2,533 research outputs found
Influence of mixed culture system on the growth performance of Aspergillus oryzae and Saccharomyces cerevisiae
This study describes a novel strategy to improve the α-galactosidase and invertase production of Saccharomyces cerevisiae by co-cultivating it with Aspergillus oryzae. In the mixed culture, the growth of the both strains was repressed, and the protein synthesis for the yeast cell wall was promoted significantly. As a result, α-galactosidase and invertase activities of the mixed culture reached 85.16 and 561.60 Uml-1, over 9 and 15 fold greater than the values obtained in the cultures of single strain, respectively. During the simultaneous saccharification and fermentation procedure, ethanol with the concentration of 15.2% (v/v) was obtained from soybean sirup in 60 h at 30°C, and the conversion efficiency of total sugar to ethanol was 96.3% of the theoretical ethanol yield.Keywords: Co-cultivation, Aspergillus oryzae, Saccharomyces cerevisiae, α-galactosidase, invertaseAfrican Journal of Biotechnology Vol. 12(21), pp. 3272-327
Acoustic black holes for relativistic fluids
We derive a new acoustic black hole metric from the Abelian Higgs model. In
the non-relativistic limit, while the Abelian Higgs model becomes the
Ginzburg-Landau model, the metric reduces to an ordinary Unruh type. We
investigate the possibility of using (type I and II) superconductors as the
acoustic black holes. We propose to realize experimental acoustic black holes
by using spiral vortices solutions from the Navier-stokes equation in the
non-relativistic classical fluids.Comment: 16 pages. typos corrected, contents expande
Risk of Dengue for Tourists and Teams during the World Cup 2014 in Brazil
Abstract:Background:This year, Brazil will host about 600,000 foreign visitors during the 2014 FIFA World Cup. The concern of possible dengue transmission during this event has been raised given the high transmission rates reported in the past by this country.Methodology/Principal Findings:We used dengue incidence rates reported by each host city during previous years (2001-2013) to estimate the risk of dengue during the World Cup for tourists and teams. Two statistical models were used: a percentile rank (PR) and an Empirical Bayes (EB) model. Expected IR's during the games were generally low (<10/100,000) but predictions varied across locations and between models. Based on current ticket allocations, the mean number of expected symptomatic dengue cases ranged from 26 (PR, 10th-100th percentile: 5-334 cases) to 59 (EB, 95% credible interval: 30-77 cases) among foreign tourists but none are expected among teams. These numbers will highly depend on actual travel schedules and dengue immunity among visitors. Sensitivity analysis for both models indicated that the expected number of cases could be as low as 4 or 5 with 100,000 visitors and as high as 38 or 70 with 800,000 visitors (PR and EB, respectively).Conclusion/Significance:The risk of dengue among tourists during the World Cup is expected to be small due to immunity among the Brazil host population provided by last year's epidemic with the same DENV serotypes. Quantitative risk estimates by different groups and methodologies should be made routinely for mass gathering events. © 2014 van Panhuis et al
Quantum catastrophe of slow light
Catastrophes are at the heart of many fascinating optical phenomena. The
rainbow, for example, is a ray catastrophe where light rays become infinitely
intense. The wave nature of light resolves the infinities of ray catastrophes
while drawing delicate interference patterns such as the supernumerary arcs of
the rainbow. Black holes cause wave singularities. Waves oscillate with
infinitely small wave lengths at the event horizon where time stands still. The
quantum nature of light avoids this higher level of catastrophic behaviour
while producing a quantum phenomenon known as Hawking radiation. As this letter
describes, light brought to a standstill in laboratory experiments can suffer a
similar wave singularity caused by a parabolic profile of the group velocity.
