1,013 research outputs found
The Child is Father of the Man: Foresee the Success at the Early Stage
Understanding the dynamic mechanisms that drive the high-impact scientific
work (e.g., research papers, patents) is a long-debated research topic and has
many important implications, ranging from personal career development and
recruitment search, to the jurisdiction of research resources. Recent advances
in characterizing and modeling scientific success have made it possible to
forecast the long-term impact of scientific work, where data mining techniques,
supervised learning in particular, play an essential role. Despite much
progress, several key algorithmic challenges in relation to predicting
long-term scientific impact have largely remained open. In this paper, we
propose a joint predictive model to forecast the long-term scientific impact at
the early stage, which simultaneously addresses a number of these open
challenges, including the scholarly feature design, the non-linearity, the
domain-heterogeneity and dynamics. In particular, we formulate it as a
regularized optimization problem and propose effective and scalable algorithms
to solve it. We perform extensive empirical evaluations on large, real
scholarly data sets to validate the effectiveness and the efficiency of our
method.Comment: Correct some typos in our KDD pape
Electronic structure and electric-field gradients analysis in
Electric field gradients (EFG's) were calculated for the compound at
both and sites. The calculations were performed within
the density functional theory (DFT) using the augmented plane waves plus local
orbital (APW+lo) method employing the so-called LDA+U scheme. The
compound were treated as nonmagnetic, ferromagnetic, and antiferromagnetic
cases. Our result shows that the calculated EFG's are dominated at the
site by the Ce-4f states. An approximately linear relation is
intuited between the main component of the EFG's and total density of states
(DOS) at Fermi level. The EFG's from our LDA+U calculations are in better
agreement with experiment than previous EFG results, where appropriate
correlations had not been taken into account among 4f-electrons. Our result
indicates that correlations among 4f-electrons play an important role in this
compound and must be taken into account
Slope gradient and shape effects on soil profiles in the Northern mountainous forests of Iran
Hybrid dispersion laser scanner.
Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points
Mid-infrared optical parametric amplifier using silicon nanophotonic waveguides
All-optical signal processing is envisioned as an approach to dramatically
decrease power consumption and speed up performance of next-generation optical
telecommunications networks. Nonlinear optical effects, such as four-wave
mixing (FWM) and parametric gain, have long been explored to realize
all-optical functions in glass fibers. An alternative approach is to employ
nanoscale engineering of silicon waveguides to enhance the optical
nonlinearities by up to five orders of magnitude, enabling integrated
chip-scale all-optical signal processing. Previously, strong two-photon
absorption (TPA) of the telecom-band pump has been a fundamental and
unavoidable obstacle, limiting parametric gain to values on the order of a few
dB. Here we demonstrate a silicon nanophotonic optical parametric amplifier
exhibiting gain as large as 25.4 dB, by operating the pump in the mid-IR near
one-half the band-gap energy (E~0.55eV, lambda~2200nm), at which parasitic
TPA-related absorption vanishes. This gain is high enough to compensate all
insertion losses, resulting in 13 dB net off-chip amplification. Furthermore,
dispersion engineering dramatically increases the gain bandwidth to more than
220 nm, all realized using an ultra-compact 4 mm silicon chip. Beyond its
significant relevance to all-optical signal processing, the broadband
parametric gain also facilitates the simultaneous generation of multiple
on-chip mid-IR sources through cascaded FWM, covering a 500 nm spectral range.
Together, these results provide a foundation for the construction of
silicon-based room-temperature mid-IR light sources including tunable
chip-scale parametric oscillators, optical frequency combs, and supercontinuum
generators
Bridging the Mid-Infrared-to-Telecom Gap with Silicon Nanophotonic Spectral Translation
Expanding far beyond traditional applications in optical interconnects at
telecommunications wavelengths, the silicon nanophotonic integrated circuit
platform has recently proven its merits for working with mid-infrared (mid-IR)
optical signals in the 2-8 {\mu}m range. Mid-IR integrated optical systems are
capable of addressing applications including industrial process and
environmental monitoring, threat detection, medical diagnostics, and free-space
communication. Rapid progress has led to the demonstration of various silicon
components designed for the on-chip processing of mid-IR signals, including
waveguides, vertical grating couplers, microcavities, and electrooptic
modulators. Even so, a notable obstacle to the continued advancement of
chip-scale systems is imposed by the narrow-bandgap semiconductors, such as
InSb and HgCdTe, traditionally used to convert mid-IR photons to electrical
currents. The cryogenic or multi-stage thermo-electric cooling required to
suppress dark current noise, exponentially dependent upon the ratio Eg/kT, can
limit the development of small, low-power, and low-cost integrated optical
systems for the mid-IR. However, if the mid-IR optical signal could be
spectrally translated to shorter wavelengths, for example within the
near-infrared telecom band, photodetectors using wider bandgap semiconductors
such as InGaAs or Ge could be used to eliminate prohibitive cooling
requirements. Moreover, telecom band detectors typically perform with higher
detectivity and faster response times when compared with their mid-IR
counterparts. Here we address these challenges with a silicon-integrated
approach to spectral translation, by employing efficient four-wave mixing (FWM)
and large optical parametric gain in silicon nanophotonic wires
Evanescent light-matter Interactions in Atomic Cladding Wave Guides
Alkali vapors, and in particular rubidium, are being used extensively in
several important fields of research such as slow and stored light non-linear
optics3 and quantum computation. Additionally, the technology of alkali vapors
plays a major role in realizing myriad industrial applications including for
example atomic clocks magentometers8 and optical frequency stabilization.
Lately, there is a growing effort towards miniaturizing traditional
centimeter-size alkali vapor cells. Owing to the significant reduction in
device dimensions, light matter interactions are greatly enhanced, enabling new
functionalities due to the low power threshold needed for non-linear
interactions. Here, taking advantage of the mature Complimentary
Metal-Oxide-Semiconductor (CMOS) compatible platform of silicon photonics, we
construct an efficient and flexible platform for tailored light vapor
interactions on a chip. Specifically, we demonstrate light matter interactions
in an atomic cladding wave guide (ACWG), consisting of CMOS compatible silicon
nitride nano wave-guide core with a Rubidium (Rb) vapor cladding. We observe
the highly efficient interaction of the electromagnetic guided mode with the
thermal Rb cladding. The nature of such interactions is explained by a model
which predicts the transmission spectrum of the system taking into account
Doppler and transit time broadening. We show, that due to the high confinement
of the optical mode (with a mode area of 0.3{\lambda}2), the Rb absorption
saturates at powers in the nW regime.Comment: 10 Pages 4 Figures. 1 Supplementar
Distributed user selection scheme for uplink multiuser MIMO systems in a multicell environment
Diagnosis and management of complications from the treatment of primary central nervous system tumors in adults
Central nervous system (CNS) tumor patients commonly undergo multimodality treatment in the course of their disease. Adverse effects and complications from these interventions have not been systematically studied, but pose significant challenges in clinical practice and impact function and quality of life, especially in the management of long-term brain tumor survivors. Here, the European Association of Neuro-Oncology (EANO) has developed recommendations to prevent, diagnose, and manage adverse effects and complications in the adult primary brain CNS tumor (except lymphomas) patient population with a specific focus on surgery, radiotherapy, and pharmacotherapy. Specifically, we also provide recommendations for dose adaptations, interruptions, and reexposure for pharmacotherapy that may serve as a reference for the management of standard of care in clinical trials. We also summarize which interventions are unnecessary, inactive or contraindicated. This consensus paper should serve as a reference for the conduct of standard therapy within and outside of clinical trials
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