464 research outputs found
Predatory Organisms with Untapped Biosynthetic Potential:Descriptions of Novel Corallococcus Species C. aberystwythensis sp. nov., C. carmarthensis sp. nov., C. exercitus sp. nov., C. interemptor sp. nov., C. llansteffanensis sp. nov., C. praedator sp. nov., C. sicarius sp. nov., and C. terminator sp. nov
Corallococcus spp. are common soil-dwelling organisms which kill and consume prey microbes through the secretion of antimicrobial substances. Two species of Corallococcus have been described previously (Corallococcus coralloides and Corallococcus exiguus).
A polyphasic approach was taken to characterise antimicrobial, biochemical and phenotypic properties of eight Corallococcus spp. strains and the two type strains. We also report here the genome sequence of the C. exiguus type strain (DSM 14696T).
The genomes of the eight candidate strains, C. exiguus DSM 14696T and C. coralloides DSM 2259T, had an average nucleotide identity below 95% and digital DNA-DNA hybridisation scores less than the 70% lower bound for species identity, indicating they belong to distinct species.
All ten strains, including the two type strains, were thoroughly characterised, including biochemical analysis of their fatty acid methyl esters, substrate utilisation and sugar assimilation. Each strain gave a distinct profile of properties, which together with their genomic differences supports the proposal of the eight candidate strains as novel species: Corallococcus exercitus sp. nov. (AB043AT = DSM 108849T = NBRC 113887T), Corallococcus interemptor sp. nov. (AB047AT = DSM 108843T = NBRC 113888T), Corallococcus aberystwythensis sp. nov. (AB050AT = DSM 108846T = NBRC 114019T), Corallococcus praedator sp. nov. (CA031BT = DSM 108841T = NBRC 113889T), Corallococcus sicarius sp. nov. (CA040BT = DSM 108850T = NBRC 113890T), Corallococcus carmarthenensis sp. nov. (CA043DT = DSM 108842T = NBRC 113891T), Corallococcus llansteffanensis sp. nov. (CA051BT = DSM 108844T = NBRC 114100T) and Corallococcus terminator sp. nov. (CA054AT = DSM 108848T = NBRC 113892T)
Magnetic Field Strength in the Upper Solar Corona Using White-light Shock Structures Surrounding Coronal Mass Ejections
To measure the magnetic field strength in the solar corona, we examined 10
fast (> 1000 km/s) limb CMEs which show clear shock structures in SOHO/LASCO
images. By applying piston-shock relationship to the observed CME's standoff
distance and electron density compression ratio, we estimated the Mach number,
Alfven speed, and magnetic field strength in the height range 3 to 15 solar
radii (Rs). Main results from this study are: (1) the standoff distance
observed in solar corona is consistent with those from a magnetohydrodynamic
(MHD) model and near-Earth observations; (2) the Mach number as a shock
strength is in the range 1.49 to 3.43 from the standoff distance ratio, but
when we use the density compression ratio, the Mach number is in the range 1.47
to 1.90, implying that the measured density compression ratio is likely to be
underestimated due to observational limits; (3) the Alfven speed ranges from
259 to 982 km/s and the magnetic field strength is in the range 6 to 105 mG
when the standoff distance is used; (4) if we multiply the density compression
ratio by a factor of 2, the Alfven speeds and the magnetic field strengths are
consistent in both methods; (5) the magnetic field strengths derived from the
shock parameters are similar to those of empirical models and previous
estimates.Comment: Accepted for publication in ApJ, 11 Figures, 1 Tabl
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Ensemble prediction for nowcasting with a convection-permitting model - II: forecast error statistics
A 24-member ensemble of 1-h high-resolution forecasts over the Southern United Kingdom is used to study short-range forecast error statistics. The initial conditions are found from perturbations from an ensemble transform Kalman filter. Forecasts from this system are assumed to lie within the bounds of forecast error of an operational forecast system. Although noisy, this system is capable of producing physically reasonable statistics which are analysed and compared to statistics implied from a variational assimilation system. The variances for temperature errors for instance show structures that reflect convective activity. Some variables, notably potential temperature and specific humidity perturbations, have autocorrelation functions that deviate from 3-D isotropy at the convective-scale (horizontal scales less than 10 km). Other variables, notably the velocity potential for horizontal divergence perturbations, maintain 3-D isotropy at all scales. Geostrophic and hydrostatic balances are studied by examining correlations between terms in the divergence and vertical momentum equations respectively. Both balances are found to decay as the horizontal scale decreases. It is estimated that geostrophic balance becomes less important at scales smaller than 75 km, and hydrostatic balance becomes less important at scales smaller than 35 km, although more work is required to validate these findings. The implications of these results for high-resolution data assimilation are discussed
The Far-Ultraviolet "Continuum" in Protoplanetary Disk Systems II: CO Fourth Positive Emission and Absorption
We exploit the high sensitivity and moderate spectral resolution of the
-Cosmic Origins Spectrograph to detect far-ultraviolet spectral features
of carbon monoxide (CO) present in the inner regions of protoplanetary disks
for the first time. We present spectra of the classical T Tauri stars HN Tau,
RECX-11, and V4046 Sgr, representative of a range of CO radiative processes. HN
Tau shows CO bands in absorption against the accretion continuum. We measure a
CO column density and rotational excitation temperature of N(CO) = 2 +/- 1
10 cm and T_rot(CO) 500 +/- 200 K for the absorbing gas.
