Steady two dimensional free-surface flow over semi-infinite and finite-length corrugations in an open channel

Free-surface flow past a semi-infinite or a finite length corrugation in an otherwise flat and horizontal open channel is considered. Numerical solutions for the steady flow problem are computed using both a weakly nonlinear and fully nonlinear model. The new solutions are classified in terms of a depth-based Froude number and the four classical flow types (supercritical, subcritical, generalised hydraulic rise and hydraulic rise) for flow over a small bump. While there is no hydraulic fall solution for semi-infinite topography, we provide strong numerical evidence that such a solution does exist in the case of a finite length corrugation. Numerical solutions are also found for the other flow types for either semi-infinite or finite length corrugation. For subcritical flow over a semi-infinite corrugation, the free-surface profile is found to be quasiperiodic in nature. A discussion of the new results is made with reference to the classical problem of flow over a bump

Initialization and Readout of Spin Chains for Quantum Information Transport

Linear chains of spins acting as quantum wires are a promising approach to achieve scalable quantum information processors. Nuclear spins in apatite crystals provide an ideal test-bed for the experimental study of quantum information transport, as they closely emulate a one-dimensional spin chain. Nuclear Magnetic Resonance techniques can be used to drive the spin chain dynamics and probe the accompanying transport mechanisms. Here we demonstrate initialization and readout capabilities in these spin chains, even in the absence of single-spin addressability. These control schemes enable preparing desired states for quantum information transport and probing their evolution under the transport Hamiltonian. We further optimize the control schemes by a detailed analysis of $^{19}$F NMR lineshape

Explicitly solvable cases of one-dimensional quantum chaos

We identify a set of quantum graphs with unique and precisely defined spectral properties called {\it regular quantum graphs}. Although chaotic in their classical limit with positive topological entropy, regular quantum graphs are explicitly solvable. The proof is constructive: we present exact periodic orbit expansions for individual energy levels, thus obtaining an analytical solution for the spectrum of regular quantum graphs that is complete, explicit and exact

SARS-CoV-2 testing in North Carolina: Racial, ethnic, and geographic disparities

SARS-CoV-2 testing data in North Carolina during the first three months of the state's COVID-19 pandemic were analyzed to determine if there were disparities among intersecting axes of identity including race, Latinx ethnicity, age, urban-rural residence, and residence in a medically underserved area. Demographic and residential data were used to reconstruct patterns of testing metrics (including tests per capita, positive tests per capita, and test positivity rate which is an indicator of sufficient testing) across race-ethnicity groups and urban-rural populations separately. Across the entire sample, 13.1% (38,750 of 295,642) of tests were positive. Within racial-ethnic groups, 11.5% of all tests were positive among non-Latinx (NL) Whites, 22.0% for NL Blacks, and 66.5% for people of Latinx ethnicity. The test positivity rate was higher among people living in rural areas across all racial-ethnic groups. These results suggest that in the first three months of the COVID-19 pandemic, access to COVID-19 testing in North Carolina was not evenly distributed across racial-ethnic groups, especially in Latinx, NL Black and other historically marginalized populations, and further disparities existed within these groups by gender, age, urban-rural status, and residence in a medically underserved area

D-Branes and Fluxes in Supersymmetric Quantum Mechanics

Type 0A string theory in the (2,4k) superconformal minimal model backgrounds, with background ZZ D-branes or R-R fluxes can be formulated non-perturbatively. The branes and fluxes have a description as threshold bound states in an associated one-dimensional quantum mechanics which has a supersymmetric structure, familiar from studies of the generalized KdV system. The relevant bound state wavefunctions in this problem have unusual asymptotics (they are not normalizable in general, and break supersymmetry) which are consistent with the underlying description in terms of open and closed string sectors. The overall organization of the physics is very pleasing: The physics of the closed strings in the background of branes or fluxes is captured by the generalized KdV system and non-perturbative string equations obtained by reduction of that system (the hierarchy of equations found by Dalley, Johnson, Morris and Watterstam). Meanwhile, the bound states wavefunctions, which describe the physics of the ZZ D-brane (or flux) background in interaction with probe FZZT D-branes, are captured by the generalized mKdV system, and non-perturbative string equations obtained by reduction of that system (the Painleve II hierachy found by Periwal and Shevitz in this context).Comment: 41 pages, LaTe

