Effective description of dark matter as a viscous fluid

Treating dark matter at large scales as an effectively viscous fluid provides an improved framework for the calculation of the density and velocity power spectra compared to the standard assumption of an ideal pressureless fluid. We discuss how this framework can be made concrete through an appropriate coarse-graining procedure. We also review results that demonstrate that it improves the convergence of cosmological perturbation theory.Comment: 8 pages, 3 figures, talk by N. Tetradis at Quarks-2016, includes unpublished materia

Spatial displays as a means to increase pilot situational awareness

Experiences raise a number of concerns for future spatial-display developers. While the promise of spatial displays is great, the cost of their development will be correspondingly large. The knowledge and skills which must be coordinated to ensure successful results is unprecedent. From the viewpoint of the designer, basic knowledge of how human beings perceive and process complex displays appears fragmented and largely unquantified. Methodologies for display development require prototyping and testing with subject pilots for even small changes. Useful characterizations of the range of differences between individual users is nonexistent or at best poorly understood. The nature, significance, and frequency of interpretation errors associated with complex integrated displays is unexplored and undocumented territory. Graphic displays have intuitive appeal and can achieve face validity much more readily than earlier symbolic displays. The risk of misleading the pilot is correspondingly greater. Thus while some in the research community are developing the tools and techniques necessary for effective spatial-display development, potential users must be educated about the issues so that informed choices can be made. The scope of the task facing all is great. The task is challenging and the potential for meaningful contributions at all levels is high indeed

An Inconsistency in the Simulation of Bose-Einstein Correlations

We show that the formalism commonly used to implement Bose-Einstein correlations in Monte-Carlo simulations can lead to values of the two-particle correlator significantly smaller than unity, in the case of sources with strong position-momentum correlations. This is more pronounced when the phase space of the emitted particles is strongly reduced by experimental acceptance or kinematic analysis selections. It is inconsistent with general principles according to which the Bose-Einstein correlator is larger than unity. This inconsistency seems to be rooted in the fact that quantum mechanical localization properties are not taken into account properly.Comment: 10 pages, LaTe

Non-Abelian Energy Loss at Finite Opacity

A systematic expansion in opacity, $L/\lambda$, is used to clarify the non-linear behavior of induced gluon radiation in quark-gluon plasmas. The inclusive differential gluon distribution is calculated up to second order in opacity and compared to the zeroth order (factorization) limit. The opacity expansion makes it possible to take finite kinematic constraints into account that suppress jet quenching in nuclear collisions below RHIC ($\sqrt{s}=200$ AGeV) energies.Comment: 4 pages (revtex) with 3 eps figures, submitted to PR

Ethical Leadership: Life Story of George Ciampa, U.S. WWII Military Veteran and Community Leader

This qualitative research study explored the influence of life experiences and personal ethics of George Ciampa, a United States military veteran; his work in establishing American military cemeteries in Europe; and later work as a community leader committed to teaching American youth about the cost of freedom. Dimensions of ethical leadership and public service motivation served as the theoretical framework for the study. The research extended knowledge on ethical constructs within the fields of leadership studies and public administration; recorded personal experiences that were absent in military historical archives; and increased awareness of aspects of the U.S. military subculture. The research exploration was guided by an overarching question of how Ciampa reflected on his sense of public service over his lifetime. The study employed narrative life story methodology and visual research methods. Data collection was an iterative process and included segmented life story interviews and historical archival research. Findings included identification of a major theme (liberty) and three supporting sub-themes (duty, honor, and country) influencing Ciampa’s life and leadership path. A comparative analysis of the themes discovered with shared tenets of ethical leadership and public service motivation is provided. This dissertation is available in open access at AURA: Antioch University Repository and Archive, http://aura.antioch.edu/, and OhioLINK ETD Center, https://etd.ohiolink.edu/

