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At least 649 records · Page 36Linked to original sources
PubMed1999

Maximum internal carotid arterial stenosis: assessment with rotational angiography versus conventional intraarterial digital subtraction angiography.

PURPOSE: To assess how often rotational angiography depicts more severe internal carotid arterial stenosis compared with conventional intraarterial digital subtraction angiography (DSA) in two or three projections and how frequently this factor may affect patient treatment. MATERIALS AND METHODS: Rotational angiography (16 or 32 projections) was performed in addition to DSA in 47 stenotic internal carotid arteries (ICAs) in 38 symptomatic patients. ICA stenosis was measured independently at DSA and at rotational angiography with North American Symptomatic Carotid Endarterectomy Trial criteria. The degree of stenosis was categorized as 0%-29%, 30%-49%, 50%-69%, or 70%-99%. RESULTS: In three ICAs, rotational angiography was nondiagnostic. In 28 of the remaining 44 ICAs, the degree of stenosis was categorized similarly with DSA and rotational angiography, whereas with rotational angiography, 15 ICAs were classified one category higher and one ICA was classified two categories higher, owing to the increased number of projections available. Seventy percent to 99% stenosis was demonstrated in 18 ICAs with DSA and in 25 ICAs with rotational angiography. Thus, rotational angiography could have facilitated a change in the optimal treatment (from nonsurgical treatment to carotid arterial endarterectomy) in seven ICAs. CONCLUSION: Compared with DSA in two or three projections, rotational angiography frequently depicts more severe ICA stenosis. This indicates a limitation of DSA in depicting the maximum ICA stenosis.

Aged↗
PubMed2006

Rotation of motoneurons during prolonged isometric contractions in humans.

Prolonged and weak isometric contractions can result in neuromuscular fatigue. Alternation of discharge of motor units with similar thresholds (termed rotation) could be useful to minimize neuromuscular fatigue by providing periods for metabolic recovery of the contractile elements. In the present study, we investigated the prevalence of motoneuron rotation during prolonged contractions of distal limb muscles. Electromyographic (EMG; needle and surface) was recorded from muscles of the forearm and distal leg. The subject made a slowly increasing isometric contraction to recruit and discharge a motor unit (1) for a prolonged period of time (> 30 min). Sometimes an additional motor unit (2) was recruited in which case the subject relaxed the contraction slightly so that only one motor unit remained tonic. Often it was this newly recruited motor unit (i.e., unit 2) that continued discharging, while motor unit 1 fell silent. Continued contraction would then lead to the resumption of tonic discharge of unit 1 and silence of unit 2. This would complete a rotation between motor units 1 and 2. During prolonged contractions, rotation was observed in approximately 80% of the motor-unit pairs examined. There was no difference in rotation incidence by muscle type. For the unit pairs showing rotation, surface EMG values were significantly higher immediately prior to rotation than after rotation had occurred. Our findings show that rotation of motor units with similar recruitment thresholds during such contractions is common in distal muscles of the arm and leg and may help offset neuromuscular fatigue.

Adult↗
PubMed2003

Precise oculomotor correlates of visuospatial mental rotation and circular motion imagery.

Visual imagery is a basic form of cognition central to activities such as problem solving or creative thinking. Phenomena such as mental rotation, in which mental images undergo spatial transformations, and motion imagery, in which we imagine objects in motion, are very elusive. For example, although several aspects of visual imagery and mental rotation have been reconstructed through mental chronometry, their instantaneous evolution has never been directly observed. We paired mental chronometry to eye movement recording in subjects performing a visuospatial mental rotation task and an instructed circular motion imagery task. In both tasks, sequences of spontaneous saccades formed curved trajectories with a regular spatio-temporal evolution. In the visuospatial mental rotation task, saccadic amplitude decreased progressively within each sequence, resulting in an average gaze rotation with a bell-shaped asymmetrical angular velocity profile whose peak and mean increased with the amount of the to-be-performed rotation, as in reaching movements. In the second task, the average gaze rotation reproduced faithfully the to-be-imagined constant-velocity circular motion, thus excluding important distortions in the oculomotor performance. These findings show for the first time the instantaneous spatio-temporal evolution of mental rotation and motion imagery. Moreover, the fact that visuospatial mental rotation is modeled as a reaching act suggests that reaching pertains to the realm of visuospatial thinking, rather than being restricted to the motor domain. This approach based on eye movement recording can be profitably coupled to methods such as event-related potentials, transcranial magnetic stimulation, or functional magnetic resonance to study the precise neuronal dynamics associated with an ongoing mental activity.