Deformations of Lifshitz holography

The simplest gravity duals for quantum critical theories with z=2 `Lifshitz' scale invariance admit a marginally relevant deformation. Generic black holes in the bulk describe the field theory with a dynamically generated momentum scale Lambda as well as finite temperature T. We describe the thermodynamics of these black holes in the quantum critical regime where T >> Lambda^2. The deformation changes the asymptotics of the spacetime mildly and leads to intricate UV sensitivities of the theory which we control perturbatively in Lambda^2/T.Comment: 1+27 pages, 12 figure

Deconstructing holographic liquids

We argue that there exist simple effective field theories describing the long-distance dynamics of holographic liquids. The degrees of freedom responsible for the transport of charge and energy-momentum are Goldstone modes. These modes are coupled to a strongly coupled infrared sector through emergent gauge and gravitational fields. The IR degrees of freedom are described holographically by the near-horizon part of the metric, while the Goldstone bosons are described by a field-theoretical Lagrangian. In the cases where the holographic dual involves a black hole, this picture allows for a direct connection between the holographic prescription where currents live on the boundary, and the membrane paradigm where currents live on the horizon. The zero-temperature sound mode in the D3-D7 system is also re-analyzed and re-interpreted within this formalism.Comment: 21 pages, 2 figure

Spectra of regular quantum graphs

We consider a class of simple quasi one-dimensional classically non-integrable systems which capture the essence of the periodic orbit structure of general hyperbolic nonintegrable dynamical systems. Their behavior is simple enough to allow a detailed investigation of both classical and quantum regimes. Despite their classical chaoticity, these systems exhibit a ``nonintegrable analog'' of the Einstein-Brillouin-Keller quantization formula which provides their spectra explicitly, state by state, by means of convergent periodic orbit expansions.Comment: 32 pages, 10 figure

Space Flight Qualification on a Multi-Fiber Ribbon Cable and Array Connector Assembly

NASA's Goddard Space Flight Center (GSFC) cooperatively with Sandia National Laboratories completed a series of tests on three separate configurations of multi-fiber ribbon cable and MTP connector assemblies. These tests simulate the aging process of components during launch and long-term space environmental exposure. The multi-fiber ribbon cable assembly was constructed of non-outgassing materials, with radiation-hardened, graded index 100/140-micron optical fiber. The results of this characterization presented here include vibration testing, thermal vacuum monitoring, and extended radiation exposure testing data

Docetaxel-Loaded PLGA Nanoparticles Improve Efficacy in Taxane-Resistant Triple-Negative Breast Cancer

Novel treatment strategies, including nanomedicine, are needed for improving management of triple-negative breast cancer. Patients with triple-negative breast cancer, when considered as a group, have a worse outcome after chemotherapy than patients with breast cancers of other subtypes, a finding that reflects the intrinsically adverse prognosis associated with the disease. The aim of this study was to improve the efficacy of docetaxel by incorporation into a novel nanoparticle platform for the treatment of taxane-resistant triple-negative breast cancer. Rod-shaped nanoparticles encapsulating docetaxel were fabricated using an imprint lithography based technique referred to as Particle Replication in Nonwetting Templates (PRINT). These rod-shaped PLGA-docetaxel nanoparticles were tested in the C3(1)-T-antigen (C3Tag) genetically engineered mouse model (GEMM) of breast cancer that represents the basal-like subtype of triple-negative breast cancer and is resistant to therapeutics from the taxane family. Thi..