Declination Angle Research Articles

Association Between the Morphology of Proximal Tibiofibular Joint and the Presence of Knee OA.

Objective: The aim of this study was to evaluate the association between the morphology of the proximal tibiofibular joint (PTFJ) and the presence of knee osteoarthritis (OA).Methods: Twenty-eight OA subjects and 30 healthy subjects were enrolled in this study. A 3D model of the lower limb of each subject was constructed from CT scans and used to measure the characteristics of the PTFJ, including the shape of the articular facets, articular surface area, joint inclination, relative articular height, and joint declination. The association between the characteristics of the PTFJ and presence of knee OA was assessed using binomial logistic regression analysis.Results: There was a significant difference between the OA and healthy groups in terms of the inclination (p = 0.028) and declination (p = 0.020) of the PTFJ and relative articular height (p = 0.011). A greater inclination angle (OR: 1.463, 95% CI: 1.124–1.582, p = 0.021), greater declination angle (OR: 1.832, 95% CI: 1.691–2.187, p = 0.009), and lower relative articular height (OR: 0.951, 95% CI: 0.826–0.992, p = 0.008) were found to be associated with an increased likelihood of knee OA being present.Conclusion: The results of this study suggest that abnormal PTFJ morphology is associated with the presence of knee OA.

Mid-term Results of Subtalar Arthroereisis with Talar-Fit Implant in Pediatric Flexible Flatfoot and Identifying the Effects of Adjunctive Procedures and Risk Factors for Sinus Tarsi Pain.

ObjectivesTo (i) report the mid‐term outcomes of subtalar arthroereisis using Talar‐Fit implant for the treatment of flexible flatfoot patients; (ii) compare clinical and radiographic outcomes between arthroereisis with and without adjunctive operative procedures to investigate the effects of adjuncts on the outcomes; and (iii) analyze the risk factors associated with sinus tarsi pain, which is the most common postoperative complication of arthroereisis.MethodsThirty‐one flexible flatfoot children and adolescents (46 feet) treated with subtalar arthroereisis using Talar‐Fit implant from June 2014 to May 2019 were retrospectively analyzed. The feet were divided into four treatment groups: (i) arthroereisis alone, (ii) arthroereisis with gastrocnemius recession, (iii) arthroereisis with Kidner procedure, and (iv) arthroereisis with gastrocnemius recession and Kidner procedure. Clinical function was evaluated based on the American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot score. The following angles were measured for radiographic evaluation: talar‐first metatarsal angle, calcaneal pitch angle, and talar declination angle on the lateral view; and talar‐first metatarsal angle, talocalcaneal angle, and anteroposterior talonavicular coverage angle on the anteroposterior (AP) view. The paired Student's t‐test was used to compare the pre‐ and postoperative angular measurements and AOFAS scores. The Wilcoxon rank‐sum test was undertaken to determine the outcome differences among four treatment groups. Multivariate logistic regression analysis was used to analyze risk factors for sinus tarsi pain. P value <0.05 is considered statistically significant.ResultsThe mean follow‐up of the feet was 32.8 months (range, 10–71 months). The mean AOFAS score significantly improved from 55.5 ± 14.5 preoperatively to 86.3 ± 9.9 (P < 0.001). Comparison of radiographic outcomes showed that the lateral talar‐first metatarsal angle decreased by a mean of 19.1° ± 11.9° (P < 0.001), the calcaneal pitch angle increased by a mean of 5.4° ± 3.4° (P < 0.001), the talar declination angle decreased by a mean of 14.8° ± 9.9° (P < 0.001), the AP talar‐first metatarsal angle decreased by a mean of 15.6° ± 10.3° (P < 0.001), the AP talocalcaneal angle decreased by a mean of 7.2° ± 8.3° (P = 0.001), and the AP talonavicular coverage angle decreased by a mean of 20.4° ± 9.0° (P < 0.001). There were no statistically significant differences with regard to AOFAS score and all angle measurements on both the AP and lateral views among the four treatment groups. There was one dislocation case caused by a fall 6 weeks after surgery, which was treated nonoperatively. The incidence of sinus tarsi pain was 13% and logistic regression analysis indicated that patients with a longer distance from the tail end of the implant to the lateral calcaneal wall had 38.8% greater odds of developing sinus tarsi pain.ConclusionsThe mid‐term clinical and radiographic results were satisfactory in patients who underwent the subtalar arthroereisis procedure using Talar‐Fit implant, alone or in combination with other adjuncts, for the treatment of flexible flatfoot.

