104 research outputs found
Experimental analysis of R-134a flow condensation in a smooth tube
Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.Condensation processes inside tubes are widely used in air
conditioning and refrigeration industry, since they promote an
improvement of the heat transfer, reducing the equipment size.
The distribution of the liquid and vapour phases inside the
tubes is crucial in the heat transfer process. Several studies have
been carried out for flow regime maps and flow regime
prediction techniques, in order to predict which flow pattern is
expected according to parameters such as the geometry of the
tubes, the flow rate and refrigerant properties. In this work, an
experimental research was conducted to obtain different
condensation flow patterns inside an 8 mm inner diameter
smooth copper tube. Experiments were carried out for mass
fluxes of 100, 200, 300, 400 and 600 kg/m2s, a saturation
temperature of 40 ÂșC and varying the vapour quality from 0.20
to 0.80 at 0.15 intervals. Experimental photographs and videos
are presented, discussed and compared against the results
provided by some flow pattern maps and prediction techniques
found in the literature.dc201
Body Size Evolution in Extant Oryzomyini Rodents: Cope's Rule or Miniaturization?
At the macroevolutionary level, one of the first and most important hypotheses that proposes an evolutionary tendency in the evolution of body sizes is âCope's rule". This rule has considerable empirical support in the fossil record and predicts that the size of species within a lineage increases over evolutionary time. Nevertheless, there is also a large amount of evidence indicating the opposite pattern of miniaturization over evolutionary time. A recent analysis using a single phylogenetic tree approach and a Bayesian based model of evolution found no evidence for Cope's rule in extant mammal species. Here we utilize a likelihood-based phylogenetic method, to test the evolutionary trend in body size, which considers phylogenetic uncertainty, to discern between Cope's rule and miniaturization, using extant Oryzomyini rodents as a study model. We evaluated body size trends using two principal predictions: (a) phylogenetically related species are more similar in their body size, than expected by chance; (b) body size increased (Cope's rule)/decreased (miniaturization) over time. Consequently the distribution of forces and/or constraints that affect the tendency are homogenous and generate this directional process from a small/large sized ancestor. Results showed that body size in the Oryzomyini tribe evolved according to phylogenetic relationships, with a positive trend, from a small sized ancestor. Our results support that the high diversity and specialization currently observed in the Oryzomyini tribe is a consequence of the evolutionary trend of increased body size, following and supporting Cope's rule
Regulatory sites for splicing in human basal ganglia are enriched for disease-relevant information
Genome-wide association studies have generated an increasing number of common genetic variants associated with neurological and psychiatric disease risk. An improved understanding of the genetic control of gene expression in human brain is vital considering this is the likely modus operandum for many causal variants. However, human brain sampling complexities limit the explanatory power of brain-related expression quantitative trait loci (eQTL) and allele-specific expression (ASE) signals. We address this, using paired genomic and transcriptomic data from putamen and substantia nigra from 117 human brains, interrogating regulation at different RNA processing stages and uncovering novel transcripts. We identify disease-relevant regulatory loci, find that splicing eQTLs are enriched for regulatory information of neuron-specific genes, that ASEs provide cell-specific regulatory information with evidence for cellular specificity, and that incomplete annotation of the brain transcriptome limits interpretation of risk loci for neuropsychiatric disease. This resource of regulatory data is accessible through our web server, http://braineacv2.inf.um.es/
First Measurement of the Charge Asymmetry in Beauty-Quark Pair Production
The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in b (b) over bar pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0 fb(-1) collected at 7 TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the b (b) over bar system. The results obtained are A(C)(b (b) over bar) (40 10(5) GeV/c(2)) = 1.6 +/- 1.7 +/- 0.6%,where A(C)(b (b) over bar) is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark, where in each case the first uncertainty is statistical and the second systematic. The beauty jets are required to satisfy 2 20 GeV, and have an opening angle in the transverse plane Delta phi > 2.6 rad. These measurements are consistent with the predictions of the standard model
Observation of the decay Î <sub>b</sub> <sup>0</sup> âââÏ(2S)pÏ<sup>â</sup>
International audienceThe Cabibbo-suppressed decay Î âââÏ(2S)pÏ is observed for the first time using a data sample collected by the LHCb experiment in proton-proton collisions corresponding to 1.0, 2.0 and 1.9 fb of integrated luminosity at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The Ï(2S) mesons are reconstructed in the ΌΌ final state. The branching fraction with respect to that of the Î âââÏ(2S)pK decay mode is measured to b
Observation of B+c â D0K+ decays
Using proton-proton collision data corresponding to an integrated luminosity of 3.0 fbâ1, recorded by
the LHCb detector at center-of-mass energies of 7 and 8 TeV, the B+
c â D0K+ decay is observed with a
statistical significance of 5.1 standard deviations. By normalizing to B+ â DÂŻ 0Ï+ decays, a measurement of
the branching fraction multiplied by the production rates for B+
c relative to B+ mesons in the LHCb
acceptance is obtained, R
D
0
K
=
(
f
c
/
f
u
)
Ă
B
(
B
+
c
â
D
0
K
+
)
=
(
9.
