Increasing Returns to Education and Progress towards a College Degree

Returns to college have increased, but graduation rates have changed relatively little. Modifying a human capital model of college enrollment to endogenize time-to-graduation, we predict that higher returns to education will both speed graduation and increase enrollment. Some of those new entrants may, however, take longer to graduate. Using the 1989 and 1995 Beginning Postsecondary Studies, we employ a multinomial logit to model the association between individual and family characteristics, and five-year college outcomes: graduation, continued enrollment, and non-enrollment. Between cohort differences arise either because the characteristics of those entering college are different or because the relations between characteristics and outcomes have changed. We utilize a Oaxaca-Blinder style decomposition to distinguish between these two alternatives, attributing differences in characteristics to newly attracted students and differences in the relations between characteristics and outcomes to historically attracted students behaving differently. It is changes in behavior that explain the increased progress we observe.Higher Education, Graduation Rates, Persistence

Reported Progress under the Student Right-to-Know Act: How Reliable is It?

The Student Right-to-Know Act requires colleges to provide institution-specific information on graduation rates for students initially enrolling full-time in the fall term. Not all students enroll in that fashion, especially at two-year institutions. We use data on degree-seeking students from the 1996/2001 Beginning Post-Secondary Survey to identify students for whom statistics are and are not reportable under the Act and to track their progress. Results indicate the published progress rates are substantially higher than the progress rates for the non-reportable populations, whether students enter a two-year or a four-year institution. While progress rates for the two samples are significantly correlated within four-year institutions, they are not within two-year institutions. For those beginning at two-year institutions, the progress rates reported under the Student Right-to-Know Act are indicative of neither their absolute nor their relative (cross-institution) probability of success. Policy makers and prospective students will not make efficient decisions without better information.Efficiency, Resource Allocation, Graduation

The Size Relationship of 12 Days Post-Exodus Larvae with 56 Day Post-Exodus Fingerlings Regarding Growth and Survival in Bluegill (Lempomis macrochirus)

Low survival and quality of early life-stage bluegill is an obstacle to viable production where size may influence weaning efficiency. Herein, we investigate through two trials the effects of fry size 12-d post-exodus on total length, weight, production and survival through 56-d post-exodus. Full sibling broods (trial 1=10, trial 2=6) were reared with feedings of brine shrimp Artemia sp. nauplii (BS) through 12-d post-exodus (PE). Broods of trial 1 were visual sorted 12 d PE into small and large size groups. Fry (n = 25) from each size group were sampled for measured total length (TL) and weight. Starting 14 d PE, a 7-d co-feeding period with a commercial dry feed (#0 crumb) that was continued through 27 d PE with subsequent feedings using a larger version (#1 crumb) of the same diet continuing through 56 d PE (trial end). Broods of trial 2 were split 4 d post-conception into two gorups of pro-larvae (n = 400). Slow growing groups were fed hourly 0800-1700 while fast growing were fed additionally at 0400 and 2200 through 12 d PE. Surviving fish from each size gorup were collected, with random samples (n = 25 fish) measured for TL and weight. Fry (n = 100 where possible) were placed into 151-L aqauriums with slow and fast growing feed regimens maintained through 13-d PE. Culture regimen thereafter was same as trial 1. Fish of both trials were harvested, measured for TL, weight, and survival. The Wilcoxon Signed Rank Test was run one-tailed using SAS. Results of trial 1 indicate size at 12 d was a predictor of TL, weight and survival through 56 d PE (p ≤ 0.156). Size variation at 12 d as a function of genetics is a predictor of growth and survival through 56 d while at least some size variation resulting from early growth rate differences can be overcome by compensatory growth.https://bluetigercommons.lincolnu.edu/lucer-pubs/1007/thumbnail.jp

Uptake of dissolved inorganic and organic bphosphorus compounds by phytoplankton and bacterioplankton

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109807/1/lno19923720232.pd

Amino Acid Profiles in the Tissues of Juvenile Bluegill (Lepomis Macrochirus) from the Wild and Commercially-fed Fish

Amino acid profiles of fish tissues and fish eggs have been extensively investigated in some fish species. Amino acid profiles are helpful in quantifying the indispensable amino acid requirements for these fish. Bluegill is a major forage fish for the largemouth bass (Micropterus samoides) and an important recreational fish throughout the US. The demand for bleugill as a food fish has increased recently. However, the information on the amino acid profiles of its eggs and tissues is lacking. The objectve of this study was to determine the amino acid profiles of the muscles and whole body of the 1-2 g wild and the commercially fed bluegill. Wild fish were obtained from the ponds that relied on the natural food source. Commercially fed fish were grown indoors. Skinless muscles were obtained by dissected both sides of the 1-2 g bluegill. The results showed the lysine was the most abundant indispensable amino acids in muscles and hwole body of both the wild and the farm-raised fish. The proportion of an individual indispensable amino acid to the sum of all detectable amino acids amount was similar for whole body and muscles in wild or raised fish. For whole body or muscle tissue, wild fish contained significantly higher crude protein but lower crude lipid levels than farm-raised bluegill (p\u3c0.05). This study suggested that nutritional history affected tissue proximate compositions.https://bluetigercommons.lincolnu.edu/lucer-pubs/1003/thumbnail.jp

