pinecone/core-2020-05-10-deduplication huggingface dataset:
Analysis of events with b-jets and a pair of leptons of the same charge in pp collisions at root s=8 TeV with the ATLAS detector

An analysis is presented of events containing jets including at least one b-tagged jet, sizeable missing transverse momentum, and at least two leptons including a pair of the same electric charge, with the scalar sum of the jet and lepton transverse momenta being large. A data sample with an integrated luminosity of 20.3 fb(-1) of pp collisions at root s = 8 TeV recorded by the ATLAS detector at the Large Hadron Collider is used. Standard Model processes rarely produce these final states, but there are several models of physics beyond the Standard Model that predict an enhanced rate of production of such events; the ones considered here are production of vector-like quarks, enhanced fourtop-quark production, pair production of chiral b '-quarks, and production of two positively charged top quarks. Eleven signal regions are defined; subsets of these regions are combined when searching for each class of models. In the three signal regions primarily sensitive to positively charged top quark pair production, the data yield is consistent with the background expectation. There are more data events than expected from background in the set of eight signal regions defined for searching for vector-like quarks and chiral b ' quarks, but the significance of the discrepancy is less than two standard deviations. The discrepancy reaches 2.5 standard deviations in the set of five signal regions defined for searching for four-top-quark production. The results are used to set 95% CL limits on various models.<p>ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1007/JHEP10(2015)150</p><p></p
A new mimetic scheme for the acoustic wave equation

A new mimetic finite difference scheme for solving the acoustic wave equation is presented. It combines a novel second order tensor mimetic discretizations in space and a leapfrog approximation in time to produce an explicit multidimensional scheme. Convergence analysis of the new scheme on a staggered grid shows that it can take larger time steps than standard finite difference schemes based on ghost points formulation. A set of numerical test problems gives evidence of the versatility of the new mimetic scheme for handling general boundary conditions.Peer ReviewedPreprin
Constraints on the multi-TeV particle population in the Coma galaxy cluster with HESS observations

Aims. Galaxy clusters are key targets in the search for ultra high energy particle accelerators. The Coma cluster represents one of the best candidates for such a search owing to its high mass, proximity, and the established non-thermal radio emission centred on the cluster core.\ud
Methods. The HESS (High Energy Stereoscopic System) telescopes observed Coma for ~8 h in a search for $\gamma$-ray emission at energies >1 TeV. The large 3.5° FWHM field of view of HESS is ideal for viewing a range of targets at various sizes including the Coma cluster core, the radio-relic (1253+275) and merger/infall (NGC 4839) regions to the southwest, and features greater than $1^\circ$ away.\ud
Results. No evidence for point-like nor extended TeV $\gamma$-ray emission was found and upper limits to the TeV flux F(E) for E>1, >5, and >10 TeV were set for the Coma core and other regions. Converting these limits to an energy flux E2F(E) the lowest or most constraining is the E>5 TeV upper limit for the Coma core (0.2° radius) at ~8% Crab flux units or ${\sim}10^{-13}$ ph cm-2 s-1.\ud
Conclusions. The upper limits for the Coma core were compared with a prediction for the $\gamma$-ray emission from proton-proton interactions, the level of which ultimately scales with the mass of the Coma cluster. A direct constraint using our most stringent limit for E>5 TeV, on the total energy content in non-thermal protons with injection energy spectrum ${\propto} E^{-2.1}$ and spatial distribution following the thermal gas in the cluster, is found to be ~0.2 times the thermal energy, or ${\sim} 10^{62}$ erg. The E>5 TeV $\gamma$-ray threshold in this case corresponds to cosmic-ray proton energies $\ga$50 TeV. Our upper limits rule out the most optimistic theoretical models for gamma ray emission from clusters and complement radio observations which constrain the cosmic ray content in clusters at significantly lower proton energies, subject to assumptions on the magnetic field strength.Peer-reviewedPublisher Version10054
Evolution of field line helicity during magnetic reconnection.

