20,598 research outputs found
The profitability and risk effects of allowing bank holding companies to merge with other financial firms: a simulation study
Bank mergers ; Bank holding companies ; Nonbank activities
Investigating the banking consolidation trend
This paper examines whether the U.S. banking industry's recent consolidation trend--toward fewer and bigger firms--is a natural result of market forces. The paper finds that it is not: The evidence does not support the popular claims that large banking firms are more efficient and less risky than smaller firms or the notion that the industry is consolidating in order to eliminate excess capacity. The paper suggests, instead, that public policies are encouraging banks to merge, although it acknowledges that other forces may be at work as well.Bank mergers
A simple method for estimation of coagulation efficiency in mixed aerosols
Aerosols of KBr and AgNO3 were mixed, exposed to light in a glass tube and collected in the dark. About 15% of the collected material was reduced to silver upon development. Thus, two aerosols of particles that react to form a photo-reducible compound can be used to measure coagulation efficiency
Template epitaxial growth of thermoelectric Bi/BiSb superlattice nanowires by charge-controlled pulse electrodeposition
© The Electrochemical Society, Inc. 2009. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in The Journal of The Electrochemical Society, 156(9), 2009.Bi/BiSb superlattice nanowires (SLNWs) with a controllable and very small bilayer thickness and a sharp segment interface were grown by adopting a charge-controlled pulse electrodeposition. The deposition parameters were optimized to ensure an epitaxial growth of the SLNWs with a preferential orientation. The segment length and bilayer thickness of the SLNWs can be controlled simply by changing the modulating time, and the consistency of the segment length can be well maintained by our approach. The Bravais law in the electrodeposited nanowires is verified by the SLNW structure. The current–voltage measurement shows that the SLNWs have good electrical conductance, particularly those with a smaller bilayer thickness. The Bi/BiSb SLNWs might have excellent thermoelectric performances.National Natural Science Foundation
of China and the National
Major Project of Fundamental Research for Nanomaterials and
Nanostructures
Mixed perturbative expansion: the validity of a model for the cascading
A new type of perturbative expansion is built in order to give a rigorous
derivation and to clarify the range of validity of some commonly used model
equations.
This model describes the evolution of the modulation of two short and
localized pulses, fundamental and second harmonic, propagating together in a
bulk uniaxial crystal with non-vanishing second order susceptibility
and interacting through the nonlinear effect known as ``cascading'' in
nonlinear optics.
The perturbative method mixes a multi-scale expansion with a power series
expansion of the susceptibility, and must be carefully adapted to the physical
situation. It allows the determination of the physical conditions under which
the model is valid: the order of magnitude of the walk-off, phase-mismatch,and
anisotropy must have determined values.Comment: arxiv version is already officia
Efficient Optimal Minimum Error Discrimination of Symmetric Quantum States
This paper deals with the quantum optimal discrimination among mixed quantum
states enjoying geometrical uniform symmetry with respect to a reference
density operator . It is well-known that the minimal error probability
is given by the positive operator-valued measure (POVM) obtained as a solution
of a convex optimization problem, namely a set of operators satisfying
geometrical symmetry, with respect to a reference operator , and
maximizing . In this paper, by resolving the dual
problem, we show that the same result is obtained by minimizing the trace of a
semidefinite positive operator commuting with the symmetry operator and
such that . The new formulation gives a deeper insight into the
optimization problem and allows to obtain closed-form analytical solutions, as
shown by a simple but not trivial explanatory example. Besides the theoretical
interest, the result leads to semidefinite programming solutions of reduced
complexity, allowing to extend the numerical performance evaluation to quantum
communication systems modeled in Hilbert spaces of large dimension.Comment: 5 pages, 1 Table, no figure
Optically mediated nonlinear quantum optomechanics
We consider theoretically the optomechanical interaction of several
mechanical modes with a single quantized cavity field mode for linear and
quadratic coupling. We focus specifically on situations where the optical
dissipation is the dominant source of damping, in which case the optical field
