1,825 research outputs found
The role of financing frictions in agricultural investment decisions: an analysis pre and post financial crisis
This paper uses a fundamental Q model of investment to consider the role played by financing frictions in agricultural investment decisions, controlling econometrically for censoring, heterogeneity and errors-in-variables. Our findings suggest that farmer's investment decisions are not driven by market fundamentals. We find some evidence that debt overhang restricts investment but investment is not dependent on liquidity or internal funds. The role of financing frictions in determining investment decisions changes in the post-financial crisis period when debt overhang becomes a significant impediment to farm investment. The evidence suggests that farmers increasingly rely on internal liquidity to drive investment. Finally, we find no evidence that farmers use on-farm capital to fund on-farm investment.Credit Constraints, Firm Level Investment, Tobin's Q, Debt, Agricultural Finance, G31, G32, F34,
The MultiSite Spectroscopic Telescope campaign: 2m spectroscopy of the V361 Hya variable PG1605+072
We present results and analysis for the 2m spectroscopic part of the
MultiSite Spectroscopic Telescope (MSST) campaign undertaken in May/June 2002.
The goal of the project was to observe the pulsating subdwarf B star PG1605+072
simultaneously in velocity and photometry and to resolve as many of the >50
known modes as possible, which will allow a detailed asteroseismological
analysis. We have obtained over 150 hours of spectroscopy, leading to an
unprecedented noise level of only 207m/s. We report here the detection of 20
frequencies in velocity, with two more likely just below our detection
threshold. In particular, we detect 6 linear combinations, making PG1605+072
only the second star known to show such frequencies in velocity. We investigate
the phases of these combinations and their parent modes and find relationships
between them that cannot be easily understood based on current theory. These
observations, when combined with our simultaneous photometry, should allow
asteroseismology of this most complicated of sdB pulsators.Comment: 9 pages, 5 figures, accepted for publication in A&A; Figure 1 at
lower resolution than accepted versio
Radial velocity variations of the pulsating subdwarf B star PG 1605+072
We present an analysis of high-speed spectroscopy of the pulsating subdwarf B
star PG 1605+072. Periodic radial motions are detected at frequencies similar
to those reported for photometric variations in the star, with amplitudes of up
to 6 km/s. Differences between relative strengths for given frequency peaks for
our velocity data and previously measured photometry are probably a result of
shifting of power between modes over time. Small differences in the detected
frequencies may also indicate mode-shifting. We report the detection of
line-shape variations using the moments of the cross correlation function
profiles. It may be possible to use the moments to identify the star's
pulsation modes.Comment: 5 pages, 6 figure
The molecular genetic analysis of the expanding pachyonychia congenita case collection
BACKGROUND: Pachyonychia congenita (PC) is a rare autosomal dominant keratinizing disorder characterized by severe, painful, palmoplantar keratoderma and nail dystrophy, often accompanied by oral leucokeratosis, cysts and follicular keratosis. It is caused by mutations in one of five keratin genes: KRT6A, KRT6B, KRT6C, KRT16 or KRT17. OBJECTIVES: To identify mutations in 84 new families with a clinical diagnosis of PC, recruited by the International Pachyonychia Congenita Research Registry during the last few years. METHODS: Genomic DNA isolated from saliva or peripheral blood leucocytes was amplified using primers specific for the PC-associated keratin genes and polymerase chain reaction products were directly sequenced. RESULTS: Mutations were identified in 84 families in the PC-associated keratin genes, comprising 46 distinct keratin mutations. Fourteen were previously unreported mutations, bringing the total number of different keratin mutations associated with PC to 105. CONCLUSIONS: By identifying mutations in KRT6A, KRT6B, KRT6C, KRT16 or KRT17, this study has confirmed, at the molecular level, the clinical diagnosis of PC in these families
Identifying novel hypoxia-associated markers of chemoresistance in ovarian cancer
BACKGROUND
Ovarian cancer is associated with poor long-term survival due to late diagnosis and development of chemoresistance. Tumour hypoxia is associated with many features of tumour aggressiveness including increased cellular proliferation, inhibition of apoptosis, increased invasion and metastasis, and chemoresistance, mostly mediated through hypoxia-inducible factor (HIF)-1α. While HIF-1α has been associated with platinum resistance in a variety of cancers, including ovarian, relatively little is known about the importance of the duration of hypoxia. Similarly, the gene pathways activated in ovarian cancer which cause chemoresistance as a result of hypoxia are poorly understood. This study aimed to firstly investigate the effect of hypoxia duration on resistance to cisplatin in an ovarian cancer chemoresistance cell line model and to identify genes whose expression was associated with hypoxia-induced chemoresistance.
