Proto-Brown Dwarf Disks as Products of Protostellar Disk Encounters

The formation of brown dwarfs via encounters between proto-stars has been confirmed with high-resolution numerical simulations with a restricted treatment of the thermal conditions. The new results indicate that young brown dwarfs (BDs) formed this way are disk-like and often reside in multiple systems. The newly-formed proto-BDs disks are up to 18 AU in size and spin rapidly making small-scale bipolar outflows, fragmentation and the possible formation of planetary companions likely as have recently been observed for BDs. The object masses range from 2 to 73 Jupiter masses, distributed in a manner consistent with the observed sub-stellar initial mass function. The simulations usually form multiple BDs on eccentric orbits about a star. One such system was hierarchical, a BD binary in orbit around a star, which may explain recently observed hierarchical systems. One third of the BDs were unbound after a few thousand years and interactions among orbiting BDs may eject more or add to the number of binaries. Improvements over prior work include resolution down to a Jupiter mass, self-consistent models of the vertical structure of the initial disks and careful attention to avoid artificial fragmentation.Comment: 4 pages, 3 figures, accepted for publication in ApJ Letter

Equity, gender and health: New directions for global men’s health promotion

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154916/1/hpja337_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154916/2/hpja337.pd

An Inquiry into the Aviation Management Education Paradigm Shift

Working adults with four-year degrees from accredited colleges or universities earn, on average, almost three times more than individuals without a degree. This pay gap led Newcomer and his colleagues to study attitudes of aviation and aerospace managers towards education. That study found that managers valued education in new hires, even though they did not deem it critical to their own positions. That finding indicated a potential paradigm shift towards the perceived value of education in the industry. In the current qualitative, phenomenological research, we interviewed 14 managers from various capacities within the aviation and aerospace industries to determine the relative importance of education, certification, and experience when hiring or selecting new team members. The results indicated that managers value experience most when making staffing decisions. Next, they value certification or education, depending on the technical or managerial role. A majority of the managers did express that their attitudes towards the value of education had become stronger over their careers. The study has hiring implications for aviation and aerospace managers, as well as employees, in terms of what to focus on in interviews and in reviewing candidate credentials

Hydrogen isotope behavior during rhyolite glass hydration under hydrothermal conditions

The diffusion of molecular water (H2Om) from the environment into volcanic glass can hydrate the glass up to several wt% at low temperature over long timescales. During this process, the water imprints its hydrogen isotope composition (δDH2O) to the glass (δDgl) offset by a glass-H2O fractionation factor (ΔDgl-H2O = δDgl – δDH2O) which is approximately -33‰ at Earth surface temperatures. Glasses hydrate much more rapidly at higher, sub-magmatic temperatures as they interact with H2O during eruption, transport, and emplacement. To aid in the interpretation of δDgl in natural samples, we present hydrogen isotope results from vapor hydration experiments conducted at 175–375 oC for durations of hours to months using natural volcanic glasses. The results can be divided into two thermal regimes: above 250 oC and below 250 oC. Lower temperature experiments yield raw ΔDgl-H2O values in the range of -33 ± 11‰. Experiments at 225 oC using both positive and negative initial ΔDgl-H2O values converge on this range of values, suggesting this range represents the approximate equilibrium fractionation for H isotopes between glass and H2O vapor (103lnαgl-H2O) below 250 oC. Variation in ΔDgl-H2O (-33 ± 11‰) between different experiments and glasses may arise from incomplete hydration, analytical uncertainty, differences in glass chemistry, and/or subordinate kinetic isotope effects. Experiments above 250 oC yield unexpectedly low δDgl values with ΔDgl-H2O values of ≤–85‰. While alteration alone is incapable of explaining the data, these run products have more extensive surface alteration and are not interpreted to reflect equilibrium fractionation between glass and H2O vapor. Fourier transform infrared spectroscopy (FTIR) shows that glass can hydrate with as much as 5.9 wt% H2Om and 1.0 wt% hydroxl (OH-) in the highest P-T experiment at 375 oC and 21.1 MPa. Therefore, we employ a 1D isotope diffusion– reaction model of glass hydration to evaluate the roles of equilibrium fractionation, isotope diffusion, water speciation reactions internal to the glass, and changing boundary conditions (e.g. alteration and dissolution). At lower temperatures, the best fitting model results to experimental data for low silica rhyolite (LSR) glasses require only an equilibrium fractionation factor and yield 103lnαgl-H2O values of -33‰± 5‰and -25‰± 5‰at 175 oC and 225 oC, respectively. At higher temperatures, ΔDgl-H2O is dominated by boundary layer effects during glass hydration and glass surface alteration. The modeled bulk δDgl value is highly responsive to changes in the δDgl boundary condition regardless of the magnitude of other kinetic effects. Observed glass dissolution and surficial secondary mineral formation are likely to impose a disequilibrium boundary layer that drives extreme δDgl fractionation with progressive glass hydration. These results indicate that the observed ΔDgl-H2O of ~-33 ± 11‰ can be cautiously applied as an equilibrium 103lnαgl-H2O value to natural silicic glasses hydrated below 250 oC to identify hydration sources. This approximate ΔDgl-H2O may be applicable to even higher temperature glasses hydrated on short timescales (of seconds to minutes) in phreatomagmatic or submarine eruptions before H2O in the glass is primarily affected by boundary layer effects associated with alteration on the glass surface

