Estimating the Number of Essential Genes in a Genome by Random Transposon Mutagenesis

We describe a Bayesian method for estimating the number of essential genes in a genome, on the basis of data on viable mutants for which a single transposon was inserted after a random TA site in a genome,potentially disrupting a gene. The prior distribution for the number of essential genes was taken to be uniform. A Gibbs sampler was used to estimate the posterior distribution. The method is illustrated with simulated data. Further simulations were used to study the performance of the procedure

Life in the Trenches: The Archeological Investigation of the Federal Picket Line near the Crater, Petersburg National Battlefield

Archeologists from the University of Maryland conducted an excavation of the Federal picket line within Petersburg National Battlefield as part of the Overview and Assessment of archeological resources within the battlefield's Main Unit. The goal of the Overview and Assessment is to provide basic background information on the archeological resources within the battlefield park. This includes, describing the area's environmental and culture history; list, describe, and evaluate known archeological resources; describe the potential for as-yet- unidentified archeological resources; outline relevant research topics; and provide recommendations for future research. As part of the Overview and Assessment project, National Park Service staff and University of Maryland archeologists agreed that part of the project should provide a public component. To help further both goals of evaluating archeological resources and public visibility, project directors decided to explore the archeological potential of the Federal picket line near the Crater. The Federal picket line, in this area of the battlefield, played a vital role in the Battle of the Crater on July 30, 1864. The picket line also served as a key area because of its proximity, 100 yards, from the Confederate defenses. This was one of the closest points between the two armies. This report contains details from the excavation and public interpretation portions of the project. Excavation details focus on the data recovered from the four excavation units used to bisect the picket trench. Archeologists were able to excavate and record a seven foot section of the Federal picket trench, and features associated with the Battle of the Crater. Archeological features and data also provide details on the post-war filling and history of the picket trench area. Artifacts recovered from the trench, including pieces of preserved canvas, leather, tin cups, ink well fragments, food tins, and other militaria, provide clues to the daily lives of soldiers posted in the trench. Details on the public interpretation portion include information on the development, methodology, and success of the major components of the public program. These details, including descriptions of the project website, tour brochures, exhibits, and site tours, provide a template for future archeology interpretative programs

Investigation of Substituted-Benzene Dopants for Charge Exchange Ionization of Nonpolar Compounds by Atmospheric Pressure Photoionization

Atmospheric pressure photoionization (APPI) using a dopant enables both polar and nonpolar compounds to be analyzed by LC/MS. To date, the charge exchange ionization pathway utilized for nonpolar compounds has only been efficient under restrictive conditions, mainly because the usual charge exchange reagent ions—the dopant photoions themselves—tend to be consumed in proton transfer reactions with solvent and/or dopant neutrals. This research aims to elucidate the factors affecting the reactivities of substituted-benzene dopant ions; another, overriding, objective is to discover new dopants for better implementing charge exchange ionization in reversed-phase LC/MS applications. The desirable properties for a charge exchange dopant include low reactivity of its photoions with solvent and dopant neutrals and high ionization energy (IE). Reactivity tests were performed for diverse substituted-benzene compounds, with substituents ranging from strongly electron withdrawing (EW) to strongly electron donating (ED). The results indicate that both the tendency of a dopant's photoions to be lost through proton transfer reactions and its IE depend on the electron donating/withdrawing properties of its substituent(s): ED groups decrease reactivity and IE, while EW groups increase reactivity and IE. Exceptions to the reactivity trend for dopants with ED groups occur when the substituent is itself acidic. All told, the desirable properties for a charge exchange dopant tend towards mutual exclusivity. Of the singly-substituted benzenes tested, chloro- and bromobenzene provide the best compromise between low reactivity and high IE. Several fluoroanisoles, with counteracting EW and ED groups, may also provide improved performance relative to the established dopants

African Americans and Appomattox Manor Within the Structured Landscape of the Eppes Plantation

The Civil War brought about many changes in Virginian society, including the area around City Point, Virginia. These changes greatly effected the manner in which plantation owners managed their farms. Plantation owners had to find new ways of obtaining and exploiting their labor, and protecting their resources. The goal of this report is to explore those changes between the years 1851 and 1872 on the Eppes' plantations. I examine how Dr. Eppes structured his landscape to aid in controlling his productive resources, and the relationship he held with African-Americans. Part of exploring that relationship will be examining the living conditions of African-Americans on the Eppes' plantations as slaves and freedmen laborers. Dr. Eppes' home, Appomattox Manor, and its grounds now make up the City Point Unit of the Petersburg National Battlefield. This report will place the City Point Unit into its larger historic context. Though the unit is best known as the location of General Grant's headquarters during the Siege of Petersburg, its history is far more extensive. In this report, I place City Point and Appomattox Manor in the plantation context which surrounded them before and after the war. It will show how the Civil War was not an isolated event, but was effected by and affected the social world around it