Adult↗
PubMed2002

Influence of the clinical rotation on intern attitudes toward pediatrics.

Knowledge of graduate student's impressions and attitudes toward pediatrics is important for planning strategies to stimulate their interest in pursuing a career in pediatrics. The clinical pediatric experience may influence many of their misconceptions and apprehension. This study was designed to examine this hypothesis. Rotating interns who were starting pediatric rotations between January 8, 1998 and January 4, 2001 were included prospectively. A structured 2-part, 28-item questionnaire examining their impressions and attitudes toward pediatrics was completed on the first week and at the end of the 8-week rotation. One hundred eighty-eight interns (53.5% males) aged 23 to 30 years (mean 24.8, SD 1.3) were included. One hundred two pre- and 86 post-rotation questionnaires were completed. Selecting pediatrics as the first future career choice did not change significantly at the end of the rotation, from 19.5% to 26% post-rotation. Females were 3.4 times more likely to select pediatrics (95% CI 1.6-7.8, p = 0.001). Several impressions about the specialty were significantly changed at the end of the rotation including worry about inflicting pain (28% vs 12%, p = 0.01), concerns about difficulties in the examination and cooperation of children (22% vs 8%, p = 0.01), and difficulties with intravenous access (43% vs 17%, p = 0.0003). Most interns (76%) felt that their pediatric rotation was better than anticipated. To conclude, although the rotation experience did not increase the likelihood of selecting pediatrics as the first future career choice, many impressions and concerns were positively influenced. The majority reported a better than anticipated experience.

Adult↗
PubMed2006

Using resident input to identify and integrate essential components of a foot and ankle rotation.

BACKGROUND: Foot and ankle surgery is one of the orthopaedic subspecialties to which residents not uncommonly receive limited exposure. Therefore, it is important to identify what both faculty and residents regard as fundamental to a foot and ankle rotation. The purposes of this study were to identify the essential components of a foot and ankle rotation and to correlate these with the American Orthopaedic Foot and Society (AOFAS) core curriculum, and to discuss how to integrate resident input and AOFAS guidelines into a valued foot and ankle rotation. METHODS: Over a 5-year period, each orthopaedic resident beginning a 10-week postgraduate year (PGY) 3 foot and ankle rotation was asked to choose topics to be covered during weekly 45-minute discussion conferences. Each resident also identified personal goals for the rotation. Data were collected in this prospective nature, and the responses of the 24 PGY 3 residents from our program who completed the rotation between February, 2000, and April, 2005, were analyzed. The discussion conference topics were compared to the AOFAS guidelines, and the top 10 personal goals were determined. Prerotation and postrotation Orthopaedic Inservice Training Examination (OITE) foot and ankle scores for the residents also were analyzed. RESULTS: Among the nine AOFAS core curriculum categories, residents most frequently chose chronic soft-tissue foot and ankle problems, followed in frequency by foot and ankle arthritis, foot and ankle trauma, and diabetic foot. Individually, posterior tibial tendon insufficiency, hallux valgus, diabetic foot, and calcaneal fracture were the most frequently chosen discussion conference topics. In regards to personal goals for the rotation, residents most commonly wanted to improve their physical examination skills (88%) and increase their orthotic knowledge (71%). The OITE scores improved by a mean of 12% after the rotation. CONCLUSIONS: This study provides new and detailed information about resident expectations for a valued foot and ankle rotation. These results should be integrated with existing AOFAS guidelines to further refine the essential components of a core foot and ankle curriculum.

