Complex permittivity measurements of lunar samples at microwave and millimeter wavelengths

The relative dielectric constant and loss tangent of lunar sample 14163,164 (fine dust) were determined as a function of density at 9.375, 24, 35, and 60 GHz. In addition, such measurements have also been performed on lunar sample 14310,74 (solid rock) at 9.375 GHz. The loss tangent was found to be frequency independent at these test frequencies and had a value of 0.015 for the lunar dust sample

The MMI cash-futures spread on October 19, 1987

Includes bibliographical references (p. 29)

The essence of quintessence and the cost of compression

Standard two-parameter compressions of the infinite dimensional dark energy model space show crippling limitations even with current SN-Ia data. Firstly they cannot cope with rapid evolution - the best-fit to the latest SN-Ia data shows late and very rapid evolution to w_0 = -2.85. However all of the standard parametrisations (incorrectly) claim that this best-fit is ruled out at more than 2-sigma, primarily because they track it well only at very low redshifts, z < 0.2. Further they incorrectly rule out the observationally acceptable region w 1. Secondly the parametrisations give wildly different estimates for the redshift of acceleration, which vary from z_{acc}=0.14 to z_{acc}=0.59. Although these failings are largely cured by including higher-order terms (3 or 4 parameters) this results in new degeneracies which open up large regions of previously ruled-out parameter space. Finally we test the parametrisations against a suite of theoretical quintessence models. The widely used linear expansion in z is generally the worst, with errors of up to 10% at z=1 and 20% at z > 2. All of this casts serious doubt on the usefulness of the standard two-parameter compressions in the coming era of high-precision dark energy cosmology and emphasises the need for decorrelated compressions with at least three parameters.Comment: 7 pages, 4 colour figures, EmulateApJ; v2: includes Bayesian evidence analysis and table that were only present in published version, because of increased interest in Bayesian model comparison (no new material beyond the one in the published ApJL of 2004

The Environmental Benefits of Trees on an Urban University Campus

The University of Pennsylvania is situated on a rapidly growing and highly urbanized campus that, as of the summer of 2015, contained over 6,000 trees. Trees play an important ecological role within the urban environment, as well as support improved public health and provide aesthetic benefits to cities (Nowak et al. 2008; McPherson et al., 2003). This capstone project used the United States Department of Agriculture Forest Service’s software, i-Tree Eco, to quantify the ecosystem benefits that the University of Pennsylvania urban forest conveys to its community. Field research teams collected data on location and tree canopy size for 4,086 trees on 160 acres in the core of the Philadelphia campus during the summer of 2015. Trees within the Core Campus were estimated to store a total of 1,576,717 lbs of carbon and prevented $51,871 in building heating/cooling energy costs. This project will give Penn Facilities and Real Estate Services decision makers a more complete assessment of the value of their urban trees. This work will inform future tree management practices and create a precedent for ongoing urban forestry research efforts at Penn

Evolution of Network Architecture in a Granular Material Under Compression

As a granular material is compressed, the particles and forces within the system arrange to form complex and heterogeneous collective structures. Force chains are a prime example of such structures, and are thought to constrain bulk properties such as mechanical stability and acoustic transmission. However, capturing and characterizing the evolving nature of the intrinsic inhomogeneity and mesoscale architecture of granular systems can be challenging. A growing body of work has shown that graph theoretic approaches may provide a useful foundation for tackling these problems. Here, we extend the current approaches by utilizing multilayer networks as a framework for directly quantifying the progression of mesoscale architecture in a compressed granular system. We examine a quasi-two-dimensional aggregate of photoelastic disks, subject to biaxial compressions through a series of small, quasistatic steps. Treating particles as network nodes and interparticle forces as network edges, we construct a multilayer network for the system by linking together the series of static force networks that exist at each strain step. We then extract the inherent mesoscale structure from the system by using a generalization of community detection methods to multilayer networks, and we define quantitative measures to characterize the changes in this structure throughout the compression process. We separately consider the network of normal and tangential forces, and find that they display a different progression throughout compression. To test the sensitivity of the network model to particle properties, we examine whether the method can distinguish a subsystem of low-friction particles within a bath of higher-friction particles. We find that this can be achieved by considering the network of tangential forces, and that the community structure is better able to separate the subsystem than a purely local measure of interparticle forces alone. The results discussed throughout this study suggest that these network science techniques may provide a direct way to compare and classify data from systems under different external conditions or with different physical makeup

Fourth Amendment Accommodations: (UN)Compelling Public Needs, Balancing Acts, and the Fiction of Consent

The problems of public housing-including crime, drugs, and gun violence- have received an enormous amount of national attention. Much attention has also focused on warrantless searches and consent searches as solutions to these problems. This Note addresses the constitutionality of these proposals and asserts that if the Supreme Court\u27s current Fourth Amendment jurisprudence is taken to its logical extremes, warrantless searches in public housing can be found constitutional. The author argues, however, that such an interpretation fails to strike the proper balance between public need and privacy in the public housing context. The Note concludes by proposing alternative consent-based regimes that would pass constitutional muster

Aurora Volume 21

College formerly located at Olivet, Illinois and known as Olivet University, 1912-1923; Olivet College, 1923-1939, Olivet Nazarene College, 1940-1986, Olivet Nazarene University, 1986-https://digitalcommons.olivet.edu/arch_yrbks/1087/thumbnail.jp

Aurora Volume 21

College formerly located at Olivet, Illinois and known as Olivet University, 1912-1923; Olivet College, 1923-1939, Olivet Nazarene College, 1940-1986, Olivet Nazarene University, 1986-https://digitalcommons.olivet.edu/arch_yrbks/1087/thumbnail.jp

Dangling Bonds in Hexagonal Boron Nitride as Single-Photon Emitters.

Hexagonal boron nitride has been found to host color centers that exhibit single-photon emission, but the microscopic origin of these emitters is unknown. We propose boron dangling bonds as the likely source of the observed single-photon emission around 2 eV. An optical transition where an electron is excited from a doubly occupied boron dangling bond to a localized B p_{z} state gives rise to a zero-phonon line of 2.06 eV and emission with a Huang-Rhys factor of 2.3. This transition is linearly polarized with the absorptive and emissive dipole aligned. Because of the energetic position of the states within the band gap, indirect excitation through the conduction band will occur for sufficiently large excitation energies, leading to the misalignment of the absorptive and emissive dipoles seen in experiment. Our calculations predict a singlet ground state and the existence of a metastable triplet state, in agreement with experiment