Strengthening Africa’s Contributions to Child Development Research: Introduction

The articles in this Special Section are based on contributions to an SRCD-sponsored invitational conference held in Victoria, Canada, in February 2009. This introductory article establishes the rationale for focusing on Africa as part of an effort to advance a more inclusive science of child development, provides a brief overview of the thrust of the other articles in the section, describes 2 research capacity-building initiatives that emerged from the conference, and concludes with reflective perspectives on conceptual and methodological considerations for a future African child development field

Rheology and Contact Lifetime Distribution in Dense Granular Flows

We study the rheology and distribution of interparticle contact lifetimes for gravity-driven, dense granular flows of non-cohesive particles down an inclined plane using large-scale, three dimensional, granular dynamics simulations. Rather than observing a large number of long-lived contacts as might be expected for dense flows, brief binary collisions predominate. In the hard particle limit, the rheology conforms to Bagnold scaling, where the shear stress is quadratic in the strain rate. As the particles are made softer, however, we find significant deviations from Bagnold rheology; the material flows more like a viscous fluid. We attribute this change in the collective rheology of the material to subtle changes in the contact lifetime distribution involving the increasing lifetime and number of the long-lived contacts in the softer particle systems.Comment: 4 page

Protecting State Constitutional Rights from Unconstitutional Conditions

The unconstitutional conditions doctrine limits the ability of governments to force individuals to choose between retaining a right and enjoying a government benefit. The doctrine has primarily remained a creature of federal law, with neither courts nor commentators focusing on the potentially important role of state doctrines of unconstitutional conditions. This omission has become especially significant during the COVID-19 pandemic, as actions by state and local governments have presented unconstitutional conditions questions in a range of novel contexts. The overruling of Roe v. Wade and the resulting focus on state constitutional rights to abortion will offer additional new settings for state unconstitutional conditions analysis. As attention turns to distinctive state constitutional rights — in the context of COVID-19 disputes, abortion litigation, and more generally — state courts should develop their own state doctrines of unconstitutional conditions, rather than simply reverting to federal unconstitutional conditions analysis. Three reasons in particular drive this doctrinal claim. First, the unconstitutional conditions doctrine helps to define the scope and weight of a constitutional right. A state court that ignores the unconstitutional conditions doctrine when considering the constitutionality of a state statute or regulation risks undermining the very nature of the right. Second, uncritically adopting federal doctrine ignores the state’s distinctive legal framework, interests, and history, all of which might lead to a deviation from federal law. With respect to the topics on which unconstitutional conditions litigation typically focuses, such as licenses and permits, the federal-state disparities are especially stark. Third, robust legal development in our federal system depends in part upon the interplay of different institutional interpreters. When state courts and federal courts engage in independent interpretative activity, they create the possibility of dialogue and mutual learning. This interpretive interplay enhances federal doctrine, as well as doctrinal development in other states. Given the gaps and inconsistencies in the unconstitutional conditions doctrine, such interjurisdictional enlightenment is especially needed in this area. After explaining why states should develop their own doctrines of unconstitutional conditions, we suggest the relevant considerations that should guide states in formulating their doctrines

Plug flow and the breakdown of Bagnold scaling in cohesive granular flows

Cohesive granular media flowing down an inclined plane are studied by discrete element simulations. Previous work on cohesionless granular media demonstrated that within the steady flow regime where gravitational energy is balanced by dissipation arising from intergrain forces, the velocity profile in the flow direction scales with depth in a manner consistent with the predictions of Bagnold. Here we demonstrate that this Bagnold scaling does not hold for the analogous steady-flows in cohesive granular media. We develop a generalization of the Bagnold constitutive relation to account for our observation and speculate as to the underlying physical mechanisms responsible for the different constitutive laws for cohesive and noncohesive granular media.Comment: 8 pages, 10 figure

