3,636 research outputs found
Hermes, a Concerto for Violoncello and Orchestra
This thesis consists of a large composition for violoncello and orchestra, together with an analytical paper in which I discuss my compositional techniques and some of their historical antecedents. The composition draws on the genres of imaginary musical theater, the symphonic poem, and the concerto. It was also inspired by the story of Hermes, the messenger god from Greek mythology. While the myth partially informs the compositional structure, the work is ultimately meant to showcase the versatility of the cello, the coloristic range of the orchestra (in some cases emulating the orchestral styles of previous composers), the balance of cello and orchestra together, and the eclectic invocation of many compositional techniques separately and simultaneously. These techniques encompass set theory (the use of unordered pitch collections), polytonality, and serialism. It is composed in a post-romantic style
Alternative command funding and functional organization at the Space and Naval Warfare Systems Command (SPAWAR)
This thesis examines funding sources for two Space and Naval Warfare Systems Command (SPAWAR) System Centers. SPAWAR System Centers Chesapeake and SPAWAR ITC, located in New Orleans, is the focus of this thesis. This thesis conducts a through review of the current funding structure at each SPAWAR System Center. Funding options available to SPAWAR System Centers are mission funding, which are monies appropriated by Congress, and reimbursable funding, which are monies recovered from customers for services rendered. Strengths and weakness of each funding method are analyzed for potential improvement. Each SPAWAR System Center's business base is also studied in regard to opportunities to grow the existing customer base and to identify potential threats to current market share. After careful examination of existing funding methods and in depth interviews with top financial officials at the different SPAWAR System Centers, change recommendations to existing funding requirements and organizational structure are presented.http://archive.org/details/alternativecomma109451098
Aerothermodynamic Characteristics of Boundary Layer Transition and Trip Effectiveness of the HIFiRE Flight 5 Vehicle
An experimental wind tunnel test was conducted in the NASA Langley Research Center s 20-Inch Mach 6 Tunnel in support of the Hypersonic International Flight Research Experimentation Program. The information in this report is focused on the Flight 5 configuration, one in a series of flight experiments. This report documents experimental measurements made over a range of Reynolds numbers and angles of attack on several scaled ceramic heat transfer models of the Flight 5 vehicle. The heat transfer rate was measured using global phosphor thermography and the resulting images and heat transfer rate distributions were used to infer the state of the boundary layer on the windside, leeside and side surfaces. Boundary layer trips were used to force the boundary layer turbulent, and a study was conducted to determine the effectiveness of the trips with various heights. The experimental data highlighted in this test report were used determine the allowable roughness height for both the windside and side surfaces of the vehicle as well as provide for future tunnel-to-tunnel comparisons
The origin of ultra diffuse galaxies: stellar feedback and quenching
We test if the cosmological zoom-in simulations of isolated galaxies from the
FIRE project reproduce the properties of ultra diffuse galaxies. We show that
stellar feedback-generated outflows that dynamically heat galactic stars,
together with a passively aging stellar population after imposed quenching
(from e.g. infall into a galaxy cluster), naturally reproduce the observed
population of red UDGs, without the need for high spin halos or dynamical
influence from their host cluster. We reproduce the range of surface
brightness, radius and absolute magnitude of the observed z=0 red UDGs by
quenching simulated galaxies at a range of different times. They represent a
mostly uniform population of dark matter-dominated galaxies with M_star ~1e8
Msun, low metallicity and a broad range of ages. The most massive simulated
UDGs require earliest quenching and are therefore the oldest. Our simulations
provide a good match to the central enclosed masses and the velocity
dispersions of the observed UDGs (20-50 km/s). The enclosed masses of the
simulated UDGs remain largely fixed across a broad range of quenching times
because the central regions of their dark matter halos complete their growth
early. A typical UDG forms in a dwarf halo mass range of Mh~4e10-1e11 Msun. The
most massive red UDG in our sample requires quenching at z~3 when its halo
reached Mh ~ 1e11 Msun. If it, instead, continues growing in the field, by z=0
its halo mass reaches > 5e11 Msun, comparable to the halo of an L* galaxy. If
our simulated dwarfs are not quenched, they evolve into bluer low-surface
brightness galaxies with mass-to-light ratios similar to observed field dwarfs.
While our simulation sample covers a limited range of formation histories and
halo masses, we predict that UDG is a common, and perhaps even dominant, galaxy
type around Ms~1e8 Msun, both in the field and in clusters.Comment: 20 pages, 13 figures; match the MNRAS accepted versio
Optical Flow on Evolving Surfaces with an Application to the Analysis of 4D Microscopy Data
We extend the concept of optical flow to a dynamic non-Euclidean setting.
