Burrow architecture of the Damaraland mole-rat (Fukomys damarensis) from South Africa

The burrow architecture (length, internal dimensions, fractal dimension of tunnel systems, number of nesting chambers and surface mounds) was investigated in the Damaraland mole-rat (Fukomys damarensis). A total of 31 animals were caught from five different colonies and their burrow systems were excavated in their entirety. The mean and SD colony size was 6 ± 3.3, with a range of 2-10 mole-rats. The sex ratio was male biased 1.21:1. Males had a body mass of 80.5 ± 33.8g, but were not significantly different to those of females which had a mean body mass of 83.4 ± 24.9g. The burrow system of the Damaraland mole-rats follows the same general architectural plan as recorded for other species of mole-rat with either one or two more centrally based deeper more permanent burrows which often connect to a nest area, which is used for resting and rearing offspring. The burrow systems contained several more superficial secondary tunnels at a shallower depth. The secondary tunnels accounted for up to 80% of the total burrow system. The mean length of the burrow system was 130.4m and covered an area of 1403m². The mean number of secondary branches in a burrow system was 10. The mean fractal dimension was 1.154 which implies the mole-rats do not explore their surrounding environment particularly efficiently when compared to that of other mole-rat species, but this may relate to the size of the main food resource, the Eland bean (Elephantorrhiza elephantina) which is randomly distributed and fed on in situ. Our study showed that colony size influences the size and complexity of the burrow system with larger colonies having a longer burrow system covering a greater area with more secondary tunnels than that of smaller colonies.The University of Pretoria, by the SARChI Chair of Mammal Behavioural Ecology and Physiology and by the National Research Foundation, South Africa to NCB.http://www.nisc.co.za/products/59/journals/african-zoology2017-04-30hb2016Zoology and Entomolog

Seasonal effects on digging activity and burrow architecture in the Cape dune mole-rat, Bathyergus suillus (Rodentia : Bathyergidae)

Most polygynous male mammals exhibit little or no parental care or involvement raising young. Instead, they invest indirectly in their own morphological and physiological attributes which enhance their chance of reproduction. Such secondary morphological sex traits may contribute to differences in the burrow architecture of fossorial mammals, such as the Cape dune mole-rat, Bathyergus suillus. Indeed, little is known about the seasonal changes in burrow architecture or differences in burrow configuration may differ between the sexes of subterranean African mole-rats (Bathyergidae). We excavated burrow systems of male and female B. suillus during the summer and the winter to investigate whether male burrow architecture reflected putative mate-seeking behaviour. We consider burrow geometry in response to mating strategies. Male burrow systems explored the environment more efficiently than females. This is presumably because of the increase in associated energetic costs of being a large male. Males produce more mounds indicating territorial behaviour even when it is energetically costly to dispose of soil onto the surface when the soil is less friable during the summer. Overall tunnel dimensions did not differ between the sexes. It appears that a change in season does not affect the geometry of the burrow system or tunnel dimensions in a climatically buffered environment.University of Pretoria, by the SARChI Chair of Mammal Behavioural Ecology and Physiology and by the National Research Foundation, South Africa to N.C.B.http://africanzoology.journals.ac.za/am2013ab201

Season but not sex influences burrow length and complexity in the non-sexually dimorphic solitary Cape mole-rat (Rodentia : Bathyergidae)

Little is known about how environmental factors such as season influence burrowing activity, burrow structure or reproductive behaviour in subterranean mammals. We excavated burrow systems of male and female Georychus capensis, a solitary, subterranean rodent, in winter (wet season) and summer (dry season) to investigate whether any seasonal differences due to putative mate-seeking behaviour of males were apparent. Burrow structure did not differ between sexes, but did differ between seasons. For both sexes, summer burrows were shorter in length and covered a smaller area but explored the surrounding environment more efficiently than did winter burrows. Summer burrows had fewer mounds present indicating less expansion of the burrow systems in this season. We discuss these differences in exploration and use of the environment between seasons but not between sexes in terms of mating strategies of G. capensis and observed levels of sexual dimorphism in our populations. This study supports recent concepts regarding female competition and selection that may favour the expression of female exaggerated traits, which affect a female’s ability to acquire reproductive resources that often appear similar to that selected for by males.This research was supported by the University of Pretoria, by the SARChI Chair of Behavioural Ecology and Physiology and by the National Research Foundation, South Africa to NCB.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-7998hb2016Mammal Research InstituteZoology and Entomolog

Seasonal changes in burrow geometry of the common mole rat (Rodentia: Bathyergidae)