Effect of curvature on hyperspectral reflectance images of cereal seed-sized objects

Hyperspectral imaging for quality and safety inspection of agricultural products is frequently confronted with the challenge of handling rounded surfaces. This challenge is especially noted when the objects are as small as cereal grains for which curvature with respect to the spatial dimension of a pixel is large. Diffusely reflected light from regions near the edges of a uniformly illuminated object the size of a wheat kernel will have its intensity reduced greatly, historically modelled by the Lambert Cosine Law, eponymously named after Johann Lambert of the sixteenth century, who theorised that the fraction of energy reflected from a spot on a matte surface is related to the declination angle of the observer. The current study was performed to compare the predicted Lambertian response of reflected light to actual measurement on curved surfaces of mathematically definable shapes, namely cylinders and prolate ellipsoids, with the latter introduced as an approximation to a wheat kernel. Carbon black-doped and sintered PTFE (0.16–0.99 nominal reflectance) cylinders of three diameters, with the smallest on par with the minor dimension of a wheat kernel, were scanned using a benchtop hyperspectral imaging system, as were dull gray-painted prolate spheroids of equivalent size and white wheat kernels. The analysis consisted of comparing the measured reflectances (940–1650 nm) from individual pixels along the curved surface with those determined according to the Lambert Cosine Law. The findings indicate that central pixels responded well to correction, with a greater departure from theory for pixels closest to the edges. • Hyperspectral images can be improved by treating objects as more than flat surfaces. • With Lambertian behaviour assumed, wheat is corrected by prolate spheroids. • Reflectance correction is best in central regions and worst near the trailing edges.

Outcome of surgical management of plano-valgus foot in cerebral palsy with batchelor’s extra-articular subtalar arthrodesis

Introduction: Foot deformities caused by altered or abnormal muscle forces are common in patients with cerebral palsy. The incidence of foot deformities in cerebral palsy is approximately 70% to 90%. The most common deformity is ankle equinus, with equinovarus and equinovalgus deformities being equally common. A foot deformity can have significant effects on the patient's overall ambulatory level. The purpose of this study was to assess the functional outcome of batchelor’s extra-articular subtalar arthrodesis in spastic planovalgus foot in cerebral palsy children. Materials and Methods: This is a prospective study of 40 patients (68 feet) with spastic planovalgus foot deformity presenting to BIRRD (T) Hospital from October 2015 to October 2017. Children with spastic planovalgus foot between 6 yrs-14 yrs were included in study. There were 24 male and 16 female children. The mean age at the time of surgery was 10 yrs. Both feet were involved in 28 children, 8 had right foot involvement and 4 had left foot involvement. In our study we had 12 hemiplegics and 28 diplegics. Children with mental retardation, extra pyramidal type of cerebral palsy, rigid plano-valgus foot, spastic quadriplegia were excluded from the study. All patients underwent batchelor’s arthrodesis with fibular graft and were immobilized in below knee POP cast for 8 weeks. 24 patients underwent gastrosoleus lengthening along with batchelor’s arthrodesis. Clinical and functional outcome was assessed based on AOFAS (American orthopaedic foot and ankle score) clinical rating system. Radiological assessment was done by measuring Lateral talocalcaneal angle and Talar declination angle. The results of batchelor’s arthrodesis are stated as satisfactory and unsatisfactory. Satisfactory: Clinical and roentgenographic stabilization of the hind foot and no recurrence of planovalgus deformity. Unsatisfactory: Clinical and roentogenographic evidence of failure of stabilization. Results and Discussion: All children had spastic type of cerebral palsy. Post-operatively children were followed-up for an average period of 14 months, with range from 4 to 24 months. Among 40 patients (68 feet), 8 feet (12 percent) had residual valgus, 12 feet (18 percent) had graft absorption, 4 feet (6 percent) had fracture of the graft and none had varus deformity after an average follow-up of 14 months. Out of 68 feet, 44 feet had “satisfactory” result (65 percent) and 24 feet had “unsatisfactory” result (35 percent). Conclusion: Our experience concludes that batchelor’s extra-articular arthrodesis of sub-talar joint is a good procedure for correction of plano-valgus foot deformity in cerebral palsy patients. Advantages of the procedure are simplicity of the technique, immediate firm fixation and early weight bearing. Keywords: Cerebral palsy, Batchelor’s subtalar arthrodesis, Planovalgus foot, AOFAS clinical rating system.

