Center Of Gravity Coordinates Research Articles

Optimized Target Delineation Procedure for the Radiosurgery Treatment of Ventricular Tachycardia: Observer-Independent Accuracy

Stereotactic body radiotherapy (SBRT) has shown promising results for patients with recurrent ventricular tachycardia that failed catheter ablation. The simplest method of target delineation based on manual transfer of CTV from several 3D visualizations (electroanatomic mapping system) to planning CT slices (2D) was subjective and very time consuming. Advanced methods are based on merging of electroanatomic maps (EAM) with CT. To date, 2 types of EAM-CT merge were proposed: manual alignment of EAM structures with segmented CT structures [1,2] and use of semi-automatic algorithm [3]. The goal of this work was to modify current method [2] with the use of robust automatic algorithms to assure reasonably short learning curve. This work is based on data of 10 patients who had previously undergone SBRT treatment for ventricular tachycardia (VT). Two observers participated in this study: (1) an electrophysiologist technician (cardiology) with substantial experience in EAM-CT merge, and (2) a clinical engineer (radiotherapy) with minimum experience with EAM-CT merge. Observer (1) performed EAM-CT merge three times for each case with an interval of at least 8h. Observer (2) did EAM-CT merge once for each patient following instructions written by observer 1. EAM-CT merge consist of 3 main steps: segmentation of left ventricle from CT (CT LV), registration of the CT LV and EAM, CTV delineation from EAM specific points. Mean Hausdorff distance (MHD), Dice Similarity Coefficient (DSC) and absolute difference in Center of Gravity (CoG) were used to assess intra/interobserver variability. All quantitative data was expressed as the mean and SD. Intraobserver variability Three segmented CT LVs were compared with each other. The mean DSC was 0,92±0,01 for all cases. The MHD was 1,49 ± 0,23 mm and the mean absolute difference in CoG coordinates was <1.5mm for all cases. The mean DSC and MHD for 3 CTVs altogether was 0,82±0,06 and 0,71 ±0,22 mm. The mean absolute difference in CoG was 0,64mm, 0,95mm and 0,78mm for X, Y, and Z coordinates, respectively. Interobserver variability Segmented CT LVs showed great similarity (mean DSC of 0,91±0,01, MHD of 1,86±0,47 mm) for all cases. The mean DSC comparing CTVs from both observers was 0,81±0,11 and MHD was 0,87±0,45 mm. The difference in CT LV volumes correlates with DSC of compared CTVs (Pearson´s correlation coefficient R = 0,8, p = 0,005) indicating that accurate segmentation of CT LV is crucial for successful precise CTV delineation. Modification of the current method based on incorporating automatic algorithms created a robust and fast method for CTV delineation. High similarity of both, the segmented CT LVs and delineated CTVs between observers confirmed robustness of the proposed method and steep learning curve.

Tractor Stability for Agricultural Engineering Students: Learning Through a Project-Based Task

Most of the fatalities in the agricultural sector in developed countries are related to machinery use, particularly tractor overturning. Despite its importance, a lack of practical teaching about this topic has been detected in the Agricultural Engineering curricula. For this reason, an active learning activity was planned within a teaching innovation project. The objective of this project was to design a structure as new teaching material to implement and use it to determine the tractor’s center of gravity coordinates. This teaching innovation project was organized in two stages: 1) The design of proposals by students following previously established requirements, and 2) A practical exercise to analyze tractor stability. Each stage involved students from two different Agricultural Engineering degree subjects. Before the second stage, the professor performed the final design of the structure based on previous proposals and later the structure was built. Five different ramp design proposals were received and graded in the first stage. A positive correlation between peer review and the professor’s grades was found. During the second stage, the ramps were used in another subject, in which the grades obtained in the related practical exercise were significantly higher in comparison with those got in the previous year. However, no improvement was found in the final exam grades. This activity involved students in the entire learning process and showed a positive influence on some of the evaluation activities.

