858 research outputs found
Phase diagram for morphological transitions of wetting films on chemically structured substrates
Using an interface displacement model we calculate the shapes of thin
liquidlike films adsorbed on flat substrates containing a chemical stripe. We
determine the entire phase diagram of morphological phase transitions in these
films as function of temperature, undersaturation, and stripe widthComment: 15 pages, RevTeX, 7 Figure
Identification and characterization of a novel Geobacillus thermoglucosidasius bacteriophage, GVE3
The study of extremophilicphages may reveal new phage families as well as different mechanisms of infection,
propagation and lysis to those found in phages from temperate environments. We describe a novel siphovirus,
GVE3, that infects the thermophileGeobacillusthermoglucosidasius. The genome size is 141298 bp(G+C
29.6%) making it the largest Geobacillusspp infecting phage known.GVE3 appears to be most closely related to
the recently described Bacillus anthracis phage vB_BanS_Tsamsa, rather thanGeobacillus infecting phages
described thus far.Tetranucleotide usage deviation analysis supports this relationship, showing that the GVE3
genome sequence correlates best with B. anthracis and Bacillus cereus genome sequences, rather than
Geobacillusspp genome sequences.National Research Foundation (NRF) of South Africahttp://link.springer.com/journal/7052016-09-30hb201
Engineering pyruvate decarboxylase-mediated ethanol production in the thermophilic host Geobacillus thermoglucosidasius
This study reports the expression, purification and kinetic characterization of a PDC from
Gluconobacter oxydans. Kinetic analyses showed the enzyme to have high affinity for pyruvate
(120ÎŒM at pH 5), high catalytic efficiency (4.75 x 105 M-1s-1 at pH 5), a pHopt of approximately
4.5 and an in vitro temperature optimum at approximately 55°C (the highest yet reported for a
bacterial PDC). Due to good in vitro thermostablity (approximately 40% enzyme activity
retained after 30 minutes at 65°C) this PDC was considered to be a suitable candidate for
heterologous expression in the thermophile Geobacillus thermoglucosidasius. Initial studies
using a variety of methods failed to detect activity at any growth temperature. However, the
application of codon harmonization (i.e., mimicry of the heterogeneous hostâs transcription and
translational rhythm) yielded a protein that was fully functional in the thermophilic strain at
45°C (as determined by enzyme activity, Western blot, mRNA detection and ethanol productivity). Here we describe the successful expression of PDC in a true thermophile. Yields
as high as 0.35 g/g ±0.04 ethanol per gram of glucose consumed were detected, highly
competitive to those reported in ethanologenic thermophilic mutants. Although activities could
not be detected at temperatures approaching the growth optimum for the strain, this study
highlights that the possibility that previously unsuccessful expression of pdcs in Geobacillus spp.
may be the result of ineffective transcription / translation coupling.National Research Foundation South Africahttp://link.springer.com/journal/253hb201
Cross-domain interference costs during concurrent verbal and spatial serial memory tasks are asymmetric
Some evidence suggests that memory for serial order is domain-general. Evidence also points to asymmetries in interference between verbal and visual-spatial tasks. We confirm that concurrently remembering verbal and spatial serial lists provokes substantial interference compared with remembering a single list, but we further investigate the impact of this interference throughout the serial position curve, where asymmetries are indeed apparent. A concurrent verbal order memory task affects spatial memory performance throughout the serial positions of the list, but performing a spatial order task affects memory for the verbal serial list only for early list items; in the verbal task only, the final items are unaffected by a concurrent task. Adding suffixes eliminates this asymmetry, resulting in impairment throughout the list for both tasks. These results suggest that domain-general working memory resources may be supplemented with resources specific to the verbal domain, but perhaps not with equivalent spatial resources
Possible origins of macroscopic left-right asymmetry in organisms
I consider the microscopic mechanisms by which a particular left-right (L/R)
asymmetry is generated at the organism level from the microscopic handedness of
cytoskeletal molecules. In light of a fundamental symmetry principle, the
typical pattern-formation mechanisms of diffusion plus regulation cannot
implement the "right-hand rule"; at the microscopic level, the cell's
cytoskeleton of chiral filaments seems always to be involved, usually in
collective states driven by polymerization forces or molecular motors. It seems
particularly easy for handedness to emerge in a shear or rotation in the
background of an effectively two-dimensional system, such as the cell membrane
or a layer of cells, as this requires no pre-existing axis apart from the layer
normal. I detail a scenario involving actin/myosin layers in snails and in C.
elegans, and also one about the microtubule layer in plant cells. I also survey
the other examples that I am aware of, such as the emergence of handedness such
as the emergence of handedness in neurons, in eukaryote cell motility, and in
non-flagellated bacteria.Comment: 42 pages, 6 figures, resubmitted to J. Stat. Phys. special issue.
Major rewrite, rearranged sections/subsections, new Fig 3 + 6, new physics in
Sec 2.4 and 3.4.1, added Sec 5 and subsections of Sec
La ricerca in Psicologia Clinica Perinatale : fattori di rischio e protezione per la tutela della salute mentale
Search for the glueball candidates f0(1500) and fJ(1710) in gamma gamma collisions
Data taken with the ALEPH detector at LEP1 have been used to search for gamma
gamma production of the glueball candidates f0(1500) and fJ(1710) via their
decay to pi+pi-. No signal is observed and upper limits to the product of gamma
gamma width and pi+pi- branching ratio of the f0(1500) and the fJ(1710) have
been measured to be Gamma_(gamma gamma -> f0(1500)). BR(f0(1500)->pi+pi-) <
0.31 keV and Gamma_(gamma gamma -> fJ(1710)). BR(fJ(1710)->pi+pi-) < 0.55 keV
at 95% confidence level.Comment: 10 pages, 3 figure
Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV
A search for pair-production of supersymmetric particles under the assumption
that R-parity is violated via a dominant LQDbar coupling has been performed
using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV.
The observed candidate events in the data are in agreement with the Standard
Model expectation. This result is translated into lower limits on the masses of
charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for
m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81
GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the
95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
Measurement of the branching fraction
The branching fraction is measured in a data sample
corresponding to 0.41 of integrated luminosity collected with the LHCb
detector at the LHC. This channel is sensitive to the penguin contributions
affecting the sin2 measurement from The
time-integrated branching fraction is measured to be . This is the most precise measurement to
date
Model-independent search for CP violation in D0âKâK+ÏâÏ+ and D0âÏâÏ+Ï+Ïâ decays
A search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states KâK+ÏâÏ+ and ÏâÏ+Ï+Ïâ is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fbâ1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the KâK+ÏâÏ+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the ÏâÏ+Ï+Ïâ final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity
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