The hip radiographic magnification correlates with patient’s BMI

Objective. Obese patients have a higher prevalence of total hip arthroplasty (THA) and they are likely to experience a higher rate of pre-operative and post-operative complications. Pre-operative templating is a standard method of THA planning aiming to minimize the risk of complications. The accuracy of pre-operative templating depends on the knowledge of radiographic magnification factor. Whether and to what extent obesity affects radiographic magnification is not well described in literature. The purpose of this study was to determine whether obesity type affects hip radiographic magnification and quantify the relationship between the obesity measured and change in radiographic magnification. Materials and Methods. Digital radiographs of 303 patients who underwent THA were taken from clinical archives. The size of implanted femoral head was taken as an internal calibration marker to estimate hip radiographic magnification. Patients were stratified into obesity categories by body mass index (BMI). Patients’ mass, BMI, and body surface area (BSA) were studied as predictors of hip magnification. Results. There is a significant effect of obesity type on hip radiographic magnification (one-way ANOVA, p<0.001). The radiographic magnification correlates with patients’ mass (r=0.443, p<0.001), BMI (r=0.450, p<0.001) and BSA (r=0.443, p<0.001). For every 17 kg increase in patients’ mass, 5 kg/m2 increase in the BMI and for every 0.27 m2 in the BSA there is a 1 percent increase in the hip radiographic magnification. The increase in hip radiographic magnification with mass, BMI, and BSA is higher in females than in males. Conclusion. BMI could be used to estimate the increase in hip radiographic magnification due to obesity by adding 1% of magnification on average for each subsequent BMI category.

Generative Facial Prior for Large-Factor Blind Face Super-Resolution

Most existing face super-resolution (SR) methods are developed based on an assumption that the degradation is fixed and known (e.g., bicubic down sampling). However, these methods suffer a severe performance drop in various unknown degradations in real-world applications. Previous methods usually rely on facial priors, such as facial geometry prior or reference prior, to restore realistic face details. Nevertheless, low-quality inputs cannot provide accurate geometric priors while high-quality references are often unavailable, which limits the use of face super-resolution in real-world scenes. In this work, we propose GPLSR which used the rich priors encapsulated in the pre-trained face GAN network to perform blind face super-resolution. This generative facial priori is introduced into the face super-resolution process through channel squeeze-and-excitation spatial feature transformation layer (SE-SFT), which makes our method achieve a good balance between realness and fidelity. Moreover, GPLSR can restores facial details with single forward pass because of powerful generative facial prior information. Extensive experiment shows that when the magnification factor is 16, this method achieves better performance than existing techniques in both synthetic and real datasets.

Evaluation and Comparison of Self-Made and Commercial Calibration Markers for Radiographic Magnification Correction in Veterinary Digital Radiography

Introduction Magnification error is always present in radiography and calibration is necessary, if high accuracy is required in pre-surgical planning. The goal of this study was to verify the use of self-made markers and calibration techniques and to establish guidelines for magnification correction. Methods We evaluated and compared spherical and linear markers of different sizes with focus on practicability, accuracy and precision. Markers were placed on foam pads or attached to flexible arms. Results Vertical marker deviation of 1 cm from the anatomical reference point corresponded to ∼1% of magnification error in our setting. Marker placement along the horizontal plane showed no significant magnification in the periphery of the radiograph. All markers showed good accuracy and the commercial spherical marker with a flexible segment arm had the best results regarding practicability. Discussion Our study suggests that marker type is not solely responsible for usability and accuracy but also the type of fixation. In the absence of a calibration marker, calculation of the magnification factor using a measurement tape during radiography is equally reliable. Use of a fixed averaged calculated calibration factor showed poor agreement compared with the marker calibration, probably due to variability in size of the animals. In conclusion, if precision matters, use of a calibration marker, which could be purchased or self-made, is advised.

Food web on ice: a pragmatic approach to investigate the trophic magnification of chemicals of concern

Background The trophic magnification factor (TMF) is a metric that describes the average trophic magnification of a chemical through a food web. TMFs may be used for the risk assessment of chemicals, although TMFs for single compounds can vary considerably between studies despite thorough guidance available in the literature to eliminate potential sources of error. The practical realization of a TMF investigation is quite complex and often only a few chemicals can be investigated due to low sample masses. This study evaluated whether a pragmatic approach involving the large-scale cryogenic sample preparation practices of the German Environmental Specimen Bank (ESB) is feasible. This approach could provide sufficient sample masses for a reduced set of samples allowing screenings for a broad spectrum of substances and by that enabling a systematic comparison of derived TMFs. Furthermore, it was assessed whether plausible TMFs can be derived with the ‘Food web on ice’ approach via a comparison with literature TMF values. Results This investigation at Lake Templin near Potsdam is the first TMF study for a German freshwater ecosystem and aimed to derive TMFs that are appropriate for regulatory purposes. A set of 15 composite biota samples was obtained and analyzed for an extended set of benchmark chemicals such as persistent organic pollutants, mercury and perfluoroalkyl substances. TMFs were calculated for all substances that were present in > 80% of the biota samples. For example, in the case of polychlorinated biphenyls, TMFs from 1.7 to 2.5 were determined and comparisons to literature TMFs determined in other freshwater ecosystems showed similarities. We showed that 32 out of 35 compounds analyzed had TMFs significantly above 1. In the remaining three cases, the correlations were not statistically significant. Conclusions The derived food web samples allow for an on-demand analysis and are ready-to-use for additional investigations. Since substances with non-lipophilic accumulation properties were also included in the list of analyzed substances, we conclude that the ‘Food web on ice’ provides samples which could be used to characterize the trophic magnification potential of substances with unknown bioaccumulation properties in the future which in return could be compared directly to the benchmarking patterns provided here.

