689 research outputs found
Rlp7p is associated with 60S preribosomes, restricted to the granular component of the nucleolus, and required for pre-rRNA processing
Many analyses have examined subnucleolar structures in eukaryotic cells, but the relationship between morphological structures, pre-rRNA processing, and ribosomal particle assembly has remained unclear. Using a visual assay for export of the 60S ribosomal subunit, we isolated a ts-lethal mutation, rix9-1, which causes nucleolar accumulation of an Rpl25p-eGFP reporter construct. The mutation results in a single amino acid substitution (F(176)S) in Rlp7p, an essential nucleolar protein related to ribosomal protein Rpl7p. The rix9-1 (rlp7-1) mutation blocks the late pre-RNA cleavage at site C(2) in ITS2, which separates the precursors to the 5.8S and 25S rRNAs. Consistent with this, synthesis of the mature 5.8S and 25S rRNAs was blocked in the rlp7-1 strain at nonpermissive temperature, whereas 18S rRNA synthesis continued. Moreover, pre-rRNA containing ITS2 accumulates in the nucleolus of rix9-1 cells as revealed by in situ hybridization. Finally, tagged Rlp7p was shown to associate with a pre-60S particle, and fluorescence microscopy and immuno-EM localized Rlp7p to a subregion of the nucleolus, which could be the granular component (GC). All together, these data suggest that pre-rRNA cleavage at site C(2) specifically requires Rlp7p and occurs within pre-60S particles located in the GC region of the nucleolus
Nonuniversal Effects in the Homogeneous Bose Gas
Effective field theory predicts that the leading nonuniversal effects in the
homogeneous Bose gas arise from the effective range for S-wave scattering and
from an effective three-body contact interaction. We calculate the leading
nonuniversal contributions to the energy density and condensate fraction and
compare the predictions with results from diffusion Monte Carlo calculations by
Giorgini, Boronat, and Casulleras. We give a crude determination of the
strength of the three-body contact interaction for various model potentials.
Accurate determinations could be obtained from diffusion Monte Carlo
calculations of the energy density with higher statistics.Comment: 24 pages, RevTex, 5 ps figures, included with epsf.te
"The trauma of competition": the entry of Air Products Inc. into the industrial gases business in Britain and continental Europe 1947-1970
The British Oxygen Company (BOC) had a virtual monopoly on the supply of industrial gases (e.g. oxygen and acetylene) on the British market through the 1950s, when it was finally challenged by an American-based company, Air Products. Air Products Limited (APL) was able to undercut BOCs position, overcoming high barriers to entry to gain significant market share in this sector, which shares some features of network industries. Factors in this success included conditions imposed by the Board of Trade, APLâs innovations, BOCâs slow response, and favourable market conditions. APLâs success had implications for the internationalisation of the industrial gases industry
Lattice diffusion and surface segregation of B during growth of SiGe heterostructures by molecular beam epitaxy: effect of Ge concentration and biaxial stress
Si1-xGex/Si1-yGey/Si(100) heterostructures grown by Molecular Beam Epitaxy
(MBE) were used in order to study B surface segregation during growth and B
lattice diffusion. Ge concentration and stress effects were separated. Analysis
of B segregation during growth shows that: i) for layers in epitaxy on
(100)Si), B segregation decreases with increasing Ge concentration, i.e. with
increased compressive stress, ii) for unstressed layers, B segregation
increases with Ge concentration, iii) at constant Ge concentration, B
segregation increases for layers in tension and decreases for layers in
compression. The contrasting behaviors observed as a function of Ge
concentration in compressively stressed and unstressed layers can be explained
by an increase of the equilibrium segregation driving force induced by Ge
additions and an increase of near-surface diffusion in compressively stressed
layers. Analysis of lattice diffusion shows that: i) in unstressed layers, B
lattice diffusion coefficient decreases with increasing Ge concentration, ii)
at constant Ge concentration, the diffusion coefficient of B decreases with
compressive biaxial stress and increases with tensile biaxial stress, iii) the
volume of activation of B diffusion () is positive for biaxial stress while it
is negative in the case of hydrostatic pressure. This confirms that under a
biaxial stress the activation volume is reduced to the relaxation volume
T cell-mediated immunity to Cowdria ruminantium in mice : the protective role of Lyt-2âș T cells
The inability of athymic nude mice to make a drug-aided recovery from infection with either the KĂŒmm or the Welgevonden stocks of Cowdria ruminantium and their inability to mount an immune response, suggest that immunity in heartwater is cell-mediated. The adoptive transfer of immunity with the spleen cells of mice immune to the Welgevonden stock is supportive evidence. Immune spleen cells depleted of Lyt-2âș T cells are unable to confer resistance to challenge to recipient mice, whereas the depletion of LâTââș T cells had no effect on the protection conferred by immune spleen cells. This is conclusive evidence that immunity in heartwater is largely cell-mediated. Immune serum, C. ruminantium and complement incubated in the presence of mouse peritoneal macrophages, inhibits the infectivity of the heartwater agent, but not in the absence of macrophages. The decreased resistance to challenge of immune mice treated with gloxazone adds further support to the concept that in heartwater persistence of C. ruminantium in the host is associated with immunity.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201
Application of short time energy analysis in monitoring the stability of arc sound signal
This paper employed the short time energy of arc sound signals to online quantitatively describe the stability of arc sound signal. At first the signal can be preprocessed by wavelet packet filtering and then detailed information of the short time energy of the signal was obtained using hamming window. After statistical analyzed the short time energy the energy distribution possibility and cumulative distribution function of the signal can be collected. Then a proposed stability evaluation criterion was employed to quantitatively describe the stability of arc sound signal. Relative experimental data showed that more stable signal corresponded lager value of the criterion. The proposed method which combined the short time energy and statistical analysis was supported by many actual experiments. This contribution can benefit the quantitative evaluation of the arc welding process and instructed the future parameters optimization to obtain welding products with high quality. (C) 2017 Elsevier Ltd. All rights reserved
Coexistence of Anomalous Hall Effect and Weak Net Magnetization in Collinear Antiferromagnet MnTe
Anomalous Hall effect (AHE) plays important role in the rapidly developing
field of antiferromagnetic spintronics. It has been recently discussed that it
can be a feature of not only uncompensated magnetic systems but also in
altermagnetic materials. Hexagonal MnTe belongs to this appealing group of
compounds exhibiting AHE and is commonly perceived as magnetically compensated.
Here, we demonstrate that bulk form of MnTe exhibits small but detectable
magnetic moment correlating with hysteretic behaviour of the AHE. We formulate
a phenomenological model which explains how this feature allows to create a
disbalance between states with opposite N\'eel vector and prevent the AHE
signal from averaging out to zero. Moreover, we show how the dependence of AHE
on the N\'eel vector arises on microscopical level and highlight the
differences in Berry curvature between magnetically compensated and
uncompensated systems
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