Effect of Wearing a Maxillofacial Prosthesis on Masticatory Rhythm Improvement in Mandibulectomy Patients

Background: Recording jaw movement rhythms in patients with jaw defects is challenging using conventional tracking devices. However, masticatory rhythm is crucial for masticatory performance and nutritional intake. This study aimed to explore the impact of using a maxillofacial prosthesis to restore masticatory rhythm in mandibulectomy patients with a novel wearable device. Methods: Twelve patients who underwent mandibulectomy and were rehabilitated with maxillofacial prosthesis were recruited. Chewing rate, cycle durations, coefficient of variation of cycle durations (CV), changing times of skin morphology on the back of the ear pinna area (SM), and masticatory performance were measured during gum chewing without and with a denture using a wearable jaw movement rhythm tracking device. A paired t-test and the Pearson correlation coefficient were used for statistical analysis. Results: The chewing rate increased by 8.6 cycles/min with dentures (P P = 0.01). The CV and SM decreased with dentures (P = 0.004 and P = 0.01, respectively). Significant correlations were found between the CV and SM without dentures (P = 0.004). Conclusion: 1. Wearing maxillofacial prostheses can improve masticatory rhythm in patients who undergo mandibulectomy with Eichner B2 occlusal supports. 2. The wearable device is available for measuring masticatory rhythm in patients with jaw defects in clinics. 3. Changing times of the skin morphology on the back of the ear pinna indicate jaw movement stability through a simpler process than the coefficient of variation of cycle durations.

Generation mechanism and control of high-frequency vibration for tracked vehicles

A crawler system provides much larger ground contact,leading to excellent terrain adaptability.Due to its structural characteristics,high‐frequency vibration proportional to the vehicle speed is generated during the driving process.This is a result of the polygon and rolling effects between the track and the wheels.A field test of a tracked vehicle is performed to monitor movement signals of the chassis and a rocker arm.Their corresponding power spectral density distributions confirm the correctness of the frequency‐calculation equation.Then,a novel elastic track tensioning device with a damper is designed as a cushion between the idler and the chassis.Depending on its geometry,the equivalent damping coefficient for a dynamic model is evaluated.Subsequently,the damping is altered in response to different operating conditions by a hybrid damping fuzzy semiactive control system.The controller accounts for both chassis and track vibration.Based on the transfer matrix method for multibody systems,a dynamical model of the track system is developed.Control performances are evaluated using two numerical simulations of obstacle crossing and off‐road driving operations.Results indicate that the proposed semiactive tensioner is substantially better than the conventional one.This paper provides a novel feasible scheme for vibration reduction of tracked vehicles.

Using accelerometry to compare costs of extended migration in an arctic herbivore

Understanding how individuals manage costs during the migration period is challenging because individuals are difficult to follow between sites; the advent of hybrid Global Positioning Systemacceleration （ACC） tracking devices enables researchers to link spatial and temporal attributes of avian migration with behavior for the first time ever. We fitted these devices on male Greenland white-fronted geese Anser albifrons flavirostris wintering at 2 sites （Loch Ken, Scotland and Wexford, Ireland） to understand whether birds migrating further during spring fed more on winter- ing and staging areas in advance of migration episodes. Although Irish birds flew significantly further （ca. 300 kin） than Scottish birds during spring, their cumulative hours of migratory flight, flight speed during migration, and overall dynamic body ACC （i.e., a proxy for energy expenditure） were not significantly different. Further, Irish birds did not feed significantly more or expend significantly more energy in advance of migration episodes. These results suggest broad individual plasticity in this species, although Scottish birds arriving on breeding areas in Greenland with greater energy stores （because they migrated less） may be better prepared for food scarcity, which might increase their reproductive success.