Ankle↗
PubMed2004

A session of multiple choice questions in the orientation process to the adolescent medicine rotation.

BACKGROUND: Although adolescent health care training curricula for resident physicians have been developed during the past 2 decades, little is known about the orientation process to the adolescent medicine rotation. DESCRIPTION: Since 1996, we have incorporated a session consisting of 40 multiple-choice questions (MCQ) in the orientation process to our hospital-based adolescent medicine rotation. In this study, we evaluated residents' opinions about the MCQ format. EVALUATION: An anonymous questionnaire was distributed in 2002 to 123 resident physicians who had gone through an adolescent medicine rotation between 1996 and 2002. A total of 68 physicians responded (55% response rate). Almost all respondents (99%) stated that the MCQ session was a good format to use during orientation to adolescent medicine. Most (85%) said that it previewed issues that they had to face during the rotation, 74% said that it allowed them to think about issues in adolescent medicine, and 65% said that it directed them to subjects they needed to read about for this rotation. About 45% of respondents stated that the MCQ session increased their level of comfort with seeing adolescent patients on the first few days of the rotation. The majority of respondents (71%) stated that an attending needed to personally review the answers with the residents. Of these, all said that the attending could expand and explore the issues, and 71% said that the attending could show locations and use of certain instruments (orchidometer, scoliometer, etc.) related to questions. Almost a fifth (18%) preferred to receive a printed answer sheet that they could review privately. Of these, 58% feared that review with an attending might prejudice the attending against them if they had errors, and 25% stated that it would be too stressful for them to have the attending check their answers on the 1st day of the rotation. Most respondents (87%) recommended that the MCQ format be used as part of the orientation process to other rotations as well. CONCLUSIONS: Resident physicians viewed the MCQ session as a good format to use in the orientation process to the adolescent medicine rotation. A review of the answers with an attending was preferred over receiving a printed answer sheet.

Adolescent↗
PubMed2005

Effect of crop rotation distance on populations of Colorado potato beetle (Coleoptera: Chrysomelidae): development of areawide Colorado potato beetle pest management strategies.

The Colorado potato beetle, Leptinotarsa decemlineata (Say), overwinters adjacent to field edges and infests nearby fields in the spring, primarily by walking. Crop rotation is known to be an effective cultural control against Colorado potato beetle populations limiting spring infestations. Spatial separation is an important consideration in optimizing the rotational effect because long-distance rotations have been shown to reduce Colorado potato beetle infestations. To determine the effect of long-distance rotations on Colorado potato beetle populations in commercial Wisconsin potato production, a geographic area of >18,200 ha (>45,000) acres in southern Portage County, Wisconsin, was selected as an experimental area for areawide pest management of the Colorado potato beetle. From 1997 to 1999, beetle populations at edges within each potato field in this region were determined by spring and fall field sampling. The rotational distance between current and previous potato fields was measured and analysis was run between the distance and Colorado potato beetle populations. Long-distance rotations of >400 m were an effective cultural control management strategy to limit adult beetle infestations in the spring. This strategy can be optimized when collaborating growers are able to maximize their rotational distances by coordinating their rotational schemes within large areawide, geographic locations. Deploying long-distance rotations within a geographic area over many years would limit Colorado potato beetle populations and could result in a significantly reduced Colorado potato beetle populations entering fields in the spring.

Agriculture↗
PubMed2006

Point-source irradiation with eccentric rotation causes inhomogeneous dose distribution.

