Footprint Region Research Articles

Robot-assisted transosseous repair of triangular fibrocartilage complex: a cadaver study.

The feasibility and accuracy of robot-assisted bone tunnel construction in the transosseous repair of the triangular fibrocartilaginous complex (TFCC) were compared with those of freehand arthroscopic repair. A total of 20 cadaveric specimens were randomized into robotic-assisted and arthroscopy-guided groups. Three bone tunnels were constructed in the ulnar foveal region in each specimen. The discrepancy between the planned and actual tunnel exits was determined in the robot-assisted group by merging images. The success rate of tunnel construction, time consumption and number of drilling attempts were compared between groups. The median planned/actual exit discrepancy was 0.8 mm in the robot-assisted group, with 90% of tunnel exits successfully placed in the footprint region, compared to 63.3% in the arthroscopy-guided group. The robot-assisted group spent less time and required fewer drilling attempts to construct bone tunnels. These results indicated that the robot-assisted technique can accurately construct multiple bone tunnels in the foveal region and reduce the difficulty of TFCC transosseous repair.Level of evidence: III.

Numerical analysis of the tread grooves' acoustic resonances for the investigation of tyre noise

Abstract Tyre/road noise is one of the major sources of noise pollution in urban areas. This phenomenon can be described as the combined effect of several generation and amplification mechanisms. Acoustic resonances due to the tread grooves at the footprint region, also known as pipe resonances, are particularly important since they can generate high noise levels if they combine with harmonic generation mechanisms. This paper deals with a numerical investigation of this phenomenon and describes modelling approaches that might be used to estimate the frequencies and the mode shapes of these resonances.

The impact of high-quality development on ecological footprint: An empirical research based on STIRPAT model

It is urgent to coordinate the development of economy and environment under the “dual carbon” goal. As China's new development stage and mode, high-quality development takes into account both the speed and quality of economic, providing the possibility of achieving a “win-win” situation for the economy and the environment. In order to test the practical impact of high-quality development on ecological, based on the STIRPAT model, this paper introduces high-quality development index instead of per capita GDP, so as to measure the current economic situation in China, and explore the relationship between high-quality development and ecological footprint, and demonstrates the feasibility from theory and practice. At the same time, it pays attention to the complex effects of population and technology on environmental quality. The results show that the contradiction between economy and ecology still exists in China. The ecological footprint index of 30 provinces in the past 21 years has increased as a whole, and the fworst ecological footprint has concentrated in the Yellow River basin. But since 2012, the growth of the footprint has slowed. The slow down time and low value region of ecological footprint were observed, and it was found that they overlapped with the proposed time and the high value area of high-quality development. The level of high-quality development in China has also continued to rise, with regional differences but gradually narrowing. Among them, green development and shared development contribute more to the improvement of high-quality development level. Compared with the traditional economic development mode, high-quality development can reduce the increase of ecological footprint, and the longer the time, the smaller the increase, more conducive to long-term sustainable development. In addition, population and technology factors are also profoundly affecting China's ecological pattern. The increase in population size and population density, as well as the increase in the proportion of coal-based energy consumption structure, will lead to increased environmental pressure. The improvement of population quality and the reduction of energy consumption intensity will help alleviate ecological pressure. The research is helpful to provide policy guidance and path combination reference for China's sustainable development, and also provide new ideas for the global coordination of the relationship between economy and environment.

The Emergence of Non-Energy Uses of Coal and the Future of Lignite Mining in a Region of Low Carbon Footprint, a Case Study

Abstract The rapid development of renewable energy sources, which has been going on for the last two decades, allows now the elimination of the coal use for power generation. Nevertheless, coal will continue to be used in key-industrial sectors, such as steel and cement production, which are crucial for maintaining the living standards of modern society. The future remains doubtful for coals of poor quality characteristics, such as lignite, which is used almost exclusively for power generation purposes. The present study aims to show that, even in the case of lignite, the transition to a zero-carbon economy must be decoupled from the mines closure. In this context, a combined SWOT–AHP analysis was conducted in order to compare seven potential non-energy uses of the lignite produced in the mines of Western Macedonia region, based on six criteria that are in line with the framework set by the European Union for the selection of the best technologies for every site-specific case. This comparison showed that the most promising technologies are related to the production of organic fertilizers and soil amendments, raw materials and products for the construction industry, activated carbon, and graphene. These technologies may contribute to the achievement of socioeconomic and environmental targets that are critical for the just transition of Western Macedonia region to a new, sustainable productive model.

