358 research outputs found
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Magnetosensitive e-skins with directional perception for augmented reality
Electronic skins equipped with artificial receptors are able to extend our perception beyond the modalities that have naturally evolved. These synthetic receptors offer complimentary information on our surroundings and endow us with novel means of manipulating physical or even virtual objects. We realize highly compliant magnetosensitive skins with directional perception that enable magnetic cognition, body position tracking, and touchless object manipulation. Transfer printing of eight high-performance spin valve sensors arranged into two Wheatstone bridges onto 1.7-mm-thick polyimide foils ensures mechanical imperceptibility. This resembles a new class of interactive devices extracting information from the surroundings through magnetic tags. We demonstrate this concept in augmented reality systems with virtual knob-turning functions and the operation of virtual dialing pads, based on the interaction with magnetic fields. This technology will enable a cornucopia of applications from navigation, motion tracking in robotics, regenerative medicine, and sports and gaming to interaction in supplemented reality
Irreducible Multiplets of Three-Quark Operators on the Lattice: Controlling Mixing under Renormalization
High luminosity accelerators have greatly increased the interest in
semi-exclusive and exclusive reactions involving nucleons. The relevant
theoretical information is contained in the nucleon wavefunction and can be
parametrized by moments of the nucleon distribution amplitudes, which in turn
are linked to matrix elements of three-quark operators. These can be calculated
from first principles in lattice QCD. However, on the lattice the problems of
operator mixing under renormalization are rather involved. In a systematic
approach we investigate this issue in depth. Using the spinorial symmetry group
of the hypercubic lattice we derive irreducibly transforming three-quark
operators, which allow us to control the mixing pattern.Comment: 13 page
The Impact of Geographic Distance on Online Social Interactions
Online social networking services entice millions of users to spend hours every day interacting with each other. The focus of this work is to explain the effect that geographic distance has on online social interactions and, simultaneously, to understand the interplay between the social characteristics of friendship ties and their spatial properties. We analyze data from a large-scale online social network, Tuenti, with about 10 million active users: our sample includes user profiles, user home locations and online social interactions among Tuenti members. Our findings support the idea that spatial distance constraints whom users interact with, but not the intensity of their social interactions. Furthermore, friendship ties belonging to denser connected groups tend to arise at shorter spatial distances than social ties established between members belonging to different groups. Finally, we show that our findings mostly do not depend on the age of the users, although younger users seem to be slightly more constrained to shorter geographic distances. Augmenting social structure with geographic information adds a new dimension to social network analysis and a large number of theoretical investigations and practical applications can be pursued for online social systems, with many promising outcomes. As the amount of available location-based data is increasing, our findings and results open the door to future possibilities: researchers would benefit from these insights when studying online social services, while developers should be aware of these additional possibilities when building systems and applications related to online social platforms
Designing Ultraflexible Perovskite X-Ray Detectors through Interface Engineering
X-ray detectors play a pivotal role in development and advancement of humankind, from far-reaching impact in medicine to furthering the ability to observe distant objects in outer space. While other electronics show the ability to adapt to flexible and lightweight formats, state-of-the-art X-ray detectors rely on materials requiring bulky and fragile configurations, severely limiting their applications. Lead halide perovskites is one of the most rapidly advancing novel materials with success in the field of semiconductor devices. Here, an ultraflexible, lightweight, and highly conformable passively operated thin film perovskite X-ray detector with a sensitivity as high as 9.3 ± 0.5 µC Gy−1 cm−2 at 0 V and a remarkably low limit of detection of 0.58 ± 0.05 μGy s−1 is presented. Various electron and hole transporting layers accessing their individual impact on the detector performance are evaluated. Moreover, it is shown that this ultrathin form-factor allows for fabrication of devices detecting X-rays equivalently from front and back side
SRG/eROSITA-triggered XMM-Newton observations of three Be/X-ray binaries in the LMC: Discovery of X-ray pulsations
Using data from eROSITA, the soft X-ray instrument aboard
Spectrum-Roentgen-Gamma (SRG), we report the discovery of two new hard
transients, eRASSU J050810.4-660653 and eRASSt J044811.1-691318, in the Large
Magellanic Cloud. We also report the detection of the Be/X-ray binary RX
J0501.6-7034 in a bright state. We initiated follow-up observations to
investigate the nature of the new transients and to search for X-ray pulsations
coming from RX J0501.6-7034. We analysed the X-ray spectra and light curves
from our XMM-Newton observations, obtained optical spectra using the South
African Large Telescope to look for Balmer emission lines and utilised the
archival data from the Optical Gravitational Lensing Experiment (OGLE) for the
long-term monitoring of the optical counterparts. We find X-ray pulsations for
eRASSU J050810.4-660653, RX J0501.6-7034, and eRASSt J044811.1-691318 of 40.6
s, 17.3 s, and 784 s, respectively. The Halpha emission lines with equivalent
widths of -10.4 A (eRASSU J050810.4-660653) and -43.9 A (eRASSt
J044811.1-691318) were measured, characteristic for a circumstellar disc around
Be stars. The OGLE I- and V-band light curves of all three systems exhibit
strong variability. A regular pattern of deep dips in the light curves of RX
J0501.6-7034 suggests an orbital period of ~451 days. We identify the two new
hard eROSITA transients eRASSU J050810.4-660653 and eRASSt J044811.1-691318 and
the known Be/X-ray binary RX J0501.6-7034 as Be/X-ray binary pulsars.Comment: Accepted for publication in Astronomy & Astrophysic
Non-perturbative improvement of stout-smeared three flavour clover fermions
We discuss a 3-flavour lattice QCD action with clover improvement in which
the fermion matrix has single level stout smearing for the hopping terms
together with unsmeared links for the clover term. With the (tree-level)
Symanzik improved gluon action this constitutes the Stout Link Non-perturbative
Clover or SLiNC action. To cancel O(a) terms the clover term coefficient has to
be tuned. We present here results of a non-perturbative determination of this
coefficient using the Schroedinger functional and as a by-product a
determination of the critical hopping parameter. Comparisons of the results are
made with lowest order perturbation theory.Comment: 30 pages, 13 figures, minor changes, published versio
Development of Photonic Crystal Fiber Based Gas/ Chemical Sensors
The development of highly-sensitive and miniaturized sensors that capable of
real-time analytes detection is highly desirable. Nowadays, toxic or colorless
gas detection, air pollution monitoring, harmful chemical, pressure, strain,
humidity, and temperature sensors based on photonic crystal fiber (PCF) are
increasing rapidly due to its compact structure, fast response and efficient
light controlling capabilities. The propagating light through the PCF can be
controlled by varying the structural parameters and core-cladding materials, as
a result, evanescent field can be enhanced significantly which is the main
component of the PCF based gas/chemical sensors. The aim of this chapter is to
(1) describe the principle operation of PCF based gas/ chemical sensors, (2)
discuss the important PCF properties for optical sensors, (3) extensively
discuss the different types of microstructured optical fiber based gas/
chemical sensors, (4) study the effects of different core-cladding shapes, and
fiber background materials on sensing performance, and (5) highlight the main
challenges of PCF based gas/ chemical sensors and possible solutions
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