51 research outputs found
A Tight-Binding Investigation of the NaxCoO2 Fermi Surface
We perform an orthogonal basis tight binding fit to an LAPW calculation of
paramagnetic NaCoO for several dopings. The optimal position of the
apical oxygen at each doping is resolved, revealing a non-trivial dependence of
the band structure and Fermi surface on oxygen height. We find that the small
e hole pockets are preserved throughout all investigated dopings and
discuss some possible reasons for the lack of experimental evidence for these
Fermi sheets
Die-back of kiaat (Pterocarpus angolensis) in southern Africa : a cause for concern?
Pterocarpus angolensis (kiaat) is a well-known southern African tree species of commercial importance that occurs in several
vegetation types in the Zambezian regional centre of endemism. The most prominent of these vegetation types are the
Zambezian miombo woodland and undifferentiated woodland. A diverse range of ecosystems within these vegetation types
necessitate adaptation by tree species to survive extremes of drought, temperature, altitude, soil nutrition and tolerate fire
in order to compete with other plant species. There are several reports of a die-back disease of P. angolensis in Zambia,
Zimbabwe and South Africa, but very little is known regarding the cause or significance of this problem. In this review, we
provide details regarding the history of the disease and consider its possible causal agents. A pathology study conducted
at three locations in South Africa on diseased and dying trees resulted in the collection of 199 fungal isolates; comprising
saprophytic species such as Candida, Penicillium and Humicola, and potentially pathogenic species such as Lasiodiplodia
theobromae, Cytospora spp. and Fusarium spp. Drought, during several years preceding disease, along with a lack of fire
management may have contributed to both the present and past reports of tree die-back and death. Finally, an analysis is
made of the importance of the problem and actions that might be taken to alleviate it.DST/NRF Centre of Excellence in Tree Health Biotechnology (CTHB)http://www.tandfonline.com/loi/tsfs20nf201
Confronting the constraints of morphological taxonomy in the Botryosphaeriales
Identification of fungi and the International Code of Nomenclature underpinning this process, rests
strongly on the characterisation of morphological structures. Yet, the value of these characters to define species in
many groups has become questionable or even superfluous. This has emerged as DNA-based techniques have
increasingly revealed cryptic species and species complexes. This problem is vividly illustrated in the present
study where 105 isolates of the Botryosphaeriales were recovered from both healthy and diseased woody tissues
of native Acacia spp. in Namibia and South Africa. Thirteen phylogenetically distinct groups were identified based
on Internal Transcribed Spacer (ITS) rDNA PCR-RFLP and translation elongation factor 1-α (TEF1-α) sequence
data, two loci that are known to be reliable markers to distinguish species in the Botryosphaeriales. Four of these
groups could be linked reliably to sequence data for formerly described species, including Botryosphaeria dothidea,
Dothiorella dulcispinae, Lasiodiplodia pseudotheobromae and Spencermartinsia viticola. Nine groups, however,
could not be linked to any other species known from culture and for which sequence data are available. These
groups are, therefore, described as Aplosporella africana, A. papillata, Botryosphaeria auasmontanum, Dothiorella
capri-amissi, Do. oblonga, Lasiodiplodia pyriformis, Spencermartinsia rosulata, Sphaeropsis variabilis and an undescribed
Neofusicoccum sp. The species described here could not be reliably compared with the thousands of
taxa described in these genera from other hosts and regions, where only morphological data are available. Such
comparison would be possible only if all previously described taxa are epitypified, which is not a viable objective
for the two families, Botryosphaeriaceae and Aplosporellaceae, in the Botryosphaeriales identified here. The extent
of diversity of the Botryosphaeriales revealed in this and other recent studies is expected to reflect that of other
undersampled regions and hosts, and illustrates the urgency to find more effective ways to describe species in
this, and indeed other, groups of fungi.THRIP initiative of the Department of Trade and Industry, DST/NRF Centre of
Excellence in Tree Health Biotechnology (CTHB), (DST) and National Research Foundation (NRF).http://www.persoonia.orghttp://www.ingentaconnect.com/content/nhn/pimjtm201
Randomized controlled phase 2 trial of hydroxychloroquine in childhood interstitial lung disease
Background
No results of controlled trials are available for any of the few treatments offered to children with interstitial lung diseases (chILD). We evaluated hydroxychloroquine (HCQ) in a phase 2, prospective, multicentre, 1:1-randomized, double-blind, placebo-controlled, parallel-group/crossover trial. HCQ (START arm) or placebo were given for 4 weeks. Then all subjects received HCQ for another 4 weeks. In the STOP arm subjects already taking HCQ were randomized to 12 weeks of HCQ or placebo (= withdrawal of HCQ). Then all subjects stopped treatment and were observed for another 12 weeks.
Results
26 subjects were included in the START arm, 9 in the STOP arm, of these four subjects participated in both arms. The primary endpoint, presence or absence of a response to treatment, assessed as oxygenation (calculated from a change in transcutaneous O 2 -saturation of ≥ 5%, respiratory rate ≥ 20% or level of respiratory support), did not differ between placebo and HCQ groups. Secondary endpoints including change of O 2 -saturation ≥ 3%, health related quality of life, pulmonary function and 6-min-walk-test distance, were not different between groups. Finally combining all placebo and all HCQ treatment periods did not identify significant treatment effects. Overall effect sizes were small. HCQ was well tolerated, adverse events were not different between placebo and HCQ.
Conclusions
Acknowledging important shortcomings of the study, including a small study population, the treatment duration, lack of outcomes like lung function testing below age of 6 years, the small effect size of HCQ treatment observed requires careful reassessments of prescriptions in everyday practice (EudraCT-Nr.: 2013-003714-40, www.clinicaltrialsregister.eu , registered 02.07.2013)
- …