Sociality in mole rats has been suggested to have evolved as a response to the widely dispersed food resources and the limited burrowing opportunities that result from sporadic rainfall events. In the most arid regions, individual foraging efficiency is reduced, and energetic constraints increase. In this study, we investigate seasonal differences in burrow architecture of the social Cryptomys hottentotus hottentotus in a mesic region. We describe burrow geometry in response to seasonal weather conditions for two seasons (wet and dry). Interactions occurred between seasons and colony size for the size of the burrow systems, but not the shape of the burrow systems. The fractal dimension values of the burrow systems did not differ between seasons. Thus, the burrow complexity was dependent upon the number of mole rats present in the social group.The University of Pretoria, by the SARChI Chair of Mammal Behavioural Ecology and Physiology and by the National Research Foundation, South Africa to NCB.http://link.springer.com/journal/114hj201

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Seasonal patterns of burrow architecture and morphological adaptations to digging in three sympatric species of South African mole-rat, Bathyergus suillus (Shreber, 1782), Georychus capensis (Pallas, 1778) and Cryptomys hottentotus hottentotus (Lesson, 1826)

Mammals use burrows for numerous functions. As these functions become more complex so does the burrow system. Although this underground environment is buffered from many climatic factors, it does pose an energetically expensive way of life. Due to the increased energy expenditure that is needed to forage and live underground, most subterranean mammals have evolved morphological adaptations to living in such a specialised environment. To this end, the burrow systems of three different African mole rats were considered, which range in body size, sociality and apparent foraging behaviour. Bathyergus suillus excavate their burrow systems using their enlarged forelimbs. Their burrow systems generally have one or two main, deeper, central tunnels that connect to a varying number of shallow 'foraging' tunnels in both sexes. In this study, winter burrow geometry did not differ from summer burrow geometry. The fractal dimension and thus habitat exploration differed with sex; males exploring the environment more efficiently than females. The burrows of G. capensis did not differ with the sex of the occupant but rather with season. The burrows in winter were generally longer and covered a greater area, but they did not necessarily explore the surrounding environment any more efficiently than burrows in summer. The lack of difference in burrow geometry coupled with the sexual dimorphism of the skull (reverse sexual size dimorphism) indicates that an alternative mating strategy may be employed by G. capensis compared to other species of mole-rats. Finally, Cryptomys hottentotus hottentotus create elaborate multi-layered burrow systems with numerous foraging tunnels and a few central deep tunnels. The burrow systems in this case differed between the winter and summer. Burrows in the winter were generally longer, covered a greater area and had more branching of the tunnels than those burrows in the summer, i.e. were more efficient. Burrow size appears to be dependent upon colony size; the larger the colony, the larger and the more branching the burrow system. At a glance the mole-rats face suggests that their incisors may play a special role in mole-rat behaviour. Mole-rats move objects, excavate burrows, carry young, eat and display in social interactions using external procumbent incisors. Mole-rats also use their incisors as a somatosensory organ and Cryptomys h. hottentotus has been suggested to use its incisors to sense vibrations (Poduschka, 1978). This study revealed no evidence of sexual dimorphism in bite force even within solitary species that have marked sexual size dimorphism. Bite force does not appear to be allometric to body size as previously reported in other studies. Macro-anatomical osteological descriptions are non-existent for South African mole-rats. Within the forelimb, the skeletal system has presumably adapted to withstand the greater pressures exerted due to the excavation methods employed by the mole-rats. To this end, the forelimb bones are generally more robust and have larger areas than terrestrial rodents with more tuberosities for extra muscle attachment to enable them to dig proficiently.Thesis (PhD)--University of Pretoria, 2013.Zoology and EntomologyUnrestricte

Exploring the cost-effectiveness of high versus low perioperative fraction of inspired oxygen in the prevention of surgical site infections among abdominal surgery patients in three low- and middle-income countries

Background: This study assessed the potential cost-effectiveness of high (80–100%) vs low (21–35%) fraction of inspired oxygen (FiO2) at preventing surgical site infections (SSIs) after abdominal surgery in Nigeria, India, and South Africa. Methods: Decision-analytic models were constructed using best available evidence sourced from unbundled data of an ongoing pilot trial assessing the effectiveness of high FiO2, published literature, and a cost survey in Nigeria, India, and South Africa. Effectiveness was measured as percentage of SSIs at 30 days after surgery, a healthcare perspective was adopted, and costs were reported in US dollars ($). Results: High FiO2 may be cost-effective (cheaper and effective). In Nigeria, the average cost for high FiO2 was$216 compared with $222 for low FiO2 leading to a −$6 (95% confidence interval [CI]: −$13 to −$1) difference in costs. In India, the average cost for high FiO2 was $184 compared with$195 for low FiO2 leading to a −$11 (95$15 to −$6) difference in costs. In South Africa, the average cost for high FiO2 was$1164 compared with $1257 for low FiO2 leading to a −$93 (95% CI: −$132 to −$65) difference in costs. The high FiO2 arm had few SSIs, 7.33% compared with 8.38% for low FiO2, leading to a −1.05 (95% CI: −1.14 to −0.90) percentage point reduction in SSIs. Conclusion: High FiO2 could be cost-effective at preventing SSIs in the three countries but further data from large clinical trials are required to confirm this