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Journal of Neurophysiology May 1975We studied the responses of 34 deefferented spindle receptors to slowly applied ramp stretches (0.01-1 mm/s) of small (0.02-0.2 mm) and intermediate (0.2-1 mm)...
We studied the responses of 34 deefferented spindle receptors to slowly applied ramp stretches (0.01-1 mm/s) of small (0.02-0.2 mm) and intermediate (0.2-1 mm) amplitudes. The afferent discharge from primary and secondary endings was recorded from filaments of dorsal root in anesthetized cats. 1. Responses of most endings to ramps of intermediate amplitude showed abrupt changes in slope (discontinuities) which were highly repeatable. Discontinuities occurred more nearly at constant stretch (in the range 50-400 mum for different receptors) than at constant discharge rate. They were less pronounced in the case of secondary endings. 2. Changes in sensitivity occurred when the degree of stretch exceeded a transitional amplitude which ranged from 50 to 200 mum. These changes were studied by constructing plots based on a family of responses to a family of ramps which were scaled versions of each other. The plots indicated that reductions in sensitivity occurred both during stretch and during adaptation; the reductions were more marked for primary than for secondary endings. 3. Responses were modified considerably by preceding changes in muscle length. When the last change was an increase of a few millimeters, discontinuities became more pronounced and other changes in the appearance of the dynamic response occurred, particularly in the case of primary endings. These changes could last for several minutes, but were abolished by a single test stretch of intermediate amplitude. 4. The resetting of high sensitivity that occurs when muscle length is changed, the discontinuities, the transitions in sensitivity, nonlinear adaptation, and the effects of previous length change appeared to be related phenomena. They can all be accounted for by the hypothesis that polar zones of intrafusal muscle fibers possess a frictionlike property, one analogous to that which has been described for whole muscle. A simple nonlinear model which shows these features is presented. 5. The adequate stimulus for a change in primary ending discharge is a small change in muscle length, relatively independently of its velocity. The dynamic response arises mainly from a changing sensitivity to length itself, which is a nonlinear property.
Topics: Animals; Cats; Denervation; Differential Threshold; Evoked Potentials; Mathematics; Models, Neurological; Muscle Spindles; Neurons, Efferent; Physical Stimulation
PubMed: 123952
DOI: 10.1152/jn.1975.38.3.673 -
Chaos (Woodbury, N.Y.) Sep 2018Bouncing fluid droplets can walk on the surface of a vibrating bath forming a wave-particle association. Walking droplets have many quantum-like features. Research...
Bouncing fluid droplets can walk on the surface of a vibrating bath forming a wave-particle association. Walking droplets have many quantum-like features. Research efforts are continuously exploring quantum analogues and respective limitations. Here, we demonstrate that two oscillating particles (millimetric droplets) confined to separate potential wells exhibit correlated dynamical features, even when separated by a large distance. A key feature is the underlying wave mediated dynamics. The particles' phase space dynamics is given by the system as a whole and cannot be described independently. Numerical phase space histograms display statistical coherence; the particles' intricate distributions in phase space are statistically indistinguishable. However, removing one particle changes the phase space picture completely, which is reminiscent of entanglement. The model here presented also relates to nonlinearly coupled oscillators where synchronization can break out spontaneously. The present oscillator-coupling is dynamic and can change intensity through the underlying wave field as opposed to, for example, the Kuramoto model where the coupling is pre-defined. There are some regimes where we observe phase-locking or, more generally, regimes where the oscillators are statistically indistinguishable in phase-space, where numerical histograms display their (mutual) most likely amplitude and phase.
PubMed: 30278623
DOI: 10.1063/1.5050805 -
Science (New York, N.Y.) Nov 1972Polystyrene spherules averaging 0.5 millimeter in diameter (range 0.1 to 2 millimeters) are abundant in the coastal waters of southern New England. Two types are...
Polystyrene spherules averaging 0.5 millimeter in diameter (range 0.1 to 2 millimeters) are abundant in the coastal waters of southern New England. Two types are present, a crystalline (clear) form and a white, opaque form with pigmentation resulting from a diene rubber. The spherules have bacteria on their surfaces and contain polychlorinated biphenyls, apparently absorbed from ambient seawater, in a concentration of 5 parts per million. White, opaque spherules are selectively consumed by 8 species of fish out of 14 species examined, and a chaetognath. Ingestion of the plastic may lead to intestinal blockage in smaller fish.
