The impact of lateral bow angle variation on an archer’s score

Variation of the bow’s lateral angle (‘bow cant’ angle) affects the lateral position of arrows on the target, thus impacting an archer’s score. The displacement of arrows on the target depends approximately on the target distance squared and is hence of greatest impact at longer distances. A total of eight archers participated in this study, ranging in skill level from three who have performed at the highest levels internationally through to competent club-level archers, plus the author. The bow cant variation was measured and the impact on archers’ scores was calculated, assuming no other score loss mechanisms. The results show that the score loss associated with bow cant angle can be a substantial portion of an archer’s total score loss, particularly for elite archers using recurve bows.

Second sacral sacralalar‐iliac (S2AI) screw placement in adult degenerative scoliosis (ADS) patients: an imaging study

Background The imaging characteristics of sacral sacralalar-iliac (S2AI) screw trajectory in adult degenerative scoliosis (ADS) patients will be determined. Methods S2AI screw trajectories were mapped on three-dimensional computed tomography (3DCT) reconstructions of 40 ADS patients. The starting point, placement plane, screw template, and a circle centered at the lowest point of the ilium inner cortex were set on these images. A tangent line from the starting point to the outer diameter of the circle was selected as the axis of the screw trajectory. The related parameters in different populations were analyzed and compared. Results The trajectory length of S2AI screws in ADS patients was 12.00 ± 0.99 cm, the lateral angle was 41.24 ± 3.92°, the caudal angle was 27.73 ± 6.45°, the distance from the axis of the screw trajectory to the iliosciatic notch was 1.05 ± 0.81 cm, the distance from the axis of the screw trajectory to the upper edge of the acetabulum was 1.85 ± 0.33 cm, and the iliac width was 2.12 ± 1.65 cm. Compared with females, the lateral angle of male ADS patients was decreased, but the trajectory length was increased (P < 0.05). Compared to patients without ADS in previous studies, the lateral angle of male patients was larger, the lateral angle of female patients was increased, and the caudal angle was decreased (P < 0.05). Conclusions There is an ideal trajectory of S2AI screws in ADS patients. A different direction should be noticed in the placement of S2AI screws, especially in female patients.

Digits Angle and Digits Length Ratio in Japanese Quail (Coturnix coturnix Japonica)

Background: Digit lengths are dimorphic in some other creatures as in humans. In particular, gender analysis can be done using the ratio between the second finger (D2) and the fourth finger (D4). The aim of this study is to examine whether the ratio of foot fingers is related to gender in Japanese quail (Coturnix coturnix japonica).Methods: In this study, 60 adults (30 female and 30 male) Japanese quail foot digit length ratios were examined in relation to gender. The ratios of the lengths of the second finger (D2), the third finger (D3) and the fourth finger (D4) to each other were taken on the computer. Result: In addition, geometrical analysis of base posture positions between female and male individuals were made and shape differences were revealed. It was observed that the second finger (D2) of male birds was more introverted than in females. It was seen that Principal component analysis (PCA1) explained 53.07% of the total variation between female and male groups. PCA2 explained 17.6% of the total variation and PCA3 announced 11.83%. In statistical morphometric analysis, the difference in shape between the male and female was statistically insignificant. D2:D3, D2:D4 and D3:D4 ratios were higher in males. It was observed that the lateral angle in both genders was higher than medial angle. This difference was statistically significant (p less than 0.001). While the average of the lateral angle was 50.89% in all individuals, the average of the medial angle was 42.81%. The highest length in all individuals belonged to the third finger. It was observed that the ratio of D2:D4 among females used in the study was 0.867 in females and 0.877 in males.

