2,194 research outputs found
Anomalous single-mode lasing induced by nonlinearity and the non-Hermitian skin effect
Single-mode operation is a desirable but elusive property for lasers
operating at high pump powers. Typically, single-mode lasing is attainable
close to threshold, but increasing the pump power gives rise to multiple lasing
peaks due to inter-modal gain competition. We propose a laser with the opposite
behavior: multi-mode lasing occurs at low output powers, but pumping beyond a
certain value produces a single lasing mode, with all other candidate modes
experiencing negative effective gain. This behavior arises in a lattice of
coupled optical resonators with non-fine-tuned asymmetric couplings, and is
caused by an interaction between nonlinear gain saturation and the
non-Hermitian skin effect. The single-mode lasing is observed in both frequency
domain and time domain simulations. It is robust against on-site disorder, and
scales up to large lattice sizes. This finding might be useful for implementing
high-power laser arrays
In-Line-Test of Variability and Bit-Error-Rate of HfOx-Based Resistive Memory
Spatial and temporal variability of HfOx-based resistive random access memory
(RRAM) are investigated for manufacturing and product designs. Manufacturing
variability is characterized at different levels including lots, wafers, and
chips. Bit-error-rate (BER) is proposed as a holistic parameter for the write
cycle resistance statistics. Using the electrical in-line-test cycle data, a
method is developed to derive BERs as functions of the design margin, to
provide guidance for technology evaluation and product design. The proposed BER
calculation can also be used in the off-line bench test and build-in-self-test
(BIST) for adaptive error correction and for the other types of random access
memories.Comment: 4 pages. Memory Workshop (IMW), 2015 IEEE Internationa
The Role of Federated Learning in a Wireless World with Foundation Models
Foundation models (FMs) are general-purpose artificial intelligence (AI)
models that have recently enabled multiple brand-new generative AI
applications. The rapid advances in FMs serve as an important contextual
backdrop for the vision of next-generation wireless networks, where federated
learning (FL) is a key enabler of distributed network intelligence. Currently,
the exploration of the interplay between FMs and FL is still in its nascent
stage. Naturally, FMs are capable of boosting the performance of FL, and FL
could also leverage decentralized data and computing resources to assist in the
training of FMs. However, the exceptionally high requirements that FMs have for
computing resources, storage, and communication overhead would pose critical
challenges to FL-enabled wireless networks. In this article, we explore the
extent to which FMs are suitable for FL over wireless networks, including a
broad overview of research challenges and opportunities. In particular, we
discuss multiple new paradigms for realizing future intelligent networks that
integrate FMs and FL. We also consolidate several broad research directions
associated with these paradigms.Comment: 8 pages, 5 figures, 1 tabl
The rise of the cosmetic industry in ancient China: insights from a 2,700‐year‐old face cream
Cosmetic has a long history in China while its origin has remained unclear. It potentially originated in the Spring and Autumn period (770‐476 BC) but little is known about its early manufacture and use. The Liujiawa Site, located at the southern edge of the Loess Plateau in northern China, was the late capital of the Rui State in the early to middle Spring and Autumn Period. During the excavation, a sealed small and exquisite container with suspected cosmetic use was unearthed from tomb M49 belonging to a male associated with the aristocratic class. Here, we report the multidisciplinary application of ATR‐FTIR, XRD, SEM, stable isotope analysis, GC/MS, and GC‐C‐IRMS analysis of the residue inside the container, demonstrating that the residue, made of ruminant adipose fat mixed with monohydrocalcite coming from cave moonmilk, was likely used as cosmetic face cream by the nobleman of ancient Rui State. This work provides an early example of cosmetic production in China and, together with the prevalence of similar cosmetic containers during this period, suggests the rise of an incipient cosmetics industry. Furthermore, the exploitation of moonmilk, a special stalactite in some limestone caves, reflects the link between early Taoist School and cosmetic production encouraged by the aristocratic class.1. Introduction 2. Materials and Methods 2.1 Site and sample background 2.2 FTIR analysis 2.3 XRD analysis 2.4 SEM analysis 2.5 Inorganic carbon and oxygen isotope analysis 2.6 GC/MS analysis 2.7 GC-C-IRMS analysis 3. Results 3.1 The source of inorganic mineral 3.2 The origin of fat matrix 4. Discussion 4.1 The origin of the animal lipids 4.2 The exploitation of stalactites along with the Taoist School Cave Cultus 4.3 The earliest face cream in China 4.4 The rise of the cosmetic industry in the early period of Spring and Autum
