Gunshot injuries of the spine

The Acute Spinal Injury Unit, relocated from Conradie Hospital to Groote Schuur Hospital in mid-2003, admitted 162 patients in the first year of its existence. A large number of these injuries were the result of interpersonal violence, particularly gunshot wounds. Aim. To review patients with gunshot injuries to the spine, with reference to neurological injury, associated injuries, need for surgery and complications. Methods. A comprehensive database is maintained to collect data on all spinal injury admissions. These data, as well as case notes and X-rays, were reviewed for all gunshot spine patients admitted to the Acute Spinal Injury Unit over a year. Forty-nine patients were identified. Thirty-eight were male and 11 female with an average age of 27.5 years (range 15 - 51 ± 8.53). The average stay in the acute unit was 30 (4 - 109 ± 28) days. Results. The spinal injury was complete in 38 and incomplete in 8, with 3 having no neurological deficit. The level was cervical in 13, thoracic in 24 and lumbar in 12. Only 9 patients improved neurologically. The spine was considered stable in 43 cases. Stabilisation was performed in the 6 unstable cases. The bullets were removed in 11 cases as they were in the canal. There were 55 significant associated injuries, viz. 14 haemo-pneumothoraces, 16 abdominal visceral injuries, 3 vascular injuries, 4 injuries of the brachial plexus and 3 of the oesophagus, 2 tracheal injuries, 1 soft palate injury and 11 non-spinal fractures. Complications included 3 deaths and discitis in 3 cases, pneumonia in 6 and pressure sores in 6. Conclusion. Gunshot injuries of the spine are a prevalent and resource-intensive cause of paralysis. There is a high incidence of permanent severe neurological deficit, but usually the spine remains mechanically stable. Most of the management revolves around the associated injuries and consequences of the neurological deficit

A grammatical analysis of the Tswana adverbial

Adverbial constructions are a problematic subject in Tswana grammatical studies. Traditionally termed descriptives, it is not clear what the defining features of this category are. It is also a very vast category. There seems to be many different structures functioning as adverbials in Tswana, including particles, words, prepositional phrases and clauses. Tswana grammars in general often have little to say about the syntax of adverbials, in respect of, for instance, the propensity of Tswana adverbials for multiple occurrences in the same clause and the range of possible positions of Tswana adverbials in clause structure. Because of the vastness of the adverbial category we only deal with adverbials as elements of clause structure. A typical feature of adverbials is the considerable mobility they enjoy in relation to other elements in clause structure which affects their grammatical and semantic status in relation to such elements. By distinguishing different categories of adverbials, in clause structure it becomes clear that the same structural element may function within different adverbial categories. This necessitates a definition of adverbials which is based on their specific semantic functions within clause structure. The study is divided into five chapters. When dealing with the adverbial as a clause element in Tswana, we realise that it is not sufficiently described. The first two chapters therefore serve as an introduction to central theoretical issues where some relevant research is critically examined and related to the present study. In the next chapter, that is Chapter 3, we establish formal and semantic frameworks for the classification and descriptive treatment of adverbials in Tswana. In Chapter 4 we implement the structural, syntactic and semantic properties as well as the features adverbials have as modifiers to make a functional classification of adverbials in clause structure. The classification of adverbials as adjuncts, subjuncts, disjuncts and conjuncts from A Comprehensive grammar of the English language by Quirk, et al. (1985) (CGEL) is taken as the basis for this classification. Chapter 5 presents the overall conclusions and implications of the study.African LanguagesD.litt. et Phil. (African Languages

Occurrence and extent of hybridisation between the invasive Mallard Duck and native Yellow-billed Duck in South Africa

