A STIS Survey for OVI Absorption Systems at 0.12 < z < 0.5 I.: The Statistical Properties of Ionized Gas

We have conducted a systematic survey for intervening OVI absorbers in available echelle spectra of 16 QSOs at z_QSO = 0.17-0.57. These spectra were obtained using HST/STIS with the E140M grating. Our search uncovered a total of 27 foreground OVI absorbers with rest-frame absorption equivalent width W_r(1031) > 25mA. Ten of these QSOs exhibit strong OVI absorbers in their vicinity. Our OVI survey does not require the known presence of Lya, and the echelle resolution allows us to identify the OVI absorption doublet based on their common line centroid and known flux ratio. We estimate the total redshift survey path, \Delta z, using a series of Monte-Carlo simulations, and find that \Delta z=1.66, 2.18, and 2.42 for absorbers of strength W_r = 30, 50 and 80mA, respectively, leading to a number density of dN(W > 50mA)/dz = 6.7 +/- 1.7 and dN(W > 30mA)/dz = 10.4 +/- 2.2. In contrast, we also measure dN/dz = 27 +/- 9 for OVI absorbers of W_r > 50mA at |\Delta v|< 5000 kms from the background QSOs. Using the random sample of OVI absorbers with well characterized survey completeness, we estimate a mean cosmological mass density of the OVI gas \Omega(OVI)h = 1.7 +/- 0.3 x 10^-7. In addition, we show that <5% of OVI absorbers originate in underdense regions that do not show a significant trace of HI. Furthermore, we show that the neutral gas column N(HI) associated with these OVI absorbers spans nearly five orders of magnitude, and show moderate correlation with N(OVI). Finally, while the number density of OVI absorbers varies substantially from one sightline to another, it also appears to be inversely correlated with the number density of HI absorbers along individual lines of sight.Comment: 12 pages. ApJ accepte

Glial regenerative cell types in the superficial cortex in cortical dysplasia subtypes

Purpose: Focal Cortical Dysplasias (FCD) are localized malformative brain lesions in epilepsy. FCD3a associated with hippocampal sclerosis, affects the superficial cortex and is presumed to have an ‘acquired’ rather than developmental origin. Precursor cells may arise outside neurogenic zones including cortical layer I. Our aim was to characterise subsets of glial progenitor cells in the superficial cortical layers, known to be involved in gliosis and gliogenesis and that could distinguish FCD3a from other subtypes. Methods: Using immunohistochemistry we quantified the density of glial progenitor subsets in superficial cortex layers using markers against PAX6, GFAP, Olig2 and PDGFRβ and proliferation marker MCM2 in ten FCD3a cases compared to 18 other FCD types and 11 non-FCD controls. Key Findings: Glial progenitor cells types were present in the cortical layer I and II in all FCD groups. GFAP cells frequently expressed PAX6 and significantly higher GFAP/PAX6 than GFAP/MCM2 cell densities were identified in the FCD3a group (p<0.05). Olig2 cell densities were significantly higher in FCD3b than FCD3a (p=0.002) and significantly higher GFAP/MCM2 compared to PDGFRβ/MCM2 cell densities were identified in both FCD3b and FCD2 groups. There was no correlation between cell densities and the age of patients at surgery and between cortical regions. Significance: Immature and proliferative glial populations across FCD variants reflect ‘reactive cell types and differences may provide insight into underlying pathomechanisms. Higher PAX6 expression in astroglial cells in FCD3a may indicate a switch to astrocytic maturation and enhanced superficial gliosis. Higher Olig2 and GFAP/MCM2 densities in FCD3b may reflect margins of the tumour infiltration zone rather than true cortical dysplasia

Spatiotemporal dynamics of PDGFRβ expression in pericytes and glial scar formation in penetrating brain injuries in adults

