148 research outputs found
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The appointment of insolvency practitioners in South Africa: time for change
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4:3:2:1... Fair distribution of appointments or countdown to catastrophe? South Africa’s ministerial policy for the appointment of liquidators under the spotlight
Long-Term Storage Quality of Table Grapes as Influenced by Pre-Harvest Yeast Applications and Post-Harvest Use of Controlled Atmosphere
The effects of pre-harvest applications of antagonistic yeast and controlled atmosphere storage treatments on inhibiting Botrytis cinerea decay and maintaining the quality of table grapes were compared to identify a treatment that could replace the use of sulphur dioxide (SO2) during post-harvest handling. Treatments for this study included pre-harvest application of antagonistic yeasts Cryptococcus albidus (Yieldplus®), Cryptococcus sp. (LF) and Candida pelliculosa (R951) on table grapes (cvs. ‘Barlinka’, ‘Dauphine’, ‘Red Globe’, ‘Sunred Seedless’ and ‘ThompsonSeedless’) from 2001 to 2003. Grapes were stored under regular (air), controlled atmosphere (CA, O2 + CO2) and SO2 conditions at -0.5°C and subsequent storage at a 15°C to simulate shelf-life conditions. Results of this study showed that Botrytis decay levels did not develop rapidly due to low temperatures (-0.5°C vs 15°C), shorter storage periods (4 vs 8 weeks or 0 vs 7 vs 14 days), and CA treatment effects. The CA gas mixtures maintained commercially important low levels (less than 1%) of B. cinerea decay during the cold storage period at -0.5°C. However, during shelf-life storage at 15°C these low levels of decay could only be maintained by some of the SO2 treatments. A necessary commercial requirement is to maintain low decay levels for longer at higher shelf-life temperatures, forwhich this study cannot conclusively recommend a CA and/or antagonistic yeast treatment as an alternative to SO2. However, pre-harvest applications of the yeast and CA limited the general quality deterioration of the grapes at -0.5°C and 15°C compared to SO2 treatments. Inclusion of macro- or micro-perforated polyethylene packaging liners in combination with CA and pre-harvest yeast treatments did not show obvious negative effects on quality parameters in this study. Discovery and selection of yeast strains that survive under low temperatures and CA conditions would make suitable candidates for continued control of decay development on the fruit surface during shelf-life storage periods
Efficacy of fungicides, plant resistance activators and biological control agents against guava wilt disease caused by Nalanthamala psidii
Guava wilt disease (GWD) caused by the fungus Nalanthamala psidii remains a major
constraint to guava production in South Africa and South East Asia. In the current study,
chemical and biological products as well as plant resistance activators were evaluated for
control of GWD in shadehouse and glasshouse trials. In all trials, one-year-old ‘TS-G2’
guava plants were used. Plants were inoculated with a macerated culture suspension of a
mixture of three isolates of N. psidii after artificial wounding of the roots. Products were
applied as a soil drench or as a full cover spray. In trial 1 plants were evaluated according
to a disease severity scale. In trial 2 and 3 data were recorded as number of dead plants at
the termination of the trial. None of the chemical treatments caused a significant
suppression of the disease. The best control was achieved with the combination of
rhizobacterial strains Bacillus cereus S7 and Paenibacillus alvei T29 resulting in 53.4%
and 50% disease control in trials 2 and 3 respectively. This treatment also seems to have a
plant growth enhancing effect apart from disease suppression. This is to our knowledge
the first report of control of GWD by means of bacterial antagonists.http://www.tandfonline.com/loi/tjps202017-11-30hb2017Microbiology and Plant Patholog
The unusual optical afterglow of the gamma-ray burst GRB 021004: Color changes and short-time-scale variability
We report UBVRI observations of the optical afterglow of the gamma-ray burst
GRB 021004. We observed significant (10-20%) deviations from a power law decay
on several time scales, ranging from a few hours down to 20-30 minutes. We also
observed a significant color change starting ~1.5 days after the burst,
confirming the spectroscopic results already reported by Matheson et al.
(2002). We discuss these results in the context of several models that have
recently been proposed to account for the anomalous photometric behavior of
this event.Comment: Submitted to ApJL, 14 pages, 4 figures. Data available on anonymous
ftp at ftp://cfa-ftp.harvard.edu/pub/kstanek/GRB02100
Probing the atmosphere of a solar-like star by galactic microlensing at high magnification
We report a measurement of limb darkening of a solar-like star in the very
high magnification microlensing event MOA 2002-BLG-33. A 15 hour deviation from
the light curve profile expected for a single lens was monitored intensively in
V and I passbands by five telescopes spanning the globe. Our modelling of the
light curve showed the lens to be a close binary system whose centre-of-mass
passed almost directly in front of the source star. The source star was
identified as an F8-G2 main sequence turn-off star. The measured stellar
profiles agree with current stellar atmosphere theory to within ~4% in two
passbands. The effective angular resolution of the measurements is <1
micro-arcsec. These are the first limb darkening measurements obtained by
microlensing for a Solar-like star.Comment: Accepted for publication in A&A Letters. 5 pages, 2 embedded colour
ps figures plus 1 jpg figure. Version with all figures embedded available
from: http://www.roe.ac.uk/~iab/moa33paper
Limits on additional planetary companions to OGLE-2005-BLG-390L
We investigate constraints on additional planets orbiting the distant M-dwarf
star OGLE-2005-BLG-390L, around which photometric microlensing data has
revealed the existence of the sub-Neptune-mass planet OGLE-2005-BLG-390Lb. We
specifically aim to study potential Jovian companions and compare our findings
with predictions from core-accretion and disc-instability models of planet
formation. We also obtain an estimate of the detection probability for
sub-Neptune mass planets similar to OGLE-2005-BLG-390Lb using a simplified
simulation of a microlensing experiment. We compute the efficiency of our
photometric data for detecting additional planets around OGLE-2005-BLG-390L, as
a function of the microlensing model parameters and convert it into a function
of the orbital axis and planet mass by means of an adopted model of the Milky
Way. We find that more than 50 % of potential planets with a mass in excess of
1 M_J between 1.1 and 2.3 AU around OGLE-2005-BLG-390L would have revealed
their existence, whereas for gas giants above 3 M_J in orbits between 1.5 and
2.2 AU, the detection efficiency reaches 70 %; however, no such companion was
observed. Our photometric microlensing data therefore do not contradict the
existence of gas giant planets at any separation orbiting OGLE-2005-BLG-390L.
Furthermore we find a detection probability for an OGLE-2005-BLG-390Lb-like
planet of around 2-5 %. In agreement with current planet formation theories,
this quantitatively supports the prediction that sub-Neptune mass planets are
common around low-mass stars.Comment: 10 pages, 4 figures, accepted by A&
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