5,239 research outputs found
Techniques for colonial growth and protoplast production in Humicola grisea var. thermoidea
Humicola grisea is a thermophilic, cellulolytic fungus, with significant biotechnological potential for protein secretion. For convenient growth on solid medium, 70% reduction in colony diameter was achieved by the addition of 20 mM sodium citrate to modified Aspergillus complete medium (Pontecorvo et al. 1953, Adv. Genet. 5:141-238)
Gravitational wave recoil in Robinson-Trautman spacetimes
We consider the gravitational recoil due to non-reflection-symmetric
gravitational wave emission in the context of axisymmetric Robinson-Trautman
spacetimes. We show that regular initial data evolve generically into a final
configuration corresponding to a Schwarzschild black-hole moving with constant
speed. For the case of (reflection-)symmetric initial configurations, the mass
of the remnant black-hole and the total energy radiated away are completely
determined by the initial data, allowing us to obtain analytical expressions
for some recent numerical results that have been appeared in the literature.
Moreover, by using the Galerkin spectral method to analyze the non-linear
regime of the Robinson-Trautman equations, we show that the recoil velocity can
be estimated with good accuracy from some asymmetry measures (namely the first
odd moments) of the initial data. The extension for the non-axisymmetric case
and the implications of our results for realistic situations involving head-on
collision of two black holes are also discussed.Comment: 9 pages, 6 figures, final version to appear in PR
Criação de Chrysoperla externa para o controle biológico de pragas do algodoeiro.
bitstream/CNPA-2009-09/14457/1/CIRTEC36.pd
Project-based learning in consecutive modules on geotechnics: foundations
Three conditions of effective learning have been reported: active learning by doing, cooperation and teamwork in learning and learning through problem solving, essential to promote creativity and innovative capacity. Project-based learning can help to promote such skills in engineering programs as it allows recreating professional reality and relating fundamental theories and skills of an engineer. High-level thinking and sound judgment is developed through accumulated authentic professional experience by engineers. For engineering students a similar process can be triggered by a teaching environment which enables simulating and stimulating such skills. To prepare better professional and enhance students' employability Civil Engineering students of University of Aveiro, Portugal, have undertaken several modules on Geotechnics where a project based learning model has been used. These group projects included open-ended realistic scenarios tackled using different tools (spread-sheets and software). This paper refers to a module on Foundations. A collaborative project-based learning model was implemented. Students' perceptions on the added value of the project were collected using a questionnaire and are discussed. Most students had attended two modules on Soil Mechanics where a similar learning model was used, but initially they had negative reactions to it. Students report a severe workload; however their estimates match the expected working hours. The model has been evolving in order to optimise the learning and address the students’ feedback
Black-hole horizons as probes of black-hole dynamics I: post-merger recoil in head-on collisions
The understanding of strong-field dynamics near black-hole horizons is a
long-standing and challenging prob- lem in general relativity. Recent advances
in numerical relativity and in the geometric characterization of black- hole
horizons open new avenues into the problem. In this first paper in a series of
two, we focus on the analysis of the recoil occurring in the merger of binary
black holes, extending the analysis initiated in [1] with Robinson- Trautman
spacetimes. More specifically, we probe spacetime dynamics through the
correlation of quantities defined at the black-hole horizon and at null
infinity. The geometry of these hypersurfaces responds to bulk gravitational
fields acting as test screens in a scattering perspective of spacetime
dynamics. Within a 3 + 1 approach we build an effective-curvature vector from
the intrinsic geometry of dynamical-horizon sections and correlate its
evolution with the flux of Bondi linear momentum at large distances. We employ
this setup to study numerically the head-on collision of nonspinning black
holes and demonstrate its validity to track the qualita- tive aspects of recoil
dynamics at infinity. We also make contact with the suggestion that the
antikick can be described in terms of a "slowness parameter" and how this can
be computed from the local properties of the horizon. In a companion paper [2]
we will further elaborate on the geometric aspects of this approach and on its
relation with other approaches to characterize dynamical properties of
black-hole horizons.Comment: final version published on PR
Soil phosphorus properties and management for perennial crops in the central Amazon.
Predominant soils in the Brazilian Amazon. Phosphorus constraints to continuous soil use in the Brazilian Amazon. Phosphorus fertilization to perennial crops in the central Amazon. Phosphorus budgets in perennial crop plantations
Specificity and kinetics of the milk-clotting enzyme from cardoon (Cynara cardunculus L.) toward bovine .kappa.-casein
The action of Cynara cardunculus L. protease on whole bovine K-casein, over a 3-h period at pH 6.4,
was investigated. RpHPLC of the 3% trichloroacetic acid (TCA)-solublefraction of the K-casein digestion
mixture showed three peptide peaks, which were identified by amino acid analysis and N-terminal
analysis as the 106-169 fragment [caseinomacropeptide (CMP)]. Upon selective precipitation with
12% TCA, one glycosylated and two nonglycosylated forms of CMP were distinguished. Analysis of
the whole digestion mixture showed no additional peptides. The kinetics of hydrolysis of the PhelO5-
Met106 bond was studied by spectrofluorometry, using fluorescein isothiocyanate-labeled K-casein (FTC-
K-casein). The values obtained for kat, k, and k were 1.04 s-l, 0.16 pM, and 6.5 pM-l s-l, respectively.
The proteolytic coefficient is of the same order of magnitude as those obtained for other milk-clotting
enzymes, but the k, is significantly lower, which reflects the higher affinity of Cynara protease to
K-casei
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