2,512 research outputs found
Novel Viruses of the Family Partitiviridae Discovered in Saccharomyces cerevisiae
It has been 49 years since the last discovery of a new virus family in the model yeast Saccharomyces cerevisiae. A large-scale screen to determine the diversity of double-stranded RNA (dsRNA) viruses in S. cerevisiae has identified multiple novel viruses from the family Partitiviridae that have been previously shown to infect plants, fungi, protozoans, and insects. Most S. cerevisiae partitiviruses (ScPVs) are associated with strains of yeasts isolated from coffee and cacao beans. The presence of partitiviruses was confirmed by sequencing the viral dsRNAs and purifying and visualizing isometric, non-enveloped viral particles. ScPVs have a typical bipartite genome encoding an RNA-dependent RNA polymerase (RdRP) and a coat protein (CP). Phylogenetic analysis of ScPVs identified three species of ScPV, which are most closely related to viruses of the genus Cryspovirus from the mammalian pathogenic protozoan Cryptosporidium parvum. Molecular modeling of the ScPV RdRP revealed a conserved tertiary structure and catalytic site organization when compared to the RdRPs of the Picornaviridae. The ScPV CP is the smallest so far identified in the Partitiviridae and has structural homology with the CP of other partitiviruses but likely lacks a protrusion domain that is a conspicuous feature of other partitivirus particles. ScPVs were stably maintained during laboratory growth and were successfully transferred to haploid progeny after sporulation, which provides future opportunities to study partitivirus-host interactions using the powerful genetic tools available for the model organism S. cerevisiae
Young peoplesâ reflections on what teachers think about family obligations that conflict with school: A focus on the non-normative roles of young caring and language brokering
In âWesternâ contexts school attendance is central for an âidealâ childhood. However, many young people engage with home roles that conflict with school expectations. This paper explores perceptions of that process in relation two home activities - language brokering and young caring. We interviewed 46 young people and asked them to reflect on what the teacher would think when a child had to miss school to help a family member. This paper discusses the young peopleâs overall need to keep their out-of-school lives private from their teachers
The envelope of IRC+10216 reflecting the galactic light: UBV surface brightness photometry and interpretation
We present and analyse new optical images of the dust envelope surrounding
the high mass-loss carbon star IRC+10216. This envelope is seen due to external
illumination by galactic light. Intensity profiles and colors of the nebula
were obtained in the UBV bandpasses. The data are compared with the results of
a radiative transfer model calculating multiple scattering of interstellar
field photons by dust grains with a single radius. The data show that the
observed radial shape of the nebula, especially its half maximum radius, does
not depend on wavelength (within experimental errors), suggesting that grains
scatter in the grey regime, etc, etc (this abstract has been shortened)Comment: accepted by A
A method for isolating and culturing placental cells from failed early equine pregnancies
Early pregnancy loss occurs in 6â10% of equine pregnancies making it the main cause of reproductive wastage. Despite this, reasons for the losses are known in only 16% of cases. Lack of viable conceptus material has inhibited investigations of many potential genetic and pathological causes. We present a method for isolating and culturing placental cells from failed early equine pregnancies. Trophoblast cells from 18/30 (60%) failed equine pregnancies of gestational ages 14â65 days were successfully cultured in three different media, with the greatest growth achieved for cells cultured in AmnioChromeâą Plus. Genomic DNA of a suitable quality for molecular assays was also isolated from 29/30 of these cases. This method will enable future investigations determining pathologies causing EPL
Role of twin boundaries on the vortex dynamics in YBaCuO
By means of a novel technique of rotating the applied current we have
directly measured the influence of twin boundaries on the vortex motion in a
YBaCuO single crystal. The results indicate that the effect of twin
planes on the vortex dynamics starts to develop below a certain temperature,
being responsible for an anisotropic viscosity in the vortex liquid state and a
guided motion in the solid state.Comment: 4 pages, 4 figure
Vortex Lattices in Quantum Mechanics
Vortex lattices are constructed in terms of linear combinations of solutions
for Scr\"{o}dinger equation with a constant potential. The vortex lattices are
mapped on the spaces with two-dimensional rotationally symmetric potentials by
using conformal mappings and the differences of the mapped vortex-patterns are
examined. The existence of vortex dipole and quadrupole is also pointed out.Comment: 13 page
Dynamics of electrostatically-driven granular media. Effects of Humidity
We performed experimental studies of the effect of humidity on the dynamics
of electrostatically-driven granular materials. Both conducting and dielectric
particles undergo a phase transition from an immobile state (granular solid) to
a fluidized state (granular gas) with increasing applied field. Spontaneous
precipitation of solid clusters from the gas phase occurs as the external
driving is decreased. The clustering dynamics in conducting particles is
primarily controlled by screening of the electric field but is aided by
cohesion due to humidity. It is shown that humidity effects dominate the
clustering process with dielectric particles.Comment: 4 pages, 4 fig
Internal avalanches in a pile of superconducting vortices
Using an array of miniature Hall probes, we monitored the spatiotemporal
variation of the internal magnetic induction in a superconducting niobium
sample during a slow sweep of external magnetic field. We found that a sizable
fraction of the increase in the local vortex population occurs in abrupt jumps.
The size distribution of these avalanches presents a power-law collapse on a
limited range. In contrast, at low temperatures and low fields, huge avalanches
with a typical size occur and the system does not display a well-defined
macroscopic critical current.Comment: 5 pages including 5 figure
Investigating the Cosmic-Ray Ionization Rate in the Galactic Diffuse Interstellar Medium through Observations of H3+
Observations of H3+ in the Galactic diffuse interstellar medium (ISM) have
led to various surprising results, including the conclusion that the cosmic-ray
ionization rate (zeta_2) is about 1 order of magnitude larger than previously
thought. The present survey expands the sample of diffuse cloud sight lines
with H3+ observations to 50, with detections in 21 of those. Ionization rates
inferred from these observations are in the range (1.7+-1.3)x10^-16
s^-1<zeta_2<(10.6+-8.2)x10^-16 s^-1 with a mean value of
zeta_2=(3.5^+5.3_-3.0)x10^-16 s^-1. Upper limits (3 sigma) derived from
non-detections of H3+ are as low as zeta_2<0.4x10^-16 s^-1. These low
upper-limits, in combination with the wide range of inferred cosmic-ray
ionization rates, indicate variations in zeta_2 between different diffuse cloud
sight lines. A study of zeta_2 versus N_H (total hydrogen column density) shows
that the two parameters are not correlated for diffuse molecular cloud sight
lines, but that the ionization rate decreases when N_H increases to values
typical of dense molecular clouds. Both the difference in ionization rates
between diffuse and dense clouds and the variation of zeta_2 among diffuse
cloud sight lines are likely the result of particle propagation effects. The
lower ionization rate in dense clouds is due to the inability of low-energy
(few MeV) protons to penetrate such regions, while the ionization rate in
diffuse clouds is controlled by the proximity of the observed cloud to a site
of particle acceleration.Comment: 48 pages, 19 figures, 4 tables, accepted for publication in Ap
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