Abrasive Water Jet Cutting of Hardox Steels—Quality Investigation

The paper aims to study the surface quality dependency on selected parameters of cuts made in Hardox™ by abrasive water jet (AWJ). The regression process was applied on measured data and the equations were prepared for both the Ra and Rz roughness parameters. One set of regression equations was prepared for the relationship of Ra and Rz on cutting parameters—pumping pressure, traverse speed, and abrasive mass flow rate. The second set of regression equations describes relationships between the declination angle in kerf as the independent variable and either the Ra or the Rz parameters as dependent variables. The models can be used to predict cutting variables to predict the surface quality parameters.

Narwhal Abundance in the Eastern Canadian High Arctic in 2013

In summer, narwhals (Monodon monoceros) migrate from Baffin Bay to northeastern Canada and northwest Greenland, where they are hunted by Inuit for subsistence. To prevent localized depletion, management of narwhals is based on summer stocks. The High Arctic Cetacean Survey (HACS), conducted in August 2013, was the first survey to estimate abundance of all 4 Canadian Baffin Bay narwhal summer stocks, as well as putative stocks in Jones Sound and Smith Sound, in the same summer. Narwhal abundance was estimated using a double-platform aerial survey. Distance sampling methods were used to estimate detection probability away from the track line. Mark-recapture methods were used to correct for the proportion of narwhals missed by visual observers on the track line (i.e., perception bias). We used a data-driven approach to identify single and duplicate sightings, using 4 covariates to compare differences in sightings made by front and rear observers based on: time of sighting, declination angle, group size, and species identity. Abundance in fjords was estimated using density surface modelling to account for their complex shape and uneven coverage. Estimates were corrected for availability bias (narwhals that are not available for detection because they are submerged when the aircraft passes overhead) using a new analysis of August dive behaviour data from narwhals equipped with satellite-linked time depth recorders. Corrected abundance estimates were 12,694 (95% CI: 6,324–25,481) for the Jones Sound stock; 16,360 (95% CI: 3,833–69,836) for the Smith Sound stock; 49,768 (95% CI: 32,945–75,182) for the Somerset Island stock; 35,043 (95% CI: 14,188–86,553) for the Admiralty Inlet stock; 10,489 (95% CI: 6,342–17,347) for the Eclipse Sound stock; and 17,555 (95% CI: 8,473–36,373) for the East Baffin Island stock. Total abundance for these 6 stocks was estimated at 141,908 (95% CI: 102,464–196,536). Sources of uncertainty arise from the high level of clustering observed, in particular in Admiralty Inlet, Eclipse Sound, and East Baffin Island, as well as the difficulty in identifying duplicate sightings between observers when large aggregations were encountered.

