Frontier Fields: High-Redshift Predictions and Early Results

The Frontier Fields program is obtaining deep Hubble and Spitzer Space Telescope images of new "blank" fields and nearby fields gravitationally lensed by massive galaxy clusters. The Hubble images of the lensed fields are revealing nJy sources (AB mag > 31), the faintest galaxies yet observed. In this paper, we present high-redshift (z > 6) number count predictions for the full program and candidates in three of the first Hubble Frontier Fields images. The full program will transform our understanding of galaxy evolution in the first 600 million years (z > 9). Where previous programs yielded perhaps a dozen z > 9 candidates, the Frontier Fields may yield ~70 (~6 per field). We base this estimate on an extrapolation of luminosity functions observed between 4 < z < 8 and gravitational lensing models submitted by the community. However, in the first two deep infrared Hubble images obtained to date, we find z ~ 8 candidates but no strong candidates at z > 9. This might suggest a deficit of faint z > 9 galaxies as also reported in the Ultra Deep Field (even while excesses of brighter z > 9 galaxies were reported in shallower fields). At these redshifts, cosmic variance (field-to-field variation) is expected to be significant (greater than +/-50%) and include clustering of early galaxies formed in overdensities. The full Frontier Fields program will significantly mitigate this uncertainty by observing six independent sightlines each with a lensing cluster and nearby blank field.Comment: Submitted for publication in the Astrophysical Journal. 15 pages, 17 figure

Possible petrogenetic associations among igneous components in North Massif soils: Evidence in 2-4 mm soil particles from 76503

Studies of Apollo 17 highland igneous rocks and clasts in breccias from the North and South Massifs have described magnesian troctolite, norite, anorthositic gabbro, dunite, spinel cataclasites, and granulitic lithologies that may have noritic anothosite or anorthositic norite/gabbro as igneous precursors, and have speculated on possible petrogenetic relationships among these rock types. Mineral compositions and relative proportions of plagioclase and plagioclase-olivine particles in samples 76503 indicate that the precursor lithology of those particles were troctolitic anorthosite, not troctolite. Mineral and chemical compositions of more pyroxene-rich, magnesian breccias and granulites in 76503 indicate that their precursor lithology was anorthositic norite/gabbro. The combination of mineral compositions and whole-rock trace-element compositional trends supports a genetic relationship among these two groups as would result from differentiation of a single pluton. Although highland igneous lithologies in Apollo 17 materials have been described previously, the proportions of different igneous lithologies present in the massifs, their frequency of association, and how they are related are not well known. We consider the proportions of, and associations among, the igneous lithologies found in a North Massif soil, which may represent those of the North Massif or a major part of it

Aim High or Go Low? Pricing Strategies and Enrollment Effects when the Net Price Elasticity Varies with Need and Ability

Detailed data on individual applicants to a large public university are used to demonstrate that net price responsiveness decreases with need and ability. Enrollment effects are simulated and show a movement towards a high tuition/high aid (low tuition/low aid) policy significantly lowers (raises) tuition revenue with a modest increase (decrease) in the number of aid-eligible students

Updating the Farm Bill Safety Net in an Expanding Sea of Risk

Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety, H10,

North Massif lithologies and chemical compositions viewed from 2-4 mm particles of soil sample 76503

We identify the lithologic and compositional components of soil 76503 based on INAA of 243 2-4-mm particles and 72 thin sections from these and associated 1-2-mm particles (76502). We present a statistical distribution of the major compositional types as the first step of a detailed comparative study of the North and South Massifs. The soil sample was collected well away from any boulder and is more representative of typical North Massif material than any single large rock or boulder sample. So far, our examination of the 76503 particles has provided a better definition of precursor igneous lithologies and their petrogenetic relationships. It has enabled us to refine the nature of mixing components for the North Massif less than 1-mm fines. It has confirmed the differences in lithologies and their proportions between materials of the North and South Massifs; e.g., the North Massif is distinguished by the absence of a 72275-type KREEP component, the abundance of a highly magnesian igneous component, and the absence of certain types of melt compositions found in the South Massif samples

Results of a partial cycloplegic on the visual system

Results of a partial cycloplegic on the visual syste

Additive Manufactured Loop Heat Pipe with Deployable Radiator to Unlock CubeSat Thermal Capacity

As the cost for access to space continues to lower, there is a trend toward higher power compact payloads in CubeSats. This leads to thermal and power limitations to maintain payloads in appropriate operating temperatures. The problem is two-fold: 1) the high heat flux due to compact design and 2) the limited radiator area for heat rejection. The high heat flux ( \u3e 2-3W/cm2) demands a two-phase solution to remove heat effectively without large temperature gradients ( \u3c 5°C) and is ideally passive for reduced complexity and cost. CubeSats also inherently have a limited radiator area. To make the most of the area, radiators are designed to be isothermalized at the highest temperature to reject as much heat as possible. Higher operating temperatures allow more heat to be rejected through the limited radiator area but is restricted by payload operating temperatures; thus, a deployable radiator is desirable to increase radiator area and allow for greater heat rejection. Conduction-only solutions such as thermal straps have high thermal resistance and do not allow for iso thermalization of the radiator. Thus, a two-phase approach is desirable. The solution to this two-fold problem is the utilization of an additively manufactured Loop Heat Pipe (LHP) with a deployable radiator. Additive manufacturing enables order of magnitude lower cost and lead time than traditional designs and allows for advanced miniaturized complex geometries for mass and volume savings. It offers the ability to be built with the CubeSat bus as a single-part assembly, serving as an integral thermo-structural member of the spacecraft. Additionally, LHPs allow for two-phase heat transfer across deployment mechanisms, allowing for isothermalization of both integrated and deployable radiators, unlocking the CubeSat Thermal Capacity

Money for Nothing? The Impact of Changes in the Pell Grant Program on Institutional Revenues and the Placement of Needy Students

Using new institutional-level data, we assess the impact of changing federal aid levels on institutional-level Pell revenues. Using various policy instruments associated with Pell generosity, we quantify the sensitivity of institutional Pell revenues to the generosity of the Pell Grant program. In general, we find an elastic response of institutional Pell revenues with respect to the maximum Pell award, where other policy instruments associated with Pell generosity are found to have an inelastic or zero impact. We also document significant asymmetries across institutional selectivity, both in magnitude and in terms of which channel accounts for the measured sensitivity—award values directly or institutional enrollment. In the end, exogenous changes in the federal Pell Grant program are found to correlate strongly with changes in the distribution of needy students and revenues across institutional quality