CW) And Counterclockwise Rotation Research Articles

Coronary artery rotation in native and stented porcine coronary arteries.

Coronary arteries are exposed to several complex biomechanical forces during the cardiac cycle. These biomechanical forces potentially contribute to both native coronary artery disease, development of atherosclerosis and eventual stent failure. The aim of the present study was to characterize and define coronary artery axial rotation and the effect of stent implantation on this biomechanical factor. Intravascular ultrasound (IVUS) images were obtained from porcine coronary arteries and analyzed in ultrasound analysis software used to evaluate myocardial strain and torsion in echocardiography. In this study the software was utilized for a novel application to evaluate coronary artery rotation and time-to-peak (TTP) rotation in porcine coronary arteries. Clockwise (CW) and counterclockwise (CCW) rotation of coronary arteries during the cardiac cycle and (TTP) rotation were measured. A total of 11 (4 LAD, 4 LCX, 3 RCA) coronary artery segments were independently analyzed pre- and post-stent implantation for a total of 22 IVUS runs. CW and CCW rotation and TTP varied widely within coronary artery segments and between different coronary arteries. Stent implantation impacted degree, direction and TTP of coronary rotation. Measurement reliability was assessed and the intraclass correlation coefficient for maximum average CCW was 0.990 (95% confidence interval 0.980-0.996, P < 0.0001), indicating excellent agreement. Coronary arteries display wide spectrum of CW and CCW rotation during the cardiac cycle. Coronary stents impact the degree and direction of coronary artery rotation. The implications of these findings on development of atherosclerosis and stent failure require further investigation.

On the Horizontal Deviation of a Spinning Projectile Penetrating into Granular Systems

The absence of a general theory that describes the dynamical behavior of the particulate materials makes the numerical simulations the most current powerful tool that can grasp many mechanical problems relevant to the granular materials. In this paper, based on a two-dimensional soft particle discrete element method (DEM), a numerical approach is developed to investigate the consequence of the orthogonal impact into various granular beds of projectile rotating in both clockwise (CW) and counterclockwise (CCW) directions. Our results reveal that, depending on the rotation direction, there is a significant deviation of the x-coordinate of the final stopping point of a spinning projectile from that of its original impact point. For CW rotations, a deviation to the right occurs while a left deviation has been recorded for CCW rotation case.

Determination of magnetic anisotropy constants and domain wall pinning energy of Fe/MgO(001) ultrathin film by anisotropic magnetoresistance.

It is challenging to determine domain wall pinning energy and magnetic anisotropy since both coherent rotation and domain wall displacement coexist during magnetization switching process. Here, angular dependence anisotropic magnetoresistance (AMR) measurements at different magnetic fields were employed to determine magnetic anisotropy constants and domain wall pinning energy of Fe/MgO(001) ultrathin film. The AMR curves at magnetic fields which are high enough to ensure the coherent rotation of magnetization indicate a smooth behavior without hysteresis between clockwise (CW) and counter-clockwise (CCW) rotations. By analyzing magnetic torque, the magnetic anisotropy constants can be obtained. On the other hand, the AMR curves at low fields show abrupt transitions with hysteresis between CW and CCW rotations, suggesting the presence of multi-domain structures. The domain wall pinning energy can be obtained by analyzing different behaviors of AMR. Our work suggests that AMR measurements can be employed to figure out precisely the contributions of magnetic anisotropy and domain wall pinning energy, which is still a critical issue for spintronics.

Asymmetry in the clockwise and counterclockwise rotation of the bacterial flagellar motor

Cells of Escherichia coli are able to swim up gradients of chemical attractants by modulating the direction of rotation of their flagellar motors, which spin alternately clockwise (CW) and counterclockwise (CCW). Rotation in either direction has been thought to be symmetric and exhibit the same torques and speeds. The relationship between torque and speed is one of the most important measurable characteristics of the motor, used to distinguish specific mechanisms of motor rotation. Previous measurements of the torque-speed relationship have been made with cells lacking the response regulator CheY that spin their motors exclusively CCW. In this case, the torque declines slightly up to an intermediate speed called the "knee speed" after which it falls rapidly to zero. This result is consistent with a "power-stroke" mechanism for torque generation. Here, we measure the torque-speed relationship for cells that express large amounts of CheY and only spin their motors CW. We find that the torque decreases linearly with speed, a result remarkably different from that for CCW rotation. We obtain similar results for wild-type cells by reexamining data collected in previous work. We speculate that CCW rotation might be optimized for runs, with higher speeds increasing the ability of cells to sense spatial gradients, whereas CW rotation might be optimized for tumbles, where the object is to change cell trajectories. But why a linear torque-speed relationship might be optimum for the latter purpose we do not know.

