5,830 research outputs found
Consistency of cruise data of the CARINA database in the Atlantic sector of the Southern Ocean
Initially a North Atlantic project, the CARINA carbon synthesis was extended to include the Southern Ocean. Carbon and relevant hydrographic and geochemical ancillary data from cruises all across the Arctic Mediterranean Seas, Atlantic and Southern Ocean were released to the public and merged into a new database as part of the CARINA synthesis effort. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean, including 11 from the Atlantic sector. The variables from all Southern Ocean cruises, including dissolved inorganic carbon (TCO2), total alkalinity, oxygen, nitrate, phosphate and silicate, were examined for cruise-to-cruise consistency in one collective effort. Seawater pH and chlorofluorocarbons (CFCs) are also part of the database, but the pH quality control (QC) is described in another Earth System Science Data publication, while the complexity of the Southern Ocean physics and biogeochemistry prevented a proper QC analysis of the CFCs. The area-specific procedures of quality control, including crossover analysis between stations and inversion analysis of all crossover data (i.e. secondary QC), are briefly described here for the Atlantic sector of the Southern Ocean. Data from an existing, quality controlled database (GLODAP) were used as a reference for our computations – however, the reference data were included into the analysis without applying the recommended GLODAP adjustments so the corrections could be independently verified. The outcome of this effort is an internally consistent, high-quality carbon data set for all cruises, including the reference cruises. The suggested corrections by the inversion analysis were allowed to vary within a fixed envelope, thus accounting for natural variability. The percentage of cruises adjusted ranged from 31% (for nitrate) to 54% (for phosphate) depending on the variable
Catch bond drives stator mechanosensitivity in the bacterial flagellar motor
The bacterial flagellar motor (BFM) is the rotary motor that rotates each bacterial flagellum, powering the swimming and swarming of many motile bacteria. The torque is provided by stator units, ion motive force-powered ion channels known to assemble and disassemble dynamically in the BFM. This turnover is mechanosensitive, with the number of engaged units dependent on the viscous load experienced by the motor through the flagellum. However, the molecular mechanism driving BFM mechanosensitivity is unknown. Here, we directly measure the kinetics of arrival and departure of the stator units in individual motors via analysis of high-resolution recordings of motor speed, while dynamically varying the load on the motor via external magnetic torque. The kinetic rates obtained, robust with respect to the details of the applied adsorption model, indicate that the lifetime of an assembled stator unit increases when a higher force is applied to its anchoring point in the cell wall. This provides strong evidence that a catch bond (a bond strengthened instead of weakened by force) drives mechanosensitivity of the flagellar motor complex. These results add the BFM to a short, but growing, list of systems demonstrating catch bonds, suggesting that this "molecular strategy" is a widespread mechanism to sense and respond to mechanical stress. We propose that force-enhanced stator adhesion allows the cell to adapt to a heterogeneous environmental viscosity and may ultimately play a role in surface-sensing during swarming and biofilm formation
Gravitational Chern-Simons Lagrangians and black hole entropy
We analyze the problem of defining the black hole entropy when Chern-Simons
terms are present in the action. Extending previous works, we define a general
procedure, valid in any odd dimensions both for purely gravitational CS terms
and for mixed gauge-gravitational ones. The final formula is very similar to
Wald's original formula valid for covariant actions, with a significant
modification. Notwithstanding an apparent violation of covariance we argue that
the entropy formula is indeed covariant.Comment: 39 page
Screening of Metarhizium spp. strains for anticancer indolizidine alkaloid production and its rapid detection by MS analysis
Six fungi strains ( M. anisopliae 3935, 4516, 4819, PL57, PL43 and M. flavoviride CG291) were studied regarding their ability to produce an anticancer indolizidine alkaloid. The culture process was carried out in Shaken flask at 26 C and 200 rpm using three different culture medium containing oat meal extract supplemented with glucose and DL-lysine or Czapek culture medium. The mycelial extracts produced by Metarhizium spp. cultures were directly submitted to electrospray ionization mass spectrometry ( ESI-MS) analysis and the highest alkaloid concentration ( approximately, 6 mg.L-1) was reached when M. anisopliae 3935 was tested.38478078
EFFECT OF THE PRECURSOR ADDITION ON THE ANTICANCER ALKALOID PRODUCTION USING EXPERIMENTAL DESIGN METHODOLOGY.