Trajectory of Lumbar Translaminar Facet Screw Under Navigation: A Cadaveric Study

Study Design: Anatomic cadaver study. Objective: Translaminar facet screw fixation supplements unilateral pedicle screw-rod fixation in minimally invasive transforaminal lumbar interbody fusion (TLIF). Various screw diameters, lengths, trajectories, and insertion points are used; however, they do not represent true screw trajectory. We aimed to evaluate lumbar laminar anatomy and suggest a safe and effective insertion point and trajectory during lumbar-translaminar facet screw fixation in an anatomic cadaver study. Methods: O-arm navigation simulating the true translaminar facet screw trajectory was used to evaluate L1-S1 in cadaveric spines. The inner and outer diameters, length, and trajectory of the screw pathway were measured along the trajectory from the spinous process base through the contralateral lamina, crossing the facet joint to the transverse process base using 2 starting points: cephalad one-third (1/3SL) and one-half (1/2SL) of the spinolaminar junction. Results: Using the 1/2SL starting point, the outer and inner lamina diameters did not differ significantly from L1-L5 (7.47 ± 1.38 to 6.7 ± 1.84 mm and 4.73 ± 1.04 to 3.86 ± 1.46 mm, respectively). Screw length (36.16 ± 4.02 to 49.29 ± 10.07 mm) and lateral angle increased (50.28° ± 8.78° to 60.77° ± 8.88°), but caudal angle decreased (16.19° ± 9.01° to 1.13° ± 11.31°). Lamina diameter and screw length did not differ with different starting points. L2-L3 caudal angles were lower in the 1/2SL starting point. Conclusion: A 36- to 50-mm translaminar facet screw—with 5.0-mm diameter for L1-L2 and 4.5-mm diameter for L3-L5—can be inserted at the middle of the spinolamina, especially during minimally invasive TLIF, with a 50° to 60° lateral angle relative to the spinous process, and a caudal angle of 16° to 1° relative to the spinolamina from L1-L5.

Morphometric parameters of clavicles among adult Black people in Tanzania

Morphological clavicular variation has been studied extensively by orthopaedic surgeons, anatomic and forensic experts to explain developmental, gender and age-related differences. The design of fixation devices for displaced clavicular fracture management depends largely on anatomic characteristics of clavicle. Eighty-one unpaired clavicles of unknown sex were studied, 42 clavicles were of right side and 39 clavicles of left side. All the clavicles were collected from adult cadavers which were dissected in Departments of Anatomy at Muhimbili and Herbert Kairuki Memorial Universities. The length of clavicle was measured by a vernier calliper; the middle point of this length was taken as the point where midclavicular circumference was measured with the help of a measuring thread and the angle of curvature of clavicle was measured by using protractors. The average lengths of the left and right clavicles were 15.23±1.12 cm and 15.43±1.01cm respectively. The average medial angle of curvature of left clavicle was 155.33° ± 4.39°and that of right clavicle was 153.40° ± 3.96°. The mean total angle of curvature of left clavicle was 293.54˚± 9.55°and the average total angle of curvature of right clavicle was 290.05±8.94°. The average midclavicular circumference of left clavicle was 3.88cm ± 0.33cm and that of right clavicle was 3.94cm±0.33cm. The right clavicle was longer than the left clavicle, the average medial angle of curvature of left clavicle was greater than medial angle of right clavicle, the average lateral angle of curvature of left clavicle was more than the average lateral angle of curvature of right clavicle and the mean of midclavicular circumference of right clavicle was greater than that of left clavicle. Keywords: Morphometric, clavicle, curvatures, circumference

Parametric investigation of a large two-stroke marine high-pressure direct injection engine by using computational fluid dynamics method

This study aims at the parametric investigation of the gas injection system settings of a large marine two-stroke dual fuel engine by using a developed and customized CFD method in the ANSYS Fluent software. The investigated engine injection system parameters include the gas injection timing, the gas injection duration, the gas injector lateral angle, and the gas injector holes number. Based on the comparison of the predicted performance parameters for the closed-cycle processes, the results indicate that the gas injector lateral angle is the most significant parameter that affects the engine power as well as the NO and CO2 emissions. For satisfying the contradictory objectives of retaining the engine power and reducing the NO and CO2 emissions, appropriate design settings for the gas injection are recommended for the investigated engine operation in the gas mode at 75% load.