Paleomagnetism of Tertiary intrusive and volcaniclastic rocks of the Cerrillos Hills and surrounding region, Española Basin, New Mexico, U.S.A.: Assessment and implications of vertical-axis rotations associated with extension of the Rio Grande rift

Paleomagnetic data from parts of the northern Rio Grande rift provide evidence for clockwise (CW) and counterclockwise (CCW) vertical-axis block rotations associated with strike-slip deformation along basin-bounding faults during rift evolution. Despite the spatial consistency of the results, the quality and statistical significance of data sets are difficult to evaluate because of small sample size and potential failure to average secular variation. To understand the extent, importance, and origin of such rotations, we report paleomagnetic data from Tertiary intrusive and volcaniclastic rocks in the Cerrillos Hills and surrounding areas in the Espanola Basin. Paleomagnetic data from in situ Tertiary intrusions and tilt-corrected volcaniclastic strata of the Oligocene Espinaso Formation sampled at four localities yield a grand mean of declination = 342.9° and inclination = 58.3° (α 95 = 3.5°; N = 32 sites of normal polarity/21 reverse). Correction for minor postemplacement tilt of the Cerrillos Hills and La Cienega data sets yields a grand mean (declination = 349.5°, inclination = 55.3°, α 95 = 3.4°) that is indistinguishable from the 30 Ma reference direction for the study area, and there is no evidence of rotation (R = 1.8° ± 6.4°). However, if an alternative reference direction is used, minor CCW rotation (−6.6° ± 5.8°) is possible. Our data suggest that the magnitude of rotation in the Espanola Basin is significantly less than previously estimated and may be negligible. Regardless, paleomagnetic data from elsewhere in the basin suggest that CCW rotations may be an important component of recent rift extension and deformation.

Modal analysis and proof of a novel ultrasonic motor

In this paper, a novel disc-type Ultrasonic Motor (UM) stator is investigated. The stator has an asymmetrical structure (120°-90°-150° support boundary configuration) on its surface. It is mainly focused on description of the disc-type UM structure and operation principle from a published patent. Then according to the patent's modal analysis and test and adding our laser vibrometer measurement of mode motion and wave propagation concept, the asymmetrical simple-support boundary configuration for an adaptive mechanism will be able to be proven. The relationship between contact point (rotor location) and Clockwise (CW) and Counter-Clockwise (CCW) rotation and the relationship between frequency and CW and CCW rotation will also be proven by finite element mode interaction together with real inspection. The driving circuit and measured characteristics for the motor system are also discussed.

Partition Efficiencies of an Eccentric Coiled Separation Column for Centrifugal Partition Chromatography

The partition efficiency of an eccentric coiled separation column, newly fabricated in our laboratory, was studied using centrifugal partition chromatography (CPC) with four different two‐phase solvent systems including n‐hexane‐acetonitrile; tert‐butyl methyl ether‐aqueous 0.1% trifluoroacetic acid (1∶1); 1‐butanol‐water (1∶1); and 12.5% (w/w) polyethylene glycol 1000–12.5% (w/w) dibasic potassium phosphate. Each separation was performed by eluting either the upper phase in the ascending mode or the lower phase in the descending mode, each in clockwise and counterclockwise (CCW) column rotation. Better partition efficiencies were attained by the CCW rotation in both mobile phases in all the two‐phase solvent systems examined. The overall results demonstrated that the coiled separation column yielded substantially higher partition efficiencies than the commercial disk column. The eccentric coiled separation column is useful for the separation by CPC.

Convergence of directional vestibular and neck signals on cerebellar purkinje cells.

Convergence of spatially oriented vestibular and neck signals within the cerebellar anterior vermis in decerebrate cats was studied by recording the simple spike discharge of Purkinje (P) cells during wobble either of the whole animal (vestibular input) or of the body under a fixed head (neck input) at 0.156 Hz, 5 degrees and 2.5 degrees , respectively. Both clockwise (CW) and counterclockwise (CCW) rotations were performed. Units that had equal response amplitudes to CW and CCW rotations (narrowly tuned neurons) were described by a single vector (Smax), characterized by a gain, a direction and a temporal phase. Units with different response amplitudes to CW and CCW rotation (broadly tuned neurons) were described by two vectors (Smax and Smin). In addition to these bidirectional units, there were also unidirectional units which responded either to CW or CCW rotation; in these cases the gain of Smax equals that of Smin. On the whole, 77% and 63% of the P cells responding to vestibular and neck stimulation, respectively, showed a bidirectional broadly tuned or unidirectional behavior. These response patterns were attributed to the convergence of signals with different spatial and temporal properties. About 50% of the P cells from which recordings were made responded to stimulation of both sensory systems. However, the gains of the Smax vectors of the neck responses were much greater than those of the vestibular responses, at least for small amplitudes of rotation, and were positively correlated with them. Usually the differences in the orientation components of the neck and vestibular Smax vectors were larger, while the differences in temporal phases were smaller than 90 degrees . These findings suggest that periodic changes in the phase difference and gain ratio of the neck to the vestibular response may occur during dynamic displacement of the head over the body, depending on the stimulus direction. As a result of these data, the P cells of the cerebellar vermis are expected to show prominent responses to head rotation, which could affect the spatially organized postural responses by utilizing vestibular and reticular targets.

