The design and implementation of partnet

Journal ArticlePartNet is a federated database for providing interactive online access to mechanical parts catalogs. The data contained in the vendor's product database is exported to the federated database using a networkbased distributed database protocol. A Single coherent view of these vendor databases is provided by a Query Server which clients access to pose queries and receive answers. The client interface programs are simple and can be executed on current desktop computers. The system is scaleable to thousands of vendors and tens of thousands of customers. We feel this approach provides better service at less cost than traditional paper or CD ROM catalogs

Associated hyperon-kaon production via neutrino-nucleus scattering

We present the investigation of the neutrino-induced strangeness associated production on nuclei in the relativistic plane wave impulse approximation (RPWIA) framework at the intermediate neutrino energies. In this study, the elementary hadronic weak amplitudes are embedded inside the nuclear medium for the description of the exclusive channels of neutrino-nucleus interactions. These amplitudes are extracted using a model-dependent evaluation of the hadronic vertex using the Born term approximation in which the application of the Cabibbo V-A theory and SU(3) symmetry are assumed to be valid. The nuclear effects are included via the bound state wavefunctions of the nucleon obtained from the relativistic mean field (RMF) models. Two kinematics settings are used to examine various distributions of the differential cross section in the rest frame of the target nuclei. The numerical results are obtained for the neutrino-induced charged-current (CC) \,$\rm K^{^+}\Lambda$-production on bound neutrons in $1s^{1/2}$ and $1p^{3/2}$ orbitals of $^{12}$C. The angular distributions are forward peaked under both kinematic settings, whereas under the quasifree setting the cross sections tend mimic the missing momentum distribution of the bound nucleon inside the nucleus.Comment: This article is submitted to International Journal of Modern Physics E (nuclear physics) and accepted on 31 October 20l

Dark-field transmission electron microscopy and the Debye-Waller factor of graphene

Graphene's structure bears on both the material's electronic properties and fundamental questions about long range order in two-dimensional crystals. We present an analytic calculation of selected area electron diffraction from multi-layer graphene and compare it with data from samples prepared by chemical vapor deposition and mechanical exfoliation. A single layer scatters only 0.5% of the incident electrons, so this kinematical calculation can be considered reliable for five or fewer layers. Dark-field transmission electron micrographs of multi-layer graphene illustrate how knowledge of the diffraction peak intensities can be applied for rapid mapping of thickness, stacking, and grain boundaries. The diffraction peak intensities also depend on the mean-square displacement of atoms from their ideal lattice locations, which is parameterized by a Debye-Waller factor. We measure the Debye-Waller factor of a suspended monolayer of exfoliated graphene and find a result consistent with an estimate based on the Debye model. For laboratory-scale graphene samples, finite size effects are sufficient to stabilize the graphene lattice against melting, indicating that ripples in the third dimension are not necessary.Comment: 10 pages, 4 figure

Polarized light emission from individual incandescent carbon nanotubes

We fabricate nanoscale lamps which have a filament consisting of a single multiwalled carbon nanotube. After determining the nanotube geometry with a transmission electron microscope, we use Joule heating to bring the filament to incandescence, with peak temperatures in excess of 2000 K. We image the thermal light in both polarizations simultaneously as a function of wavelength and input electrical power. The observed degree of polarization is typically of the order of 75%, a magnitude predicted by a Mie model of the filament that assigns graphene's optical conductance $\pi e^2/2 h$ to each nanotube wall.Comment: 5 pages, 4 figure

Dark-field transmission electron microscopy and the Debye-Waller factor of graphene

Graphene\u27s structure bears on both the material\u27s electronic properties and fundamental questions about long-range order in two-dimensional crystals. We present an analytic calculation of selected area electron diffraction from multilayer graphene and compare it with data from samples prepared by chemical vapor deposition and mechanical exfoliation. A single layer scatters only 0.5% of the incident electrons, so this kinematical calculation can be considered reliable for five or fewer layers. Dark-field transmission electron micrographs of multilayer graphene illustrate how knowledge of the diffraction peak intensities can be applied for rapid mapping of thickness, stacking, and grain boundaries. The diffraction peak intensities also depend on the mean-square displacement of atoms from their ideal lattice locations, which is parameterized by a Debye-Waller factor. We measure the Debye-Waller factor of a suspended monolayer of exfoliated graphene and find a result consistent with an estimate based on the Debye model. For laboratory-scale graphene samples, finite size effects are sufficient to stabilize the graphene lattice against melting, indicating that ripples in the third dimension are not necessary

Single-color pyrometry of individual incandescent multiwalled carbon nanotubes

Objects that are small compared to their thermal photon wavelengths violate the assumptions underlying optical pyrometry and can show unusual coherence effects. To investigate this regime we measure the absolute light intensity from individual, incandescent multiwalled carbon nanotubes. The nanotube filaments' physical dimensions and composition are determined using transmission electron microscopy and their emissivities are calculated in terms of bulk conductivities. A single-color pyrometric analysis then returns a temperature value for each wavelength, polarization, and applied bias measured. Compared to the more common multiwavelength analysis, single-color pyrometry supports a more consistent and complete picture of the carbon nanotube lamps, one that describes their emissivity, optical conductivity, and thermal conductivity in the range 1600-2400 K.Comment: 8 pages, 5 figure

