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PubMed2006

[Rotational malalignment causing patellofemoral complications after total knee replacement].

OBJECTIVE: To study the rotation of femoral component and tibial component with CT and evaluate the relationship between patellofemoral complications and rotational alignment of the components. METHODS: Thirty patients with isolated patellofemoral complications after total knee arthroplasty were compared with 20 patients with well functioning total knee replacements free of patellofemoral complications. The epicondylar axis and tibial tubercle were used as references on CT scans to quantify the rotational alignment of the femoral and tibial components. RESULTS: Patients with patellofemoral complications had excessive combined (tibial plus femoral) internal component rotation, which was directly proportional to the severity of the patellofemoral complications. Mild combined internal rotation (1 degree-4 degrees) was correlated with patellar and lateral tracking tilting, moderate rotation (3 degrees-8 degrees) with patellar subluxation, and severe rotation (7 degrees-17 degrees) with early patellar dislocation or late patellar prosthesis failure. The control group had combined external rotation of 10 degrees-0 degree. CONCLUSIONS: The direct correlation of combined internal component rotation to the severity of the patellofemoral complication suggests that internal component rotation may be the predominant cause of patellofemoral complications in patients with normal axis alignment. CT scans can be used intraoperatively and postoperatively to determine whether the rotational malalignment is present to require revision of one or both components.

Adult↗
PubMed2006

[Immobilization in external rotation after primary shoulder dislocation].

INTRODUCTION: The standard method of treating acute primary dislocation of the glenohumeral joint is immobilization of the arm in adduction and internal rotation with a sling. The recurrence rate for anterior instability after nonoperative treatment in young active patients is extremely high (up to 90%) and well reported. A new method of immobilization with the arm in external rotation improves the position of the displaced labrum on the glenoid rim. With the use of control MRI before and after immobilization in external rotation, a study on this new repositioning of the labrum is evaluated. METHODS: Ten patients (mean age 30.4 years) with primary anterior dislocation of the shoulder and Bankart lesion as shown on MRI but with no hyperlaxity of the contralateral side were immobilized in 10-20 degrees of external rotation for 3 weeks. Scans with MRI were taken in internal and external shoulder rotation post trauma and in internal rotation after 6 weeks. All patients were reevaluated after 6 and 12 months. RESULTS: Dislocation and separation of the labrum were both significantly less with the arm in external rotation due to the tension of the anterior capsule and the tendon of the subscapularis muscle. In the MRI taken in internal rotation 6 weeks post trauma, all Bankart lesions were fixed in reposition after three weeks of immobilization in external rotation. At 12-month follow-up, the average Constant Score was 96.1 points (range 63-100), and the Rowe Score was 91.5 points (range 25-100). One patient had traumatic redislocation after 8 months. CONCLUSION: After primary shoulder dislocation, immobilizing the arm in 10-20 degrees external rotation provided stable fixation of the Bankart lesion in an anatomic position. First long-term indications from an ongoing prospective study of recurrence rates after immobilization in external rotation are promising.

Adolescent↗
PubMed2001

Dynamic visual acuity during passive and self-generated transient head rotation in normal and unilaterally vestibulopathic humans.

To determine whether dynamic visual acuity (DVA) during head rotations on the stationary body can lateralize unilateral vestibular deafferentation and detect non-labyrinthine compensation mechanisms, 15 normal and 11 subjects with unilateral vestibular deafferentation underwent manually imposed and self-generated transient yaw head rotations during measurement of binocular DVA. DVA was measured by a four-alternative, forced choice, staircase procedure with optotype presentation only when head velocity exceeded thresholds of 50 degree or 75 degree/s. Eye and head movements were recorded using search coils to characterize ocular motor strategies. During directionally unpredictable, manually imposed contralesional rotation, unilaterally deafferented subjects had decreases in DVA from the static condition of 0.36 +/- 0.22 and 0.47 +/- 0.53 log of the minimum angle resolvable (logMAR, mean +/- SD), respectively, for 50 degree and 75 degree/s thresholds, not significantly greater than those of normal subjects (0.26 +/- 0.13 and 0.36 +/- 0.14, P>0.05). However, during manually imposed ipsilesional rotation, vestibulopathic subjects had decreases in DVA of 0.66 +/- 0.36 and 1.08 +/- 0.47 logMAR, significantly greater than during contralesional rotation ( P<0.01). The DVA reduction difference for the ipsi- and contralesional directions was less during self-generated than during manually imposed head rotations. The directional difference for manually administered head rotations yielded a robust diagnostic measure with essentially no overlap in performance with normal subjects. Diagnostic performance for DVA during self-generated head rotation was poorer. Recordings of eye and head movements made using search coils during DVA testing confirmed a deficient vestibulo-ocular reflex (VOR) during ipsilesional rotation, with most unilaterally vestibulopathic subjects employing predictive smooth eye movements and vestibular catch-up saccades. Measurement of DVA during transient head rotation on the body thus reliably can detect and lateralize vestibular pathology and compensatory mechanisms. Extravestibular mechanisms for compensation appear more effective during self-generated than manually imposed head rotations.

