3,977 research outputs found
The Effect of Transaction Size on Off-the-Run Treasury Prices
A price pressure effect is implied by segmentation in the market for a security. An empirical property of a segmented market is that the price of the security is sensitive to supply and demand conditions for that specific security, absent changes in risk and absent any new information. This paper examines intra-day trading data from the inter-dealer broker market for U.S. Treasury securities and finds that there is a price pressure effect in the off-the-run Treasury market. Thus, securities that would appear to be very close substitutes, i.e., on-the-run and off-the-run Treasury bonds, behave as if there is some degree of market segmentation. There have been several studies of price pressure in the equity market and Treasury bill market but this is the first study of the off-the-run Treasury note and bond market to investigate a price pressure effect using intra-day data. It is also the first study to analyze price pressure through matched pairs of securities that differ only in liquidity and with high frequency data.
Do jumbo-CD holders care about anything?
Uninsured deposits represent a theoretically appealing but relatively untested alternative to subordinated debt for incorporating market discipline into banking supervision. To make the deposit market a useful supervisory tool, it is necessary to know what types of risk are priced by depositors and in what proportions. Using a clustering technique to select from among a large set of potential regressors, as well as a carefully chosen set of control variables, we attempt to determine the types of risk that cause uninsured depositors to react in both the price and quantity dimensions. As a benchmark for economic significance, we estimate similar regressions on supervisory ratings. We find that, in contrast to government supervisors, depositors have not priced most types of risk since 1997. Indeed, the only risk variables that consistently come up as statistically significant are those that measure capital adequacy. Our interpretation of these results is that, because aggregate banking conditions are good, it is not worth depositors' effort to investigate individual bank quality very carefully. We conclude that, in the current economic and regulatory environment, the market is content to delegate most of its monitoring and discipline to the government. To the extent that it does monitor, it only monitors capital. The jumbo-CD market is thus not likely to be of much supervisory use, particularly given that examiners already have good information about capital levels. The depositor emphasis on capital also supports the conjecture that market discipline was responsible for much of the recent capital build-up.Bank deposits ; Bank supervision
Stereo imaging velocimetry for microgravity applications
Stereo imaging velocimetry is the quantitative measurement of three-dimensional flow fields using two sensors recording data from different vantage points. The system described in this paper, under development at NASA Lewis Research Center in Cleveland, Ohio, uses two CCD cameras placed perpendicular to one another, laser disk recorders, an image processing substation, and a 586-based computer to record data at standard NTSC video rates (30 Hertz) and reduce it offline. The flow itself is marked with seed particles, hence the fluid must be transparent. The velocimeter tracks the motion of the particles, and from these we deduce a multipoint (500 or more), quantitative map of the flow. Conceptually, the software portion of the velocimeter can be divided into distinct modules. These modules are: camera calibration, particle finding (image segmentation) and centroid location, particle overlap decomposition, particle tracking, and stereo matching. We discuss our approach to each module, and give our currently achieved speed and accuracy for each where available
Epigenetic Plasticity Drives Adipogenic and Osteogenic Differentiation of Marrow-derived Mesenchymal Stem Cells
Terminal differentiation of multipotent stem cells is achieved through a coordinated cascade of activated transcription factors and epigenetic modifications that drive gene transcription responsible for unique cell fate. Within the mesenchymal lineage, factors such as RUNX2 and PPARγ are indispensable for osteogenesis and adipogenesis, respectively. We therefore investigated genomic binding of transcription factors and accompanying epigenetic modifications that occur during osteogenic and adipogenic differentiation of mouse bone marrow-derived mesenchymal stem cells (MSCs). As assessed by ChIP-sequencing and RNA-sequencing analyses, we found that genes vital for osteogenic identity were linked to RUNX2, C/EBPβ, retinoid X receptor, and vitamin D receptor binding sites, whereas adipocyte differentiation favored PPARγ, retinoid X receptor, C/EBPα, and C/EBPβ binding sites. Epigenetic marks were clear predictors of active differentiation loci as well as enhancer activities and selective gene expression. These marrow-derived MSCs displayed an epigenetic pattern that suggested a default preference for the osteogenic pathway; however, these patterns were rapidly altered near the Adipoq, Cidec, Fabp4, Lipe, Plin1, Pparg, and Cebpa genes during adipogenic differentiation. Surprisingly, we found that these cells also exhibited an epigenetic plasticity that enabled them to trans-differentiate from adipocytes to osteoblasts (and vice versa) after commitment, as assessed by staining, gene expression, and ChIP-quantitative PCR analysis. The osteogenic default pathway may be subverted during pathological conditions, leading to skeletal fragility and increased marrow adiposity during aging, estrogen deficiency, and skeletal unloading. Taken together, our data provide an increased mechanistic understanding of the epigenetic programs necessary for multipotent differentiation of MSCs that may prove beneficial in the development of therapeutic strategies
Information dynamics: patterns of expectation and surprise in the perception of music
This is a postprint of an article submitted for consideration in Connection Science © 2009 [copyright Taylor & Francis]; Connection Science is available online at:http://www.tandfonline.com/openurl?genre=article&issn=0954-0091&volume=21&issue=2-3&spage=8
QSO Absorbing Galaxies at z<~1: Deep Imaging and Spectroscopy in the Field of 3C 336
We present very deep WFPC2 images and FOS spectroscopy from the Hubble Space
Telescope (HST) together with numerous supporting ground-based observations of
the field of the quasar 3C 336 (). The observations are designed
to investigate the nature of galaxies producing metal line absorption systems
in the spectrum of the QSO. Along a single line of sight, we find at least 6
metal line absorption systems (of which 3 are newly discovered) ranging in
redshift from 0.317 to 0.892. Through an extensive program of optical and IR
imaging, QSO spectroscopy, and faint galaxy spectroscopy, we have identified 5
of the 6 metal line absorption systems with luminous (L_K > 0.1 L*_K) galaxies.
