221 research outputs found
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<i>Aloe succotrina</i> (Asphodelaceae)
Aloe succotrina has a very long and complex taxonomic and nomenclatural history with wrong synonymy that is rivalled by few other aloes. This is mostly due to early authors wrongly assuming that this plant is from the Island of Socotra (Reynolds 1950). It has been in cultivation in Europe for over three hundred years, so consequently it is rather surprising that this iconic fynbos species has not featured in this journal until now
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Materials for phantoms for terahertz pulsed imaging
Phantoms are commonly used in medical imaging for quality assurance, calibration, research and teaching. They may include test patterns or simulations of organs, but in either case a tissue substitute medium is an important component of the phantom. The aim of this work was to identify materials suitable for use as tissue substitutes for the relatively new medical imaging modality terahertz pulsed imaging. Samples of different concentrations of the candidate materials TX151 and napthol green dye were prepared, and measurements made of the frequency-dependent absorption coefficient (0.5 to 1.5 THz) and refractive index (0.5 to 1.0 THz). These results were compared qualitatively with measurements made in a similar way on samples of excised human tissue (skin, adipose tissue and striated muscle). Both materials would be suitable for phantoms where the dominant mechanism to be simulated is absorption (similar to ∼100 cm(-1) at 1 THz) and where simulation of the strength of reflections from boundaries is not important; for example, test patterns for spatial resolution measurements. Only TX151 had a frequency-dependent refractive index close to that of tissue, and could therefore be used to simulate the layered structure of skin, the complexity of microvasculature or to investigate frequency-dependent interference effects that have been noted in terahertz images
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<i>Kalanchoe beharensis</i>. Crassulaceae: Kalanchooideae
Kalanchoe beharensis is one of the largest species of the diverse genus, reaching a height of about 3 m, one of only a few that can be regarded as truly arborescent. The species is discussed in detail in terms of its history, taxonomy, relationships, distribution, habitat, variability and cultivation. It is described in full and illustrated with a water-colour painting and colour photos. This species is endemic to and fairly widespread in western, central and eastern Madagascar including Behara after which it is named. It has been introduced to several mild-climate parts of the world and is now widespread in cultivation
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Terahertz deconvolution
The ability to retrieve information from different layers within a stratified sample using terahertz pulsed reflection imaging and spectroscopy has traditionally been resolution limited by the pulse width available. In this paper, a deconvolution algorithm is presented which circumvents this resolution limit, enabling deep sub-wavelength and sub-pulse width depth resolution. The algorithm is explained through theoretical investigation, and demonstrated by reconstructing signals reflected from boundaries in stratified materials that cannot be resolved directly from the unprocessed time-domain reflection signal. Furthermore, the deconvolution technique has been used to recreate sub-surface images from a stratified sample: imaging the reverse side of a piece of paper
Terahertz frequency-wavelet domain deconvolution for stratigraphic and subsurface investigation of art painting
Terahertz frequency-wavelet deconvolution is utilized specifically for the stratigraphic and subsurface investigation of art paintings with terahertz reflective imaging. In order to resolve the optically thin paint layers, a deconvolution technique is enhanced by the combination of frequency-domain filtering and stationary wavelet shrinkage, and applied to investigate a mid-20th century Italian oil painting on paperboard, After Fishing, by Ausonio Tanda. Based on the deconvolved terahertz data, the stratigraphy of the painting including the paint layers is reconstructed and subsurface features are clearly revealed, demonstrating that terahertz frequencywavelet deconvolution can be an effective tool to characterize stratified systems with optically thin layers
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Aloiampelos ciliaris var. ciliaris. Asphodelaceae: Alooideae
Aloiampelos ciliaris is the type of a new genus of just seven species separated from Aloe in 2013 to accommodate the scrambling South African aloes. The history, taxonomy, distribution, ecology, cytology and cultivation of this species are all discussed in detail. This species is unique for Southern Africa in having a hexaploid chromosome count of 2n=42. The leaf structure is also distinctive with an amplexicaul base bearing conspicuous white cilia. It is endemic to the Eastern Cape Province