Radioactive point sources are regularly used for irradiating cell culture and other biological materials. Eccentric rotation is often used to minimize dose disparities that arise from irradiating samples that span a distance from the point source. Rotation provides a great improvement in dose homogeneity compared to inert irradiation yet still presents an obvious shortcoming for exposures in which the sample completes only partial rotation or fractional rotation. In such cases, certain areas of the sample have a closer average distance to the radiation source than other areas within the same sample. This obstacle can be partially overcome by adjusting rotation speed so the sample traverses a full rotation (or multiple thereof) throughout the total irradiation time. Here we investigate the effects of irradiation with eccentric rotation on dose homogeneity. We show that due to the inverse square law that governs dose, even exposures with full rotation result in inhomogeneous dose distributions. This dose inhomogeneity can be substantial, especially for large samples and small source- sample distances. We observed a 33% difference in survival across 100-mm dishes and a 400% difference for 150-mm dishes. The dose inhomogeneity inherent to eccentric rotation increases the actual average dose delivered across the sample compared to that delivered at sample center. We offer a table of correction factors that account for this dose increase and correct the dose delivered at center to the actual average dose delivered across the entire sample.

Animals↗
PubMed2005

Effects of elbow flexion and forearm rotation on valgus laxity of the elbow.

BACKGROUND: Clinical evaluation of valgus elbow laxity is difficult. The optimum position of elbow flexion and forearm rotation with which to identify valgus laxity in a patient with an injury of the ulnar collateral ligament of the elbow has not been determined. The purpose of the present study was to determine the effect of forearm rotation and elbow flexion on valgus elbow laxity. METHODS: Twelve intact cadaveric upper extremities were studied with a custom elbow-testing device. Laxity was measured with the forearm in pronation, supination, and neutral rotation at 30 degrees, 50 degrees, and 70 degrees of elbow flexion with use of 2 Nm of valgus torque. Testing was conducted with the ulnar collateral ligament intact, with the joint vented, after cutting of the anterior half (six specimens) or posterior half (six specimens) of the anterior oblique ligament of the ulnar collateral ligament, and after complete sectioning of the anterior oblique ligament. Laxity was measured in degrees of valgus angulation in different positions of elbow flexion and forearm rotation. RESULTS: There were no significant differences in valgus laxity with respect to elbow flexion within each condition. Overall, for both groups of specimens (i.e., specimens in which the anterior or posterior half of the anterior oblique ligament was cut), neutral forearm rotation resulted in greater valgus laxity than pronation or supination did (p < 0.05). Transection of the anterior half of the anterior oblique ligament did not significantly increase valgus laxity; however, transection of the posterior half resulted in increased valgus laxity in some positions. Full transection of the anterior oblique ligament significantly increased valgus laxity in all positions (p < 0.05). CONCLUSIONS: The results of this in vitro cadaveric study demonstrated that forearm rotation had a significant effect on varus-valgus laxity. Laxity was always greatest in neutral forearm rotation throughout the ranges of elbow flexion and the various surgical conditions. CLINICAL RELEVANCE: The information obtained from the present study suggests that forearm rotation affects varus-valgus elbow laxity. Additional investigation is warranted to determine if forearm rotation should be considered in the evaluation and treatment of ulnar collateral ligament injuries of the elbow joint.

Aged↗
PubMed1989

Haptic identification of rotated letters using the left or right hand.

The present study investigated the effects of the use of the left and right hands on haptic identification of letters which were presented in either a normal (0 degrees rotation), downward (90 degrees clockwise rotation), upside down (180 degrees rotation), or facing upward (270 degrees rotation) position. Each of the 80 right-handed subjects was given five series of randomly ordered presentations of sets of 8 letters of the alphabet. The subjects were asked to feel and then name each letter correctly as quickly but as accurately as possible. Times showed no effect of hand, but significant effects were found for different sets of letters, degree of rotation and a significant decrease in identification time was observed across the five series. Interactions occurred between hand and rotation as well as set and rotation. Errors showed a significant interaction of hand with degree of rotation; the right was superior at 0 degrees but the left was superior at 90 degrees. The results were discussed in terms of hypotheses of hemisphere function, mental rotation, and stimulus familiarity.

Adolescent↗
PubMed1984

Grading and rotational crossbreeding of beef cattle. I. Reproductive performance.