Surface declination governed asymmetric sessile droplet evaporation

The article reports droplet evaporation kinetics on inclined substrates. Comprehensive experimental and theoretical analyses of the droplet evaporation behaviour for different substrate declination, wettability and temperatures have been presented. Sessile droplets with substrate declination exhibit distorted shape and evaporate at different rates compared to droplets on the same horizontal substrate and is characterized by more often changes in regimes of evaporation. The slip stick and jump stick modes are prominent during evaporation. For droplets on inclined substrates, the evaporative flux is also asymmetric and governed by the initial contact angle dissimilarity. Due to smaller contact angle at the rear contact line, it is the zone of a higher evaporative flux. Particle image velocimetry shows the increased internal circulation velocity within the inclined droplets. Asymmetry in the evaporative flux leads to higher temperature gradients, which ultimately enhances the thermal Marangoni circulation near the rear of the droplet where the evaporative flux is highest. A model is adopted to predict the thermal Marangoni advection velocity, and good match is obtained. The declination angle and imposed thermal conditions interplay and lead to morphed evaporation kinetics than droplets on horizontal heated surfaces. Even weak movements of the TL alter the evaporation dynamics significantly, by changing the shape of the droplet from ideally elliptical to almost spherical cap, which ultimately reduces the evaporative flux. The life time of the droplet is modelled by modifying available models for non-heated substrate, to account for the shape asymmetry. The present findings may find strong implications towards microscale thermo-hydrodynamics.

Percutaneous hallux valgus surgery: Comparison between mini-invasive Chevron and Bosch osteotomies

Background and objectiveThrough percutaneous approaches, hallux valgus corrections can be performed with minimal soft tissue injury, postoperative pain, and good cosmetic results. Bosch osteotomy and MICA (Minimally Invasive Chevron Akin) have been shown to be effective techniques for the correction of hallux valgus, although there are currently no publications comparing percutaneous techniques with each other. The aim of this work is to compare the radiological and functional results of both techniques. Materials and methodsA retrospective, comparative study was carried out on patients with moderate hallux valgus. They were divided into 2 groups according to the percutaneous technique used: chevron osteotomy and Bosch osteotomy with screw fixation. The metatarsophalangeal, intermetatarsal, and distal articular veneer declination angles of the first metatarsal and the bone consolidation time were evaluated radiologically. The American Orthopaedic Foot and Ankle Surgery (AOFAS) scale was used for functional assessment. Complications were collected during the first year. ResultsThirty-eight patients in each group were included for the study. In each of the groups, the radiological angles were compared preoperatively and at the end of the follow-up, showing statistically significant changes in the 3 variables considered; but no differences were obtained by comparing them with each other. The time of consolidation was also similar in both groups. As for the AOFAS scale, an improvement was obtained with both techniques, but the difference was not significant when comparing them. ConclusionsBoth Bosch and MICA techniques showed comparable results at the end of the monitoring. Further work is needed to determine the advantages of each in the immediate postoperative period.

A Day at the Beach: Does the energy cost of walking influence visually perceived distance?

It takes less effort to walk from here to the Tiki Hut on the brick walkway than on the sandy beach. Does that influence how far away the Tiki Hut looks? Last year at VSS we ran the experiment to find out. The energy cost of walking on dry sand is twice that of walking on firm ground (Lejeune, et al., 1998). If distance is perceived in units of energetic cost or ‘behavioural potential’ (Proffitt, 2006), then visual distances over sand should be double those over brick. If distance is perceived in constant units (e.g. eye-heights as specified by declination angle; Ooi, et al., 2001), then the visual distances should be similar. Participants (N=13) viewed a target at a distance of 5, 7, 9, or 11m over sand or brick, were blindfolded and turned toward the same or different terrain, then blind-walked to match the visual distance. Walked Distance was analyzed using mixed effects regression with Target Distance, Viewed Terrain, and Walked Terrain as fixed-effect predictors. The energetic hypothesis predicts that walked distance should be greater after viewing over sand than over brick. But walked distance was actually shorter after viewing over sand (β = -0.59, SE = 0.21, χ2(1) = 6.05, p = 0.01). There was no difference between walked distance on sand and brick (p = 0.71), with moderate evidence for the null hypothesis (BFJZS = 3.38). Thus, perceived distance did not increase with the energy cost of the viewed terrain. Moreover, walked distance was no different on sand and brick, indicating an accurate locomotor calibration to each terrain. The results imply that distance is not perceived in terms of energetic cost. Rather, visually perceived distance is constant, and walking is guided by a visual-locomotor mapping (e.g. from declination angle to locomotor distance on the terrain) (Warren, 2019).