Topics: Animals; Bacteria; Connecticut; Digestive System; Fishes; Massachusetts; Polychlorinated Biphenyls; Polystyrenes; Rhode Island; Spectrophotometry, Infrared; Water Microbiology; Water Pollution, Chemical
PubMed: 4628343
DOI: 10.1126/science.178.4062.749 -
Journal of Pediatric Ophthalmology and... 1980In ten normal subjects we measured the angular rotations of the globe, both in adduction and in abduction, corresponding to limbus shifts from 1 to 7 mm. Our study...
In ten normal subjects we measured the angular rotations of the globe, both in adduction and in abduction, corresponding to limbus shifts from 1 to 7 mm. Our study demonstrated that to each millimeter of temporal limbus shift corresponds an average adduction of about 4.6 degrees and to each millimeter of nasal limbus shift an average abduction of about 4.8 degrees. These experimental results give a sound foundation to the clinical evaluation of the strabismic angle by measuring, with a millimeter ruler, the limbus shift of the nonfixating eye by assuming fixation. This technique appears particularly useful as a substitute for the simultaneous prism and cover test, in the evaluation of a squint with a variable angle, and in measurements in other positions of gaze.
Topics: Adolescent; Adult; Child; Female; Fixation, Ocular; Humans; Male; Optical Rotation; Strabismus
PubMed: 7441447
DOI: 10.3928/0191-3913-19800901-16 -
Anticancer Research 2002The effects of low power millimetric wave (MMW) radiation on the growth of tumor and healthy cells were studied. A wide-band frequency range between 53.57-78.33 GHz with...
The effects of low power millimetric wave (MMW) radiation on the growth of tumor and healthy cells were studied. A wide-band frequency range between 53.57-78.33 GHz with a radiation density power of 27 x 10(-17) watt/Hz were used. The radiating energy was low enough not to increase the temperature of the cellular samples (cold irradiation). One hour of radiation treatment given every other day to three tumoral human stable cell lines, produced a noticeable inhibition of the cellular growth. The analogous treatment given to two healthy cell lines gave a weak growth stimulation. A scanning electron microscopy study of MCF-7-and K562-irradiated cells revealed that MMW irradiation induced profound morphological changes of the membrane. Finally, we also provided a mechanistic indication, based on millimeter wave spectroscopy of the cells: water is the primary absorber of these electromagnetic waves. Our work provides interesting evidence that wide band low power MMW irradiation, in the appropriate frequency range, could be used in the future as a cold means to cause selective inhibition of tumor cell growth.
Topics: Breast Neoplasms; Cell Division; Electromagnetic Fields; Humans; K562 Cells; Tumor Cells, Cultured
PubMed: 12168854
DOI: No ID Found -
ACS Central Science May 2022Assembling nanoparticles to spatially well-defined functional nanomaterials and sophisticated architectures has been an intriguing goal for scientists. However,...
Assembling nanoparticles to spatially well-defined functional nanomaterials and sophisticated architectures has been an intriguing goal for scientists. However, maintaining a long-range order of assembly to create macrostructures remains a challenge, owing to the reliance on purely interparticle interactions. Here, we present a general strategy to synthesize a class of inorganic nanosheets via a bottom-up directional freezing method. We demonstrate that, by confining a homogeneously dispersed metal-cyano colloidal suspension at the ice-water interface, followed by removal of ice crystals, large nanosheets with a lateral scale of up to several millimeters can be produced. The formation of millimeter-sized nanosheets is attributed to balanced electrostatic forces between dispersed nanoparticles, coupled with an appropriate hydrodynamic size of nanoparticles, potentially favorable lattice matching between nanoparticles and ice crystals, and the intermediate water at the ice-particle interface. The highly anisotropic growth of ice crystals can therefore guide the 2D confined assembly of nanoparticles in a long-range order, leading to well-defined 2D nanosheets. This contribution sheds light on the potential of nanoparticle assembly at larger length scales in designing families of large 2D nanoarchitectures for practical applications.
PubMed: 35647283
DOI: 10.1021/acscentsci.2c00252 -
Bioengineering (Basel, Switzerland) Dec 2023For the past three decades, neurosurgeons have utilized cranial neuro-navigation systems, bringing millimetric accuracy to operating rooms worldwide. These systems...