3
+
2.8
â
2.5
±
0.6
)
Ă
10
â
7, where the first
uncertainty is statistical and the second is systematic. This decay is expected to proceed predominantly
through weak annihilation and penguin amplitudes, and is the first B+
c decay of this nature to be observed
Measurement of the B_{s}^{0}âÎŒ^{+}ÎŒ^{-} Branching Fraction and Effective Lifetime and Search for B^{0}âÎŒ^{+}ÎŒ^{-} Decays.
A search for the rare decays B_{s}^{0}âÎŒ^{+}ÎŒ^{-} and B^{0}âÎŒ^{+}ÎŒ^{-} is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4ââfb^{-1}. An excess of B_{s}^{0}âÎŒ^{+}ÎŒ^{-} decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B_{s}^{0}âÎŒ^{+}ÎŒ^{-})=(3.0±0.6_{-0.2}^{+0.3})Ă10^{-9}, where the first uncertainty is statistical and the second systematic. The first measurement of the B_{s}^{0}âÎŒ^{+}ÎŒ^{-} effective lifetime, Ï(B_{s}^{0}âÎŒ^{+}ÎŒ^{-})=2.04±0.44±0.05ââps, is reported. No significant excess of B^{0}âÎŒ^{+}ÎŒ^{-} decays is found, and a 95% confidence level upper limit, B(B^{0}âÎŒ^{+}ÎŒ^{-})<3.4Ă10^{-10}, is determined. All results are in agreement with the standard model expectations
Measurement of the B0sâÎŒ+ÎŒâ Branching Fraction and Effective Lifetime and Search for B0âÎŒ+ÎŒâ Decays
See paper for full list of authors - All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-001.html - Submitted to Phys. Rev. Lett.International audienceA search for the rare decays B0sâÎŒ+ÎŒâ and B0âÎŒ+ÎŒâ is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fbâ1. An excess of B0sâÎŒ+ÎŒâ decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B0sâÎŒ+ÎŒâ)=(3.0±0.6+0.3â0.2)Ă10â9, where the first uncertainty is statistical and the second systematic. The first measurement of the B0sâÎŒ+ÎŒâ effective lifetime, Ï(B0sâÎŒ+ÎŒâ)=2.04±0.44±0.05 ps, is reported. No significant excess of B0âÎŒ+ÎŒâ decays is found and a 95 % confidence level upper limit, B(B0âÎŒ+ÎŒâ)<3.4Ă10â10, is determined. All results are in agreement with the Standard Model expectations
Search for long-lived particles decaying to jet pairs
A search is presented for long-lived particles with a mass between 25 and 50
GeV and a lifetime between 1 and 200 ps in a sample of proton-proton
collisions at a centre-of-mass energy of TeV, corresponding to an
integrated luminosity of 0.62 fb, collected by the LHCb detector. The
particles are assumed to be pair-produced by the decay of a Standard Model-like
Higgs boson. The experimental signature of the long-lived particle is a
displaced vertex with two associated jets. No excess above the background is
observed and limits are set on the production cross-section as a function of
the long-lived particle mass and lifetime
Search for long-lived heavy charged particles using a ring imaging Cherenkov technique at LHCb
A search is performed for heavy long-lived charged particles using 3.0
fb of pp collisions collected at = 7 and 8 TeV with the LHCb
detector. The search is mainly based on the response of the ring imaging
Cherenkovdetectors to distinguish the heavy, slow-moving particles from muons.
No evidence is found for the production of such long-lived states. The results
are expressed as limits on the Drell-Yan production of pairs of long-lived
particles, with both particles in the LHCb pseudorapidity acceptance, . The mass-dependent cross-section upper limits are in the range 2-4
fb (at 95\% CL) for masses between 124 and 309 GeV/c
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