Optical flow is traditionally computed from a sequence of flat images. It is
the purpose of this paper to introduce variational motion estimation for images
that are defined on an evolving surface. Volumetric microscopy images depicting
a live zebrafish embryo serve as both biological motivation and test data.Comment: The final publication is available at link.springer.co
Effects of Dietary Sodium Intake on Blood Flow Regulation During Exercise in Salt Resistant Individuals
PURPOSE: Dietary sodium intake guidelines is ≤2,300 mg/day, yet is exceeded by 90% of Americans. This study examined the impact of a high sodium diet on blood flow regulation during exercise. METHODS: Six males (25 ± 2 years) consumed dietary sodium intake guidelines for two weeks, with one week salt-capsule supplemented (HS: 6,900 mg/day of sodium) and the other week placebo-capsule supplemented (LS: 2,300 mg/day of sodium). At the end of each week, peripheral hemodynamic measurements [blood flow (BF), shear rate (SR), and flow mediated dilation (FMD)/SR)] of the brachial and superficial femoral artery were taken during handgrip (HG) and plantar flexion (PF) exercise, respectively. Each exercise workload was 3 minutes and progressed by 8 kilograms until exhaustion. RESULTS: There were no differences between LS and HS in blood pressure (82 ± 4 v 80 ± 5 mmHg; p = 0.3) or heart rate (56 ± 6 v 59 ± 10 bpm; p = 0.4). HG and PF exercise increased BF, SR, and FMD/SR across workload (p \u3c 0.03 for all), but no difference between diets (p \u3e 0.05 for all). CONCLUSION: Despite previous reports that HS impairs resting vascular function, this study revealed that peripheral vascular function and blood flow regulation during exercise is not impacted by a HS diet.https://scholarscompass.vcu.edu/gradposters/1082/thumbnail.jp
Quickest Paths in Simulations of Pedestrians
This contribution proposes a method to make agents in a microscopic
simulation of pedestrian traffic walk approximately along a path of estimated
minimal remaining travel time to their destination. Usually models of
pedestrian dynamics are (implicitly) built on the assumption that pedestrians
walk along the shortest path. Model elements formulated to make pedestrians
locally avoid collisions and intrusion into personal space do not produce
motion on quickest paths. Therefore a special model element is needed, if one
wants to model and simulate pedestrians for whom travel time matters most (e.g.
travelers in a station hall who are late for a train). Here such a model
element is proposed, discussed and used within the Social Force Model.Comment: revised version submitte
But What About... Cosmic Rays, Magnetic Fields, Conduction, & Viscosity in Galaxy Formation
We present a suite of high-resolution cosmological simulations, using the
FIRE-2 feedback physics together with explicit treatment of magnetic fields,
anisotropic conduction and viscosity, and cosmic rays (CRs) injected by
supernovae (including anisotropic diffusion, streaming, adiabatic, hadronic and
Coulomb losses). We survey systems from ultra-faint dwarf (, ) through Milky Way
masses, systematically vary CR parameters (e.g. the diffusion coefficient
and streaming velocity), and study an ensemble of galaxy properties
(masses, star formation histories, mass profiles, phase structure,
morphologies). We confirm previous conclusions that magnetic fields,
conduction, and viscosity on resolved (pc) scales have small
effects on bulk galaxy properties. CRs have relatively weak effects on all
galaxy properties studied in dwarfs (, ), or at high redshifts (), for
any physically-reasonable parameters. However at higher masses () and , CRs can suppress star
formation by factors , given relatively high effective diffusion
coefficients . At lower
, CRs take too long to escape dense star-forming gas and lose energy to
hadronic collisions, producing negligible effects on galaxies and violating
empirical constraints from -ray emission. But around , CRs escape the galaxy and build up a
CR-pressure-dominated halo which supports dense, cool ( K) gas
that would otherwise rain onto the galaxy. CR heating (from collisional and
streaming losses) is never dominant.Comment: 35 pages, 23 figures. Updated to match published (MNRAS) versio
Addressing Teacher Shortages in the COVID-19 Landscape: Viewing Teacher Candidates as Assets
COVID-19 continues to impose dire consequences on all sectors of our public education system. Many students, particularly those from vulnerable populations, are receiving reduced amounts of direct instruction and are experiencing significant losses in learning. At the same time, educator preparation programs (EPPs) are struggling to ensure that teacher candidates have ample opportunities to apply their newly acquired pedagogical skills in high quality clinical placements. In this article we describe and provide exemplars as to how teacher candidates can serve as assets to school districts as they complete their field placements. We also offer specific strategies and practices for EPPs and school districts to maximize the productive and efficient integration of teacher candidates in both virtual and in-person environments
- …