Total Rotation Research Articles

Sub-assemblage low damage connection incorporating blind-bolts and RBRFs subjected to cyclic loading

The Christchurch earthquake has given a renewed impetus to the development and use of low damage connections within moment-resisting frames in New Zealand. When using a low-damage technology, the building is designed to be easily repairable after a severe earthquake and is hence expected to be more resilient and cost-effective. This paper reports on a sub-assemblage test that investigates the behaviour of a newly proposed low damage connection between a steel beam and composite column. The connection incorporates blind-bolts, curved T-stubs and replaceable buckling restrained fuses (RBRFs). The RBRF is the only element which is allowed to yield when the earthquake level is higher than the design-based earthquake, so the establishment of a suitable strength hierarchy is vital to the success of the design. Two loading protocols have been applied using the same sub-assemblage but with a new RBRF at the start of each test; i.e. the RBRF was replaced after each test. The contributions of the connection, beam, and column to the total rotation have been summarised. The results show that a semi-rigid connection can be achieved by using this type of connection. Furthermore, an analytical approach has been proposed to predict the behaviour of this type of connection.

Biomechanical Analysis of Single-, Double-, and Triple-Bundle Configurations for Coracoclavicular Ligament Reconstruction Using Cortical Fixation Buttons With Suture Tapes: A Cadaveric Study

To compare the acromioclavicular (AC) joint stability of single-bundle (SB), double-bundle with an anterolateral limb (DBa), double-bundle with a posterolateral limb (DBp), and triple-bundle (TB) coracoclavicular (CC) ligament reconstructions using cortical fixation buttons with suture tapes. Eight cadaveric shoulders were used. AC joint translation and rotational stability were tested for intact and following 4 different CC reconstruction techniques: SB, DBa, DBp, and TB configurations using cortical fixation buttons with suture tapes. For each reconstruction and native AC joint as control, anteroposterior (AP) and superoinferior translations were quantified using 10- and 15-N translational loadsand anterior and posterior rotations were measured using 0.16- and 0.32-Nm rotational torque. DBp reconstruction showed significantly better AP stability compared with SB and DBa reconstruction at 10 and 15N (DBp: 4.1 ± 0.6mm, SB: 7.8 ± 1.1mm, P < .001; DBa: 6.5 ± 0.7mm, P= .02 at 10N; DBp: 5.5 ± 0.8mm, SB: 10.1 ± 1.0mm, P=.003; DBa: 9.1 ± 0.7mm, P= .02 at 15N). The degree of total rotation showed tendency to decrease according to increasing number of bundles; however, there were no significant differences (SB: 43.1 ± 9.2°, DBa: 37.9 ± 7.3°, DBp: 33.9 ± 6.8°, TB: 32.2 ± 6.6°, P= .37 at 0.32 Nm). An additional posterolateral clavicular hole for CC ligament reconstruction using cortical fixation buttons with suture tapes resulted in better AP stability compared with SB reconstruction, whereas use of additional anterolateral clavicular hole did not show any improvement compared with SB reconstruction. Reconstruction using both anterolateral and posterolateral clavicular holes did not guarantee better stability compared with SB reconstruction. There was an increasing tendency of rotational stability with number of bundle increases, although they did not reach statistical difference. When surgeons consider double-bundle CC ligament reconstruction using cortical fixation buttons with suture tapes, it is better to position the lateral clavicular hole posteriorly to restore AP stability.

Factors influencing outcomes of nonsurgical treatment for baseball players with SLAP lesion

