Angle Of Take-off Research Articles

Angiographic characteristics and treatment approach in patients undergoing intra-arterial chemotherapy for retinoblastoma.

To identify the specific clinical and angiographic variables that determine the success of intra-arterial chemotherapy (IAC) in a patient with retinoblastoma. Medical records from patients undergoing intra-arterial chemotherapy for the treatment of retinoblastoma between January 2015 and June 2020 within a large academic ocular oncology practice were retrospectively reviewed. Demographics were recorded together with clinical, ocular, and angiographic variables such as the diameter of the ophthalmic artery (OA), angle of ophthalmic artery takeoff, and branching pattern of ophthalmic vasculature. Forty-four eyes from 33 patients with retinoblastoma treated with IAC were identified. Over the total 32 mean months of follow-up, these patients received 144 total catheterizations and a mean of 3.2 IAC cycles for each eye. The number of IAC cycles and the chemotherapeutic agent used did not vary significantly with worsening International Classification of Retinoblastoma (ICRB) groups (P > 0.1). Cumulative dose did not vary with the ICRB group for eyes treated with melphalan, topotecan, or carboplatin (P > 0.1). A higher ICRB group was associated with a smaller mean ophthalmic artery diameter across all procedures (P = 0.016), and femoral artery diameter did not vary significantly between ICRB groups (P = 0.906). A higher cumulative dose of IAC was significantly associated with a smaller takeoff angle of the OA (melphalan, P = 0.011; topotecan, P = 0.009; carboplatin, P = 0.031) in patients who underwent successful IAC procedures. Ophthalmic artery diameter and femoral artery diameter did not have a significant association (P > 0.1) with higher IAC doses in successful IACs. Cumulative IAC dose was not significantly associated with ophthalmic vasculature branching pattern, presence of choroidal blush, temporary OA vasospasm reported during the procedure, and OA occlusion upon microcatheter placement. In this study, neurosurgical angioanatomy appeared to influence the cumulative dose of chemotherapy needed during IAC for retinoblastoma. In the future, these anatomic variables may be used to guide the frequency of monitoring, dosing, and estimation of recurrence risk.

Study of coronary sinus anatomy during levophase of coronary angiography.

BACKGROUNDCoronary sinus (CS) imaging has recently gained importance due to increasing need for mapping and ablation of electrophysiological arrhythmias and left ventricular (LV) pacing during cardiac resynchronization therapy (CRT). Retrograde venogram is the current standard for imaging CS and its tributaries. AIMTo evaluate CS anatomy during levophase of routine coronary angiography to aid LV lead implantation during CRT.METHODSIn this prospective observational study, 164 patients undergoing routine coronary angiography for various indications (Chronic stable angina-44.5%, acute coronary syndrome- 39.5%, Dilated cardiomyopathy-11%, atypical chest pain-5%) were included. Venous phase (levophase) of left coronary injection was recorded in left anterior oblique - cranial and right anterior oblique -cranial views. Visibility of coronary veins, width and shape of CS ostium, angulations of proximal CS with body of CS were noted. Presence, size, take-off angle and tortuosity of posterolateral vein (PLV), anterior interventricular veins (AIV) and middle cardiac vein (MCV) were also noted.RESULTSDuring levophase, visibility grade (Muhlenbruch grade) for coronary veins was 3 in 74% and 2 in 26% of cases. Visibility of CS did not correlate with body mass index. The diameter of CS ostium was < 10 mm, 10-15 mm and > 15 mm in 48%, 42% and 10% of patients respectively. Proximal CS was tubular in 136 (83%) patients and funnel-shaped in 28 (17%) patients. Sharp take-off angulation between ostium and body of CS was seen in 16 (10%) patients. Two or more PLV were present in 8 patients while PLV was absent in 52 (32%) patients. Angle of take-off of PLV with body of CS was favourable (0°-45°) in 65 (40%) patients. The angle was 45°-90° in 36 patients and difficult take-off angle (> 90°) was seen in 8 patients. Length of PLV reached distal third of myocardium in 84 cases and middle third in 11 cases. There was no tortuosity in 79 cases, a single bend in 29 cases and more than 2 bends in 4 cases. Thirty nine (24%) patients had other veins supplying posterior/Lateral wall of LV. There was a single vein supplying lateral/posterior wall in 31 (19%) patients. Diameter of MCV and AIV was significantly larger in patients with absent PLV as compared to patients with a PLV. CONCLUSIONLevophase study of left coronary injection is effective in visualization of the CS in almost all patients undergoing coronary angiography and may be an effective alternative to retrograde venogram in patients with LV dysfunction or LBBB.

