Assessment of novel electrophysiology simulator-a survey study.

BACKGROUND: Invasive electrophysiology (EP) training requires intellectual skills related to the interpretation of intracardiac electrograms. The classic approach to the education of young electrophysiologists focused solely on theoretical knowledge and overseen procedures in patients as no real-life-like simulation of EP studies was available. OBJECTIVE: The purpose of this study was to assess a novel tool for EP training based on fully interactive, online simulator providing real clinical experience to the users. METHODS: EP simulator users access a system with simulated electrocardiogram, mimicking signals recorded by a catheter. Assessment of EP simulator by 40 electrophysiologists from 16 countries was collected via online questionnaire. RESULTS: The realism of ECG signals was described as excellent or very good by 90% of responders, of intracardial signals by 82.5%. Realism of signal interactions and user experience was judged as excellent or very good by 75% and 70% accordingly. One hundred percent of users agree definitely or mostly that EP Simulator helps to translate theoretical into practical knowledge. Of responders, 97.5% would include it in EP training programs as it is extremely or very useful for training purposes in the opinion of 87.5%. Of responders, 72.5% think that training on EP simulator can potentially reduce the rate of complications. In 87.5%, the overall experience was completely or mostly satisfying and would be recommended by 100% of responders. CONCLUSION: EP simulator is a feasible tool for training of young electrophysiologist, and it may be potentially included in the cardiologist curriculum. We should particularly emphasize the positive respondents' assessment of EP simulator overall realism.

Bus Violence: An Open Benchmark for Video Violence Detection on Public Transport.

The automatic detection of violent actions in public places through video analysis is difficult because the employed Artificial Intelligence-based techniques often suffer from generalization problems. Indeed, these algorithms hinge on large quantities of annotated data and usually experience a drastic drop in performance when used in scenarios never seen during the supervised learning phase. In this paper, we introduce and publicly release the Bus Violence benchmark, the first large-scale collection of video clips for violence detection on public transport, where some actors simulated violent actions inside a moving bus in changing conditions, such as the background or light. Moreover, we conduct a performance analysis of several state-of-the-art video violence detectors pre-trained with general violence detection databases on this newly established use case. The achieved moderate performances reveal the difficulties in generalizing from these popular methods, indicating the need to have this new collection of labeled data, beneficial for specializing them in this new scenario.

Effect of concentric vs. eccentric variant of lower limbs plyometric training on biomechanical and biochemical parameters.

AbstractThe study aimed to compare the effectiveness of two variants of 4 weeks plyometric training involving jumping up (dominance of concentric muscle work, UP) and jumping down (dominance of eccentric muscle work, DOWN) the stairs. Twenty-six young men were divided into two groups: UP (n = 13) and DOWN (n = 13). Control measurements of the muscle torques, vertical jumps, and creatine kinase (CK) activity were performed every week. The training resulted in significant changes (p < 0.001) in the muscle torques of the hip extensors (Δ ≈ 20% in both groups) and plantar flexors (ΔUP = 25%, ΔDOWN = 33%), but in the muscle torques of the knee extensors a significant (p < 0.001) increase occurred only in the group jumping down the stairs (ΔDOWN ≈ 15%). Furthermore, a significant increase (p < 0.001) of the height of the vertical jump was noted in the study only in the group jumping down (ΔDOWN = 8%). Training with the dominance of eccentric work caused greater weekly changes in the activity of creatine kinase in the plasma. The study confirmed that the exercise involving jumping on the stairs is viable in plyometric training, as it is an effective means of training the strength of the muscles of the lower limbs and vertical jump height, with a greater share assigned to jumping down consecutive steps.

Application of Crowd Simulations in the Evaluation of Tracking Algorithms.

Tracking and action-recognition algorithms are currently widely used in video surveillance, monitoring urban activities and in many other areas. Their development highly relies on benchmarking scenarios, which enable reliable evaluations/improvements of their efficiencies. Presently, benchmarking methods for tracking and action-recognition algorithms rely on manual annotation of video databases, prone to human errors, limited in size and time-consuming. Here, using gained experiences, an alternative benchmarking solution is presented, which employs methods and tools obtained from the computer-game domain to create simulated video data with automatic annotations. Presented approach highly outperforms existing solutions in the size of the data and variety of annotations possible to create. With proposed system, a potential user can generate a sequence of random images involving different times of day, weather conditions, and scenes for use in tracking evaluation. In the design of the proposed tool, the concept of crowd simulation is used and developed. The system is validated by comparisons to existing methods.