Background/objectiveSuperior labrum anterior posterior (SLAP) lesion of the shoulder joint occurs in throwing athletes as a results of overuse, such as from repetitive baseball pitching. Nonsurgical treatments are usually the first-line therapy for symptomatic SLAP lesion. However, some patients cannot obtain satisfactory improvement of their symptoms, leading to dysfunction of the shoulder and diminished pitching performance. The purpose of this study was to analyze factors that influence outcomes of nonsurgical treatments for SLAP lesion. MethodsForty-five baseball players with SLAP lesion, whose mean age was 21.6 (range, 16–36) years and who underwent nonsurgical treatments, were the subjects of this study. SLAP lesion was diagnosed by shoulder arthrography and magnetic resonance imaging (MRI). Exclusion criteria included definite associated trauma such as dislocation, fracture or injuries related to sports activities. Playing positions included pitcher (21 patients), catcher (3 patients), infielder (13 patients) and outfielder (8 patients). Mean symptomatic duration from the onset of shoulder pain to the beginning of nonsurgical treatments was 8.5 (range, 1–72) months. Nonsurgical treatments included physical therapy, such as range of motion, stretching, and rotator cuff exercises, as well as prescription of nonsteroidal anti-inflammatory drugs if necessary. To identify factors that influenced outcomes of nonsurgical treatments for SLAP lesion, various factors of 13 nonresponsive patients were compared with those of 32 patients who responded to nonsurgical treatment. The factors were as follows: patient background, such as age or playing position; range of shoulder motion; shoulder joint laxity; and findings of radiographs and MRI. All data were statistically assessed using logistic analysis and Spearman's correlation coefficient. The significance level was set at P < 0.05, and odds ratios were determined. ResultsFactors identified as having significant difference between the 2 groups were age, duration of baseball experience, symptomatic period, playing position, range of internal and external rotation in the first medical examination, range of total rotation of 90° abduction 2 months after nonsurgical treatments, and presence of Bennett spur and partial-thickness tears of the articular-side rotator cuff. Factors with high odds ratios were symptomatic period, range of total rotation of 90° abduction 2 months after the treatment, age, and duration of baseball experience. ConclusionSymptomatic period, duration of baseball experience, age, and findings of radiographs and MRI are inevitable factors that cannot be improved by nonsurgical treatment. On the other hand, restriction of shoulder motion due to posterior muscular tightness is a factor that can be improved by nonsurgical treatment. Early improvement of shoulder motion is important to obtain satisfactory outcomes of nonsurgical treatments for SLAP lesion.

Between-session reliability of opto-electronic motion capture in measuring sagittal posture and 3-D ranges of motion of the thoracolumbar spine

This study evaluated between-session reliability of opto-electronic motion capture to measure trunk posture and three-dimensional ranges of motion (ROM). Nineteen healthy participants aged 24–74 years underwent spine curvature, pelvic tilt and trunk ROM measurements on two separate occasions. Rigid four-marker clusters were attached to the skin overlying seven spinous processes, plus single markers on pelvis landmarks. Rigid body rotations of spine marker clusters were calculated to determine neutral posture and ROM in flexion, extension, total lateral bending (left-right) and total axial rotation (left-right). Segmental spine ROM values were in line with previous reports using opto-electronic motion capture. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were calculated as measures of between-session reliability and measurement error, respectively. Retroreflective markers showed fair to excellent between-session reliability to measure thoracic kyphosis, lumbar lordosis, and pelvic tilt (ICC = 0.82, 0.63, and 0.54, respectively). Thoracic and lumbar segments showed highest reliabilities in total axial rotation (ICC = 0.78) and flexion-extension (ICC = 0.77–0.79) ROM, respectively. Pelvic segment showed highest ICC values in flexion (ICC = 0.78) and total axial rotation (ICC = 0.81) trials. Furthermore, it was estimated that four or fewer repeated trials would provide good reliability for key ROM outcomes, including lumbar flexion, thoracic and lumbar lateral bending, and thoracic axial rotation. This demonstration of reliability is a necessary precursor to quantifying spine kinematics in clinical studies, including assessing changes due to clinical treatment or disease progression.

Toward standardized patient positioning to avoid peripheral nerve injury during laparoscopic colorectal surgery: Application of a protocol and study of the resulting relationship between total rotation time and contact pressure at the shoulder.

