62 research outputs found
Soil carbon estimation from eucalyptus grandis using canopy spectra
Mapping soil fertility parameters, such as soil carbon (C), is fundamentally important for forest management and research related to forest growth and climate change. This study seeks to establish the link between Eucalyptus grandis canopy spectra and soil carbon using raw and continuum-removed spectra. Canopy-level spectra were collected using a hand-held 350-2500nm spectroradiometer and soil samples obtained at depths from 0-1.2m and analysed for carbon content. Partial least squares (PLS) selection was used to selected optimal bands for soil carbon assessment and further bootstrapped to select 35 Variable Importance in Projection (VIP) parameters, based on correlation (r) and standard error (SE). Results indicated that continuum-removed spectra and soil C yielded stronger significant correlations, when compared to soil C and raw spectra. The predictive models developed for future soil C estimation showed that continuum-removed spectra exhibited improved adjusted R2 values in both instances, i.e., when using all significant bands and the most significant 35 VIP bands. The results indicate a distinct potential for forest managers to monitor the status of soil C in commercial forestry compartments using canopy-level spectra and determine how much fertilizer is required to optimize tree growth.Keywords: Soil carbon, Canopy spectr
Uterine smooth muscle tumours of uncertain malignant potential : a case report and literature review
A 41 year-old, gravida 2, para 2, was referred with abnormal uterine bleeding that got progressively worse over the past 6 months. Examination and ultrasound revealed a large fundal myoma of 8 x 8cm. Pap smear and endometrial biopsy was normal. Patient opted for a hysterectomy after appropriate counselling. Histopathology reported a smooth muscle tumours of uncertain malignant potential (STUMP).http://www.journals.co.za/content/journal/medoghj2020Obstetrics and Gynaecolog
Seasonal variation in cotyledoside concentration of Tylecodon wallichii (Harv.) Tolken subsp. wallichii sampled in a krimpsiekte-prevalent region
Krimpsiekte, an economically important neuromuscular affliction of small
stock, follows upon ingestion of certain members of the Crassulaceae
(plakkies) containing cumulative neurotoxic bufadienolides. Tylecodon
wallichii (Harv.) Tolken subsp. wallichii is probably the most
important species of the group of plants causing krimpsiekte. The
growing tip of the stem and various other plant parts of T. wallichii,
when available, were collected monthly. The seasonal variation in
cotyledoside content of the plant was measured. Cotyledoside
concentration was determined by high performance liquid
chromatographic-electrospray mass spectrometry analysis (HPLC-ESMS). The
cotyledoside concentration in the plant stems fluctuated substantially
during the year, but tended to be higher in the cold winter months and
increased again in the spring and early summer. Elevated plant stem
concentrations corresponded with natural field outbreaks of krimpsiekte,
which usually occur during the winter to early summer. The highest
cotyledoside concentrations were detected in the flowering stalk.
Cotyledoside was not the only component of this type in the plant, as
mass spectrometry revealed the presence of other, possibly related,
compounds.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201
Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR
New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and
NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a
quiescent state since at least early 2015, reactivated between 2017 March 19
and April 5. The radio flux density, while variable, is approximately 100x
larger than during its dormant state. The X-ray flux one month after
reactivation was at least 800x larger than during quiescence, and has been
decaying exponentially on a 111+/-19 day timescale. This high-flux state,
together with a radio-derived rotational ephemeris, enabled for the first time
the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV
pulsed fraction is comparable to the smallest observed for magnetars. The
overall pulsar geometry inferred from polarized radio emission appears to be
broadly consistent with that determined 6-8 years earlier. However, rotating
vector model fits suggest that we are now seeing radio emission from a
different location in the magnetosphere than previously. This indicates a novel
way in which radio emission from magnetars can differ from that of ordinary
pulsars. The torque on the neutron star is varying rapidly and unsteadily, as
is common for magnetars following outburst, having changed by a factor of 7
within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure
Paediatric HIV management at primary care level: an evaluation of the integrated management of childhood illness (IMCI) guidelines for HIV
The use of airborne laser scanning to develop a pixel-based stratification for a verified carbon offset project
Background
The voluntary carbon market is a new and growing market that is increasingly important to consider in managing forestland. Monitoring, reporting, and verifying carbon stocks and fluxes at a project level is the single largest direct cost of a forest carbon offset project. There are now many methods for estimating forest stocks with high accuracy that use both Airborne Laser Scanning (ALS) and high-resolution optical remote sensing data. However, many of these methods are not appropriate for use under existing carbon offset standards and most have not been field tested. Results
This paper presents a pixel-based forest stratification method that uses both ALS and optical remote sensing data to optimally partition the variability across an ~10,000 ha forest ownership in Mendocino County, CA, USA. This new stratification approach improved the accuracy of the forest inventory, reduced the cost of field-based inventory, and provides a powerful tool for future management planning. This approach also details a method of determining the optimum pixel size to best partition a forest. Conclusions
The use of ALS and optical remote sensing data can help reduce the cost of field inventory and can help to locate areas that need the most intensive inventory effort. This pixel-based stratification method may provide a cost-effective approach to reducing inventory costs over larger areas when the remote sensing data acquisition costs can be kept low on a per acre basis
A BOX-COUNTING METHOD TO CHARACTERIZE DEGREES OF FOLIAGE CLUMPING USING AIRBORNE AND SIMULATED LIDAR DATA
Monitoring forest productivity and health is key to sustainable ecosystem management and informed decision making. A key
parameter used in monitoring forest resources is the leaf area index (LAI), which is defined as the one-sided leaf area per unit ground
area and is used to describe the canopy radiation regime, among other forest biophysical dynamics. Traditional optics-based methods
to estimate LAI rely on the measurement of canopy transmission and foliage clumping. Extending optical methods to LiDAR data
has been challenging and studies have reported effective LAI assessments, with no further quantification of foliage clumping. This
study investigates the use of the box-counting method to assess the fractal dimension of point cloud data for contrasting forest types
and along a gradient of foliage dispersal. We demonstrate the box-counting method on simulated ‘range-to-hit’, as well as acquired
airborne discrete LiDAR data. Coherent results obtained from the different test cases hint at the potential of the box-counting fractal
dimension to characterize foliage clumping and bode well for the use of clumping assessments in support of airborne, wall-to-wall
estimates of LAI
Human-modified landscapes: patterns of fine-scale woody vegetation structure in communal savannah rangelands
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