Kinematics of the Final Approach and Take-Off Phases in World-Class Men and Women Pole Vaulters

The pole vault is a highly technical event where the athletes must successfully convert horizontal velocity during the run-up to vertical velocity at take-off. The aim of this study was to compare the kinematics of men's and women's world-class pole vaulting. Video data were collected of the best clearances by 14 men and 11 women at the 2018 IAAF World Indoor Championships using three high-speed cameras (200 Hz). Running velocity, step lengths, step times, and pole angles were measured during the run-up; during take-off, distance from the plant box, angle and velocity of take-off, and relative positions of the foot and hands were measured. Men achieved greater clearance heights with faster run-ups, faster take-off velocities and higher hand grip positions (all p < 0.001), with each of the last three steps longer for men when expressed as absolute values (all p < 0.001), but not when expressed relative to stature. There were no differences in run-up pole angles, step times, take-off angle, take-off contact time or time from pole plant to take-off. Women differed in their approach and take-off for characteristics affected by stature and strength, such as fewer run-up steps, shorter take-off distances, and lower grip heights. These lower grips result from a shorter, lighter pole, and this disadvantage was greater than slower run-up velocities. Coaches should therefore note that sex-based differences occur in the pole vault that result from anthropometric differences, but which do not negate the adoption of similar technical models of vaulting.

Four-Step Classification of Endoscopic Transpapillary Gallbladder Drainage and the Practical Efficacy of Cholangioscopic Assistance.

Background/AimsAlthough endoscopic transpapillary gallbladder drainage (ETGBD) has been reported as an alternative procedure for acute cholecystitis, it requires advanced endoscopic techniques. In terms of the certainty of achieving drainage, it remains a challenging procedure. The aim of the current study was to elucidate the practical efficacy of cholangioscopic assistance and to develop a new classification that could be used to evaluate the technical difficulty of ETGBD and provide a theoretical strategy to apply cholangioscopy appropriately for difficult ETGBD.MethodsA total of 101 patients undergoing ETGBD were retrospectively studied. The characteristics and technical outcomes of ETGBD with conventional ETGBD (C-ETGBD) and SpyGlass DS-assisted ETGBD (SG-ETGBD) were evaluated. The characteristics and technique-dependent factors of unsuccessful C-ETGBD/SG-ETGBD were evaluated using the classification based on the steps of the procedure. The predictive factors of successful C-ETGBD/SG-ETGBD were examined.ResultsC-ETGBD was successful in 73 patients (72.3%). SG-ETGBD was successful in 11 of 13 patients (84.6%) who had C-ETGBD failure. Optional SG-ETGBD significantly increased the final success rate (94.1%) compared to C-ETGBD alone (p=0.003). ETGBD procedures could be classified into four steps. SG-assistance worked as an excellent troubleshooter in step 1 (failure to identify the cystic duct orifice) and step 2 (failure of guidewire advancement across the downturned angle of cystic duct takeoff). Magnetic resonance cholangiopancreatography could provide predictive information based on the classification.ConclusionsOptional SG-ETGBD achieved a significantly higher success rate than C-ETGBD alone. Step classification is helpful for determining the technical difficulty of ETGBD and developing a theoretical strategy to apply cholangioscopy in a coordinated manner. (Gut Liver 2021;15-485)

Dikey Kalkış ve İniş Sistemi Modeli için Yapay Sinir Ağı Tabanlı Uyarlanır PID Kontrolör Tasarımı

