Spotlight on Scholarly Commons, June 2017 - Worldwide

Faculty with notable downloads: Aman Gupta Kelly Whealan-George James Marion, Jr. Tracey Richardson Matthew Earnhardt Brent Terwilliger Dennis Vincenzi David Ison Kenneth Witcher David Thirtyacre Adeel Khalid Worldwide Faculty Submission Statistics: Total Papers: 49 All-time Downloads: 12,715 June Downloads: 368 *Statistics are for the Worldwide Campus publication

Spotlight on Scholarly Commons, June 2017 - Prescott

Faculty with notable downloads: Timothy Holt Mohammad Moallemi Linda Wieland Matt Earnhardt Sonya McMullen Prescott Faculty Submission Statistics: Total Papers: 148 All-time Downloads: 84,574 June Downloads: 1,189 Other Interesting Information: Issues of the Pioneer, ERAU Prescott\u27s official newspaper 1978-1983 have been digitized and published. Several SelectedWorks sites have been created. *Statistics are for the Prescott Campus publication

Spotlight on Scholarly Commons, June 2017 - Daytona Beach

Faculty with notable downloads: Anke Arnaud Gary Kessler Guy Smith William Barott William Lahneman Daytona Beach Faculty Submission Statistics: Total Papers: 553 All-time Downloads: 61,693 June Downloads: 1,738 Other Interesting Information: The LHUFT Center and ICAEA were brought online. *Statistics are for the Daytona Beach Campus publication

Scholarly Commons Annual Report 2017-2018

Scholarly Commons continues to showcase ERAU research globally. While the number of submissions increased by 11.85% over FY 17, downloads grew by 43.89% in FY 18. In addition, new conferences, such as the 2018 International Civil Aviation English Association (ICAEA) and ERAU’s AviAsian Conference, were added. The annual ICAEA Conference is held in a different international location each year and the Daytona Beach Campus served as the host this year. The AviAsian Conference is sponsored on ERAU’s Singapore Campus by faculty from that area

Fully coupled photochemistry of the deuterated ionosphere of Mars and its effects on escape of H and D

Although deuterium (D) on Mars has received substantial attention, the deuterated ionosphere remains relatively unstudied. This means that we also know very little about non-thermal D escape from Mars, since it is primarily driven by excess energy imparted to atoms produced in ion-neutral reactions. Most D escape from Mars is expected to be non-thermal, highlighting a gap in our understanding of water loss from Mars. In this work, we set out to fill this knowledge gap. To accomplish our goals, we use an upgraded 1D photochemical model that fully couples ions and neutrals and does not assume photochemical equilibrium. To our knowledge, such a model has not been applied to Mars previously. We model the atmosphere during solar minimum, mean, and maximum, and find that the deuterated ionosphere behaves similarly to the H-bearing ionosphere, but that non-thermal escape on the order of 8000-9000 cm$^{-2}$s$^{-1}$ dominates atomic D loss under all solar conditions. The total fractionation factor, $f$, is $f=0.04$--0.07, and integrated water loss is 147--158 m GEL. This is still less than geomorphological estimates. Deuterated ions at Mars are likely difficult to measure with current techniques due to low densities and mass degeneracies with more abundant H ions. Future missions wishing to measure the deuterated ionosphere in situ will need to develop innovative techniques to do so.Comment: 37 pages, 8 figures, published in Journal of Geophysical Research: Planet

Control of a Programmed Cell Death Pathway in Pseudomonas aeruginosa by an Antiterminator

In Pseudomonas aeruginosa the alp system encodes a programmed cell death pathway that is switched on in a subset of cells in response to DNA damage and is linked to the virulence of the organism. Here we show that the central regulator of this pathway, AlpA, exerts its effects by acting as an antiterminator rather than a transcription activator. In particular, we present evidence that AlpA positively regulates the alpBCDE cell lysis genes, as well as genes in a second newly identified target locus, by recognizing specific DNA sites within the promoter, then binding RNA polymerase directly and allowing it to bypass intrinsic terminators positioned downstream. AlpA thus functions in a mechanistically unusual manner to control the expression of virulence genes in this opportunistic pathogen

Age and diet shape the genetic architecture of body weight in diversity outbred mice.

Understanding how genetic variation shapes a complex trait relies on accurately quantifying both the additive genetic and genotype-environment interaction effects in an age-dependent manner. We used a linear mixed model to quantify diet-dependent genetic contributions to body weight measured through adulthood in diversity outbred female mice under five diets. We observed that heritability of body weight declined with age under all diets, except the 40% calorie restriction diet. We identified 14 loci with age-dependent associations and 19 loci with age- and diet-dependent associations, with many diet-dependent loci previously linked to neurological function and behavior in mice or humans. We found their allelic effects to be dynamic with respect to genomic background, age, and diet, identifying several loci where distinct alleles affect body weight at different ages. These results enable us to more fully understand and predict the effectiveness of dietary intervention on overall health throughout age in distinct genetic backgrounds

Nonthermal hydrogen loss at Mars: Contributions of photochemical mechanisms to escape and identification of key processes

Hydrogen loss to space is a key control on the evolution of the Martian atmosphere and the desiccation of the red planet. Thermal escape is thought to be the dominant loss process, but both forward modeling studies and remote sensing observations have indicated the presence of a second, higher-temperature "nonthermal" or "hot" hydrogen component, some fraction of which also escapes. Exothermic reactions and charge/momentum exchange processes produce hydrogen atoms with energy above the escape energy, but H loss via many of these mechanisms has never been studied, and the relative importance of thermal and nonthermal escape at Mars remains uncertain. Here we estimate hydrogen escape fluxes via 47 mechanisms, using newly-developed escape probability profiles. We find that HCO$^+$ dissociative recombination is the most important of the mechanisms, accounting for 30-50% of the nonthermal escape. The reaction CO$_2^+$ + H$_2$ is also important, producing roughly as much escaping H as momentum exchange between hot O and H. Total nonthermal escape from the mechanisms considered amounts to 39% (27%) of thermal escape, for low (high) solar activity. Our escape probability profiles are applicable to any thermospheric hot H production mechanism and can be used to explore seasonal and longer-term variations, allowing for a deeper understanding of desiccation drivers over various timescales. We highlight the most important mechanisms and suggest that some may be important at Venus, where nonthermal escape dominates and much of the literature centers on charge exchange reactions, which do not result in significant escape in this study.Comment: 47 pages, 4 figures, 3 tables. Accepted manuscript. An edited version of this paper was published by AG