Adolescent↗
PubMed1994

Barrel rotation induced by central arginine8-vasopressin treatment: involvement of neurohypophyseal peptide receptors.

Two series of experiments were done to investigate the mechanism underlying arginine8-vasopressin (AVP)-induced barrel rotation in rats. In the first series, the effect of intracerebroventricular (ICV) administration of various neurohypophyseal hormone antagonists on AVP-induced barrel rotation was studied. The more vasopressin was given, the more the rats exhibited barrel rotation. ICV pretreatment with a V1 vasopressin receptor antagonist, d(CH2)5[Tyr(Me)2]AVP, prevented barrel rotation, while similar treatment with a V2-antagonist, d(CH2)5[dIle2Ile4]AVP, did not affect vasopressin-induced barrel rotation. However, Des-Gly,NH2d(CH2)5[Tyr)Me2)Thr4Orn8]-vasotocin, a specific oxytocin antagonist, potentiated the effect of AVP on barrel rotation. The second experiment was performed in rats equipped with a telemetry system to measure heart rate (HR), core temperature (CT), and gross locomotor activity. Also, in this experiment the incidence of AVP-induced barrel rotation was dose-dependent, as was the number of rats that died. Barrel rotation was accompanied by a significant decrease in CT and HR, while rats that did not develop hypothermia did not show barrel rotation. These results suggest that a V1 receptor is involved in barrel rotation. Since AVP-induced hypothermia is also mediated by a V1 receptor, it is postulated that hypothermia is a prerequisite for barrel rotation to occur. Further experiments are needed to substantiate this hypothesis.

Animals↗
PubMed1995

The effects of out-of-plane rotations on two dimensional portal image registration in conformal radiotherapy of the prostate.

PURPOSE: Rotations of the patient out of the image plane can significantly degrade the accuracy of two-dimensional (2D) image registration. This study determines the magnitude of the geometric errors introduced by 2D image registration as a result of out-of-plane rotations, and analyzes the dosimetric effects of these errors. METHODS AND MATERIALS: The magnitude of the errors introduced by 2D registration were determined by comparing orthogonal view portal images of a rotated phantom to simulator reference images of the same phantom without rotation. Dosimetric effects were calculated for three-dimensional (3D) conformal prostate treatments by applying the registration errors to patient treatment plans. The calculations were performed using a modified version of the dose calculation software used in our Cancer Center for 3D treatment planning based on computed tomography (CT). A method to detect out-of-plane rotations, specific to pelvic treatments, is introduced that uses the relative displacement of the centers of gravity of the acetabula in lateral images. RESULTS: The inherent uncertainty in the registration algorithm was 0.6 +/- 0.5 mm in translation and 0.7 +/- 0.8 degree in rotation within the image plane. For a 2 degrees out-of-plane rotation, the errors increase to 2.3 +/- 1.0 mm and 1.2 +/- 1.1 degrees. In some clinically realizable treatment scenarios it was observed that the errors introduced by the registration procedure could result in an overdosing of the rectal wall. The method to detect out-of-plane rotations was found to have an accuracy of better than 1 degree for rotations of less than 10 degrees. CONCLUSIONS: The errors introduced to the patient position by 2D image registration have dosimetrically significant consequences for out-of-plane rotations of 2 degrees or more. However, when used in conjunction with the method to detect out-of-plane rotations, 2D registration software was found to cause insignificant dose errors and, thus, become a more reliable and accurate clinical tool.