In turn, the quantum vacuum is forced to create photon pairs with a
characteristic spectrum. The idea may initiate a theory of quantum
catastrophes, in addition to classical catastrophe theory, and the proposed
experiment may lead to the first direct observation of a phenomenon related to
Hawking radiation.Comment: Published as "A laboratory analogue of the event horizon using slow
light in an atomic medium
The entangling side of the Unruh-Hawking effect
We show that the Unruh effect can create net quantum entanglement between
inertial and accelerated observers depending on the choice of the inertial
state. This striking result banishes the extended belief that the Unruh effect
can only destroy entanglement and furthermore provides a new and unexpected
source for finding experimental evidence of the Unruh and Hawking effects.Comment: 4 pages, 4 figures. Added Journal referenc
Condensed matter lessons about the origin of time
It is widely hoped that quantum gravity will shed light on the question of
the origin of time in physics. The currently dominant approaches to a candidate
quantum theory of gravity have naturally evolved from general relativity, on
the one hand, and from particle physics, on the other hand. A third important
branch of 20th century `fundamental' physics, condensed-matter physics, also
offers an interesting perspective on quantum gravity, and thereby on the
problem of time. The bottomline might sound disappointing: to understand the
origin of time, much more experimental input is needed than what is available
today. Moreover it is far from obvious that we will ever find out the true
origin of physical time, even if we become able to directly probe physics at
the Planck scale. But we might learn some interesting lessons about time and
the structure of our universe in the process. A first lesson is that there are
probably several characteristic scales associated with "quantum gravity"
effects, rather than the single Planck scale usually considered. These can
differ by several orders of magnitude, and thereby conspire to hide certain
effects expected from quantum gravity, rendering them undetectable even with
Planck-scale experiments. A more tentative conclusion is that the hierarchy
between general relativity, special relativity and Newtonian physics, usually
taken for granted, might have to be interpreted with caution.Comment: v1: 9 pages. Fourth juried prize in FQXi essay contest on "the Nature
of Time" (2008). v2: 2015 update, partially rewritten and extended for
Foundations of Physics. arXiv admin note: substantial text overlap with
arXiv:0810.061
Ribosomal oxygenases are structurally conserved from prokaryotes to humans
2-Oxoglutarate (2OG)-dependent oxygenases have important roles in the regulation of gene expression via demethylation of N-methylated chromatin components1,2 and in the hydroxylation of transcription factors3 and splicing factor proteins4. Recently, 2OG-dependent oxygenases that catalyse hydroxylation of transfer RNA5,6,7 and ribosomal proteins8 have been shown to be important in translation relating to cellular growth, TH17-cell differentiation and translational accuracy9,10,11,12. The finding that ribosomal oxygenases (ROXs) occur in organisms ranging from prokaryotes to humans8 raises questions as to their structural and evolutionary relationships. In Escherichia coli, YcfD catalyses arginine hydroxylation in the ribosomal protein L16; in humans, MYC-induced nuclear antigen (MINA53; also known as MINA) and nucleolar protein 66 (NO66) catalyse histidine hydroxylation in the ribosomal proteins RPL27A and RPL8, respectively. The functional assignments of ROXs open therapeutic possibilities via either ROX inhibition or targeting of differentially modified ribosomes. Despite differences in the residue and protein selectivities of prokaryotic and eukaryotic ROXs, comparison of the crystal structures of E. coli YcfD and Rhodothermus marinus YcfD with those of human MINA53 and NO66 reveals highly conserved folds and novel dimerization modes defining a new structural subfamily of 2OG-dependent oxygenases. ROX structures with and without their substrates support their functional assignments as hydroxylases but not demethylases, and reveal how the subfamily has evolved to catalyse the hydroxylation of different residue side chains of ribosomal proteins. Comparison of ROX crystal structures with those of other JmjC-domain-containing hydroxylases, including the hypoxia-inducible factor asparaginyl hydroxylase FIH and histone Nε-methyl lysine demethylases, identifies branch points in 2OG-dependent oxygenase evolution and distinguishes between JmjC-containing hydroxylases and demethylases catalysing modifications of translational and transcriptional machinery. The structures reveal that new protein hydroxylation activities can evolve by changing the coordination position from which the iron-bound substrate-oxidizing species reacts. This coordination flexibility has probably contributed to the evolution of the wide range of reactions catalysed by oxygenases
The FGLamide-Allatostatins Influence Foraging Behavior in Drosophila melanogaster
Allatostatins (ASTs) are multifunctional neuropeptides that generally act in an inhibitory fashion. ASTs were identified as inhibitors of juvenile hormone biosynthesis. Juvenile hormone regulates insect metamorphosis, reproduction, food intake, growth, and development. Drosophila melanogaster RNAi lines of PheGlyLeu-amide-ASTs (FGLa/ASTs) and their cognate receptor, Dar-1, were used to characterize roles these neuropeptides and their respective receptor may play in behavior and physiology. Dar-1 and FGLa/AST RNAi lines showed a significant reduction in larval foraging in the presence of food. The larval foraging defect is not observed in the absence of food. These RNAi lines have decreased for transcript levels which encodes cGMP- dependent protein kinase. A reduction in the for transcript is known to be associated with a naturally occuring allelic variation that creates a sitter phenotype in contrast to the rover phenotype which is caused by a for allele associated with increased for activity. The sitting phenotype of FGLa/AST and Dar-1 RNAi lines is similar to the phenotype of a deletion mutant of an AST/galanin-like receptor (NPR-9) in Caenorhabditis elegans. Associated with the foraging defect in C. elegans npr-9 mutants is accumulation of intestinal lipid. Lipid accumulation was not a phenotype associated with the FGLa/AST and Dar-1 RNAi lines
Oh, Jeremy Corbyn! Why did Labour Party membership soar after the 2015 general election?
This article investigates the remarkable surge in individual membership of the Labour Party after the general election of May 2015, particularly after Jeremy Corbyn was officially nominated as a candidate for the leadership in June of that year. Using both British Election Study and Party Members Project data, we explain the surge by focussing on the attitudinal, ideological and demographic characteristics of the members themselves. Findings suggest that, along with support for the leader and yearning for a new style of politics, feelings of relative deprivation played a significant part: many ‘left-behind’ voters (some well-educated, some less so) joined Labour for the first time when a candidate with a clearly radical profile appeared on the leadership ballot. Anti-capitalist and left-wing values mattered too, particularly for those former members who decided to return to the party
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