746 research outputs found
Taxation of Virtual Assets
The development of vast social networks through Massively Multiplayer Online Role-Playing Games has created in-game communities in which virtual assets have real-world values. The question has thus arisen whether such virtual assets are legal subjects of taxation. This iBrief will detail and discuss the various exclusions to taxable income, and analyze their application to the possibility of creating potential tax liability based on in-kind exchanges of virtual assets
Brain dynamics that correlate with effects of learning on auditory distance perception
© 2014 Wisniewski, Mercado, Church, Gramann and Makeig. Accuracy in auditory distance perception can improve with practice and varies for sounds differing in familiarity. Here, listeners were trained to judge the distances of English, Bengali, and backwards speech sources pre-recorded at near (2-m) and far (30-m) distances. Listeners' accuracy was tested before and after training. Improvements from pre-test to post-test were greater for forward speech, demonstrating a learning advantage for forward speech sounds. Independent component (IC) processes identified in electroencephalographic (EEG) data collected during pre- and post-testing revealed three clusters of ICs across subjects with stimulus-locked spectral perturbations related to learning and accuracy. One cluster exhibited a transient stimulus-locked increase in 4-8 Hz power (theta event-related synchronization; ERS) that was smaller after training and largest for backwards speech. For a left temporal cluster, 8-12 Hz decreases in power (alpha event-related desynchronization; ERD) were greatest for English speech and less prominent after training. In contrast, a cluster of IC processes centered at or near anterior portions of the medial frontal cortex showed learning-related enhancement of sustained increases in 10-16 Hz power (upper-alpha/low-beta ERS). The degree of this enhancement was positively correlated with the degree of behavioral improvements. Results suggest that neural dynamics in non-auditory cortical areas support distance judgments. Further, frontal cortical networks associated with attentional and/or working memory processes appear to play a role in perceptual learning for source distance
Overestimation of thermal emittance in solenoid scans due to coupled transverse motion
The solenoid scan is a widely used method for the in-situ measurement of the
thermal emittance in a photocathode gun. The popularity of this method is due
to its simplicity and convenience since all rf photocathode guns are equipped
with an emittance compensation solenoid. This paper shows that the solenoid
scan measurement overestimates the thermal emittance in the ordinary
measurement configuration due to a weak quadrupole field (present in either the
rf gun or gun solenoid) followed by a rotation in the solenoid. This coupled
transverse dynamics aberration introduces a correlation between the beam's
horizontal and vertical motion leading to an increase in the measured 2D
transverse emittance, thus the overestimation of the thermal emittance. This
effect was systematically studied using both analytic expressions and numerical
simulations. These studies were experimentally verified using an L-band
1.6-cell rf photocathode gun with a cesium telluride cathode, which shows a
thermal emittance overestimation of 35% with a rms laser spot size of 2.7 mm.
The paper concludes by showing that the accuracy of the solenoid scan can be
improved by using a quadrupole magnet corrector, consisting of a pair of normal
and skew quadrupole magnets.Comment: 12 pages, 13 figure
AlGaInN laser diode technology for GHz high-speed visible light communication through plastic optical fiber and water
AlGaInN ridge waveguide laser diodes are fabricated to achieve single-mode operation with optical powers up to 100 mW at ∼420  nm∼420  nm for visible free-space, underwater, and plastic optical fiber communication. We report high-frequency operation of AlGaInN laser diodes with data transmission up to 2.5 GHz for free-space and underwater communication and up to 1.38 GHz through 10 m of plastic optical fiber
Do Safety Culture Scores in Nursing Homes Depend on Job Role and Ownership? Results from a National Survey
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138839/1/jgs15030.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138839/2/jgs15030_am.pd
Observation of Skewed Electromagnetic Wakefields in an Asymmetric Structure Driven by Flat Electron Bunches
Relativistic charged-particle beams which generate intense longitudinal
fields in accelerating structures also inherently couple to transverse modes.
The effects of this coupling may lead to beam break-up instability, and thus
must be countered to preserve beam quality in applications such as linear
colliders. Beams with highly asymmetric transverse sizes (flat-beams) have been
shown to suppress the initial instability in slab-symmetric structures.
However, as the coupling to transverse modes remains, this solution serves only
to delay instability. In order to understand the hazards of transverse coupling
in such a case, we describe here an experiment characterizing the transverse
effects on a flat-beam, traversing near a planar dielectric lined structure.
The measurements reveal the emergence of a previously unobserved
skew-quadrupole-like interaction when the beam is canted transversely, which is
not present when the flat-beam travels parallel to the dielectric surface. We
deploy a multipole field fitting algorithm to reconstruct the projected
transverse wakefields from the data. We generate the effective kick vector map
using a simple two-particle theoretical model, with particle-in-cell
simulations used to provide further insight for realistic particle
distributions.Comment: Six pages, seven figures. Submitted to Physical Revie
Disk Detective: Discovery of New Circumstellar Disk Candidates through Citizen Science
The Disk Detective citizen science project aims to find new stars with 22
micron excess emission from circumstellar dust using data from NASA's WISE
mission. Initial cuts on the AllWISE catalog provide an input catalog of
277,686 sources. Volunteers then view images of each source online in 10
different bands to identify false-positives (galaxies, background stars,
interstellar matter, image artifacts, etc.). Sources that survive this online
vetting are followed up with spectroscopy on the FLWO Tillinghast telescope.
This approach should allow us to unleash the full potential of WISE for finding
new debris disks and protoplanetary disks. We announce a first list of 37 new
disk candidates discovered by the project, and we describe our vetting and
follow-up process. One of these systems appears to contain the first debris
disk discovered around a star with a white dwarf companion: HD 74389. We also
report four newly discovered classical Be stars (HD 6612, HD 7406, HD 164137,
and HD 218546) and a new detection of 22 micron excess around a previously
known debris disk host star, HD 22128.Comment: 50 pages, accepted for publication in the Astrophysical Journa
Mass spectrometry insights into a tandem ubiquitin-binding domain hybrid engineered for the selective recognition of unanchored polyubiquitin
Unanchored polyubiquitin chains are emerging as importanregulators of cellular physiology with diverse roles paralleling those of substrate-conjugated polyubiquitin. However tools able to discriminate unanchored polyubiquitin chains of different isopeptide linkages have not been described. We describe the design of a linker-optimised ubiquitin-binding domain hybrid (t-UBD) containing two UBDs, a ZnF-UBP domain in tandem with a linkage-selective UBA domain, which exploits avidity effects to afford selective recognition of unanchored Lys48-linked polyubiquitin chains. Utilising native MS to quantitatively probe binding affinities we confirm cooperative binding of the UBDs within the synthetic protein, and desired binding specificity for Lys48-linked ubiquitin dimers. Furthermore MS/MS analyses indicate that the t-UBD, when applied as an affinity enrichment reagent, can be used to favour the purification of endogenous unanchored Lys48-linked polyubiquitin chains from mammalian cell extracts. Our study indicates that strategies for the rational design and engineering of polyubiquitin chain-selective binding in non-biological polymers are possible, paving the way for the generation of reagents to probe unanchored polyubiquitin chains of different linkages and more broadly the ‘ubiquitome’
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