This study presents an artificial neural network (ANN) based adaptive proportional integral derivative (PID) controller algorithm which is developed to control the pitch angle of the vertical takeoff and landing (VTOL) system model. To find appropriate conventional PID controller parameters, either step response or vibration method might be used in a way of the widely used approach. They provide constant values for the conventional PID controller parameters for a closed-loop system however it is obvious that the unsatisfied tracking error performances in the closed-loop system might be addressed as a problem to be optimized. To overcome this problem, the parameters of the proposed adaptive PID controller might be determined with an ANN constructed feedforward multilayer perceptron. The proposed controller algorithm possesses the gradient descent with momentum update rule for the adaptiveness of the obtained PID parameters. The proposed adaptive PID controller algorithm is tested for the pitch angle of the VTOL system model in the MATLAB/Simulink environment in terms of the sinusoidal and step signals as the desired outputs. The obtained results are compared to the conventional PID controller whose parameters are tuned by Simulink PID tuner application in terms of mean square error, integral absolute error, the settling time, and the percentage overshoot.

Horse vision and obstacle visibility in horseracing

Visual information is key to how many animals interact with their environment, and much research has investigated how animals respond to colour and brightness information in the natural world. Understanding the visibility of features in anthropogenic environments, and how animals respond to these, is also important, not least for the welfare and safety of animals and the humans they co-exist with, but has received comparatively less attention. One area where this is particularly pertinent is animal sports such as horseracing. Here there is a need to understand how horses see and respond to obstacles, predominantly fences and hurdles, as this has implications for horse and rider safety, however obstacle appearance is currently designed to human perception. Using models of horse colour and luminance (perceived lightness) vision, we analysed the contrast of traditional orange markers currently used on fences from 11 UK racecourses, and compared this to potential alternative colours, while also investigating the effect of light and weather conditions on contrast. We found that for horses, orange has poor visibility and contrast against most surroundings. In comparison, yellow, blue, and white are more conspicuous, with the degree of relative contrast varying with vegetation or background type. Results were mostly consistent under different weather conditions and time of day, except for comparisons with the foreground turf in shade. We then tested the jump responses of racehorses to fences with orange, fluorescent yellow, bright blue, or white takeoff boards and midrails. Fence colour influenced both the angle of the jump and the distances jumped. Bright blue produced a larger angle of takeoff, and jumps over fluorescent yellow fences had shorter landing distances compared to orange, with bright blue fences driving a similar but non-significant trend. White was the only colour that influenced takeoff distances, with horses jumping over white fences having a larger takeoff distance. Overall, our results show that current obstacle coloration does not maximise contrast for horse vision, and that alternative colours may improve visibility and alter behavioural responses, with the ultimate goal of improving safety and welfare.

Aircraft Take-off and Landing Performance Calculation Method Based on Flight Simulation

In order to comply with the existing standard requirements or specifications, a new computational method for aircraft take-off and landing performance, which deals with the characteristics of the high precision of parameters in the process of take-off and landing based on flight simulation technique. The simulation model for a twin-engine normal layout aircraft is constructed in detail, including nonlinear motion equation, aerodynamic, engine, landing gear and dynamical mass model. According to performance calculation standard and pilot control specification for different take-off modes and landing stages, the simulation process for one engine inoperative(OEI) take-off, angle of attack(AoA) hold take-off, standard take-off, reject take-off and landing are designed, and corresponding performance computer software is developed to achieve the goal of accuracy as well as full parameters calculation. Compared with the existing methods, the computational complexity of this method is increased, the process is detailed, the parameters are increased, and more influencing factors can be analyzed quantitatively. Results show that OEI take-off distance is the longest, standard take-off is suitable for light aircraft, angle of attack hold take-off is appropriate in plateau or limited thrust. Landing distance is related to glide angle. Therefore, light aircraft landing can reduce the approach speed and increase the glide angle.