Quantitative Magnetic Resonance Imaging-Based Tendon Healing of Different Regions of the Shoulder: Comparison Between the Suture-Bridge and Single-Row Techniques.

Rotator cuff retears occur more often at the proximal region with the suture-bridge (SB) technique than at the typical footprint region with the single-row (SR) technique. Few longitudinal clinical trials have focused on the postoperative tendon quality of the repaired rotator cuff at different regions between the 2 techniques. To compare tendon healing of the proximal and distal regions between the SB and SR techniques. Cohort study; Level of evidence, 3. Included were consecutive patients who underwent arthroscopic rotator cuff repair and undertook clinical and magnetic resonance imaging (MRI) examinations at 3, 6, and 12 months postoperatively between 2016 and 2017. These patients were divided into the SB and SR groups according to the technique used. The repaired tendon was segmented into distal and proximal regions on ultrashort echo time-T2* mapping images. Clinical outcomes (Constant score, American Shoulder and Elbow Surgeons score, Fudan University Shoulder Score, and visual analog scale for pain) and MRI-based tendon healing (T2* values) of different regions were compared between the 2 groups. The differences in T2* values and clinical scores were determined by 1-way analysis of variance for repeated measurements. A total of 31 patients (17 in SB group and 14 in SR group) were included. At 12-month follow-up, significant improvements from preoperatively were achieved for all patients in all clinical scores (P < .001 for all). No significant between-group differences were found in T2* values of the distal region at any time point; however, the mean T2* value of the proximal region at 3 months was significantly higher in the SB group compared with the SR group (P = .03). This difference became nonsignificant at subsequent follow-up time points. Significant clinical improvements over time can be expected in the first year after arthroscopic rotator cuff repair. In the early postoperative period, higher T2* values in the proximal region of the repaired tendon (representing inferior tendon quality) were seen with the SB technique compared with the SR technique; however, this phenomenon was resolved over time.

In vivo evaluation of rotator cuff internal impingement during scapular plane abduction in asymptomatic individuals.

Internal impingement-or entrapment of the undersurface of the rotator cuff tendon against the glenoid during overhead activities-is believed to contribute to articular-sided tears. However, little is known about internal impingement outside athletic populations. Therefore, the objectives of this study were to (1) describe glenoid-to-footprint distances and proximity centers during dynamic, in vivo motion in asymptomatic individuals, and(2) determine the extent to which these measures differed between individuals with and without a rotator cuff tear. Shoulder kinematics were assessed in 37 asymptomatic individuals during scapular plane abduction using a high-speed biplane radiographic system. Glenoid-to-footprint distances and proximity center locations were calculated by combining the kinematics withcomputerized tomography-derived bone models. Glenoid-to-footprint contact was presumed to occur when the minimum distance was less than the estimated labral thickness. The condition of the supraspinatus tendon (intact, torn) was assessed using ultrasound. Minimum distances and proximity centers were compared over humerothoracic elevation angles (90°, 110°, 130°, 150°) and between supraspinatus pathology groups using two-factor mixed model analysis of variances. Glenoid-to-footprint minimum distances decreased consistently across elevation angles (p < 0.01) without a significant difference between groups. Contact was estimated to occur in all participants. Proximity centerswere generally located on the anterior half of the rotator cuff footprint and on the posterosuperior glenoid. Statement of Clinical Significance: Internal impingement during overhead motions may be a prevalent mechanism of rotator cuff pathology as contact appears to be common and involves the region of the rotator cuff footprint where degenerative rotator cuff tears are thought to originate.