Magnification loupes influence on neck and trunk flexion of dental hygienists while scaling-A pilot study.

Work-related musculoskeletal disorders (MSDs) are common in the dental hygiene profession. Awkward postures contribute to MSDs and magnification loupes have been suggested to reduce this risk factor and minimize MSDs. After IRB approval, 24 hygienists were enrolled in the study: twelve hygienists wearing loupes with a standard manufacturer determined declination angle (control) and 12 hygienists wearing loupes with a custom measured declination angle (experimental). To measure changes in neck and trunk flexion, accelerometers were placed on the occipital region of head, cervical vertebrae C5, and thoracic vertebrae T5 and baseline posture was recorded. Typodonts with artificial calculus simulated the oral environment. Participants were randomly assigned to wear their designated loupes during the first or second trial of the experiment and scaled in each quadrant (UR, LR, UL, LL) of the mouth for two minutes. Participants completed the scaling task twice: in the loupes and no loupes condition in a counterbalanced order. Three-way mixed design ANOVA was used to determine posture differences in neck and trunk posture. Those wearing custom loupes (M=16.52, SD=6.40) had significantly less trunk flexion while scaling compared to hygienists wearing standard loupes (M=22.27, SD=6.40), F(1, 22)=7.14, P=.01. Neck flexion was not significantly affected while scaling between loupes vs no loupes or loupes type condition, (P's>.05). Posture was partially impacted by loupes type. Custom loupes resulted in less trunk flexion. Neck flexion was not affected by either loupes type.

Influence of Steel Structure on Machinability by Abrasive Water Jet.

Although the abrasive waterjet (AWJ) has been widely used for steel cutting for decades and there are hundreds of research papers or even books dealing with this technology, relatively little is known about the relation between the steel microstructure and the AWJ cutting efficiency. The steel microstructure can be significantly affected by heat treatment. Three different steel grades, carbon steel C45, micro-alloyed steel 37MnSi5 and low-alloy steel 30CrV9, were subjected to four different types of heat treatment: normalization annealing, soft annealing, quenching and quenching followed by tempering. Then, they were cut by an abrasive water jet, while identical cutting parameters were applied. The relations between the mechanical characteristics of heat-treated steels and the surface roughness parameters Ra, Rz and RSm were studied. A comparison of changes in the surface roughness parameters and Young modulus variation led to the conclusion that the modulus was not significantly responsible for the surface roughness. The changes of RSm did not prove any correlation to either the mechanical characteristics or the visible microstructure dimensions. The homogeneity of the steel microstructure appeared to be the most important factor for the cutting quality; the higher the difference in the hardness of the structural components in the inhomogeneous microstructure was, the higher were the roughness values. A more complex measurement and critical evaluation of the declination angle measurement compared to the surface roughness measurement are planned in future research.

Cirugía percutánea para hallux valgus: comparación entre osteotomía en chevron y de Bosch

Background and objectiveThrough percutaneous approaches, hallux valgus corrections can be performed with minimal soft tissue injury, less postoperative pain and good cosmetic results. Bosch osteotomy and MICA (Minimally Invasive Chevron Akin) have shown to be effective techniques for the correction of hallux valgus, although there are currently no publications comparing each other. The aim of this study is to compare the radiological and functional results of both techniques. Materials and methodsA retrospective, comparative study was carried out on patients with moderate hallux valgus. They were divided into two groups according to the percutaneous technique performed: Chevron osteotomy and Bosch osteotomy with screw fixation. The metatarsophalangeal, intermetatarsal, and distal articular veneer declination angles of the first metatarsal and the bone consolidation time were evaluated radiologically. The American Orthopaedic Foot and Ankle Surgery (AOFAS) score was used for functional assessment. Complications were registered during the first year. ResultsThirty-eight patients in each group were included for the study. In each of the groups, the radiological angles were compared preoperatively and at final follow-up, showing statistically significant changes in the three variables considered; but no differences were obtained by comparing them with each other. The time of consolidation was also similar in both groups. As for the AOFAS scale, an improvement was obtained with both techniques, but the difference was not significant when comparing them. ConclusionsBoth Bosch and MICA techniques showed comparable results at the end of the follow-up. Further work is needed to determine the advantages of each in the immediate postoperative time.