We investigate the evolution of field line helicity for magnetic fields that connect two boundaries without null points, with emphasis on localized finite-B magnetic reconnection. Total (relative) magnetic helicity is already recognized as an important topological constraint on magnetohydrodynamic processes. Field line helicity offers further advantages because it preserves all topological information and can distinguish between different magnetic fields with the same total helicity. Magnetic reconnection changes field connectivity and field line helicity reflects these changes; the goal of this paper is to characterize that evolution. We start by deriving the evolution equation for field line helicity and examining its terms, also obtaining a simplified form for cases where dynamics are localized within the domain. The main result, which we support using kinematic examples, is that during localized reconnection in a complex magnetic field, the evolution of field line helicity is dominated by a work-like term that is evaluated at the field line endpoints, namely, the scalar product of the generalized field line velocity and the vector potential. Furthermore, the flux integral of this term over certain areas is very small compared to the integral of the unsigned quantity, which indicates that changes of field line helicity happen in a well-organized pairwise manner. It follows that reconnection is very efficient at redistributing helicity in complex magnetic fields despite having little effect on the total helicity
A Quantatiitive Study of Texture Features across Different Window Sizes in Prostate T2-weighted MRI

This study aims to investigate the effects of window size on the performance of prostate cancer CAD and to identify discriminant texture descriptors in prostate T2-W MRI. For this purpose we extracted 215 texture features from 418 T2-W MRI images and extracted them using 9 different window sizes (3 ? 3 to 19 ? 19). The Bayesian Network and Random Forest classifiers were employed to perform the classification. Experimental results suggest that using window size of 9 ? 9 and 11 ? 11 produced Az > 89%. Also, this study suggests a set of best texture features based on our experimental results.publishersversionpublishersversionPeer reviewe
Achieving both high selectivity and current density for CO2 reduction to formate on nanoporous tin foam electrocatalysts

Currently, low catalytic activity, selectivity and stability are the biggest challenges which restrict the large scale applications of CO2  electrochemical reduction. Formic acid, one of the highest value-added products from electrochemical reduction of CO2, has gathered much interest. Here, we develop nanoporous tin foam catalysts which exhibit significantly high selectivity and faster production rate to formate. In a 0.1 M NaHCO3 solution, the maximum Faradaic efficiency for formate production reaches above 90% with a current density over 23 mA cm-2 , which are among the highest reported value to date under ambient conditions. The improved production rate can be attributed to the high surface area and porous structure. Moreover, the electrocatalysts are quite stable, namely, the Faradaic efficiency remains unchanged during 16 hour electrolysis. This is a promising technology to convert CO2 into useful hydrocarbons
3D electron density distributions in the solar corona during solar
  minima: assessment for more realistic solar wind modeling

Knowledge of the electron density distribution in the solar corona put
constraints on the magnetic field configurations for coronal modeling and on
initial conditions for solar wind modeling. We work with polarized
SOHO/LASCO-C2 images from the last two recent minima of solar activity
(1996-1997 and 2008-2010), devoid of coronal mass ejections. The goals are to
derive the 4D electron density distributions in the corona by applying a newly
developed time-dependent tomographic reconstruction method and to compare the
results between the two solar minima and with two magnetohydrodynamic models.
First, we confirm that the values of the density distribution in thermodynamic
models are more realistic than in polytropic ones. The tomography provides more
accurate distributions in the polar regions, and we find that the density in
tomographic and thermodynamic solutions varies with the solar cycle in both
polar and equatorial regions. Second, we find that the highest-density
structures do not always correspond to the predicted large-scale heliospheric
current sheet or its helmet streamer but can follow the locations of
pseudo-streamers. We deduce that tomography offers reliable density
distributions in the corona, reproducing the slow time evolution of coronal
structures, without prior knowledge of the coronal magnetic field over a full
rotation. Finally, we suggest that the highest-density structures show a
differential rotation well above the surface depending on how they are
magnetically connected to the surface. Such valuable information on the
rotation of large-scale structures could help to connect the sources of the
solar wind to their in situ counterparts in future missions such as Solar
Orbiter and Solar Probe Plus.Comment: 23 pages, 9 figure
Beyond $\Lambda$CDM: Problems, solutions, and the road ahead

Despite its continued observational successes, there is a persistent (and
growing) interest in extending cosmology beyond the standard model,
$\Lambda$CDM. This is motivated by a range of apparently serious theoretical
issues, involving such questions as the cosmological constant problem, the
particle nature of dark matter, the validity of general relativity on large
scales, the existence of anomalies in the CMB and on small scales, and the
predictivity and testability of the inflationary paradigm. In this paper, we
summarize the current status of $\Lambda$CDM as a physical theory, and review
investigations into possible alternatives along a number of different lines,
with a particular focus on highlighting the most promising directions. While
the fundamental problems are proving reluctant to yield, the study of
alternative cosmologies has led to considerable progress, with much more to
come if hopes about forthcoming high-precision observations and new theoretical
ideas are fulfilled.Comment: 99 pages, 8 figures. Version published in Physics of the Dark
  Univers
String completion of an $\mathrm{SU(3)_c \otimes SU(3)_L \otimes
  U(1)_X}$ electroweak model

