4,506 research outputs found
Three Essays on External Sources of Corporate Governance
Corporate governance is the system by which corporations are controlled. External sources of governance include regulatory and market mechanisms as well as the interplay of goals between managers, the board, and shareholders. Other external sources can include informal institutions which can shape goals as well as suggested by institutional theory, effectively constrain human behavior. In my first essay, I argue that foreign direct investors can act as agents of change in corporate governance. Investigating changes in ownership and control of Swedish firms, I find that active foreign investors\u27 participation move firms away from a Swedish stakeholder orientation toward an Anglo-American shareholder wealth maximization focus. In my second essay, I explore the relationship of informal and formal institutions on microfinance institutions (MFI). Investigating the outreach and performance of MFIs in developing nations, I find that strong formal institutions foster better efficiency and outreach while strong informal institutions\u27 impact is limited to better outreach. In my third essay, I investigate the apparent lack of market discipline in the bank subordinated debt market leading up to the 2008 finance crisis. I find that subordinated debt holders were caught off guard by the suddenness and magnitude of the crisis. I argue that bank opacity created a vulnerable environment in the banking industry that contributed to this collapse
Constraining the Atmospheric Composition of the Day-Night Terminators of HD 189733b : Atmospheric Retrieval with Aerosols
A number of observations have shown that Rayleigh scattering by aerosols
dominates the transmission spectrum of HD 189733b at wavelengths shortward of 1
m. In this study, we retrieve a range of aerosol distributions consistent
with transmission spectroscopy between 0.3-24 m that were recently
re-analyzed by Pont et al. (2013). To constrain the particle size and the
optical depth of the aerosol layer, we investigate the degeneracies between
aerosol composition, temperature, planetary radius, and molecular abundances
that prevent unique solutions for transit spectroscopy. Assuming that the
aerosol is composed of MgSiO, we suggest that a vertically uniform aerosol
layer over all pressures with a monodisperse particle size smaller than about
0.1 m and an optical depth in the range 0.002-0.02 at 1 m provides
statistically meaningful solutions for the day/night terminator regions of HD
189733b. Generally, we find that a uniform aerosol layer provide adequate fits
to the data if the optical depth is less than 0.1 and the particle size is
smaller than 0.1 m, irrespective of the atmospheric temperature, planetary
radius, aerosol composition, and gaseous molecules. Strong constraints on the
aerosol properties are provided by spectra at wavelengths shortward of 1 m
as well as longward of 8 m, if the aerosol material has absorption
features in this region. We show that these are the optimal wavelengths for
quantifying the effects of aerosols, which may guide the design of future space
observations. The present investigation indicates that the current data offer
sufficient information to constrain some of the aerosol properties of
HD189733b, but the chemistry in the terminator regions remains uncertain.Comment: Transferred to ApJ and accepted. 11 pages, 10 figures, 1 tabl
Improving DRAM Performance by Parallelizing Refreshes with Accesses
Modern DRAM cells are periodically refreshed to prevent data loss due to
leakage. Commodity DDR DRAM refreshes cells at the rank level. This degrades
performance significantly because it prevents an entire rank from serving
memory requests while being refreshed. DRAM designed for mobile platforms,
LPDDR DRAM, supports an enhanced mode, called per-bank refresh, that refreshes
cells at the bank level. This enables a bank to be accessed while another in
the same rank is being refreshed, alleviating part of the negative performance
impact of refreshes. However, there are two shortcomings of per-bank refresh.
First, the per-bank refresh scheduling scheme does not exploit the full
potential of overlapping refreshes with accesses across banks because it
restricts the banks to be refreshed in a sequential round-robin order. Second,
accesses to a bank that is being refreshed have to wait.
To mitigate the negative performance impact of DRAM refresh, we propose two
complementary mechanisms, DARP (Dynamic Access Refresh Parallelization) and
SARP (Subarray Access Refresh Parallelization). The goal is to address the
drawbacks of per-bank refresh by building more efficient techniques to
parallelize refreshes and accesses within DRAM. First, instead of issuing
per-bank refreshes in a round-robin order, DARP issues per-bank refreshes to
idle banks in an out-of-order manner. Furthermore, DARP schedules refreshes
during intervals when a batch of writes are draining to DRAM. Second, SARP
exploits the existence of mostly-independent subarrays within a bank. With
minor modifications to DRAM organization, it allows a bank to serve memory
accesses to an idle subarray while another subarray is being refreshed.
Extensive evaluations show that our mechanisms improve system performance and
energy efficiency compared to state-of-the-art refresh policies and the benefit
increases as DRAM density increases.Comment: The original paper published in the International Symposium on
High-Performance Computer Architecture (HPCA) contains an error. The arxiv
version has an erratum that describes the error and the fix for i
Rotation in liquid He: Lessons from a toy model
This paper presents an analysis of a model problem, consisting of two
interacting rigid rings, for the rotation of molecules in liquid He. Due to
Bose symmetry, the excitation of the rotor corresponding to a ring of N helium
atoms is restricted to states with integer multiples of N quanta of angular
momentum. This minimal model shares many of the same features of the rotational
spectra that have been observed for molecules in nanodroplets of helium atoms. In particular, this model predicts, for the first time,
the very large enhancement of the centrifugal distortion constants that have
been observed experimentally. It also illustrates the different effects of
increasing rotational velocity by increases in angular momentum quantum number
or by increasing the rotational constant of the molecular rotor. It is found
that fixed node, diffusion Monte Carlo and a hydrodynamic model provide upper
and lower bounds on the size of the effective rotational constant of the
molecular rotor when coupled to the helium
- …