EFFECT OF THE PRECURSOR ADDITION ON THE ANTICANCER ALKALOID PRODUCTION USING EXPERIMENTAL DESIGN METHODOLOGY. The effect of precursors on the anticancer alkaloid production by submerged fermentation using M. anisopliae 3935 was studied, according to complete experimental design 2(2) with three central points. The results showed that lysine was the most important variable, however, when both lysine and glucose were added to the fermentation medium, the alkaloid production reached, approximately, 17 mg L(-1) after 120 hours of fermentation. Then. the scale-up of the process was carried out and these results were confirmed. Finally, 35 mg L(-1) of alkaloid at 192 It were attained after increment of added aminoacid lysine.3261394139
Energy-Aware Self-Adaptation for Application Execution on Heterogeneous Parallel Architectures
Hardware in High Performance Computing environments in recent years have increasingly become more heterogeneous in order to improve computational performance. An additional aspect of such systems is the management of power and energy consumption. The increase in heterogeneity requires middleware and programming model abstractions to eliminate additional complexities that it brings, while also offering opportunities such as improved power management. In this paper, we explore application level self-adaptation including aspects such as automated configuration and deployment of applications to different heterogeneous infrastructure and for their redeployment. This therefore not only mitigates complexities associated with heterogeneous devices but aims to take advantage of the heterogeneity. The overall result of this paper is a self-adaptive framework that manages application Quality of Service (QoS) at runtime, which includes the automatic migration of applications between different accelerated infrastructures. Discussion covers when this migration is appropriate and quantifies the likely benefits
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The programming of sequences of saccades
Saccadic eye movements move the high-resolution fovea to point at regions of interest. Saccades can only be generated serially (i.e., one at a time). However, what remains unclear is the extent to which saccades are programmed in parallel (i.e., a series of such moments can be planned together) and how far ahead such planning occurs. In the current experiment, we investigate this issue with a saccade contingent preview paradigm. Participants were asked to execute saccadic eye movements in response to seven small circles presented on a screen. The extent to which participants were given prior information about target locations was varied on a trial-by-trial basis: participants were aware of the location of the next target only, the next three, five, or all seven targets. The addition of new targets to the display was made during the saccade to the next target in the sequence. The overall time taken to complete the sequence was decreased as more targets were available up to all seven targets. This was a result of a reduction in the number of saccades being executed and a reduction in their saccade latencies. Surprisingly, these results suggest that, when faced with a demand to saccade to a large number of target locations, saccade preparation about all target locations is carried out in paralle
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The concurrent programming of saccades
Sequences of saccades have been shown to be prepared concurrently however it remains unclear exactly what aspects of those saccades are programmed in parallel. To examine this participants were asked to make one or two target-driven saccades: a reflexive saccade; a voluntary saccade; a reflexive then a voluntary saccade; or vice versa. During the first response the position of a second target was manipulated. The new location of the second saccade target was found to impact on second saccade latencies and second saccade accuracy showing that some aspects of the second saccade program are prepared in parallel with the first. However, differences were found in the specific pattern of effects for each sequence type. These differences fit well within a general framework for saccade control in which a common priority map for saccade control is computed and the influence of saccade programs on one another depends not so much on the types of saccade being produced but rather on the rate at which their programs develop
Morphodynamics, boundary conditions and pattern evolution within a vegetated linear dunefield
publisher: Elsevier articletitle: Morphodynamics, boundary conditions and pattern evolution within a vegetated linear dunefield journaltitle: Geomorphology articlelink: http://dx.doi.org/10.1016/j.geomorph.2017.03.024 content_type: article copyright: © 2017 Elsevier B.V. All rights reserved
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