These have morphologies ranging from very late-type spiral to S0, and exhibit a
wide range of inclination and position angles with respect to the QSO
sightline. The only unidentified absorber, despite our intensive search, is a
damped Lyman system at . Analysis of the absorption
spectrum suggests that the metal abundances ([Fe/H]) in this system are
similar to those in damped systems at , and to the two other damped
systems for which abundances have been determined at . We have found no
examples of intrinsically faint galaxies () at small impact
parameters that might have been missed as absorber candidates in our previous
ground-based imaging and spectroscopic programs on MgII absorbing galaxies.
There are no bright galaxies (L > 0.1 L_K) within 50h^{-1} kpc which do not
produce detectable metal lines (of Mg II 2796, 2803 and/or C IV 1548, 1550) in
the QSO spectrum. All of these results generally support the inferences which
we have previously reached from a larger survey for absorption-selected
galaxies at z\simlt 1.Comment: 32 pages latex (AAS v4.0 style). 8 Postscript figures (including HST
plate) available at ftp://astro.caltech.edu/users/ccs/3c336_figs.ps.gz .
Submitted to Ap
West Nile virus in the New World: potential impacts on bird species
The past five years have seen the arrival and extremely rapid expansion of West Nile virus
(WNV) in the Western Hemisphere. The rapid sweep across North America has permitted
little time for developing knowledge of the virus’s potential impacts on wildlife in
the New World. Given this information gap, we here summarize for the ornithological
community what is known or can be anticipated for WNV’s effect on bird communities in
coming years. Our particular focus is on impacts of WNV on the conservation status of
birds, the principal vertebrate reservoir for the virus
Molecular insights into mineralotropic hormone inter-regulation
The regulation of mineral homeostasis involves the three mineralotropic hormones PTH, FGF23 and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Early research efforts focused on PTH and 1,25(OH)2D3 and more recently on FGF23 have revealed that each of these hormones regulates the expression of the other two. Despite early suggestions of transcriptional processes, it has been only recently that research effort have begun to delineate the genomic mechanisms underpinning this regulation for 1,25(OH)2D3 and FGF23; the regulation of PTH by 1,25(OH)2D3, however, remains obscure. We review here our molecular understanding of how PTH induces Cyp27b1 expression, the gene encoding the enzyme responsible for the synthesis of 1,25(OH)2D3. FGF23 and 1,25(OH)2D3, on the other hand, function by suppressing production of 1,25(OH)2D3. PTH stimulates the PKA-induced recruitment of CREB and its coactivator CBP at CREB occupied sites within the kidney-specific regulatory regions of Cyp27b1. PKA activation also promotes the nuclear translocation of SIK bound coactivators such as CRTC2, where it similarly interacts with CREB occupied Cyp27b1 sites. The negative actions of both FGF23 and 1,25(OH)2D3 appear to suppress Cyp27b1 expression by opposing the recruitment of CREB coactivators at this gene. Reciprocal gene actions are seen at Cyp24a1, the gene encoding the enzyme that degrades 1,25(OH)2D3, thereby contributing to the overall regulation of blood levels of 1,25(OH)2D3. Relative to PTH regulation, we summarize what is known of how 1,25(OH)2D3 regulates PTH suppression. These studies suggest that it is not 1,25(OH)2D3 that controls PTH levels in healthy subjects, but rather calcium itself. Finally, we describe current progress using an in vivo approach that furthers our understanding of the regulation of Fgf23 expression by PTH and 1,25(OH)2D3 and provide the first evidence that P may act to induce Fgf23 expression via a complex transcriptional mechanism in bone. It is clear, however, that additional advances will need to be made to further our understanding of the inter-regulation of each of these hormonal genes
Yttrium-90 microsphere induced gastrointestinal tract ulceration
© 2008 South et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
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