Control of the Electron Energy Distribution Function (EEDF) in a Hall Thruster Plasma.

Further improvements to Hall-effect thruster (HET) efficiency in the low voltage regime will help enable more extensive space missions. HET efficiency depends on its ability to ionize and accelerate neutral propellant, which can be further improved when electrons with energies and trajectories that contribute to ionization are increased in the right locations. Therefore, electron energy distribution function (EEDF) tailoring is needed. However, predictive EEDF control in plasma devices is a challenging problem due to complex electromagnetic interactions that take place that lead to the turbulent nature of these plasmas. In an effort to control the HET’s EEDF to boost thruster efficiency, and to also uncover further insights into the operation and dynamics of these devices, various analyses were carried out. The last was a reverse-orientation cathode technique to control the EEDF by placing the cathode downstream and pointing towards the thruster to redirect high-energy electrons to a less circuitous path to ionization zones in the thruster’s channel. Total efficiency and its components were calculated from non-invasive thrust stand measurements and a suite of downstream thruster diagnostics respectively. For the test thruster’s nominal operating condition, total efficiency increased by 3 percentage points with the external, downstream cathode when compared to the standard, central cathode configuration; however, for an off-nominal condition, thruster efficiency decreased by 1 percentage point. For both operating conditions, the EEDFs revealed that external cathode electron temperatures were on average about half that of the corresponding central cathode values at the downstream data-taking locations. The results implied that the reverse-orientation cathode placed more control on directing high-energy electrons into the thruster channel since less were in downstream locations. These EEDF changes most likely correlated with an increase in efficiency for only the nominal condition due to larger ion beam divergence in the off-nominal condition. However, to confirm these inferences, internal ion current density and divergence measurements where thrust is produced are needed. Therefore, this EEDF control quest made clear the need for non-invasive, performance diagnostic measurements inside the channel to draw more direct conclusions not only about this method’s results, but also about thruster performance and dynamics in general.PHDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/135858/1/kimtrent_1.pd

Physiological Responses to Active Video Games Compared to Treadmill Walking and TV Watching in Obese Children and Adolescents

International Journal of Exercise Science 14(7): 519-532, 2021. The purpose of this study was to examine the physiological responses to playing different active video games (AVG), as well as document the activity level exerted during AVG in relation to treadmill walking (TM) and watching television (TV). 20 youth (age 11-17 yr) with obesity were recruited from the Healthy Lifestyle Clinic and underwent testing under six randomized conditions: 1) TM, 2) TV, 3) Fitnexx, 4) river rush (RRH), 5) reflex ridge (RFR), and 6) space pop (SP). RRH, RFR, and SP are active video games for the Xbox 360. Fitnexx is a prototype AVG. Each test lasted approximately ten minutes each with ten minutes between conditions and participants wore a wireless physiological monitor (Zephyr BioHarnessTM3) for all tests. Physical activity was assessed via accelerometer, along with heart rate (HR). Rating of Perceived Exertion (RPE) was also gathered for each condition. Repeated-measures ANOVA examined condition differences. Subjects were age 13.3 ± 2.1 years old with BMI 38.7 ± 7.9 (kg·m·s-2). Fitnexx had the highest activity level (0.63 ± 0.19g ~ jog), while activity levels for TM (0.20 ± 0.04g), RRH (0.29 ± 0.05g), RFR (0.31 ± 0.07g), and SP (0.21 ± 0.05g) were moderate (~walk), Ps \u3c 0.05. Fitnexx had the highest HR (157 ± 13 bpm; Ps \u3c 0.001), compared to TM (117 ± 18 bpm), RRH (128 ± 19 bpm), RFR (127 ± 18 bpm), and SP (122 ± 17 bpm), which were statistically similar. Rating of Perceived Exertion (RPE) was highest for Fitnexx (5 ± 4 RPE) compared to TM (2 ± 1 RPE) on 0 - 10 scale. TV had lowest activity, HR, and RPE (p \u3c 0.04). Given these results, AVG can increase activity levels in youth with obesity and has potential as a therapeutic tool for obese children

Effects of patient health literacy, patient engagement and a system-level health literacy attribute on patient-reported outcomes: A representative statewide survey

BACKGROUND: The effects of health literacy are thought to be based on interactions between patients’ skill levels and health care system demands. Little health literacy research has focused on attributes of health care organizations. We examined whether the attribute of individuals’ experiences with front desk staff, patient engagement through bringing questions to a doctor visit, and health literacy skills were related to two patient-reported outcomes. METHODS: We administered a telephone survey with two sampling frames (i.e., household landline, cell phone numbers) to a randomly selected statewide sample of 3358 English-speaking adult residents of Missouri. We examined two patient-reported outcomes – whether or not respondents reported knowing more about their health and made better choices about their health following their last doctor visit. Multivariable logistic regression models were used to examine the independent contributions of predictor variables (i.e., front desk staff, bringing questions to a doctor visit, health literacy skills). RESULTS: Controlling for self-reported health, having a personal doctor, time since last visit, number of chronic conditions, health insurance, and sociodemographic characteristics, respondents who had a good front desk experience were 2.65 times as likely (95% confidence interval [CI]: 2.13, 3.30) and those who brought questions were 1.73 times as likely (95% CI: 1.32, 2.27) to report knowing more about their health after seeing a doctor. In a second model, respondents who had a good front desk experience were 1.57 times as likely (95% CI: 1.26, 1.95) and those who brought questions were 1.66 times as likely (95% CI: 1.29, 2.14) to report making better choices about their health after seeing a doctor. Patients’ health literacy skills were not associated with either outcome. CONCLUSIONS: Results from this representative statewide survey may indicate that one attribute of a health care organization (i.e., having a respectful workforce) and patient engagement through question asking may be more important to patient knowledge and health behaviors than patients’ health literacy skills. Findings support focused research to examine the effects of organizational attributes on patient health outcomes and system-level interventions that might enhance patient health

