317 research outputs found
Applying spatial reasoning to topographical data with a grounded geographical ontology
Grounding an ontology upon geographical data has been pro-
posed as a method of handling the vagueness in the domain more effectively. In order to do this, we require methods of reasoning about the spatial relations between the regions within the data. This stage can be computationally expensive, as we require information on the location of
points in relation to each other. This paper illustrates how using knowledge about regions allows us to reduce the computation required in an efficient and easy to understand manner. Further, we show how this system can be implemented in co-ordination with segmented data to reason abou
Measurement and PC-SAFT modeling of solid-liquid equilibrium of deep eutectic solvents of quaternary ammonium chlorides and carboxylic acids
In this study the solid-liquid equilibria (SLE) of 15 binary mixtures composed of one of three different symmetrical quaternary ammonium chlorides and one of five different fatty acids were measured. The experimental data obtained showed extreme negative deviations to ideality causing large melting-temperature depressions (up to 300 K) that are characteristic for deep eutectic systems. The experimental data revealed that cross-interactions between quaternary ammonium salt and fatty acid increase with increasing alkyl chain length of the quaternary ammonium chloride and with increasing chain length of the carboxylic acid. The pronounced decrease of melting temperatures in these deep eutectic systems is mainly caused by strong hydrogen-bonding interactions, and thermodynamic modeling required an approach that takes hydrogen bonding into account. Thus, the measured phase diagrams were modeled with perturbed-chain statistical associating fluid theory based on the classical molecular homonuclear approach. The model showed very good agreement with the experimental data using a semi-predictive modeling approach, in which binary interaction parameters between quaternary ammonium chloride and carboxylic acid correlated with chain length of the components. This supports the experimental findings on the phase behavior and interactions present in these systems and it allows estimating eutectic points of such highly non-ideal mixtures.This work was developed in the scope of the project CICECO e
Aveiro Institute of Materials, POCI-01-0145-FEDER-007679
(Ref. FCT UID/CTM/50011/2013) and LSRE-LCM, POCI-01-0145-
FEDER-006984jUID/EQU/50020/2013, financed by national funds
through the FCT/MEC and when appropriate co-financed by FEDER
under the PT2020 Partnership Agreement. M.A.R.M acknowledges
FCT for her PhD grant (SFRH/BD/87084/2012). FCT is also
acknowledged for funding the project DeepBiorefinery (PTDC/AGRTEC/
1191/2014). P.V.A.P., G.J.M., M.D.H. and E.A.C.B thank the national
funding agencies CNPq (National Council for Scientific and
Technological Development) (305870/2014-9, 309780/2014,
406856/2013-3), FAPESP (Research Support Foundation of the State
of S~ao Paulo) (2014/21252-0, 2016/08566-1), FAEPEX/UNICAMP
(Fund for Research, Teaching, and Extension) (0125/16) and
CAPES (Coordination of Improvement of Higher Level Personnel)
for financial support and scholarships. E.A.C thanks
Erasmusþ program of the European Union for co-funding.info:eu-repo/semantics/publishedVersio
Sr2V3O9 and Ba2V3O9: quasi one-dimensional spin-systems with an anomalous low temperature susceptibility
The magnetic behaviour of the low-dimensional Vanadium-oxides Sr2V3O9 and
Ba2V3O9 was investigated by means of magnetic susceptibility and specific heat
measurements. In both compounds, the results can be very well described by an
S=1/2 Heisenberg antiferromagnetic chain with an intrachain exchange of J = 82
K and J = 94 K in Sr2V3O9 and Ba2V3O9, respectively. In Sr2V3O9,
antiferromagnetic ordering at T_N = 5.3 K indicate a weak interchain exchange
of the order of J_perp ~ 2 K. In contrast, no evidence for magnetic order was
found in Ba2V3O9 down to 0.5 K, pointing to an even smaller interchain
coupling. In both compounds, we observe a pronounced Curie-like increase of the
susceptibility below 30 K, which we tentatively attribute to a staggered field
effect induced by the applied magnetic field. Results of LDA calculations
support the quasi one-dimensional character and indicate that in Sr2V3O9, the
magnetic chain is perpendicular to the structural one with the magnetic
exchange being transferred through VO4 tetrahedra.Comment: Submitted to Phy. Rev.
