3,725 research outputs found
Twenty Years of Searching for the Higgs Boson: Exclusion at LEP, Discovery at LHC
The 40 years old Standard Model, the theory of particle physics, seems to
describe all experimental data very well. All of its elementary particles were
identified and studied apart from the Higgs boson until 2012. For decades many
experiments were built and operated searching for it, and finally, the two main
experiments of the Large Hadron Collider at CERN, CMS and ATLAS, in 2012
observed a new particle with properties close to those predicted for the Higgs
boson. In this paper we outline the search story: the exclusion of the Higgs
boson at LEP, the Large Electron Positron collider, and its observation at LHCComment: arXiv admin note: substantial text overlap with arXiv:1310.683
Stable sets in one-seller assignment games
We consider von Neumann -- Morgenstern stable sets in assignment games with one seller and many buyers. We prove that a set of imputations is a stable set if and only if it is the graph of a certain type of continuous and monotone function. This characterization enables us to interpret the standards of behavior encompassed by the various stable sets as possible outcomes of well-known auction procedures when groups of buyers may form bidder rings. We also show that the union of all stable sets can be described as the union of convex polytopes all of whose vertices are marginal
contribution payoff vectors. Consequently, each stable set is contained in the Weber set. The Shapley value, however, typically falls outside the union of all stable sets
Analytic approximation of energy resolution in cascaded gaseous detectors
An approximate formula has been derived for gain fluctuations in cascaded
gaseous detectors such as GEM-s, based on the assumption that the charge
collection, avalanche formation and extraction steps are independent cascaded
processes. In order to test the approximation experimentally, a setup involving
a standard GEM layer has been constructed to measure the energy resolution for
5.9 keV gamma particles. The formula reasonably traces both the charge
collection as well as the extraction process dependence of the energy
resolution. Such analytic approximation for gain fluctuations can be applied to
multi-GEM detectors where it aids the interpretation of measurements as well as
simulations.Comment: 6 pages, 10 figures, submitted to Adv. in High Energy Phy
Unraveling the behavior of the individual ionic activity coefficients on the basis of the balance of ion-ion and ion-water interactions
We investigate the individual activity coefficients of pure 1:1 and 2:1
electrolytes using our theory that is based on the competition of ion-ion (II)
and ion-water (IW) interactions (Vincze et al., J. Chem. Phys. 133, 154507,
2010). The II term is computed from Grand Canonical Monte Carlo simulations on
the basis of the implicit solvent model of electrolytes using hard sphere ions
with Pauling radii. The IW term is computed on the basis of Born's treatment of
solvation using experimental hydration free energies. The two terms are coupled
through the concentration-dependent dielectric constant of the electrolyte.
With this approach we are able to reproduce the nonmonotonic concentration
dependence of the mean activity coefficient of pure electrolytes qualitatively
without using adjustable parameters. In this paper, we show that the theory can
provide valuable insight into the behavior of individual activity coefficients
too. We compare our theoretical predictions against experimental data measured
by electrochemical cells containing ion-specific electrodes. As in the case of
the mean activity coefficients, we find good agreement for 2:1 electrolytes,
while the accuracy of our model is worse for 1:1 systems. This deviation in
accuracy is explained by the fact that the two competing terms (II and IW) are
much larger in the 2:1 case so errors in the two separate terms have less
effects. The difference of the excess chemical potentials of cations and anions
(the ratio of activity coefficients) is determined by asymmetries in the
properties of the two ions: charge, radius, and hydration free energies.Comment: 32 pages, 8 figures, 1 TOC figur
Galaxy shape measurement with convolutional neural networks
We present our results from training and evaluating a convolutional neural
network (CNN) to predict galaxy shapes from wide-field survey images of the
first data release of the Dark Energy Survey (DES DR1). We use conventional
shape measurements as ground truth from an overlapping, deeper survey with less
sky coverage, the Canada-France Hawaii Telescope Lensing Survey (CFHTLenS). We
demonstrate that CNN predictions from single band DES images reproduce the
results of CFHTLenS at bright magnitudes and show higher correlation with
CFHTLenS at fainter magnitudes than maximum likelihood model fitting estimates
in the DES Y1 im3shape catalogue. Prediction of shape parameters with a CNN is
also extremely fast, it takes only 0.2 milliseconds per galaxy, improving more
than 4 orders of magnitudes over forward model fitting. The CNN can also
accurately predict shapes when using multiple images of the same galaxy, even
in different color bands, with no additional computational overhead. The CNN is
again more precise for faint objects, and the advantage of the CNN is more
pronounced for blue galaxies than red ones when compared to the DES Y1
metacalibration catalogue, which fits a single Gaussian profile using riz band
images. We demonstrate that CNN shape predictions within the metacalibration
self-calibrating framework yield shear estimates with negligible multiplicative
bias, , and no significant PSF leakage. Our proposed setup is
applicable to current and next generation weak lensing surveys where higher
quality ground truth shapes can be measured in dedicated deep fields
The effect of the charge pattern on the applicability of a nanopore as a sensor
We investigate a model nanopore sensor that is able to detect analyte ions
that are present in the electrolyte solution in very small concentrations. The
nanopore selectively binds the analyte ions with which the local concentrations
of the ions of the background electrolyte (KCl), and, thus, the ionic current
flowing through the pore is changed. Analyte concentration can be determined
from calibration curves. In our previous study (M\'{a}dai et al. J. Chem.