Purebred Angus (A), Polled Hereford (PH) and Santa Gertrudis (SG) bulls were mated to grades, two-breed and three-breed rotational crosses of these breeds (seven herds) to produce three generations (G1, G2 and G3) of calves. The grade A and PH cows were higher in A and PH breeding, respectively, than grade SG cows were in SG breeding. Reproductive performance among grade and rotational-cross herds was evaluated for herd differences, heterosis and effects of various genetic components. For cows that produced G1 calves, the proportion of cows that calved, had a live calf and weaned a calf was higher (P less than .01) for those that calved compared with those that failed to calve the previous year. For cows that produced G2 and G3 calves, previous year's calving status did not affect (P greater than .05) reproductive performance. Grade A and PH were similar (P greater than .05) in reproductive performance during G1, G2 and G3. As generations advanced, SG decreased in reproductive performance. Except for the PH-SG rotational cross in G3, the A, PH and all two-breed rotational crosses and the three-breed rotational cross generally were similar (P greater than .05) for the three reproductive traits during each generation. Within generations, reproductive performance was similar (P greater than .05) between rotations within each of the two-breed rotational cross herds. For the three-breed rotational cross herd, differences due to rotation generally were not significant during G1 and G2, but for G3, the SG sires were associated with lower (P less than .05) reproductive performance for each of the three reproductive traits compared with A and PH sires. Heterosis percentages generally were positive but not significant for each of the three reproductive traits. On the basis of additive and maternal effects of A and SG expressed as deviations from PH, the only genetic component that significantly affected reproductive performance was the detrimental additive effect of SG in G2 and G3 for each of the three reproductive traits. Also, there was a consistent negative relationship between breed additive and maternal components for each of the three reproductive traits during each generation. Only 4 to 7% of the variation in reproductive performance was accounted for in the analyses that included breed additive, breed maternal, heterosis and average maternal heterosis effects. Averaged over generations, from .1 to .4% additional variation was due to factors that may have included specific maternal heterosis, epistasis and linkage.

Animals↗
PubMed2001

Comparing viewer and array mental rotations in different planes.

Participants imagined rotating either themselves or an array of objects that surrounded them. Their task was to report on the egocentric position of an item in the array following the imagined rotation. The dependent measures were response latency and number of errors committed. Past research has shown that self-rotation is easier than array rotation. However, we found that imagined egocentric rotations were as difficult to imagine as rotations of the environment when people performed imagined rotations in the midsagittal or coronal plane. The advantages of imagined self-rotations are specific to mental rotations performed in the transverse plane.

Adult↗
PubMed1991

Perception of three-dimensional angular rotation.

In three experiments, difference thresholds (dLs) and points of subjective equality (PSEs) for three-dimensional (3-D) rotation simulations were examined. In the first experiment, observers compared pairs of simulated spheres that rotated in polar projection and that differed in their structure (points plotted in the volume vs. on the surface), axis of rotation (vertical, y, vs. horizontal, x), and magnitude of rotation (20 degrees-70 degrees). DLs were lowest (7%) when points were on the surface and when at least one sphere rotated around the y-axis and varied with changes in the independent variables. PSEs were closest to objective equality when points were on the surface of both spheres and when both spheres rotated about the x-axis. In the second experiment, subjects provided direct estimates of the rotations of the same spheres. Results suggested a reasonable agreement between PSEs for the indirect-scaling and direct-estimate procedures. The third experiment varied sphere diameter (and therefore mean linear velocity of stimulus elements) and showed that although rotation judgments are biased by mean linear velocity, they are not likely to be made solely on the basis of that information. These and past results suggest a model whereby recovery of structure is conducted by low-level motion-detecting mechanisms, whereas rotation (and other) judgments are based on a higher level representation.

Acceleration↗
PubMed1993

The frame turns also: factors in differential rotation in pictures.

