Impact of Precipitating Electrons and Magnetosphere-Ionosphere Coupling Processes on Ionospheric Conductance

Modeling of electrodynamic coupling between the magnetosphere and ionosphere depends on accurate specification of ionospheric conductances produced by auroral electron precipitation. Magnetospheric models determine the plasma properties on magnetic field lines connected to the auroral ionosphere, but the precipitation of energetic particles into the ionosphere is the result of a two step process. The first step is the initiation of electron precipitation into both magnetic conjugate points from Earths plasma sheet via wave-particle interactions. The second step consists of the multiple atmospheric reflections of electrons at the two magnetic conjugate points, which produces secondary superthermal electron fluxes. The steady state solution for the precipitating particle fluxes into the ionosphere differs significantly from that calculated based on the originating magnetospheric population predicted by MHD and ring current kinetic models. Thus, standard techniques for calculating conductances from the mean energy and energy flux of precipitating electrons in model simulations must be modified to account for these additional processes. Here we offer simple parametric relations for calculating Pedersen and Hall height-integrated conductances that include the contributions from superthermal electrons produced by magnetosphere-ionosphere-atmosphere coupling in the auroral regions

Influence of Beef Production System on Calpain-1 Autolysis and Troponin-T Degradation

The objective of this study was to determine the impact beef production systems utilizing different levels of growth promotant technology on calpain-1 autolysis and troponin-T degradation, which are measures of tenderness

Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry

We present transport measurements of a tunable silicon metal-oxide-semiconductor double quantum dot device with lateral geometry. Experimentally extracted gate-to-dot capacitances show that the device is largely symmetric under the gate voltages applied. Intriguingly, these gate voltages themselves are not symmetric. Comparison with numerical simulations indicates that the applied gate voltages serve to offset an intrinsic asymmetry in the physical device. We also show a transition from a large single dot to two well isolated coupled dots, where the central gate of the device is used to controllably tune the interdot coupling.Comment: 4 pages, 3 figures, to be published in Applied Physics Letter

Scalable and Interpretable One-class SVMs with Deep Learning and Random Fourier features

One-class support vector machine (OC-SVM) for a long time has been one of the most effective anomaly detection methods and extensively adopted in both research as well as industrial applications. The biggest issue for OC-SVM is yet the capability to operate with large and high-dimensional datasets due to optimization complexity. Those problems might be mitigated via dimensionality reduction techniques such as manifold learning or autoencoder. However, previous work often treats representation learning and anomaly prediction separately. In this paper, we propose autoencoder based one-class support vector machine (AE-1SVM) that brings OC-SVM, with the aid of random Fourier features to approximate the radial basis kernel, into deep learning context by combining it with a representation learning architecture and jointly exploit stochastic gradient descent to obtain end-to-end training. Interestingly, this also opens up the possible use of gradient-based attribution methods to explain the decision making for anomaly detection, which has ever been challenging as a result of the implicit mappings between the input space and the kernel space. To the best of our knowledge, this is the first work to study the interpretability of deep learning in anomaly detection. We evaluate our method on a wide range of unsupervised anomaly detection tasks in which our end-to-end training architecture achieves a performance significantly better than the previous work using separate training.Comment: Accepted at European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML-PKDD) 201

Probing Stereoselectivity in Ring-Opening Metathesis Polymerization Mediated by Cyclometalated Ruthenium-Based Catalysts: A Combined Experimental and Computational Study

The microstructures of polymers produced by ring-opening metathesis polymerization (ROMP) with cyclometalated Ru-carbene metathesis catalysts were investigated. A strong bias for a cis,syndiotactic microstructure with minimal head-to-tail bias was observed. In instances where trans errors were introduced, it was determined that these regions were also syndiotactic. Furthermore, hypothetical reaction intermediates and transition structures were analyzed computationally. Combined experimental and computational data support a reaction mechanism in which cis,syndio-selectivity is a result of stereogenic metal control, while microstructural errors are predominantly due to alkylidene isomerization via rotation about the Ru═C double bond

Enhancement mode double top gated MOS nanostructures with tunable lateral geometry

We present measurements of silicon (Si) metal-oxide-semiconductor (MOS) nanostructures that are fabricated using a process that facilitates essentially arbitrary gate geometries. Stable Coulomb blockade behavior free from the effects of parasitic dot formation is exhibited in several MOS quantum dots with an open lateral quantum dot geometry. Decreases in mobility and increases in charge defect densities (i.e. interface traps and fixed oxide charge) are measured for critical process steps, and we correlate low disorder behavior with a quantitative defect density. This work provides quantitative guidance that has not been previously established about defect densities for which Si quantum dots do not exhibit parasitic dot formation. These devices make use of a double-layer gate stack in which many regions, including the critical gate oxide, were fabricated in a fully-qualified CMOS facility.Comment: 11 pages, 6 figures, 3 tables, accepted for publication in Phys. Rev.

Solar cell efficiency enhancement via light trapping in printable resonant dielectric nanosphere arrays

Resonant dielectric structures are a promising platform for addressing the key challenge of light trapping in thin-film solar cells. We experimentally and theoretically demonstrate efficiency enhancements in solar cells from dielectric nanosphere arrays. Two distinct amorphous silicon photovoltaic architectures were improved using this versatile light-trapping platform. In one structure, the colloidal monolayer couples light into the absorber in the near-field acting as a photonic crystal light-trapping element. In the other, it acts in the far-field as a graded index antireflection coating to further improve a cell which already included a state-of-the-art random light-trapping texture to achieve a conversion efficiency over 11%. For the near-field flat cell architecture, we directly fabricated the colloidal monolayer on the device through Langmuir–Blodgett deposition in a scalable process that does not degrade the active material. In addition, we present a novel transfer printing method, which utilizes chemical crosslinking of an optically thin adhesion layer to tether sphere arrays to the device surface. The minimally invasive processing conditions of this transfer method enable the application to a wide range of solar cells and other optoelectronic devices. False-color SEM image of an amorphous silicon solar cell with resonant spheres on top

Thermomechanical Behavior and Local Dynamics of Dendronized Block Copolymers and Constituent Homopolymers

We employ Brillouin light scattering (BLS) and dielectic spectroscopy (DS) to study the phononic behavior, thermomechanical properties, and segmental dynamics of symmetric block copolymers (BCP) constructed from discrete wedge-type repeat units and the corresponding dendronized constituent homopolymers over a broad temperature range. In spite of the sufficiently large elastic contrast between the bulk homopolymers, for the BCPs an absence of a bandgap in the phonon dispersion relation along the periodicity direction implies different modified sound velocities in the photonic BCP lamellar films. The anticipated rich segmental dynamics reveal interfacial mixing as well as confinement effects of the two blocks. This class of amorphous dendronized homopolymers and BCPs reveal strong effects of the wedge-like side groups manifested in the vastly different glass transition temperatures (T_g), free-volume domination of the temperature dependence of the elastic modulus, and heterogeneous segmental dynamics represented by four relaxation processes