1,086 research outputs found
An Empirical Examination of Compensation of REIT Managers
Principal-agent literature finds that manager and owner incentives can be aligned with performance contingent contracts. We investigate the compensation of Real Estate Investment Trust (REIT) industry executives. The competitive nature of mortgage and equity markets, in conjunction with the corporate tax exemption available when REITs distribute most of their earnings as dividends, is likely to influence the compensation of REIT managers. Executive compensation is modeled as a function of revenues and unexpected profit. After transforming the model to reduce collinearity and heteroskedasticity, we find compensation to be generally positively related to revenue. We also find unexpected profit to be generally insignificantly related to compensation, but positively related in those cases where it is significant.
Mortgage Lenders' Market Response to a Landmark Regulatory Decision Based on Fair Lending Compliance
Regulation of real estate lending has substantially increased in the past decade. Government efforts to improve compliance with Community Reinvestment Act mandates are evidence of increased emphasis on racial equal opportunity in loan origination. To investigate the impact of these efforts, this paper examines the Federal Reserve Bank rejection of Shawmut National Corporation's application to buy New Dartmouth Bank. Rejection was based on Shawmut's poor compliance with fair-lending guidelines. Testing finds significant negative abnormal stock returns for samples of mortgage lenders on the announcement day of Shawmut's application rejection. In addition, cross-sectional analysis reveals an inverse relationship between national banks' cumulative abnormal returns (CARs) and a measure of fair lending.
Reclaiming human machine nature
Extending and modifying his domain of life by artifact production is one of
the main characteristics of humankind. From the first hominid, who used a wood
stick or a stone for extending his upper limbs and augmenting his gesture
strength, to current systems engineers who used technologies for augmenting
human cognition, perception and action, extending human body capabilities
remains a big issue. From more than fifty years cybernetics, computer and
cognitive sciences have imposed only one reductionist model of human machine
systems: cognitive systems. Inspired by philosophy, behaviorist psychology and
the information treatment metaphor, the cognitive system paradigm requires a
function view and a functional analysis in human systems design process.
According that design approach, human have been reduced to his metaphysical and
functional properties in a new dualism. Human body requirements have been left
to physical ergonomics or "physiology". With multidisciplinary convergence, the
issues of "human-machine" systems and "human artifacts" evolve. The loss of
biological and social boundaries between human organisms and interactive and
informational physical artifact questions the current engineering methods and
ergonomic design of cognitive systems. New developpment of human machine
systems for intensive care, human space activities or bio-engineering sytems
requires grounding human systems design on a renewed epistemological framework
for future human systems model and evidence based "bio-engineering". In that
context, reclaiming human factors, augmented human and human machine nature is
a necessityComment: Published in HCI International 2014, Heraklion : Greece (2014
Properties of Nested Sampling
Nested sampling is a simulation method for approximating marginal likelihoods
proposed by Skilling (2006). We establish that nested sampling has an
approximation error that vanishes at the standard Monte Carlo rate and that
this error is asymptotically Gaussian. We show that the asymptotic variance of
the nested sampling approximation typically grows linearly with the dimension
of the parameter. We discuss the applicability and efficiency of nested
sampling in realistic problems, and we compare it with two current methods for
computing marginal likelihood. We propose an extension that avoids resorting to
Markov chain Monte Carlo to obtain the simulated points.Comment: Revision submitted to Biometrik
Sequential quasi-Monte Carlo: Introduction for Non-Experts, Dimension Reduction, Application to Partly Observed Diffusion Processes
SMC (Sequential Monte Carlo) is a class of Monte Carlo algorithms for