The extended electroweak $\mathrm{SU(3)_c \otimes SU(3)_L \otimes U(1)_X}$
symmetry framework "explaining" the number of fermion families is revisited.
While $331$-based schemes can not easily be unified within the conventional
field theory sense, we show how to do it within an approach based on D-branes
and (un)oriented open strings, on Calabi-Yau singularities. We show how the
theory can be UV-completed in a quiver setup, free of gauge and string
anomalies. Lepton and baryon numbers are perturbatively conserved, so neutrinos
are Dirac-type, and their lightness results from a novel TeV scale seesaw
mechanism. Dynamical violation of baryon number by exotic instantons could
induce neutron-antineutron oscillations, with proton decay and other dangerous
R-parity violating processes strictly forbidden.Comment: 12 pages, 2 figures, published versio
A Rotation/Magnetism Analogy for the Quark-Gluon Plasma

In peripheral heavy ion collisions, the Quark-Gluon Plasma that may be formed
often has a large angular momentum per unit energy. This angular momentum may
take the form of (local) rotation. In many physical systems, rotation can have
effects analogous to those produced by a magnetic field; thus, there is a risk
that the effects of local rotation in the QGP might be mistaken for those of
the large genuine magnetic fields which are also known to arise in these
systems. Here we use the gauge-gravity duality to investigate this, and we find
indeed that, with realistic parameter values, local rotation has effects on the
QGP (at high values of the baryonic chemical potential) which are not only of
the same kind as those produced by magnetic fields, but which can in fact be
substantially larger. Furthermore, the combined effect of rotation and
magnetism is to change the shape of the main quark matter phase transition line
in an interesting way, reducing the magnitude of its curvature; again, local
rotation contributes to this phenomenon at least as strongly as magnetism.Comment: Various clarifications, included brief discussion of finite size
  effects, 21 pages, 4 figures; version to appear in Nuclear Physics
Multiplication of the depth of detectability using gamma 11n arrays

The depth from which one can get information has always been a crucial parameter in the geophysical exploration. This paper deals with the depth of detectability (DD) of 2D electric resistivity tomography configurations. DD is the maximal depth from which a given model body is detectable in the presence of a given noise level. Based on previous DD calculations for conventional electrode arrays it is shown in this paper that there is a nearly linear relation between the maximum value of their parameter-sensitivity (PS) maps and their DD values. Studying the PS maps of other arrays, as well, we found that many of them have higher PSmax values than those of the conventional arrays. These so-called arrays are therefore expected to have larger DD values, too. The performed DD-calculations have confirmed this expectation. gamma 11n In arrays are linear geoelectric arrays where refers to the CPCP order of the current (C) and potential (P) electrodes whilst the subscript numbers refer to the distance of the neighbouring electrodes. In case of the studied prism and dyke models the gamma 11n arrays - if n is larger or equal to 2 - consistently produced higher DD-values than the best conventional arrays. The DD value of these arrays can be even 2-3 times larger than that of the best conventional array value. Such an increase in the DD value is especially useful if the available place for measurements is limited, e.g. due to infrastructural conditions. Anomalies in large depth, for example, which are not seen by traditionally used arrays, may become detectable using gamma 11n arrays as it was verified also by numerical studies. These arrays require moreover less measurement than most conventional arrays resulting in shorter measuring time. (C) 2014 Elsevier B.V. All rights reserved
The relationship between CSF tau markers, hippocampal volume and delayed primacy performance in cognitively intact elderly individuals.