Generally, laparoscopic colorectal surgery is performed with the patient in the lithotomy and rotated positions. The lithotomy position, however, is associated with intraoperative peripheral nerve injury (IPNI). We studied the relationship between patient positioning during laparoscopic colorectal surgery, contact pressure at the shoulder, and the occurrence of IPNI and tested a positioning protocol aimed at surgical safety in addition to maintenance of a good surgical field. We applied our positioning protocol in 44 cases and collected data that could be used to answer our study questions. We set limits for shoulder contact pressure and time in the rotation position. When the time limit was reached, we returned the patient to the supine position for 5 min. Patients' median age was 71 years; mean BMI was 22.4 kg/m2 . Median time in the rotation position was 126 min. For the 22 patients for whom validated data was obtained, mean lower shoulder pressure changed from 8.5 mmHg just after rotation to 11.4 mmHg 120 min after rotation (P = 0.013). Absence of IPNI in our patients confirmed the proposed relation between patient positioning and IPNI. Our data indicate that a prolonged period in the rotation position increases contact pressure at the shoulder, which can increase the risk of IPNI. Our patient positioning protocol appears to have prevented laparoscopic colectomy-related IPNI. Future studies are warranted to confirm the relationship between patient positioning and IPNI and, if necessary, to further refine the protocol to ensure prevention of IPNI during laparoscopic colorectal surgery.

The immediate effects of serving on shoulder rotational range of motion in tennis players

ObjectiveThis study aimed to investigate the immediate effects of serving on shoulder rotational range of motion (ROM) in tennis players by comparing to groundstrokes. DesignSame-subject, randomised, crossover study. SettingIndoor hard courts. ParticipantsEighteen male and 12 female professional and university level tennis players. Main outcome measuresPassive glenohumeral internal and external rotation ROM measurements, using a digital inclinometer, were undertaken at baseline and immediately following serving and groundstroke tasks on both dominant and non-dominant shoulders. Total rotation was calculated as the sum of internal and external rotation. ResultsOn the dominant and non-dominant shoulders there was no significant interaction effect between the factors of tennis task (serving and groundstrokes) and time (pre and post) (p = <0.05). Indicating that change in rotational ROM was not specific to tennis task. On the dominant shoulder there was a significant main effect of time (p = 0.007), with internal, external and total rotational ROM decreasing irrespective of tennis task. ConclusionBoth tennis tasks resulted in immediate significant reductions in shoulder rotational ROM on the dominant shoulder but not the non-dominant shoulder of professional and university tennis players. There was no significant difference between serving and groundstroke tasks.

Boosting an evolution strategy with a preprocessing step: application to group scheduling problem in directional sensor networks

This paper presents a two-membered evolution strategy based approach to address the total rotation minimization problem (TRMP) pertaining to directional sensor networks. TRMP is an $\mathcal {N}\mathcal {P}$ -hard problem. Performance of the proposed approach is enhanced by employing a pre-processing step that utilizes a constructive heuristic and the concept of opposite solutions. We have compared our approach with the best approach available in the literature. The experimental results demonstrate our approach to be highly effective with substantial gain in terms of solution quality, in comparison to the best approach available in the literature. However, our approach requires more time in comparison to this approach.

Efecto de la categoría de edad sobre el perfil de flexibilidad en jóvenes taekwondistas

El objetivo principal del presente estudio fue conocer el efecto de la categoría de edad sobre el perfil de flexibilidad en jóvenes taekwondistas usando pruebas angulares. Fueron reclutados un total de 17 taekwondistas jóvenes, que se clasificaron según su categoría federativa de edad en cadetes y junior. El rango de movimiento de los principales movimientos de la extremidad inferior fue valorado mediante el protocolo “ROM SPORT”. Se realizó un análisis descriptivo de cada una de las variables cuantitativas, que incluía la media y su correspondiente desviación típica. Una prueba t-test fue empleada para determinar la existencia de diferencias entre la extremidad dominante y no dominante. Además, la misma prueba estadística analizó la interacción entre los 11 movimientos seleccionados y las categorías de edad. Por último, se calculó el tamaño del efecto de los resultados. Los resultados mostraron diferencias significativas entre ambas categorías en EC (psoas-ilíaco), RIC (rotadores externos), REC (rotadores internos) y rotación total de la cadera (suma del RIC y REC). Estos resultados no coinciden con otros estudios que han valorado la flexibilidad en este mismo deporte. Los taekwondistas cadetes presentan valores de flexibilidad superiores a la categoría junior en los músculos rotadores internos y externo de cadera y en el psoas-iliaco.