Humans↗
PubMed2004

Motional narrowing of the rotational spectrum of trifluoropropyne at 6550 cm(-1) by intramolecular vibrational energy redistribution.

We present the basic principles of dynamic rotational spectroscopy for the highly vibrationally excited symmetric top molecule trifluoropropyne (TFP,CF3CCH). Single molecular eigenstate rotational spectra of TFP were recorded in the region of the first overtone of the nu(1) acetylenic stretching mode at 6550 cm(-1) by infrared-pulsed microwave-Fourier transform microwave triple resonance spectroscopy. The average rotational constant (B) of the highly vibrationally mixed quantum states at 6550 cm(-1) is 2909.33 MHz, a value that is 40 MHz larger than the rotational constant expected for the unperturbed C-H stretch overtone (2869.39 MHz). The average rotational constant and rotational line shape of the molecular eigenstate rotational spectra are compared to the distribution of rotational constants expected for the ensemble of normal-mode vibrational states at 6550 cm(-1) that can interact by intramolecular vibrational energy redistribution (IVR). The normal-mode population distribution at 6550 cm(-1) can be described using a Boltzmann distribution with a microcanonical temperature of 1200 K. At this energy the rotational constant distribution in the normal-mode basis set is peaked at about 2910 MHz with a width of about 230 MHz. The distribution is slightly asymmetric with a tail to the high end. The experimentally measured dynamic rotational spectra are centered at the normal-mode distribution peak; however, the spectral width is significantly narrower (40 MHz) than normal-mode ensemble width (230 MHz). This reduction of the width, along with the Lorentzian shape of the eigenstate rotational spectra when compared to the Gaussian shape of the calculated ensemble distribution, illustrates the narrowing of the spectrum due to IVR exchange. The IVR exchange rate was determined to be 120 ps, about ten times faster than the rate at which energy is redistributed from the v=2 level of the acetylenic stretch.

Journal Article↗
PubMed2006

Rotational transitions and diffraction in D2 scattering from the LiF(001) surface: theory and experiment.

High probabilities of energy transfer from translation to molecular rotations are observed in the scattering of n-D(2) from LiF(001) at an incident beam energy of 85.3 meV. For the 100 incidence direction, close-coupling calculations yield ratios of the rotationally inelastic (j=0-->2) and (j=1-->3) peaks to the rotationally elastic specular peaks (G=0) that are in reasonable agreement with experiment, as are the ratios of the rotationally elastic diffraction peak intensities to the specular peak intensities. The agreement between theory and experiment is also quite good for the rotationally inelastic diffractive (-1-1) transitions for (j=1-->3), but rather poor for (j=0-->2). The calculations show that the interaction between the electrostatic field of the surface ions and the quadrupole moment of the D(2) molecule efficiently promotes the (j=0-->2) and (j=1-->3) transitions. If this electrostatic interaction is excluded from the potential model, the ratios of the (j=0-->2) and (j=1-->3) rotationally inelastic peaks to the corresponding specular peaks show a large discrepancy with experiment, underlining the importance of this interaction. The close-coupling calculations show a somewhat worse agreement with experiment for the 110 incidence direction. In particular, the sharp peaks observed experimentally in the ratios of the peak intensities of the rotationally inelastic G=0 (j=0-->2) and (j=1-->3) to the rotationally elastic G=0 transitions as a function of incident angle are not reproduced by the calculations. The theoretical ratios of the peak intensities of the rotationally elastic diffraction to G=0 transitions are shifted to lower incidence angles with respect to experiment. The rotationally inelastic diffractive (-10) transitions present an interesting resonance phenomenon for the (j=0-->2) rotational transition. This resonance is predicted by both theory and experiment, although at rather different incident angles.

Journal Article↗
PubMed2001

Tibiofemoral conformity and kinematics of rotating-bearing knee prostheses.