Coding of coronary arterial origin and branching in congenital heart disease: The modified Leiden Convention

ObjectivesVariations in coronary anatomy are common and may relate to the position of the coronary ostium relative to the aortic sinus, the angle of coronary take-off, or the course of the coronary arterial branches. Several classification systems have been proposed. However, they all lack a simple rationale that is applicable irrespective of the relative position of the great arteries, as well as in bicuspid aortic valves. We present a modification of a relatively simple system introduced in the early 1980s, designated the “Leiden Convention.” MethodsThe first step of the Leiden Convention is that the clinician takes position in the nonfacing sinus of the aorta looking toward the pulmonary orifice. The right-hand facing sinus is sinus 1, and the left-hand facing sinus is sinus 2. The coronary branches arising from sinus 1 are annotated proceeding in a counterclockwise fashion toward sinus 2. “Usual” (normal) coronary anatomy would be 1R-2LCx. Given their clinical relevance, single sinus coronary arteries are discussed separately. ResultsThis system was originally designed and highly applicable in hearts with an altered great artery relationship, such as in the variable and complicated patterns seen in transposition of the great arteries and double outlet right ventricle. The modified system also can be used in cases with normally related great arteries, cases with single sinus coronary arteries, and cases with bicuspid aortic valves. ConclusionsThe modified Leiden Convention is not a strict classification but a simple coronary coding system that is broadly applicable.

Crusade Microcatheter-Facilitated Reverse Wire Technique for Revascularization of Bifurcation Lesions of Coronary Arteries.

This study aims to analyze the lesion characteristics of bifurcations that required reverse wire technique and the efficacy and safety of this technique in approaching branches with a highly angulated take-off. We enrolled patients in whom reverse wire technique was used after failed conventional antegrade wiring with the support of a Crusade catheter. The study endpoints were the technical success defined as succeeding in sending the reversely bent wire to the targeted branches without complications and the procedural success defined as succeeding in revascularization of the bifurcation lesions without complications. Among 158 patients with bifurcation lesions undergoing percutaneous coronary intervention using a Crusade catheter to facilitate wiring, 23 (14.6%) requiring the reverse wire technique in an attempt to access branches of the bifurcation lesions with an acutely angulated take-off were enrolled for analysis. The obtainable angle of take-off was 162.9 ± 4.7 degrees. For the parent vessel, the ostium of the targeted branch, and nontargeted branch, the minimal luminal diameters were 0.3 ± 0.5 mm, 0.4 ± 0.2 mm, and 1.8 ± 0.5 mm, respectively; the diameter stenosis were 88.8 ± 18.5%, 83.0 ± 7.3%, and 32.0 ± 14.5%, respectively. Technical and procedural success was achieved in 22 cases (96% for both). We showed in the present study that the reverse wire technique is effective and safe for approaching highly angulated branches of bifurcation lesions and consequently for complete revascularization of difficult bifurcation lesions.

Body composition and kinematic analysis of the grab start in youth swimmers.

The purposes of this study were to compare the kinematic variables in youth swimmers during the grab start between sexes and to investigate the relationship between body composition and kinematic variables of the participants. Six female (Mage = 13.71 ± 0.49 yrs) and seven male (Mage = 14.00 ± 1.07 yrs) swimmers participated in this study. All participants were required to perform grab start tests in random order (three trials by each participant), while the best attempt was analyzed. Nineteen kinematic parameters consisting of block time, flight time, flight distance, total time, total distance, horizontal and vertical displacement of the center of mass (CM) at take-off, horizontal and vertical displacement of the CM at entry, height of take-off and entry, relative height of take-off, horizontal and vertical velocity of the CM at take-off, horizontal and vertical velocity of the CM at entry, angle of take-off, angle of entry and angle of knee at block were analyzed. Out of the 19 evaluated kinematic parameters, a statistical difference between the female and male group was found only in the total distance. Therefore, both female and male groups are considered as only one group and merged after analyzing the results. Statistical analysis showed positive and negative correlations between horizontal / vertical velocity of CM at take-off and several kinematic variables (e.g. angle of entry (rhorizontal = −.868, p=.000 / rvertical = .591, p=.02), total distance (rhorizontal = .594, p=.02 / rvertical = .54, p=.04), and height of take-off (rvertical = .888, p=.000), respectively). On the other hand, positive and negative correlations were found between somatotype components and several kinematic variables (e.g. horizontal displacement of CM at entry (rendomorphy = −.626, p=.013), angle of entry (rmesomorphy = −.686, p=.005 / rectomorphy = .52, p=.047), total distance (rendomorphy = −.626, p=.012), and height of take-off (rendomorphy = −.633, p=.011 / rectomorphy = .515, p=.05)). In conclusion, results show that in order to be successful at grab start performance, a swimmer should target to get higher horizontal velocity of CM at take-off and optimize the angle of take-off so this movement form supplies more total distance to the swimmer. Coaches should consider improving start performance and adding start training to regular training sessions. Moreover, youth male and female swimmers can participate together in the grab start training.

