5,927 research outputs found

    “Most Damning of All
 I Think I Can Live with It”: Captain Sisko, President Obama, and Emotional Geopolitics

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    This paper argues that the proliferation of geographical inquiry into popular culture as a prism for understanding geopolitical processes can benefit from more sustained engagement with psychoanalytic theory, particularly the work of Melanie Klein . Klein’s account of guilt and the urge to make reparation as both central to the development of conscience and profoundly unevenly distributed contributes to a critique of dominant, uneven geographies of guilt and encourages a nuanced approach to guilt’s potential ethical implications . To illustrate, I identify resonances between the contradictory legacy of the Obama administration and the character of Captain Sisko on the television program Star Trek: Deep Space Nine . Both Obama and Sisko, in some ways uniquely empathetic to the uneven distribution of suffering, also authorize forms of violence that differentiate among the relative values of civilian lives . Yet Sisko’s and Obama’s “bloody messes,” I insist, prove not simply individual failings, but matters of unevenl

    Constitutional Law - Jury Selection - Peremptory Challenges

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    The United States Supreme Court held that intentional gender discrimination by state actors when exercising peremptory challenges in the jury selection process violates the Equal Protection Clause of the Fourteenth Amendment. J.E.B. v. Alabama ex rel. T.B., 114 S. Ct. 1419 (1994)

    Efficient numerical approaches for predicting supersonic flows with viscous-inviscid interaction

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    Three different approaches for efficiently computing supersonic flow fields with strong viscous/inviscid interaction are critically examined. First, the single-pass philosophy employed for the solution of the parabolized Navier-Stokes (PNS) equations is considered. Through study of a model problem, the divergent space-marching solution that occurs when the streamwise pressure gradient is approximated using a backward difference is shown to be the response of the numerical algorithm to an ill-posed problem. In addition, it is shown that the so-called minimum marching step size is related to the longest wavelength that the finite-difference mesh is capable of resolving, not the thickness of the subsonic layer. Based on comparisons with other computed results, the single-pass philosophy is inadequate purely from the standpoint that it suppresses the streamwise elliptic behavior present in the solution;A second-order global pressure iteration (GPI) algorithm is developed using the Vigneron splitting to determine the portion of the streamwise pressure gradient that is responsible for streamwise elliptic behavior. A second-order finite-difference scheme is developed from a heuristic stability analysis of a model problem. A GPI algorithm is discussed in terms of upwind relaxation schemes that appear in the literature. For flows with streamwise separation, the FLARE approximation is employed to stabilize the iteration. Results predicted using the GPI algorithm show good agreement with results presented in the literature;In addition to the GPI algorithm, a new second-order algorithm is developed using a hybrid approach. The standard conservative PNS algorithm is employed in the outer supersonic flow, while in the subsonic region near the wall a split coefficient matrix (SCM) scheme is used to determine the direction of differencing for the streamwise convective flux vector. The second-order streamwise differencing scheme developed for the GPI algorithm is used in the SCM scheme while central differencing is employed for the transverse derivatives. Results predicted using the hybrid algorithm are very similar to results predicted using the GPI scheme except in the regions of reversed flow. The hybrid algorithm is less efficient than the GPI algorithm but more robust

    Measuring dark matter ellipticity of Abell 901/902 using Particle Based Lensing

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    We present a non-parametric measure of the ellipticity and the alignment of the dark matter halos in Abell 901/902 supercluster. This super-cluster is a system of four separate peaks in a 0.5∘×0.5∘0.5^{\circ}\times0.5^{\circ} field of view. We map the mass distribution of each individual peak using an improved version of Particle Based Lensing (PBL) and measure the ellipticity of the dark matter halos associated with two of the peaks directly from the mass map and by fitting them to a singular isothermal ellipse. The parametric and non-parametric measurements are consistent for A901b while the position angle for the Southwest Group is different for the two techniques. We account for this discrepancy to substructure present in the Southwest Peak. We estimate an axis ratio of 0.37±0.10.37\pm 0.1 for A901b and 0.54−0.09+0.080.54^{+0.08}_{-0.09} for the Southwest Group.Comment: submitted to APJ, 25 pages, 13 figure