Increasing tibiofemoral articular conformity theoretically increases articular contact area and reduces contact stresses in total knee arthroplasty. Fixed-bearing knee designs possess relatively low tibiofemoral conformity, in part to allow tibiofemoral rotation without generating excessive stresses at the articulation or the implant-bone interface. This study analyzed knee kinematics of mobile-bearing designs in a closed chain dynamic knee extension model in posterior cruciate-retaining design with high- and low tibiofemoral conformity and posterior cruciate-substituting designs with and without rotational constraint. Overall, for all conditions, the mobile-bearing insert rotated with the femur in the presence of tibiofemoral axial rotation. In addition, the correlation of bearing rotation with femoral rotation was stronger for the high-conformity and rotationally-constrained designs than for the low-conformity designs and strongest for the posterior cruciate-retaining high-conformity condition. Changes in conformity or rotational constraint did not appear to affect femoral roll back, tibiofemoral axial rotation, or varus-valgus angulation. The results suggest that mobile-bearing inserts rotate with the femur and increasing conformity or rotational constraint in mobile-bearing design knee prostheses does not affect knee kinematics adversely, at least under closed chain knee extension conditions in vitro.

Biomechanical Phenomena↗
PubMed2002

Prenatal rotation of the lumbar spine and its relevance for the development of the zygapophyseal joints.

STUDY DESIGN: The intrauterine axial rotational characteristics of the lumbar spine were analyzed and quantified sonographically. OBJECTIVES: To determine whether axial rotational movements of the lumbar spine occur prenatally, which may influence the morphogenesis of the zygapophysial joints. SUMMARY OF BACKGROUND DATA: Previously, the development of lumbar zygapophysial sagittal joint orientation was linked to the increase in torque of the torso as upright posture and locomotion are adopted. However, the potential influence of prenatal axial rotational movement of the lumbar spine on the development of the zygapophysial joints has not been examined. METHODS: For this study, 52 healthy fetuses, gestation age 9 to 36 weeks, were monitored sonographically for rotational movements of the lumbar spine. By multiplanar reconstruction of the sonography images, exemplary segmental rotational values were acquired. This method was validated by directly measuring the manually induced rotation of the formalin-fixated fetus in addition to multiplanar reconstruction. RESULTS: Axial rotations of the lumbar spine were seen in most of the examined fetuses ages 9 to 36 gestation weeks. Rotations are best assessable with multiplanar reconstruction in the second trimenon, when segmental rotation of the lower lumbar spine reaches a mean of 8 degrees (range, 4-10 degrees ). CONCLUSIONS: Fetal axial rotation of the lower lumbar spine reaches a degree that may functionally influence the morphologic development of the articular processes of the zygapophysial joints. In contrast to the prevalent hypothesis, lumbar spine development is already functionally influenced prenatally by axial rotation.

Embryonic and Fetal Development↗
PubMed1987

Effect of an adolescent medicine rotation on pelvic examination skills of paediatric residents.

This study evaluated the effects of an adolescent medicine rotation on paediatric residents' pelvic examination skills. Measurements were: self-evaluations pre- and post-rotation; nurse's evaluations of pelvic examination performance during the first and last week of the rotation; and patients' evaluations. The self-evaluation was also given at the start and at the end of the year to residents not taking the rotation. Twenty-four third-year residents were evaluated during the year. Eighteen subjects taking the rotation showed significant improvement post-rotation in the areas of competence, comfort, evaluation of training and importance to career, while the six residents not taking the rotation showed no change. The nurse's evaluation of the pelvic examination showed increases in comfort level, skill, awareness of adolescents' feelings, and ability to explain and reassure. Patient ratings were high at the beginning of the rotation and showed no significant change post-rotation. An adolescent medicine rotation significantly improved pelvic examination skills as assessed by self-ratings and a nurse's evaluation. A rotation in adolescent medicine can play a crucial role in developing gynaecological skills in paediatric residents.

Adolescent Medicine↗
PubMed1984

Direction of flagellar rotation in bacterial cell envelopes.