Application of high field magnetic resonance microimaging in polymer gel dosimetry.

PURPOSE: The purpose of this work was to examine the suitability of VIPARnd polymer gel-9.4 T magnetic resonance microimaging system for high spatial resolution dose distribution measurements. METHODS: The VIPARnd samples (3 cm in outside diameter and 12 cm in height) were exposed to ionizing radiation by using a linear accelerator (Varian TrueBeam, USA; 6 MV x-ray beam). In the calibration stage, nine gel dosimeter vials were irradiated in a water phantom homogenously to the doses from 1.5 to 30 Gy in order to obtain R2-dose relation. In the verification stage, two gel dosimeter vials were irradiated in the half beam penumbra area of 10 × 10 cm radiation field using the amount of monitor units appropriate to deliver 20 Gy at the field center. The gels were imaged on a vertical 9.4 T magnetic resonance (MR) microimaging scanner using single slice and multislice (9 slices) multiecho (90 × 7 ms) sequences at the spatial resolutions of 0.2-0.4 × 0.2-0.4 × 3 mm3 and 0.2-0.4 × 0.2-0.4 × 1 mm3 respectively. The gels were subjected to microimaging during the period of two weeks after irradiation. The reference data consisted of the dose profiles measured using the diode dosimetry, radiochromic film, ionization chamber, and the water phantom system. RESULTS: The VIPARnd -9.4 T MR microimaging system was characterized by the dose sensitivity of 0.067 ± 0.002 Gy-1  s-1 at day 3 after irradiation. The dose resolution at 10 Gy (at P = 95%) was equal to 0.42 Gy at day 3 after irradiation using a single slice sequence (0.2 × 0.2 × 3 mm3 ) and 2.0 Gy at day 4 after irradiation using a multislice sequence (0.2 × 0.2 × 1 mm3 ) for one signal acquisition (measurement time: 15 min). These values were improved by ~1.4-fold when using four signal acquisitions in the single slice sequence, and by ~2.78-fold for 12 signal acquisitions in the multislice sequence. Furthermore, decreasing the in-plane resolution from 0.2 × 0.2 mm2 to 0.4 × 0.4 mm2 resulted in a dose resolution of 0.3 Gy and 1 Gy at 10 Gy (at P = 95%) for one signal acquisition in the single slice and multislice sequences respectively (measurement time: 7.5 min). As reveals from the gamma index analysis the dose distributions measured at days 3-4 postirradiation using both VIPARnd verification phantoms agree with the data obtained using a silicon diode, assuming 1 mm/5% criterion. A good interphantom reproducibility of the polymer gel dosimetry was proved by monitoring of two phantoms up to 10 days after irradiation. However, the agreement between the dose distributions measured using the diode and polymer gel started to get worse from day 5 after irradiation. CONCLUSION: The VIPARnd -9.4T MR microimaging system allows to obtain dose resolution of 0.42 Gy at 10 Gy (at P = 95%) for a spatial resolution of 0.2 × 0.2 × 3 mm3 (acquisition time: 15 min). Further studies are required to improve a temporal stability of the gel-derived dose distribution.

Effect of a strength or hypertrophy training protocol, each performed using two different modes of resistance, on biomechanical, biochemical and anthropometric parameters.