The Potential Impacts of the Erratic Motion of Dip Equator and Magnetic Poles

AbstractThis paper examined the secular displacement of the dip equator and the geomagnetic poles as well as the variations of the global magnetic inclination and declination angles using magnetometer measurements onboard different low‐Earth orbit (LEO) satellite. The secular variation of the dip equator and geomagnetic poles has different impacts on different applications—from affecting the long‐term characterization of the low‐latitude ionosphere to degrading the precision of geomagnetic navigation. The strong displacement of the dip equator can result in a systematic error in the determination of the long‐term equatorial electric field variations and hence in the characterization of ionospheric density structure, especially in the region, where the displacement of dip equator is large enough (more than 20 km or 0.2°/year) within the time scale of a solar cycle or less. Similarly, the slowly moving locations of magnetic poles, estimated from magnetometer observations onboard LEO satellite, exemplify noticeable discrepancy with that of world magnetic model (WMM) and International Geomagnetic Reference Field (IGRF) values, indicating inevitable possible impact on the precise geomagnetic navigation for commercial and military applications. Thus, accurately estimated locations of the dip equator and magnetic poles, as well as declination angles, are critically important.

Frictionally coupled sliding and spinning on an inclined plane

The frictionally coupled sliding and spinning of a disk on an inclined plane is considered. The main results of the paper are: (i) The exact solution of the problem can be obtained by quadratures (i.e. in terms of integrals). It includes the kinematical steepness S=σ(tanϕ)∕μ of the plane, with ϕ the declination angle, μ the kinetic friction coefficient, with σ=+1 for downward and σ=−1 for upward motion, respectively. (ii) The phenomenon of the simultaneous stopping of the two motions known from the case of horizontal plane (S=0) is only possible for −0.0804632≤S<1∕2. For example, the choice μ=0.3 leads to an upper bound of ϕmax=8.53o and ϕmax=1.38o for the downhill and uphill motions, respectively. (iii) In the range −0.0804632≤S<0 of the kinematical steepness dual solutions for the uphill motions exist. (iv) When the initial state coincides with one of the fixed points of the system (which only exist in the range −0.0804632≤S<1∕2), the exact solution reduces to a simple elementary form which describes the uniformly decelerated sliding and spinning of the disk until the simultaneous stopping of the two motions. This is a universal phenomenon in the sense that it occurs in all the frictionally coupled sliding and spinning motions considered to date in the literature.

Analysis of Magnetic Anomaly Characteristics of Underground Non-Coplanar Cross-buried Iron Pipelines

The non-coplanar cross-buried pipelines are a common way of pipeline wiring. In order to investigate the magnetic anomaly characteristics of the non-coplanar cross-buried pipelines and guide the site operation, the influences of a series of factors on the magnetic anomaly of the non-coplanar cross-buried pipelines are analyzed. Based on the principle of magnetic dipole construction, a forward model is established for the magnetic anomaly characteristics of the subsurface non-coplanar cross-buried pipelines. The basic characteristics of magnetic anomaly for the non-coplanar cross-buried pipelines are defined. The influences of geomagnetic parameters (geomagnetic intensity, geomagnetic inclination, and geomagnetic declination), pipeline parameters (thickness, magnetic susceptibility), and cross angle of pipelines on the characteristics of magnetic anomalies are analyzed. The results show that the shape of the total magnetic anomaly is mainly affected by the magnetic inclination, and the curve of magnetic anomaly at ± I site shows some symmetry. The amplitude is approximately linearly affected by the total geomagnetic field, magnetic declination, pipeline thickness, material magnetic susceptibility, and pipeline cross angle. There is a periodic change of the amplitude with the increase of geomagnetic inclination (−90°–&gt;90°). The crest-trough distance is mainly affected by geomagnetic inclination, magnetic declination, thickness, magnetic susceptibility, and pipeline cross angle. A more accurate measurement can be achieved if the direction of the pipelines is roughly measured and then the number of measurement points is augmented near the intersection of pipelines and the measurement lines. Present work obtains the equivalent magnetic dipole units by segmenting pipelines. The magnetic anomaly characteristics of non-coplanar crossed iron pipelines are successfully simulated. The numerical results are in accordance with the experimental analysis.