Study of the Neutral Ekman Flow Using an Algebraic Reynolds Stress Model

A recently developed fully explicit algebraic model of Reynolds stress and turbulent heat flux in a thermally stratified planetary atmospheric boundary layer without stratification has been used for a numerical study of the Ekman turbulent boundary layer over a homogeneous rough surface for different dimensionless surface Rossby numbers. A comparative analysis has been conducted for a closure model of the transport term in the prognostic equation of turbulent kinetic energy dissipation including third-order moments. Dependences of the total wind rotation angle on the Rossby number have been obtained. The calculated vertical profiles of mean velocity, turbulent stress, turbulent kinetic energy, surface-friction velocity, and boundary-layer height agree satisfactorily with observational and earlier obtained LES data.

Intermittent Treadmill Running Induces Kinematic Compensations to Maintain Soccer Kick Foot Speed Despite No Change in Knee Extensor Strength.

Kicking is a fundamental skill and a primary noncontact mechanism of injury in soccer, with injury incidence increasing during the latter stages of match-play. Ten male professional soccer players completed a 90-minute treadmill protocol based on the velocity profile of soccer match-play. Preexercise, and at 15-minute intervals, players completed a maximal velocity kick subjected to kinematic analysis at 200Hz. Preexercise, and at the end of each half, players also completed isokinetic concentric knee extensor repetitions at 180°·s-1, 300°·s-1, and 60°·s-1. Kicking foot speed was maintained at ∼19m·s-1, with no main effect for exercise duration. In relation to proximal-distal sequencing during the kicking action, there was a significant increase in the duration (but not magnitude) of thigh rotation, with a compensatory decrease in the duration (but not magnitude) of shank rotation during the latter stages of the exercise protocol. In relation to long-axis rotation, pelvic orientation at ball contact was maintained at ∼6°, representing a total pelvic rotation in the order of ∼15° during the kicking action. Peak knee extensor torque at all speeds was also maintained throughout the protocol, such that kinematic modifications are not attributable to a decline in knee extensor strength.

Arthroscopic Superior Capsular Reconstruction in Males Provides Superior Outcomes to Reverse Total Shoulder or Debridement for Irreparable Rotator Cuff Tears

Objectives:Early results following arthroscopic superior capsular reconstruction(SCR) in patients with massive, irreparable rotator cuff tears are promising. However, no studies have compared patient reported outcomes between SCR or reverse total shoulder(rTSA) and rotator cuff debridement for these patients. Therefore, the purpose of this study was to compare 1-year outcomes between patients with massive irreparable rotator cuff tears who underwent a SCR, rTSA, or rotator cuff debridement with a concurrent biceps tenotomy or tenodesis.Methods:Patients(n=63) who underwent either SCR(n=21), rTSA(21), or cuff debridement(n=21) and biceps tenotomy or tenodesis for a massive, irreparable rotator cuff tear treated with a minimum 1-year follow up were retrospectively reviewed. Age, sex, BMI, smoking status, Charlson Index, Hamada classification, and ASES scores were recorded and compared using a multivariate ANOVA were used to compare between surgical approaches. A Chi Square analyses were used to compare sex distribution and the Charlson Deyo Index between groups (α=0.05).Results:Overall, patients across the 3 groups were not statistically different in age or follow up ASES score at minimum 14 month follow up (P> 0.05). There was a significant interaction effect between surgery group and sex (P=0.02) on ASES score but not age (P=0.08). Univariate F tests revealed that male patients who received an SCR displayed a 10-14% better outcome at follow up compared to other groups (Table 1) which exceeds the reported ASES score MCID.Conclusion:Our results show comparable results across surgical options for massive irreparable cuff tears with good patient reported outcomes. Male patients displayed clinically important greater ASES scores at 1 year follow up. Future studies should evaluate these preliminary results to assess if these preliminary results hold up at longer follow up times.

