scholarly journals Palaeoclimates: the first two billion years

2006 ◽  
Vol 361 (1470) ◽  
pp. 917-929 ◽  
Author(s):  
James F Kasting ◽  
Shuhei Ono
Keyword(s):  
South Africa ◽  
Oxygen Isotopes ◽  
Natural Explanation ◽  
Witwatersrand Basin ◽  
Late Archaean ◽  
Bacterial Sulphate Reduction ◽  
Climatic Constraints ◽  
The Mean ◽  
High Concentrations ◽  
Earth’S Climate

Earth's climate during the Archaean remains highly uncertain, as the relevant geologic evidence is sparse and occasionally contradictory. Oxygen isotopes in cherts suggest that between 3.5 and 3.2 Gyr ago (Ga) the Archaean climate was hot (55–85 °C); however, the fact that these cherts have experienced only a modest amount of weathering suggests that the climate was temperate, as today. The presence of diamictites in the Pongola Supergroup and the Witwatersrand Basin of South Africa suggests that by 2.9 Ga the climate was glacial. The Late Archaean was relatively warm; then glaciation (possibly of global extent) reappeared in the Early Palaeoproterozoic, around 2.3–2.4 Ga. Fitting these climatic constraints with a model requires high concentrations of atmospheric CO 2 or CH 4 , or both. Solar luminosity was 20–25% lower than today, so elevated greenhouse gas concentrations were needed just to keep the mean surface temperature above freezing. A rise in O 2 at approximately 2.4 Ga, and a concomitant decrease in CH 4 , provides a natural explanation for the Palaeoproterozoic glaciations. The Mid-Archaean glaciations may have been caused by a drawdown in H 2 and CH 4 caused by the origin of bacterial sulphate reduction. More work is needed to test this latter hypothesis.

Studies of the oestrous cycle, oestrus and pregnancy in the koala (Phascolarctos cinereus)

Reproduction ◽  
2000 ◽  
pp. 49-57 ◽  
Author(s):  
SD Johnston ◽  
MR McGowan ◽  
P O'Callaghan ◽  
R Cox ◽  
V Nicolson
Keyword(s):  
Luteal Phase ◽  
Post Partum ◽  
Plasma Concentrations ◽  
External Genitalia ◽  
Oestrous Cycle ◽  
Phascolarctos Cinereus ◽  
Pregnant Females ◽  
Peripheral Plasma ◽  
The Mean ◽  
High Concentrations

As an integral part of the development of an artificial insemination programme in the captive koala, female reproductive physiology and behaviour were studied. The oestrous cycle in non-mated and mated koalas was characterized by means of behavioural oestrus, morphology of external genitalia and changes in the peripheral plasma concentrations of oestradiol and progestogen. The mean (+/- SEM) duration of the non-mated oestrous cycle and duration of oestrus in 12 koalas was 32.9 +/- 1.1 (n = 22) and 10.3 +/- 0.9 (n = 24) days, respectively. Although the commencement of oestrous behaviour was associated with increasing or high concentrations of oestradiol, there were no consistent changes in the morphology or appearance of the clitoris, pericloacal region, pouch or mammary teats that could be used to characterize the non-mated cycle. As progestogen concentrations remained at basal values throughout the interoestrous period, non-mated cycles were considered non-luteal and presumed anovulatory. After mating of the 12 koalas, six females gave birth with a mean (+/- SEM) gestation of 34.8 +/- 0.3 days, whereas the remaining six non-parturient females returned to oestrus 49.5 +/- 1. 0 days later. After mating, oestrous behaviour ceased and the progestogen profile showed a significant increase in both pregnant and non-parturient females, indicating that a luteal phase had been induced by the physical act of mating. Progestogen concentrations throughout the luteal phase of the pregnant females were significantly higher than those of non-parturient females. Parturition was associated with a decreasing concentration of progestogen, which was increased above that of basal concentrations until 7 days post partum.

Laparotomy for Abdominal Stab Wound With Combined Omental and Organ Evisceration: 10-Year Experience From a Major Trauma Centre in South Africa

2021 ◽  
pp. 000313482110318
Author(s):  
Victor Kong ◽  
Cynthia Cheung ◽  
Nigel Rajaretnam ◽  
Rohit Sarvepalli ◽  
William Xu ◽  
...  
Keyword(s):  
South Africa ◽  
Small Bowel ◽  
Large Bowel ◽  
Major Trauma ◽  
Stab Wound ◽  
Length Of Hospital Stay ◽  
Trauma Centre ◽  
Major Trauma Centre ◽  
The Mean ◽  
Overall Mortality