    A Comparison of Simple Mass Estimators for Galaxy Clusters

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    High-resolution N-body simulations are used to investigate systematic trends in the mass profiles and total masses of clusters as derived from 3 simple estimators: (1) the weak gravitational lensing shear field under the assumption of an isothermal cluster potential, (2) the dynamical mass obtained from the measured velocity dispersion under the assumption of an isothermal cluster potential, and (3) the classical virial estimator. The clusters consist of order 2.5e+05 particles of mass m_p \simeq 10^{10} \Msun, have triaxial mass distributions, and significant substructure exists within their virial radii. Not surprisingly, the level of agreement between the mass profiles obtained from the various estimators and the actual mass profiles is found to be scale-dependent. The virial estimator yields a good measurement of the total cluster mass, though it is systematically underestimated by of order 10%. This result suggests that, at least in the limit of ideal data, the virial estimator is quite robust to deviations from pure spherical symmetry and the presence of substructure. The dynamical mass estimate based upon a measurement of the cluster velocity dispersion and an assumption of an isothermal potential yields a poor measurement of the total mass. The weak lensing estimate yields a very good measurement of the total mass, provided the mean shear used to determine the equivalent cluster velocity dispersion is computed from an average of the lensing signal over the entire cluster (i.e. the mean shear is computed interior to the virial radius). [abridged]Comment: Accepted for publication in The Astrophysical Journal. Complete paper, including 3 large colour figures can also be obtained from http://bu-ast.bu.edu/~brainerd/preprints

    MC2^2: Subaru and Hubble Space Telescope Weak-Lensing Analysis of the Double Radio Relic Galaxy Cluster PLCK G287.0+32.9

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    The second most significant detection of the Planck Sunyaev Zel'dovich survey, PLCK~G287.0+32.9 (z=0.385z=0.385) boasts two similarly bright radio relics and a radio halo. One radio relic is located ∌400\sim 400 kpc northwest of the X-ray peak and the other ∌2.8\sim 2.8 Mpc to the southeast. This large difference suggests that a complex merging scenario is required. A key missing puzzle for the merging scenario reconstruction is the underlying dark matter distribution in high resolution. We present a joint Subaru Telescope and {\it Hubble Space Telescope} weak-lensing analysis of the cluster. Our analysis shows that the mass distribution features four significant substructures. Of the substructures, a primary cluster of mass $M_{200\text{c}}=1.59^{+0.25}_{-0.22}\times 10^{15} \ h^{-1}_{70} \ \text{M}_{\odot}dominatestheweak−lensingsignal.Thisclusterislikelytobeundergoingamergerwithone(ormore)subclusterwhosemassisapproximatelyafactorof10lower.Onecandidateisthesubclusterofmass dominates the weak-lensing signal. This cluster is likely to be undergoing a merger with one (or more) subcluster whose mass is approximately a factor of 10 lower. One candidate is the subcluster of mass M_{200\text{c}}=1.16^{+0.15}_{-0.13}\times 10^{14} \ h^{-1}_{70} \ \text{M}_{\odot}located located \sim 400kpctothesoutheast.ThelocationofthissubclustersuggeststhatitsinteractionwiththeprimaryclustercouldbethesourceoftheNWradiorelic.Anothersubclusterisdetected kpc to the southeast. The location of this subcluster suggests that its interaction with the primary cluster could be the source of the NW radio relic. Another subcluster is detected \sim 2MpctotheSEoftheX−raypeakwithmass Mpc to the SE of the X-ray peak with mass M_{200\text{c}}=1.68^{+0.22}_{-0.20}\times 10^{14} \ h^{-1}_{70} \ \text{M}_{\odot}.ThisSEsubclusterisinthevicinityoftheSEradiorelicandmayhavecreatedtheSEradiorelicduringapastmergerwiththeprimarycluster.Thefourthsubcluster,. This SE subcluster is in the vicinity of the SE radio relic and may have created the SE radio relic during a past merger with the primary cluster. The fourth subcluster, M_{200\text{c}}=1.87^{+0.24}_{-0.22}\times 10^{14} \ h^{-1}_{70} \ \text{M}_{\odot}$, is northwest of the X-ray peak and beyond the NW radio relic.Comment: 19 pages, 14 figures; Accepted to Ap

    Grave Negotiations: The Rhetorical Foundations of American World War I Cemeteries in Europe

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    This dissertation uncovers the processes of negotiation between private citizens, President Woodrow Wilson's administration, the War Department, and the Commission of Fine Arts that led to the establishment and final visual presentation of the United States permanent World War I cemeteries in Europe (sites that are still frequented by tens of thousands of international visitors each year). It employs archival research and the analysis of newspapers and photographs to recover the voices of the many stakeholders involved in the cemeteries' foundation. Whereas previous studies have attempted to understand American World War I commemoration practices by focusing on postwar rituals of remembrance alone, my study contextualizes and explains postwar commemoration by analyzing the political ideologies, public rhetoric, and material realities of the war years (1914-1918)—ideologies, rhetoric, and material realities that shaped official and vernacular projects of memory after the Armistice. Providing what I believe is the first complete history of American World War I cemeteries in Europe, my dissertation situates these rhetorically charged sites within contemporary political debates about what it meant for U.S. soldiers to die on foreign soil; what would constitute the "proper" treatment and commemoration of the nation's war dead; how much control the U.S. government should have over the lives and bodies of American citizens; and, how best to communicate the nation's image to international populations
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