Identifying hazardous road sections using a fuzzy expert system

To identify hazardous sections of newly built mountainous highways, decision-makers require assistance to determine the sections that may pose risks to road users, thereby enhancing the level of road safety management and capital utilisation efficiency. In this research, traffic accident economic losses were used as evaluation indices to characterise 30 horizontally curved sections of roadways. These highway sections were divided into five levels based on their evaluated level of risk. With the effects of multiple factors and the characteristics of uncertainty, mathematical statistics and fuzzy expert systems (FESs) were used to determine the factors contributing to hazardous sections of mountainous highways. The membership functions and fuzzy rule base were decided according to accident data and expert experience and a method for identifying hazardous sections based on the expert systems was established. The risk values of another 35 horizontally curved sections were obtained by this method and good results were achieved using the method to identify hazardous sections. The results showed that hazardous section classification is greatly affected by the horizontal radius, grade and declination angle of the horizontal curve. The results obtained from the FESs agreed overall with actual accident data.

Morphometric analysis of the costal facet of the thoracic vertebrae.

Various studies have examined morphometric features of the vertebrae to understand the functional aspects of the spine. Geometric analysis of vertebral zygapophyseal facets has also been related to functional and clinical aspects of the spine, but no quantitative investigation of the costotransverse joint facet is found in the literature. The costal facet geometry may partly determine the mechanical interaction between the rib cage and spine for trunk stabilization during functional tasks and during breathing. Therefore, the present study proposes a method for estimating the 3D geometric features of the costal facets of the first 10 thoracic vertebrae (Th1-Th10). Series of landmarks (95 ± 43) were placed on 258 costal facets from a sample of 14 asymptomatic individuals to determine their 3D location and orientation. The relative location of the costal facet was used to investigate symmetry and asymmetry components of the overall vertebrae shape variation among thoracic levels using 3D geometric morphometric methods. Results showed significant variation in sagittal orientation (inclination angle) between levels with a gradual cephalic orientation in the lower levels. No significant difference was observed on transverse orientation (declination angle). The shape of the costal facet was flatter at Th1 and from Th5 to Th10 and more concave from Th2 to Th4. An average difference of 7° between right and left facet orientation in both sagittal and transverse plane was demonstrated. Asymmetry of costal facet relative location was also detected and significantly influenced by the thoracic level. Nevertheless, location and orientation of the costal facets seem to be independent features of vertebrae morphology.

Design and Sensitivity Analysis of Hybrid Photovoltaic-Fuel-Cell-Battery System to Supply a Small Community at Saudi NEOM City

This research paper aimed to design and present a sensitivity analysis of a hybrid photovoltaic-fuel-cell-battery (PV/FC/B) system to supply a small community for the recently planned grand city NEOM in Saudi Arabia. The location of the city of NEOM is characterized by a high average level of solar irradiance. The average daily horizontal solar radiation is around 5.85 kWh/m2. A detailed feasibility and techno-economic evaluation of a PV/FC/B hybrid energy system were done to supply a daily load demand of 500 kWh (peak-35 kW). The PV array was the main source to meet the load demand. During the surplus periods, the battery was charged using extra energy and powered the electrolyzer for hydrogen production. The produced hydrogen was stored for later use. During the deficit periods, the FC and/or battery supported the PV array to meet the load demand. Two benchmarks, the cost of energy (COE) and net present cost (NPC), were used to identify the best size of the PV/FC/B system. Variation of the tilt angle of the PV array and the derating factor were considered to determine the effect of the performance of the PV/FC/B system’s COE and NPC. The main findings confirmed that a 200 kW PV array, 40 kW FC, 96 batteries, 50 kW converter, 110 kW electrolyzer, and 50 kg hydrogen tank was the best option to supply the load demand. The values of total NPC and COE were $500,823 and $0.126/kWh. The annual excess energy was very sensitive to the declination angle of the PV array. The minimum annual excess energy was achieved at an angle of 30 degrees. It decreased by 75.7% and by 60.6% compared to a horizontal surface and 50 degrees of declination, respectively. To prove the viability of the proposed system, a comparison with grid extension along with a diesel generation system was carried out.

