61,657 research outputs found
Can Universe Experience Many Cycles with Different Vacua ?
Recently, the notion that the number of vacua is enormous has received
increased attentions, which may be regarded as a possible anthropical
explanation to incredible small cosmological constant. Further, a dynamical
mechanisms to implement this possibility is required. We show in an operable
model of cyclic universe that the universe can experience many cycles with
different vacua, which is a generic behavior independent of the details of the
model. This might provide a distinct dynamical approach to an anthropically
favorable vacuum.Comment: RevTex, 10 pages, 4 eps figures, accepted by PRD(R), new title and
changes in the text to match publicatio
Quark Orbital Angular Momentum in the Baryon
Analytical and numerical results, for the orbital and spin content carried by
different quark flavors in the baryons, are given in the chiral quark model
with symmetry breaking. The reduction of the quark spin, due to the spin
dilution in the chiral splitting processes, is transferred into the orbital
motion of quarks and antiquarks. The orbital angular momentum for each quark
flavor in the proton as a function of the partition factor and the
chiral splitting probability is shown. The cancellation between the spin
and orbital contributions in the spin sum rule and in the baryon magnetic
moments is discussed.Comment: 26 pages, 3 figures, revised version with minor eq. no and ref. no.
corrections. Discussion on the spin and a new ref. are adde
Soliton with a Pion Field in the Global Color Symmetry Model
We calculate the property of the global color symmetry model soliton with the
pion field being included explicitly. The calculated results indicate that the
pion field provides a strong attraction so that the eigen-energy of a quark and
the mass of a soliton reduce drastically, in contrast to those with only the
sigma field.Comment: 15 pages, 2 figure
Deep Discrete Hashing with Self-supervised Pairwise Labels
Hashing methods have been widely used for applications of large-scale image
retrieval and classification. Non-deep hashing methods using handcrafted
features have been significantly outperformed by deep hashing methods due to
their better feature representation and end-to-end learning framework. However,
the most striking successes in deep hashing have mostly involved discriminative
models, which require labels. In this paper, we propose a novel unsupervised
deep hashing method, named Deep Discrete Hashing (DDH), for large-scale image
retrieval and classification. In the proposed framework, we address two main
problems: 1) how to directly learn discrete binary codes? 2) how to equip the
binary representation with the ability of accurate image retrieval and
classification in an unsupervised way? We resolve these problems by introducing
an intermediate variable and a loss function steering the learning process,
which is based on the neighborhood structure in the original space.
Experimental results on standard datasets (CIFAR-10, NUS-WIDE, and Oxford-17)
demonstrate that our DDH significantly outperforms existing hashing methods by
large margin in terms of~mAP for image retrieval and object recognition. Code
is available at \url{https://github.com/htconquer/ddh}
Microstrip superconducting quantum interference device amplifiers with submicron Josephson junctions: enhanced gain at gigahertz frequencies
We present measurements of an amplifier based on a dc superconducting quantum
interference device (SQUID) with submicron Al-AlOx-Al Josephson junctions. The
small junction size reduces their self-capacitance and allows for the use of
relatively large resistive shunts while maintaining nonhysteretic operation.
This leads to an enhancement of the SQUID transfer function compared to SQUIDs
with micron-scale junctions. The device layout is modified from that of a
conventional SQUID to allow for coupling signals into the amplifier with a
substantial mutual inductance for a relatively short microstrip coil.
Measurements at 310 mK exhibit gain of 32 dB at 1.55 GHz.Comment: Version with high resolution figures at:
http://physics.syr.edu/~bplourde/bltp-publications.ht
Episodic transport of discrete magma batches beneath Aso volcano
Magma ascent, storage, and discharge in the trans-crustal magmatic system are keys to long-term volcanic output and short-term eruption dynamics. How a distinct magma batch transports from a deep reservoir(s) to a pre-eruptive storage pool with eruptible magma remains elusive. Here we show that repetitive very-long-period signals (VLPs) beneath the Aso volcano are preceded by a short-lived (~50–100 s), synchronous deformation event ~3 km apart from the VLP source. Source mechanism of a major volumetric component (~50–440 m3 per event) and a minor low-angle normal-fault component, together with petrological evidence, suggests episodic transport of discrete magma batches from an over-pressured chamber roof to a pre-eruptive storage pool near the brittle-ductile transition regime. Magma ascent velocity, decompression rate, and cumulative magma output deduced from recurrent deformation events before recent 2014 and 2016 eruptions reconcile retrospective observations of the eruption style, tephra fallouts, and plume heights, promising real-time evaluation of upcoming eruptions
Reducing microwave loss in superconducting resonators due to trapped vortices
Microwave resonators with high quality factors have enabled many recent
breakthroughs with superconducting qubits and photon detectors, typically
operated in shielded environments to reduce the ambient magnetic field.
Insufficient shielding or pulsed control fields can introduce vortices, leading
to reduced quality factors, although increased pinning can mitigate this
effect. A narrow slot etched into the resonator surface provides a
straightforward method for pinning enhancement without otherwise affecting the
resonator. Resonators patterned with such a slot exhibited over an order of
magnitude reduction in the excess loss due to vortices compared with identical
resonators from the same film with no slot
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