can be adiabatically eliminated, resulting in effective multimode interactions
between the mechanical modes. In the case of linear coupling, the coherent
contribution to the interaction can be exploited e.g. in quantum state swapping
protocols, while the incoherent part leads to significant modifications of cold
damping or amplification from the single-mode situation. Quadratic coupling can
result in a wealth of possible effective interactions including the analogs of
second-harmonic generation and four-wave mixing in nonlinear optics, with
specific forms depending sensitively on the sign of the coupling. The
cavity-mediated mechanical interaction of two modes is investigated in two
limiting cases, the resolved sideband and the Doppler regime. As an
illustrative application of the formal analysis we discuss in some detail a
two-mode system where a Bose-Einstein condensate is optomechanically linearly
coupled to the moving end mirror of a Fabry-P\'erot cavity.Comment: 11 pages, 8 figure
Big Bang Nucleosynthesis with Long Lived Charged Massive Particles
We consider Big Bang Nucleosynthesis (BBN) with long lived charged massive
particles. Before decaying, the long lived charged particle recombines with a
light element to form a bound state like a hydrogen atom. This effect modifies
the nuclear reaction rates during the BBN epoch through the modifications of
the Coulomb field and the kinematics of the captured light elements, which can
change the light element abundances. It is possible that the heavier nuclei
abundances such as Li and Be decrease sizably, while the ratios ,
D/H, and He/H remain unchanged. This may solve the current discrepancy
between the BBN prediction and the observed abundance of Li. If future
collider experiments found signals of a long-lived charged particle inside the
detector, the information of its lifetime and decay properties could provide
insights to understand not only the particle physics models but also the
phenomena in the early universe in turn.Comment: 20 pages, 6 figures, published version in Physical Review
Limits of Nematoscelis megalops in the northwestern Atlantic in relation to Gulf Stream cold core rings. II, Physiological and biochemical effects of expatriation
Originally published in the Journal of Marine Research, v. 36, 1, 1978, pp. 143-159Nematoscelis megalops, a cold water euphausiid commonly found in Northwestern Atlantic
Slope Water, is frequently transported in the cores of Gulf Stream cyclonic rings into the Sargasso
Sea. The inner core made of cold Slope Water gradually assumes physical and biological
characteristics of the surrounding Sargasso Sea. These changes gradually lead to a localized
extinction of this species in the core of the ring. Samples of N. megalops taken from the same
ring at 6 and 9 months after its formation show a weakened physiological and biochemical
condition.
Deterioration of ring individuals is evidenced by an increase in body water content and a
reduction in total body lipid, carbon, respiration rates, and nitrogen relative to Slope Water
individuals. By 6 months it appears that ring N. megalops must supplement food intake by
metabolizing some of their body protein and by 9 months they appear to use lipids as well.
A shipboard starvation experiment involving 40 Slope Water individuals showed that physiological
and biochemical states similar to those found in individuals from the 9 months old ring
could be duplicated in 4 days of complete starvation.Prepared for the Office of Naval Research under
Contracts N00014-66-C-0241; NR 083-004 and
N00014-?4-C-0262; NR 083-004 and for the National
Science Foundation under Grant DES ?4-02?83 A01
A 163 micron laser heterodyne radiometer for OH
A 163 micron (1.836 THz) radiometer developed for airplane and/or balloon platforms is described. The laser local oscillator is a CO2 pumped methanol laser operating at a frequency which is approx. 1 GHz from the J = 3/2 - 1/2 transition of OH. The laser is used directly as a local oscillator or is translated in frequency to closer coincidence with the OH emission, depending on achieved detector IF bandwidth. Frequency translation techniques which are described are diode mixing and a method of single sideband generation using an external Stark modulated gas cell. The photoconductive mixer used is a strained Ge crystal, doped with Ga, originally used as an incoherent detector. The uniaxial strain on the Ga doped Ge crystal shifts the threshold for photoconduction from 100/cm to frequencies as low as 50/cm. These detectors are currently being characterized as mixers in the laboratory. Of particular interest are the effect of local oscillator power and strain on IF, bandwidth detector impedance, and conversion loss. Preliminary results of these tests are described and compared with theorectical expectations
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