644 research outputs found
Idiosyncratic Risk and Short Interest Analysis for Canadian Large Cap Stocks
While previous studies have focused on the relation between idiosyncratic risk and short interest in US stock markets, we test whether the Canadian market shows the same symptoms in costs limiting arbitrage. In order to measure arbitrage cost, we use idiosyncratic risk and use it as a proxy to determine the cost level. To prevent any ambiguity and bias in our result, we use commonly recognized indexes to measure both transaction and holding costs. Consistent with the similar study conducted in U.S., we find that high Short Interest Canadian stocks appear to have higher idiosyncratic risk that is significant enough to affect investors’ decisions
Transport Measurements on Nano-engineered Two Dimensional Superconducting Wire Networks
Superconducting triangular Nb wire networks with high normal-state resistance
are fabricated by using a negative tone hydrogen silsesquioxane (HSQ) resist.
Robust magnetoresistance oscillations are observed up to high magnetic fields
and maintained at low temperatures, due to the eective reduction of wire
dimensions. Well-defined dips appear at integral and rational values (1/2, 1/3,
1/4) of the reduced flux f = Phi/Phi_0, which is the first observation in the
triangular wire networks. These results are well consistent with theoretical
calculations for the reduced critical temperature as a function of f.Comment: 4 pages, 3 figure
The study of Seyfert 2 galaxies with and without infrared broad lines
From the literature, we construct from literature a sample of 25 Seyfert 2
galaxies (S2s) with a broad line region detected in near infrared spectroscopy
and 29 with NIR BLR which was detected. We find no significant difference
between the nuclei luminosity (extinction-corrected [OIII]~5007) and infrared
color between the two populations, suggesting that the
non-detections of NIR BLR could not be due to low AGN luminosity or
contamination from the host galaxy. As expected, we find significantly lower
X-ray obscurations in Seyfert 2s with NIR BLR detection, supporting the
unification scheme. However, such a scheme was challenged by the detection of
NIR BLR in heavily X-ray obscured sources, especially in six of them with
Compton-thick X-ray obscuration. The discrepancy could be solved by the clumpy
torus model and we propose a toy model demonstrating that IR-thin X-ray-thick
S2s could be viewed at intermediate inclinations, and compared with those
IR-thick X-ray-thick S2s. We note that two of the IR-thin X-ray-thick S2s (NGC
1386 and NGC 7674) experienced X-ray transitions, i.e. from Compton-thin to
Compton-thick appearance or vice versa based on previous X-ray observations,
suggesting that X-ray transitions could be common in this special class of
objects
The Power of Transient Piezometric Head Data in Inverse Modeling: An Application of the Localized Normal-score EnKF with Covariance Inflation in a Heterogenous Bimodal Hydraulic Conductivity Field
The localized normal-score ensemble Kalman filter (NS-EnKF) coupled with covariance inflation is used to characterize the spatial variability of a channelized bimodal hydraulic conductivity field, for which the only existing prior information about conductivity is its univariate marginal distribution. We demonstrate that we can retrieve the main patterns of the reference field by assimilating a sufficient number of piezometric observations using the NS-EnKF. The possibility of characterizing the conductivity spatial variability using only piezometric head data shows the importance of accounting for these data in inverse modeling.The first author acknowledges the financial support from the China Scholarship Council (CSC). Financial support to carry out this work was also received from the Spanish Ministry of Science and Innovation through project CGL2011-23295.Xu, T.; Gómez-Hernández, JJ.; Zhou, H.; Li, L. (2013). The Power of Transient Piezometric Head Data in Inverse Modeling: An Application of the Localized Normal-score EnKF with Covariance Inflation in a Heterogenous Bimodal Hydraulic Conductivity Field. Advances in Water Resources. 54:100-118. https://doi.org/10.1016/j.advwatres.2013.01.006S1001185
Inverse sequential simulation: Performance and implementation details
For good groundwater flow and solute transport numerical modeling, it is important to characterize the formation
properties. In this paper, we analyze the performance and important implementation details of a
new approach for stochastic inverse modeling called inverse sequential simulation (iSS). This approach is
capable of characterizing conductivity fields with heterogeneity patterns difficult to capture by standard
multiGaussian-based inverse approaches. The method is based on the multivariate sequential simulation
principle, but the covariances and cross-covariances used to compute the local conditional probability distributions
are computed by simple co-kriging which are derived from an ensemble of conductivity and piezometric
head fields, in a similar manner as the experimental covariances are computed in an ensemble Kalman
filtering. A sensitivity analysis is performed on a synthetic aquifer regarding the number of members of the
ensemble of realizations, the number of conditioning data, the number of piezometers at which piezometric
heads are observed, and the number of nodes retained within the search neighborhood at the moment of
computing the local conditional probabilities. The results show the importance of having a sufficiently large
number of all of the mentioned parameters for the algorithm to characterize properly hydraulic conductivity
fields with clear non-multiGaussian features.