Aims: Understanding the spatiotemporal dynamics of reactive cell types following brain injury is important for future therapeutic interventions. We have previously used penetrating cortical injuries following intracranial recordings as a brain repair model to study scar-forming nestin-expressing cells. We now explore the relationship between nestin-expressing cells, PDGFRβ+ pericytes and Olig2+ glia, including their proliferation and functional maturation. Methods: In 32 cases, ranging from 3 to 461 days post injury (dpi), immunohistochemistry for PDGFRβ, nestin, GFAP, Olig2, MCM2, Aquaporin 4 (Aq4), Glutamine Synthetase (GS), and Connexin 43 (Cx43) were quantified for cell densities, labelling index (LI) and cellular co-expression at the injury site compared to control regions. Results: PDGFRβ labelling highlighted both pericytes and multipolar parenchymal cells. PDGFRβ LI and PDGFRβ+/MCM2+ cells significantly increased in injury zones at 10-13 dpi with migration of pericytes away from vessels with increased co-localisation of PDGRFβ with nestin compared to control regions (p < 0.005). Olig2+/MCM2+ cell populations peaked at 13 dpi with significantly higher cell densities at injury sites than in control regions (p < 0.01) and decreasing with dpi (p < 0.05). Cx43 LI was reduced in acute injuries but increased with dpi (p < 0.05) showing significant cellular co-localisation with nestin and GFAP (p<0.005 and p<0.0001) but not PDGFRβ. Conclusions: These findings indicate that PDGFRβ+ and Olig2+ cells contribute to the proliferative fraction following penetrating brain injuries, with evidence of pericyte migration. Dynamic changes in Cx43 in glial cell types with dpi suggests functional alterations during temporal stages of brain repair

The effect of intravenous amino acids on plasma amino acid concentration during total parenteral nutrition in infants with necrotizing enterocolitis

CITATION: Thom, J. C., Victor, T. & Pichanick, A. M. E. 1981. The effect of intravenous amino acids on plasma amino acid concentration during total parenteral nutrition in infants with necrotizing enterocolitis. South African Medical Journal, 59:946-948.The original publication is available at http://www.samj.org.zaPlasma aminograms of infants receiving total parenteral nutrition as part of the treatment for necrotizing enterocolitis were studied. Their ages varied from 2 to 60 days and their mean birth mass was 1621 g (range 760-2550 g). The intravenous administration of amino acids produced changes in plasma amino acid levels corresponding to the concentration of individual amino acid levels in the solution employed: higher levels of amino acids in the infusate produced increased plasma levels, whereas low plasma levels were obtained for amino acids not present or present in small amounts according to the solution used. The infants did not appear to suffer in any way, but the long-term effects still have to be evaluated. Pending further knowledge in this regard it is suggested that plasma amino acid levels should be maintained as near to normal values as possible. This could probably be achieved by the use of amino acid solutions specially formulated according to the amino acid profile of breast milk or the plasma amino acid profile of normal infants.Publisher’s versio

Process evaluation of an innovative sun protection intervention targeting adolescents

The purpose of the current intervention was to target a defined segment of the adolescent population with a sun protection ‘offering’ that positioned sun protection as beneficial and addressed identified barriers (particularly inconvenience and image). A community intervention was conducted in one defined geographic region over the 2009/2010 Summer school holidays. Key elements of the intervention included the distribution of augmented products, promotional materials with a pre-tested impactful message, and partnerships with community and commercial organisations. The intervention was successful in creating interest and attention among adolescents. This paper reports on the process evaluations, focusing on barriers, facilitators and lessons learned

Application of palaeoecology for peatland conservation at Mossdale Moor, UK

In a recent discussion of research priorities for palaeoecology, it was suggested that palaeoecological data can be applied and used to inform nature conservation practice. The present study exemplifies this approach and was conducted on a degraded blanket mire in Yorkshire, UK, in collaboration with a field-based moorland restoration agency. High-resolution, multiproxy palaeoecological analyses on a peat core from Mossdale Moor reconstructed mid to late-Holocene vegetation changes. Humification, pollen, plant macrofossil and charcoal analyses carried out throughout the peat profile show marked changes in species composition and indicate their potential causes. Results suggest that human clearance in the Mesolithic–Neolithic transition may have initiated peat growth at Mossdale Moor, making this landscape ‘semi-natural’ in its origin. Further human-induced changes are identified at 1300 cal years BP, most likely clearance by fire, and between 20 and 0 cm depth where a substantial charcoal increase is interpreted as recent (<400 years) management practices using burning to encourage browse on the moor. The long-term ecological history of the moor, derived using palaeoecological techniques, will be used to inform conservation practice and to help set feasible targets for restoration and conservation at Mossdale Moo

Spatiotemporal dynamics of PDGFRβ expression in pericytes and glial scar formation in penetrating brain injuries in adults