filtering and related sequential problems. Gerber and Chopin (2015) introduced
SQMC (Sequential quasi-Monte Carlo), a QMC version of SMC. This paper has two
objectives: (a) to introduce Sequential Monte Carlo to the QMC community, whose
members are usually less familiar with state-space models and particle
filtering; (b) to extend SQMC to the filtering of continuous-time state-space
models, where the latent process is a diffusion. A recurring point in the paper
will be the notion of dimension reduction, that is how to implement SQMC in
such a way that it provides good performance despite the high dimension of the
problem.Comment: To be published in the proceedings of MCMQMC 201
Harold Jeffreys's Theory of Probability Revisited
Published exactly seventy years ago, Jeffreys's Theory of Probability (1939)
has had a unique impact on the Bayesian community and is now considered to be
one of the main classics in Bayesian Statistics as well as the initiator of the
objective Bayes school. In particular, its advances on the derivation of
noninformative priors as well as on the scaling of Bayes factors have had a
lasting impact on the field. However, the book reflects the characteristics of
the time, especially in terms of mathematical rigor. In this paper we point out
the fundamental aspects of this reference work, especially the thorough
coverage of testing problems and the construction of both estimation and
testing noninformative priors based on functional divergences. Our major aim
here is to help modern readers in navigating in this difficult text and in
concentrating on passages that are still relevant today.Comment: This paper commented in: [arXiv:1001.2967], [arXiv:1001.2968],
[arXiv:1001.2970], [arXiv:1001.2975], [arXiv:1001.2985], [arXiv:1001.3073].
Rejoinder in [arXiv:0909.1008]. Published in at
http://dx.doi.org/10.1214/09-STS284 the Statistical Science
(http://www.imstat.org/sts/) by the Institute of Mathematical Statistics
(http://www.imstat.org
Intrinsic time gravity and the Lichnerowicz-York equation
We investigate the effect on the Hamiltonian structure of general relativity
of choosing an intrinsic time to fix the time slicing. 3-covariance with
momentum constraint is maintained, but the Hamiltonian constraint is replaced
by a dynamical equation for the trace of the momentum. This reveals a very
simple structure with a local reduced Hamiltonian. The theory is easily
generalised; in particular, the square of the Cotton-York tensor density can be
added as an extra part of the potential while at the same time maintaining the
classic 2 + 2 degrees of freedom. Initial data construction is simple in the
extended theory; we get a generalised Lichnerowicz-York equation with nice
existence and uniqueness properties. Adding standard matter fields is quite
straightforward.Comment: 4 page
Revised genomic structure of the human ghrelin gene and identification of novel exons, alternative splice variants and natural antisense transcripts
Background Ghrelin is a multifunctional peptide hormone expressed in a range of normal tissues and pathologies. It has been reported that the human ghrelin gene consists of five exons which span 5 kb of genomic DNA on chromosome 3 and includes a 20 bp non-coding first exon (20 bp exon 0). The availability of bioinformatic tools enabling comparative analysis and the finalisation of the human genome prompted us to re-examine the genomic structure of the ghrelin locus. Results We have demonstrated the presence of an additional novel exon (exon -1) and 5' extensions to exon 0 and 1 using comparative in silico analysis and have demonstrated their existence experimentally using RT-PCR and 5' RACE. A revised exon-intron structure demonstrates that the human ghrelin gene spans 7.2 kb and consists of six rather than five exons. Several ghrelin gene-derived splice forms were detected in a range of human tissues and cell lines. We have demonstrated ghrelin gene-derived mRNA transcripts that do not code for ghrelin, but instead may encode the C-terminal region of full-length preproghrelin (C-ghrelin, which contains the coding region for obestatin) and a transcript encoding obestatin-only. Splice variants that differed in their 5' untranslated regions were also found, suggesting a role of these regions in the post-transcriptional regulation of preproghrelin translation. Finally, several natural antisense transcripts, termed ghrelinOS (ghrelin opposite strand) transcripts, were demonstrated via orientation-specific RT-PCR, 5' RACE and in silico analysis of ESTs and cloned amplicons. Conclusion The sense and antisense alternative transcripts demonstrated in this study may function as non-coding regulatory RNA, or code for novel protein isoforms. This is the first demonstration of putative obestatin and C-ghrelin specific transcripts and these findings suggest that these ghrelin gene-derived peptides may also be produced independently of preproghrelin. This study reveals several novel aspects of the ghrelin gene and suggests that the ghrelin locus is far more complex than previously recognised