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Search for new physics in events with opposite-sign leptons, jets, and missing transverse energy in pp collisions at sqrt(s) = 7 TeV
A search is presented for physics beyond the standard model (BSM) in final
states with a pair of opposite-sign isolated leptons accompanied by jets and
missing transverse energy. The search uses LHC data recorded at a
center-of-mass energy sqrt(s) = 7 TeV with the CMS detector, corresponding to
an integrated luminosity of approximately 5 inverse femtobarns. Two
complementary search strategies are employed. The first probes models with a
specific dilepton production mechanism that leads to a characteristic kinematic
edge in the dilepton mass distribution. The second strategy probes models of
dilepton production with heavy, colored objects that decay to final states
including invisible particles, leading to very large hadronic activity and
missing transverse energy. No evidence for an event yield in excess of the
standard model expectations is found. Upper limits on the BSM contributions to
the signal regions are deduced from the results, which are used to exclude a
region of the parameter space of the constrained minimal supersymmetric
extension of the standard model. Additional information related to detector
efficiencies and response is provided to allow testing specific models of BSM
physics not considered in this paper.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV
The Lambda(b) differential production cross section and the cross section
ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum
pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7
TeV using data collected by the CMS experiment at the LHC. The measurements are
based on Lambda(b) decays reconstructed in the exclusive final state J/Psi
Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and
Lambda to proton pion, using a data sample corresponding to an integrated
luminosity of 1.9 inverse femtobarns. The product of the cross section times
the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls
faster than that of b mesons. The measured value of the cross section times the
branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06
+/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for
anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are
statistical and systematic, respectively.Comment: Submitted to Physics Letters
Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV
Isolated photon production is measured in proton-proton and lead-lead
collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the
pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80
GeV with the CMS detector at the LHC. The measured ET spectra are found to be
in good agreement with next-to-leading-order perturbative QCD predictions. The
ratio of PbPb to pp isolated photon ET-differential yields, scaled by the
number of incoherent nucleon-nucleon collisions, is consistent with unity for
all PbPb reaction centralities.Comment: Submitted to Physics Letters
Short duration of neutralizing antibody titers after pre-exposure rabies vaccination with suckling mouse brain vaccine
The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products
Context. The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100 000 stars, including large representative samples of the stellar populations in the Galaxy, and a well-defined sample of 60 (plus 20 archive) open clusters. We provide internally consistent results calibrated on benchmark stars and star clusters, extending across a very wide range of abundances and ages. This provides a legacy data set of intrinsic value, and equally a large wide-ranging dataset that is of value for the homogenisation of other and future stellar surveys and Gaia's astrophysical parameters. Aims. This article provides an overview of the survey methodology, the scientific aims, and the implementation, including a description of the data processing for the GIRAFFE spectra. A companion paper introduces the survey results. Methods. Gaia-ESO aspires to quantify both random and systematic contributions to measurement uncertainties. Thus, all available spectroscopic analysis techniques are utilised, each spectrum being analysed by up to several different analysis pipelines, with considerable effort being made to homogenise and calibrate the resulting parameters. We describe here the sequence of activities up to delivery of processed data products to the ESO Science Archive Facility for open use. Results. The Gaia-ESO Survey obtained 202 000 spectra of 115 000 stars using 340 allocated VLT nights between December 2011 and January 2018 from GIRAFFE and UVES. Conclusions. The full consistently reduced final data set of spectra was released through the ESO Science Archive Facility in late 2020, with the full astrophysical parameters sets following in 2022. A companion article reviews the survey implementation, scientific highlights, the open cluster survey, and data products
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