66 research outputs found
Metagenomics of the Deep Mediterranean, a Warm Bathypelagic Habitat
BACKGROUND: Metagenomics is emerging as a powerful method to study the function and physiology of the unexplored microbial biosphere, and is causing us to re-evaluate basic precepts of microbial ecology and evolution. Most marine metagenomic analyses have been nearly exclusively devoted to photic waters. METHODOLOGY/PRINCIPAL FINDINGS: We constructed a metagenomic fosmid library from 3,000 m-deep Mediterranean plankton, which is much warmer (approximately 14 degrees C) than waters of similar depth in open oceans (approximately 2 degrees C). We analyzed the library both by phylogenetic screening based on 16S rRNA gene amplification from clone pools and by sequencing both insert extremities of ca. 5,000 fosmids. Genome recruitment strategies showed that the majority of high scoring pairs corresponded to genomes from Rhizobiales within the Alphaproteobacteria, Cenarchaeum symbiosum, Planctomycetes, Acidobacteria, Chloroflexi and Gammaproteobacteria. We have found a community structure similar to that found in the aphotic zone of the Pacific. However, the similarities were significantly higher to the mesopelagic (500-700 m deep) in the Pacific than to the single 4000 m deep sample studied at this location. Metabolic genes were mostly related to catabolism, transport and degradation of complex organic molecules, in agreement with a prevalent heterotrophic lifestyle for deep-sea microbes. However, we observed a high percentage of genes encoding dehydrogenases and, among them, cox genes, suggesting that aerobic carbon monoxide oxidation may be important in the deep ocean as an additional energy source. CONCLUSIONS/SIGNIFICANCE: The comparison of metagenomic libraries from the deep Mediterranean and the Pacific ALOHA water column showed that bathypelagic Mediterranean communities resemble more mesopelagic communities in the Pacific, and suggests that, in the absence of light, temperature is a major stratifying factor in the oceanic water column, overriding pressure at least over 4000 m deep. Several chemolithotrophic metabolic pathways could supplement organic matter degradation in this most depleted habitat
Spin-independent interferences and spin-dependent interactions with scalar dark matter
Observation of Two New Excited Îb0 States Decaying to Îb0 K-Ï+
Two narrow resonant states are observed in the Îb0K-Ï+ mass spectrum using a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 6 fb-1. The minimal quark content of the Îb0K-Ï+ system indicates that these are excited Îb0 baryons. The masses of the Îb(6327)0 and Îb(6333)0 states are m[Îb(6327)0]=6327.28-0.21+0.23±0.12±0.24 and m[Îb(6333)0]=6332.69-0.18+0.17±0.03±0.22 MeV, respectively, with a mass splitting of Îm=5.41-0.27+0.26±0.12 MeV, where the uncertainties are statistical, systematic, and due to the Îb0 mass measurement. The measured natural widths of these states are consistent with zero, with upper limits of Î[Îb(6327)0]<2.20(2.56) and Î[Îb(6333)0]<1.60(1.92) MeV at a 90% (95%) credibility level. The significance of the two-peak hypothesis is larger than nine (five) Gaussian standard deviations compared to the no-peak (one-peak) hypothesis. The masses, widths, and resonant structure of the new states are in good agreement with the expectations for a doublet of 1D Îb0 resonances
Measurement of the CKM angle using with decays
A model-dependent amplitude analysis of the decay is performed using proton-proton collision data
corresponding to an integrated luminosity of 3.0fb, recorded at
and by the LHCb experiment. The CP violation observables
and , sensitive to the CKM angle , are measured to
be \begin{eqnarray*} x_- &=& -0.15 \pm 0.14 \pm 0.03 \pm 0.01, y_- &=& 0.25 \pm
0.15 \pm 0.06 \pm 0.01, x_+ &=& 0.05 \pm 0.24 \pm 0.04 \pm 0.01, y_+ &=&
-0.65^{+0.24}_{-0.23} \pm 0.08 \pm 0.01, \end{eqnarray*} where the first
uncertainties are statistical, the second systematic and the third arise from
the uncertainty on the amplitude model. These
are the most precise measurements of these observables. They correspond to
and , where is
the magnitude of the ratio of the suppressed and favoured decay amplitudes, in a mass region of around the
mass and for an absolute value of the cosine of the decay
angle larger than .Comment: 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-2016-007.htm
First experimental study of photon polarization in radiative B-s(0) decays
The polarization of photons produced in radiative B0s decays is studied for the first time. The data are recorded by the LHCb experiment in pp collisions corresponding to an integrated luminosity of 3ââfbâ1 at center-of-mass energies of 7 and 8 TeV. A time-dependent analysis of the B0sâÏÎł decay rate is conducted to determine the parameter AÎ, which is related to the ratio of right- over left-handed photon polarization amplitudes in bâsÎł transitions. A value of AÎ=â0.98+0.46â0.52+0.23â0.20 is measured. This result is consistent with the standard model prediction within 2 standard deviations
Search for dark photons produced in 13 TeV collisions
Searches are performed for both promptlike and long-lived dark photons,
A
0
, produced in proton-proton
collisions at a center-of-mass energy of 13 TeV, using
A
0
â
Ό
ĂŸ
Ό
â
decays and a data sample corresponding
to an integrated luminosity of
1
.