Genome sequence of the organohalide-respiring Dehalogenimonas alkenigignens type strain (IP3-3(T))

Dehalogenimonas alkenigignens IP3-3(T) is a strictly anaerobic, mesophilic, Gram negative staining bacterium that grows by organohalide respiration, coupling the oxidation of H-2 to the reductive dehalogenation of polychlorinated alkanes. Growth has not been observed with any non-polyhalogenated alkane electron acceptors. Here we describe the features of strain IP3-3(T) together with genome sequence information and its annotation. The 1,849,792 bp high-quality-draft genome contains 1936 predicted protein coding genes, 47 tRNA genes, a single large subunit rRNA (23S-5S) locus, and a single, orphan, small unit rRNA (16S) locus. The genome contains 29 predicted reductive dehalogenase genes, a large majority of which lack cognate genes encoding membrane anchoring proteins.

The Hawaii Infrared Parallax Program. VI. The Fundamental Properties of 1000+ Ultracool Dwarfs and Planetary-mass Objects Using Optical to Mid-IR SEDs and Comparison to BT-Settl and ATMO 2020 Model Atmospheres

We derive the bolometric luminosities ($L_{\mathrm{bol}}$) of 865 field-age and 189 young ultracool dwarfs (spectral types M6-T9, including 40 new discoveries presented here) by directly integrating flux-calibrated optical to mid-IR spectral energy distributions (SEDs). The SEDs consist of low-resolution ($R\sim$ 150) near-IR (0.8-2.5 $\mu$m) spectra (including new spectra for 97 objects), optical photometry from the Pan-STARRS1 survey, and mid-IR photometry from the CatWISE2020 survey and Spitzer/IRAC. Our $L_{\mathrm{bol}}$ calculations benefit from recent advances in parallaxes from Gaia, Spitzer, and UKIRT, as well as new parallaxes for 19 objects from CFHT and Pan-STARRS1 presented here. Coupling our $L_{\mathrm{bol}}$ measurements with a new uniform age analysis for all objects, we estimate substellar masses, radii, surface gravities, and effective temperatures ($T_{\mathrm{eff}}$) using evolutionary models. We construct empirical relationships for $L_{\mathrm{bol}}$ and $T_{\mathrm{eff}}$ as functions of spectral type and absolute magnitude, determine bolometric corrections in optical and infrared bandpasses, and study the correlation between evolutionary model-derived surface gravities and near-IR gravity classes. Our sample enables a detailed characterization of BT-Settl and ATMO 2020 atmospheric model systematics as a function of spectral type and position in the near-IR color-magnitude diagram. We find the greatest discrepancies between atmospheric and evolutionary model-derived $T_{\mathrm{eff}}$ (up to 800 K) and radii (up to 2.0 $R_{\mathrm{Jup}}$) at the M/L transition boundary. With 1054 objects, this work constitutes the largest sample to date of ultracool dwarfs with determinations of their fundamental parameters.Comment: Resubmitted to The Astrophysical Journal (ApJ) after a positive referee report. 51 pages, 29 figures, 7 tables. Data presented in this work: https://doi.org/10.5281/zenodo.8315643. Scripts associated with methods: https://github.com/cosmicoder/HIPPVI-Cod

Camilla: A Centaur reconnaissance and impact mission concept

Centaurs, minor planets with a semi-major axis between the orbits of Jupiter and Neptune (5–30 AU), are thought to be among the most diverse small bodies in the solar system. These important targets for future missions may have recently been Kuiper Belt Objects (KBOs), which are thought to be chemically and physically primitive remnants of the early solar system. While the Kuiper Belt spans distances of 30–50 AU, making direct observations difficult, Centaurs' proximity to the Earth and Sun make them more accessible targets for robotic missions. Thus, we outline a mission concept designed to reconnoiter 10199 Chariklo, the largest Centaur and smallest ringed body yet discovered. Named for a legendary Centaur tamer, the conceptual Camilla mission is designed to fit under the cost cap of the National Aeronautics and Space Administration (NASA) New Frontiers program, leveraging a conservative payload to support a foundational scientific investigation to these primitive bodies. Specifically, the single flyby encounter utilizes a combined high-resolution camera/VIS-IR mapping spectrometer, a sub-mm point spectrometer, and a UV mapping spectrometer. In addition, the mission concept utilizes a kinetic impactor, which would provide the first opportunity to sample the composition of potentially primitive subsurface material beyond Saturn, thus providing key insights into solar system origins. Such a flyby of the Chariklo system would provide a linchpin in the understanding of small body composition, evolution, and transport of materials in the solar system