Evaluation of the Effects on Human Performance Characteristics and Peak Head Accelerations With the Use of Various Intra-Oral Appliances

Various studies have investigated the relationship between the mandibular position and its affect on human performance characteristics. To maintain the jaw in an optimal position Mandibular Orthopedic Repositioning Appliances (MORA) have been produced. A protective mouthguard is an appliance worn in the mouth which helps prevent injuries to the teeth, lips, cheek, tongue, and jaw as a result of impact. More recently, it has been hypothesized that mouthguards reduce the risk of concussion by attenuating the impact to the jaw rather than transferring the force to the brain. Currently, there are no standards for testing protective mouthguards. Such a test would prove useful to determine maximum acceleration levels of the head. The aim of this study is to (1) quantify the effectiveness of repositioning the jaw on strength and aerobic potential as well as (2) to determine if a protective mouthguard can give the same affects of a MORA device. In addition (3) a test protocol will be established for the evaluation of mouthguard performance. The data collected will show how well the EDGETM Protection performs versus other consumer available mouthguards on the criteria of attenuation of peak head accelerations. After statistical analysis, it was found on a 95% confidence level that the MORA and the protective mouthguard with MORA attributes increase a user’s strength. On certain intervals of the aerobic testing there was evidence that the MORA does have an influence on human performance

A 2-Question Summative Score Correlates with the Maslach Burnout Inventory

Introduction: There is a high prevalence of burnout among emergency medicine (EM) residents. The Maslach Burnout Inventory - Human Services Survey (MBI-HSS) is a widely used tool to measure burnout. The objective of this study was to compare the MBI-HSS and a two-question tool to determine burnout in the EM resident population.Methods: Based on data from the 2017 National Emergency Medicine Resident Wellness Survey study, we determined the correlation between two single-item questions with their respective MBI subscales and the full MBI-HSS. We then compared a 2-Question Summative Score to the full MBI-HSS with respect to primary, more restrictive, and more inclusive definitions of burnout previously reported in the literature.Results: Of 1,522 residents who completed the survey 37.0% reported “I feel burned out from my work,” and 47.1% reported “I have become more callous toward people since I took this job” once a week or more (each item >3 on a scale of 0-6). A 2-Question Summative Score totaling >3 correlated most closely with the primary definition of burnout (Spearman’s rho 0.65 [95% confidence interval 0.62-0.68]). Using the summative score, 77.7% of residents were identified as burned out, compared to 76.1% using the full MBI-HSS, with a sensitivity and specificity of 93.6% and 73.0%, respectively.Conclusion: An abbreviated 2-Question Summative Score correlates well with the full MBI-HSS tool in assessing EM resident physician burnout and could be considered a rapid screening tool to identify at-risk residents experiencing burnout

Resolving the H-alpha-emitting Region in the Wind of Eta Carinae

The massive evolved star Eta Carinae is the most luminous star in the Milky Way and has the highest steady wind mass-loss rate of any known star. Radiative transfer models of the spectrum by Hillier et al. predict that H-alpha is mostly emitted in regions of the wind at radii of 6 to 60 AU from the star (2.5 to 25 mas at 2.35 kpc). We present diffraction-limited images (FWHM ~25 mas) with Magellan adaptive optics in two epochs, showing that Eta Carinae consistently appears ~2.5 to 3 mas wider in H-alpha emission compared to the adjacent 643 nm continuum. This implies that the H-alpha line-forming region may have a characteristic emitting radius of 12 mas or ~30 AU, in very good agreement with the Hillier stellar-wind model. This provides direct confirmation that the physical wind parameters of that model are roughly correct, including the mass-loss rate of 10^-3 M_sun/yr, plus the clumping factor, and the terminal velocity. Comparison of the H-alpha images (ellipticity and PA) to the continuum images reveals no significant asymmetries at H-alpha. Hence, any asymmetry induced by a companion or by the primary's rotation do not strongly influence the global H-alpha emission in the outer wind.Comment: Published in ApJ

New Extinction and Mass Estimates from Optical Photometry of the Very Low Mass Brown Dwarf Companion CT Chamaeleontis B with the Magellan AO System

We used the Magellan adaptive optics (MagAO) system and its VisAO CCD camera to image the young low mass brown dwarf companion CT Chamaeleontis B for the first time at visible wavelengths. We detect it at r', i', z', and Ys. With our new photometry and Teff~2500 K derived from the shape its K-band spectrum, we find that CT Cha B has Av = 3.4+/-1.1 mag, and a mass of 14-24 Mj according to the DUSTY evolutionary tracks and its 1-5 Myr age. The overluminosity of our r' detection indicates that the companion has significant Halpha emission and a mass accretion rate ~6*10^-10 Msun/yr, similar to some substellar companions. Proper motion analysis shows that another point source within 2" of CT Cha A is not physical. This paper demonstrates how visible wavelength AO photometry (r', i', z', Ys) allows for a better estimate of extinction, luminosity, and mass accretion rate of young substellar companions.Comment: Accepted for publication in ApJ; 6 figure

New Extinction and Mass Estimates of the Low-mass Companion 1RXS 1609 B with the Magellan AO System: Evidence of an Inclined Dust Disk

We used the Magellan adaptive optics system to image the 11 Myr substellar companion 1RXS 1609 B at the bluest wavelengths to date (z' and Ys). Comparison with synthetic spectra yields a higher temperature than previous studies of $T_\mathrm{eff}=2000\pm100\mathrm{K}$ and significant dust extinction of $A_V=4.5^{+0.5}_{-0.7}$ mag. Mass estimates based on the DUSTY tracks gives 0.012-0.015 Msun, making the companion likely a low-mass brown dwarf surrounded by a dusty disk. Our study suggests that 1RXS 1609 B is one of the 25% of Upper Scorpius low-mass members harboring disks, and it may have formed like a star and not a planet out at 320 AU.Comment: 5 pages, 4 figures; accepted to ApJ

The Intricate Structure of HH 508, the Brightest Microjet in the Orion Nebula

We present Magellan adaptive optics H$\alpha$ imaging of HH 508, which has the highest surface brightness among protostellar jets in the Orion Nebula. We find that HH 508 actually has a shorter component to the west, and a longer and knotty component to the east. The east component has a kink at 0.3" from the jet-driving star $\theta^1$ Ori B2, so it may have been deflected by the wind/radiation from the nearby $\theta^1$ Ori B1B5. The origin of both components is unclear, but if each of them is a separate jet, then $\theta^1$ Ori B2 may be a tight binary. Alternatively, HH 508 may be a slow-moving outflow, and each component represents an illuminated cavity wall. The ionization front surrounding $\theta^1$ Ori B2B3 does not directly face $\theta^1$ Ori B1B5, suggesting that the EUV radiation from $\theta^1$ Ori C plays a dominant role in affecting the morphology of proplyds even in the vicinity of $\theta^1$ Ori B1B5. Finally, we report an H$\alpha$ blob that might be ejected by the binary proplyd LV 1.Comment: 4 pages. Published in Ap