Statistical Analysis of Equatorial Plasma Irregularities Retrieved From Swarm 2013–2019 Observations

AbstractIn this study, we present a statistical analysis of equatorial plasma irregularities (EPIs) by using in situ plasma density measurements of the Swarm constellation from December 2013 to December 2019. The occurrence patterns for both postsunset and postmidnight EPIs with respect to longitude, season, local time, latitude, solar activity, and geomagnetic activity level are investigated. The main findings are as follows: (1) The postsunset/postmidnight EPIs occurrence rates exhibit different longitudinal and seasonal dependence: The postsunset EPIs have the maximum occurrence rate over the American‐Atlantic sectors during the December solstice and equinoxes, and the postmidnight EPIs have the maximum occurrence rate during the June solstice, especially over the African sector. (2) The postsunset EPIs occurrence rates have a positive correlation with solar activity, while the postmidnight EPIs are negatively correlated with it. (3) The latitudinal distribution of EPIs exhibits a double‐peak structure around ±5° magnetic latitude with a more significant peak in the summer hemisphere. (4) The EPIs occurrence rate increases with increasing geomagnetic activity level. (5) The main controlling factors for the distribution of postsunset EPIs are the magnetic declination angle, equatorial vertical E × B drift, and thermospheric zonal wind. For the postmidnight EPIs, the main controlling factors are likely to be atmospheric gravity waves and equatorward thermospheric meridional wind associated with midnight temperature maximum.

Analysis of Plasma Bubble Signatures in Total Electron Content Maps of the Low-Latitude Ionosphere: A Simplified Methodology

The ionosphere over the Brazilian region has particular characteristics due to the large geomagnetic declination angle over most of the territory. Furthermore, the equatorial ionization anomaly southern crest is located over the Brazilian territory. In this region, plasma irregularities may arise in the post-sunset hours. These ionospheric irregularities develop in the form of magnetic field-aligned plasma depletions, known as equatorial plasma bubbles, which may seriously affect radio signals that propagate through them. These irregularity structures can cause amplitude and phase scintillation of the propagating signals, thereby compromising the availability, performance, and integrity of satellite-based communication and navigation systems. Additionally, the total electron content (TEC) introduces propagation delays that can contribute to range measurement errors for global positioning system (GPS) users. The ionospheric characteristics change significantly according to the time of day, season, as well as the solar and geomagnetic activities, among other factors. Indeed, the ionosphere is one of the most significant sources of errors in the positioning and navigation systems based on the GPS satellites. Due to these features, there is a strong interest by the scientific community in better understanding and characterizing the ionospheric behavior. In this context, the TEC analysis has wide applicability for space plasma studies and is a well-established tool for investigating the ionospheric behavior and its potential impact on space-based navigation systems. One of the goals of these studies is the generation of TEC maps for a geographic region based on GPS observations. In the present work, some electrodynamic processes of the low-latitude ionosphere are reviewed and the TEC estimation based on GPS measurements is revisited in detail. A methodology aimed at creating the TEC maps is presented and validated by comparison with results from other geophysical instruments, such as all-sky imagers and ionosondes. Finally, examples of the ionospheric behavior displayed by TEC maps during equatorial plasma bubble events and a geomagnetic storm are fully described and discussed.