AIMS: Understanding the spatiotemporal dynamics of reactive cell types following brain injury is important for future therapeutic interventions. We have previously used penetrating cortical injuries following intracranial recordings as a brain repair model to study scar-forming nestin-expressing cells. We now explore the relationship between nestin-expressing cells, PDGFRβ+ pericytes and Olig2+ glia, including their proliferation and functional maturation. METHODS: In 32 cases, ranging from 3 to 461 days post injury (dpi), immunohistochemistry for PDGFRβ, nestin, GFAP, Olig2, MCM2, Aquaporin 4 (Aq4), Glutamine Synthetase (GS), and Connexin 43 (Cx43) were quantified for cell densities, labelling index (LI) and cellular co-expression at the injury site compared to control regions. RESULTS: PDGFRβ labelling highlighted both pericytes and multipolar parenchymal cells. PDGFRβ LI and PDGFRβ+ /MCM2+ cells significantly increased in injury zones at 10-13 dpi with migration of pericytes away from vessels with increased co-localisation of PDGRFβ with nestin compared to control regions (p < 0.005). Olig2+ /MCM2+ cell populations peaked at 13 dpi with significantly higher cell densities at injury sites than in control regions (p < 0.01) and decreasing with dpi (p < 0.05). Cx43 LI was reduced in acute injuries but increased with dpi (p < 0.05) showing significant cellular co-localisation with nestin and GFAP (p<0.005 and p<0.0001) but not PDGFRβ. CONCLUSIONS: These findings indicate that PDGFRβ+ and Olig2+ cells contribute to the proliferative fraction following penetrating brain injuries, with evidence of pericyte migration. Dynamic changes in Cx43 in glial cell types with dpi suggests functional alterations during temporal stages of brain repair. This article is protected by copyright. All rights reserved

Glial regenerative cell types in the superficial cortex in cortical dysplasia subtypes

PURPOSE: Focal Cortical Dysplasias (FCD) are localized malformative brain lesions in epilepsy. FCD3a associated with hippocampal sclerosis, affects the superficial cortex and is presumed to have an 'acquired' rather than developmental origin. Precursor cells may arise outside neurogenic zones including cortical layer I. Our aim was to characterise subsets of glial progenitor cells in the superficial cortical layers, known to be involved in gliosis and gliogenesis and that could distinguish FCD3a from other subtypes. METHODS: Using immunohistochemistry we quantified the density of glial progenitor subsets in superficial cortex layers using markers against PAX6, GFAP, Olig2 and PDGFRβ and proliferation marker MCM2 in ten FCD3a cases compared to 18 other FCD types and 11 non-FCD controls. KEY FINDINGS: Glial progenitor cells types were present in the cortical layer I and II in all FCD groups. GFAP cells frequently expressed PAX6 and significantly higher GFAP/PAX6 than GFAP/MCM2 cell densities were identified in the FCD3a group (p < 0.05). Olig2 cell densities were significantly higher in FCD3b than FCD3a (p = 0.002) and significantly higher GFAP/MCM2 compared to PDGFRβ/MCM2 cell densities were identified in both FCD3b and FCD2 groups. There was no correlation between cell densities and the age of patients at surgery and between cortical regions. SIGNIFICANCE: Immature and proliferative glial populations across FCD variants reflect reactive cell types and differences may provide insight into underlying pathomechanisms. Higher PAX6 expression in astroglial cells in FCD3a may indicate a switch to astrocytic maturation and enhanced superficial gliosis. Higher Olig2 and GFAP/MCM2 densities in FCD3b may reflect margins of the tumour infiltration zone rather than true cortical dysplasia

A Historical Perspective for Incorporating the Airframe and Powerplant Certificate as a Relevant Engineering Technology Skill

At first, the concept of an engineering technology program containing an Airframe and Powerplant certificate (A&P) program might seem to be odd. At many colleges and universities the A&P program is considered to be a vocational certificate program, while the engineering program is considered to be more of a professional degree program. The engineering faculty credentials and mandated classroom requirements for engineering have traditionally been diametrically opposed with the A&P certification. But on second look the combination of these two disciplines may not be as odd as it first seems. In fact, the A&P curriculums in four-year colleges today are not that different from where the profession of engineering was in 1900. By understanding the roots of engineering education, and the changes in engineering education over the last century, it becomes easy to see how the A&P certificate holds relevance in engineering education