2,490 research outputs found
Caracterização composicional e estrutural dos ácidos húmicos de solos de Tabuleiros sob diferentes coberturas vegetais.
Avaliou-se o efeito de diferentes coberturas vegetais sobre composição química espectroscópica de ácidos húmicos (AH) em áreas de Latossolo e Argissolo Amarelo, em Campos dos Goytacazes (RJ). Foram estudadas três áreas: pastagem, cana-de-açúcar e floresta secundária. Foi determinado o teor de cinza, a composição elementar (CHNO) e espectros da região do UV-vis e do infravermelho (IV). Os AH apresentaram em média 46,5% de carbono (C) e 3,9% de nitrogênio (N), 5,6% hidrogênio (H) e 45,0% de oxigênio (O). A razão H:C apresentou valores entre 1,32 e 1,74, menores no pasto e maiores na floresta, e para a razão O:C, valores entre 0,66 e 0,88, menores no pasto e maiores na área de cana, porém semelhantes na cana e floresta. Pelos espectros do UV-vis observou-se relação E4/E6 variando de 4,5 a 7,0, menores no pasto e cana e maiores na floresta. Pelos espectros do IV verificou-se que os AH da floresta na área de Argissolo apresentaram uma banda de absorção em torno de 1540 cm-1, indicando a presença de deformação N-H ou estiramento C=N (amida secundária). Os AH da floresta e em especial sob Argissolo foram mais alifáticos, indicando a presença de compostos menos evoluídos em relação às outras coberturas
A computational modeling for real ecosystems based on P systems
In this paper, a P systems based general framework for modeling ecosystems
dynamics is presented. Particularly, ecosystems are specified by means of multienvironment
P systems composed of a finite number of environments, each of them having an
extended P system with active membranes. The semantics is of a probabilistic type and it is
implemented by assigning each rule of the system a probabilistic constant which depends
on the environment and the run time. As a case study, two real ecosystems are described:
scavenger birds in the Catalan Pyrenees and the zebra mussel (Dreissena Polymorpha) in
Ribarroja reservoir (Spain).Ministerio de Ciencia e Innovación TIN2009–13192Junta de Andalucía P08–TIC-0420
Spectro-photometric close pairs in GOODS-S: major and minor companions of intermediate-mass galaxies
(Abriged) Our goal here is to provide merger frequencies that encompass both
major and minor mergers, derived from close pair statistics. We use B-band
luminosity- and mass-limited samples from an Spitzer/IRAC-selected catalogue of
GOODS-S. We present a new methodology for computing the number of close
companions, Nc, when spectroscopic redshift information is partial. We select
as close companions those galaxies separated by 6h^-1 kpc < rp < 21h^-1 kpc in
the sky plane and with a difference Delta_v <= 500 km s^-1 in redshift space.
We provide Nc for four different B-band-selected samples. Nc increases with
luminosity, and its evolution with redshift is faster in more luminous samples.
We provide Nc of M_star >= 10^10 M_Sun galaxies, finding that the number
including minor companions (mass ratio >= 1/10) is roughly two times the number
of major companions alone (mass ratio >= 1/3) in the range 0.2 <= z < 1.1. We
compare the major merger rate derived by close pairs with the one computed by
morphological criteria, finding that both approaches provide similar merger
rates for field galaxies when the progenitor bias is taken into account.
