13,319 research outputs found
A method to estimate the significance of coincident gravitational-wave observations from compact binary coalescence
Coalescing compact binary systems consisting of neutron stars and/or black
holes should be detectable with upcoming advanced gravitational-wave detectors
such as LIGO, Virgo, GEO and {KAGRA}. Gravitational-wave experiments to date
have been riddled with non-Gaussian, non-stationary noise that makes it
challenging to ascertain the significance of an event. A popular method to
estimate significance is to time shift the events collected between detectors
in order to establish a false coincidence rate. Here we propose a method for
estimating the false alarm probability of events using variables commonly
available to search candidates that does not rely on explicitly time shifting
the events while still capturing the non-Gaussianity of the data. We present a
method for establishing a statistical detection of events in the case where
several silver-plated (3--5) events exist but not necessarily any
gold-plated () events. We use LIGO data and a simulated, realistic,
blind signal population to test our method
Credit Cycle and Adverse Selection Effects in Consumer Credit Markets – Evidence from the HELOC Market
We empirically study how the underlying riskiness of the pool of home equity line of credit originations is affected over the credit cycle. Drawing from the largest existing database of U.S. home equity lines of credit, we use county-level aggregates of these loans to estimate panel regressions on the characteristics of the borrowers and their loans, and competing risk hazard regressions on the outcomes of the loans. We show that when the expected unemployment risk of households increases, riskier households tend to borrow more. As a consequence, the pool of households that borrow on home equity lines of credit worsens along both observable and unobservable dimensions. This is an interesting example of a type of dynamic adverse selection that can worsen the risk characteristics of new lending, and suggests another avenue by which the precautionary demand for liquidity may affect borrowing.Home equity loan;adverse selection;liquidity;consumption;housing finance
Dry matter yields and quality of organic lupin/cereal mixtures for wholecrop forage
In view of climate change predictions and the general desirability of increasing the amount of home grown protein, a case exists for the investigation of lupins and lupin/cereal bicrop combinations as wholecrop forage on organic farms. A replicated randomised block trial is described which took place at the Royal Agricultural College, Cirencester, in 2005. This involved spring sown blue, white and yellow lupins, millet, wheat and triticale and lupin/cereal bi-crops. Data for dry matter yields for wholecrop silage, crude protein, MAD fi bre content and estimated ME, are presented for a single harvest. It is concluded that white lupins and white lupin bi-crops with spring wheat or triticale offer the best prospects for a viable wholecrop forage crop in an organic situation
MONTAGE: AGB nucleosynthesis with full s-process calculations
We present MONTAGE, a post-processing nucleosynthesis code that combines a
traditional network for isotopes lighter than calcium with a rapid algorithm
for calculating the s-process nucleosynthesis of the heavier isotopes. The
separation of those parts of the network where only neutron-capture and
beta-decay reactions are significant provides a substantial advantage in
computational efficiency. We present the yields for a complete set of s-process
isotopes for a 3 Mo, Z = 0.02 stellar model, as a demonstration of the utility
of the approach. Future work will include a large grid of models suitable for
use in calculations of Galactic chemical evolution.Comment: 9 pages, 4 figures. Accepted by PAS
Chasing μ
Conducting and semiconducting, π-conjugated polymers are promising materials for micro- and nano-optoelectronic applications because of their widely tunable physical, electrical, and optical properties. These polymers have been used to fabricate a number of electronic devices including field-effect transistors, light-emitting diodes, and photovoltaic cells. However, widespread commercial application of these devices has yet to be realized, due in part to poor electronic transport characteristics and device degradation.
Nanostructuring of conjugated polymers by various methods has demonstrated marked improvements in molecular ordering and electronic transport. In this research, nanoscale, tubular structures of semiconducting polymers fabricated by template wetting nanofabrication procedures are explored. In particular, confinement-induced effects on the electronic carrier transport property mobility, μ, were investigated for both highly ordered and amorphous polymers. Analysis of space-charge-limited currents provided the key means of monitoring transport characteristics and molecular order. The effects of chemical filtration, nanotube diameter, solvent selection, and temperature are examined in detail
A finite subdivision rule for the n-dimensional torus
Cannon, Floyd, and Parry have studied subdivisions of the 2-sphere
extensively, especially those corresponding to 3-manifolds, in an attempt to
prove Cannon's conjecture. There has been a recent interest in generalizing
some of their tools, such as extremal length, to higher dimensions. We define
finite subdivision rules of dimension n, and find an n-1-dimensional finite
subdivision rule for the n-dimensional torus, using a well-known simplicial
decomposition of the hypercube. We hope to expand on this and find finite
subdivision rules for many higher-dimensional manifolds, including hyperbolic
n-manifolds.Comment: Accepted by Geometriae Dedicata; ublished version available onlin
Tamari Lattices and the symmetric Thompson monoid
We investigate the connection between Tamari lattices and the Thompson group
F, summarized in the fact that F is a group of fractions for a certain monoid
F+sym whose Cayley graph includes all Tamari lattices. Under this
correspondence, the Tamari lattice operations are the counterparts of the least
common multiple and greatest common divisor operations in F+sym. As an
application, we show that, for every n, there exists a length l chain in the
nth Tamari lattice whose endpoints are at distance at most 12l/n.Comment: 35page
Lesions mimicking lacrimal gland pleomorphic adenoma
Aim: To report a series of patients with lacrimal gland lesions simulating the clinicoradiological features of lacrimal gland pleomorphic adenoma (LGPA). Methods: Multicentre retrospective, interventional case series. Clinical records of all patients with lesions mimicking LGPA seen in five orbital units were reviewed. Results: The study included 14 patients (seven men and seven women) with a mean age of 50.9 years. The diagnosis of LGPA was made in all cases by experienced orbital surgeons, based on clinicoradiological features, and lacrimal gland excision was performed. Postoperative histology revealed lymphoma (four patients), chronic dacryoadenitis (three patients), adenoid cystic carcinoma (two patients), Sjogren's syndrome (two patients), cavernous haemangioma (one patient), benign lymphoid hyperplasia (one patient) and granulomatous dacryoadenitis (one patient). Comparison with the total number of histologically confirmed LGPA cases seen during the study period revealed that 22.6% of cases of suspected LGPA were misdiagnosed based on clinicoradiological criteria. Conclusions: Many different lesions may mimic the clinicoradiological features of LGPA. The accepted clinicoradiological criteria used for the diagnosis of LGPA have a high false-positive rate, even in experienced hands. Based on this study, the authors believe that fine-needle aspiration biopsy or intraoperative biopsy and frozen section diagnosis may help reduce unnecessary lacrimal gland excision.Venkatesh C Prabhakaran, Paul S Cannon, Alan McNab, Garry Davis, Brett O’Donnell, Peter J Dolman, Raf Ghabrial, Dinesh Selv
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