Wind-tunnel model of study of downwash from stacks at Maui Electric Company Power Plant, Kahului, Hawaii

CER72-73JEC-SKN28.Prepared under contract to Stearns-Roger Incorporated.Includes bibliographical (pages 16-17).March 1973.Tests were conducted in the meteorological wind-tunnel using 1:200 scale model to determine the distribution of gas concentration resulting from gaseous plumes released from four stacks associated with Maui Electric Company Power-Plant at Kahului Hawaii. The tests were conducted over a model power-plant including all significant structures in the vicinity. Data obtained included photographs and color motion pictures of smoke-plume trajectories and plots of contaminant concentration down wind of the power-plant at ground-level sampling positions. The effects of wind direction and stack height on ground-level concentrations are established. Evaluation of test results revealed that an increase of stack height from 30.48 m to 60.96 m will reduce the maximum groundlevel concentrations by a factor of three to five depending upon the wind direction. Location of stacks upwind of the power-plant structures was found to show distinct improvement of plume characteristics

Wind loads on a house roof

CER72-73KJD-JEC22.March 1973.Includes bibliographical references (pages 40-42).Prepared under National Bureau of Standards Contract No. NBS 273-70.Circulating copy deaccessioned 2020.The wind loads on the roof of a house were experimentally investigated by placing a 1:50 scale model house in a wind tunnel capable of generating thick, turbulent shear flows. The effects of roof geometry and wind direction were isolated by making the wind-tunnel flow representative of natural winds over very flat, open terrain. This flow simulation was accomplished by placing vortex generators at the entrance to the wind-tunnel test section. Mean pressures, root-mean-square values of the fluctuating pressures, and instantaneous peak pressures were measured at 11 preselected locations on the model's roof for 24 wind directions. A secondary purpose of the study was to determine the effects of an upwind fence on the roof pressures

Wind-tunnel research on the mechanics of plumes in the atmosphere surface layer

Includes bibliographical references.Project No. 5-3 2512.Prepared for Department of the Army, U.S. Army Armament Research and Development Command, Chemical Systems Laboratory, Aberdeen Proving Ground.CER83-84JEC-PKS-MP12.The diffusion of a neutrally buoyant gas emitted from point sources into neutral, stable and unstable boundary layers that simulated atmospheric conditions were studied in a meteorological wind tunnel for flow over two surface roughnesses. Measurements were made of the mean flow velocities and temperatures, turbulence intensities, velocity correlations and gas concentrations in the diffusing plume. Empirical models were developed for predicting diffusion under all three stabilities studied

Robust Upward Dispersion of the Neutron Spin Resonance in the Heavy Fermion Superconductor Ce1−x_{1-x}Ybx_{x}CoIn5_5

The neutron spin resonance is a collective magnetic excitation that appears in copper oxide, iron pnictide, and heavy fermion unconventional superconductors. Although the resonance is commonly associated with a spin-exciton due to the $d$($s^{\pm}$)-wave symmetry of the superconducting order parameter, it has also been proposed to be a magnon-like excitation appearing in the superconducting state. Here we use inelastic neutron scattering to demonstrate that the resonance in the heavy fermion superconductor Ce$_{1-x}$Yb$_{x}$CoIn$_5$ with $x=0,0.05,0.3$ has a ring-like upward dispersion that is robust against Yb-doping. By comparing our experimental data with random phase approximation calculation using the electronic structure and the momentum dependence of the $d_{x^2-y^2}$-wave superconducting gap determined from scanning tunneling microscopy for CeCoIn$_5$, we conclude the robust upward dispersing resonance mode in Ce$_{1-x}$Yb$_{x}$CoIn$_5$ is inconsistent with the downward dispersion predicted within the spin-exciton scenario.Comment: Supplementary Information available upon reques

Nature of the spin resonance mode in CeCoIn5_5

Spin-fluctuation-mediated unconventional superconductivity can emerge at the border of magnetism, featuring a superconducting order parameter that changes sign in momentum space. Detection of such a sign-change is experimentally challenging, since most probes are not phase-sensitive. The observation of a spin resonance mode (SRM) from inelastic neutron scattering is often seen as strong phase-sensitive evidence for a sign-changing superconducting order parameter, by assuming the SRM is a spin-excitonic bound state. Here, we show that for the heavy fermion superconductor CeCoIn$_5$, its SRM defies expectations for a spin-excitonic bound state, and is not a manifestation of sign-changing superconductivity. Instead, the SRM in CeCoIn$_5$ likely arises from a reduction of damping to a magnon-like mode in the superconducting state, due to its proximity to magnetic quantum criticality. Our findings emphasize the need for more stringent tests of whether SRMs are spin-excitonic, when using their presence to evidence sign-changing superconductivity.Comment: accepted for publication in Communications Physic

