Late Pliocene Ice-Rafted Debris Mass Accumulation Rates from IODP Site U1359, Wilkes Land Continental Rise, Antarctica

An assessment of sediments taken from the IODP (Integrated Ocean Drilling Program) Expedition 318, Core U1359A from the Wilkes Continental Land Rise, has been conducted at a high resolution to determine the response of the East Antarctic Ice Sheet to climate during the Late Pliocene. The section of core being studied dates back to ~3.7 to 2.7 million years ago (Ma). Studies can lead to an understanding of climate change in the future, from knowledge on how ice sheets have transformed in the past with similar atmospheric conditions to the present. Samples from this record were analyzed based on the bulk particle size distributions, which were determined using a Malvern Mastersizer 2000 laser diffractometer. The samples were treated to remove organics, opal, and biogenic carbonate. The data was then processed using the coarse fraction, grater than 125 microns to calculate ice rafted debris (IRD) mass accumulation rates (MAR). After analysis of IRD, an additional analysis of microtextures using a scanning electron microscope (SEM) was conducted on high peaks of IRD. This test confirmed that sediments were glacially derived. By comparing the IRD MAR record to temperature, sea level, C02 levels, d180 records, and seismic data, it was determined that peaks in IRD MAR coincide with an expanding ice sheet. The IRD record from Hole U1359A between 3.7 and 2.7 Ma reflects an IRD signal of ice sheet advance, with matching peaks and trends in other proxies

Mass Shootings and Mental Health Policy

Research suggests that mass shootings can increase mental health stigma, reinforce stereotypes that people with mental illness are violent, and influence public policy. This article examines mental health policy initiatives resulting from the mass shootings in Sandy Hook, Connecticut and Aurora, Colorado within the context of existing research about mental illness, suicide, substance abuse and gun violence. Previous legislation that restricts access to firearms among persons with mental illness is reviewed. The article suggests that gun control legislation that focuses on persons with mental illness is not supported by research, may create barriers to treatment, and may have limited efficacy in promoting public safety

Bound Flowers, Loose Leaves: Horticultural Form and Textual Practice in Early Modern English Print

The language of plants saturated the English print marketplace in the sixteenth and seventeenth centuries, as printers turned out an extraordinary number of instructional manuals on gardening and husbandry, retailing useful knowledge to a growing class of literate landowners and pleasure gardeners. In those same decades, increasing numbers of miscellanies were issued under titles drawn from the world of plants: poetical gardens, devotional nosegays, forests and bowers of practical wisdom. Bound Flowers, Loose Leaves examines these parallel trends as part of a single phenomenon. Against the unknowns of a new and expanding market, the horticultural processes evoked by these diverse texts naturalize the anonymous futures of print publication, situating the new adventure of print within that most ancient discipline of risk management: agriculture. This dissertation argues that these vegetable discourses fundamentally shaped how English readers understood the printed book. With remarkable frequency, printed books turned to a botanical idiom to describe their prodigious capacity to scatter, gather, and multiply, especially in the small literary forms of couplets, posies, and sentences. Showing how plant life became fundamental to how the world was imagined and known in print, I argue that the portability of these handles of knowledge, in Philip Sidney\u27s phrase, drove the production of both figurative language and natural knowledge in early modern England. In readings of popular instruction manuals and miscellanies as well as works by Isabella Whitney, George Gascoigne, Francis Bacon, and William Shakespeare, I show how these practical instructions and poetic figures organize a fictive reading public, imagined as dispersed consumers of scattered textual copies