Response of medial medullary reticular neurons to otolith stimulation during bidirectional off-vertical axis rotation of the cat

In decerebrate cats, the extracellular activities of neurons in the medial medullary reticular formation were studied during constant velocity off-vertical axis rotations (OVAR) in the clockwise (CW) and counterclockwise (CCW) directions (at 10° tilt). Spontaneously active neurons demonstrated sinusoidal position-dependent discharge modulations to OVAR which selectively stimulates the otoliths. Two features of neuronal responses to bidirectional OVAR were identified. Within the velocity spectrum tested (1.75–15° /s), some neurons showed symmetric bidirectional response sensitivity (δ value) to CW and CCW rotations. The spread of the δ values of each of these neurons with velocity was small. This group of reticular neurons were described as exhibiting symmetric and velocity-stable bidirectional response sensitivity. The mathematically derived gain tuning ratios of these neurons were within the range of narrowly spatiotemporal-tuned neurons. Another group of reticular neurons, however, showed asymmetric bidirectional response sensitivity to CW and CCW rotations; a few of these neurons were responsive only to OVAR of one direction but not to both. For each of this second group of neurons, the spread of the δ values with velocity was large. These reticular neurons were described as exhibiting asymmetric and velocity-variable bidirectional response sensitivity. The gain tuning ratios of these latter neurons were found to be within the range of broadly spatiotemporal-tuned neurons. Single neurons of both groups displayed orientational tuning. Both the best response orientations of neurons that showed symmetric and velocity-stable bidirectional response sensitivity and the preferred orientations of neurons that showed asymmetric and velocity-variable bidirectional response sensitivity were found to point in all directions on the rotary plane. The response dynamics of the former group of neurons was also examined. All showed flat response gain across the entire velocity range. Some showed a flat response lead while others showed a progressive shift from small response lead at low velocity to phase close to zero at higher velocities. The functional significance of these medial medullary reticular neurons to the direction and orientation of head tilt is discussed.

Torsional properties of stainless steel and nickel-titanium endodontic files

The torsional properties of stainless steel (SS) endodontic files (Flex-O-File; Maillefer/L. D. Caulk Co., Milford, DE) and recently developed nickel-titanium (NiTi) endodontic files (Quality Dental Products, Inc., Johnson City, TN) were compared. File sizes 15, 25, 35, 45, and 55 were subjected to torsional load in clockwise (CW) and counterclockwise (CCW) directions independently. Results showed that SS files had a significantly greater rotation to failure in the CW direction, whereas the NiTi files had a significantly greater rotation to failure in the CCW direction. Despite these differences in rotation to fracture, there was essentially no difference between the SS and NiTi instruments in the torque that it took to cause failure in both the CW and the CCW directions. Therefore, whereas the number of CW and CCW rotations to failure differed for the two instruments, the actual force that it took to cause that failure was the same.

Responses of Purkinje cells in the cerebellar anterior vermis to off-vertical axis rotation.