Comprehensive Analysis of Minibuses Gravity Center: A Post-Production Review for Car Body Industry

The center of gravity (CoG) on the minibus is one of the fundamental parameters that affect the operation of the vehicle to maintain traffic safety. CoG greatly affects vehicle maneuverability due to load transfer between the front and rear wheels, such as when turning, braking, and accelerating. Therefore, this research was conducted to evaluate the operational safety of minibusses produced by the domestic car body industry. The case study was conducted on a minibus with a capacity of 30 passengers to be used in a mining area. Investigations on CoG were carried out based on the minibus specification data, especially the dimensions and forces acting on the wheels. Minibusses as test objects were categorized in two conditions, namely without passengers and with 30 passengers. The test results are expressed in a coordinate system (x, y, z) which represents the longitudinal, lateral, and vertical distances to the center of the front wheel axle. CoG coordinate values ​​without passengers are (2194.92; 7.11; 1327.97) mm and CoG coordinates with full passengers (30 people) are (2388.52; 13.04; 1251.72) mm. The test results show that the change in CoG at full load is not significant which indicates the minibus is safe when maneuvering under normal conditions.

Linear Potentials in Galaxy Halos by Asymmetric Wormholes

A spherically symmetric space-time solution for a diffusive two measures theory is studied. An asymmetric wormhole geometry is obtained where the metric coefficients has a linear term for galactic distances and the analysis of Mannheim and collaborators, can then be used to describe the galactic rotation curves. For cosmological distances a de-Sitter space-time is realized. Center of gravity coordinates for the wormhole are introduced which are the most suitable for the collective motion of a wormhole. The wormholes connect universes with different vacuum energy densities which may represent different universes in a “landscape scenario”. The metric coefficients depend on the asymmetric wormhole parameters. The coefficient of the linear potential is proportional to both the mass of the wormhole and the cosmological constant of the observed universe. Similar results are also expected in other theories like k-essence theories, that may support wormholes.

Spatial and Temporal Effects of Capsaicin and Menthol on Intraoral Somatosensory Sensitivity

To assess the spatial and temporal sensory effects of the topical application of capsaicin and menthol on the gingiva of healthy volunteers. Capsaicin, menthol, and saline (control) were applied topically on the gingiva in the maxillary premolar area of healthy volunteers for 15 minutes. Pain intensity was rated on a 0 to 10 visual analog scale (VAS). Before, immediately after, and 30 minutes after application, three mechanical stimuli were applied at 15 gingival sites: fixed-intensity stimuli were applied by 32 mN and 512 mN von Frey filaments, and stimuli of increasing intensity were applied by an electronic von Frey (EVF, 10 g/s). The EVF was used to test the pinprick pain threshold (PiPT). The perceived pain from filament stimulation was rated on a 0-50-100 numeric rating scale (NRS). Analysis of variance for repeated measures was used to analyze the NRS scores, PiPT values, the number of hypersensitive or hyposensitive test sites, and the coordinates of the center of gravity (COG) of somatosensory sensitivity. The mean ± SEM VAS score of pain intensity produced by the application of capsaicin (4.6 ± 0.5) was significantly higher than that produced by menthol (0.3 ± 0.2) and saline (0.1 ± 0.1) (P < .001). Capsaicin induced local desensitization to all stimuli (P < .047) , and at the application site, capsaicin induced significant desensitization to 512 mN stimuli (P = .003). Menthol did not induce significant somatosensory changes (P > .147), and saline induced slight desensitization in two sites surrounding the application site (P < .023). The COG coordinates did not shift significantly over time during any condition (P > .125). Capsaicin but not menthol induced mechanical desensitization in the application area but not in the surrounding areas.

Test rig for measuring the center of gravity coordinates and inertia tensor of spacecrafts: Data acquisition and control system

We consider data acquisition and control system used in the test rig for measuring the center of gravity coordinates and inertia tensor of spacecrafts. Structure of the system is described. Technical specifications and metrological parameters are presented for the module which measures static and dynamic signals of strain gauge dynamometers and for the module which measures the signals of angular oscillation sensor installed on the test rig measuring platform; these oscillations are generated using electric motors and special control hardware. Finally, we describe the system software used to acquire and process the data and to display the measurement results.