6
fb
â
1
collected with the LHCb detector. The promptlike
A
0
search covers
the mass range from near the dimuon threshold up to 70 GeV, while the long-lived
A
0
search is restricted to
the low-mass region
214
<m
Ă°
A
0
Ă
<
350
MeV. No evidence for a signal is found, and 90% confidence
level exclusion limits are placed on the
Îł
â
A
0
kinetic-mixing strength. The constraints placed on promptlike
dark photons are the most stringent to date for the mass range
10
.
6
<m
Ă°
A
0
Ă
<
70
GeV, and are
comparable to the best existing limits for
m
Ă°
A
0
Ă
<
0
.
5
GeV. The search for long-lived dark photons is the
first to achieve sensitivity using a displaced-vertex signature
Direct CP violation in charmless three-body decays of B± mesons
Measurements of
C
P
asymmetries in charmless three-body decays of
B
±
mesons are reported using proton-proton collision data collected by the LHCb detector, corresponding to an integrated luminosity of
5.9
â
â
fb
â
1
. The previously observed
C
P
asymmetry in
B
±
â
Ï
±
K
+
K
â
decays is confirmed, and
C
P
asymmetries are observed with a significance of more than five standard deviations in the
B
±
â
Ï
±
Ï
+
Ï
â
and
B
±
â
K
±
K
+
K
â
decays, while the
C
P
asymmetry of
B
±
â
K
±
Ï
+
Ï
â
decays is confirmed to be compatible with zero. The distributions of these asymmetries are also studied as a function of the three-body phase space and suggest contributions from rescattering and resonance interference processes. An indication of the presence of the decays
B
±
â
Ï
±
Ï
c
0
(
1
P
)
in both
B
±
â
Ï
±
Ï
+
Ï
â
and
B
±
â
Ï
±
K
+
K
â
decays is observed, as is
C
P
violation involving these amplitudes
Measurement of antiproton production from antihyperon decays in p He collisions at âsNN = 110 GeV
The interpretation of cosmic antiproton flux measurements from space-borne experiments is currently limited by the knowledge of the antiproton production cross-section in collisions between primary cosmic rays and the interstellar medium. Using collisions of protons with an energy of 6.5TeV incident on helium nuclei at rest in the proximity of the interaction region of the LHCb experiment, the ratio of antiprotons originating from antihyperon decays to prompt production is measured for antiproton momenta between 12 and 110GeV. The dominant antihyperon contribution, namely ÎÂŻâpÂŻÏ+ decays from promptly produced ÎÂŻ particles, is also exclusively measured. The results complement the measurement of prompt antiproton production obtained from the same data sample. At the energy scale of this measurement, the antihyperon contributions to antiproton production are observed to be significantly larger than predictions of commonly used hadronic production models
Measurement of J/Ï -pair production in pp collisions at âs = 13 TeV and study of gluon transverse-momentum dependent PDFs
The production cross-section of J/Ï pairs in proton-proton collisions at a centre-of-mass energy of âs = 13 TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fbâ1 collected by the LHCb experiment. The measurement is performed with both J/Ï mesons in the transverse momentum range 0 < pT< 14 GeV/c and rapidity range 2.0 < y < 4.5. The cross-section of this process is measured to be 16.36 ± 0.28 (stat) ± 0.88 (syst) nb. The contributions from single-parton scattering and double-parton scattering are separated based on the dependence of the cross-section on the absolute rapidity difference ây between the two J/Ï mesons. The effective cross-section of double-parton scattering is measured to be Ïeff = 13.1 ± 1.8 (stat) ± 2.3 (syst) mb. The distribution of the azimuthal angle ÏCS of one of the J/Ï mesons in the Collins-Soper frame and the pT-spectrum of the J/Ï pairs are also measured for the study of the gluon transverse-momentum dependent distributions inside protons. The extracted values of âšcos 2ÏCSâ© and âšcos 4ÏCSâ© are consistent with zero, but the presence of azimuthal asymmetry at a few percent level is allowed
Pd(II)-Ni(II) Pyrazolate Framework as Active and Recyclable Catalyst for the Hydroamination of Terminal Alkynes
© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Abstract: Well-dispersed [Pd(NH3)4]2+ sites have been introduced in the defective nickel pyrazolate porous framework, known as K@NiBDP. The resulting porous crystalline material shows a superior catalytic behavior for CâN bond formations than [Pd(NH3)4]2+ containing zeolite HY. The palladium exchanged catalyst, Pd@NiBDP, is able to promote both intra- and intermolecular hydroamination of terminal alkynes with excellent activity, reusability and selectivity towards the corresponding indole or imine versus the hydration of the alkyne. The same Pd species introduced in the microporous acid HY zeolite favors the hydration of the terminal alkyne towards the corresponding ketone, instead of the addition of the amine to the triple bond. Graphical Abstract: [Figure not available: see fulltext.].status: publishe
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