Magnetic excitations of the charge stripe electrons below half doping in La2−xSrxNiO4 (x = 0.45, 0.4)

The low energy magnetic excitation spectrum of charge stripe ordered La2−xSrxNiO4, x = 0.4 and x = 0.45 were studied by neutron scattering. Two excitation modes are observed in both materials, one from the ordered magnetic moments, and a second mode consistent with pseudo-onedimensional antiferromagnetic excitations of the charge stripe electrons (q-1D). The dispersion of the q-1D excitation follows the same relation as in x = 1/3 composition, with even spectral weight in the two counter-propagating branches of the x = 0.4, however in the x = 0.45 only one dispersion branch has any measurable spectral weight. The evolution of the q-1D excitations on doping to the checkerboard charge ordered phase is discussed

Wind engineering study of the Interama Tower of the Sun

CER74-75JAP-JEC23.Includes bibliographical references (pages 34-35).January 1975.For Ferendino-Grafton-Spillis-Candela.Support for this investigation was provided by Ferendino-Grafton-Spillis-Candela Architects and the Interama Authority of Miami

Loss of Cathepsin B and L Leads to Lysosomal Dysfunction, NPC-Like Cholesterol Sequestration and Accumulation of the Key Alzheimer's Proteins

Proper function of lysosomes is particularly important in neurons, as they cannot dilute accumulated toxic molecules and aggregates by cell division. Thus, impairment of lysosomal function plays an important role in neuronal degeneration and in the pathogenesis of numerous neurodegenerative diseases. In this work we analyzed how inhibition and/or loss of the major lysosomal proteases, the cysteine cathepsins B and L (CtsB/L), affects lysosomal function, cholesterol metabolism and degradation of the key Alzheimer's disease (AD) proteins. Here, we show that cysteine CtsB/L, and not the aspartyl cathepsin D (CtsD), represent a major lysosomal protease(s) that control lysosomal function, intracellular cholesterol trafficking and AD-like amyloidogenic features. Intriguingly, accumulation of free cholesterol in late endosomes/lysosomes upon CtsB/L inhibition resembled a phenotype characteristic for the rare neurodegenerative disorder Niemann-Pick type C (NPC). CtsB/L inhibition and not the inhibition of CtsD led to lysosomal impairment assessed by decreased degradation of EGF receptor, enhanced LysoTracker staining and accumulation of several lysosomal proteins LC3II, NPC1 and NPC2. By measuring the levels of NPC1 and ABCA1, the two major cholesterol efflux proteins, we showed that CtsB/L inhibition or genetic depletion caused accumulation of the NPC1 in lysosomes and downregulation of ABCA1 protein levels and its expression. Furthermore, we revealed that CtsB/L are involved in degradation of the key Alzheimer’s proteins: amyloid-β peptides (Aβ) and C-terminal fragments of the amyloid precursor protein (APP) and in degradation of β-secretase (BACE1). Our results imply CtsB/L as major regulators of lysosomal function and demonstrate that CtsB/L may play an important role in intracellular cholesterol trafficking and in degradation of the key AD proteins. Our findings implicate that enhancing the activity or levels of CtsB/L could provide a promising and a common strategy for maintaining lysosomal function and for preventing and/or treating neurodegenerative diseases

From the zero-field metal-insulator transition in two dimensions to the quantum Hall transition: a percolation-effective-medium theory

Effective-medium theory is applied to the percolation description of the metal-insulator transition in two dimensions with emphasis on the continuous connection between the zero-magnetic-field transition and the quantum Hall transition. In this model the system consists of puddles connected via saddle points, and there is loss of quantum coherence inside the puddles. The effective conductance of the network is calculated using appropriate integration over the distribution of conductances, leading to a determination of the magnetic field dependence of the critical density. Excellent quantitative agreement is obtained with the experimental data, which allows an estimate of the puddle physical parameters