The study aimed to analyse the effectiveness of two variants of 8-week strength training (hypertrophy, strength) with different modes of resistance. Healthy male subjects (n=75) were allocated to five groups of equal size: hypertrophy training with a variable cam (Hyp-Cam), hypertrophy training with disc plates (Hyp-Disc), maximal strength training with a variable cam (Str-Cam), maximal strength training with disc plates (Str-Disc), and a control group (CG). The Hyp-Cam and Str-Cam groups trained with a machine where the load was adjusted to the strength capabilities of the elbow flexors. The Hyp-Disc and Str-Disc groups trained on a separate machine in which a load was applied with disc plates. The CG did not train. All groups were assessed for changes and differences in one-repetition (1RM) lifts, isokinetic muscle torque, arm circumference and arm skinfold thickness, and plasma creatine kinase (CK) activity. Within the 8-week training period the 1RM increased (p<.001) in all groups by over 20%, without significant between-group differences. Muscle torque increased significantly (p<.001) only in the Hyp-Cam group (by 13.7%). Arm circumference at rest increased by 1.7 cm (p<.001) and 1.1 cm (p<.001) in the Hyp-Cam and Hyp-Disc groups, respectively, but not in the Str-Cam (0.3 cm; p>.05) or Str-Disc (0.2 cm; p>.05) group. Skinfold thickness of the biceps and triceps decreased more within the 8-week period in Str-Cam (by 1.1 and 2.1 cm; p<.001 and p<.001 respectively) and Str-Disc (0.7 and 1.5 cm; p<.001 and p<.01 respectively) than in Hyp-Cam (by 0.4 and 1.8 cm; p>.05 and p<.01 respectively) and Hyp-Disc groups (by 0.2 and 1.4 cm; p>.05 and p<.05 respectively). CK activity was significantly (p<.05) elevated in each training group except Hyp-Cam (p>.05). The 8-week hypertrophy training with a variable cam results in greater peak muscle torque improvement than in the other examined protocols, with an insignificant increase in training-induced muscle damage indices.

Improvement of Fast Model-Based Acceleration of Parameter Look-Locker T1 Mapping.

Quantitative mapping is desirable in many scientific and clinical magneric resonance imaging (MRI) applications. Recent inverse recovery-look locker sequence enables single-shot T1 mapping with a time of a few seconds but the main computational load is directed into offline reconstruction, which can take from several minutes up to few hours. In this study we proposed improvement of model-based approach for T1-mapping by introduction of two steps fitting procedure. We provided analysis of further reduction of k-space data, which lead us to decrease of computational time and perform simulation of multi-slice development. The region of interest (ROI) analysis of human brain measurements with two different initial models shows that the differences between mean values with respect to a reference approach are in white matter-0.3% and 1.1%, grey matter-0.4% and 1.78% and cerebrospinal fluid-2.8% and 11.1% respectively. With further improvements we were able to decrease the time of computational of single slice to 6.5 min and 23.5 min for different initial models, which has been already not achieved by any other algorithm. In result we obtained an accelerated novel method of model-based image reconstruction in which single iteration can be performed within few seconds on home computer.

Biomechanical conditions of maintaining balance in snowboarding.

Snowboarding, along with Alpine skiing, is one of two most popular winter sports. While there are many studies on the mechanical conditions of movement in skiing, there is a lack of studies analyzing the forces affecting snowboarders. The difference in body orientation between snowboarding and skiing means that applying the same biomechanical rules to both sports is unjustified and a separate analysis is needed. The most difficult aspect of snowboarding is maintaining the correct body balance which is dependent on the directions and magnitudes of external forces and their torques. Therefore, the aim of this study was to analyze the forces that affect a snowboarder on the slope and the effects of these forces on the maintenance of a stable body posture. The research method used in the work is based on the theoretical analysis of physical phenomena that occur during riding on the snowboard. The study describes the biomechanical conditions that allow the snowboarder to maintain an upright posture when standing and moving, as well as the forces that initiate movement and decelerate the snowboarder. The physical forces that appear when moving forward and along an arc are analyzed, as are the mechanical interdependences that enable effective snowboarding. Knowing the rules of forces action is the best method for understanding how a snowboarder move and keep the balance on a slope. The application of theoretical knowledge should improve not only the self-confidence and effectiveness of the snowboarders but also the safety of their riding.

Detection of new potentially pathogenic mutations in two patients with primary pigmented nodular adrenocortical disease (PPNAD) - case reports with literature review.

INTRODUCTION: Primary pigmented nodular adrenocortical disease (PPNAD) is a rare form of ACTH-independent Cushing's syndrome (CS). Half of patients with PPNAD are sporadic cases and the other half familial. MATERIAL AND METHODS: We present two patients with PPNAD confirmed by genetic analysis. RESULTS: In both patients there were no abnormal findings on diagnostic imaging of both adrenals and heart. Patients underwent bilateral two-stage adrenalectomy. Histopathological examination confirmed PPNAD. Genetic testing showed the following mutations in the PRKAR1A gene coding for the regulatory subunit type 1A of the protein kinase A enzyme: c.125dupG (patient 1) and c.15dupT (patient 2). Both these defects lead to inactivation of the PRKAR1A protein and are consequently causative of PPNAD in these patients. CONCLUSIONS: The novel mutations presented in this article are considered to be pathogenic for PPNAD.