© 2015 Elsevier Ltd. All rights reserved.The first author acknowledgs the financial support from the China Scholarship Council (CSC [2010]3010). Financial support to carry out this work was also received from the Spanish Ministry of Economy and Competitiveness through Project CGL2014-59841-P. We thank the three reviewers for their thorough review and their insightful comments, which have helped to improve the final manuscript.Xu, T.; Gómez-Hernández, JJ. (2015). Inverse sequential simulation: Performance and implementation details. Advances in Water Resources. 86B:311-326. https://doi.org/10.1016/j.advwatres.2015.04.015S31132686
Plant species with extremely small populations (PSESP) in China: A seed and spore biology perspective
AbstractApproximately one fifth of the world's plants are at risk of extinction. Of these, a significant number exist as populations of few individuals, with limited distribution ranges and under enormous pressure due to habitat destruction. In China, these most-at-risk species are described as ‘plant species with extremely small populations’ (PSESP). Implementing conservation action for such listed species is urgent. Storing seeds is one of the main means of ex situ conservation for flowering plants. Spore storage could provide a simple and economical method for fern ex situ conservation. Seed and spore germination in nature is a critical step in species regeneration and thus in situ conservation. But what is known about the seed and spore biology (storage and germination) of at-risk species? We have used China's PSESP (the first group listing) as a case study to understand the gaps in knowledge on propagule biology of threatened plant species. We found that whilst germination information is available for 28 species (23% of PSESP), storage characteristics are only known for 8% of PSESP (10 species). Moreover, we estimate that 60% of the listed species may require cryopreservation for long-term storage. We conclude that comparative biology studies are urgently needed on the world's most threatened taxa so that conservation action can progress beyond species listing
Search for Production via Trilepton Final States in collisions at TeV
We have searched for associated production of the lightest chargino,
, and next-to-lightest neutralino, , of the
Minimal Supersymmetric Standard Model in collisions at
\mbox{ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron
collider. Data corresponding to an integrated luminosity of 12.5 \ipb
were examined for events containing three isolated leptons. No evidence for
pair production was found. Limits on
BrBr are
presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures
will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted
to Physical Review Letters. Replace comments - Had to resumbmit version with
EPSF directive
Second Generation Leptoquark Search in p\bar{p} Collisions at = 1.8 TeV
We report on a search for second generation leptoquarks with the D\O\
detector at the Fermilab Tevatron collider at = 1.8 TeV.
This search is based on 12.7 pb of data. Second generation leptoquarks
are assumed to be produced in pairs and to decay into a muon and quark with
branching ratio or to neutrino and quark with branching ratio
. We obtain cross section times branching ratio limits as a function
of leptoquark mass and set a lower limit on the leptoquark mass of 111
GeV/c for and 89 GeV/c for at the 95%\
confidence level.Comment: 18 pages, FERMILAB-PUB-95/185-
The Azimuthal Decorrelation of Jets Widely Separated in Rapidity
This study reports the first measurement of the azimuthal decorrelation
between jets with pseudorapidity separation up to five units. The data were
accumulated using the D{\O}detector during the 1992--1993 collider run of the
Fermilab Tevatron at 1.8 TeV. These results are compared to
next--to--leading order (NLO) QCD predictions and to two leading--log
approximations (LLA) where the leading--log terms are resummed to all orders in
. The final state jets as predicted by NLO QCD
show less azimuthal decorrelation than the data. The parton showering LLA Monte
Carlo {\small HERWIG} describes the data well; an analytical LLA prediction
based on BFKL resummation shows more decorrelation than the data.Comment: 6 pages with 4 figures, all uuencoded and gzippe
Jet Production via Strongly-Interacting Color-Singlet Exchange in Collisions
A study of the particle multiplicity between jets with large rapidity
separation has been performed using the D{\O}detector at the Fermilab Tevatron
Collider operating at TeV. A significant excess of
low-multiplicity events is observed above the expectation for color-exchange
processes. The measured fractional excess is , which is consistent with a strongly-interacting
color-singlet (colorless) exchange process and cannot be explained by
electroweak exchange alone. A lower limit of 0.80% (95% C.L.) is obtained on
the fraction of dijet events with color-singlet exchange, independent of the
rapidity gap survival probability.Comment: 15 pages (REVTeX), 3 PS figs (uuencoded/tar compressed, epsf.sty)
Complete postscript available at http://d0sgi0.fnal.gov/d0pubs/journals.html
Submitted to Physical Review Letter
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