27,902 research outputs found
Reading policies for joins: An asymptotic analysis
Suppose that observations are made from the distribution
and from the distribution . Associate with each pair,
from and from , a nonnegative score .
An optimal reading policy is one that yields a sequence that maximizes
, the expected sum of the observed scores,
uniformly in . The alternating policy, which switches between the two
sources, is the optimal nonadaptive policy. In contrast, the greedy policy,
which chooses its source to maximize the expected gain on the next step, is
shown to be the optimal policy. Asymptotics are provided for the case where the
and distributions are discrete and according as or not (i.e., the observations match). Specifically, an
invariance result is proved which guarantees that for a wide class of policies,
including the alternating and the greedy, the variable M(n) obeys the same CLT
and LIL. A more delicate analysis of the sequence and the
sample paths of M(n), for both alternating and greedy, reveals the slender
sense in which the latter policy is asymptotically superior to the former, as
well as a sense of equivalence of the two and robustness of the former.Comment: Published at http://dx.doi.org/10.1214/105051606000000646 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
Collective intellectual property rights for the development of creative tourist districts: an exploration
In this paper the institution of Collective Intellectual Property Rights (CIPR) is proposed as a regulatory tool for the development of Creative Tourist Districts based on local knowledge and trust, described as a superior organisational model of destinations to alternative models founded on individual property. As there are various types and contexts of applications of CIPR, as well as different development objectives to be achieved, the paper designs a strategy to maximise the expected impacts from case to case. It then proposes âarea labelsâ, based on a combination of controls on quality and delimitation of areas of validity of the right, as the best instrument to foster a strategic orientation to quality across the local tourism industry.
The BARISTA: A model for bid arrivals in online auctions
The arrival process of bidders and bids in online auctions is important for
studying and modeling supply and demand in the online marketplace. A popular
assumption in the online auction literature is that a Poisson bidder arrival
process is a reasonable approximation. This approximation underlies theoretical
derivations, statistical models and simulations used in field studies. However,
when it comes to the bid arrivals, empirical research has shown that the
process is far from Poisson, with early bidding and last-moment bids taking
place. An additional feature that has been reported by various authors is an
apparent self-similarity in the bid arrival process. Despite the wide evidence
for the changing bidding intensities and the self-similarity, there has been no
rigorous attempt at developing a model that adequately approximates bid
arrivals and accounts for these features. The goal of this paper is to
introduce a family of distributions that well-approximate the bid time
distribution in hard-close auctions. We call this the BARISTA process (Bid
ARrivals In STAges) because of its ability to generate different intensities at
different stages. We describe the properties of this model, show how to
simulate bid arrivals from it, and how to use it for estimation and inference.
We illustrate its power and usefulness by fitting simulated and real data from
eBay.com. Finally, we show how a Poisson bidder arrival process relates to a
BARISTA bid arrival process.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS117 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Entanglement entropy and D1-D5 geometries
http://dx.doi.org/10.1103/PhysRevD.90.066004Giusto, Stefano, and Rodolfo Russo. "Entanglement Entropy and D1-D5 geometries." Physical Review D 90.6 (2014): 066004
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Faculty and student feedback of synchronous distance education in a multi-university learning consortium
The Texas Learning Consortium (TLC) began as a partnership between the foreign language departments at 5 small, private, liberal arts universities, where each specializes in a small number of different world languages to increase the course offerings to their students without the expense of adding additional faculty on every campus. Each university offers their language courses to consortium students in a real-time, interactive, distance education format. In Fall 2017, the consortium expanded beyond foreign languages, and the first engineering course, Statics, was offered in this synchronous, distance format. As background, this paper will provide an overview of the technology used in the classrooms and some of the administrative obstacles that were overcome in scheduling, registration and information technology. The paper will also reflect on the impact of this particular technological implementation on various teaching styles in both foreign language and engineering courses, especially compared to other distance engineering education in the literature, with a purpose of analyzing the modelâs suitability for expansion into other engineering courses or a fully accredited consortium based engineering program. Student and faculty satisfaction surveys will additionally provide insight as to whether this distance format is the right fit for campuses used to high-touch learning environments.Cockrell School of Engineerin
Density Functional Calculations On First-Row Transition Metals
The excitation energies and ionization potentials of the atoms in the first
transition series are notoriously difficult to compute accurately. Errors in
calculated excitation energies can range from 1--4 eV at the Hartree-Fock
level, and errors as high as 1.5eV are encountered for ionization energies. In
the current work we present and discuss the results of a systematic study of
the first transition series using a spin-restricted Kohn-Sham
density-functional method with the gradient-corrected functionals of Becke and
Lee, Yang and Parr. Ionization energies are observed to be in good agreement
with experiment, with a mean absolute error of approximately 0.15eV; these
results are comparable to the most accurate calculations to date, the Quadratic
Configuration Interaction (QCISD(T)) calculations of Raghavachari and Trucks.
Excitation energies are calculated with a mean error of approximately 0.5eV,
compared with \sim 1\mbox{eV} for the local density approximation and 0.1eV
for QCISD(T). These gradient-corrected functionals appear to offer an
attractive compromise between accuracy and computational effort.Comment: Journal of Chemical Physics, 29, LA-UR-93-425
Cancer-Associated Thrombosis in Cirrhotic Patients with Hepatocellular Carcinoma.
It is common knowledge that cancer patients are more prone to develop venous thromboembolic complications (VTE). It is therefore not surprising that patients with hepatocellular carcinoma (HCC) present with a significant risk of VTE, with the portal vein being the most frequent site (PVT). However, patients with HCC are peculiar as both cancer and liver cirrhosis are conditions that can perturb the hemostatic balance towards a prothrombotic state. Because HCC-related hypercoagulability is not clarified at all, the aim of the present review is to summarize the currently available knowledge on epidemiology and pathogenesis of non-malignant thrombotic complications in patients with liver cirrhosis and HCC. They are at increased risk to develop both PVT and non-splanchnic VTE, indicating that both local and systemic factors can foster the development of site-specific thrombosis. Recent studies have suggested multiple and often interrelated mechanisms through which HCC can tip the hemostatic balance of liver cirrhosis towards hypercoagulability. Described mechanisms include increased fibrinogen concentration/polymerization, thrombocytosis, and release of tissue factor-expressing extracellular vesicles. Currently, there are no specific guidelines on the use of thromboprophylaxis in this unique population. There is the urgent need of prospective studies assessing which patients have the highest prothrombotic profile and would therefore benefit from early thromboprophylaxis
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