (37%),
2 injections in 26 (20%), 3 injections in 18 (14%), and 4 injections in 10 (8%).
More than 4 injections were needed in 15 subjects (21%). Of 12 failures (9%), 9
occurred within 6 months of the first IT dexamethasone injection. Follow-up data
for 2 years were available for 96 subjects. Of these, 87 (91%) had vertigo
control with IT dexamethasone, of whom 61 (70)% required no further injections
after 2 years, 23 (26%) continued to receive IT dexamethasone injections, and 3
(3%) chose IT gentamicin treatment. CONCLUSION: IT dexamethasone injection
therapy on an as-needed outpatient basis can provide vertigo control that is
satisfactory in patients with Meniere's disease. The Kaplan-Meier method
addresses the need for an outcome measure suited to repeated treatments and
variable lengths of follow-up. However, due to the retrospective nature of this
study, the presence of bias caused by loss of subjects from follow-up cannot be
ruled out
Modeling and Simulation of Hybrid Soft Robots Using Finite Element Methods: Brief Overview and Benefits
Obliteration of radical cavities with autogenous cortical bone; long-term results
<p>Abstract</p> <p>Background</p> <p>To evaluate the long-term surgical outcome(s) in patients who have undergone canal-wall-down operation with mastoid and epitympanic obliteration using autologous cortical bone chips, bone pate and meatally-based musculoperiosteal flap technique.</p> <p>Method</p> <p>Retrospective evaluation of seventy patients operated during 1986â1991 due to a cholesteatoma. An otomicroscopy was performed to evaluate the postoperative outer ear canal configuration with a modified Likert scale (1 â 4). The outer ear canal physical volume was assessed by tympanometry. The hearing outcome and a patient-filled questionnaire were also analyzed.</p> <p>Results</p> <p>The posterior wall results were 1.8 (± 0.9 SD) and the attic region 1.8 (± 0.9 SD) (ns., p > 0.05). These values show either no cavity formation or minor formation of a cavity, with a good functional result. The mean volume of the operated ear canal was 1.7 (± 0.5 SD) ml. The volume of the contralateral ear canal was 1.2 (± 0.3 SD) ml (*** p < 0.0001). A comparison of the current mean ABG to the preoperative mean ABG and to the ABG at one-year postoperatively, 5-years postoperatively or 10-years postoperatively showed no statistical significance (p > 0.05).</p> <p>Conclusion</p> <p>ABG does not significantly change in the long-term. The configuration of the cavity tends to change, however, the obliteration material is stable in the long-term and clinically significant cavitation rarely occurs.</p
Peaks and Troughs of Three-Dimensional Vestibulo-ocular Reflex in Humans
The three-dimensional vestibulo-ocular reflex (3D VOR) ideally generates compensatory ocular rotations not only with a magnitude equal and opposite to the head rotation but also about an axis that is collinear with the head rotation axis. Vestibulo-ocular responses only partially fulfill this ideal behavior. Because animal studies have shown that vestibular stimulation about particular axes may lead to suboptimal compensatory responses, we investigated in healthy subjects the peaks and troughs in 3D VOR stabilization in terms of gain and alignment of the 3D vestibulo-ocular response. Six healthy upright sitting subjects underwent whole body small amplitude sinusoidal and constant acceleration transients delivered by a six-degree-of-freedom motion platform. Subjects were oscillated about the vertical axis and about axes in the horizontal plane varying between roll and pitch at increments of 22.5° in azimuth. Transients were delivered in yaw, roll, and pitch and in the vertical canal planes. Eye movements were recorded in with 3D search coils. Eye coil signals were converted to rotation vectors, from which we calculated gain and misalignment. During horizontal axis stimulation, systematic deviations were found. In the light, misalignment of the 3D VOR had a maximum misalignment at about 45°. These deviations in misalignment can be explained by vector summation of the eye rotation components with a low gain for torsion and high gain for vertical. In the dark and in response to transients, gain of all components had lower values. Misalignment in darkness and for transients had different peaks and troughs than in the light: its minimum was during pitch axis stimulation and its maximum during roll axis stimulation. We show that the relatively large misalignment for roll in darkness is due to a horizontal eye movement component that is only present in darkness. In combination with the relatively low torsion gain, this horizontal component has a relative large effect on the alignment of the eye rotation axis with respect to the head rotation axis
Age dependent normal horizontal VOR gain of head impulse test as measured with video-oculography
High-Pass Filtering of Input Signals by the Ih Current in a Non-Spiking Neuron, the Retinal Rod Bipolar Cell
Hyperpolarizationâactivated cyclic nucleotideâsensitive (HCN) channels mediate the If current in heart and Ih throughout the nervous system. In spiking neurons Ih participates primarily in different forms of rhythmic activity. Little is known, however, about its role in neurons operating with graded potentials as in the retina, where all four channel isoforms are expressed. Intriguing evidence for an involvement of Ih in early visual processing are the side effects reported, in dim light or darkness, by cardiac patients treated with HCN inhibitors. Moreover, electroretinographic recordings indicate that these drugs affect temporal processing in the outer retina. Here we analyzed the functional role of HCN channels in rod bipolar cells (RBCs) of the mouse. Perforatedâpatch recordings in the darkâadapted slice found that RBCs exhibit Ih, and that this is sensitive to the specific blocker ZD7288. RBC input impedance, explored by sinusoidal frequencyâmodulated current stimuli (0.1â30 Hz), displays bandâpass behavior in the range of Ih activation. Theoretical modeling and pharmacological blockade demonstrate that highâpass filtering of input signals by Ih, in combination with lowâpass filtering by passive properties, fully accounts for this frequencyâtuning. Correcting for the depolarization introduced by shunting through the pipetteâmembrane seal, leads to predict that in darkness Ih is tonically active in RBCs and quickens their responses to dim light stimuli. Immunohistochemistry targeting candidate subunit isoforms HCN1â2, in combination with markers of RBCs (PKC) and rodâRBC synaptic contacts (bassoon, mGluR6, Kv1.3), suggests that RBCs express HCN2 on the tip of their dendrites. The functional properties conferred by Ih onto RBCs may contribute to shape the retina's light response and explain the visual side effects of HCN inhibitors
Inhibition of the classical pathway of the complement cascade prevents early dendritic and synaptic degeneration in glaucoma
A field technique for recording the activity of limpets
ABSTRACT A field technique for recording both temporal and spatial parameters of activity in limpets was tested on a Tyrrhenian population of Patella rustica Linnaeus which shows definite homing behaviour. Timing of foraging excursions was recorded using reed switches activated by a magnet glued to the shell apex. The 'at home-away' status of each animal was continuously screened throughout one month by interfacing the sensors with a computer. Moreover, individual excursions were minutely reconstructed by using a motographic technique which combined LED-tracking (nocturnal activity) and instantaneous photography (daytime movements). An original wave-meter was designed to monitor the sea-status during the study period. The quality of the temporal and spatial data obtained with this technique is evaluated, and further improvements of the technique are discussed
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