Cell envelopes with functional flagella, isolated from wild-type strains of Escherichia coli and Salmonella typhimurium by formation of spheroplasts with penicillin and subsequent osmotic lysis, demonstrate counterclockwise (CCW)-biased rotation when energized with an electron donor for respiration, DL-lactate. Since the direction of flagellar rotation in bacteria is central to the expression of chemotaxis, we studied the cause of this bias. Our main observations were: (i) spheroplasts acquired a clockwise (CW) bias if instead of being lysed they were further incubated with penicillin; (ii) repellents temporarily caused CW rotation of tethered bacteria and spheroplasts but not of their derived cell envelopes; (iii) deenergizing CW-rotating cheV bacteria by KCN or arsenate treatment caused CCW bias; (iv) cell envelopes isolated from CW-rotating cheC and cheV mutants retained the CW bias, unlike envelopes isolated from cheB and cheZ mutants, which upon cytoplasmic release lost this bias and acquired CCW bias; and (v) an inwardly directed, artificially induced proton current rotated tethered envelopes in CCW direction, but an outwardly directed current was unable to rotate the envelopes. It is concluded that (i) a cytoplasmic constituent is required for the expression of CW rotation (or repression of CCW rotation) in strains which are not defective in the switch; (ii) in the absence of this cytoplasmic constituent, the motor is not reversible in such strains, and it probably is mechanically constricted so as to permit CCW sense of rotation only; (iii) the requirement of CW rotation for ATP is not at the level of the motor or the switch but at one of the preceding functional steps of the chemotaxis machinery; (iv) the cheC and cheV gene products are associated with the cytoplasmic membrane; and (v) direct interaction between the switch-motor system and the repellent sensors is improbable.

Cell Fractionation↗
PubMed2000

Factors associated with hip joint rotation in former elite athletes.

OBJECTIVES: To study factors associated with passive hip rotation range of motion (ROM) in former elite male athletes. METHODS: Athletes were interviewed about hip pain, disability, lifetime occupational loading, and athletic training. The passive hip rotation was measured with a Myrin inclinometer in 117 former elite male long distance runners, soccer players, weight lifters, and shooters aged 45-68 years. Magnetic resonance imaging was used to detect hip osteoarthritis. RESULTS: There were no differences in passive hip rotation ROM between the four athlete groups nor between diverging lifetime loading patterns associated with occupational or athletic activities. Among the subjects without hip osteoarthritis, hip pain, and hip disability according to a stepwise linear regression analysis, the only factor that was associated with the passive hip rotation ROM was body mass index (BMI), explaining about 21% of its variation. Subjects with high BMI had lower passive hip rotation ROM than those with low BMI. There was no right-left difference in the mean passive hip rotation ROM in subjects either with or without hip osteoarthritis as determined by magnetic resonance imaging. Nevertheless, hip rotation ROM was clearly reduced in a few hips with severe caput deformity. CONCLUSIONS: Long term loading appears to have no association with passive hip rotation ROM. On the other hand, the hip rotation value was lower in subjects with high BMI than in those with low BMI. A clear right-left difference in hip rotation was found only in those subjects who, according to our magnetic resonance imaging criteria, had severe hip osteoarthritis. These findings should be taken into account when hip rotation ROM is used in the clinical assessment of hip joints.

Aged↗
PubMed1993

High frequency rotational ablation: an alternative in treating coronary artery stenoses and occlusions.

OBJECTIVE: To prove the safety and effectiveness of high frequency rotational ablation of coronary artery stenoses and occlusion in humans. SUBJECTS: 106 patients with symptoms (91 men, 15 women) who had 67 significant stenoses, mainly types B and C, and 46-chronic occlusions. MAIN OUTCOME MEASURES: Mean change in diameter stenosis after rotational angioplasty alone and in combination with percutaneous transluminal coronary angioplasty immediately after treatment and 24 hours and six months later; restenosis rates at six months; complication of treatment. RESULTS: Rotational ablation could not be used in five stenoses and 16 chronic occlusions because of inability to reach or cross the lesion with the Rotablator guide wire. In four cases rotational ablation failed. Initial angiographic and clinical success by rotational ablation was achieved in 40 of the 67 stenoses (60%) and in 18 of the 46 chronic occlusions (39%). Additional balloon angioplasty was performed in 45 patients, increasing the success rates to 79% and 54%, respectively. In the 62 stenoses treated by rotational ablation the angiographic diameter stenoses were reduced from 76% (SD 14%) to 32% (14%) after Rotablator treatment alone and from 75% (11%) to 33% (17%) with additional balloon angioplasty. In the 30 chronic occlusions treated by rotational ablation the angiographic diameter stenoses were reduced to 38% (18%). At six months angiographic restenosis was evident in nine of the 25 (36%) stenoses treated with rotational ablation alone, in seven of the 22 (32%) stenoses treated with rotational and balloon angioplasty, and in 14 of the 24 (58%) chronic occlusions. There were no procedural deaths and two patients (2%) underwent emergency coronary artery bypass grafting. Although no transmural infarction occurred, there were five (6%) non-Q wave infarctions (two embolic side branch occlusions, two subacute occlusions, and one acute occlusion). Clinically insignificant slight increases in creatine kinase activity were seen in five patients (6%). Severe coronary artery spasm unresponsive to medical treatment was provoked in seven cases (8%). CONCLUSIONS: High frequency rotational ablation is a safe and effective method for treating type B and C coronary artery lesions with results comparable to percutaneous transluminal coronary balloon angioplasty. The combined use of rotational ablation and balloon angioplasty is feasible and is necessary in about half of all procedures, in most cases because the lumen created by the biggest burr is too small.

