2,461 research outputs found
Multi-dimensional band structure spectroscopy in the synthetic frequency dimension
The concept of synthetic dimensions in photonics provides a versatile
platform in exploring multi-dimensional physics. Many of these physics are
characterized by band structures in more than one dimensions. Existing efforts
on band structure measurements in the photonic synthetic frequency dimension
however are limited to either one-dimensional Brillouin zones or
one-dimensional subsets of multi-dimensional Brillouin zones. Here we
theoretically propose and experimentally demonstrate a method to fully measure
multi-dimensional band structures in the synthetic frequency dimension. We use
a single photonic resonator under dynamical modulation to create a
multi-dimensional synthetic frequency lattice. We show that the band structure
of such a lattice over the entire multi-dimensional Brillouin zone can be
measured by introducing a gauge potential into the lattice Hamiltonian. Using
this method, we perform experimental measurements of two-dimensional band
structures of a Hermitian and a non-Hermitian Hamiltonian. The measurements
reveal some of the general properties of point-gap topology of the
non-Hermitian Hamiltonian in more than one dimensions. Our results demonstrate
experimental capabilities to fully characterize high-dimensional physical
phenomena in the photonic synthetic frequency dimension
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IV. H Time Lags and Implications for Super-Eddington Accretion
We have completed two years of photometric and spectroscopic monitoring of a
large number of active galactic nuclei (AGNs) with very high accretion rates.
In this paper, we report on the result of the second phase of the campaign,
during 2013--2014, and the measurements of five new H time lags out of
eight monitored AGNs. All five objects were identified as super-Eddington
accreting massive black holes (SEAMBHs). The highest measured accretion rates
for the objects in this campaign are , where
,
is the mass accretion rates, is the Eddington luminosity and
is the speed of light. We find that the H time lags in SEAMBHs are
significantly shorter than those measured in sub-Eddington AGNs, and the
deviations increase with increasing accretion rates. Thus, the relationship
between broad-line region size () and optical luminosity at
5100\AA, , requires accretion rate as an additional
parameter. We propose that much of the effect may be due to the strong
anisotropy of the emitted slim-disk radiation. Scaling by
the gravitational radius of the black hole, we define a new radius-mass
parameter () and show that it saturates at a critical accretion rate of
, indicating a transition from thin to slim
accretion disk and a saturated luminosity of the slim disks. The parameter
is a very useful probe for understanding the various types of accretion onto
massive black holes. We briefly comment on implications to the general
population of super-Eddington AGNs in the universe and applications to
cosmology.Comment: 53 pages, 12 figures, 7 tables, accepted for publication in The
Astrophysical Journa
Influence of macroeconomics factors and legal stability to the insurance growth in the ASEAN-5 countries
This paper examines the influence of legal stability and macroeconomics factor to the non-life insurance development. In light of the growing significance of foreign direct investment (FDI) and trade that stimulate insurance sector, and the stress placed on legal stability of the countries, investigating the role of legal stability is crucial to sustain a country’s financial development. This study employs a panel data analysis spanning 20 years in the selected developing countries. The findings suggest that higher trade, higher income, higher stock market trading activities and higher availability of finance credit will enhance the non-life insurance development. Legal stability such as enhancement on the property right and government integrity will improve the non-life insurance development. When the legal environments in emerging countries are more stable, the FDI and stocks market will become more encouraging and stimulate non-life insurance development. The policy makers should improve the legal stability in emerging countries to improve the financial development for minimizing the gap with developed countries. This study includes the institutional factors components in addition to the macroeconomics factors could provide a complete picture towards the improvement of non-life insurance development in emerging and transition countries
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