English

BACKGROUND Haemophilic patients are more prone to obesity, due to physical inactivity which is a predisposing factor for structural and functional deformities. In obese people, long term loading has negative impact on lower limb and foot, which causes deformities like flat-foot. In foot, the primary component responsible for absorption and dissipation of forces is medial longitudinal arch and in flat-foot this arch is collapsed. Flat-foot causes pain and discomfort during weight bearing activities. In Haemophilic patients, obesity and flat-foot lead to further postural complications. As no study has been conducted on this topic before, we decided to study on this. The objectives of this study were to assess obesity, flat-foot and co relate obesity and flat-foot in Haemophilic adolescents. METHODS Height and weight of participants were measured to calculate BMI. Total 36 participants were chosen for this study. The subjects were assessed for flat-foot by using Staheli’s Plantar Arch Index. Footprints were taken to calculate the plantar index. The Staheli’s Plantar Arch Index was measured by dividing the width of central region by width of heel region on footprint, which was calculated as: a line tangent to the medial edge of forefoot and heel region, then a perpendicular line was drawn medially to laterally from mid - point of tangent line in central region of footprint (A) and similarly another perpendicular was drawn from heel region (B). The plantar index was then calculated by dividing value A with value B. RESULTS Flat-foot was seen in 25 % population having BMI between 33 - 35. Our data also suggested that age affects the medial arch of foot, the elder population showed increased percentage of flat-foot than the younger group. Individuals with type A haemophilia had increased percentage of flat-foot when compared with type B haemophiliacs, as type A haemophilia is considered severe type. CONCLUSIONS The results show that there is high prevalence of flat-foot in haemophilic patients, this requires rehabilitation and can help prevent further complications. KEY WORDS Haemophilia, Obesity, Flat-foot

Agriculture and animal husbandry increased carbon footprint on the Qinghai-Tibet Plateau during past three decades

Agriculture and animal husbandry are important sources of greenhouse gas (GHG) emission and contribute to climate change, but the carbon sink function of cropland and grassland plays an important role in mitigating climate changes. Based on ecological footprint methodology, this study comprehensively considered carbon emission and carbon sequestration in order to calculate the carbon footprints from agriculture and animal husbandry, and analyzed spatiotemporal distribution of carbon emission, carbon sequestration, and carbon footprint on the QTP. The results showed that during the period of 1990–2015, the carbon emissions of agriculture and animal husbandry on the QTP increased by 163% and 41%, respectively. Agricultural carbon sequestration showed an increasing trend with a growth rate of 45%, and animal husbandry carbon sequestration showed that it increased by 40% in the period of 1990–2005 and then decreased by 28% in the period of 2005–2015. The carbon footprint of agriculture reduced by 23% from 1990 to 1995, then grew by 112% from 1995 to 2015, and the animal husbandry carbon footprint reduced by 18% from 1990 to 2005 then grew by 71% from 2005 to 2015; both of these phenomena showed the downward trends first before trending upward. The high carbon emission and sequestration regions of agriculture were mainly distributed in the southeastern and northwestern areas of the QTP, and the high carbon footprint regions of agriculture were centered in the southeastern and northeastern areas. The high carbon emission regions of animal husbandry were located in southeastern areas, while the high carbon sequestration regions were in the southeastern, southwestern and middle areas. Additionally, the high carbon footprint regions were in southwestern areas. All measures mentioned showed a significant variation in spatial distribution. The economic and population growth contributed to the increase in carbon footprint despite technological advances. This study propose options to reduce the carbon emission and suggestions to improve carbon sink function. This study provides an important basis for policy formulation and planning for sustainable agriculture on the QTP.

Using land-based stations for air–sea interaction studies

In situ measurements representing the marine atmosphere and air–sea interaction are taken at ships, buoys, stationary moorings and land-based towers, where each observation platform has structural restrictions. Air–sea fluxes are often small, and due to the limitations of the sensors, several corrections are applied. Land-based towers are convenient for long-term observations, but one critical aspect is the representativeness of marine conditions. Hence, a careful analysis of the sites and the data is necessary. Based on the concept of flux footprint, we suggest defining flux data from land-based marine micrometeorological sites in categories depending on the type of land influence: 1. CAT1: Marine data representing open sea, 2. CAT2: Disturbed wave field resulting in physical properties different from open sea conditions and heterogeneity of water properties in the footprint region, and 3. CAT3: Mixed land–sea footprint, very heterogeneous conditions and possible active carbon production/consumption. Characterization of data would be beneficial for combined analyses using several sites in coastal and marginal seas and evaluation/comparison of properties and dynamics. Aerosol fluxes are a useful contribution to characterizing a marine micrometeorological field station; for most conditions, they change sign between land and sea sectors. Measured fluxes from the land-based marine station Östergarnsholm are used as an example of a land-based marine site to evaluate the categories and to present an example of differences between open sea and coastal conditions. At the Östergarnsholm site the surface drag is larger for CAT2 and CAT3 than for CAT1 when wind speed is below 10 m/s. The heat and humidity fluxes show a distinctive distinguished seasonal cycle; latent heat flux is larger for CAT2 and CAT3 compared to CAT1. The flux of carbon dioxide is large from the coastal and land–sea sectors, showing a large seasonal cycle and significant variability (compared to the open sea sector). Aerosol fluxes are partly dominated by sea spray emissions comparable to those observed at other open sea conditions.