Adult↗
PubMed2003

Mental rotation of perspective stimuli in a California sea lion (Zalophus californianus).

The time it takes humans to discriminate rotated objects from their mirror images increases linearly with the rotation angle. This phenomenon is probably due to an analogue mode of visual information processing during which an object's mental representation is rotated in a time-consuming process called mental rotation. As the speed of mental rotation in humans depends on rotation axis, we tested the ability of a California sea lion to mentally rotate perspective line drawings of three-dimensional objects about four axes. In a matching-to-sample experiment the animal was presented with the image and a mirror image of a block sample that had previously been shown upright. Both image and mirror image were rotated by a multiple of 60 degrees about the object's x-, y-, z-axis, or a skew axis (an axis oblique to these standard orthogonal axes). The animal's choice and reaction times were recorded using a computer-controlled touch-screen device. Mean reaction times and errors generally increased with angular disparity supporting the model of mental rotation for three-dimensional objects. Linear regression analysis of mean reaction times yielded high correlation coefficients only for three axes. The slope of reaction time functions indicated the highest mental rotation speed for the skew axis. This contrasts with the priority of mental rotation axes in humans suggesting that due to special ecological demands a different mode of orientation invariance evolved in marine mammals.

Animals↗
PubMed2006

Path of glenohumeral articulation throughout the rotational range of motion in a thrower's shoulder model.

BACKGROUND: Overhead-throwing athletes have increased external and diminished internal glenohumeral rotation that may alter glenohumeral kinematics. PURPOSE: To quantify the kinematic changes present in a cadaveric model of a thrower's shoulder. STUDY DESIGN: Controlled laboratory study. METHODS: In 8 fresh-frozen cadaveric shoulders, the rotator cuff and overlying muscles were removed, and the glenohumeral capsule, coracoacromial ligament, and coracohumeral ligament were left intact. The scapula was fixed, and the humerus was placed in 90 degrees of shoulder abduction in a 6 degrees of freedom testing device. A compressive force of 44 N was applied. A thrower's shoulder model was created, and sequential conditions were examined: intact, after anterior stretching, and after the addition of posterior-inferior capsular plication. Kinematic measurements were obtained through a complete range of glenohumeral rotation. RESULTS: Glenohumeral external rotation increased 16%, from 149 degrees to 173 degrees (P < .001), after stretching in external rotation and remained increased by 11% to 166 degrees (P < .001) after posterior-inferior capsular plication. With the addition of the posterior-inferior capsular plication, internal rotation averaged 7 degrees , which was not significantly different from the intact state (11 degrees, P = .55) or the stretched state (16 degrees, P = .07). The total glenohumeral rotation after stretching followed by posterior-inferior capsular plication did not differ significantly from intact state (P = .25). At maximum external rotation, the humeral head apex was shifted posteriorly in the stretched (P = .003) and plicated (P < .001) states compared with the intact state. The humeral head apex was posteriorly displaced at 135 degrees and 150 degrees of external rotation compared with the intact condition (P = .039 and .049, respectively). In maximum internal rotation, anterior stretching had no significant effect on the humeral head apex position. However, after posterior-inferior capsular plication, the humeral head apex was significantly shifted inferiorly (P = .005) and anteriorly (P = .03) in maximum internal rotation compared with the intact state. CONCLUSION: Significant changes in glenohumeral motion occur in this model during the simulated late-cocking and follow-through phases of throwing. In this model, posterior capsular tightness alters the humeral head position most profoundly during the deceleration and follow-through phases of throwing.

