10,901 research outputs found
Evaluating Agricultural Banking Efficiency Using the Fourier Flexible Functional Form
This study applied more flexible cost functional form, Fourier Flexible Functional Form, and tested the validity of the Translog cost functional form as to estimate the cost function incorporating risk and loan's quality for banking industry. Meanwhile, the study extended four different cost efficiency measures for banking industry not only among different sized banks but also between commercial banks and agricultural banks. And thereafter, by evaluating these efficiency measures, banks will identify sources of inefficiency, which should aid banks in developing approaches to improve their operational policies, procedures, and performance.Agricultural Finance,
DISCRETE AND CONTINUOUS TIME MODELS FOR FARM CREDIT MIGRATION ANALYSIS
This paper introduces two continuous time models, i.e. time homogenous and non-homogenous Markov chain models, for analyzing farm credit migration as alternatives to the traditional discrete time model cohort method. Results illustrate that the two continuous time models provide more detailed, accurate and reliable estimates of farm credit migration rates than the discrete time model. Metric comparisons among the three transition matrices show that the imposition of the potentially unrealistic assumption of time homogeneity still produces more accurate estimates of farm credit migration rates, although the equally reliable figures under the non-homogenous time model seem more plausible given the greater relevance and applicability of the latter model to farm business conditions.Agricultural Finance,
Redshifts and Luminosities for 112 Gamma Ray Bursts
Two different luminosity indicators have recently been proposed for Gamma Ray
Bursts that use gamma-ray observations alone. They relate the burst luminosity
(L) with the time lag between peaks in hard and soft energies, and the
spikiness or variability of the burst's light curve (V). These relations are
currently justified and calibrated with only 6 or 7 bursts with known red
shifts. We have examined BATSE data for the lag and V for 112 bursts. (1) A
strong correlation between the lag and V exists, and it is exactly as predicted
from the two proposed relations. This is proof that both luminosity indicators
are reliable. (2) GRB830801 is the all-time brightest burst, yet with a small V
and a large lag, and hence is likely the closest known event being perhaps as
close as 3.2 Mpc. (3) We have combined the luminosities as derived from both
indicators as a means to improve the statistical and systematic accuracy when
compared with the accuracy from either method alone. The result is a list of
112 bursts with good luminosities and hence red shifts. (4) The burst averaged
hardness ratio rises strongly with the luminosity of the burst. (5) The burst
luminosity function is a broken power law, with the break at L = 2x10^{52}
erg/s. The luminosity function has power law indices of -2.8+-0.2 above the
break and -1.7+-0.1 below the break. (6) The number density of GRBs varies with
red shift roughly as (1+z)^(2.5+-0.3) between 0.2<z<5. Excitingly, this result
also provides a measure of the star formation rate out to z~5 with no effects
from reddening, and the rate is rising uniformly for red shifts above 2.Comment: 13 pages, 4 figures, submitted to ApJLet
Parity independence of the zero-bias conductance peak in a nanowire based topological superconductor-quantum dot hybrid device
We explore the signatures of Majorana fermions in a nanowire based
topological superconductor-quantum dot-topological superconductor hybrid device
by charge transport measurements. The device is made from an epitaxially grown
InSb nanowire with two superconductor Nb contacts on a Si/SiO substrate. At
low temperatures, a quantum dot is formed in the segment of the InSb nanowire
between the two Nb contacts and the two Nb contacted segments of the InSb
nanowire show superconductivity due to the proximity effect. At zero magnetic
field, well defined Coulomb diamonds and the Kondo effect are observed in the
charge stability diagram measurements in the Coulomb blockade regime of the
quantum dot. Under the application of a finite, sufficiently strong magnetic
field, a zero-bias conductance peak structure is observed in the same Coulomb
blockade regime. It is found that the zero-bias conductance peak is present in
many consecutive Coulomb diamonds, irrespective of the even-odd parity of the
quasi-particle occupation number in the quantum dot. In addition, we find that
the zero-bias conductance peak is in most cases accompanied by two differential
conductance peaks, forming a triple-peak structure, and the separation between
the two side peaks in bias voltage shows oscillations closely correlated to the
background Coulomb conductance oscillations of the device. The observed
zero-bias conductance peak and the associated triple-peak structure are in line
with the signatures of Majorana fermion physics in a nanowire based topological
superconductor-quantum dot-topological superconductor system, in which the two