A cross-sectional investigation of the relationships education, certification, and experience have with knowledge, skills, and abilities among aviation professionals

The aviation industry is a complex system with many different segments and as such, makes hiring the right person a complicated endeavor. Previous research suggested that knowledge, skills, and abilities (KSAs) are composed of elements that include education, certification, and experience (ECE). The relative importance of ECE is dependent on the type of job within the aviation sector. The objective of this mixed-methods concurrent triangulation study was to examine aviation industry professionals’ perceived relationship between their ECE and the development of their KSAs. The convenience sample consisted of 404 professionals in the aviation industry who completed the KSA Composite Measure (KCM). The study clarified relationships between ECEs and KSAs that managers in the aviation industry can apply when developing job openings, conducting interviews, reviewing applicant credentials, and building high-performance teams

EC03-1884 Wheat Disease Profiles I

This two-page, 4-color extension circular covers the disease and symptoms of wheat in Nebraska. The diseases listed are: barley yellow dwarf, soil-borne wheat mosaic, wheat streak mosaic, leaf rust, stem rust, stripe rust, tan spot, septoria leaf blotch, common root rot, crown rot, Fusarium head blight (scab)

EC03-1884 Wheat Disease Profiles I

This two-page, 4-color extension circular covers the disease and symptoms of wheat in Nebraska. The diseases listed are: barley yellow dwarf, soil-borne wheat mosaic, wheat streak mosaic, leaf rust, stem rust, stripe rust, tan spot, septoria leaf blotch, common root rot, crown rot, Fusarium head blight (scab)

EC02-1883 Corn Disease Profiles

This two-page, four-color extension circular covers the many diseases of corn in Nebraska. It list and describes corn diseases such as: anthracnose, common smut, bacterial stalk rot and top rot, holcus spot, Stewart\u27s Wilt, Goss\u27s bacterial wilt and blight, common rust, southern rust, and gray leaf rust

Validating the Knowledge, Skills, and Abilities Composite Measure: An Aviation Industry Pilot Study

Recent research into the aviation management education paradigm shift indicated that education, certification, and experience (ECE) were all important in the aviation industry; however, the relative importance varied between managers depending on their field. Overall, the results identified experience as the most important factor, followed by certification, then education. Furthermore, the authors made a logical connection between the that study and knowledge, skills, and abilities (KSAs), which would ultimately lead managers to a hiring decision. The purpose of this mixed-methods sequential exploratory pilot study was to develop, validate, and test the reliability of the KSA composite measure (KCM), a data collection device to measure the connection between ECE and KSAs. The three phased approach consisted of (a) an expert panel review by eight research, aviation, and human resource professionals, (b) an institutional review board (IRB) review, and (c) a live pilot using 45 professionals from the aviation industry. The pilot proved to validate and confirm the reliability of the KCM for future use