Accessory vein obliteration criteria for immature fistulae: a modest proposal for an old paradigm.

Venous stenosis and/or presence of accessory vein (av) are the two most common causes of early fistula failure. While treatment of stenosis is better defined, there are no clear criteria for obliteration of the av. Often, interventionalists rely on visual assessment of flow through the av and its diameter (significant if > 1/3 of the main fistula diameter) for intervention. The purpose of this study was to establish objective criteria for the management of av. Various computational fluid dynamics simulations were performed to analyze blood flow in the arteriovenous fistula (AVF). av of different diameters and angles was then added at various locations in the AVF and comparison of simulation results was undertaken. The computational model revealed that when the av was 33% of the diameter of the AVF, flow in av was only 7%. When diameter of the av was increased to 50% and 66% of the diameter of the AVF, flow through the av was 10% and 31% of the flow in main AVF, respectively. Location or angle of take-off of av did not alter flow. This report provides objective information regarding criteria for av obliteration. It needs to be further validated in randomized clinical trials.

Anomalous aortic origin of coronary arteries: 'anatomical' surgical repair

Anomalous aortic origin of coronary arteries (left coronary from right sinus or right coronary from left sinus) is a rare congenital defect, which carries a high risk of sudden cardiac death. The risk is particularly high when the interarterial course between the great arteries has an intramural segment, or is hypoplastic/stenotic, or has an abnormal orifice. Various surgical techniques have been used, including coronary artery bypass grafting, pulmonary artery translocation, partial or complete unroofing of the intramural course and patch enlargement of the interarterial course. We favour 'anatomical' repair that creates an enlarged neo-ostium into the appropriate sinus, eliminates completely the intramural segment and restores a normal angle of take-off. Reimplantation of the anomalous coronary artery may be indicated in variants without an intramural course. Surgical correction is mandatory for symptomatic and asymptomatic patients with evidence of myocardial ischaemia under stress; it is recommended in asymptomatic patients with high-risk variants (anomalous left coronary artery with the intramural course), particularly in young patients with strenuous activities.

Prevalence and Characteristics of Coronary Anomalies Originating from the Opposite Sinus of Valsalva in 8,522 Patients Referred for Coronary Computed Tomography Angiography

Although coronary computed tomographic angiography has the ability to depict potentially malignant features of anomalous coronary artery originating from the opposite sinus of Valsalva (ACAOS), there are limited data on the significance of ACAOS in the computed tomography population. The aims of this study were to assess the prevalence of ACAOS and to correlate its anatomic features with patients' symptoms among 8,522 consecutive subjects who underwent coronary computed tomographic angiography from February 2008 to May 2012. The ACAOS proximal course was classified into anterior, interarterial, septal, and retroaortic subtypes. Malignant ACAOS was recorded if a slitlike ostium, an acute angle of takeoff, an intramural course, and significant compression between the aorta and pulmonary trunk were present simultaneously. The prevalence of ACAOS was 0.84% (72 of 8,522), including right-sided origins of the left main coronary artery (n = 11), left anterior descending coronary artery (n = 9), and left circumflex coronary artery (n = 33) and left-sided origin of the right coronary artery (n = 20). Of the 24 ACAOS (0.28%) with an interarterial course, 12 (0.14%) showed significant vessel compression, of which 6 (0.07%) were classified as malignant. The presence of significant interarterial compression and malignant ACAOS type were observed in left-sided right coronary arteries only, and interarterial compression correlated with patients' symptoms at a median of 15-month follow-up. In conclusion, the computed tomographic prevalence of ACAOS seems to be comparable with that of previous angiographic studies. The malignant features of ACAOS in the adult computed tomography population might be exclusively associated with left-sided right coronary arteries.