Amphipathic molecules modulate PIEZO1 activity.

PIEZO proteins are large eukaryotic mechanically-gated channels that function as homotrimers. The basic PIEZO1 structure has been elucidated by CryoEM and it assembles into a protein-lipid dome. A curved lipid region allows for the transition to the lipid bilayer from the dome (footprint). Gating PIEZO1 is mediated by bilayer tension that induces an area change in the lipid dome. The footprint region is thought to be energetically important for changes in lateral tension. Amphipathic molecules can modulate channel function beyond the intrinsic gating properties of PIEZO1. As a result, molecules that modify lipid properties within the lipid-channel complex (footprint and dome) will profoundly affect channel kinetics. In this review, we summarize the effects some amphipathic molecules have on the lipid bilayer and PIEZO1 function. PIEZO1 has three states, closed, open and inactivated and amphipathic molecules influence these transitions. The amphipathic peptide, GsMTx4, inhibits the closed to open transition. While saturated fatty acids also prevent PIEZO1 gating, the effect is mediated by stiffening the lipids, presumably in both the dome and footprint region. Polyunsaturated fatty acids can increase disorder within the lipid-protein complex affecting channel kinetics. PIEZO1 can also form higher-ordered structures that confers new kinetic properties associated with clustered channels. Cholesterol-rich domains house PIEZO1 channels, and depletion of cholesterol causes a breakdown of those domains with changes to channel kinetics and channel diffusion. These examples underscore the complex effects lipophilic molecules can have on the PIEZO1 lipid dome structure and thus on the mechanical response of the cell.

The coordinated action of PPR4 and EMB2654 on each intron half mediates trans-splicing of rps12 transcripts in plant chloroplasts.

The pentatricopeptide repeat proteins PPR4 and EMB2654 have been shown to be required for the trans-splicing of plastid rps12 transcripts in Zea mays (maize) and Arabidopsis, respectively, but their roles in this process are not well understood. We investigated the functions of the Arabidopsis and Oryza sativa (rice) orthologs of PPR4, designated AtPPR4 (At5g04810) and OsPPR4 (Os4g58780). Arabidopsis atppr4 and rice osppr4 mutants are embryo-lethal and seedling-lethal 3weeks after germination, respectively, showing that PPR4 is essential in the development of both dicot and monocot plants. Artificial microRNA-mediated mutants of AtPPR4 displayed a specific defect in rps12 trans-splicing, with pale-green, yellowish or albino phenotypes, according to the degree of knock-down of AtPPR4 expression. Comparison of RNA footprints in atppr4 and emb2654 mutants showed a similar concordant loss of extensive footprints at the 3' end of intron 1a and at the 5' end of intron 1b in both cases. EMB2654 is known to bind within the footprint region in intron 1a and we show that AtPPR4 binds to the footprint region in intron 1b, via its PPR motifs. Binding of both PPR4 and EMB2654 is essential to juxtapose the two intron halves and to maintain the RNAs in a splicing-competent structure for the efficient trans-splicing of rps12 intron 1, which is crucial for chloroplast biogenesis and plant development. The similarity of EMB2654 and PPR4 orthologs and their respective binding sites across land plant phylogeny indicates that their coordinate function in rps12 trans-splicing has probably been conserved for 500million years.

