72,131 research outputs found
Transverse Spin Structure of the Nucleon through Target Single Spin Asymmetry in Semi-Inclusive Deep-Inelastic Reaction at Jefferson Lab
Jefferson Lab (JLab) 12 GeV energy upgrade provides a golden opportunity to
perform precision studies of the transverse spin and
transverse-momentum-dependent structure in the valence quark region for both
the proton and the neutron. In this paper, we focus our discussion on a
recently approved experiment on the neutron as an example of the precision
studies planned at JLab. The new experiment will perform precision measurements
of target Single Spin Asymmetries (SSA) from semi-inclusive electro-production
of charged pions from a 40-cm long transversely polarized He target in
Deep-Inelastic-Scattering kinematics using 11 and 8.8 GeV electron beams. This
new coincidence experiment in Hall A will employ a newly proposed solenoid
spectrometer (SoLID). The large acceptance spectrometer and the high polarized
luminosity will provide precise 4-D (, , and ) data on the
Collins, Sivers, and pretzelocity asymmetries for the neutron through the
azimuthal angular dependence. The full 2 azimuthal angular coverage in the
lab is essential in controlling the systematic uncertainties. The results from
this experiment, when combined with the proton Collins asymmetry measurement
and the Collins fragmentation function determined from the ee collision
data, will allow for a quark flavor separation in order to achieve a
determination of the tensor charge of the d quark to a 10% accuracy. The
extracted Sivers and pretzelocity asymmetries will provide important
information to understand the correlations between the quark orbital angular
momentum and the nucleon spin and between the quark spin and nucleon spin.Comment: 23 pages, 13 figures, minor corrections, matches published versio
Taste or Addiction?: Using Play Logs to Infer Song Selection Motivation
Online music services are increasing in popularity. They enable us to analyze
people's music listening behavior based on play logs. Although it is known that
people listen to music based on topic (e.g., rock or jazz), we assume that when
a user is addicted to an artist, s/he chooses the artist's songs regardless of
topic. Based on this assumption, in this paper, we propose a probabilistic
model to analyze people's music listening behavior. Our main contributions are
three-fold. First, to the best of our knowledge, this is the first study
modeling music listening behavior by taking into account the influence of
addiction to artists. Second, by using real-world datasets of play logs, we
showed the effectiveness of our proposed model. Third, we carried out
qualitative experiments and showed that taking addiction into account enables
us to analyze music listening behavior from a new viewpoint in terms of how
people listen to music according to the time of day, how an artist's songs are
listened to by people, etc. We also discuss the possibility of applying the
analysis results to applications such as artist similarity computation and song
recommendation.Comment: Accepted by The 21st Pacific-Asia Conference on Knowledge Discovery
and Data Mining (PAKDD 2017
A methodology for low-speed broadband rotational energy harvesting using piezoelectric transduction and frequency up-conversion
Energy harvesting from vibration for low-power electronics has been investigated intensively in recent years, but rotational energy harvesting is less investigated and still has some challenges. In this paper, a methodology for low-speed rotational energy harvesting using piezoelectric transduction and frequency up-conversion is analysed. The system consists of a piezoelectric cantilever beam with a tip magnet and a rotating magnet on a revolving host. The angular kinetic energy of the host is transferred to the vibration energy of the piezoelectric beam via magnetic coupling between the magnets. Frequency up-conversion is achieved by magnetic plucking, converting low frequency rotation into high frequency vibration of the piezoelectric beam. A distributed-parameter theoretical model is presented to analyse the electromechanical behaviour of the rotational energy harvester. Different configurations and design parameters were investigated to improve the output power of the device. Experimental studies were conducted to validate the theoretical estimation. The results illustrate that the proposed method is a feasible solution to collecting low-speed rotational energy from ambient hosts, such as vehicle tires, micro-turbines and wristwatches
Nanofiller-tuned microporous polymer molecular sieves for energy and environmental processes
10.1039/c5ta09060aJournal of Materials Chemistry A41270-27
A distinct sortase SrtB anchors and processes a streptococcal adhesin AbpA with a novel structural property.
Surface display of proteins by sortases in Gram-positive bacteria is crucial for bacterial fitness and virulence. We found a unique gene locus encoding an amylase-binding adhesin AbpA and a sortase B in oral streptococci. AbpA possesses a new distinct C-terminal cell wall sorting signal. We demonstrated that this C-terminal motif is required for anchoring AbpA to cell wall. In vitro and in vivo studies revealed that SrtB has dual functions, anchoring AbpA to the cell wall and processing AbpA into a ladder profile. Solution structure of AbpA determined by NMR reveals a novel structure comprising a small globular α/β domain and an extended coiled-coil heliacal domain. Structural and biochemical studies identified key residues that are crucial for amylase binding. Taken together, our studies document a unique sortase/adhesion substrate system in streptococci adapted to the oral environment rich in salivary amylase
Structural optimization and biological evaluation of 2-substituted 5-hydroxyindole-3-carboxylates as potent inhibitors of human 5-lipoxygenase.
Pharmacological suppression of leukotriene biosynthesis by inhibitors of 5-lipoxygenase (5-LO) is a strategy to intervene with inflammatory and allergic disorders. We recently presented 2-amino-5-hydroxy-1H-indoles as efficient 5-LO inhibitors in cell-based and cell-free assays. Structural optimization led to novel benzo[g]indole-3-carboxylates exemplified by ethyl 2-(3-chlorobenzyl)-5- hydroxy-1H-benzo[g]indole-3-carboxylate (compound 11a), which inhibits 5-LO activity in human neutrophils and recombinant human 5-LO with IC50 values of 0.23 and 0.086 μM, respectively. Notably, 11a efficiently blocks 5-LO product formation in human whole blood assays (IC50 = 0.83-1.6 μM) and significantly prevented leukotriene B4 production in pleural exudates of carrageenan-treated rats, associated with reduced severity of pleurisy. Together, on the basis of their high potency against 5-LO and the marked efficacy in biological systems, these novel and straightforward benzo[g]indole-3-carboxylates may have potential as anti-inflammatory therapeutics
Supersolutions for a class of semilinear heat equations
A semilinear heat equation with nonnegative initial
data in a subset of is considered under the assumption that
is nonnegative and nondecreasing and . A simple
technique for proving existence and regularity based on the existence of
supersolutions is presented, then a method of construction of local and global
supersolutions is proposed. This approach is applied to the model case
, : new sufficient conditions for the
existence of local and global classical solutions are derived in the critical
and subcritical range of parameters. Some possible generalisations of the
method to a broader class of equations are discussed.Comment: Expanded version of the previous submission arXiv:1111.0258v1. 14
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Heliotracking Device using Liquid Crystalline Elastomer Actuators
Many living organisms in nature respond to light stimulus and track the light source. Inspired by this, and to maximize the light-harvesting ability of solar cells, here, a spontaneous helio-tracking device based on the differential light-induced actuation of liquid crystalline elastomers (LCEs) is demonstrated. The synthesis of the actuator material involves a robust thiol “click” polymerization, while the addition of indocyanine green (ICG) dye imparts the sensitivity to broad-spectrum and near-infrared light. Highly reproducible thermal and photo-induced linear actuation is demonstrated. The device is based on a freely pivoting payload platform held in place by several linear LCE actuators around the 360° circumference. The side of the device, which is exposed to light, has the actuators contracting and tilting the platform toward the light source. As the light source (e.g., the Sun) is moving around the device, the platform tilt followed, always exposing the payload face to the light; in the dark, the device recovers its neutral position
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