Aircraft Takeoff Simulation with MATLAB

There are three primary ways for an aircraft to change its orientation relative to the passing air. Pitch (movement of the nose up or down, rotation around the transversal axis), Roll (rotation around the longitudinal axis, that is, the axis which runs along the length of the aircraft) and Yaw (movement of the nose to left or right, rotation about the vertical axis). In straight climbing flight, lift is less than weight. At first, this seems incorrect because if an aircraft is climbing it seems lift must exceed weight. When an aircraft is climbing at constant speed it is its thrust that enables it to climb and gain extra potential energy. Lift acts perpendicular to the vector representing the velocity of the aircraft relative to the atmosphere, so lift is unable to alter the aircraft's potential energy or kinetic energy. This can be seen by considering an aerobatic aircraft in straight vertical flight - one that is climbing straight upwards (or descending straight downwards). Vertical flight requires no lift! When flying straight upwards the aircraft can reach zero airspeed before falling earthwards - the wing is generating no lift and so does not stall. In straight, climbing flight at constant airspeed, thrust exceeds drag. In straight descending flight, lift is less than weight. In addition, if the aircraft is not accelerating, thrust is less than drag. In turning flight, lift exceeds weight and produces a load factor greater than one, determined by the aircraft's angle of bank Take off is the stage from the application of take off power until an altitude of 35 feet above the runway elevation. This includes the substages: takeoff and rejected takeoff. The initial climb is the stage from the end of the takeoff to the first prescribed power reduction or when the aircraft is 1,000 feet above the runway elevation, whichever is first.

An effect of vegetation structure on carcass exploitation by vultures in an African savanna

Carcass utilisation by vultures may be constrained by the surrounding vegetation, as high vegetation densities may leave insufficient space for the vultures to take-off. We tested this by placing carcasses at 14 sites differing in density and height of the surrounding vegetation. African White-backed Vultures Gyps africanus were reluctant to land at carcasses from which the angle required to clear the surrounding vegetation on take-off was greater than 6°, and Cape Vultures Gyps coprotheres were not observed on carcasses from which the required angle of take-off was greater than 4°. Increasing vegetation densities due to bush encroachment may therefore affect the two species to different extents.

CYBERKNIFE STEREOTACTIC RADIOSURGICAL RHIZOTOMY FOR TRIGEMINAL NEURALGIA

Abstract OBJECTIVE To search for correlations between specific anatomic, geometric, and morphological properties of the trigeminal nerve and the success of radiosurgical treatment and elimination of facial hypesthesia as a complication. METHODS Forty-six patients with at least 6 months of follow-up after CyberKnife (Accuray, Inc., Sunnyvale, CA) rhizotomy were retrospectively reviewed. Patients treated after 2004 were entered into the study after congruity in treatment parameters was established. Anatomic variations regarding the length of each nerve segment and angle of trigeminal nerve takeoff from brainstem to Meckel's cave in the axial and sagittal planes were studied. Dose distribution to surrounding critical structures (brainstem and trigeminal ganglion) was measured. After spatial relationships of involved structures and dose distributions were recorded, their relationship to treatment success, failure, or complication (primarily facial numbness) was tabulated. RESULTS Forty-five patients (97.2%) experienced pain relief immediately or within weeks. Thirty-four patients maintained excellent outcome. Some degree of facial numbness developed in 18 patients (39.1%) and was mild in 11 of them (Grade II on the Barrow Neurological Institute scale). Patients with a sagittal-angle trigeminal nerve takeoff from the brainstem in the range of 150 to 170 degrees measured from the horizontal plane had a more favorable outcome (P = 0.03) than patients with less obtuse relationships to the proximal nerve origin. Patients who received higher doses of radiation to the brainstem/dorsal root entry zone of the trigeminal nerve experienced a higher rate of posttreatment facial anesthesia. CONCLUSION There may be important anatomic and geometric relationships between the treated trigeminal nerve and surrounding critical structures that warrant pretreatment target volume placement and dose distribution considerations.

