Differential chemical abundance analysis of a 47 Tuc AGB star with respect to Arcturus

This study resolves a discrepancy in the abundance of Zr in the 47 Tucanae asymptotic giant branch star Lee 2525. This star was observed using the echelle spectrograph on the 2.3 m telescope at Siding Spring Observatory. The analysis was undertaken by calibrating Lee 2525 with respect to the standard giant star Arcturus. This work emphasises the importance of using a standard star with stellar parameters comparable to the star under analysis rather than a calibration with respect to the Sun (Koch & McWilliam 2008). Systematic errors in the analysis process are then minimised due to the similarity in atmospheric structure between the standard and programme stars. The abundances derived for Lee 2525 were found to be in general agreement with the Brown & Wallerstein (1992) values except for Zr. In this study Zr has a similar enhancement ([Zr/Fe] = +0.51 dex) to another light s-process element, Y ([Y/Fe] = +0.53 dex), which reflects current theory regarding the enrichment of s-process elements by nuclear processes within AGB stars (Busso et al. 2001). This is contrary to the results of Brown & Wallerstein (1992) where Zr was under-abundant ([Zr/Fe] = +0.51 dex) and Y was over-abundant ([Y/Fe] = +0.50 dex) with respect to Fe.Comment: 11 pages, 5 figures Accepted for publication in MNRA

Ivory, Elephants, and Men (A Book Soon To Be Published)

Topical preview of the titular tome

The Vitamin B Complex and Fasting Blood-Sugar Levels: An Investigation into the Changes in Fasting Blood-Sugar Levels of Diabetic and Non-diabetic Patients Following the Intravenous Injection of Aneurin, Riboflavin and Nicotinamide, with a Review of Relevant Literature, and a Note on Diabetic Neuritis

In the writer's own investigations, aneurin, riboflavin and nicotinamide were administered separately and together to diabetic and non-diabetic patients. No significant changes occurred in the blood-sugar levels during the three hours following administration. Many of the previous, more favourable reports were based on inadequately controlled experiments with too small numbers of cases. In some reports, the accuracy of the biochemical work was questionable. The main drawback of the present investigations is that the number of diabetics tested is still too small. Precautions were taken to verify any marked changes in the blood-sugar levels, to exclude the possibility that they were due to inaccuracies in the biochemical estimations. It is now becoming fairly clear that while various factors in the vitamin B complex play important parts in the metabolism of carbohydrates, it is not likely that any of them could take the place of, or increase the effect of insulin. There is also no definite evidence that an increased need of the vitamins exists in uncomplicated diabetes. Vitamin B therapy is therefore not necessary in the routine treatment of diabetes. But it is also now becoming more generally recognised that vitamin B supplements are useful in many complications of diabetes, such as infections, parenteral feeding and old age. Opinions are now more prevalent that very few, if any, cases of diabetic neuritis are due to aneurin deficiency. In the absence of any other definite cause, however, it seems that intensive and prolonged aneurin therapy is still worthy of trial in diabetic neuritis

Bolide impact effects on the West Florida Platform, Gulf of Mexico: end Cretaceous and late Eocene

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Poag, C. W. Bolide impact effects on the West Florida Platform, Gulf of Mexico: end Cretaceous and late Eocene. Geosphere, 18(3), (2022): 1077–1103, https://doi.org/10.1130/GES02472.1.This study documents seismic reflection evidence that two different bolide impacts significantly disrupted stratigraphic and depositional processes on the West Florida Platform (Gulf of Mexico). The first impact terminated the Late Cretaceous Epoch (Chicxulub impact, Mexico; ca. 66 Ma; end-Maastrichtian age). The second took place in the late Eocene (Chesapeake Bay impact, Virginia, USA, portion of the Chesapeake Bay; ca. 35 Ma; Priabonian age). Both impacts produced far-reaching seismic shaking and ground roll followed by an impact-generated tsunami, the effects of which are evident in the seismostratigraphic record. The Chicxulub seismic shaking caused collapse and shoreward retreat of the Florida Escarpment and widely disrupted (faulting, folding, slumping) normal flat-lying shelf beds. The associated tsunami currents redistributed these shelf deposits and mixed them together with collapse debris from the escarpment to form a thick wedge of sediments along the base of the escarpment. The Chesapeake Bay impact created a mounded sedimentary deposit near the outer edge of the late Eocene ramp slope. This deposit also has a bipartite origin. A lower layer is marked by en echelon faulting created in situ by seismic shaking, whereas an upper layer represents sediments redistributed from the late Eocene shelf and upper ramp slope by tsunami-driven bottom currents (debris flows, contour currents, slumps). This is the first report of seismic effects from the Chesapeake Bay impact in the Gulf of Mexico. These results further demonstrate that large-scale marine bolide impacts have widespread effects on the stratigraphic and depositional record of Earth.I am grateful to the following persons for their assistance in this research: Matt Arsenault for help attaining seismic data; T.J. Christian for providing samples from the Texaco 2523-1 borehole; Deborah Hutchinson, David Foster, Christian Koeberl, and an unnamed reviewer for helpful reviews of the original manuscript; and especially to the U.S. Geological Survey for supporting my continued research as a Scientist Emeritus