Possible Detection of OVI from the LMC Superbubble N70

We present FUSE observations toward four stars in the LMC superbubble N70 and compare these spectra to those of four comparison targets located in nearby field and diffuse regions. The N70 sight lines show OVI 1032 absorption that is consistently stronger than the comparison sight lines by ~60%. We attribute the excess column density (logN_OVI=14.03 cm^-2) to hot gas within N70, potentially the first detection of OVI associated with a superbubble. In a survey of 12 LMC sight lines, Howk et al. (2002a) concluded that there was no correlation between ISM morphology and N_OVI. We present a reanalysis of their measurements combined with our own and find a clear difference between the superbubble and field samples. The five superbubbles probed to date with FUSE show a consistently higher mean N_OVI than the 12 non-superbubble sight lines, though both samples show equivalent scatter from halo variability. Possible ionization mechanisms for N70 are discussed, and we conclude that the observed OVI could be the product of thermal conduction at the interface between the hot, X-ray emitting gas inside the superbubble and the cooler, photoionized material making up the shell seen prominently in Halpha. We calculate the total hydrogen density n_H implied by our OVI measurements and find a value consistent with expectations. Finally, we discuss emission-line observations of OVI from N70.Comment: 9 pages in emulateapj style. Accepted to Ap

The Gamma-Ray Blazar Content of the Northern Sky

Using survey data, we have re-evaluated the correlation of flat spectrum radio sources with EGRET sources in the Northern sky. A likelihood analysis incorporating the radio and X-ray properties and the Gamma-ray source localization is used to gauge the reliability of associations and to search for counterparts of previously unidentified EGRET sources. Above |b|=10deg, where the classification is complete, we find that 70% of the Northern EGRET sources have counterparts similar to the bright EGRET blazars. For several of these we identify known blazar counterparts more likely than the earlier proposed 3EG association; for ~20 we have new identifications. Spectroscopic confirmation of these candidates is in progress and we have found flat spectrum radio quasars and BL Lac counterparts with redshifts as high as 4. We also find strong evidence for a set of 28 objects with no plausible counterpart like the known EGRET Blazars. These thus represent either a new extragalactic population or a population of Galactic objects with a large scale height. The survey has been extended into the plane, where we find several new blazar candidates; the bulk of the sources are, however, Galactic. Looking ahead to the GLAST era we predict that several of the present 3EG sources are composite and that higher resolution data will break these into multiple Blazar IDs.Comment: 13 pages, 6 figures, submitted to Ap

Large Magellanic Cloud Planetary Nebula Morphology: Probing Stellar Populations and Evolution

Planetary Nebulae (PNe) in the Large Magellanic Cloud (LMC) offer the unique opportunity to study both the Population and evolution of low- and intermediate-mass stars, by means of the morphological type of the nebula. Using observations from our LMC PN morphological survey, and including images available in the HST Data Archive, and published chemical abundances, we find that asymmetry in PNe is strongly correlated with a younger stellar Population, as indicated by the abundance of elements that are unaltered by stellar evolution (Ne, Ar, S). While similar results have been obtained for Galactic PNe, this is the first demonstration of the relationship for extra-galactic PNe. We also examine the relation between morphology and abundance of the products of stellar evolution. We found that asymmetric PNe have higher nitrogen and lower carbon abundances than symmetric PNe. Our two main results are broadly consistent with the predictions of stellar evolution if the progenitors of asymmetric PNe have on average larger masses than the progenitors of symmetric PNe. The results bear on the question of formation mechanisms for asymmetric PNe, specifically, that the genesis of PNe structure should relate strongly to the Population type, and by inference the mass, of the progenitor star, and less strongly on whether the central star is a member of a close binary system.Comment: The Astrophysical Journal Letters, in press 4 figure

The acute and delayed effects of foam rolling duration on male athlete’s flexibility and vertical jump performance

© 2022 The Authors. Published by International Universities Strength and Conditioning Association. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.47206/ijsc.v2i1.90Foam rolling (FR) durations totaling ≤60 s per muscle are reported to acutely increase flexibility and vertical jump performance. However, limited research has investigated whether these benefits can outlast the inactive post-warmup preparatory period that typically separates warmups from the start of sporting competition. Eleven male athletes (height 1.77 0.09 m, body mass 78.0 17.0 kg, age 22 2 years) completed familiarization, followed by three experimental trials in a randomized and counterbalanced repeated measures crossover design. Trials commenced with 5 min jogging, before ankle dorsiflexion range of motion (ADF-ROM), sit and reach (S&R), countermovement jump (CMJ) and squat jump (SJ) baseline testing. Participants then sat inactively for 10 min (control) or performed lower extremity FR totaling either 30 (30FR) or 60 s (60FR) that targeted four agonist-antagonist leg muscles. Testing was then repeated before and after a simulated inactive 15 min post-warmup preparatory period to establish the acute and delayed effects of FR on performance. A two-way repeated measures analysis of variance was used to identify any significant interaction effects between conditions (30FR, 60FR, control) and timepoint (baseline, acute, delayed). No significant condition x timepoint interaction effect was detected for the ADF-ROM (f = 1.63, p = 0.19), S&R (f = 0.80, p = 0.54), CMJ ((f = 0.83, p = 0.99) or SJ (f = 0.66, p = 0.99). Therefore, FR totaling ≤60 s appears insufficient to enhance flexibility or vertical jump performance in male athletes