Deflection of light by rotating regular black holes using the Gauss-Bonnet theorem

In this paper, we study the weak gravitational lensing in the spacetime of rotating regular black hole geometries such as Ayon-Beato-Garc\'ia (ABG), Bardeen, and Hayward black holes. We calculate the deflection angle of light using the Gauss-Bonnet theorem (GBT) and show that the deflection of light can be viewed as a partially topological effect in which the deflection angle can be calculated by considering a domain outside of the light ray applied to the black hole optical geometries. Then, we demonstrate also the deflection angle via the geodesics formalism for these black holes to verify our results and explore the differences with the Kerr solution. These black holes have in addition to the total mass and rotation parameter, different parameters as electric charge, magnetic charge, and deviation parameter. Newsworthy, we find that the deflection of light has correction terms coming from these parameters which generalizes the Kerr deflection angle.

REFERENCE VALUES FOR GLENOHUMERAL JOINT ROTATIONAL RANGE OF MOTION IN ELITE TENNIS PLAYERS

Due to the repetitive overhead activity involved in playing tennis and the physical demands of the game, shoulder joint injury is common. There is limited research available describing sport specific risk factors for injury in tennis, however, changes in shoulder rotational range of motion (ROM) have been associated with injury in other overhead 'throwing' type sports. This study had two purposes: i) to identify reference values for passive glenohumeral joint rotational ROM in elite tennis players, and, ii) to investigate differences in ROM between various age groups of players. Cross-sectional analysis. Data was collected at national performance camps held at a National Tennis Centre between September 2012 and July 2015. One hundred and eighty-four tennis players aged between 11 and 24 years took part. All had a top eight national ranking within their respective age group. Participants were divided into three age groups; under 14 years, 14-15 years, and 16 years and over. The main outcome measures were dominant and non-dominant internal and external rotation as well as total glenohumeral joint passive ROM. Reduced internal, and greater external rotation passive ROM were identified on the dominant side (p < 0.05), however, no side-to-side differences in total rotation ROM were found (p > 0.05). A glenohumeral joint internal rotation deficit (GIRD) was prevalent on the dominant side, which increased in magnitude with rising player age. Differences in dominant side internal and external rotation ROM were identified between age groups with the 14-15-year olds having less internal and greater external rotation than the under 14-year olds and the over 16-year old athletes (p < 0.05). The total range of motion values were not found to differ between age groups (p > 0.05). This study provides reference values for glenohumeral joint rotational ROM in elite tennis players and demonstrates age specific differences. Future studies should investigate links between changes in ROM and injury risk. 3.

Modeling the Ionosphere with GPS and Rotation Measure Observations

AbstractThe ionosphere contributes time‐varying Faraday rotation (FR) to radio signals passing through it. Correction for the effect of the ionosphere is important for deriving magnetic field information from FR observations of polarized cosmic radio sources, as well as providing valuable diagnostics of the structure of the ionosphere. In this paper, we evaluate the accuracy of models commonly used to correct for its effects using new observations of pulsars at low frequencies, which provide total rotation measures (RMs) at better precision than previously available. We evaluate models of the ionosphere derived from modern digital ionosondes that provide electron density information as a function of height, as well as GPS‐derived total electron content (TEC) measurements. We combine these density models with reference global magnetic field models to derive ionospheric RM contributions. We find that the models disagree substantially with each other and seek corrections that may explain the differences in RM prediction. Additionally, we compare these models to global TEC models and find that local high‐cadence TEC measurements are superior to global models for ionospheric RM correction.

Geometric Constructibility of Polygons Lying on a Circular Arc

For a positive integer n, an n-sided polygon lying on a circular arc or, shortly, an n-fan is a sequence of $$n+1$$ points on a circle going counterclockwise such that the “total rotation” $$\delta $$ from the first point to the last one is at most $$2\pi $$ . We prove that for $$n\ge 3$$ , the n-fan cannot be constructed with straightedge and compass in general from its central angle $$\delta $$ and its central distances, which are the distances of the edges from the center of the circle. Also, we prove that for each fixed $$\delta $$ in the interval $$(0, 2\pi ]$$ and for every $$n\ge 5$$ , there exists a concrete n-fan with central angle $$\delta $$ that is not constructible from its central distances and $$\delta $$ . The present paper generalizes some earlier results published by the second author and A. Kunos on the particular cases $$\delta =2\pi $$ and $$\delta =\pi $$ .