The Optimum Angle of Takeoff in Long Jump with Vertical Displacement at Landing

In long jump, it is possible to estimate a distance between takeoff and landing by assuming that the center of mass of a long jumper in aerial phase moves along a trajectory of projectile. Based on the assumption, we obtain an approximate trajectory of the jumper as a perturbed solution of flat aerial path, in which the effect of air drag is included as the linear form. Also, a maximization problem is formulated from the trajectory and the optimum angle of takeoff is theoretically derived. Then, we introduce two parameters, the horizontal velocity of the center of mass and the takeoff velocity into the present model of takeoff. In particular, the solution of the optimum angle includes the effect of vertical displacement at landing which affects significantly a distance of the aerial phase. The distance of the aerial phase and the takeoff angle are estimated in several cases of measured data. The results of the estimation show the effectiveness of the present solutions.

B13 着地時の重心低下を考慮した走り幅跳びの最適踏切角(跳躍)

An approximate trajectory of the center of mass for a long jumper is obtained based on the expression of flat aerial path and the optimum angle of takeoff is derived theoretically. Then, we introduce two parameters, the horizontal velocity of the center of mass and the takeoff velocity into the present model of takeoff. In particular, the solution of the optimum angle includes the effect of vertical displacement at landing which affects significantly a distance of the aerial phase. The distance of the aerial phase and the takeoff angle are estimated in several cases of measured data. The results of the estimation show the effectiveness of the present model.

Jumping in frogs: assessing the design of the skeletal system by anatomically realistic modeling and forward dynamic simulation.

Comparative musculoskeletal modeling represents a tool to understand better how motor system parameters are fine-tuned for specific behaviors. Frog jumping is a behavior in which the physical properties of the body and musculotendon actuators may have evolved specifically to extend the limits of performance. Little is known about how the joints of the frog contribute to and limit jumping performance. To address these issues, we developed a skeletal model of the frog Rana pipiens that contained realistic bones, joints and body-segment properties. We performed forward dynamic simulations of jumping to determine the minimal number of joint degrees of freedom required to produce maximal-distance jumps and to produce jumps of varied take-off angles. The forward dynamics of the models was driven with joint torque patterns determined from inverse dynamic analysis of jumping in experimental frogs. When the joints were constrained to rotate in the extension-flexion plane, the simulations produced short jumps with a fixed angle of take-off. We found that, to produce maximal-distance jumping, the skeletal system of the frog must minimally include a gimbal joint at the hip (three rotational degrees of freedom), a universal Hooke's joint at the knee (two rotational degrees of freedom) and pin joints at the ankle, tarsometatarsal, metatarsophalangeal and iliosacral joints (one rotational degree of freedom). One of the knee degrees of freedom represented a unique kinematic mechanism (internal rotation about the long axis of the tibiofibula) and played a crucial role in bringing the feet under the body so that maximal jump distances could be attained. Finally, the out-of-plane degrees of freedom were found to be essential to enable the frog to alter the angle of take-off and thereby permit flexible neuromotor control. The results of this study form a foundation upon which additional model subsystems (e.g. musculotendon and neural) can be added to test the integrative action of the neuromusculoskeletal system during frog jumping.

Neonatal truncus arteriosus repair: Surgical techniques and clinical management

Truncus arteriosus is now ideally repaired in the neonatal period with low morbidity and mortality. Published reports have documented mortality rates in the range of 4% to 5% with mean age at repair as low as 11 days. The physiologic basis for improved outcomes with earlier repair is the avoidance of damaging sequelae of pulmonary overcirculation and heart failure. Data show that baseline mean pulmonary artery pressure is lower in infants undergoing earlier repair. Improved operative outcomes also have been achieved with aggressive truncal valve repair versus replacement in the presence of truncal valve dysfunction, right ventricular outflow tract reconstructive techniques that are patient anatomy-specific, and use of regional perfusion techniques for repair of associated interrupted aortic arch. In addition, a heightened awareness of anomalies of coronary artery ostial location, number, angle of takeoff, and degree of patency can result in avoidance of inadvertent injury to the artery and associated myocardial insult. Copyright © 2002 by W.B. Saunders Company