There has long been a debate as to whether desert varnish deposits are microbially mediated or are deposited by inorganic processes. Several researchers have cultured bacteria from the surface of ...desert varnish suggesting that bacteria are intimately associated with varnish coatings and may play a role in their formation. To test this hypothesis, we have collected scrapings of desert varnish from the Sonoran Desert in Arizona and the Mojave Desert in California and analyzed them for amino acids. Thirteen amino acids were found in desert varnish indicating a biogenic component of these varnishes. Two protein amino acids that were not detected in any of the varnishes are cysteine and tryptophan. Two nonprotein amino acids,β-alanine andγ-amino butyric acid, were found. These are known to be formed by enzymatic decarboxylation, thereby indicating possible organismal activity in varnish. Some D -enantiomers of the amino acids were also found. In addition to small amounts of the D -enantiomer of aspartic acid, which is rapidly formed by racemization and was present in most samples, D -alanine and D -glutamic acid were found. These latter two amino acids are components of the peptidoglycan cell wall material of bacteria. L -lysine was also detected, but not diaminopimelic acid. The combination of L -lysine, D -alanine, and D -glutamic acid is characteristic of the peptidoglycan from Gram-positive bacteria. Although the presence of these biomarkers does not prove that Gram-positive bacteria produce the coatings, finding them is consistent with the hypothesis that they may play a role in desert varnish formation.
Aims. NGC 2992 is an intermediate Seyfert 1 galaxy showing outflows on kilo parsec scales which might be due either to AGN or starburst activity. We therefore aim at investigating its central region ...for a putative starburst in the past and its connection to the AGN and the outflows. Methods. Observations were performed with the adaptive optics near infrared integral field spectrograph SINFONI on the VLT, complemented by longslit observations with ISAAC on the VLT, as well as N- and Q-band data from the Spitzer archive. The spatial and spectral resolutions of the SINFONI data are 50 pc and 83 km s super(-1), respectively. The field of view of × corresponds to 450 pc × 450 pc. Brγ equivalent width and line fluxes from PAHs were compared to stellar population models to constrain the age of the putative recent star formation. A simple geometric model of two mutually inclined disks and an additional cone to describe an outflow was developed to explain the observed complex velocity field in H sub(2) 1– 0S(1). Results. The morphologies of the Brγ and the stellar continuum are different suggesting that at least part of the Brγ emission comes from the AGN. This is confirmed by PAH emission lines at 6.2 μ m and 11.2 μ m and the strength of the silicon absorption feature at 9.7 μ m, which point to dominant AGN activity with a relatively minor starburst contribution. We find a starburst age of 40– 50 Myr from Brγ line diagnostics and the radio continuum; ongoing star formation can be excluded. Both the energetics and the timescales indicate that the outflows are driven by the AGN rather than the starburst. The complex velocity field observed in H sub(2) 1– 0S(1) in the central 450 pc can be explained by the superposition of the galaxy rotation and an outflow.
We present spatially resolved distributions and kinematics of the stars and molecular gas in the central 320 pc of NGC 1097. The stellar continuum confirms the previously reported three-arm spiral ...pattern extending into the central 100 pc. The stellar kinematics and the gas distribution imply this is a shadowing effect due to extinction by gas and dust in the molecular spiral arms. The molecular gas kinematics show a strong residual (i.e., non-circular) velocity, which is manifested as a two-arm kinematic spiral. Linear models indicate that this is the line-of-sight velocity pattern expected for a density wave in gas that generates a three-arm spiral morphology. We estimate the inflow rate along the arms. Using hydrodynamical models of nuclear spirals, we show that when deriving the accretion rate into the central region, outflow in the disk plane between the arms has to be taken into account. For NGC 1097, despite the inflow rate along the arms being {approx} 1.2 M{sub sun} yr{sup -1}, the net gas accretion rate to the central few tens of parsecs is much smaller. The numerical models indicate that the inflow rate could be as little as {approx} 0.06 M{sub sun} yr{sup -1}. This is sufficient to generate recurring starbursts, similar in scale to that observed, every 20-150 Myr. The nuclear spiral represents a mechanism that can feed gas into the central parsecs of the galaxy, with the gas flow sustainable for timescales of a gigayear.
Paleomagnetic data and rock magnetic results suggest that a widespread orogenic remagnetization caused a pervasive chemical remanent magnetization (CRM) that resides in magnetite in the Mississippian ...Madison Group in the Sawtooth Range, Montana, during the Late Cretaceous to Early Tertiary. The CRM is similar to a CRM reported by workers from equivalent units in the southern Canadian Cordillera. The CRM is interpreted to be related to alteration by fluids, and there are two likely fluids: hydrocarbons which migrated into the unit and externally derived radiogenic fluids.
Here we have studied the transverse-momentum (pT) dependence of the inclusive J/$\psi$ production in p-Pb collisions at root $\sqrt{s_{N\ N}}$ = 5.02 TeV, in three center-of-mass rapidity (ycms) ...regions, down to zero pT. Results in the forward and backward rapidity ranges (2.03 < ycms < 3.53 and -4.46 < ycms < -2.96) are obtained by studying the J/$\psi$ decay to μ+μ-, while the mid-rapidity region (-1.37 < ycms < 0.43) is investigated by measuring the e+e- decay channel. The pT dependence of the J/$\psi$ production cross section and nuclear modification factor are presented for each of the rapidity intervals, as well as the J/psi mean pT values. Forward and mid-rapidity results show a suppression of the J/$\psi$ yield, with respect to pp collisions, which decreases with increasing pT. At backward rapidity no significant J/$\psi$ suppression is observed. Theoretical models including a combination of cold nuclear matter effects such as shadowing and partonic energy loss, are in fair agreement with the data, except at forward rapidity and low transverse momentum. Finally, the implications of the p-Pb results for the evaluation of cold nuclear matter effects on J/$\psi$ production in Pb-Pb collisions are also discussed.
We have studied the transverse-momentum (p T) dependence of the inclusive J/ψ production in p-Pb collisions at $\sqrt{^sNN}$ = 5.02 TeV, in three center-of-mass rapidity (y cms) regions, down to zero ...p T. Results in the forward and backward rapidity ranges (2.03 < y cms < 3.53 and –4.46 < y cms < –2.96) are obtained by studying the J/ψ decay to μ + μ –, while the mid-rapidity region (–1.37 < y cms < 0.43) is investigated by measuring the e+e– decay channel. The p T dependence of the J/ψ production cross section and nuclear modification factor are presented for each of the rapidity intervals, as well as the J/ψ mean p T values. Forward and mid-rapidity results show a suppression of the J/ψ yield, with respect to pp collisions, which decreases with increasing p T. At backward rapidity no significant J/ψ suppression is observed. Theoretical models including a combination of cold nuclear matter effects such as shadowing and partonic energy loss, are in fair agreement with the data, except at forward rapidity and low transverse momentum. The implications of the p-Pb results for the evaluation of cold nuclear matter effects on J/ψ production in Pb-Pb collisions are also discussed.
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