Spacetime Noncommutativity and Antisymmetric Tensor Dynamics in the Early Universe

This paper investigates the possible cosmological implications of the presence of an antisymmetric tensor field related to a lack of commutatitivity of spacetime coordinates at the Planck era. For this purpose, such a field is promoted to a dynamical variable, inspired by tensor formalism. By working to quadratic order in the antisymmetric tensor, we study the field equations in a Bianchi I universe in two models: an antisymmetric tensor plus scalar field coupled to gravity, or a cosmological constant and a free massless antisymmetric tensor. In the first scenario, numerical integration shows that, in the very early universe, the effects of the antisymmetric tensor can prevail on the scalar field, while at late times the former approaches zero and the latter drives the isotropization of the universe. In the second model, an approximate solution is obtained of a nonlinear ordinary differential equation which shows how the mean Hubble parameter and the difference between longitudinal and orthogonal Hubble parameter evolve in the early universe.Comment: 25 pages, Revtex file, 4 figures in attachmen

Exciton swapping in a twisted graphene bilayer as a solid-state realization of a two-brane model

It is shown that exciton swapping between two graphene sheets may occur under specific conditions. A magnetically tunable optical filter is described to demonstrate this new effect. Mathematically, it is shown that two turbostratic graphene layers can be described as a "noncommutative" two-sheeted (2+1)-spacetime thanks to a formalism previously introduced for the study of braneworlds in high energy physics. The Hamiltonian of the model contains a coupling term connecting the two layers which is similar to the coupling existing between two braneworlds at a quantum level. In the present case, this term is related to a K-K' intervalley coupling. In addition, the experimental observation of this effect could be a way to assess the relevance of some theoretical concepts of the braneworld hypothesis.Comment: 15 pages, 3 figures, final version published in European Physical Journal

Systematic mechanical assessment of consolidants for canvas reinforcement under controlled environment

In conservation, adhesives are commonly used for the consolidation of canvases, yet their impact upon the canvas longevity has raised some concerns amongst conservators. As such, this study presents a testing protocol developed to assess the performance of commonly-used adhesives (natural animal glue and synthetic Beva® 371) and a newly developed nanocellulose consolidant, nanofibrillated nanocellulose (CNF). This includes their effect on the visual appearance, consolidation, and response of the mechanical properties of the treated canvases to programmed changes in relative humidity (RH). Scanning electron microscopy (SEM) images of animal glue- and Beva® 371-treated canvases revealed the presence of adhesive and consolidant on and in-between cotton fibres. The consolidants form bridges linking and connecting the cotton fibres and holding them together, whereas the CNF treatment, formed a visible continuous and dense surface coating. None of the treatments induced any discernible colour change. Controlled environment mechanical testing was performed in two ways: by applying a linearly increasing static force at fixed RH (Young’s modulus) and by applying a dynamic force together with a programmed RH cycling between 20 and 80% (RH dependent viscoelastic properties). CNF gave a higher value of Young’s modulus than either of the two commonly-used materials. Measurements at different values of RH (20 and 80%) demonstrated for all the treated canvases that at the lower value (RH 20%) Young’s modulus values were higher than at the higher value (RH 80%). Besides, the dynamic mode showed that the rate of response in all cases was rapid and reversible and that the nanofibrillated cellulose treated sample showed the highest variation in storage (or elastic) modulus measured at the end of RH plateaux (20 and 80% RH). Thus CNF appears to be a promising material given its higher mechanical performance. The protocol developed in this study has enabled us to examine and compare candidate materials for the consolidation of canvases systematically, using testing parameters that remained relevant to the field of canvas conservation

The Listening Network and Cochlear Implant Benefits in Hearing-Impaired Adults

Older adults with mild or no hearing loss make more errors and expend more effort listening to speech. Cochlear implants (CI) restore hearing to deaf patients but with limited fidelity. We hypothesized that patient-reported hearing and health-related quality of life in CI patients may similarly vary according to age. Speech Spatial Qualities (SSQ) of hearing scale and Health Utilities Index Mark III (HUI) questionnaires were administered to 543 unilaterally implanted adults across Europe, South Africa, and South America. Data were acquired before surgery and at 1, 2, and 3 years post-surgery. Data were analyzed using linear mixed models with visit, age group (18–34, 35–44, 45–54, 55–64, and 65+), and side of implant as main factors and adjusted for other covariates. Tinnitus and dizziness prevalence did not vary with age, but older groups had more preoperative hearing. Preoperatively and postoperatively, SSQ scores were significantly higher (¿0.75–0.82) for those aged <45 compared with those 55+. However, gains in SSQ scores were equivalent across age groups, although postoperative SSQ scores were higher in right-ear implanted subjects. All age groups benefited equally in terms of HUI gain (0.18), with no decrease in scores with age. Overall, younger adults appeared to cope better with a degraded hearing before and after CI, leading to better subjective hearing performance.