"Background\ud
Primacy performance in recall has been shown to predict cognitive decline in cognitively intact elderly and conversion from mild cognitive impairment to Alzheimer's disease (AD). Delayed primacy performance, but not delayed nonprimacy performance, has been shown to be associated with hippocampal volume in cognitively intact older individuals. Because presence of neurofibrillary tangles is an early sign of AD-related pathology, we set out to test whether cerebrospinal fluid (CSF) levels of tau had an effect on delayed primacy performance, while controlling for hippocampal volume and CSF amyloid-β 1-42 levels.\ud
Methods\ud
Forty-seven individuals, aged 60 years or older and cognitively intact, underwent a multisession study including lumbar puncture, a magnetic resonance imaging (MRI) scan of the head, and memory testing.\ud
Results\ud
Our regression analyses show that CSF levels of hyperphosphorylated (P) tau are only associated with reduced delayed primacy performance when hippocampal volumes are smaller.\ud
Conclusion\ud
Our findings suggest that hippocampal size may play a protective role against the negative effects of P tau on memory.
Centrality and rapidity dependence of inclusive jet production in root sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Çetin, Serkant Ali (Dogus Author)Measurements of the centrality and rapidity dependence of inclusive jet production in sNN=5.02 TeV proton-lead (p+Pb) collisions and the jet cross-section in s=2.76 TeV proton-proton collisions are presented. These quantities are measured in datasets corresponding to an integrated luminosity of 27.8 nb-1 and 4.0 pb-1, respectively, recorded with the ATLAS detector at the Large Hadron Collider in 2013. The p+Pb collision centrality was characterised using the total transverse energy measured in the pseudorapidity interval -4.9<η<-3.2 in the direction of the lead beam. Results are presented for the double-differential per-collision yields as a function of jet rapidity and transverse momentum (pT) for minimum-bias and centrality-selected p+Pb collisions, and are compared to the jet rate from the geometric expectation. The total jet yield in minimum-bias events is slightly enhanced above the expectation in a pT-dependent manner but is consistent with the expectation within uncertainties. The ratios of jet spectra from different centrality selections show a strong modification of jet production at all pT at forward rapidities and for large pT at mid-rapidity, which manifests as a suppression of the jet yield in central events and an enhancement in peripheral events. These effects imply that the factorisation between hard and soft processes is violated at an unexpected level in proton-nucleus collisions. Furthermore, the modifications at forward rapidities are found to be a function of the total jet energy only, implying that the violations may have a simple dependence on the hard parton-parton kinematics
Encapsulation and Dynamic Modularity in the Pi-Calculus

International audienceWe describe a process calculus featuring high level constructs for component-oriented programming in a distributed setting. We propose an extension of the higher-order pi-calculus intended to capture several important mechanisms related to component-based programming, such as dynamic update, reconfiguration and code migration. In this paper, we are primarily concerned with the possibility to build a distributed implementation of our calculus. Accordingly, we define a low-level calculus, that describes how the high-level constructs are implemented, as well as details of the data structures manipulated at runtime. We also discuss current and future directions of research in relation to our analysis of component-based programming
TERT promoter mutations are highly recurrent in SHH subgroup medulloblastoma.

Telomerase reverse transcriptase (TERT) promoter mutations were recently shown to drive telomerase activity in various cancer types, including medulloblastoma. However, the clinical and biological implications of TERT mutations in medulloblastoma have not been described. Hence, we sought to describe these mutations and their impact in a subgroup-specific manner. We analyzed the TERT promoter by direct sequencing and genotyping in 466 medulloblastomas. The mutational distributions were determined according to subgroup affiliation, demographics, and clinical, prognostic, and molecular features. Integrated genomics approaches were used to identify specific somatic copy number alterations in TERT promoter-mutated and wild-type tumors. Overall, TERT promoter mutations were identified in 21 % of medulloblastomas. Strikingly, the highest frequencies of TERT mutations were observed in SHH (83 %; 55/66) and WNT (31 %; 4/13) medulloblastomas derived from adult patients. Group 3 and Group 4 harbored  this alteration in <5 % of cases and showed no association with increased patient age. The prognostic implications of these mutations were highly subgroup-specific. TERT mutations identified a subset with good and poor prognosis in SHH and Group 4 tumors, respectively. Monosomy 6 was mostly restricted to WNT tumors without TERT mutations. Hallmark SHH focal copy number aberrations and chromosome 10q deletion were mutually exclusive with TERT mutations within SHH tumors. TERT promoter mutations are the most common recurrent somatic point mutation in medulloblastoma, and are very highly enriched in adult SHH and WNT tumors. TERT mutations define a subset of SHH medulloblastoma with distinct demographics, cytogenetics, and outcomes
Finding vertex-surjective graph homomorphisms

The Surjective Homomorphism problem is to test whether a given graph G called
the guest graph allows a vertex-surjective homomorphism to some other given
graph H called the host graph. The bijective and injective homomorphism
problems can be formulated in terms of spanning subgraphs and subgraphs, and as
such their computational complexity has been extensively studied. What about
the surjective variant? Because this problem is NP-complete in general, we
restrict the guest and the host graph to belong to graph classes G and H,
respectively. We determine to what extent a certain choice of G and H
influences its computational complexity. We observe that the problem is
polynomial-time solvable if H is the class of paths, whereas it is NP-complete
if G is the class of paths. Moreover, we show that the problem is even
NP-complete on many other elementary graph classes, namely linear forests,
unions of complete graphs, cographs, proper interval graphs, split graphs and
trees of pathwidth at most 2. In contrast, we prove that the problem is
fixed-parameter tractable in k if G is the class of trees and H is the class of
trees with at most k leaves, or if G and H are equal to the class of graphs
with vertex cover number at most k.Comment: 13 pages, 5 figure