Land cover and its transformation in the backward trajectory footprint region of the Amazon Tall Tower Observatory

Abstract. The Amazon rain forest experiences the combined pressures from human-made deforestation and progressing climate change, causing severe and potentially disruptive perturbations of the ecosystem's integrity and stability. To intensify research on critical aspects of Amazonian biosphere–atmosphere exchange, the Amazon Tall Tower Observatory (ATTO) has been established in the central Amazon Basin. Here we present a multi-year analysis of backward trajectories to derive an effective footprint region of the observatory, which spans large parts of the particularly vulnerable eastern basin. Further, we characterize geospatial properties of the footprint regions, such as climatic conditions, distribution of ecoregions, land cover categories, deforestation dynamics, agricultural expansion, fire regimes, infrastructural development, protected areas, and future deforestation scenarios. This study is meant to be a resource and reference work, helping to embed the ATTO observations into the larger context of human-caused transformations of Amazonia. We conclude that the chances to observe an unperturbed rain forest–atmosphere exchange at the ATTO site will likely decrease in the future, whereas the atmospheric signals from human-made and climate-change-related forest perturbations will increase in frequency and intensity.

CLIPick: a sensitive peak caller for expression-based deconvolution of HITS-CLIP signals

High-throughput sequencing of RNAs isolated by crosslinking immunoprecipitation (HITS-CLIP, also called CLIP-Seq) has been used to map global RNA–protein interactions. However, a critical caveat of HITS-CLIP results is that they contain non-linear background noise—different extent of non-specific interactions caused by individual transcript abundance—that has been inconsiderately normalized, resulting in sacrifice of sensitivity. To properly deconvolute RNA–protein interactions, we have implemented CLIPick, a flexible peak calling pipeline for analyzing HITS-CLIP data, which statistically determines the signal-to-noise ratio for each transcript based on the expression-dependent background simulation. Comprising of streamlined Python modules with an easy-to-use standalone graphical user interface, CLIPick robustly identifies significant peaks and quantitatively defines footprint regions within which RNA–protein interactions were occurred. CLIPick outperforms other peak callers in accuracy and sensitivity, selecting the largest number of peaks particularly in lowly expressed transcripts where such marginal signals are hard to discriminate. Specifically, the application of CLIPick to Argonaute (Ago) HITS-CLIP data were sensitive enough to uncover extended features of microRNA target sites, and these sites were experimentally validated. CLIPick enables to resolve critical interactions in a wide spectrum of transcript levels and extends the scope of HITS-CLIP analysis. CLIPick is available at: http://clip.korea.ac.kr/clipick/

Double-Layer Rotator Cuff Repair: Anatomic Reconstruction of the Superior Capsule and Rotator Cuff Improves Biomechanical Properties in Repairs of Delaminated Rotator Cuff Tears

Background: Delamination in rotator cuff tears has been identified as a prognostic factor for negative outcome after repair, with a reported prevalence between 38% and 88%. Purpose: To compare biomechanical properties of 3 repair techniques for delaminated rotator cuff tears. Study Design: Controlled laboratory study. Methods: Eighteen fresh-frozen cadaveric shoulders were used to evaluate rotator cuff footprint reconstruction, contact area and pressure, displacement under cyclical loading, and load to failure of 3 double-row repair configurations: double-row suture repair with medial row knots (medially knotted bridge, mkB); knotless double-row repair using suture tapes (knotless bridge, klB); and knotless double-row, double-layer-specific repair (double-layer, DL). Dynamic pressure sensors were used to assess contact patterns at the footprint region in 0°, 30°, and 60° of glenohumeral abduction and 5 rotational positions (0°, 30° of internal rotation, 30° of external rotation, 60° of internal rotation, 60° of external rotation). Optical markers were used to document whole tendon and individual layer displacement after rotator cuff repair under cyclical loading for 200 cycles (10 N to 100 N at 1 Hz). Specimens were then loaded monotonically to failure at a rate of 33 mm/min. Results: Mean contact area and footprint restoration were highest in the DL group at 60° of glenohumeral abduction for all rotational positions (mkB mean ± SD, 195.4 ± 54.3 mm2, 66.7% ± 19.7%; klB, 250.6 ± 34.9 mm2, 76.2% ± 10.3%; DL, 318.4 ± 36.6 mm2, 109.1% ± 24.0%; P < .001). The double-layer-specific repair showed the least displacement under cyclical loading (mkB mean ± SD, 0.53 ± 0.18 mm; klB, 0.79 ± 0.37 mm; DL, 0.31 ± 0.24 mm; P = .029), most closely resembling the native tendon. Peak loads at failure were comparable between repair groups (mkB mean ± SD, 366.92 ± 70.59 N; klB, 280.05 ± 77.66 N; DL, 398.35 ± 109.04 N; P = .083). Conclusion: Anatomic restoration of the superior capsular and tendon insertion in delaminated rotator cuff tears with a double-layer-specific repair configuration demonstrated superior footprint restoration with increasing abduction, while providing construct displacement comparable to the native tendon under cyclical loading. Peak load at failure was comparable between repair constructs. Clinical Relevance: The prevalence and clinical importance of delaminated rotator cuff tears have long been underestimated. Anatomically correct individual reconstruction of the superior capsule and rotator cuff could restore near-native biomechanics and potentially reduce the risk of rotator cuff repair failure.