f(R) Theories of Supergravities and Pseudo-supergravities
We present f(R) theories of ten-dimensional supergravities, including the
fermionic sector up to the quadratic order in fermion fields. They are obtained
by performing the conformal scaling on the usual supergravities to the f(R)
frame in which the dilaton becomes an auxiliary field and can be integrated
out. The f(R) frame coincides with that of M-theory, D2-branes or NS-NS
5-branes. We study various BPS p-brane solutions and their near-horizon AdS
\times sphere geometries in the context of the f(R) theories. We find that new
solutions emerge with global structures that do not exist in the corresponding
solutions of the original supergravity description. In lower dimensions, We
construct the f(R) theory of N=2, D=5 gauged supergravity with a vector
multiplet, and that for the four-dimensional U(1)^4 gauged theory with three
vector fields set equal. We find that some previously-known BPS singular
"superstars" become wormholes in the f(R) theories. We also construct a large
class of f(R) (gauged) pseudo-supergravities. In addition we show that the
breathing mode in the Kaluza-Klein reduction of Gauss-Bonnet gravity on S^1 is
an auxiliary field and can be integrated out.Comment: Latex, 46 page
Degenerate Rotating Black Holes, Chiral CFTs and Fermi Surfaces I - Analytic Results for Quasinormal Modes
In this work we discuss charged rotating black holes in
that degenerate to extremal black holes with zero entropy. These black holes
have scaling properties between charge and angular momentum similar to those of
Fermi surface operators in a subsector of SYM. We add a
massless uncharged scalar to the five dimensional supergravity theory, such
that it still forms a consistent truncation of the type IIB ten dimensional
supergravity and analyze its quasinormal modes. Separating the equation of
motion to a radial and angular part, we proceed to solve the radial equation
using the asymptotic matching expansion method applied to a Heun equation with
two nearby singularities. We use the continued fraction method for the angular
Heun equation and obtain numerical results for the quasinormal modes. In the
case of the supersymmetric black hole we present some analytic results for the
decay rates of the scalar perturbations. The spectrum of quasinormal modes
obtained is similar to that of a chiral 1+1 CFT, which is consistent with the
conjectured field-theoretic dual. In addition, some of the modes can be found
analytically.Comment: 41 pages, 1 figure, LaTeX; v2: typos corrected, references adde
Top Quark Decays into Heavy Quark Mesons
For top quark decays into heavy quark mesons and , a
complete calculation to the leading order both in QCD coupling constant
and in , the typical velocity of the heavy quarks inside the
mesons, is performed. Relatons between the top quark mass and the decay
branching ratios are studied. Comparion with the results which are obtained by
using the quark frangmentation functions is also discussed. The branching
ratios are consistent (within a factor of ) with that obtained using
fragmentation functions at GeV.Comment: 15 pages in LaTex form, 4 figures include
Ectrodactyly and lethal pulmonary acinar dysplasia associated with homozygous FGFR2 mutations identified by exome sequencing
First published: 11 July 2016Abstract not availableChristopher P. Barnett, Nathalie J. Nataren, Manuela Klingler-Hoffmann, Quenten Schwarz, Chan-Eng Chong, Young K. Lee, Damien L. Bruno, Jill Lipsett, Andrew J. McPhee, Andreas W. Schreiber, Jinghua Feng, Christopher N. Hahn, and Hamish S. Scot
Large energy mode locking of an erbium-doped fiber laser with atomic layer graphene
We report on large energy pulse generation in an erbium-doped fiber laser
passively mode-locked with atomic layer graphene. Stable mode locked pulses
with single pulse energy up to 7.3 nJ and pulse width of 415 fs have been
directly generated from the laser. Our results show that atomic layer graphene
could be a promising saturable absorber for large energy mode locking.Comment: 14 pages 4 figure
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