Hybridisation between invasive and native species represents a significant threat to biodiversity. The Mallard Duck (Anas platyrhynchos) is known to hybridise with numerous closely related Anas species in regions where they have been introduced, threatening the genetic integrity of native ducks and in some instances contributing to their extinction risk. Mallard Ducks were introduced into South Africa in the 1940s and are now naturalised and widespread in the country. It has been speculated that Mallard Ducks are hybridising with native Yellow-billed Ducks (A. undulata) in South Africa, but evidence for this remains observational or purely anecdotal. Here we use data from nuclear microsatellite markers and mitochondrial DNA sequencing to show that hybridisation is indeed occuring between these two species. We found evidence for the occurance of hybridisation, mostly as crosses between Mallard Duck hens and Yellow-billed Duck drakes. Surprisingly, our results suggest that introgressive hybridisation is primarily occuring into the invasive Mallard Duck population (mostly Mallard Duck backcrosses were detected), evidenced by directionally-skewed gene flow and sex-biased mating. Whether these findings reflect true assortative mating or a case of Haldane’s rule remains unknown. We also found evidence of high connectivity between Yellow-billed Duck populations, as far as 1000 km apart, in South Africa. Taken together these results suggest that hybrid genotypes can disperse over vast distances between populations and lead to genetic pollution, even in the absence of invasive Mallard Ducks. Active management of Mallard Duck populations has been met by public resistance in some areas in South Africa, partly because of a lack of evidence showing clear impacts by these birds. This study provides some of the first scientifically-documented evidence for such impacts

Female philopatry and dominance patterns in wild geladas

Cercopithecines have a highly conserved social structure with strong female bonds and stable, maternally inherited linear dominance hierarchies. This system has been ascribed to the pervasiveness of female philopatry within the typical multi-male, multi-female social groups. We examined the relationship between female philopatry, dominance hierarchies, and reproduction in geladas ( Theropithecus gelada ), a species with an unusual multi-leveled society. During a 4-year field study on a wild population in the Simien Mountains National Park, Ethiopia, we observed 14 units across two bands of geladas that underwent a number of events, such as male takeovers and female deaths, which could potentially disrupt female relationships and unit structure. First, we corroborate earlier reports that gelada females are natally philopatric: we observed no interunit migrations, and the female mortality rate was comparable to that of philopatric baboons (suggesting all female disappearances were indeed deaths). Second, contrary to previous reports, data from this long-term study show that geladas exhibit the linear and stable dominance hierarchies typical of other Cercopithecines. Moreover, female ranks appear to be maternally inherited. Third, we found no evidence that alpha females aggressively target the lowest ranking individuals, nor did rank confer clear reproductive advantages to dominant females within our 4-year observation period. As such, geladas fit the allostatic load model [Goymann & Wingfield, Animal Behaviour 67:591–602, 2004]. Our study confirms the importance of female philopatry in the kin-based Cercopithecine dominance system. Am. J. Primatol. 73:422–430, 2011. © 2010 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83472/1/20916_ftp.pd

Cosmic rays beyond the boundary of the heliosphere

In August of 2012 the Voyager 1 space probe has left the solar-wind bubble of ionized gas we call the heliosphere and entered the denser and colder environment of the interstellar cloud surrounding the solar system. Energetic charged particles underwent dramatic changes past the heliopause: the heliospheric ions disappeared completely, while the galactic cosmic rays were for the first time measured in their unmodulated state. The interstellar medium turned out to be almost entirely devoid of turbulent magnetic fluctuations, therefore the transport of cosmic rays is governed by a large-scale geometry of the magnetic field. We discuss observations of heliospheric ions, including anomalous cosmic rays, near the heliopause transition, and propose interpretations of the measured intensities and pitch-angle distributions based on gradient drift in a weakly nonuniform magnetic field. The heliopause transition appears to be permeated by magnetic flux tubes connected to the interstellar space and facilitating particle escape. These flux tubes may be a product of interchange instability driven by a plasma pressure gradient across the heliopause. The curvature of magnetic field lines and the anti-sunward gradient in plasma kinetic pressure provide conditions favorable for an interchange. The two flux tube crossings by the spacecraft allowed an indirect measurement of the plasma radial velocity near the heliopause

Energetic Particle Anisotropies at the Heliospheric Boundary. II. Transient Features and Rigidity Dependence