Characteristics of referred muscle pain to the head from active trigger points in women with myofascial temporomandibular pain and fibromyalgia syndrome

Our aim was to compare the differences in the prevalence and the anatomical localization of referred pain areas of active trigger points (TrPs) between women with myofascial temporomandibular disorder (TMD) or fibromyalgia (FMS). Twenty women (age 46 ± 8 years) with TMD and 20 (age 48 ± 6 years) with FMS were recruited from specialized clinic. Bilateral temporalis, masseter, sternocleidomastoid, upper trapezius, and suboccipital muscles were examined for TrPs. TrPs were identified by palpation and considered active when the pain reproduced familiar pain symptom experienced by the patient. The referred pain areas were drawn on anatomical maps, digitalized and also measured. A new analysis technique based on a center of gravity (COG) method was used to quantitative estimate of the localization of the TrP referred pain areas. Women with FMS exhibited larger areas of usual pain symptoms than women with myofascial TMD (P < 0.001). The COG coordinates of the usual pain on the frontal and posterior pain maps were located more superior in TMD than in FMS. The number of active TrPs was significantly higher in TMD (mean ± SD 6 ± 1) than in FMS (4 ± 1) (P = 0.002). Women with TMD exhibited more active TrPs in the temporalis and masseter muscles than FMS (P < 0.01). Women with FMS had larger referred pain areas than those with TMD for sternocleidomastoid and suboccipital muscles (P < 0.001). Significant differences within COG coordinates of TrP referred pain areas were found in TMD, the referred pain was more pronounced in the orofacial region, whereas the referred pain in FMS was more pronounced in the cervical spine. This study showed that the referred pain elicited from active TrPs shared similar patterns as usual pain symptoms in women with TMD or FMS, but that distinct differences in TrP prevalence and location of the referred pain areas could be observed. Differences in location of referred pain areas may help clinicians to determine the most relevant TrPs for each pain syndrome in spite of overlaps in pain areas.

Prevalence and Anatomical Localization of Muscle Referred Pain from Active Trigger Points in Head and Neck Musculature in Adults and Children with Chronic Tension-Type Headache

To compare differences in the prevalence and the anatomical localization of the referred pain areas of active trigger points (TrPs) in head and neck musculature between adults and children with chronic tension-type headache (CTTH). A cross-sectional study. Some studies had found that referred pain from active TrPs reproduce the head pain pattern in adults. No study has compared clinical differences between referred pain patterns elicited by active TrPs between adults and children with CTTH. Twenty adults (10 men, 10 women, mean age: 41 ± 11 years) and 20 children (10 boys, 10 girls, mean age: 8 ± 2 years) with CTTH were included. Bilateral temporalis, sternocleidomastoid, upper trapezius, and suboccipital muscles were examined for TrPs. TrPs were identified by palpation and considered active when local and referred pains reproduce the headache pain attacks. The referred pain areas were drawn on anatomical maps, digitalized, and also measured. An analysis technique based on a center of gravity (COG) method was used to provide a quantitative estimate of the localization of the TrP referred pain areas. Adults with CTTH exhibited a greater years with headache, higher intensity, and longer headache duration (P < 0.05) compared with children. The COG coordinates of the spontaneous pain on the dominant side were located more anterior (higher X-value), and spontaneous pain in the frontal and posterior areas was located more inferior (lower Y-value) in adults than in children. The number of active muscle TrPs was significantly higher (P = 0.001) in adults with CTTH (mean ± standard deviation [SD]: 4 ± 0.8) as compared with children (mean ± SD: 3 ± 0.7). Children with CTTH had larger referred pain areas than adults for upper trapezius, sternocleidomastoid, and temporalis (P < 0.001) muscles. The COG coordinates of the referred pain areas of temporalis and sternocleidomastoid muscle TrPs were more inferior (lower Y-values) in adults than in children with CTTH. This study showed that the referred pain elicited from active TrPs shared similar pain patterns as spontaneous CTTH in adults and children. Differences in TrP prevalence and location of the referred pain areas can be observed between adults and children with CTTH.