EPSAT-SG: a satellite method for precipitation estimation; its concepts and implementation for the AMMA experiment
International audienceThis paper presents a new rainfall estimation method, EPSAT-SG which is a frame for method design. The first implementation has been carried out to meet the requirement of the AMMA database on a West African domain. The rainfall estimation relies on two intermediate products: a rainfall probability and a rainfall potential intensity. The first one is computed from MSG/SEVIRI by a feed forward neural network. First evaluation results show better properties than direct precipitation intensity assessment by geostationary satellite infra-red sensors. The second product can be interpreted as a conditional rainfall intensity and, in the described implementation, it is extracted from GPCP-1dd. Various implementation options are discussed and comparison of this embedded product with 3B42 estimates demonstrates the importance of properly managing the temporal discontinuity. The resulting accumulated rainfall field can be presented as a GPCP downscaling. A validation based on ground data supplied by AGRHYMET (Niamey) indicates that the estimation error has been reduced in this process. The described method could be easily adapted to other geographical area and operational environment
Complex organisation and structure of the ghrelin antisense strand gene GHRLOS, a candidate non-coding RNA gene
<p>Abstract</p> <p>Background</p> <p>The peptide hormone ghrelin has many important physiological and pathophysiological roles, including the stimulation of growth hormone (GH) release, appetite regulation, gut motility and proliferation of cancer cells. We previously identified a gene on the opposite strand of the ghrelin gene, ghrelinOS (<it>GHRLOS</it>), which spans the promoter and untranslated regions of the ghrelin gene (<it>GHRL</it>). Here we further characterise <it>GHRLOS</it>.</p> <p>Results</p> <p>We have described <it>GHRLOS </it>mRNA isoforms that extend over 1.4 kb of the promoter region and 106 nucleotides of exon 4 of the ghrelin gene, <it>GHRL</it>. These <it>GHRLOS </it>transcripts initiate 4.8 kb downstream of the terminal exon 4 of <it>GHRL </it>and are present in the 3' untranslated exon of the adjacent gene <it>TATDN2 </it>(TatD DNase domain containing 2). Interestingly, we have also identified a putative non-coding <it>TATDN2-GHRLOS </it>chimaeric transcript, indicating that <it>GHRLOS </it>RNA biogenesis is extremely complex. Moreover, we have discovered that the 3' region of <it>GHRLOS </it>is also antisense, in a tail-to-tail fashion to a novel terminal exon of the neighbouring <it>SEC13 </it>gene, which is important in protein transport. Sequence analyses revealed that <it>GHRLOS </it>is riddled with stop codons, and that there is little nucleotide and amino-acid sequence conservation of the <it>GHRLOS </it>gene between vertebrates. The gene spans 44 kb on 3p25.3, is extensively spliced and harbours multiple variable exons. We have also investigated the expression of <it>GHRLOS </it>and found evidence of differential tissue expression. It is highly expressed in tissues which are emerging as major sites of non-coding RNA expression (the thymus, brain, and testis), as well as in the ovary and uterus. In contrast, very low levels were found in the stomach where sense, <it>GHRL </it>derived RNAs are highly expressed.</p> <p>Conclusion</p> <p><it>GHRLOS </it>RNA transcripts display several distinctive features of non-coding (ncRNA) genes, including 5' capping, polyadenylation, extensive splicing and short open reading frames. The gene is also non-conserved, with differential and tissue-restricted expression. The overlapping genomic arrangement of <it>GHRLOS </it>with the ghrelin gene indicates that it is likely to have interesting regulatory and functional roles in the ghrelin axis.</p
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