For the past three decades, neurosurgeons have utilized cranial neuro-navigation systems, bringing millimetric accuracy to operating rooms worldwide. These systems require an operating room team, anesthesia, and, most critically, cranial fixation. As a result, treatments for acute neurosurgical conditions, performed urgently in emergency rooms or intensive care units on awake and non-immobilized patients, have not benefited from traditional neuro-navigation. These emergent procedures are performed freehand, guided only by anatomical landmarks with no navigation, resulting in inaccurate catheter placement and neurological deficits. A rapidly deployable image-guidance technology that offers highly accurate, real-time registration and is capable of tracking awake, moving patients is needed to improve patient safety. The Zeta Cranial Navigation System is currently the only non-fiducial-based, FDA-approved neuro-navigation device that performs real-time registration and continuous patient tracking. To assess this system's performance, we performed registration and tracking of phantoms and human cadaver heads during controlled motions and various adverse surgical test conditions. As a result, we obtained millimetric or sub-millimetric target and surface registration accuracy. This rapid and accurate frameless neuro-navigation system for mobile subjects can enhance bedside procedure safety and expand the range of interventions performed with high levels of accuracy outside of an operating room.
PubMed: 38135992
DOI: 10.3390/bioengineering10121401 -
IEEE Transactions on Ultrasonics,... Jul 2010A novel method is presented for investigation of the traveling wave propagation generated on a thin film pipe with a short length of several millimeters. As a bridge to...
A novel method is presented for investigation of the traveling wave propagation generated on a thin film pipe with a short length of several millimeters. As a bridge to connect two piezoelectric ceramic (lead zirconate titanate, PZT) tubes, a thin-film metallic glass (TFMG) pipe is fabricated by a new technique of rotating magnetron sputtering. The vibrator combines the vibration of the axial mode of the PZT tube and the radial mode of the TFMG pipe. Theoretical analyses of the TFMG pipe and PZT tube, with a comparison of the finite element modeling, clarify the vibration characteristics so that the proper geometrical sizes, suitable boundary conditions, and driving voltage signals are designed. In the experiment, the designed vibrator was fabricated and the vibration characteristics were measured by a laser Doppler vibrometer system. The pure traveling wave propagation obtained theoretically and experimentally demonstrates the validity of this work. This study shows a new way to achieve a pure traveling wave on a short cylindrical pipe driven by PZT tubes.
PubMed: 20639154
DOI: 10.1109/TUFFC.2010.1590 -
Optics Express May 2022Laser excitation based on the thermoelastic principle is effective for micro-scale actuation, enabled energy conversion from optical to mechanical. The major advantages...
Laser excitation based on the thermoelastic principle is effective for micro-scale actuation, enabled energy conversion from optical to mechanical. The major advantages lie in non-contact actuation, easy miniaturization, and integration. To avoid surface damage, the laser power per unit is limited, leading to several micrometers of the vibration. In this study, a pure nickel millimeter-sized cantilever is successfully actuated at a low-frequency resonance (around Hz) via a nanosecond pulsed laser. By modal interaction, the energy is transferred from a low-intensity, high-frequency (around kHz) excitation to a low-frequency response with millimeter amplitude. The stable low-frequency resonance of the cantilever was maintained by changing the laser pulse parameters and the illumination locations. We also present a method to control the vibration of the cantilever using a modulated wave (MW: the laser wave modulated by a rectangular wave). The cantilever's amplitude can be efficiently adjusted by changing the laser power or duty cycle of the MW. The resonance frequency of the cantilever also can be altered by optimizing the geometries to meet various actuation requirements. This study enables large actuation (up to tens of millimeters) by laser excitation, facilitating applications in precision manipulation, microfluidic mixing, lab-on-a-chip device, and other related micro actuation devices.
PubMed: 36221701
DOI: 10.1364/OE.451454 -
Analytical Chemistry Sep 2022We propose an all-optical miniaturized multigas simultaneous detection photoacoustic (PA) sensor, which is primarily composed of a copper tube, a silica cantilever, and...
We propose an all-optical miniaturized multigas simultaneous detection photoacoustic (PA) sensor, which is primarily composed of a copper tube, a silica cantilever, and four single-mode fibers. Three single-mode fibers are used as excitation fibers to transmit lasers of different wavelengths, and the remaining one is used as a probe fiber. The volumes of the PA cell (PAC) and the sensor are 36 μL and 71 cubic millimeters, respectively. A laser photoacoustic spectroscopy (PAS) system, using the all-optical miniaturized PA sensor as a detector, 1532.8, 1576.3, and 1653.7 nm distributed feedback (DFB) lasers as the excitation sources for acetylene (CH), hydrogen sulfide (HS), and methane (CH) gases, and a high-speed spectrometer as a demodulator, has been developed for multigas simultaneous measurements. The minimum detection limits of 4.8, 162, and 16.6 parts per billion (ppb) have been achieved for CH, HS, and CH, respectively, with an integration time of 100 s. The reported sensor shows a potential for high-sensitivity multigas simultaneous measurements in cubic millimeter-scale space.
PubMed: 36043800
DOI: 10.1021/acs.analchem.2c02767