When pictures of simple shapes (square, diamond) were seen frontally and obliquely, (1) the shapes with a deeper extent into pictured space underwent more rotation (Goldstein, 1979), which is an apparent turning to keep an orientation toward an observer's changing position; (2) there was little effect of whether the observer knew the picture surface's orientation in real space, except that such knowledge could prevent multistability; and (3) depicted picture frames also rotated. In other experiments, figural and frame rotations were independent of each other, and rotation was shown for real frames. The rotation of depthless depictions suggests that at least two rotational factors exist, one that involves the object's virtual depth and one that does not. The nature of this second factor is discussed. Frame rotation appeared to subtract from object rotation when the two were being compared; this could explain a paradox in picture perception: Depicted orientations often seem little changed over viewpoints, despite (apparent) rotations with respect to real-space coordinates.

Adult↗
PubMed2000

Differential effects of permanent and rotating shifts on self-report sleep length: a meta-analytic review.

STUDY OBJECTIVES: The current study used the meta-analytic technique to quantitatively assess the effects of permanent and rotating shift-work schedules on sleep length. DESIGN: A meta-analysis was completed on 36 primary studies resulting in 165 effect sizes. Effect sizes comparing shift-workers to a permanent day shift control group were calculated for permanent evening shifts, permanent night shifts, and morning, evening, and night shifts worked as part of slowly and rapidly rotating shift systems. SETTING: NA PATIENTS OR PARTICIPANTS: NA INTERVENTIONS: NA RESULTS: Permanent night shifts resulted in a decrease, whereas permanent evening shifts resulted in an increase in sleep length. The shifts within rotating schedules followed the same pattern, with the addition of morning shifts having a moderate detrimental effect on sleep length. Furthermore, the speed of shift rotation had an impact. Slowly rotating shifts, in general, had the least detrimental effect on sleep length of the permanent and rotating shift-work schedules studied here. The pattern of effects among morning, evening, and night shifts was the same for rapidly and slowly rotating shifts, with night shifts having the greatest detrimental effect, morning shifts having a moderate detrimental effect and evening shifts having a positive effect on sleep length. In addition, nights on rotating shifts had a greater negative effect on sleep length than permanent night shifts. CONCLUSIONS: Slowly rotating shifts have the least negative impact on sleep length of shift-work schedules including a night shift. However, permanent night shifts could be an alternative shift-work schedule in operational settings that require many workers at night.

Circadian Rhythm↗
PubMed2001

Evaluation of high-resolution pinhole SPECT using a small rotating animal.

UNLABELLED: Ex vivo measurements in animals are used frequently in the field of nuclear medicine for the characterization of newly developed radioligands and for drug development. In vivo SPECT would replace these ex vivo measurements in a relatively large number of cases if one were able to adequately image small organs. The pinhole collimator has been used extensively to obtain greater detail in planar imaging. However, using a pinhole collimator for SPECT is difficult because it requires a heavy collimated detector to rotate around a small object with a constant radius of rotation. METHODS: We have developed a mechanism in which the gantry and collimator are fixed and the animal rotates. Hollow cylinders of different sizes were made to enable imaging of small animals of different sizes: mice, hamsters, and rats. The cylinder is mounted on a stepping motor-driven system and positioned exactly above the pinhole collimator of an ARC3000 camera with a 1-mm pinhole insert. The stepping motor is controlled by the Hermes acquisition/processing system. After imaging each projection, a signal is given to rotate the stepping motor with the desired number of angular degrees. Filtered backprojection, adapted to pinhole SPECT, was used for reconstruction. The system allows adjustments of the radius of rotation and along the axis of the cylinder to select the field of view. Calibration experiments were performed to ensure that the axis of rotation was exactly in the middle of the cylinder. Phantom experiments were performed to assess sensitivity, spatial resolution, and uniformity of the system and to test the system for distortion artifacts. In addition, a brain dopamine transporter rat study and a hamster myocardial study were performed to test the clinical feasibility of the entire system. RESULTS: In the line source experiment, the spatial resolution obtained in air was 1.3 mm full width at half maximum, with a radius of rotation of 33 mm. Furthermore, the system has good uniformity and is capable of detecting cold spots of 2-mm diameter. The animal studies showed that it was feasible to image receptors or transporters and organs with sufficient detail in a practical setup. CONCLUSION: A rotating cylinder mechanism for pinhole SPECT is feasible and shows the same characteristics as conventional pinhole SPECT with a rotating camera head, without distortion artifacts. This mechanism permits pinhole SPECT to replace many ex vivo animal experiments.

