175 research outputs found
Selectivity, market timing and the morningstar star-rating system
This paper evaluates the Morningstar mutual fund ranking system. We find that indeed higher Morningstar ratings are associated with higher returns on the portfolios including respectively five-, four-, three-, two- and one-star funds only (STAR5 to STAR1). We then perform an unconditional and conditional portfolio performance evaluation. In both cases the evidence suggests that the better performance of the STAR3, STAR4 and STAR5 categories reflects superior stock selection rather than market timing abilities. Overall, the implication for the Morningstar ranking system is that this is most effective in identifying the worst-performing funds (STAR1 or STAR2) rather than the best-performing ones
Isotopic variation of parity violation in atomic ytterbium
We report on measurements of atomic parity violation, made on a chain of
ytterbium isotopes with mass numbers A=170, 172, 174, and 176. In the
experiment, we optically excite the 6s2 1S0 -> 5d6s 3D1 transition in a region
of crossed electric and magnetic fields, and observe the interference between
the Stark- and weak-interaction-induced transition amplitudes, by making field
reversals that change the handedness of the coordinate system. This allows us
to determine the ratio of the weak-interaction-induced electric-dipole (E1)
transition moment and the Stark-induced E1 moment. Our measurements, which are
at the 0.5% level of accuracy for three of the four isotopes measured, allow a
definitive observation of the isotopic variation of the weak-interaction
effects in an atom, which is found to be consistent with the prediction of the
Standard Model. In addition, our measurements provide information about an
additional Z' boson.Comment: 19 pages, 4 figures, 2 table
Protective vascular coagulation in response to bacterial infection of the kidney is regulated by bacterial lipid A and host CD147
Bacterial infection of the kidney leads to a rapid cascade of host protective responses, many of which are still poorly understood. We have previously shown that following kidney infection with uropathogenicEscherichia coli (UPEC), vascular coagulation is quickly initiated in local perivascular capillaries that protects the host from progressing from a local infection to systemic sepsis. The signaling mechanisms behind this response have not however been described. In this study, we use a number ofin vitro andin vivo techniques, including intravital microscopy, to identify two previously unrecognized components influencing this protective coagulation response. The acylation state of the Lipid A of UPEC lipopolysaccharide (LPS) is shown to alter the kinetics of local coagulation onsetin vivo. We also identify epithelial CD147 as a potential host factor influencing infection-mediated coagulation. CD147 is expressed by renal proximal epithelial cells infected with UPEC, contingent to bacterial expression of the α-hemolysin toxin. The epithelial CD147 subsequently can activate tissue factor on endothelial cells, a primary step in the coagulation cascade. This study emphasizes the rapid, multifaceted response of the kidney tissue to bacterial infection and the interplay between host and pathogen during the early hours of renal infection
Photoconductance Quantization in a Single-Photon Detector
We have made a single-photon detector that relies on photoconductive gain in
a narrow electron channel in an AlGaAs/GaAs 2-dimensional electron gas. Given
that the electron channel is 1-dimensional, the photo-induced conductance has
plateaus at multiples of the quantum conductance 2e/h. Super-imposed on
these broad conductance plateaus are many sharp, small, conductance steps
associated with single-photon absorption events that produce individual
photo-carriers. This type of photoconductive detector could measure a single
photon, while safely storing and protecting the spin degree of freedom of its
photo-carrier. This function is valuable for a quantum repeater that would
allow very long distance teleportation of quantum information.Comment: 4 pages, 4 figure
On the implementation of a recently proposed dosimetric formalism to a robotic radiosurgery system
The aim of this work is to implement a recently proposed dosimetric formalism for nonstandard fields to the calibration and small field output factor measurement of a robotic stereotactic radiosurgery system
ASCR/HEP Exascale Requirements Review Report
This draft report summarizes and details the findings, results, and
recommendations derived from the ASCR/HEP Exascale Requirements Review meeting
held in June, 2015. The main conclusions are as follows. 1) Larger, more
capable computing and data facilities are needed to support HEP science goals
in all three frontiers: Energy, Intensity, and Cosmic. The expected scale of
the demand at the 2025 timescale is at least two orders of magnitude -- and in
some cases greater -- than that available currently. 2) The growth rate of data
produced by simulations is overwhelming the current ability, of both facilities
and researchers, to store and analyze it. Additional resources and new
techniques for data analysis are urgently needed. 3) Data rates and volumes
from HEP experimental facilities are also straining the ability to store and
analyze large and complex data volumes. Appropriately configured
leadership-class facilities can play a transformational role in enabling
scientific discovery from these datasets. 4) A close integration of HPC
simulation and data analysis will aid greatly in interpreting results from HEP
experiments. Such an integration will minimize data movement and facilitate
interdependent workflows. 5) Long-range planning between HEP and ASCR will be
required to meet HEP's research needs. To best use ASCR HPC resources the
experimental HEP program needs a) an established long-term plan for access to
ASCR computational and data resources, b) an ability to map workflows onto HPC
resources, c) the ability for ASCR facilities to accommodate workflows run by
collaborations that can have thousands of individual members, d) to transition
codes to the next-generation HPC platforms that will be available at ASCR
facilities, e) to build up and train a workforce capable of developing and
using simulations and analysis to support HEP scientific research on
next-generation systems.Comment: 77 pages, 13 Figures; draft report, subject to further revisio
Methodology for integrated socio-economic assessment of offshore platforms : towards facilitation of the implementation of the marine strategy framework directive
In this paper a Methodology for Integrated Socio-Economic Assessment (MISEA) of the viability and sustainability of different designs of Multi-Use Offshore Platforms (MUOPs) is presented. MUOPs are designed for multi-use of ocean space for energy extraction (wind power production and wave energy), aquaculture and transport maritime services. The developed methodology allows identification, valuation and assessment of: the potential range of impacts of a number of feasible designs of MUOP investments, and the likely responses of those impacted by the investment project. This methodology provides decision-makers with a valuable decision tool to assess whether a MUOP project increases the overall social welfare and hence should be undertaken, under alternative specifications regarding its design, the discount rate and the stream of net benefits, if a Cost-Benefit Analysis (CBA) is to be followed or sensitivity analysis of selected criteria in a Multi-Criteria Decision Analysis (MCDA) framework. Such a methodology is also crucial for facilitating of the implementation of the Marine Strategy Framework Directive (MSFD adopted in June 2008) that aims to achieve good environmental status of the EU's marine waters by 2020 and to protect the resource base upon which marine-related economic and social activities depend. According to the MSFD each member state must draw up a program of cost-effective measures, while prior to any new measure an impact assessment which contains a detailed cost-benefit analysis of the proposed measures is required
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