Filaman Sargılı Cam Elyaf Takviyeli Yarıklı Kompozit Tüplerin Burulma Yükleme Durumu Davranışları

The stress and strain behaviors of filament wound glass-fiber epoxy based cylindrical tube structures made of two different stacking sequences as [(±45°)5] and [(0/ 90)5] were numerically investigated under a constant torque value. The exterior surfaces of tubes were deliberately defected by longitudinally extending, rounded end, 0.6 mm deep, 2 mm wide but varying-length slots. Slot-less and full-length-slot structures were also included in the study. During torsional loading, the variations in stresses, strains and twisting angles of the specified thin-walled composite tube models were investigated, comparatively. Additionally, the effects of fiber winding angles and slot lengths on the specified quantities were parametrically examined. A considerable amount of stress accumulation around the slot tip of both type of tube model is measured which constitute a risk of damage progression. At the innermost laminas, slight fluctuations in the maximum stresses are observed in the slot lengths shorter than 140mm, whereas rapid increases are remarkable for exceeded lengths. On the other hand, the maximum stress changes in the outermost layer are quite uneven. From slot-less to full-length-slot, the change in slot dimensions provokes 8.32 and 9.11 % increments in twisting angles in the 45°/-45° angle-ply and 0°/90° cross-ply structures, respectively. Under the same loading condition, [(±45°)5] stacking sequence gives the structure averagely 0.66° lower total rotation at the specimen tip in comparison to [(0/ 90)5] fiber arrangement.

Reliability of the Cervical Spine Device for the Assessment of Cervical Spine Range of Motion in Asymptomatic Participants

ObjectiveThe purpose of this study was to assess the inter- and intra-assessor reliability of the cervical spine device (Formetric, DIERS International GmbH, Schlangenbad, Germany) in measuring cervical range of motion. MethodsThe cervical spine device was used to measure the cervical range of motion of 65 asymptomatic participants. Flexion-extension, right and left rotation, and right and left lateral flexion were analyzed. Two different assessors performed the measurements on the same day to estimate inter-assessor reliability and 2 days later to examine intra-assessor reliability. Intra-assessor and inter-assessor reliability was assessed using the intraclass correlation coefficient (ICC). The standard error of measurement (SEM) and the smallest detectable difference (SDD) were also estimated. ResultsInter-assessor reliability ICCs for flexion + extension and total lateral flexion movements were >0.90. The ICCs for rotation movements and for left lateral flexion were >0.70. The ICCs for flexion (0.64), extension (0.58), and right lateral flexion (0.56) indicated moderate correlation. Mean SEMs ranged from 2.28° (SDD = 6.31°) for left rotation to 8.08° (SDD = 22.38°) for total rotation. As for intra-assessor test-retest reliability, all ICCs were >0.70. Mean SEMs ranged from 3.14° (SDD = 8.70°) for total lateral flexion to 7.50° (SDD = 20.77°) for extension. ConclusionBoth inter- and intra-observer reproducibility correlation values are moderate to high for measurements obtained using the cervical spine device.

Necessity of law of balance/equilibrium of moment of moments in non-classical continuum theories for fluent continua