Asymmetrical than symmetrical cerebral arterial bifurcations are more vulnerable to aneurysm presence

In order to investigate the role of lateral angle ratio (LA ratio) and daughter artery ratio (DA ratio) for predicting aneurysmal presence in main cerebral arterial bifurcations, three-dimensional cerebral angiographic data of major cerebral artery bifurcations were used for measurement of artery diameters and bifurcation angles including 115 middle cerebral arteries (MCAs), 59 basilar arteries (BAs), 35 internal carotid arteries (ICAs) and 115 anterior cerebral arteries (ACAs) with bifurcation aneurysms and control subjects of 1921 bifurcations with no aneurysms. The LA ratio (larger lateral angle/smaller lateral angle) and DA ratio (larger branch diameter/smaller branch diameter) were calculated, and ROC curve analysis of LA and DA ratios between normal and aneurysmal cases was performed. The LA and DA ratios of MCA bifurcations and the LA ratios of BA and ICA bifurcations with aneurysms were all significantly larger than normal bifurcations (P < 0.05), and the DA ratio of ACA bifurcations with aneurysms was significantly smaller than normal cases (P < 0.01). Moreover, the LA ratio or DA ratio between the normal and aneurysm cases in MCA, BA and ACA bifurcations demonstrated significant differences by ROC analysis (P < 0.01) except in the ICA bifurcations. No significant difference was observed (P > 0.05) between ruptured and unruptured aneurysms in MCA, BA, ICA and ACA bifurcations. In summary, normal MCA, BA and ICA bifurcations show symmetrical morphology in the lateral angles and daughter branches, whereas aneurysmal bifurcations show asymmetrical morphology. Normal ACA bifurcations have asymmetrical bilateral daughter branches while symmetrical branches are associated with ACA bifurcation aneurysm presence.

Asymmetrical middle cerebral artery bifurcations are more vulnerable to aneurysm formation

The objective of this study was to elucidate possible relationship between middle cerebral artery (MCA) bifurcation aneurysms and bifurcation morphology. In the present study, 799 patients with three-dimensional angiography were enrolled, including 115 patients with MCA bifurcation aneurysms and 684 subjects without aneurysms. The MCA bifurcation geometry, including angles formed between two M2 segments (φ1) and between M1 and M2 segments, vessel diameters and aneurysm sizes were measured. DA ratio (larger/smaller M2 in diameter) and LA ratio (larger/smaller lateral angle) were also analyzed. The LA and DA ratios and angle φ1 were significantly (P < 0.0001) greater in patients harboring MCA bifurcation aneurysms than in the control, whereas lateral angles and bifurcation branch diameters were significantly smaller (P < 0.01) in patients with than without bifurcation aneurysms. Angle φ1 was significantly increased (P < 0.0001) while both lateral angles significantly decreased (P < 0.0001 and P = 0.0005, respectively) with increase of patients’ age. The size of MCA bifurcation aneurysms was significantly (P < 0.05) positively correlated with the bifurcation vascular diameter and aneurysm neck at the MCA bifurcation. A significantly positive correlation existed between aneurysm neck and DA ratio (P = 0.0075), whereas an inverse correlation between aneurysm neck and LA ratio (P = 0.0219). MCA bifurcation aneurysms were mostly deviated toward the smaller lateral angles and smaller M2 branch. In conclusion, aneurysmal MCA bifurcations have asymmetrical bifurcation structures with widened bifurcation angles, narrowed lateral angles, decreased M1 diameter, imbalanced lateral angles and M2 segments, with the cutoff bifurcation angle of 125.0° and cutoff lateral angle ratio of 1.57 for predicting MCA bifurcation aneurysms, whereas normal MCA bifurcations show close to symmetrical structures in the lateral angles and M2 branches.