Introduction Combined omental and organ evisceration following anterior abdominal stab wound (SW) is uncommon and there is a paucity of literature describing the management and spectrum of injuries encountered at laparotomy. Methods A retrospective study was undertaken on all patients who presented with anterior abdominal SW involving combined omental and organ evisceration who underwent laparotomy over a 10-year period from January 2008 to January 2018 at a major trauma centre in South Africa. Results A total of 61 patients were eligible for inclusion and all underwent laparotomy: 87% male, mean age: 29 years. Ninety-two percent (56/61) had a positive laparotomy whilst 8% (5/61) underwent a negative procedure. Of the 56 positive laparotomies, 91% (51/56) were considered therapeutic and 9% (5/56) were non-therapeutic. In addition to omental evisceration, 59% (36/61) had eviscerated small bowel, 28% (17/61) had eviscerated colon and 13% (8/61) had eviscerated stomach. A total of 92 organ injuries were identified. The most commonly injured organs were small bowel, large bowel and stomach. The overall complication rate was 11%. Twelve percent (7/61) required intensive care unit admission. The mean length of hospital stay was 9 days. The overall mortality rate for all 61 patients was 2%. Conclusions The presence of combined omental and organ evisceration following abdominal SW mandates laparotomy. The small bowel, large bowel and stomach were the most commonly injured organs in this setting.

Tectono‐metamorphic setting and paragenetic sequence of Au‐U mineralisation in the Archaean Witwatersrand Basin, South Africa

1997 ◽  
Vol 44 (3) ◽  
pp. 353-371 ◽  
Author(s):  
L. J. Robb ◽  
E. G. Charlesworth ◽  
G. R. Drennan ◽  
R. L. Gibson ◽  
E. L. Tongu
Keyword(s):  
South Africa ◽  
Witwatersrand Basin ◽  
Paragenetic Sequence

scholarly journals 24-Hour Measurement of Gastric pH in Rural South Africa

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Alastair M. Sammon ◽  
Eugene J. Ndebia ◽  
Ekambaram Umapathy ◽  
Jehu E. Iputo
Keyword(s):  
South Africa ◽  
Ambulatory Monitoring ◽  
Duodenogastric Reflux ◽  
Lower Oesophageal Sphincter ◽  
Gastric Ph ◽  
Night Time ◽  
High Incidence ◽  
The Mean ◽  
H Pylori ◽  
High Level

Background. Previous studies have established norms of 24-hour gastric pH profiles for western countries. This study was designed to establish the pattern for a rural African population with a high incidence of oesophageal cancer.Methods. After lower oesophageal manometry a probe was placed 10 cm distal to the lower oesophageal sphincter. We carried out 24-hour ambulatory monitoring of gastric pH on 59 healthy subjects. This was satisfactorily completed on 26 female and 18 male (age 21–64, median 35) subjects in the Transkei region of South Africa.Results. The mean 24 hour gastric pH was 2.84 and the mean night-time pH was 3.7. 40 volunteers recorded a night-time pH reaching over 4. 33 volunteers recorded a night-time pH over 7. Night-time alkalinisation was present for 136.4 minutes (25th centile 22.8, 75th centile 208.1) at pH4 or over, and 79.3 (2.5, 122.7) minutes at pH7 or over. Episodes of rapid alkaline rise were 17 (10, 47). 21.1% of these occurred while supine. 35 of 36 tested subjects were positive forH. pyloriIgG.Conclusion. Gastric alkalinisation is common in Transkei, at a higher pH than that reported in other studies, and is sustained longer. Nighttime alkalinisation is frequent. This suggests a high level of duodenogastric reflux.

scholarly journals Prevalence of zinc deficiency among primary school children in a poor peri-urban informal settlement in South Africa

2010 ◽  
Vol 15 (1) ◽  
Author(s):  
Folake O. Samuel ◽  
Abdulkadir A. Egal ◽  
Wilna H. Oldewage-Theron ◽  
Carin E. Napier ◽  
Christine S. Venter
Keyword(s):  
Social Sciences ◽  
South Africa ◽  
Zinc Deficiency ◽  
Informal Settlement ◽  
Serum Zinc ◽  
Primary School Children ◽  
World Health ◽  
Food Sources ◽  
Cross Sectional ◽  
The Mean