Rewilding the world's largecarnivores.

Earth's terrestrial large carnivores form a highly endangered group of species with unique conservation challenges. The majority of these species have experienced major geographical range contractions, which puts many of them at high risk of extinction or of becoming ecologically ineffective. As a result of these range contractions and the associated loss of intact predator guilds, the ecological effects of these species are now far less widespread and common, with inevitable consequences for ecosystem function. Rewilding—which includes reintroducing species into portions of their former ranges—is an important carnivore conservation tool and means for restoring top-down ecological regulation. We conducted a global analysis of potential reintroduction areas. We first considered protected areas where one or more large carnivore species have been extirpated, identifying a total of 130 protected areas that may be most suitable for carnivore reintroduction. These protected areas include sites in every major world region, and are most commonly found in Mongolia (n = 13), Canada (n = 11), Thailand (n = 9), Namibia (n = 6), Indonesia (n = 6) and Australia (n = 6). We considered the sizes of protected areas, their levels of protection, the extent of human impacts within and around the protected areas, and the status of prey species in the protected areas. Finally, we used the ‘last of the wild’ approach to identify contiguous low human footprint regions within the former ranges of each species, identifying an additional 150 areas which could be the focus of conservation efforts to create conditions conducive to reintroductions. These low footprint regions were most commonly found in the USA (n = 14), Russia (n = 14), Canada (n = 10), China (n = 9) and Mauritania (n = 8). Together, our results show the global-scale potential for carnivore rewilding projects to both conserve these species and provide critical ecological and social benefits.

Avoiding tibia physeal injury during double-bundle posterior cruciate ligament reconstruction

BackgroundAnatomic studies of the paediatric posterior cruciate ligament (PCL) demonstrate that the tibial attachment spans the epiphysis, physis and metaphysis. To better reproduce the anatomy of the PCL and avoid direct physeal injury, a double-bundle PCL reconstruction technique that includes both an all-epiphysial and an all-metaphyseal tibial tunnel has been proposed. The purpose of this study was to evaluate tibial tunnel placement in a paediatric double-bundle PCL reconstruction technique that avoids direct physeal injury using a 3-D computer model.MethodsTen skeletally immature cadaveric knee specimens (ages 5–11) were used to create 3-D model reconstructions from CT scans. All-metaphyseal and all-epiphysial tibial tunnels were simulated with the goal of maintaining adequate spacing (≥2 mm) between the tibial physis and tunnels to avoid injury. The all-metaphyseal tunnel, simulated at sizes of 5, 6 and 7 mm, entered anteriorly, below the tibial tubercle (apophysis) and exited posteriorly in the metaphyseal PCL footprint, distal to the proximal tibial physis. Four-millimetre all-epiphysial proximal tibial tunnels were simulated to enter the epiphysis anteromedially and exit posteriorly at the central epiphysial region of the PCL footprint, proximal to the physis. The distance was measured from the all-metaphyseal tunnels to the physis posteriorly and from the all-epiphysial tunnels to the physis, both anteriorly and posteriorly.ResultsIn all specimens, the 4 mm all-epiphysial tunnel and the 5, 6 and 7 mm all-metaphyseal tunnels maintained adequate spacing, ≥2 mm from the physis. In the specimens aged 5–7 years, the 5, 6 and 7 mm all-metaphyseal tunnels measured a mean distance of 3.5, 2.8 and 2.5 mm from the physis, respectively. In the specimens aged 8–11 years, the 5, 6 and 7 mm all-metaphyseal tunnels measured a mean distance of 3.4, 2.9 and 2.6 mm from the physis. In the specimens aged 5–7 years, the all-epiphysial tunnel measured a mean of 2.1 mm to the physis anteriorly and a mean of 2.8 mm posteriorly. In the specimens aged 8–11 years, the all-epiphysial tunnel measured a mean of 2.2 mm to the physis anteriorly and 2.4 mm posteriorly.ConclusionThese computer-aided 3-D models of paediatric knees illustrate that 5, 6 and 7 mm all-metaphyseal tunnels as well as 4 mm all-epiphysial tunnels can be placed without direct injury to the proximal tibial physis. The margin of error for direct physeal injury is small, especially for the all-epiphysial tunnel. Further, the all-epiphysial tunnel, while reproducing the anatomy of the PCL epiphysial attachment, may also produce a more extreme ‘killer turn’ of the graft. Modifications to the all-epiphysial tunnel may be considered to reduce the impact of the high ‘killer turn’ angle on the tibia.Level of evidenceIV.