Virtual Reality 3rd person camera behavior modes

We describe and evaluate five different level design independent modes of handling camera behavior in the 3rd person game LizzE – And the Light of Dreams in Virtual Reality. The behavior of the different modes will each be illustrated in detail. To evaluate the modes A: Fast circling, B: Lazy Circling, C: No Circling, D: Blink circling and E: Buffered pulling, an experimental study with 33 subjects was conducted. An analysis of the resulting data will show why Buffered pulling seems to be the most promising of the examined modes. We elaborate on the quantitative and qualitative hybrid experiment design and methodology. Eventually the advantages and disadvantages of the five tested modes are discussed in terms of supporting the gameplay, player enjoyment, in game performance and the tendency to induce nausea

An experiment design: investigating VR locomotion & virtual object interaction mechanics

In this paper, we describe an experiment outline on investigating design and user experience related aspects of several virtual reality locomotion and virtual object interaction mechanics. These mechanics will be based on consumer hardware like a common game controllers, an infrared hand and finger tracking device, VR hand controllers and an omnidirectional treadmill. Corresponding related work will contextualize and motivate this research. The projected experimental study will be based on user test sessions with a specifically developed 1st person VR puzzle horror game, called Gooze. A hybrid approach of self-assessment, in-game parameter tracking and session observations will be proposed for the investigation. Statistical analysis methods will be suggested to evaluate results. Furthermore, this paper will give an overview of the game and elaborate on design, gameplay and user experience related insights of already conducted informal pre-studies with it

How sensitive are high-pt electron spectra at RHIC to heavy quark energy loss?

In nucleus-nucleus collisions, high-pt electron spectra depend on the medium modified fragmentation of their massive quark parents, thus giving novel access to the predicted mass hierarchy of parton energy loss. Here we calculate these spectra in a model, which supplements the perturbative QCD factorization formalism with parton energy loss. In general, we find - within large errors - rough agreement between theory and data on the single inclusive electron spectrum in pp, its nuclear modification factor, and its azimuthal anisotropy. However, the nuclear modification factor depends on the relative contribution of charm and bottom production, which we find to be affected by large perturbative uncertainties. In order for electron measurements to provide a significantly more stringent test of the expected mass hierarchy, one must then disentangle the b- and c-decay contributions, for instance by reconstructing the displaced decay vertices.Comment: 9 pages RevTex, 4 eps-figures, asci-file containing numerical tables of results include

Local multiplayer immersion affected by 3D stereoscopy

In this paper, we describe an experimental study, which evaluates how 3D stereoscopy affects player immersion in a possibly very distracting local multiplayer game. The game “Nicely Dicely” was specifically developed for this purpose, with 3D stereoscopy in mind, right from the beginning. Groups of participants were competitively playing the game in non-3D monoscopic and 3D stereoscopic presentations via a 3D compatible projector and corresponding active shutter glasses. In the following, we elaborate on the game and our quantitative and qualitative hybrid experiment design and methodology. An analysis of the resulting data will show that, indeed 3D stereoscopy significantly increases spatial presence, involvement and player immersion, even in a local multiplayer situation. Furthermore, some guiding insights relating the game’s design will be illustrated

Calculating the Jet Quenching Parameter from AdS/CFT

Models of medium-induced radiative parton energy loss account for the strong suppression of high-pT hadron spectra in $\sqrt{s_{NN}}=200$ GeV Au-Au collisions at RHIC in terms of a single "jet quenching parameter'' $\hat q$. The available suite of jet quenching measurements make $\hat q$ one of the experimentally best constrained properties of the hot fluid produced in RHIC collisions. We observe that $\hat q$ can be given a model-independent, nonperturbative, quantum field theoretic definition in terms of the short-distance behavior of a particular light-like Wilson loop. We then use the AdS/CFT correspondence to obtain a strong-coupling calculation of $\hat q$ in hot N=4 supersymmetric QCD, finding $\hat{q}_{SYM} = 26.69 \sqrt{\alpha_{SYM} N_c} T^3$ in the limit in which both $N_c$ and $4\pi\alpha_{SYM} N_c$ are large. We thus learn that at strong coupling $\hat q$ is not proportional to the entropy density $s$, or to some "number density of scatterers'' since, unlike the number of degrees of freedom, $\hat q$ does not grow like $N_c^2$.Comment: Version accepted for publication in Phys. Rev. Lett.; factor of Sqrt[2] error corrected, improving agreement between $\hat q$ in N=4 SYM and that extracted from RHIC dat