A Predicted Correlation Between Age Gradient and Star Formation History in FIRE Dwarf Galaxies

We explore the radial variation of star formation histories in dwarf galaxies simulated with Feedback In Realistic Environments (FIRE) physics. The sample contains 9 low-mass field dwarfs with M_ star = 10^5 - 10^7 M_sun from previous FIRE results, and a new suite of 17 higher mass field dwarfs with M_star = 10^7 - 10^9 M_sun introduced here. We find that age gradients are common in our dwarfs, with older stars dominant at large radii. The strength of the gradient correlates with overall galaxy age such that earlier star formation produces a more pronounced gradient. The relation between formation time and strength of the gradient is driven by both mergers and star-formation feedback. Mergers can both steepen and flatten the age gradient depending on the timing of the merger and star formation history of the merging galaxy. In galaxies without significant mergers, early feedback pushes stars to the outskirts at early times. Interestingly, among galaxies without mergers, those with large dark matter cores have flatter age gradients because these galaxies have more late-time feedback. If real galaxies have age gradients as we predict, stellar population studies that rely on sampling a limited fraction of a galaxy can give a biased view of its global star formation history. We show that central fields can be biased young by a few Gyrs while outer fields are biased old. Fields positioned near the 2D half-light radius will provide the least biased measure of a dwarf galaxy's global star formation history.Comment: 13 pages, 8 figures. Submitted to MNRAS, comments welcom

A profile in FIRE: resolving the radial distributions of satellite galaxies in the Local Group with simulations

While many tensions between Local Group (LG) satellite galaxies and LCDM cosmology have been alleviated through recent cosmological simulations, the spatial distribution of satellites remains an important test of physical models and physical versus numerical disruption in simulations. Using the FIRE-2 cosmological zoom-in baryonic simulations, we examine the radial distributions of satellites with Mstar > 10^5 Msun around 8 isolated Milky Way- (MW) mass host galaxies and 4 hosts in LG-like pairs. We demonstrate that these simulations resolve the survival and physical destruction of satellites with Mstar >~ 10^5 Msun. The simulations broadly agree with LG observations, spanning the radial profiles around the MW and M31. This agreement does not depend strongly on satellite mass, even at distances <~ 100 kpc. Host-to-host variation dominates the scatter in satellite counts within 300 kpc of the hosts, while time variation dominates scatter within 50 kpc. More massive host galaxies within our sample have fewer satellites at small distances, likely because of enhanced tidal destruction of satellites via the baryonic disks of host galaxies. Furthermore, we quantify and provide fits to the tidal depletion of subhalos in baryonic relative to dark matter-only simulations as a function of distance. Our simulated profiles imply observational incompleteness in the LG even at Mstar >~ 10^5 Msun: we predict 2-10 such satellites to be discovered around the MW and possibly 6-9 around M31. To provide cosmological context, we compare our results with the radial profiles of satellites around MW analogs in the SAGA survey, finding that our simulations are broadly consistent with most SAGA systems.Comment: 18 pages, 10 figures, plus appendices. Main results in figures 2, 3, and 4. Accepted versio

Communication and signal exchange in the Rhizobium bradyrhizobium legume system

A new comprehensive communication concept in the Rhizobium/Bradyrhizobium legume symbiosis was developed. It includes a root zone specific flavonoid exudation, the differential activity of phenylpropane/acetate pathway derivatives on chemotaxis, nod-gene inducing activity and phytoalexin resistance induction on the microsymbiont side (Bradyrhizobium). Nod factor production from the microsymbiont affects the host plant in root hair curling and meristem induction. Phytoalexin production in the host plant is also an early response, however repressed to a low level after a few hours. Another strategy of the microsymbiont to overcome phytoalexin effects is degradation of phytoalexins in Rhizobium leguminosarum bv. vicieae. Competitiveness within the same infection group of the microsymbiont was studied with gus-gene fusion, using the blue coloured nodules to easily discriminate marked strains from unmarked competitors. New exopolysaccharide (EPS) mutants of Bradyrhizobium japonicum were reconstructed homologous with a DNA region to exoB gene of Rhizobium meliloti. Their clearly reduced competitiveness of nodulation, demonstrates that exopolysaccharides of Bradyrhizohium japonicum also have an important function during the early stages of this symbiotic interaction