56,218 research outputs found
Diversification, Organization, and Efficiency: Evidence from Bank Holding Companies
We use a portfolio-simulation technique to estimate the value added from diversification by bank holding companies. Using a sample of 412 multi-bank bank holding companies (MBHCs) from 1990 to 1994, we construct pro forma benchmark portfolios for each MBHC composed of shares of single banks, weighted to correspond to the MBHC's distribution of activities. We then compare the performance and characteristics of the MBHCs to that of their pro forma benchmarks. Diversification through the holding company structure does appear to bring certain benefits: the MBHCs hold less capital and engage in more lending, on average, then their pro forma benchmarks. However, these desirable characteristics do not translate into higher profits, implying some organizational inefficiencies inherent in the holding company structure. This suggests that banks should be allowed to realize the benefits of diversification without limiting them to a particular organizational form.
Hydrogen-oxygen electrolytic regenerative fuel cells
X ray diffraction analysis of matrices of hydrogen-oxygen electrolytic regenerative fuel cell
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The influence of season, photoperiod, and pineal melatonin on immune function.
In addition to the well-documented seasonal cycles of mating and birth, there are also significant seasonal cycles of illness and death among many animal populations. Challenging winter conditions (i.e., low ambient temperature and decreased food availability) can directly induce death via hypothermia, starvation, or shock. Coping with these challenges can also indirectly increase morbidity and mortality by increasing glucocorticoid secretion, which can compromise immune function. Many environmental challenges are recurrent and thus predictable; animals could enhance survival, and presumably increase fitness, if they could anticipate immunologically challenging conditions in order to cope with these seasonal threats to health. The annual cycle of changing photoperiod provides an accurate indicator of time of year and thus allows immunological adjustments prior to the deterioration of conditions. Pineal melatonin codes day length information. Short day lengths enhance several aspects of immune function in laboratory studies, and melatonin appears to mediate many of the enhanced immunological effects of photoperiod. Generally, field studies report compromised immune function during the short days of autumn and winter. The conflict between laboratory and field data is addressed with a multifactor approach. The evidence for seasonal fluctuations in lymphatic tissue size and structure, as well as immune function and disease processes, is reviewed. The role of pineal melatonin and the hormones regulated by melatonin is discussed from an evolutionary and adaptive functional perspective. Finally, the clinically significance of seasonal fluctuations in immune function is presented. Taken together, it appears that seasonal fluctuations in immune parameters, mediated by melatonin, could have profound effects on the etiology and progression of diseases in humans and nonhuman animals. An adaptive functional perspective is critical to gain insights into the interaction among melatonin, immune function, and disease processes
Self-consistent theory of large amplitude collective motion: Applications to approximate quantization of non-separable systems and to nuclear physics
The goal of the present account is to review our efforts to obtain and apply
a ``collective'' Hamiltonian for a few, approximately decoupled, adiabatic
degrees of freedom, starting from a Hamiltonian system with more or many more
degrees of freedom. The approach is based on an analysis of the classical limit
of quantum-mechanical problems. Initially, we study the classical problem
within the framework of Hamiltonian dynamics and derive a fully self-consistent
theory of large amplitude collective motion with small velocities. We derive a
measure for the quality of decoupling of the collective degree of freedom. We
show for several simple examples, where the classical limit is obvious, that
when decoupling is good, a quantization of the collective Hamiltonian leads to
accurate descriptions of the low energy properties of the systems studied. In
nuclear physics problems we construct the classical Hamiltonian by means of
time-dependent mean-field theory, and we transcribe our formalism to this case.
We report studies of a model for monopole vibrations, of Si with a
realistic interaction, several qualitative models of heavier nuclei, and
preliminary results for a more realistic approach to heavy nuclei. Other topics
included are a nuclear Born-Oppenheimer approximation for an {\em ab initio}
quantum theory and a theory of the transfer of energy between collective and
non-collective degrees of freedom when the decoupling is not exact. The
explicit account is based on the work of the authors, but a thorough survey of
other work is included.Comment: 203 pages, many figure
Solar Energetic Particle Events in the 23rd Solar Cycle: Interplanetary Magnetic Field Configuration and Statistical Relationship with Flares and CMEs
We study the influence of the large-scale interplanetary magnetic field
configuration on the solar energetic particles (SEPs) as detected at different
satellites near Earth and on the correlation of their peak intensities with the
parent solar activity. We selected SEP events associated with X and M-class
flares at western longitudes, in order to ensure good magnetic connection to
Earth. These events were classified into two categories according to the global
interplanetary magnetic field (IMF) configuration present during the SEP
propagation to 1AU: standard solar wind or interplanetary coronal mass
ejections (ICMEs). Our analysis shows that around 20% of all particle events
are detected when the spacecraft is immersed in an ICME. The correlation of the
peak particle intensity with the projected speed of the SEP-associated coronal
mass ejection is similar in the two IMF categories of proton and electron
events, . The SEP events within ICMEs show stronger correlation
between the peak proton intensity and the soft X-ray flux of the associated
solar flare, with correlation coefficient 0.670.13, compared to the
SEP events propagating in the standard solar wind, 0.360.13. The
difference is more pronounced for near-relativistic electrons. The main reason
for the different correlation behavior seems to be the larger spread of the
flare longitude in the SEP sample detected in the solar wind as compared to SEP
events within ICMEs. We discuss to which extent observational bias, different
physical processes (particle injection, transport, etc.), and the IMF
configuration can influence the relationship between SEPs and coronal activity.Comment: http://adsabs.harvard.edu.ezproxy.obspm.fr/abs/2013SoPh..282..579
Recent s from IceCube
IceCube is a 1 km neutrino detector now being built at the South Pole.
Its 4800 optical modules will detect Cherenkov radiation from charged particles
produced in neutrino interactions. IceCube will search for neutrinos of
astrophysical origin, with energies from 100 GeV up to eV. It will be
able to separate , and . In addition to detecting
astrophysical neutrinos, IceCube will also search for neutrinos from WIMP
annihilation in the Sun and the Earth, look for low-energy (10 MeV) neutrinos
from supernovae, and search for a host of exotic signatures. With the
associated IceTop surface air shower array, it will study cosmic-ray air
showers.
IceCube construction is now 50% complete. After presenting preliminary
results from the partial detector, I will discuss IceCube's future plans.Comment: Invited talk presented at Neutrino 2008; 7 page
Measuring collaborative emergent behavior in multi-agent reinforcement learning
Multi-agent reinforcement learning (RL) has important implications for the
future of human-agent teaming. We show that improved performance with
multi-agent RL is not a guarantee of the collaborative behavior thought to be
important for solving multi-agent tasks. To address this, we present a novel
approach for quantitatively assessing collaboration in continuous spatial tasks
with multi-agent RL. Such a metric is useful for measuring collaboration
between computational agents and may serve as a training signal for
collaboration in future RL paradigms involving humans.Comment: 1st International Conference on Human Systems Engineering and Design,
6 pages, 2 figures, 1 tabl
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