Protein Phosphatase 1 at the Kinetochore Regulates Chromosome Segregation

Two regulatory mechanisms exist to ensure proper chromosome segregation in mitosis. First, improper kinetochore-microtubule attachments are destabilized through the error correction machinery. Second, the spindle assembly checkpoint (SAC) delays anaphase onset until all kinetochores have achieved bioriented microtubule attachments. Both of these mechanisms are mediated by several centromeric and kinetochore kinases, including Aurora B. Protein Phosphatase 1 (PP1) plays a counteracting role to Aurora B to stabilize kinetochore-microtubule attachments and silence the SAC. The regulation of PP1 to modulate these functions, however, remains enigmatic. Using the biochemical tools available in the Xenopus egg extract system, I show here that PP1 binds to the protein KNL1 (Spc105, Blinkin, CASC5) through an evolutionarily conserved RVxF motif. KNL1 is a member of the KMN network that forms the microtubule binding interface at the kinetochore. Using the genetic tools of Saccharomyces cerevisiae, I show that this interaction is essential for silencing the SAC, but has only a minimal effect on kinetochore-microtubule stability. Although phosphorylation of KNL1 by Aurora B can abrogate the KNL1- PP1 interaction, constitutive recruitment of PP1 by KNL1 is insufficient to prematurely silence the SAC. However, the amount of PP1 recruited to the kinetochore is tightly tuned, as targeting just one extra copy of PP1 to KNL1 is lethal. The data presented here leads to a model in which the KNL1-PP1 interaction acts to couple microtubule attachment with SAC signaling. Specific properties of the N-terminus of KNL1 may modulate this coupling, possibly though conformational changes upon microtubule attachment. In addition, there have been several other proteins found to recruit PP1 to the kinetochore, and how these regulatory subunits might cooperate to mediate the functions of PP1 will be discussed

Comparing Infrared Star-Formation Rate Indicators with Optically-Derived Quantities

We examine the UV reprocessing efficiencies of warm dust and polycyclic aromatic hydrocarbons (PAHs) through an analysis of the mid- and far-infrared surface luminosity densities of 85 nearby H$\alpha$-selected star-forming galaxies detected by the volume-limited KPNO International Spectroscopic Survey (KISS). Because H$\alpha$ selection is not biased toward continuum-bright objects, the KISS sample spans a wide range in stellar masses ($10^8$-$10^{12}\rm{M}_\odot$), as well as H$\alpha$ luminosity ($10^{39}$-$10^{43}\rm{ergs/s}$), mid-infrared 8.0$\mu$m luminosity ($10^{41}$-$10^{44}\rm{ergs/s}$), and [Bw-R] color (-.1-2.2). We find that mid-infrared polycyclic aromatic hydrocarbon (PAH) emission in the Spitzer IRAC 8.0$\mu$m band correlates with star formation, and that the efficiency with which galaxies reprocess UV energy into PAH emission depends on metallicity. We also find that the relationship between far-infrared luminosity in the Spitzer MIPS 24$\mu$m band pass and H$\alpha$-measured star-formation rate varies from galaxy to galaxy within our sample; we do not observe a metallicity dependence in this relationship. We use optical colors and established mass-to-light relationships to determine stellar masses for the KISS galaxies; we compare these masses to those of nearby galaxies as a confirmation that the volume-limited nature of KISS avoids strong biases. We also examine the relationship between IRAC 3.6$\mu$m luminosity and galaxy stellar mass, and find a color-dependent correlation between the two.Comment: 15 pages, 10 figure

The Arecibo Dual-Beam Survey: The HI Mass Function of Galaxies

We use the HI-selected galaxy sample from the Arecibo Dual-Beam Survey (Rosenberg & Schneider 2000) to determine the shape of the HI mass function of galaxies in the local universe using both the step-wise maximum likelihood and the 1/V_tot methods. Our survey region spanned all 24 hours of right ascension at selected declinations between 8 and 29 degrees covering ~430 deg^2 of sky in the main beam. The survey is not as deep as some previous Arecibo surveys, but it has a larger total search volume and samples a much larger area of the sky. We conducted extensive tests on all aspects of the galaxy detection process, allowing us to empirically correct for our sensitivity limits, unlike the previous surveys. The mass function for the entire sample is quite steep, with a power-law slope of \alpha ~ -1.5. We find indications that the slope of the HI mass function is flatter near the Virgo cluster, suggesting that evolutionary effects in high density environments may alter the shape of the HI mass function. These evolutionary effects may help to explain differences in the HI mass function derived by different groups. We are sensitive to the most massive sources (log M > 5x10^10 M\solar) over most of the declination range, \~1 sr, and do not detect any massive low surface brightness galaxies. These statistics restrict the population of Malin 1-like galaxies to <5.5x10^-6 Mpc^-3.Comment: ApJ accepted, 12 page