Quality Control Procedure Based on Partitioning of NMR Time Series.

The quality of the magnetic resonance spectroscopy (MRS) depends on the stability of magnetic resonance (MR) system performance and optimal hardware functioning, which ensure adequate levels of signal-to-noise ratios (SNR) as well as good spectral resolution and minimal artifacts in the spectral data. MRS quality control (QC) protocols and methodologies are based on phantom measurements that are repeated regularly. In this work, a signal partitioning algorithm based on a dynamic programming (DP) method for QC assessment of the spectral data is described. The proposed algorithm allows detection of the change points-the abrupt variations in the time series data. The proposed QC method was tested using the simulated and real phantom data. Simulated data were randomly generated time series distorted by white noise. The real data were taken from the phantom quality control studies of the MRS scanner collected for four and a half years and analyzed by LCModel software. Along with the proposed algorithm, performance of various literature methods was evaluated for the predefined number of change points based on the error values calculated by subtracting the mean values calculated for the periods between the change-points from the original data points. The time series were checked using external software, a set of external methods and the proposed tool, and the obtained results were comparable. The application of dynamic programming in the analysis of the phantom MRS data is a novel approach to QC. The obtained results confirm that the presented change-point-detection tool can be used either for independent analysis of MRS time series (or any other) or as a part of quality control.

Comparison of changes in the load components for intense training on two machines: with a variable-cam and with a disc plate.

BACKGROUND: The object of the presented experiment was to construct a cam to provide the optimal load while training the muscles throughout the entire range of motion of a joint. The starting point for our consideration was the flexion of the elbow joint - based on its functioning, we wished to verify the efficacy of the cam during various workout routines. METHODS: The experiment was two-fold. In the first part, muscle flexion torque values were measured for 78 male participants, under static conditions and at four different angles of the elbow joint. Subsequently, the data was analyzed and based on the resulting graph the shape of a cam was determined. In the next stage, 75 men underwent training using two types of machines designed to exercise the elbow joint's flexors, one with a mounted cam and one with a disc plate. RESULTS: The strength and power changes were found to be more pronounced in the workouts conducted with the cam-equipped machine. CONCLUSIONS: Our conclusion stemming from this project is that a cam, designed specifically to customize and optimize the external load to the muscle strength potential during training, results in a safer, more efficient in terms of promoting the desired training effect and a more comfortable workout.

Evaluation of the effectiveness of training on a machine with a variable-cam.

The aim of the study was to assess the effectiveness of the training of elbow flexors through the use of 2 machines, one of which was equipped with a disc plate of constant radius, the other one with a variable-cam having a radius adjustable to muscle strength. The experiment included 45 men divided into 3 equal groups: training group A (variable-cam), training group B (circle), and control group C. The training lasted for 8 weeks, 3 times a week. In order to control the effects, the values of peak torque and power of the flexor muscles of the elbow were isokinetically measured for the angular velocities of 30°/s and 60°/s. Also taken were anthropometric measurements of the arm and the creatine kinase (CK) activity in the blood plasma. As a result of the training, significant increases of biomechanical values were noted only in group A: power increased over 20%, the peak torque over 14%. After the training, significant increases of arm circumference in the relaxed position were noted in group A (17 mm), as well as in group B (11 mm). Also, some changes in CK activity were observed between Monday and Friday in a training week. On the basis of the experimental measurements, it may be ascertained that training elbow flexor muscles on a machine with a variable-cam is more efficient for increases in strength and power, as well as for some anthropometric parameters, than training on a machine with a disc plate.

Evaluation of muscular stabilization ability during a static workout.

The aim of this research was to determine the moving and stabilizing functions of selected groups of muscles during the process of static workout. 15 students of the Academy of Physical Education were tested in non-competitive training. Muscular torques achieved during flexing and extending big limb joints were used as the determinant of force. Comparative analysis of torque values achieved in passive stabilization (with support) and muscular stabilization (without support) in elbow and knee joints was carried out. The value of the force applied to the passively stabilizing element in a given measurement during the flexion of elbow and the extension of knee joint was tested. The results of these tests allowed us to learn the value of muscular torques and - after statistical analysis - the relationship between them in particular functions.