Mg II Absorption Characteristics of a Volume-Limited Sample of Galaxies at z ~ 0.1

We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey. We observed quasars near sightlines to 20 low-redshift (z ~ 0.1), luminous M_r <= -20.5 galaxies in SDSS DR4 and DR6 with the LRIS-B spectrograph on the Keck I telescope. The primary systematic criteria for the targeted galaxies are a redshift z >~ 0.1 and the presence of an appropriate bright background quasar within a projected 75 kpc/h of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong [EW(2796) >= 0.3 Ang.] Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong [EW(2796) >= 1-2 Ang] absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction f_c = 0.3-Angstrom absorbers at z ~ 0.1, even at impact parameters <= 35 kpc/h (f_c ~ 0.25). The data are consistent with a possible dependence of covering fraction and/or absorption halo size on the environment or star-forming properties of the central galaxy.Comment: accepted for publication in A

The Immigration Movement From 1880 to Present Day

Immigration is an important topic for today’s upper level high school student as it has bearing on Regents level exams and on today’s societal challenges as we address illegal immigration, its problems and solutions. The central question of this project is simply stated – what are the implications of web-based instruction in a high school history curriculum? In an effort to better equip students and educational peers, this three-part thesis project provides a comprehensive set of lessons on immigration in the United States and a section intended for website use. The first section examines US immigration from 1880-1925 and ranges in topic from the Chinese Exclusion Act to the Ku Klux Klan. The second section discusses Ellis Island through the current Mexican border debates. Responding to the reality of the classroom time constraints that exist in covering such a considerable topic, the third section posits the use of web-based instruction to enrich students’ experience and knowledge with US immigration history. This section evaluates the use of such web-based instruction while considering the various learning styles found in Differentiated Instruction, Gardner’s Multiple Intelligences, Bloom’s Taxonomy, and Piaget’s Stages of Development. It is suggested that this type of web-based instruction be intended for interactivity similar to collegiate level sites. Examples of web pages, lessons, and student worksheets are included

Coaching Families: A Focus on Nurturing and Responsive Relationships

The purpose of this session is to demonstrate the use of specific evidence-based family coaching strategies with a focus on supporting nurturing and responsive relationships. The presenter will introduce specific coaching strategies (e.g., performance-based feedback, video modeling, providing opportunities for practice), describe how and when to use the coaching strategy with families, and present several examples for using each coaching strategy with families. Participants will have opportunities to practice and plan for using the family coaching techniques

The WHIQII Survey: Metallicities and Spectroscopic Properties of Luminous Compact Blue Galaxies

As part of the WIYN High Image Quality Indiana Irvine (WHIQII) survey, we present 123 spectra of emission-line galaxies, selected on intermediate redshift (.4<z<.8) galaxies with blue colors that appear physically compact. The sample includes 15 true Luminous Compact Blue Galaxies (LCBGs) and an additional 27 slightly less extreme emission-line systems. These galaxies represent a highly evolving class that may play an important role in the decline of star formation since z~1, but their exact nature and evolutionary pathways remain a mystery. Here, we use emission lines to determine metallicities and ionization parameters, constraining their intrinsic properties and state of star formation. Some LCBG metallicities are consistent with a "bursting dwarf" scenario, while a substantial fraction of others are not, further confirming that LCBGs are a highly heterogeneous population but are broadly consistent with the intermediate redshift field. In agreement with previous studies, we observe overall evolution in the luminosity-metallicity relation at intermediate redshift. Our sample, and particularly the LCBGs, occupy a region in the empirical R23-O32 plane that differs from luminous local galaxies and is more consistent with dwarf Irregulars at the present epoch, suggesting that cosmic "downsizing" is observable in even the most fundamental parameters that describe star formation. These properties for our sample are also generally consistent with lying between local galaxies and those at high redshift, as expected by this scenario. Surprisingly, our sample exhibits no detectable correlation between compactness and metallicity, strongly suggesting that at these epochs of rapid star formation, the morphology of compact star-forming galaxies is largely transient.Comment: ApJ accepted, 17 pages, 20 figures, 2 tables (complete tables in published version

Understanding the Role of Transmembrane and Juxtamembrane Domains in Plexin and Neuropilin Signaling

