Non-local dispersal

We consider a model of spatial spread that has applications in both material science and biology. The classical models are based upon partial differential equations, in particular reaction-diffusion equations. Here the dispersal term is given in terms of an integral operator and we restrict ourselves to the scalar case

Quantum entanglement and fixed-point bifurcations

How does the classical phase space structure for a composite system relate to the entanglement characteristics of the corresponding quantum system? We demonstrate how the entanglement in nonlinear bipartite systems can be associated with a fixed point bifurcation in the classical dynamics. Using the example of coupled giant spins we show that when a fixed point undergoes a supercritical pitchfork bifurcation, the corresponding quantum state - the ground state - achieves its maximum amount of entanglement near the critical point. We conjecture that this will be a generic feature of systems whose classical limit exhibits such a bifurcation.Comment: v2: Structure of the paper changed for clarity, reduced length, now 9 pages with 6 figure

A Large Mass of H_2 in the Brightest Cluster Galaxy in Zwicky 3146

We present the Spitzer/IRS mid-infrared spectrum of the infrared-luminous (L_(IR) = 4 × 10^(11) L_☉) brightest cluster galaxy (BCG) in the X-ray-luminous cluster Zwicky 3146 (Z3146; z = 0.29). The spectrum shows strong aromatic emission features, indicating that the dominant source of the infrared luminosity is star formation. The most striking feature of the spectrum, however, is the exceptionally strong molecular hydrogen (H_2) emission lines, which seem to be shock-excited. The line luminosities and inferred warm H_2 gas mass (~10^(10) M_☉) are 6 times larger than those of NGC 6240, the most H_2-luminous galaxy at z ≲ 0.05. Together with the large amount of cold H_2 detected previously (~10^(11) M_☉), this indicates that the Z3146 BCG contains disproportionately large amounts of both warm and cold H_2 gas for its infrared luminosity, which may be related to the intracluster gas cooling process in the cluster core

Connecting Individuals with Social Services: The Academic Library\u27s Role

As socioeconomically-disadvantaged people become a core user base for libraries, some libraries have collaborated with non-library workers to connect their user communities with beneficial social services, which ties in with librarianship’s values of promoting social justice and providing for the common good. As public libraries earn attention and kudos for connecting their communities to social services, the question arises as to the role of the academic library in connecting our campus community with resources on services for societal needs. Working with existing campus and community organizations can create many positive networks for our library users, our institutions and our larger communities. Focusing on socioeconomic issues, this article will discuss the history of the trend to connect libraries and their user communities with social service providers and analysis from the perspective of librarianship and social service professionals. It will then will present a rationale for working within our academic communities in this way, and explore existing programs connecting academic library users with social services as well as present some low-barrier entry points for interested libraries. The potential exists for academic libraries to build strong collaborations that will boost retention and completion for students, as well as promote social justice and the common good. This article is based on presentations and papers delivered at IFLA RISS 2015, CAPAL 2016 and ALA 2016, some versions of which were previously published online

Reducing Cascading Failure Risk by Increasing Infrastructure Network Interdependency

Increased coupling between critical infrastructure networks, such as power and communication systems, will have important implications for the reliability and security of these systems. To understand the effects of power-communication coupling, several have studied interdependent network models and reported that increased coupling can increase system vulnerability. However, these results come from models that have substantially different mechanisms of cascading, relative to those found in actual power and communication networks. This paper reports on two sets of experiments that compare the network vulnerability implications resulting from simple topological models and models that more accurately capture the dynamics of cascading in power systems. First, we compare a simple model of topological contagion to a model of cascading in power systems and find that the power grid shows a much higher level of vulnerability, relative to the contagion model. Second, we compare a model of topological cascades in coupled networks to three different physics-based models of power grids coupled to communication networks. Again, the more accurate models suggest very different conclusions. In all but the most extreme case, the physics-based power grid models indicate that increased power-communication coupling decreases vulnerability. This is opposite from what one would conclude from the coupled topological model, in which zero coupling is optimal. Finally, an extreme case in which communication failures immediately cause grid failures, suggests that if systems are poorly designed, increased coupling can be harmful. Together these results suggest design strategies for reducing the risk of cascades in interdependent infrastructure systems

The Panther strikes, a history of the U.S.S. San Juan CL54

The story of the United States cruiser San Juan is, in reality, the chronicle of a relatively small group of men, and of ships, bound together in allegiance to a common flag -- the colors of a free nation whose peacetime borders boast no fortifications, save the guns of a salt water fleet. It is the story of a Navy which arose from staggering defeat to bring the fleets of two aggressor nations to their knees, receiving their surrender within four months of each other. It is the saga of a sleek anti-aircraft cruiser whose graceful lines and latent power won for it the affectionate nickname Panther -- a nickname which matured, as the San Juan itself matured, through fifteen major engagements against an enemy victorious in every war since 1596. The sobriquet gained material being by way of a signalman\u27s sewing cunning and under Captain J. E. Maher, U.S.N., the San Juan\u27s first commanding officer, the Panther Flag gained recognition as a battle flag and from that time on flew from the foretruck during the Panther\u27s strikes against Japan. E.G. Hines, USNRhttps://digicom.bpl.lib.me.us/ww_reg_his/1152/thumbnail.jp

High Accuracy Near-infrared Imaging Polarimetry with NICMOS

The findings of a nine orbit calibration plan carried out during HST Cycle 15, to fully determine the NICMOS camera 2 (2.0 micron) polarization calibration to high accuracy, are reported. Recently Ueta et al. and Batcheldor et al. have suggested that NICMOS possesses a residual instrumental polarization at a level of 1.2-1.5%. This would completely inhibit the data reduction in a number of GO programs, and hamper the ability of the instrument to perform high accuracy polarimetry. We obtained polarimetric calibration observations of three polarimetric standards at three spacecraft roll angles separated by ~60deg. Combined with archival data, these observations were used to characterize the residual instrumental polarization in order for NICMOS to reach its full potential of accurate imaging polarimetry at p~1%. Using these data, we place an 0.6% upper limit on the instrumental polarization and calculate values of the parallel transmission coefficients that reproduce the ground-based results for the polarimetric standards. The uncertainties associated with the parallel transmission coefficients, a result of the photometric repeatability of the observations, are seen to dominate the accuracy of p and theta. However, the updated coefficients do allow imaging polarimetry of targets with p~1.0% at an accuracy of +/-0.6% and +/-15deg. This work enables a new caliber of science with HST.Comment: 13 pages, 9 figures, PASP accepte