Phys., 147(24):244702, 2017.), we proposed a symmetric model (surface charge is
negative all along the pore). The mechanism of sensing was a competition
between K and positive analyte ions, so increasing analyte concentration
decreased K current. Here we allow asymmetric charge patterns on the pore
wall (positive/negative/neutral along the pore), thus, gaining an additional
device function, rectification, resulting in a dual responsive device. We find
that a bipolar nanopore is an efficient geometry with Cl ions being the
main charge carriers. The mechanism of sensing is that more positive analyte
ions attract more Cl ions into the pore thus increasing the current. Also
they make the pore less asymmetric and, thus, decrease rectification. We use a
hybrid computer simulation method, where a generalization of the grand
canonical Monte Carlo method to non-equilibrium (Local Equilibrium Monte Carlo)
is coupled to the Nernst-Planck equation with which the flux is computed
An improved cosmological parameter inference scheme motivated by deep learning
Dark matter cannot be observed directly, but its weak gravitational lensing
slightly distorts the apparent shapes of background galaxies, making weak
lensing one of the most promising probes of cosmology. Several observational
studies have measured the effect, and there are currently running, and planned
efforts to provide even larger, and higher resolution weak lensing maps. Due to
nonlinearities on small scales, the traditional analysis with two-point
statistics does not fully capture all the underlying information. Multiple
inference methods were proposed to extract more details based on higher order
statistics, peak statistics, Minkowski functionals and recently convolutional
neural networks (CNN). Here we present an improved convolutional neural network
that gives significantly better estimates of and
cosmological parameters from simulated convergence maps than the state of art
methods and also is free of systematic bias. We show that the network exploits
information in the gradients around peaks, and with this insight, we construct
a new, easy-to-understand, and robust peak counting algorithm based on the
'steepness' of peaks, instead of their heights. The proposed scheme is even
more accurate than the neural network on high-resolution noiseless maps. With
shape noise and lower resolution its relative advantage deteriorates, but it
remains more accurate than peak counting
Establishing an Internet Based Paediatric Cancer Registration and Communication System for the Hungarian Paediatric Oncology Network
Cancer registration has developed in Europe over the last 50 years, and in the last decade intensive joint activities between the European Cancer Registries, in response to the need of pan-European harmonization of registration practices, have taken place. The Hungarian Paediatric Cancer Registry has been functioning as the database of the Hungarian Paediatric Oncology Network since 1971, aiming to follow the incidence and the treatment efficacy of malignant diseases.The goals of this globally unique open source information system are the following: 1) to raise the quality of the registration system to the European level by developing an Internet-based registration and communication system, modernizing the database, establishing automatic statistical analyses and adding an Internet website, 2) to support clinical epidemiological studies that we conduct with international collaborators on detailed analyses of the characteristics of patients and their diseases, evaluation of new diagnostic and therapeutic methods, prevention programs, and long-term quality of life and side effects.The benefits of the development of the Internet-based registration and communication system are as follows: a) introduction of an Internet-based case reporting system, b) modernization of the registry database according to international recommendations, c) automatic statistical summaries, encrypted mail systems, document repository, d) application of data security and privacy standards, e) establishment of a website and compilation of educational materials.The overall objective of this scientific project is to contribute towards the improvement of cancer prevention and cancer care for the benefit of the public in general and of cancer patients in particular
- …