Neuropilins (nrps) and plexins (plxns) are transmembrane (TM) proteins that form co-receptor complexes to guide neuronal, vascular, lymphatic, and bone development as well as cancer metastasis. While it is understood that nrp serves as the extracellular ligand-binding receptor and plxn as the signal-transducing portion of the complex, little is understood about the mechanism of activation of the signal transduction cascade beyond ligand binding. Understanding the mechanisms of plxn and nrp activation may provide insight necessary for rational design of novel cancer therapeutics.Co-receptor clustering is believed to induce activation. Previous studies suggest deletion of the plxn extracellular domain leads to a constitutively active plxn, but lack of membrane-anchorage of the cytosolic domain yields inactivity, implying a role for the plxn TM and juxtamembrane (JM) domains in clustering and subsequent activation. We demonstrate that a heptad repeat in the cytosolic JM domain modulates Danio rerio PlxnA3 homodimerization of the TM + JM domains in a bacterial membrane via the AraTM homodimer assay and of the TM + JM domains with a full extracellular domain intact via a bioluminescence resonance energy transfer (BRET2) assay. A specific mutation (M1281L) that enhances homodimerization in the BRET2 assay in the presence of a Nrp2a co-receptor and semaphorin-3F ligand also fails to rescue motor neuron patterning in PlxnA3-knockout zebrafish embryos, in contrast to the wild-type protein. We also demonstrate via these same techniques that a glycine-rich segment of the PlxnA3 TM domain modulates receptor homodimerization, competing with the dimerization motif of the JM domain. Specifically, mutations to small-x3-small motifs in the PlxnA3 TM domain enhance dimerization of the TM + JM domains in the AraTM assay. Mutations to both the TM and JM dimerization motifs demonstrate, in the context of the TM + JM system, the heptad repeat in the JM dominates TM + JM dimerization. Mutations to the small-x3-small TM dimerization motifs exhibit reduced functionality in the zebrafish embryo axonal guidance assay. Collectively, these results demonstrate that enhanced PlxnA3 dimerization does not correlate with enhanced function. The TM-driven dimerization serves to weaken the JM dimer, likely allowing switchability between co-receptors as well as active and inactive states.The nrp MAM domain is also believed to contribute to the observed clustering phenomenon with the intact, full-length plxn receptor. We show that cysteines in the Danio rerio Nrp2a MAM domain, in particular residue C711, modulate Nrp2 homodimerization, as determined via the BRET2 assay. Mutation of residue C711 also disrupts ligand binding. While zebrafish embryos injected with wild-type nrp2a RNA exhibit ectopic vascular branching, significantly fewer embryos injected with nrp2a RNA with the C711S mutation exhibit this overexpression phenotype.Collectively, this work provides insight into the dimerization mechanisms important for nrp and plxn activity. The structure-function correlations determined may assist in rational design of targeted therapeutics to alter nrp and plxn activity

Possible Local Spiral Counterparts to Compact Blue Galaxies at Intermediate Redshift

We identify nearby disk galaxies with optical structural parameters similar to those of intermediate-redshift compact blue galaxies. By comparing HI and optical emission-line widths, we show that the optical widths substantially underestimate the true kinematic widths of the local galaxies. By analogy, optical emission-line widths may underrepresent the masses of intermediate-z compact objects. For the nearby galaxies, the compact blue morphology is the result of tidally-triggered central star formation: we argue that interactions and minor mergers may cause apparently compact morphology at higher redshift.Comment: 5 pages, uses emulateapj5 and psfig. To appear in ApJ

Environments of Redshift Survey Compact Groups of Galaxies

Redshift Survey Compact Groups (RSCGs) are tight knots of N >= 3 galaxies selected from the CfA2+SSRS2 redshift survey. The selection is based on physical extent and association in redshift space alone. We measured 300 new redshifts of fainter galaxies within 1 h^{-1} Mpc of 14 RSCGs to explore the relationship between RSCGs and their environments. 13 of 14 RSCGs are embedded in overdense regions of redshift space. The systems range from a loose group of 5 members to an Abell cluster. The remaining group, RSCG 64, appears isolated. RSCGs are isolated and distinct from their surroundings to varying degrees, as are the Hickson Compact Groups. Among the 13 embedded RSCGs, 3 are distinct from their general environments (RSCG 9, RSCG 11 and RSCG 85).Comment: 35 pages, including 10 figures and 5 tables, accepted for publication in the Astronomical Journa

Water and Climate Risks Facing U.S. Corn Production: How Companies and Investors Can Cultivate Sustainability

U.S. corn farmers are among the most productive in the world, generating a record harvest of nearly 14 billion bushels in 2013 -- enough corn to fill a freight train long enough to circle the Earth. This production supports a mammoth agricultural sector comprised not just of farmers, but also major food, meat and energy companies that have an enormous stake in the long-term productivity and resilience of American agriculture. However, in the face of this bounty, three major threats to U.S. corn production loom: climate change, unsustainable water use and inefficient and damaging fertilizer practices.Ceres' new report analyzes the risks facing U.S. corn production. The report provides recommendations for how corn-buying companies and their investors can catalyze more sustainable agricultural practices, while helping farmers preserve and enhance yields, and protect precious water resources. The research is accompanied by new data and interactive maps that highlight irrigation risks and fertilizer pollution hotspots