Aged↗
PubMed1997

The direction of celestial rotation influences the development of stellar orientation in young garden warblers (Sylvia borin)

The study presented here was conducted in order to analyze the role of the direction of celestial rotation in the development of stellar orientation in young migratory birds. The test birds were garden warblers, Sylvla borin, which leave their breeding ground on a southwesterly compass course. The birds were hand-raised and, during the premigratory period, exposed to an artificial 'sky' in the local geomagnetic field. For the control group C, the star pattern was rotating in the natural direction, with the centre of rotation and magnetic North coinciding. For the three experimental groups, the star pattern was rotating in the opposite direction; for group E1, the centre of rotation coincided with magnetic North, for group E2 the centre of rotation was at magnetic West and for group E3 it was at magnetic East. During autumn migration, the birds were tested without magnetic information under the same, now stationary, sky. All four groups were able to use stellar information for orientation, but only the control group preferred the normal southwesterly course. The three experimental groups, in contrast, all oriented towards a significantly different direction, preferring due south. The results for group E1 showed less scatter than those for the other two experimental groups. These results indicate that the direction of celestial rotation is crucial for the development of the normal migratory course with respect to the stars in young garden warblers. Establishing the species-specific southwesterly migratory course requires an interaction between celestial rotation and magnetic cues; this interaction appears to depend on the natural direction of celestial rotation. Rotation in the reverse direction allowed the birds to respond only in a manner that oriented them away from the centre of rotation.

Journal Article↗
PubMed2004

An eye movement analysis of "mental rotation" of simple scenes.

Participants saw a standard scene of three objects on a desktop and then judged whether a comparison scene was either the same, except for the viewpoint of the scene, or different, when one or more of the objects either exchanged places or were rotated around their center. As in Nakatani, Pollatsek, and Johnson (2002), judgment times were longer when the rotation angles of the comparison scene increased, and the size of the rotation effect varied for different axes and was larger for same judgments than for different judgments. A second experiment, which included trials without the desktop, indicated that removing the desktop frame of reference mainly affected the y-axis rotation conditions (the axis going vertically through the desktop plane). In addition, eye movement analyses indicated that the process was far more than a simple analogue rotation of the standard scene. The total response latency was divided into three components: the initial eye movement latency, the first-pass time, and the second-pass time. The only indication of a rotation effect in the time to execute the first two components was for z-axis (plane of sight) rotations. Thus, for x- and y-axis rotations, rotation effects occurred only in the probability of there being a second pass and the time to execute it. The data are inconsistent either with an initial rotation of the memory representation of the standard scene to the orientation of the comparison scene or with a holistic alignment of the comparison scene prior to comparing it with the memory representation of the standard scene. Indeed, the eye movement analysis suggests that little of the increased response time for rotated comparison scenes is due to something like a time-consuming analogue process but is, instead, due to more comparisons on individual objects being made (possibly more double checking).

Concept Formation↗
PubMed2002

Measuring the axial rotation of lumbar vertebrae in vivo with MR imaging.

BACKGROUND AND PURPOSE: Flexion-extension radiography is neither sensitive nor specific in the diagnosis of degenerative spinal instability, a presumed cause of back pain and an indication for spinal fusion. We tested the hypothesis that with MR imaging and a device to rotate the torso, axial rotations of lumbar vertebrae can be measured with sufficient accuracy and that significantly different rotations can be detected between lumbar segments with degenerated disks and those with normal disks. METHODS: We studied five volunteers without back pain (group 1), five patients who underwent MR imaging because of back pain but were not considered candidates for fusion (group 2), and five patients in whom diskography identified one or more disks with concordant pain (group 3). Each participant was placed on a specially built table that provided separate supports for the torso and for the hips and legs. Series of sagittal images were acquired with a T2-weighted fast spin-echo sequence, with the torso rotated clockwise and then counterclockwise. The amount of rotation was calculated from axial images with use of an automated program. RESULTS: In the five volunteers, rotations of the lumbar motion segments varied between -1.8 degrees and 5.7 degrees, with an average of 0.8 degrees. The abnormal disks in five patients in group 2 rotated from -0.9 degrees to 5.6 degrees, with an average of 3.2 degrees. In group 3, the disks in which concordant pain was elicited rotated from 0.8 degrees to 4.4 degrees, with an average of 2.2 degrees. Difference in rotation between abnormal and normal disks was statistically significant. CONCLUSION: Measurements of rotations of lumbar vertebrae with MR imaging may have value for determining levels that move abnormally in axial rotation.

Adult↗