Three-Dimensional CT Evaluation of Tunnel Positioning in ACL Reconstruction Using the Single Anteromedial Bundle Biological Augmentation (SAMBBA) Technique.

Background:Remnant preservation may confer important advantages in the anterior cruciate ligament (ACL)–reconstructed knee. However, the presence of a large remnant may obscure visualization and impair the ability to correctly place tunnels during surgery.Purpose:To determine whether tunnel placement during anatomic ACL reconstruction using the single anteromedial bundle biological augmentation (SAMBBA) technique is consistent and precise when a large native remnant is preserved.Study Design:Case series; Level of evidence, 4.Methods:Included in this study were 99 patients undergoing an ACL reconstruction during which at least 50% of the native ACL was preserved. The femoral tunnel was created using an outside-in specific guide. The tibial tunnel was positioned in the anteromedial region of the ACL footprint, and the remnant was carefully preserved while drilling and passing the semitendinosus graft through it. Postoperatively, 3-dimensional computed tomography (3D CT) was used to evaluate tunnel placement. The mean tunnel locations were calculated and the standard deviation was used to evaluate precision of positioning. Inter- and intrareader agreement were determined to assess reliability of evaluation of tunnel position.Results:The center of the femoral tunnel was positioned at a mean 19.4% (SD, 2%) of the depth of the notch and a mean 23.1% (SD, 3.5%) of the lateral wall height. The center of the tibial tunnel was positioned at a mean 36.3% (SD, 3.8%) of the anteroposterior length of the tibial plateau and at a mean 47.0% (SD, 2.7%) of the mediolateral width. The small standard deviations demonstrate that this technique allows precise tunnel placement. The tunnel positions achieved were consistent with previous anatomic studies of femoral and tibial anteromedial bundle insertion. Intra- and interobserver reliability were high.Conclusion:Three-dimensional CT evaluation demonstrated that despite the presence of a large remnant, placement of femoral and tibial tunnels for anatomic ACL reconstruction using the SAMBBA technique is consistent and precise.

Insights into aerosol chemistry during the 2015 China Victory Day parade: results from simultaneous measurements at ground level and 260 m in Beijing

