3,256 research outputs found
Craniometaphyseal and craniodiaphyseal dysplasia, head and neck manifestations and management
Craniometaphyseal and craniodiaphyseal dysplasia are rare genetic disorders of bone due to modelling errors of long bones and skull bones. These syndromes present with multiple ENT symptomatology from an early age. The diagnostic distinction can now be made radiologically by serial skeletal survey which is important for prognosis. We review the clinical, radiological, computed tomography (CT) scan, otological, audiological and histopathological findings in two cases with craniodiaphyseal, and two cases with craniometaphyseal dysplasia, and report our experiences of medical and surgical treatment to date. In the craniodiaphyseal dysplasia, the hearing abnormality progressed from an initial conductive to a mixed loss on serial audiometric follow up. Temporal bone CT scans showed narrowing of the middle ear cavity, internal auditory meatus, and facial nerve canal at the geniculate ganglion. Benefits from choanal stenosis surgery, craniofacial remodelling and dacrocystorhinostomy were shortlived. Calcitriol therapy with a low calcium diet did not alter the clinical course of progression in our cases. The underlying defect, causing net bone formation in these phenotypically similar syndromes, appears to be different when based on the differing biochemical responses to calcitriol and bone biopsy findings. Increased numbers of osteoblasts were found in bone biopsies from both cases with craniodiaphyseal dysplasia. Early recognition is crucial in these conditions as therapy directed at the underlying bony defect has the best chance of success if initiated in infancy (Cole et al., 1988; Fanconi et al., 1988; Key et al., 1988)
Establishment of an Ensiling System for the Production of Lactic Acid from Sorghum bicolor (Sweet Sorghum) Biomass
Lactic acid is an economically important organic acid that has a wide range of applications in industry, including in the manufacture of sustainable and biodegradable plastic alternative poly-lactic acid (PLA). Transition towards a bio-based economy requires increased production of lactic acid and other industrially important chemicals from biomass. Lignocellulosic biomass is a preferred feedstock for production, as it is inexpensive and abundant, however the recalcitrant nature of lignocellulose makes its utilisation challenging. Therefore, development of a consolidated bioprocessing (CBP) system for efficient conversion of lignocellulosic biomass to value-added products is required. Lactic acid is currently produced via fermentation of expensive carbohydrate-based feedstocks by lactic acid bacteria (LAB). Application of an ensiling system may overcome problems associated with current fermentation methods and enable conversion of lignocellulosic biomass to lactic acid via CBP. Ensiling is commonly used for the preservation of freshly harvested crops for animal feed, including sweet sorghum, which contains a high concentration of soluble sugar and lignocellulose. In this study, a series of lab-scale ensiling experiments were performed, in which the effects of various conditions and additives on ensiling product yields from sweet sorghum were evaluated. Addition of CaCO3 was identified as an effective method of pH control, resulting in a 2.8 x increase in lactic acid production by endogenous LAB. Inoculation with two different species of LAB (Lactobacillus plantarum and Pediococcus acidilactici) and addition of a commercial cellulose enzyme package were demonstrated to have minimal influence on lactic acid yield compared to ensiling temperature and time. An ensiling temperature of 45 °C resulted in high lactic acid selectivity and potential degradation of some lignocellulose. However, due to variability between ensiling experiments, further investigation is required before optimal ensiling temperature and time can be confirmed for maximum production of lactic acid from sweet sorghum
Swartkrans as a case study in African cave taphonomy
Main articleBy taphonomy is meant the systematic study of death assemblages of once-living things in
this case of vertebrate animals. Such study may have various aims but in the present instance
my objective has been the interpretation of bone assemblages in the Swartkrans cave
to throw light on such topics as: 1. the ways in which bones found their way to the cave;
2. the nature of the animal communities which contributed bones to the assemblages and the
kind of environment in which the communities lived;
3. the behaviour of the hominids and other animals whose bones form part of the fossil
assemblage.
Swartkrans, though not a particularly large cave, is one of considerable complexity and can
be used as a case study to illuminate several principles in African cave taphonomy. Three of
these principles are discussed.Non
The contribution of Alun R. Hughes to the early development of cave taphonomy: a tribute
Tribute to Alun R. Hughe
Presidential address: taphonomy as an aid to African palaeontology
Presidential address for PSSA conferencePalaeontology has its roots in both the earth and life sciences. Its usefulness to geology
comes from the light which the understanding of fossils may throw on the stratigraphic relationships
of sediments, or the presence of economic deposits such as coal or oil. In biology,
the study of fossils has the same objectives as does the study of living animals or plants and
such objectives are generally reached in a series of steps which may be set out as follows.Non
The importance of Nama Group sediments and fossils to the debate about animal origins
Main articleThe purpose of this review is to draw attention to the contribution that Nama sediments and fossils
have made, and potentially can make, to the ongoing debate about metazoan origins. Two important
features of this debate concern the nature and systematic position of the late Proterozoic "Ediacaran"
fauna as well as the reasons for the sudden appearance in the fossil record of representatives of almost
all known animal phyla, during the Early-Middle Cambrian radiation. An additional vexing question
is the reason for the apparent absence of preserved representatives of ancestral metazoan lineages in
Proterozoic sediments, despite the fact that molecular evidence shows that such lineages had a long
his tory, prior to Cambrian times. Nama fossils and their enclosing sediments have made crucial
contributions to this debate and will surely continue to do so in the future.The Foundation for
Research Development in Pretoria
Dynamical Symmetry Breaking by SU(2) Gauge Bosons
This work explores the possibility of obtaining a mass gap in Yang-Mills
theories via the intrinsic gauge bosons, without invoking a separate Higgs
boson or fermion-antifermion pairs. Instead, pairs of gauge bosons in the spin
and isospin singlet state form a pair of composite Higgs bosons which can be
viewed as the simplest possible glueball of Yang-Mills gauge theories.
Quadratic and quartic gauge boson self-interactions form a potential that leads
to a finite expectation value of the gauge boson amplitude. Transverse
polarization ensures Lorentz invariance of the vacuum after averaging over all
possible polarization vectors. But the scalar pair products exhibit a finite
vacuum expectation value which breaks the gauge symmetry dynamically.
Compatibility with the standard Higgs potential determines the quadratic and
quartic coupling constants.Comment: 17 pages, 2 figures. Versions 2,3: added Ref. [15], augmented
Appendix B, clarified the text. Versions 4,5: added Eq. (35) + text (formula
for g), generalized Eq. (B17) + tex
A study of the effects of micro-gravity on seed germination
This study will identify characteristics of seed germination dependent upon gravity. To accomplish this objective, four different seed types will be germinated in space and then be compared to a control group germinated on Earth. Both the experimental and control groups will be analyzed on the cellular level for the size of cells, structural anomalies, and gravitational effects. The experiment will be conducted in a Get Away Special Canister (GAS Can no. 608) owned by the U.S. Space and Rocket Center and designed for students. The GAS Can will remain in the cargo bay of the Space Shuttle with minimal astronaut interaction
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