Ivory, Elephants, and Man: A Survey

It is well known that elephants face two basic threats to their existence. One is the fact that they bear large tusks, the primary source of ivory since prehistoric times. The other is that their natural habitats are being destroyed by human expansion. While the latter problem is at least being temporarily staved off in certain regions by the creation and expansion of sanctuaries, the ivory problem seems to defy rational solution even in protected areas, especially in Africa. This problem is neither so simple as it appears, nor is it a recent phenomenon. The roots go back to the beginning of civilization and beyond. Certain paradoxes apparently implicit in the history of the ivory trade, and in man\u27s long-term association with elephants, can be explained in the framework of various bioeconomic correlations and in terms of man\u27s own evolutionary heritage. The implications of biology and history do not necessarily predicate contradiction, confusion, and extinction. A proper comprehension of the ivory trade is essential to any organized solution

Fluctuation Induced Instabilities in Front Propagation up a Co-Moving Reaction Gradient in Two Dimensions

We study 2D fronts propagating up a co-moving reaction rate gradient in finite number reaction-diffusion systems. We show that in a 2D rectangular channel, planar solutions to the deterministic mean-field equation are stable with respect to deviations from planarity. We argue that planar fronts in the corresponding stochastic system, on the other hand, are unstable if the channel width exceeds a critical value. Furthermore, the velocity of the stochastic fronts is shown to depend on the channel width in a simple and interesting way, in contrast to fronts in the deterministic MFE. Thus, fluctuations alter the behavior of these fronts in an essential way. These affects are shown to be partially captured by introducing a density cutoff in the reaction rate. Some of the predictions of the cutoff mean-field approach are shown to be in quantitative accord with the stochastic results

The fixation probability of rare mutators in finite asexual populations

A mutator is an allele that increases the mutation rate throughout the genome by disrupting some aspect of DNA replication or repair. Mutators that increase the mutation rate by the order of 100 fold have been observed to spontaneously emerge and achieve high frequencies in natural populations and in long-term laboratory evolution experiments with \textit{E. coli}. In principle, the fixation of mutator alleles is limited by (i) competition with mutations in wild-type backgrounds, (ii) additional deleterious mutational load, and (iii) random genetic drift. Using a multiple locus model and employing both simulation and analytic methods, we investigate the effects of these three factors on the fixation probability $P_{fix}$ of an initially rare mutator as a function of population size $N$, beneficial and deleterious mutation rates, and the strength of mutations $s$. Our diffusion based approximation for $P_{fix}$ successfully captures effects (ii) and (iii) when selection is fast compared to mutation ($\mu/s \ll 1$). This enables us to predict the conditions under which mutators will be evolutionarily favored. Surprisingly, our simulations show that effect (i) is typically small for strong-effect mutators. Our results agree semi-quantitatively with existing laboratory evolution experiments and suggest future experimental directions.Comment: 46 pages, 8 figure

Schiaparelli\u27s Shooting Stars

The fundamental work on this translation was done by Miss Francis M. Svaldi, a student working on National Youth Administration funds. After Miss Svaldi\u27s graduation, her work was revised and corrected by James R. Naiden, Special Research Assistant in Astronomy (now 1st Lieutenant Army Air Corps), working under the direction of C. C. Wylie, Professor of Astronomy. The pressure of war work, and the enlistment of Mr. Naiden in the Armed Forces, have made it impossible to smooth out the translation as planned. However, it has been thought best to publish it in its present form, since it is not known when further work will be possible. The language of Schiaparelli is unusually full, and very precise. In this translation, such a precision would have appeared exaggerated, and an occasional word or phrase has been omitted to enhance clarity