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Cyclododecane as a contrast improving substance for the terahertz imaging of artworks
This paper presents measurements of the terahertz properties of the art conservation substance cyclododecane, demonstrating that it can act as a contrast improving agent in the terahertz imaging of concealed wall paintings. Results are presented which show that the terahertz optical properties of cyclododecane are dependent on the rate at which it has cooled from the melt. Based on the results, a theoretical explanation of the contrast enhancement mechanism is postulated. The findings presented here may lead to the development of novel coating materials that could improve the quality of terahertz images in a variety of fields and not just in art conservation
Combined chelation therapy in thalassemia major for the treatment of severe myocardial siderosis with left ventricular dysfunction
<p>Abstract</p> <p>Background</p> <p>In thalassemia major (TM), severe cardiac siderosis can be treated by continuous parenteral deferoxamine, but poor compliance, complications and deaths occur. Combined chelation therapy with deferiprone and deferoxamine is effective for moderate myocardial siderosis, but has not been prospectively examined in severe myocardial siderosis.</p> <p>Methods</p> <p>T2* cardiovascular magnetic resonance (CMR) was performed in 167 TM patients receiving standard subcutaneous deferoxamine monotherapy, and 22 had severe myocardial siderosis (T2* < 8 ms) with impaired left ventricular (LV) function. Fifteen of these patients received combination therapy with subcutaneous deferoxamine and oral deferiprone with CMR follow-up.</p> <p>Results</p> <p>At baseline, deferoxamine was prescribed at 38 ± 10.2 mg/kg for 5.3 days/week, and deferiprone at 73.9 ± 4.0 mg/kg/day. All patients continued both deferiprone and deferoxamine for 12 months. There were no deaths or new cardiovascular complications. The myocardial T2* improved (5.7 ± 0.98 ms to 7.9 ± 2.47 ms; p = 0.010), with concomitant improvement in LV ejection fraction (51.2 ± 10.9% to 65.6 ± 6.7%; p < 0.001). Serum ferritin improved from 2057 (CV 7.6%) to 666 (CV 13.2%) μg/L (p < 0.001), and liver iron improved (liver T2*: 3.7 ± 2.9 ms to 10.8 ± 7.3 ms; p = 0.006).</p> <p>Conclusion</p> <p>In patients with severe myocardial siderosis and impaired LV function, combined chelation therapy with subcutaneous deferoxamine and oral deferiprone reduces myocardial iron and improves cardiac function. This treatment is considerably less onerous for the patient than conventional high dose continuous subcutaneous or intravenous deferoxamine monotherapy, and may be considered as an alternative. Very prolonged tailored treatment with iron chelation is necessary to clear myocardial iron, and alterations in chelation must be guided by repeated myocardial T2* scans.</p> <p>Trial registration</p> <p>This trial is registered as NCT00103753</p
Right ventricular volumes and function in thalassemia major patients in the absence of myocardial iron overload
<p>Abstract</p> <p>Aim</p> <p>We aimed to define reference ranges for right ventricular (RV) volumes, ejection fraction (EF) in thalassemia major patients (TM) without myocardial iron overload.</p> <p>Methods and results</p> <p>RV volumes, EF and mass were measured in 80 TM patients who had no myocardial iron overload (myocardial T2* > 20 ms by cardiovascular magnetic resonance). All patients were receiving deferoxamine chelation and none had evidence of pulmonary hypertension or other cardiovascular comorbidity. Forty age and sex matched healthy non-anemic volunteers acted as controls. The mean RV EF was higher in TM patients than controls (males 66.2 ± 4.1% vs 61.6 ± 6%, p = 0.0009; females 66.3 ± 5.1% vs 62.6 ± 6.4%, p = 0.017), which yielded a raised lower threshold of normality for RV EF in TM patients (males 58.0% vs 50.0% and females 56.4% vs 50.1%). RV end-diastolic volume index was higher in male TM patients (mean 98.1 ± 17.3 mL vs 88.4 ± 11.2 mL/m2, p = 0.027), with a higher upper limit (132 vs 110 mL/m2) but this difference was of borderline significance for females (mean 86.5 ± 13.6 mL vs 80.3 ± 12.8 mL/m2, p = 0.09, with upper limit of 113 vs 105 mL/m2). The cardiac index was raised in TM patients (males 4.8 ± 1.0 L/min vs 3.4 ± 0.7 L/min, p < 0.0001; females 4.5 ± 0.8 L/min vs 3.2 ± 0.8 L/min, p < 0.0001). No differences in RV mass index were identified.</p> <p>Conclusion</p> <p>The normal ranges for functional RV parameters in TM patients with no evidence of myocardial iron overload differ from healthy non-anemic controls. The new reference RV ranges are important for determining the functional effects of myocardial iron overload in TM patients.</p
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