1,739 research outputs found
Particle Matter Measurements for Inspection/Maintenance Programs
Particle emissions from Heavy Duty Diesel Vehicles (HDDVs) are currently measured by opacity or dynamometer gravimetric analysis. The Electronic Tailpipe Particle Sensor (ETaPS) is an inexpensive measurement device purported to give real time response to particle mass and was proposed as a possible addition to Inspection/Maintenance (I/M) programs. There were three goals to this study. The first was to verify ETaPS response to particle mass of HDDV exhaust. Integrated ETaPS signal was plotted against filter weight from dynamometer gravimetric analysis and a correlation was found. The second goal was to find a correlation between ETaPS readings and the Remote Sensing Detector (RSD). These tests were invalidated due to interference from power lines greatly affecting the ETaPS signal. The final goal was to find a relationship between the RSD and the dynamometer gravimetric analysis. Comparisons were made from averaged RSD smoke data, and averaged gravimetric data for each HDDV undergoing both tests. A measurable difference was found for RSD smoke readings between Diesel Particle Filter (DPF) equipped vs. non-DPF and DPF bypassed HDDVs
Surface And Interfacial Alloys Of Palladium With Copper(100): Structure, Chemistry, And Kinematics
The interaction between Pd and the Cu(100) surface has been studied by surface science techniques. When Pd is evaporated onto Cu(100) at 110 K, small Pd islands form on the surface. At substrate temperatures above approximately 180 K, mixed Pd-Cu interfacial layers form. For Pd deposition at 300 K, c(2x2) and p4g surface alloy structures form near 0.5 and 1.0 monolayer (ML) Pd coverage respectively. Above one ML, disordered Pd overlayers form. The surface alloy structures are metastable only, since heating irreversibly segregates Cu to the surface.;The chemistry of the Pd and Cu atoms in the interfacial layers is changed with respect to the pure metals. Changes in their CO chemisorption properties correlate with shifts in the valence band and core level spectra. The core level binding energy shifts are consistent with charge transfer from Pd to Cu. The valence band spectra show a Pd derived feature 1.6 eV below the Fermi level characteristic of Pd in a Cu matrix.;The kinetics of formation of the c(2x2) surface alloy from adsorbed Pd has been studied. The domain growth is self-similar, and the development of order is well described by an exponential growth law. The measured growth exponent and activation energy for ordering are 1/8 and {dollar}\approx{dollar}0.9 eV respectively. The activation barrier to concerted Pd-Cu place exchange is {dollar}\approx{dollar}0.34 eV
Polynuclear Ruthenium Amines Inhibit K2P Channels via a "Finger in the Dam" Mechanism
The trinuclear ruthenium amine ruthenium red (RuR) inhibits diverse ion channels, including K2P potassium channels, TRPs, the calcium uniporter, CALHMs, ryanodine receptors, and Piezos. Despite this extraordinary array, there is limited information for how RuR engages targets. Here, using X-ray crystallographic and electrophysiological studies of an RuR-sensitive K2P, K2P2.1 (TREK-1) I110D, we show that RuR acts by binding an acidic residue pair comprising the "Keystone inhibitor site" under the K2P CAP domain archway above the channel pore. We further establish that Ru360, a dinuclear ruthenium amine not known to affect K2Ps, inhibits RuR-sensitive K2Ps using the same mechanism. Structural knowledge enabled a generalizable design strategy for creating K2P RuR "super-responders" having nanomolar sensitivity. Together, the data define a "finger in the dam" inhibition mechanism acting at a novel K2P inhibitor binding site. These findings highlight the polysite nature of K2P pharmacology and provide a new framework for K2P inhibitor development
Generalized Dualities and Supergroups
Using a recently developed formulation of double field theory in superspace,
the graviton, -field, gravitini, dilatini, and Ramond-Ramond bispinor are
encoded in a single generalized supervielbein. Duality transformations are
encoded as orthosymplectic transformations, extending the bosonic
duality group, and these act on all constituents of the supervielbein in an
easily computable way. We first review conventional non-abelian T-duality in
the Green-Schwarz superstring and describe the dual geometries in the language
of double superspace. Since dualities are related to super-Killing vectors,
this includes as special cases both abelian and non-abelian fermionic
T-duality.