In the non-classical theories for fluent continua, the presence of internal rotation rates and their gradients arising due to the velocity gradient tensor necessitate existence of moment tensor. The Cauchy moment tensor acting on the faces of the deformed tetrahedron (derived using Cauchy principle) and the gradients of the rates of total rotations are a rate of work conjugate pair in addition to the rate of work conjugate Cauchy stress tensor and rate of strain tensor. It is well established that in such non-classical continuum theories the Cauchy stress tensor is non-symmetric and the antisymmetric components of the Cauchy stress tensor are balanced by the gradients of the Cauchy moment tensor, balance of angular momenta balance law. In the non-classical continuum theories incorporating internal rotation rates and conjugate Cauchy moment tensor that are absent in classical continuum theories, the fundamental question is “are the conservation and balance laws used in classical continuum mechanics sufficient to ensure dynamic equilibrium of the deforming volume of matter?" If one only considers conservation and balance laws used in classical continuum theories, then the Cauchy moment tensor is non-symmetric. Thus, requiring constitutive theories for the symmetric as well as non-symmetric Cauchy moment tensors. The work presented in this paper shows that when the thermodynamically consistent constitutive theories are used for the symmetric as well as antisymmetric Cauchy moment tensors, non-physical and spurious solutions result even in simple flows. This suggests that perhaps the additional conjugate tensors resulting due to the presence of internal rotation rates, namely the Cauchy moment tensor and the antisymmetric part of Cauchy stress tensor, must obey some additional law or restriction so that the spurious behavior is precluded. The paper demonstrates that in the non-classical theory with internal rotation rates considered here the balance of moment of moments balance law and the equilibrium of moment of moments are in fact identical. When this balance law is considered, the Cauchy moment tensor becomes symmetric, hence eliminating the constitutive theory for the antisymmetric Cauchy moment tensor and thereby eliminating spurious and non-physical solutions. The necessity of this balance/equilibrium law is established theoretically, its derivation is presented using rate considerations, and its necessity is also demonstrated by a model problem using thermoviscous incompressible fluid as an example. The findings reported in this paper hold for all fluent continua, compressible as well as incompressible.

Atlanto-Occipital Synostosis in a Colombian Population Sample

Introduction The Cervico-capital rotation process involves important joints with respect to the neurological field. Among these joints, the atlanto-occipital joint accounts for 40% of the total rotation process and its anatomical changes may affect the joint, i.e when the synostosis of both bones occurs. This anomaly has a reported incidence in the world population of 0.14% to 0.75%. To determine whether this incidence range also corresponds to the Colombian population, atlanto-occipital fusion in Colombian patients was studied. Materials and Methods The presence of atlanto-occipital fusion was assessed in a random sample of 105 skulls of a Colombian population. Morphometric features were evaluated by using a Vernier caliper. Results Out of the total sample two cases of atlanto-occipital fusion were identified. One of them exhibited a bilateral fusion between the anterior arch of the foramen magnum and the lateral masses of the atlas; the other one exhibited a left hemisynostosis that compromises the anterior arch foramen magnum and left lateral mass of atlas. The overall frequency of occurrence was 1.9%. Conclusion A greater incidence of atlanto-occipital fusion was found in contrast to the range of world incidence reported in the literature.

Validity of an Alternate Hand Behind Back Shoulder Range of Motion Measurement in Patients With Shoulder Pain and Movement Dysfunction

ObjectivesThe purpose of this study was to determine the criterion-related validity of a novel method of measuring hand behind back (HBB) shoulder range of motion (ROM) for evaluating pain and disability in people with shoulder pain and movement impairment. MethodsThis cross-sectional study design evaluated shoulder ROM, pain, fear-avoidance beliefs, and disability in 60 people (aged 35-70 years, 31 male) with chronic unilateral shoulder dysfunction (mean duration 15.73 weeks). Shoulder HBB ROM was measured with a bubble inclinometer in a manner that did not require the patient to disrobe. Correlations were sought between HBB ROM and other shoulder movements, as well as scores recorded on the Shoulder Pain and Disability Index (SPADI), visual analogue scale for pain, Fear Avoidance Beliefs Questionnaire (FABQ), and duration of symptoms. ResultsRestriction of HBB movement was significantly correlated with SPADI total disability score (r = 0.39, P < .01), flexion ROM (r = 0.30, P < .05), abduction ROM (r = 0.39, P < .01), and external rotation ROM (r = 0.60, P < .01). Other variables were not significantly correlated with HBB ROM. Multiple linear regression analysis indicated that the variance in HBB ROM was explained by the SPADI disability subscore (P = .01) but not by visual analogue scale score (P = .05), FABQ score (P = .65), or duration of symptoms (P = .73). The FABQ score was not explained by limitation in HBB ROM and shoulder movements. ConclusionThese findings suggest that this novel method of measuring HBB ROM could be used as a functional outcome measure in the evaluation of patients with shoulder disorders. This method could be considered as an additional or alternative where there are challenges in measuring HBB because of restrictions in undressing a patient, such as for cultural reasons.