Abstract. Strict emission controls were implemented in Beijing and adjacent provinces to ensure good air quality during the 2015 China Victory Day parade. Here, we conducted synchronous measurements of submicron aerosols (PM1) at ground level and 260 m on a meteorological tower by using a high-resolution aerosol mass spectrometer and an aerosol chemical speciation monitor, respectively, in Beijing from 22 August to 30 September. Our results showed that the average PM1 concentrations are 19.3 and 14.8 µg m−3 at ground level and 260 m, respectively, during the control period (20 August–3 September), which are 57 and 50 % lower than those after the control period (4–30 September). Organic aerosols (OAs) dominated PM1 during the control period at both ground level and 260 m (55 and 53 %, respectively), while their contribution showed substantial decreases (∼ 40 %) associated with an increase in secondary inorganic aerosols (SIAs) after the parade, indicating a larger impact of emission controls on SIA than OA. Positive matrix factorization of OA further illustrated that primary OA (POA) showed similar decreases as secondary OA (SOA) at both ground level (40 % vs. 42 %) and 260 m (35 % vs. 36 %). However, we also observed significant changes in SOA composition at ground level. While the more oxidized SOA showed a large decrease by 75 %, the less oxidized SOA was comparable during (5.6 µg m−3) and after the control periods (6.5 µg m−3). Our results demonstrated that the changes in meteorological conditions and PM loadings have affected SOA formation mechanisms, and the photochemical production of fresh SOA was more important during the control period. By isolating the influences of meteorological conditions and footprint regions in polluted episodes, we found that regional emission controls on average reduced PM levels by 44–45 %, and the reductions were close among SIA, SOA and POA at 260 m, whereas primary species showed relatively more reductions (55–67 %) than secondary aerosol species (33–44 %) at ground level.

Cortical Bony Thickening of the Lateral Intercondylar Wall: The Functional Attachment of the Anterior Cruciate Ligament

Background: The anatomy of the anterior cruciate ligament (ACL) has become the subject of much debate. There has been extensive study into attachment points of the native ligament, especially regarding the femoral attachment. Some of these studies have suggested that fibers in the ACL are of differing functional importance. Fibers with higher functional importance would be expected to exert larger mechanical stress on the bone. According to Wolff’s law, cortical thickening would be expected in these areas. Purpose: To examine cortical thickening in the region of the ACL footprint (ie, the functional footprint of the ACL). Study Design: Descriptive laboratory study. Methods: Using micro–computed tomography with resolutions ranging from 71 to 91 μm, the cortical thickness of the lateral wall of the intercondylar notch in 17 cadaveric knees was examined, along with surface topography. After image processing, the relationship between the cortical thickening and surface topology was visually compared. Results: A pattern of cortical thickening consistent with the functional footprint of the ACL was found. On average, this area was 3 times thicker than the surrounding bone and significantly thicker than the remaining lateral wall (P < .0001). This thickening was roughly elliptical in shape (with a mean centroid at 23.5 h:31 t on a Bernard and Hertel grid) and had areas higher on the wall where greater thickness was present. The relationship to previously reported osseous landmarks was variable, although the patterns were broadly consistent with those reported in previous studies describing direct and indirect fibers of the ACL. Conclusion: The findings of this study are consistent with those of recent studies describing fibers in the ACL of differing functional importance. The area in which the thickening was found has been defined and is likely to represent the functional footprint of the ACL. Clinical Relevance: This information is of value to surgeons when determining the optimal place to position the femoral attachment site of the reconstructed ACL.

A numerical study on the friction and wear predictions of finger lock chuck in landing gear

Locking mechanism is an important part of landing gear, which is required to lock retractable landing gear during taking off and landing processes of aircraft. This paper introduces an effective numerical simulation forecasting method to investigate the friction and wear of unworn finger lock chuck, where an associated experiment was conducted to verify the correctness of the method. The dynamic explicit procedure was adopted in the simulation process with Abaqus/Explicit solver, the user subroutine VFRIC integrated in the commercial package ABAQUS was coded to study the rate-dependent dynamic friction coefficient during the movement of unworn finger lock chuck. The friction simulation results indicate that large deformation occurs in the finger lock chuck during the unlocking–locking process and the maximum stress lies in the root zone of finger lock chuck, the difference of axial acting force between simulation results and experiment results of unworn finger lock is small. From the perspective of frictional energy dissipation, nodal frictional energy density rate within contact footprint regions was taken as the index to assess the wear severity. Python language commands were programmed to realize the secondary development of ABAQUS post-process, the nodal frictional energy density rate distribution in contact footprint regions of finger lock chuck was graphically displayed. The wear simulation results show that the nodal frictional energy density rate distribution of finger lock chuck concentrates significantly at the regions of two rounded corners in the raised portion of chuck and inner side surface of the raised platform, indicating that wear first occurs in these regions after the unworn finger lock chuck is put into use. The wear simulation results obtained was compared with a worn finger lock chuck after 500 times disengagement-stuck processing wear test, and the results are basically accordant.