We then extend this approach to include Poisson-Lie T-duality and its
generalizations, including the generalized coset construction recently
discussed in arXiv:1912.11036. As an application, we construct the
supergeometries associated with the integrable and
deformations of the superstring. The deformation parameters
and are identified with the possible one-parameter embeddings
of the supergravity frame within the doubled supergeometry. In this framework,
the Ramond-Ramond bispinors are directly computable purely from the algebraic
data of the supergroup.Comment: 85 pages; v2: references added, additional comments in introduction
and conclusio
Consistent Truncations and Dualities
Recent progress in generalised geometry and extended field theories suggests
a deep connection between consistent truncations and dualities, which is not
immediately obvious. A prime example is generalised Scherk-Schwarz reductions
in double field theory, which have been shown to be in one-to-one
correspondence with Poisson-Lie T-duality. Here we demonstrate that this
relation is only the tip of the iceberg. Currently, the most general known
classes of T-dualities (excluding mirror symmetry) are based on dressing
cosets. But as we discuss, they can be further extended to the even larger
class of generalised cosets. We prove that the latter give rise to consistent
truncations for which the ansatz can be constructed systematically. Hence, we
pave the way for many new examples of T-dualities and consistent truncations.
The arising structures result in covariant tensors with more than two
derivatives and we argue how they might be key to understand generalised
T-dualities and consistent truncations beyond the leading two derivative level.Comment: 43 page
Examining the Environmental Impacts of the Dairy and Baby Food Industries: Are First-Food Systems a Crucial Missing Part of the Healthy and Sustainable Food Systems Agenda Now Underway?
Food systems are increasingly being understood as driving various health and ecological crises and their transformation is recognised as a key opportunity for planetary health. First-food systems represent an underexplored aspect of this transformation. Despite breastfeeding representing the optimal source of infant nutrition, use of commercial milk formula (CMF) is high and growing rapidly. In this review, we examine the impact of CMF use on planetary health, considering in particular its effects on climate change, water use and pollution and the consequences of these effects for human health. Milk is the main ingredient in the production of CMF, making the role of the dairy sector a key area of attention. We find that CMF use has twice the carbon footprint of breastfeeding, while 1 kg of CMF has a blue water footprint of 699 L; CMF has a significant and harmful environmental impact. Facilitation and protection of breastfeeding represents a key part of developing sustainable first-food systems and has huge potential benefits for maternal and child health
Whisker's Directional Selectivity: Orientation Columns in the Barrel Field?
Using voltage-sensitive dye optical imaging methods, we visualized neural activity in the rat barrel cortex in response to the deflection of a single whisker in different directions. Obtained data indicates that fast movements of single whiskers in varying directions correlate with different patterns of activation in the somatosensory cortex. A functional map was created based on the voltage-sensitive dye optical signal. This supports prior research that vibrissae deflections cause responses in different cortical neurons within the barrel field according to the direction of the deflection. By analogy with the orientation columns in the visual cortex, directionally-biased single whisker responses to different directions of deflection could be a possible mechanism for the directional selectivity of this important sensory response
The Universe at Extreme Scale: Multi-Petaflop Sky Simulation on the BG/Q
Remarkable observational advances have established a compelling
cross-validated model of the Universe. Yet, two key pillars of this model --
dark matter and dark energy -- remain mysterious. Sky surveys that map billions
of galaxies to explore the `Dark Universe', demand a corresponding
extreme-scale simulation capability; the HACC (Hybrid/Hardware Accelerated
Cosmology Code) framework has been designed to deliver this level of
performance now, and into the future. With its novel algorithmic structure,
HACC allows flexible tuning across diverse architectures, including accelerated
and multi-core systems.
On the IBM BG/Q, HACC attains unprecedented scalable performance -- currently
13.94 PFlops at 69.2% of peak and 90% parallel efficiency on 1,572,864 cores
with an equal number of MPI ranks, and a concurrency of 6.3 million. This level
of performance was achieved at extreme problem sizes, including a benchmark run
with more than 3.6 trillion particles, significantly larger than any
cosmological simulation yet performed.Comment: 11 pages, 11 figures, final version of paper for talk presented at
SC1
Optical Imaging of Interaural Time Difference Representation in Rat Auditory Cortex
We used in vivo voltage-sensitive dye optical imaging to examine the cortical representation of interaural time difference (ITD), which is believed to be involved in sound source localization. We found that acoustic stimuli with dissimilar ITD activate various localized domains in the auditory cortex. The main loci of the activation pattern shift up to 1 mm during the first 40 ms of the response period. We suppose that some of the neurons in each pool are sensitive to the definite ITD and involved in the transduction of information about sound source localization, based on the ITD. This assumption gives a reasonable fit to the Jeffress model in which the neural network calculates the ITD to define the direction of the sound source. Such calculation forms the basis for the cortex's ability to detect the azimuth of the sound source
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