Finally, we estimate that the total (major+minor) merger rate is ~1.7 times the
major merger rate. Only 30% to 50% of the M_star >= 10^10 M_Sun early-type
(E/S0/Sa) galaxies that appear z=1 and z=0 may have undergone a major or a
minor merger. Half of the red sequence growth since z=1 is therefore unrelated
to mergers.Comment: Accepted in A&A. 14 pages, 6 figures, 8 tables. We have tested the
method with a local, volume-limited spectroscopic sample
Extended-Spectrum-Beta-Lactamases, AmpC Beta-Lactamases and Plasmid Mediated Quinolone Resistance in Klebsiella spp. from Companion Animals in Italy
We report the genetic characterization of 15 Klebsiella pneumoniae (KP) and 4 isolates of K. oxytoca (KO) from clinical cases in dogs and cats and showing extended-spectrum cephalosporin (ESC) resistance. Extended spectrum beta-lactamase (ESBL) and AmpC genes, plasmid-mediated quinolone resistance (PMQR) and co-resistances were investigated. Among KP isolates, ST101 clone was predominant (8/15, 53%), followed by ST15 (4/15, 27%). ST11 and ST340, belonging to Clonal Complex (CC)11, were detected in 2012 (3/15, 20%). MLST on KP isolates corresponded well with PFGE results, with 11 different PFGE patterns observed, including two clusters of two (ST340) and four (ST101) indistinguishable isolates, respectively. All isolates harbored at least one ESBL or AmpC gene, all carried on transferable plasmids (IncR, IncFII, IncI1, IncN), and 16/19 were positive for PMQR genes (qnr family or aac(6')-Ib-cr). The most frequent ESBL was CTX-M-15 (11/19, 58%), detected in all KP ST101, in one KP ST15 and in both KP ST340. blaCTX-M-15 was carried on IncR plasmids in all but one KP isolate. All KP ST15 isolates harbored different ESC resistance genes and different plasmids, and presented the non-transferable blaSHV-28 gene, in association with blaCTX-M-15, blaCTX-M-1 (on IncR, or on IncN), blaSHV-2a (on IncR) or blaCMY-2 genes (on IncI1). KO isolates were positive for blaCTX-M-9 gene (on IncHI2), or for the blaSHV-12 and blaDHA-1 genes (on IncL/M). They were all positive for qnr genes, and one also for the aac(6')-Ib-cr gene. All Klebsiella isolates showed multiresistance towards aminoglycosides, sulfonamides, tetracyclines, trimethoprim and amphenicols, mediated by strA/B, aadA2, aadB, ant (2")-Ia, aac(6')-Ib, sul, tet, dfr and cat genes in various combinations. The emergence in pets of multidrug-resistant Klebsiella with ESBL, AmpC and PMQR determinants, poses further and serious challenges in companion animal therapy and raise concerns for possible bi-directional transmission between pets and humans, especially at household level
On the buildup of massive early-type galaxies at z<~1. I- Reconciling their hierarchical assembly with mass-downsizing
Several studies have tried to ascertain whether or not the increase in
abundance of the early-type galaxies (E-S0a's) with time is mainly due to major
mergers, reaching opposite conclusions. We have tested it directly through
semi-analytical modelling, by studying how the massive early-type galaxies with
log(M_*/Msun)>11 at z~0 (mETGs) would have evolved backwards-in-time, under the
hypothesis that each major merger gives place to an early-type galaxy. The
study was carried out just considering the major mergers strictly reported by
observations at each redshift, and assuming that gas-rich major mergers
experience transitory phases of dust-reddened, star-forming galaxies (DSFs).
The model is able to reproduce the observed evolution of the galaxy LFs at
z<~1, simultaneously for different rest-frame bands (B, I, and K) and for
different selection criteria on color and morphology. It also provides a
framework in which apparently-contradictory results on the recent evolution of
the luminosity function (LF) of massive, red galaxies can be reconciled, just
considering that observational samples of red galaxies can be significantly
contaminated by DSFs. The model proves that it is feasible to build up ~50-60%
of the present-day mETG population at z<~1 and to reproduce the observational
excess by a factor of ~4-5 of late-type galaxies at 0.8<z<1 through the
coordinated action of wet, mixed, and dry major mergers, fulfilling global
trends that are in general agreement with mass-downsizing. The bulk of this
assembly takes place during ~1 Gyr elapsed at 0.8<z<1. The model suggests that
major mergers have been the main driver for the observational migration of mass
from the massive-end of the blue galaxy cloud to that of the red sequence in