Majorana bound states adjacent to the quantum dot are hybridized into a pair of
quasi-particle states with finite energies and the other two Majorana bound
states remain as the zero-energy modes located at the two ends of the entire
InSb nanowire.Comment: 6 pages, 4 figure
Formation of Long Single Quantum Dots in High Quality InSb Nanowires Grown by Molecular Beam Epitaxy
We report on realization and transport spectroscopy study of single quantum
dots (QDs) made from InSb nanowires grown by molecular beam epitaxy (MBE). The
nanowires employed are 50-80 nm in diameter and the QDs are defined in the
nanowires between the source and drain contacts on a Si/SiO substrate. We
show that highly tunable QD devices can be realized with the MBE-grown InSb
nanowires and the gate-to-dot capacitance extracted in the many-electron
regimes is scaled linearly with the longitudinal dot size, demonstrating that
the devices are of single InSb nanowire QDs even with a longitudinal size of
~700 nm. In the few-electron regime, the quantum levels in the QDs are resolved
and the Land\'e g-factors extracted for the quantum levels from the
magnetotransport measurements are found to be strongly level-dependent and
fluctuated in a range of 18-48. A spin-orbit coupling strength is extracted
from the magnetic field evolutions of a ground state and its neighboring
excited state in an InSb nanowire QD and is on the order of ~300 eV. Our
results establish that the MBE-grown InSb nanowires are of high crystal quality
and are promising for the use in constructing novel quantum devices, such as
entangled spin qubits, one-dimensional Wigner crystals and topological quantum
computing devices.Comment: 19 pages, 5 figure
Efficient symmetric multiparty quantum state sharing of an arbitrary m-qubit state
We present a scheme for symmetric multiparty quantum state sharing of an
arbitrary -qubit state with Greenberger-Horne-Zeilinger states following
some ideas from the controlled teleportation [Phys. Rev. A \textbf{72}, 02338
(2005)]. The sender Alice performs Bell-state measurements on her
particles and the controllers need only to take some single-photon product
measurements on their photons independently, not Bell-state measurements, which
makes this scheme more convenient than the latter. Also it does not require the
parties to perform a controlled-NOT gate on the photons for reconstructing the
unknown -qubit state and it is an optimal one as its efficiency for qubits
approaches the maximal value.Comment: 6 pages, no figures; It simplifies the process for sharing an
arbitrary m-qubit state in Phys. Rev. A 72, 022338 (2005) (quant-ph/0501129
Broad-lined type Ic supernova iPTF16asu: A challenge to all popular models
It is well-known that ordinary supernovae (SNe) are powered by 56Ni cascade
decay. Broad-lined type Ic SNe (SNe Ic-BL) are a subclass of SNe that are not
all exclusively powered by 56Ni decay. It was suggested that some SNe Ic-BL are
powered by magnetar spin-down. iPTF16asu is a peculiar broad-lined type Ic
supernova discovered by the intermediate Palomar Transient Factory. With a
rest-frame rise time of only 4 days, iPTF16asu challenges the existing popular
models, for example, the radioactive heating (56Ni-only) and the magnetar+56Ni
models. Here we show that this rapid rise could be attributed to interaction
between the SN ejecta and a pre-existing circumstellar medium ejected by the
progenitor during its final stages of evolution, while the late-time light
curve can be better explained by energy input from a rapidly spinning magnetar.
This model is a natural extension to the previous magnetar model. The mass-loss
rate of the progenitor and ejecta mass are consistent with a progenitor that
experienced a common envelope evolution in a binary. An alternative model for
the early rapid rise of the light curve is the cooling of a shock propagating
into an extended envelope of the progenitor. It is difficult at this stage to
tell which model (interaction+magnetar+56Ni or cooling+magnetar+56Ni) is better
for iPTF16asu. However, it is worth noting that the inferred envelope mass in
the cooling+magnetar+56Ni is very high.Comment: 11 pages, 4 figures, 3 table
Circular quantum secret sharing
A circular quantum secret sharing protocol is proposed, which is useful and
efficient when one of the parties of secret sharing is remote to the others who
are in adjacent, especially the parties are more than three. We describe the
process of this protocol and discuss its security when the quantum information
carrying is polarized single photons running circularly. It will be shown that
entanglement is not necessary for quantum secret sharing. Moreover, the
theoretic efficiency is improved to approach 100% as almost all the instances
can be used for generating the private key, and each photon can carry one bit
of information without quantum storage. It is straightforwardly to utilize this
topological structure to complete quantum secret sharing with multi-level
two-particle entanglement in high capacity securely.Comment: 7 pages, 2 figure
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