3-Iodobenzylguanidine↗
PubMed2005

Do benefits accrue from longer rotations for students in Rural Clinical Schools?

INTRODUCTION: The Australian Government has provided funding for Rural Clinical Schools (RCS) to provide substantial rural clinical experience to medical students. The strategy aims to acculturate students into rural living with the intended long-term outcome of increasing the availability and viability of rural health services. When evaluators from two of the Rural Clinical Schools discussed findings and insights relating to rural rotations from their in-depth evaluation studies of their respective schools they found a range of similarities. This article is a collaboration that articulates parallel findings from evaluations over 2 years, using three different approaches to students' placements across the two RCS: (1) students based long term in one centre (with only a few days away at a time); (2) students based long term in one centre with short-term rotations of 3-6 weeks away from home base; and (3) week rotations without a home base. METHOD: The two RCS, as part of their initial establishment, put comprehensive internal evaluation processes in place, including the employment of dedicated evaluators extant from the teaching and assessment of the rural medical curriculum. Data were collected and analysed according to standard education evaluation procedures. RESULTS: Home-base preference: most students preferred having a home base in one centre and having as little time as possible away from that centre, while recognising that sometimes the requirement to go and learn elsewhere was useful. The reasons for this were three-fold: academic, clinical and social. Academic benefits: students enjoyed the excellence of teaching and learning opportunities in their rural sites and did not want their discipline of learning interrupted by what they perceived as unnecessary change. Students with a home base used their learning opportunities qualitatively differently from those students who had 6 week rotations. Their learning became self-directed and students sought opportunities to extend and consolidate areas of need. Clinical benefits: contributions to the clinical team: students in their clinical years want to feel useful and to be allowed to become contributors to the medical care, even as they are learning. A longer rotation allows them to become known to their teachers who are then able to easily assess the type of contribution that is appropriate for their students to undertake. Students then become full participating members of the healthcare team, rather than observing learners. Social benefits: all students with a home base actively participated in a wide range of community activities outside their role as medical students. Those students undertaking short rotations without a home base seldom connected in the same way to any rural community. CONCLUSION: Evaluation from these two RCS has shown that short rotations are likely to be less optimal than longer rotations for meeting the broader goals of the RCS to build future workforce capacity. Our results suggest that one opportunity to acculturate students into the rural lifestyle is lost when students' placements are insufficiently long for them to put down roots in their community, and to understand how to 'live' there more broadly. Good rural experiences and teaching and learning opportunities are not sufficient in themselves. Students' emotional attachment to rural living comes from experience related to time and the connection to local people that comes as a result of time spent in the community. Students on short rotations do not make that local connection.

Australia↗
PubMed1992

[Discrimination learning of rotated faces: a Markov analysis of coding and association processes].

30 subjects participated in a discrimination experiment learning face-letter associations under four rotation conditions (45 degrees, 90 degrees, 135 degrees, 180 degrees). Under each condition two thirds of the faces were presented twice, upright and rotated away from the vertical; the remaining faces were presented once, upright or rotated. Learning is described by a joint Markov model: For faces that are presented twice it assumes a separate association and encoding process (two-stage-model), for faces that are presented once it assumes an association process (all-or-none-model). The Markov model fits the data for all four rotation conditions. The angle of rotation does not affect learning for faces that are presented once. For faces that are presented twice it influences both the association and the encoding process. For the angles employed, the effect of rotation can be approximated linearly. The results suggest that the encoding of a rotated face differs increasingly from an upright face as a function of these angles of rotation. This confirms analogous conclusions from mental rotation experiments.

Adult↗