We also detect CO A-X band emission in RECX-11 and V4046 Sgr, excited by
ultraviolet line photons, predominantly HI LyA. All three objects show emission
from CO bands at 1560 \AA, which may be excited by a combination
of UV photons and collisions with non-thermal electrons. In previous
observations these emission processes were not accounted for due to blending
with emission from the accretion shock, collisionally excited H, and
photo-excited H2; all of which appeared as a "continuum" whose components could
not be separated. The CO emission spectrum is strongly dependent upon the shape
of the incident stellar LyA emission profile. We find CO parameters in the
range: N(CO) 10 cm, T_{rot}(CO) > 300 K for the LyA-pumped
emission. We combine these results with recent work on photo- and
collisionally-excited H emission, concluding that the observations of
ultraviolet-emitting CO and H2 are consistent with a common spatial origin. We
suggest that the CO/H2 ratio in the inner disk is ~1, a transition between the
much lower interstellar value and the higher value observed in solar system
comets today, a result that will require future observational and theoretical
study to confirm.Comment: 12 pages, 7 figures, 3 tables. ApJ - accepte
Ethnographic perspectives on global mental health
The field of Global Mental Health (GMH) aims to influence mental health policy and practice worldwide, with a focus on human rights and access to care. There have been important achievements, but GMH has also been the focus of scholarly controversies arising from political, cultural and pragmatic critiques. These debates have become increasingly polarized, giving rise to a need for more dialogue and experience-near research to inform theorizing. Ethnography has much to offer in this respect. This paper frames and introduces five articles in the issue of Transcultural Psychiatry that illustrate the role of ethnographic methods in understanding the effects and implications of the field of global mental health on mental health policy and practice. The papers include ethnographies from South Africa, India and Tonga, that show the potential for ethnographic evidence to inform GMH projects. These studies provide nuanced conceptualizations of GMHâs varied manifestations across different settings, the diverse ways that GMHâs achievements can be evaluated, and the connections that can be drawn between locally observed experiences and wider historical, political and social phenomena. Ethnography can provide a basis for constructive dialogue between those engaged in developing and implementing GMH interventions and those critical of some of its approaches
âWe donât just do what weâre told to do!â Exploring pedagogical technology development needs
Confirmation of a Faraday Rotation Measure Anomaly in Cygnus
We confirm the reality of a reversal of the sign of the Faraday Rotation
Measure in the Galactic plane in Cygnus (Lazio et al, 1990), possibly
associated with the Cygnus OB1 association. The rotation measure changes by
several hundred rad/m over an angular scale of . We show that
a simple model of an expanding plasma shell with an enhanced density and
magnetic field, consistent with observations of H emission in this part
of sky, and physically associated with a superbubble of the Cygnus OB1
association, can account for the magnitude and angular scale of this feature.Comment: Submitted to the Astrophysical Journa
Photoevaporation as a Truncation Mechanism for Circumplanetary Disks
We investigate the conditions under which the regular satellites of Jupiter
and Saturn formed. The final stage of giant planet accretion is thought to
occur slowly over a relatively long, 10 Myr, timescale. Gas accretion during
this stage, through a completely or partially opened gap in the solar nebula,
occurs slowly allowing for the condensation of ices, and incomplete
differentiation, seen in the regular satellites of the giant planets.
Furthermore, the dichotomy seen in the Jovian and Saturnian systems may be
explained as this infall wanes or is completely shutoff as a result of gap
opening or global depletion of gas in the solar nebula. We present
one-dimensional simulations of circumplanetary disks that couple the viscous
transport of material with the loss of mass at the disk outer edge by
ultraviolet photoevaporation as well as the infall of material from the solar
nebula. We find that the circumplanetary disks of these protoplanets are
truncated, as a result of photoevaporation, at a range of values with the mean
corresponding to 0.16 Hill radii. These truncation radii are broadly
consistent with the current locations of the regular satellite systems of
Jupiter and Saturn. We also find that photoevaporation can successfully act as
a clearing mechanism for circumplanetary nebulae on the potentially short
timescales, 100-10,000 yr, over which mass accretion from the solar nebula
wanes as a result of gap opening. Such a rapid clearing of the circum-Jovian
disk may be required to explain the survival of the Galilean satellites.Comment: 6 pages, 6 figures, accepted for publication in the Astronomical
Journa
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