70,368 research outputs found
Short lists with short programs in short time - a short proof
Bauwens, Mahklin, Vereshchagin and Zimand [ECCC TR13-007] and Teutsch
[arxiv:1212.6104] have shown that given a string x it is possible to construct
in polynomial time a list containing a short description of it. We simplify
their technique and present a shorter proof of this result
Concept Validation for Selective Heating and Press Hardening of Automotive Safety Components with Tailored Properties
© (2014) Trans Tech Publications, Switzerland.A new strategy termed selective heating and press hardening, for hot stamping of boron steel parts with tailored properties is proposed in this paper. Feasibility studies were carried out through a specially designed experimental programme. The main aim was to validate the strategy and demonstrate its potential for structural optimisation. In the work, a lab-scale demonstrator part was designed, and relevant manufacturing and property-assessment processes were defined. A heating technique and selective-heating rigs were designed to enable certain microstructural distributions in blanks to be obtained. A hot stamping tool set was designed for forming and quenching the parts. Demonstrator parts of full martensite phase, full initial phase, and differentially graded microstructures have been formed with high dimensional quality. Hardness testing and three point bending tests were conducted to assess the microstructure distribution and load bearing performance of the as-formed parts, respectively. The feasibility of the concept has been validated by the testing results
A Complete Year of User Retrieval Sessions in a Social Sciences Academic Search Engine
In this paper, we present an open data set extracted from the transaction log
of the social sciences academic search engine sowiport. The data set includes a
filtered set of 484,449 retrieval sessions which have been carried out by
sowiport users in the period from April 2014 to April 2015. We propose a
description of interactions performed by the academic search engine users that
can be used in different applications such as result ranking improvement, user
modeling, query reformulation analysis, search pattern recognition.Comment: 6 pages, 2 figures, accepted short paper at the 21st International
Conference on Theory and Practice of Digital Libraries (TPDL 2017
Mapping Functions in Health-Related Quality of Life: Mapping From Two Cancer-Specific Health-Related Quality-of-Life Instruments to EQ-5D-3L.
BACKGROUND: Clinical trials in cancer frequently include cancer-specific measures of health but not preference-based measures such as the EQ-5D that are suitable for economic evaluation. Mapping functions have been developed to predict EQ-5D values from these measures, but there is considerable uncertainty about the most appropriate model to use, and many existing models are poor at predicting EQ-5D values. This study aims to investigate a range of potential models to develop mapping functions from 2 widely used cancer-specific measures (FACT-G and EORTC-QLQ-C30) and to identify the best model. METHODS: Mapping models are fitted to predict EQ-5D-3L values using ordinary least squares (OLS), tobit, 2-part models, splining, and to EQ-5D item-level responses using response mapping from the FACT-G and QLQ-C30. A variety of model specifications are estimated. Model performance and predictive ability are compared. Analysis is based on 530 patients with various cancers for the FACT-G and 771 patients with multiple myeloma, breast cancer, and lung cancer for the QLQ-C30. RESULTS: For FACT-G, OLS models most accurately predict mean EQ-5D values with the best predicting model using FACT-G items with similar results using tobit. Response mapping has low predictive ability. In contrast, for the QLQ-C30, response mapping has the most accurate predictions using QLQ-C30 dimensions. The QLQ-C30 has better predicted EQ-5D values across the range of possible values; however, few respondents in the FACT-G data set have low EQ-5D values, which reduces the accuracy at the severe end. CONCLUSIONS: OLS and tobit mapping functions perform well for both instruments. Response mapping gives the best model predictions for QLQ-C30. The generalizability of the FACT-G mapping function is limited to populations in moderate to good health
radiative decays to light quark jets and color octet mechanism
We study radiative decays of to light quark jets in
nonrelativistic QCD by taking both the color singlet and color octet
operators into consideration. The cut for quark jet energy and cut for the
angle between two quark jets are introduced. The sensitivity to the soft and
collinear singularities in the loop integrals are greatly reduced by these
cuts. With the jet energy cut of about 1 GeV, and the jet angle cut of about
, the branching ratio for is found to be
from color singlet contributions. The color octet
contributions could be much larger than that of color singlet, depending on the
estimate of the color octet matrix elements. This process may provide a new
test for the color octet mechanism in nonrelativistic QCD.Comment: journal version; a few references adde
Hardness of approximation for quantum problems
The polynomial hierarchy plays a central role in classical complexity theory.
Here, we define a quantum generalization of the polynomial hierarchy, and
initiate its study. We show that not only are there natural complete problems
for the second level of this quantum hierarchy, but that these problems are in
fact hard to approximate. Using these techniques, we also obtain hardness of
approximation for the class QCMA. Our approach is based on the use of
dispersers, and is inspired by the classical results of Umans regarding
hardness of approximation for the second level of the classical polynomial
hierarchy [Umans, FOCS 1999]. The problems for which we prove hardness of
approximation for include, among others, a quantum version of the Succinct Set
Cover problem, and a variant of the local Hamiltonian problem with hybrid
classical-quantum ground states.Comment: 21 pages, 1 figure, extended abstract appeared in Proceedings of the
39th International Colloquium on Automata, Languages and Programming (ICALP),
pages 387-398, Springer, 201
BORIS/CTCFL is an RNA-binding protein that associates with polysomes
© 2013 Ogunkolade et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the
Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited
Fermion masses in the economical 3-3-1 model
We show that, in frameworks of the economical 3-3-1 model, all fermions get
masses. At the tree level, one up-quark and two down-quarks are massless, but
the one-loop corrections give all quarks the consistent masses. This conclusion
is in contradiction to the previous analysis in which, the third scalar triplet
has been introduced. This result is based on the key properties of the model:
First, there are three quite different scales of vacuum expectation values:
\om \sim {\cal O}(1) \mathrm{TeV}, v \approx 246 \mathrm{GeV} and . Second, there exist two types of Yukawa couplings
with different strengths: the lepton-number conserving couplings 's and the
lepton-number violating ones 's satisfying the condition in which the second
are much smaller than the first ones: .
With the acceptable set of parameters, numerical evaluation shows that in
this model, masses of the exotic quarks also have different scales, namely, the
exotic quark () gains mass GeV, while the
D_\al exotic quarks (q_{D_\al} = -1/3) have masses in the TeV scale:
m_{D_\al} \in 10 \div 80 TeV.Comment: 20 pages, 8 figure
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