Sharing Books and Stories: Book Clubs That Book Talk

“When does the book club start?” a student asks as he passes me in the hall. “It begins during Teen Read Week in October,” I reply. He replies, “Aww…that long?” I get this almost every day throughout September. I have often thought of changing the beginning date for my book club, but then it fits in so well with the purpose of the American Library Association’s Teen Read Week which occurs in October

Metabolism, Consumption Rates, and Scope for Growth of Porcelain Crab (Petrolisthes galathinus)

Porcelain crabs Petrolisthes galathinus (Bosc, 1802) can be found at high densities in oyster reefs. To examine effects of diet on metabolism, crabs (N = 32) were fed Artemia salina nauplii, mixed microalgae, or algal biofilm extract, or left unfed. Oxygen consumption, ammonia excretion, food consumption rate, and absorption efficiency were determined and scope for growth (SFG) was calculated. Oxygen consumption and food consumption rates were highest in crabs fed Artemia. The energy gained from mixed microalgae (47 ± 143 J h-1) and algal biofilm (265 ± 203 J h-1) was less than the energy gained from Artemia (9,963 ± 658 J h-1). Energy expenditures (oxygen consumption and ammonia excretion) suggest that P. galathinus has a low cost of routine metabolism and is able to consume a broad range of food resources including microalgae, benthic algae, and zooplankton. Consumption rates and SFG suggest that zooplankton, when present, are an important and valuable food source for porcelain crabs

Effects of Black Mangrove (Avicennia germinans) Expansion on Saltmarsh (Spartina alterniflora) Benthic Communities of the South Texas Coast

This study examined the effects of mangrove expansion on benthic communities. This was accomplished by examining plant composition, benthic community composition, and belowground root biomass. Two sites were examined: Corpus Christi Pass, Corpus Christi, TX where mangroves have become more common in the last decade and the Lower Laguna Madre, South Padre Island, TX where mangroves are well established. This research seeks to provide preliminary results to provide direction for future studies examining the interplay of S. alterniflora and A. germinans habitat on benthic communities. We hypothesize that the more established site of South Padre Island will have greater numbers of species than the newer communities of Corpus Christi, and that A. germinans habitats will have lower diversity of infaunal organisms than S. alterniflora habitats

Using Simulated Micrometeoroid Impacts to Understand the Progressive Space Weathering of the Surface of Mercury

The surfaces of airless bodies such as Mercury are continually modified by space weathering, which is driven by micrometeoroid impacts and solar wind irradiation. Space weathering alters the chemical composition, microstructure, and spectral properties of surface regolith. In lunar and ordinarychondritic style space weathering, these processes affect the reflectance properties by darkening (lowering of reflectance), reddening (increasing reflectance with increasing wavelength), and attenuation of characteristic absorption features. These optical changes are driven by the production of nanophase Febearing particles (npFe). While our understanding of these alteration processes has largely been based on data from the Moon and near-Earth S-type asteroids, the space weathering environment at Mercury is much more extreme. The surface of Mercury experiences a more intense solar wind flux and higher velocity micrometeoroid impacts than its planetary counterparts at 1 AU. Additionally, the composition of Mercurys surface varies significantly from that of the Moon. Most notably, a very low albedo unit has been identified on Mercurys surface, known as the low reflectance material (LRM). This unit is enriched with up to 4 wt.% carbon, likely in the form of graphite, over the local mean. In addition, the surface concentration of Fe across Mercurys surface is low (<2 wt.%) compared to the Moon. Our understanding of how these low-Fe and carbon phases are altered as a result of space weathering processes is limited. Since Fe plays a critical role in the development of space weathering features on other airless surfaces (e.g., npFe), its limited availability on Mercury may strongly affect the space weathering features in surface materials. In order to understand how space weathering affects the chemical, microstructural, and optical properties of the surface of Mercury, we can simulate these processes in the laboratory [7]. Here we used pulsed laser irradiation to simulate the short duration, high temperature events associated with micrometeoroid impacts. We used forsteritic olivine, likely present on the Mercurian surface, with varying FeO contents, each mixed with graphite, in our experiments. We then performed reflectance spectroscopy and electron microscopy to investigate the spectral, chemical, and microstructural changes in these samples

Shock physics code research at Sandia National Laboratories; massively parallel computers and advanced algorithms

Shock physics researchers at Sandia are working in two areas: massively parallel computing and improved solution algorithms. Our goal is predictive modeling of large, three-dimensional problems. We will discuss the goals, rationale and status of this work

John Donne's two anniversaries

This thesis treats three major problems in John Donne's Two Anniversaries! the subject of the two poems, the themes and structure, and Donne's references to Scholastic natural philosophy and to new science. The latter half of the thesis examines the poet's references to Scholastic thought and to the revolutionary scientific work of his contemporaries in order to determine his reaction to the two conflicting explanations of phenomena. The complexity of the twin poems is immediately evident. This is the primary point of agreement among those who have studied the Two Anniversaries. The first problem which is examined—the question of the subject has been variously resolved. Previous works have interpreted the subject as Astraea, goddess of Justice, Queen Elizabeth I, Christ, and the Virgin Mary. The poems were written as a tribute to Elizabeth Drury after the girl's father hired Donne to memoralize her in verse when she died. This thesis contends that Elizabeth Drury is indeed one subject of the poems. But since Donne never knew the girl personally, he was forced at points in the work to describe more famous women, actual or legendary, with whom he was more familiar in order to produce the two long poems. The evidence that in sections of the poems the subject being described is Astraea and Elizabeth I is considerable, and Chapter One of this thesis concludes that the subject is pluralistic

The Development and Application of Massively Parallel Solid Mechanics Codes

Computational physicists at Sandia National Laboratories have moved the Eulerian CTH code, and the arbitrary-Lagrangian-Eulerian ALEGRA code to distributed memory parallel computers. CTH is a three-dimensional solid mechanics code used for large-deformation, shock wave analysis. ALEGRA is a three-dimensional arbitrary Lagrangian-Eulerian solid-mechanics code used for coupled large-deformation, shock and structural mechanics problems. This paper discusses our experiences moving the codes to parallel computers, the algorithms we used and our experiences running the codes

Fragment properties at the catastrophic disruption threshold: The effect of the parent body's internal structure

Numerical simulations of asteroid break-ups, including both the fragmentation of the parent body and the gravitational interactions between the fragments, have allowed us to reproduce successfully the main properties of asteroid families formed in different regimes of impact energy, starting from a non-porous parent body. In this paper, using the same approach, we concentrate on a single regime of impact energy, the so-called catastrophic threshold usually designated by Q*D, which results in the escape of half of the target's mass. Thanks to our recent implementation of a model of fragmentation of porous materials, we can characterize Q*D for both porous and non-porous targets with a wide range of diameters. We can then analyze the potential influence of porosity on the value of Q*D, and by computing the gravitational phase of the collision in the gravity regime, we can characterize the collisional outcome in terms of the fragment size and ejection speed distributions, which are the main outcome properties used by collisional models to study the evolutions of the different populations of small bodies. We also check the dependency of Q*D on the impact speed of the projectile. In the strength regime, which corresponds to target sizes below a few hundreds of meters, we find that porous targets are more difficult to disrupt than non-porous ones. In the gravity regime, the outcome is controlled purely by gravity and porosity in the case of porous targets. In the case of non-porous targets, the outcome also depends on strength. We then propose some power-law relationships between Q*D and both target's size and impact speed that can be used in collisional evolution models.Comment: 18 pages, 19 Figures. Accepted for publication in Icaru