METHODS
Cisplatin-sensitive (A2780) and cisplatin-resistant (A2780cis) ovarian cancer cell lines were exposed to various combinations of hypoxia and/or chemotherapeutic drugs as part of a 'hypoxia matrix' designed to cover clinically relevant scenarios in terms of tumour hypoxia. Response to cisplatin was measured by the MTT assay. RNA was extracted from cells treated as part of the hypoxia matrix and interrogated on Affymetrix Human Gene ST 1.0 arrays. Differential gene expression analysis was performed for cells exposed to hypoxia and/or cisplatin. From this, four potential markers of chemoresistance were selected for evaluation in a cohort of ovarian tumour samples by RT-PCR.
RESULTS
Hypoxia increased resistance to cisplatin in A2780 and A2780cis cells. A plethora of genes were differentially expressed in cells exposed to hypoxia and cisplatin which could be associated with chemoresistance. In ovarian tumour samples, we found trends for upregulation of ANGPTL4 in partial responders and down-regulation in non-responders compared with responders to chemotherapy; down-regulation of HER3 in partial and non-responders compared to responders; and down-regulation of HIF-1α in non-responders compared with responders.
CONCLUSION
This study has further characterized the relationship between hypoxia and chemoresistance in an ovarian cancer model. We have also identified many potential biomarkers of hypoxia and platinum resistance and provided an initial validation of a subset of these markers in ovarian cancer tissues
Polysaccharide utilization loci and nutritional specialization in a dominant group of butyrate-producing human colonic Firmicutes
Acknowledgements The Rowett Institute of Nutrition and Health (University of Aberdeen) receives financial support from the Scottish Government Rural and Environmental Sciences and Analytical Services (RESAS). POS is a PhD student supported by the Scottish Government (RESAS) and the Science Foundation Ireland, through a centre award to the APC Microbiome Institute, Cork, Ireland. Data Summary The high-quality draft genomes generated in this work were deposited at the European Nucleotide Archive under the following accession numbers: 1. Eubacterium rectale T1-815; CVRQ01000001âCVRQ0100 0090: http://www.ebi.ac.uk/ena/data/view/PRJEB9320 2. Roseburia faecis M72/1; CVRR01000001âCVRR010001 01: http://www.ebi.ac.uk/ena/data/view/PRJEB9321 3. Roseburia inulinivorans L1-83; CVRS01000001âCVRS0 100 0151: http://www.ebi.ac.uk/ena/data/view/PRJEB9322Peer reviewedPublisher PD
Three ways to solve the orbit of KIC11558725: a 10 day beaming sdB+WD binary with a pulsating subdwarf
The recently discovered subdwarf B (sdB) pulsator KIC11558725 features a rich
g-mode frequency spectrum, with a few low-amplitude p-modes at short periods,
and is a promising target for a seismic study aiming to constrain the internal
structure of this star, and of sdB stars in general.
We have obtained ground-based spectroscopic Balmer-line radial-velocity
measurements of KIC11558725, spanning the 2010 and 2011 observing seasons. From
these data we have discovered that KIC11558725 is a binary with period P=10.05
d, and that the radial-velocity amplitude of the sdB star is 58 km/s.
Consequently the companion of the sdB star has a minimum mass of 0.63 M\odot,
and is therefore most likely an unseen white dwarf.
We analyse the near-continuous 2010-2011 Kepler light curve to reveal orbital
Doppler-beaming light variations at the 238 ppm level, which is consistent with
the observed spectroscopic orbital radial-velocity amplitude of the subdwarf.
We use the strongest 70 pulsation frequencies in the Kepler light curve of the
subdwarf as clocks to derive a third consistent measurement of the orbital
radial-velocity amplitude, from the orbital light-travel delay.
We use our high signal-to-noise average spectra to study the atmospheric
parameters of the sdB star, deriving Teff = 27 910K and log g = 5.41 dex, and
find that carbon, nitrogen and oxygen are underabundant relative to the solar
mixture.
Furthermore, we extract more than 160 significant frequencies from the Kepler
light curve. We investigate the pulsation frequencies for expected period
spacings and rotational splittings. We find period-spacing sequences of
spherical-harmonic degrees \ell=1 and \ell=2, and we associate a large fraction
of the g-modes in KIC11558725 with these sequences. From frequency splittings
we conclude that the subdwarf is rotating subsynchronously with respect to the
orbit
- âŠ