In the preceding paper, we showed that large second-order anisotropies of heliospheric ions measured by the Voyager 1 space probe during the August 2012 boundary crossing event could be explained by a magnetic shear across the heliopause preventing particles streaming along the magnetic field from escaping the inner heliosheath. According to Stone et al., the penetration distance of heliospheric ions into the outer heliosheath had a strong dependence on the particle's Larmor radius. By comparing hydrogen, helium, and oxygen ions with the same energy per nucleon, these authors argued that this effect must be attributed to larger cyclotron radii of heavier species rather than differences in velocity. We propose that gradient drift in a nonuniform magnetic field was the cause of both the large second-order anisotropies and the spatial differentiation based on the ion's rigidity. A latitudinal gradient of magnetic field strength of about 10% per AU between 2012.7 and 2012.9 could have provided drift motion sufficient to match both LECP and CRS Voyager 1 observations. We explain the transient intensity dropout observed prior to the heliocliff using flux tube structures embedded in the heliosheath and magnetically connected to interstellar space. Finally, this paper reports a new indirect measurement of the plasma radial velocity at the heliopause on the basis of the time difference between two cosmic-ray telescopes measuring the same intensity dropout

Intertwining Laplace Transformations of Linear Partial Differential Equations

We propose a generalization of Laplace transformations to the case of linear partial differential operators (LPDOs) of arbitrary order in R^n. Practically all previously proposed differential transformations of LPDOs are particular cases of this transformation (intertwining Laplace transformation, ILT). We give a complete algorithm of construction of ILT and describe the classes of operators in R^n suitable for this transformation. Keywords: Integration of linear partial differential equations, Laplace transformation, differential transformationComment: LaTeX, 25 pages v2: minor misprints correcte

Prenatal evaluation of kidney function in mice using dynamic contrast-enhanced magnetic resonance imaging

Glomerular differentiation starts as soon as embryonic stage 12 in mice and suggests that kidneys may be functional at this stage. Dynamic contrast-enhanced magnetic resonance microscopy, a noninvasive imaging technique, was used to assess renal function establishment in utero. Indeed, in adults (n = 3), an intravenous injection of gadolinium-DOTA induced in a first step a massive and rapid drop in kidney signal intensity followed, in a second step, by a drop in bladder signal intensity. The delay in signal changes between kidney and bladder reflected glomerular filtration. Pregnant mice underwent anatomical and dynamic contrast-enhanced magnetic resonance microscopy on postcoital days 12-13 (n = 2), 13-14 (n = 1), 14-15 (n = 3), 15-16 (n = 2), 16-17 (n = 3), 17-18 (n = 3), and 18-19 (n = 1). Kidneys and bladder were unambiguously depicted prior to contrast agent injection on stage 15-16 embryos. Contrast agent injection allowed kidney, detection as early as stage 12-13 but not bladder. Kinetics of signal changes demonstrated that glomerular filtration is established at embryonic stage 15-16 in mice. Thus, anatomical and dynamic contrast-enhanced magnetic resonance microscopy may be a powerful noninvasive method for in vivo prenatal developmental and functional studies

Vitellogenesis as a biomarker for estrogenic contamination of the aquatic environment

A rapidly increasing number of chemicals, or their degradation products, are being recognized as possessing estrogenic activity, albeit usually weak. We have found that effluent from sewage treatment works contains a chemical, or mixture of chemicals, that induces vitellogenin synthesis in male fish maintained in the effluent, thus indicating that the effluent is estrogenic. The effect was extremely pronounced and occurred at all sewage treatment works tested. The nature of the chemical or chemicals causing the effect is presently not known. However, we have tested a number of chemicals known to be estrogenic to mammals and have shown that they are also estrogenic to fish; that is, no species specificity was apparent. Many of these weakly estrogenic chemicals are known to be present in effluents. Further, a mixture of different estrogenic chemicals was considerably more potent than each of the chemicals when tested individually, suggesting that enhanced effects could occur when fish are exposed simultaneously to various estrogenic chemicals (as is likely to occur in rivers receiving effluent). Subsequent work should determine whether exposure to these chemicals at the concentrations present in the environment leads to any deleterious physiological effects