The Ursinus Weekly, October 31, 1960

Second Forum to feature speaker on Bill of Rights • Pre-medders hear Dean of Jefferson • Conference on careers to be held in Phila. • Mr. Jones attends colloquium on college admissions in N.Y. • Sixty-one girls get sorority bids • Debating Club to hold meet on Tues., Nov. 1 • National Teacher Exams to be given on Feb. 11 • Big Little Sister party to be held Tuesday, Nov. 1 in college woods • Young Democrats hear Kennedy in Norristown on Sat. • YM-YW to sponsor formal political debate on Nov. 2 • New Lantern staff policy includes planned criticism • Newman Club to discuss All Saint\u27s Day at meeting • Young Republicans poll campus to determine student political leanings • APO initiates 17 new pledges • Chemistry society tours research laboratory • Society Hill Playhouse launches inaugural season • Frosh elect officers; Dave Kohr is president • Senior class to receive annuals • Spanish Club hears Dave Williams on October 17 • Editorial: A proposal • Letters to the editor • Hurrah! Brave new world • Point of interest • Reflections • Customs program called beneficial • Bears lose two games in soccer • Ursinus trackman sets AAU record • Wagner defeats Bears; Allebach is standout • Lassies divide during past week • Intramural corner • 1,350 fellowships offered by N.C.S. • Presidential humor • Y hears speaker on social work • Phila. Museum of Art to open new wing • Russian film premieres at Franklin Institute • Phila. art directors to have exhibition • Romance language teachers to attend dinner at Temple • Captain Dinneen of U.S. Army to visit Ursinus • Business Administration Club to hear Mr. King speak Weds.https://digitalcommons.ursinus.edu/weekly/1325/thumbnail.jp

Simultaneous Exoplanet Characterization and deep wide-field imaging with a diffractive pupil telescope

High-precision astrometry can identify exoplanets and measure their orbits and masses, while coronagraphic imaging enables detailed characterization of their physical properties and atmospheric compositions through spectroscopy. In a previous paper, we showed that a diffractive pupil telescope (DPT) in space can enable sub-microarcsecond accuracy astrometric measurements from wide-field images by creating faint but sharp diffraction spikes around the bright target star. The DPT allows simultaneous astrometric measurement and coronagraphic imaging, and we discuss and quantify in this paper the scientific benefits of this combination for exoplanet science investigations: identification of exoplanets with increased sensitivity and robustness, and ability to measure planetary masses to high accuracy. We show how using both measurements to identify planets and measure their masses offers greater sensitivity and provides more reliable measurements than possible with separate missions, and therefore results in a large gain in mission efficiency. The combined measurements reliably identify potentially habitable planets in multiple systems with a few observations, while astrometry or imaging alone would require many measurements over a long time baseline. In addition, the combined measurement allows direct determination of stellar masses to percent-level accuracy, using planets as test particles. We also show that the DPT maintains the full sensitivity of the telescope for deep wide-field imaging, and is therefore compatible with simultaneous scientific observations unrelated to exoplanets. We conclude that astrometry, coronagraphy, and deep wide-field imaging can be performed simultaneously on a single telescope without significant negative impact on the performance of any of the three techniques.Comment: 15 pages, 6 figures. This second paper, following the paper describing the diffractive pupil telescope (DPT) astrometric technique, shows how simultaneous astrometry and coronagraphy observations, enabled by the DPT concept, constrain the orbital parameters and mass of exoplanet

Scattering and Iron Fluorescence Revealed During Absorption Dips in Circinus X-1

We show that dramatic spectral evolution associated with dips occurring near phase zero in RXTE observations of Cir X-1 is well-fit by variable and at times heavy absorption (N_H > 10^24 cm^-2) of a bright component, plus an underlying faint component which is not attenuated by the variable column and whose flux is ~10% of that of the unabsorbed bright component. A prominent Fe emission line at ~6.5 keV is evident during the dips. The absolute line flux outside the dips is similar to that during the dips, indicating that the line is associated with the faint component. These results are consistent with a model in which the bright component is radiation received directly from a compact source while the faint component may be attributed to scattered radiation. Our results are also generally consistent with those of Brandt et al., who found that a partial- covering model could explain ASCA spectra of a low-to-high transition in Cir X-1. The relative brightness of the two components in our model requires a column density of ~2*10^23 cm^-2 if the faint component is due to Thomson scattering in material that mostly surrounds the source. We find that illumination of such a scattering cloud by the observed direct component would produce an Fe K-alpha fluorescence flux that is in rough agreement with the flux of the observed emission line. We also conclude that if the scattering medium is not highly ionized, our line of sight to the compact source does not pass through it. Finally, we discuss simple pictures of the absorbers responsible for the dips themselves.Comment: Accepted for publication in The Astrophysical Journal (23 pages, including 11 figures