Responses of 67 Purkinje cells (P-cells) and 44 unidentified neurons (U-cells) located in the cerebellar anterior vermis were recorded in decerebrate cats during off-vertical axis rotation (OVAR). This stimulus consisted of a slow constant velocity (9.4%/s) rotation in the clockwise (CW) and counterclockwise (CCW) directions around an axis inclined by 5 degrees with respect to the vertical. OVAR imposes on the animal head a 5 degrees tilt, whose direction changes continuously over the horizontal plane, thus eliciting a selective stimulation of macular receptors. A total of 27/67 P-cells (40%) and 24/44 U-cells (55%) responded to both CW and CCW rotations. For these bidirectional units, the direction of maximum sensitivity to tilt (Smax) could be identified. Smax directions were distributed over the whole horizontal plane of stimulation. Among bidirectional neurons, 48% of the P-cells and 33% of the U-cells displayed an equal amplitude of modulation during CW and CCW rotations, indicating a cosine-tuned behaviour. In these instances, the temporal phase of the unit response to a given direction of tilt remained constant, while the sensitivity was maximal along the Smax direction and declined with the cosine of the angle between Smax and the tilt direction. The remaining bidirectional units displayed unequal amplitudes of modulation during CW and CCW rotations. For these neurons, a nonzero sensitivity along the null direction was expected and the response phase varied as a function of stimulus direction. Finally, 31% and 23% of P-cells and U-cells, respectively, responded during OVAR in one direction only (unidirectional units). This behaviour predicts equal sensitivities along any tilt direction in the horizontal plane and a response phase that changes linearly with the stimulus direction. The posibility that the tested neurons formed a population which coded the direction of head tilt in space was also investigated. The data from the whole population of cells were analysed using a modified version of vectorial analysis. This model assumes that for a particular tilt each cell makes vectorial contributions; the vectorial sum of these contributions represent the outcome of the population code and points in the direction of head tilt in space. Thus, a dynamic head tilt along four representative directions was simulated. For each of the four directions, 12 population vectors were calculated at regular time intervals so as to cover an entire cycle of head tilt. The results indicate that for each selected time in the cycle the direction of the population vector closely corresponded to that of the head tilt, while its amplitude was related to the amount of head tilt. These data were particularly obtained for the P-cells. In view of their efferent connections, the cerebellar anterior vermis may provide a framework for the spatial organization of vestibulospinal reflexes induced by stimulation of otolith receptors.

Properties of otolith-related vestibular nuclear neurons in response to bidirectional off-vertical axis rotation of the rat

In decerebrate rats, the responses of tilt-sensitive neurons in the lateral and descending vestibular nuclei were studied during constant velocity 10° off-vertical axis rotations (OVAR) in the clockwise (CW) and counterclockwise (CCW) directions. Sevety three otolith-related units showed sinusoidal position-dependent discharge modulation to OVAR of both directions; 20 of these showed clipped firing rates in parts of a 360° OVAR cycle. With increase in the velocity of rotation (1.75-15°/s), one group of units ( n = 36) showed a stable ratio of bidirectional response sensitivity and symmetric response magnitudes to CW and CCW rotations. These units showed gain tuning ratios similar to those of narrowly spatiotemporal-tuned neurons. The other group of OVAR responsive units ( n = 13) exhibited velocity-variable and asymmetric bidirectional response sensitivities. Their gain tuning ratios were similar to those of broadly spatiotemporal-tuned neurons. For units with velocity-stable and symmetric bidirectional response sensitivity as well as gain tuning ratio of the narrowly spatiotemporal-tuned neurons, their response gains remained stable with velocity. Some showed stable response phase lead or lag with velocity increase while others showed progressive shifts from response lead of 13° to response lag of −25°. The best response orientations of these units with velocity-stable and symmetric bidirectional response sensitivity were found to point in all directions on the plane of rotation. The functional significance of these tilt- and OVAR-sensitive central otolith neurons is discussed.

Torsional properties of the canal master instrument

The torsional properties of a new type of endodontic hand instrument, the Canal Master, were compared with conventional machined K-type endodontic files. Sizes 20 through 50 were tested in clockwise (CW) and counterclockwise (CCW) directions. Canal Master instruments exhibited significantly less torque at yield and at failure in both the CW and CCW directions. Rotation at failure was significantly greater for the Canal Master instruments in both CW and CCW directions. There was no significant difference in either torque or the amount of rotation for the Canal Master instruments when comparing CW versus CCW rotation. There was no clinically visible evidence of deformation of the Canal Master instruments prior to torsional failure.

Uniform Daily Rotation and Biological Rhythms and Clocks in Hamsters

The mean forms of 24-h circadian patterns of 12 male hamsters differed as a function of the clock hour of dark onsets in 24 h (12:12) light-dark cycles, independently of time of year. The forms of activity cycles for dark onset at 18:00 CST for three 3-mo periods, at three different times of year and including the first and third years, were strikingly similar to one another and moderately similar to cycles with dark onset at noon but were significantly different from cycles with dark onset at hours 24:00 and 6:00. The latter two were also different from one another. A very high correlation is seen for all series, between concurrent-cycle forms obtained on a stationary table and on tables rotating uniformly clockwise (CW) and counterclockwise (CCW) at 1 rpd. Uniform daily CW and CCW rotations (from above) effect a small phase delay in circadian cycles phase synchronized to imposed 12:12 light/dark (LD) cycles set to various times of day. A major minimum occurs during the first hours of darkness, a major m...