Study of the Vernier Effect Based on the Fabry–Perot Interferometer: Methodology and Application

The optical Vernier effect is a powerful tool for improving the sensitivity of an optical sensor, which relies on the use of two sensor units with slightly detuned frequencies. However, an improper amount of detuning can easily cause the Vernier effect to be unusable. In this work, the effective generation range of the Vernier effect and the corresponding interferometer configuration are suggested and experimentally demonstrated through a tunable cascaded Fabry–Perot interferometer structure. We further demonstrate a practical method to increase the magnification factor of the Vernier effect based on the device bandwidth. Only the optical path length of an interferometer probe and the sensitivity of the measurement parameters are needed to design this practical interferometer based on the Vernier effect. Our results provide potential insights for the sensing applications of the Vernier effect.

Levels of selected pesticides and trophic transfer of DDTs through the aquatic food web in the Lake Ziway ecosystem

The levels of 27 selected pesticides and trophic biomagnification of DDT were investigated in biota samples of the Lake Ziway in the Rift valley region, Ethiopia. Pesticide residues were analyzed using gas chromatography coupled with mass spectrometry (GC MS). Carbon source and trophic position were calculated by using 13C and 15N stable isotopes, individually, and trophic magnification factors (TMFs) were inferred. Among pesticides analyzed, only DDT and its metabolites (o,pʹ-DDD, o,pʹ-DDE, p,pʹ-DDD, and p,pʹ-DDE) were quantified in biota samples. The most prominent metabolite was p,pʹ-DDE with mean concentration ranging from the 0.22-7.7ngg− 1 wet weight. Moreover, the ratio of DDT/DDD + DDE in all the biota samples was less than 1 signifying historical DDT application. The trophic magnification factor (TMF) for p,pʹ-DDE, and ΣDDT were 1.18 and 1.19 respectively. Regression of log [ΣDDT] vs TL (trophic level) among all biota species showed a significant correlation, indicating that DDTs are biomagnifying along with the food web of Lake Ziway. The concentrations of DDTs and other organochlorine pesticides found in biota from Lake Ziway were, in general, lower than studies found in previous studies carried out in the same lake.

Experimental study on an overhead crane passing a rail track joint

Purpose. To confirm the theoretical conclusions that determining the load from the wheel impact with the joint of rails in the metal structures of overhead cranes used in the technological processes at ore mining and processing mills and integrated works and moving along the rail tracks requires that the dynamic magnification factor should take into account the trolley position. Methodology. To assess the load to which the crane metal structures are exposed the electric strain measurement method using direct bridge circuit was chosen. To calibrate the strain measurement system, the direct method was used, under which calibration is performed directly on the structure on which experimental studies will be carried out in the future. Findings. It was established that the dynamic magnification factor in the metal structure of the overhead crane had the following values when passing the last rail joints: 1.54 (with the trolley in the middle of the bridge), 2.46 (with the trolley at 0.25 of the crane span from the end beam), 3.33 (with the trolley in the extreme position). So, with the trolley being at a distance of 0.25 of the crane span from the end beam, the dynamic magnification factor is 74%, and with the trolley in the middle of the bridge, it is 46% of the dynamic magnification factor if the trolley is in its extreme position. Originality. The scientific novelty consists in the first experimental confirmation of the results obtained in the theoretical studies on the overhead crane passing the joints of the rail track with regard to the crane trolley position, which leads to changes in the stiffness of the main beam in the interval between the trolley and the final beam. Practical value. The results obtained enable calculations on the crane bridge metal structure during the design and repair of the main and end beams taking into account the value of the dynamic magnification factor, which allows increasing the reliability and durability of the crane metal structure as a whole.

Numerical simulation of transient processes in propeller shaft straining under ice loads

Object and purpose of research. The object of the research is the shaftline of an icebreaker and ice-going vessels, the purpose is to develop an algorithm for determining the loads for calculating the strength of the shafts of icebreakers and icegoing vessels under ice loads in a nonlinear dynamic setting and determining the dynamic magnification factor. Materials and methods. The study is based on finite element method (FEM). Main results. As a result of numerical analysis, the magnification factors of ice loads acting on the propeller shaft when vessel moves in an ice field up to 4 m thick are investigated. Conclusion. The research results can be used to calculate the fatigue strength of the icebreakers and ice-going vessels shaftlines.