the last ~8 Gyr.(Abridged)Comment: Accepted for publication in Astronomy & Astrophysics; 21 pages, 8
figures. Minor corrections included, shortened title. Results and conclusions
unchange
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
Expression of paclitaxel-inactivating CYP3A activity in human colorectal cancer: implications for drug therapy
Cytochrome P450 3A is a drug-metabolising enzyme activity due to CYP3A4 and CYP3A5 gene products, that is involved in the inactivation of anticancer drugs. This study analyses the potential of cytochrome P450 3A enzyme in human colorectal cancer to impact anticancer therapy with drugs that are cytochrome P450 3A substrates. Enzyme activity, variability and properties, and the ability to inactivate paclitaxel (taxol) were analysed in human colorectal cancer and healthy colorectal epithelium. Cytochrome P450 3A enzyme activity is present in healthy and tumoral samples, with a nearly 10-fold interindividual variability. Nifedipine oxidation activity±s.d. for colorectal cancer microsomes was 67.8±36.6 pmol min−1 mg−1. The Km of the tumoral enzyme (42±8 μM) is similar to that in healthy colorectal epithelium (36±8 μM) and the human liver enzyme. Colorectal cancer microsomes metabolised the anticancer drug paclitaxel with a mean activity was 3.1±1.2 pmol min−1 mg−1. The main metabolic pathway is carried out by cytochrome P450 3A, and it is inhibited by the cytochrome P450 3A-specific inhibitor ketoconazole with a KI value of 31 nM. This study demonstrates the occurrence of cytochrome P450 3A-dependent metabolism in colorectal cancer tissue. The metabolic activity confers to cancer cells the ability to inactivate cytochrome P450 3A substrates and may modulate tumour sensitivity to anticancer drugs
Measurement of the mass and lifetime of the baryon
A proton-proton collision data sample, corresponding to an integrated
luminosity of 3 fb collected by LHCb at and 8 TeV, is used
to reconstruct , decays. Using the , decay mode for calibration, the lifetime ratio and absolute
lifetime of the baryon are measured to be \begin{align*}
\frac{\tau_{\Omega_b^-}}{\tau_{\Xi_b^-}} &= 1.11\pm0.16\pm0.03, \\
\tau_{\Omega_b^-} &= 1.78\pm0.26\pm0.05\pm0.06~{\rm ps}, \end{align*} where the
uncertainties are statistical, systematic and from the calibration mode (for
only). A measurement is also made of the mass difference,
, and the corresponding mass, which
yields \begin{align*} m_{\Omega_b^-}-m_{\Xi_b^-} &= 247.4\pm3.2\pm0.5~{\rm
MeV}/c^2, \\ m_{\Omega_b^-} &= 6045.1\pm3.2\pm 0.5\pm0.6~{\rm MeV}/c^2.
\end{align*} These results are consistent with previous measurements.Comment: 11 pages, 5 figures, 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-2016-008.htm
Differential branching fraction and angular analysis of decays
The differential branching fraction of the rare decay is measured as a function of , the
square of the dimuon invariant mass. The analysis is performed using
proton-proton collision data, corresponding to an integrated luminosity of 3.0
\mbox{ fb}^{-1}, collected by the LHCb experiment. Evidence of signal is
observed in the region below the square of the mass. Integrating
over 15 < q^{2} < 20 \mbox{ GeV}^2/c^4 the branching fraction is measured as
d\mathcal{B}(\Lambda^{0}_{b} \rightarrow \Lambda \mu^+\mu^-)/dq^2 = (1.18 ^{+
0.09} _{-0.08} \pm 0.03 \pm 0.27) \times 10^{-7} ( \mbox{GeV}^{2}/c^{4})^{-1},
where the uncertainties are statistical, systematic and due to the
normalisation mode, , respectively.
In the intervals where the signal is observed, angular distributions are
studied and the forward-backward asymmetries in the dimuon ()
and hadron () systems are measured for the first time. In the
range 15 < q^2 < 20 \mbox{ GeV}^2/c^4 they are found to be A^{l}_{\rm FB} =
-0.05 \pm 0.09 \mbox{ (stat)} \pm 0.03 \mbox{ (syst)} and A^{h}_{\rm FB} =
-0.29 \pm 0.07 \mbox{ (stat)} \pm 0.03 \mbox{ (syst)}.Comment: 27 pages, 10 figures, Erratum adde
Measurement of the lifetime
Using a data set corresponding to an integrated luminosity of ,
collected by the LHCb experiment in collisions at centre-of-mass energies
of 7 and 8 TeV, the effective lifetime in the
decay mode, , is measured to be ps. Assuming
conservation, corresponds to the lifetime of the light
mass eigenstate. This is the first measurement of the effective
lifetime in this decay mode.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-2016-017.htm
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