Research on Improving Friction Compensation of Large Structure's Weighing System

Large structures weighing systemis upgrading the structure simultaneously using several jacks. After structure leaves the ground, the hydraulic control check valve is used for hydraulic lock, and pressure sensor that under each jack measures the jack cavity pressure. Data is collected by PLC system to obtain the force situation of each jack. With the moment of inertia calculation, center of gravity coordinates of the plane is obtained, the weighing system involves in the hydraulic system, control system, data acquisition and transmission. As the jack wall friction and the leakage factors, in the measuring process, pressure sensor reflects little, and measurement errors appear. In this research, experimental research data has been used to obtain empirical formula under varying pressures, error has also been corrected in weighing measurement system in order to get high precision weighing data. The results are in good agreement after comparing this theory with results measured by weight sensor.

Digital signal processing and test rig testing results

Digital processing method of the vibrating system rotation angle in the measuring test rig is considered; it allows evaluating the eigenfrequency, amplitude and phase of the signal. The measurement results of the mass, center of gravity coordinates and inertia moments of the reference objects are provided. The measurement errors are determined.

Test rig for measuring the object's mass, center of gravity coordinates and inertia tensor

Certain equations for measuring the object's mass, coordinates of the center of inertia and the inertia tensor are derived. Description of the test rig implementing the measurement equations is presented.

Functional Characterization of Three G Protein-coupled Receptors for Pigment Dispersing Factors in Caenorhabditis elegans

Here, we report the identification, cloning, and functional characterization of three Caenorhabditis elegans G protein-coupled pigment dispersing factor (PDF) receptors, which we designated as Ce_PDFR-1a, -b, and -c. They represent three splice isoforms of the same gene (C13B9.4), which share a high degree of similarity with the Drosophila PDF receptor and are distantly related to the mammalian vasoactive intestinal peptide receptors (VPAC2) and calcitonin receptors. In a reverse pharmacological screen, three bioactive C. elegans neuropeptides, which were recently identified as the Drosophila PDF orthologues, were able to activate these receptors in a dose-dependent manner with nanomolar potency (isoforms a and b). Integrated green fluorescent protein reporter constructs reveal the expression of these PDF receptors in all body wall muscle cells and many head and tail neurons involved in the integration of environmental stimuli and the control of locomotion. Using a custom data analysis system, we demonstrate the involvement of this newly discovered neuropeptide signaling system in the regulation of locomotor behavior. Overexpression of PDF-2 phenocopies the locomotor defects of a PDF-1 null mutant, suggesting that they elicit opposite effects on locomotion through the identified PDF receptors. Our findings strengthen the hypothesis that the PDF signaling system, which imposes the circadian clock rhythm on behavior in Drosophila, has been functionally conserved throughout the protostomian evolutionary lineage.

TMS motor cortical brain mapping in patients with complex regional pain syndrome type I

Objective The motor cortical representation in patients with complex regional pain syndrome type I (CRPS I) was determined under the assumption that the motor cortex undergoes representational adaptations in the course of CRPS. Methods A total of 14 patients with CRPS I and a group of healthy subjects without any known neurological symptoms participated in the study. The motor cortical representation, i.e. the size of representation (cm 2), motor-evoked potentials (MEP), the calculated volume (cm 2 mV), and the center of gravity (CoG) were measured by transcranial magnetic stimulation. Recordings were made of the long extensor muscles of the forearm of the affected and unaffected hand. Results Analyses of the results revealed a significant asymmetry between the two hemispheres: the motor cortical representation corresponding to the unaffected hand was significantly larger. While the CoG data did not differ statistically between the two hemispheres, the CoG coordinates corresponding to the affected hand indicated a larger variability. Conclusions The presence of pain and other CRPS symptoms may induce lasting changes in motor cortical plasticity, as it also does in the sensory cortex. Significance This could be of importance in rehabilitative strategies for the sensory motor system in CRPS I patients.