This cross-sectional study assessed the risk of zinc deficiency in randomly selected children, aged between 7 and 11 years, living in a poor, peri-urban informal settlement in South Africa. Dietary intake of 149 respondents was evaluated by 24-hour recall and quantitative food frequency questionnaires. Anthropometric and biochemical indices of a subset of 113 were determined. Descriptive statistics, analysis of variance and Pearson correlations were computed using the Statistical Package for Social Sciences, version 14.0. Anthropometric data were analysed using the World Health Organization Anthro plus version 1.0.2 statistical software. Dietary data were analysed with FoodFinder® version 3. The mean age of the children was 9.0±1.1 years. Few zinc-rich sources appeared in the diet that was predominantly plant-based. Mean dietary zinc intake was 4.6±2.2 mg/day. The mean value of serum zinc was 66.4±21.5 µg/dL, with 46% of the children having values less than the 70 µg/dL cut-off. The findings indicate a high risk of zinc deficiency and suboptimal zinc status for the majority of this study population of children, possibly as a result of low consumption of food sources with high bioavailability of zinc, which invariably is a direct consequence of poverty and food insecurity.OpsommingDie doel van hierdie dwarsdeursnitstudie was die bepaling van die risiko van ’n sinktekort in ’n ewekansige steekproef van 7 tot 11 jaar-oue kinders, woonagtig in ’n arm, voorstedelike informele woonbuurt in Suid Afrika. Dieetinnames van 149 respondente is geëvalueer deur 24-uur herroep en kwantitatiewe voedselfrekwensie vraelyste. Antropometriese en biochemiese indikatore van ’n kleiner steekproef van 113 is ook bepaal. Beskrywende statistiek, analise van variansie en Pearsonkorrelasies is bepaal deur die Statistical Package for Social Sciences, uitgawe 14.0. Antropometriese data is geanaliseer deur die statistiese program, Anthro plus, uitgawe 1.0.2, van die Wêreld Gesondheid Organisasie. Dieetdata is met behulp van FoodFinder® uitgawe 3 geanaliseer. Die gemiddelde ouderdom van die kinders was 9.0±1.1 jaar. Min sinkryke voedselbronne is in die hoofsaaklik plantryke dieet waargeneem. Die gemiddelde sinkinname was 4.6±2.2 mg/dag en die gemiddelde serumsinkwaarde was 66.4±21.5 µg/dL, met 46% van die kinders se waardes onder die 70 µg/dL afsnypunt. Die bevindings dui op ’n hoë risiko vir sinktekort en suboptimale sinkstatus vir die meerderheid van hierdie kinders, moontlik as gevolg van die swak inname van voedselbronne met hoë biobeskikbare sink, wat gewoonlik ’n direkte gevolg van armoede en huishoudelike voedsel insekuriteit is.

scholarly journals Effect of Injection Pressure of Infiltration Anesthesia to the Jawbone

2016 ◽  
Vol 63 (3) ◽  
pp. 131-138 ◽  
Author(s):  
Kenji Yoshida ◽  
Eri Tanaka ◽  
Hiroyoshi Kawaai ◽  
Shinya Yamazaki
Keyword(s):  
Local Anesthetic ◽  
White Male ◽  
Injection Pressure ◽  
Time Interval ◽  
Time Intervals ◽  
Lidocaine Concentration ◽  
The Mean ◽  
High Concentrations ◽  
Infiltration Anesthesia ◽  
Local Anesthetic Infiltration

To obtain effective infiltration anesthesia in the jawbone, high concentrations of local anesthetic are needed. However, to reduce pain experienced by patients during local anesthetic administration, low-pressure injection is recommended for subperiosteal infiltration anesthesia. Currently, there are no studies regarding the effect of injection pressure on infiltration anesthesia, and a standard injection pressure has not been clearly determined. Hence, the effect of injection pressure of subperiosteal infiltration anesthesia on local anesthetic infiltration to the jawbone was considered by directly measuring lidocaine concentration in the jawbone. Japanese white male rabbits were used as test animals. After inducing general anesthesia with oxygen and sevoflurane, cannulation to the femoral artery was performed and arterial pressure was continuously recorded. Subperiosteal infiltration anesthesia was performed by injecting 0.5 mL of 2% lidocaine containing 1/80,000 adrenaline, and injection pressure was monitored by a pressure transducer for 40 seconds. After specified time intervals (10, 20, 30, 40, 50, and 60 minutes), jawbone and blood samples were collected, and the concentration of lidocaine at each time interval was measured. The mean injection pressure was divided into 4 groups (100 ± 50 mm Hg, 200 ± 50 mm Hg, 300 ± 50 mm Hg, and 400 ± 50 mm Hg), and comparison statistical analysis between these 4 groups was performed. No significant change in blood pressure during infiltration anesthesia was observed in any of the 4 groups. Lidocaine concentration in the blood and jawbone were highest 10 minutes after the infiltration anesthesia in all 4 groups and decreased thereafter. Lidocaine concentration in the jawbone increased as injection pressure increased, while serum lidocaine concentration was significantly lower. This suggests that when injection pressure of subperiosteal infiltration anesthesia is low, infiltration of local anesthetic to the jawbone may be reduced, while transfer to oral mucosa and blood may be increased.

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