A preliminary fish survey of the estuaries on the southeast coast of South Africa, Kayser’s Beach – Kei Mouth: a comparative study

A basic ichthyofaunal and physico-chemical survey of estuaries on the southeast coast of South Africa from Kayser’s Beach to Kei Mouth was undertaken during September and October 1996. Twenty-eight (28) estuaries have been identified along this stretch of coastline, and these were grouped into three types: small (<10 ha) predominantly closed estuaries, moderate to large (> 10 ha) predominantly closed estuaries, and predominantly open estuaries. Multivariate analyses revealed significant differences between estuarine types both in terms of their physico-chemical characteristics and fish communities. These features were consistent with those reported in other parts of the south and southeast coast. Overall, predominantly closed estuaries had a lower species diversity than predominantly open estuaries and smaller systems had a lower species diversity than moderate to large systems. Although differences were observed between estuarine types, most systems provided important habitat for a number of estuarine-dependent marine species as well as resident species, which were often recorded in high numbers. Many of these species were also endemic, which further emphasises the importance of these estuaries in maintaining ichthyofaunal diversity in the region. This survey represents one of the few fish surveys undertaken along this little-studied section of coastline.Keywords: ichthyofauna, estuarine survey, fish habitat, southeast coas

On the role of buoyant flexure in glacier calving

Interactions between glaciers and the ocean are key for understanding the dynamics of the cryosphere in the climate system. Here we investigate the role of hydrostatic forces in glacier calving. We develop a mathematical model to account for the elastic deformation of glaciers in response to three effects: (i) marine and lake-terminating glaciers tend to enter water with a nonzero slope, resulting in upward flexure around the grounding line; (ii) horizontal pressure imbalances at the terminus are known to cause hydrostatic in-plane stresses and downward acting torque; (iii) submerged ice protrusions at the glacier front may induce additional buoyancy forces that can cause calving. Our model provides theoretical estimates of the importance of each effect and suggests geometric and material conditions under which a given glacier will calve from hydrostatic flexure. We find good agreement with observations. This work sheds light on the intricate processes involved in glacier calving and can be hoped to improve our ability to model and predict future changes in the ice-climate system

Pulsed electromagnetic energy treatment offers no clinical benefit in reducing the pain of knee osteoarthritis: a systematic review

Background The rehabilitation of knee osteoarthritis often includes electrotherapeutic modalities as well as advice and exercise. One commonly used modality is pulsed electromagnetic field therapy (PEMF). PEMF uses electro magnetically generated fields to promote tissue repair and healing rates. Its equivocal benefit over placebo treatment has been previously suggested however recently a number of randomised controlled trials have been published that have allowed a systematic review to be conducted. Methods A systematic review of the literature from 1966 to 2005 was undertaken. Relevant computerised bibliographic databases were searched and papers reviewed independently by two reviewers for quality using validated criteria for assessment. The key outcomes of pain and functional disability were analysed with weighted and standardised mean differences being calculated. Results Five randomised controlled trials comparing PEMF with placebo were identified. The weighted mean differences of the five papers for improvement in pain and function, were small and their 95% confidence intervals included the null. Conclusion This systematic review provides further evidence that PEMF has little value in the management of knee osteoarthritis. There appears to be clear evidence for the recommendation that PEMF does not significantly reduce the pain of knee osteoarthritis

Metal-based imaging agents: progress towards interrogating neurodegenerative disease.

Central nervous system (CNS) neurodegeneration is defined by a complex series of pathological processes that ultimately lead to death. The precise etiology of these disorders remains unknown. Recent efforts show that a mechanistic understanding of the malfunctions underpinning disease progression will prove requisite in developing new treatments and cures. Transition metals and lanthanide ions display unique characteristics (i.e., magnetism, radioactivity, and luminescence), often with biological relevance, allowing for direct application in CNS focused imaging modalities. These techniques include positron emission tomography (PET), single-photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), and luminescent-based imaging (LumI). In this Tutorial Review, we have aimed to highlight the various metal-based imaging techniques developed in the effort to understand the pathophysiological processes associated with neurodegeneration. Each section has been divided so as to include an introduction to the particular imaging technique in question. This is then followed by a summary of key demonstrations that have enabled visualization of a specific neuropathological biomarker. These strategies have either exploited the high binding affinity of a receptor for its corresponding biomarker or a specific molecular transformation caused by a target species, all of which produce a concomitant change in diagnostic signal. Advantages and disadvantages of each method with perspectives on the utility of molecular imaging agents for understanding the complexities of neurodegenerative disease are discussed

Andersen-Tawil Syndrome Presenting with Complete Heart Block

Andersen-Tawil syndrome (ATS) is a rare autosomal dominant neuromuscular disorder due to mutations in the KCNJ2 gene. The classical phenotype of ATS consists of a triad of periodic paralysis, cardiac conduction abnormalities and dysmorphic features. Episodes of either muscle weakness or cardiac arrhythmia may predominate however, and dysmorphic features may be subtle, masking the true breadth of the clinical presentation, and posing a diagnostic challenge. The severity of cardiac involvement varies but includes reports of life-threatening events or sudden cardiac death, usually attributed to ventricular tachyarrhythmias. We report the first case of advanced atrioventricular (AV) block in ATS and highlight clinical factors that may delay diagnosis

Modeling the Adaptive Role of Negative Signaling in Honey Bee Intraspecific Competition

Collective decision making in the social insects often proceeds via feedback cycles based on positive signaling. Negative signals have, however, been found in a few contexts in which costs exist for paying attention to no longer useful information. Here we incorporate new research on the specificity and context of the negative stop signal into an agent based model of honey bee foraging to explore the adaptive basis of negative signaling in the dance language. Our work suggests that the stop signal, by acting as a counterbalance to the waggle dance, allows colonies to rapidly shut down attacks on other colonies. This could be a key adaptation, as the costs of attacking a colony strong enough to defend itself are significant

The SCottish Alcoholic Liver disease Evaluation: a population-level matched cohort study of hospital-based costs, 1991-2011

Studies assessing the costs of alcoholic liver disease are lacking. We aimed to calculate the costs of hospitalisations before and after diagnosis compared to population controls matched by age, sex and socio-economic deprivation. We aimed to use population level data to identify a cohort of individuals hospitalised for the first time with alcoholic liver disease in Scotland between 1991 and 2011.Incident cases were classified by disease severity, sex, age group, socio-economic deprivation and year of index admission. 5 matched controls for every incident case were identified from the Scottish population level primary care database. Hospital costs were calculated for both cases and controls using length of stay from morbidity records and hospital-specific daily rates by specialty. Remaining lifetime costs were estimated using parametric survival models and predicted annual costs. 35,208 incident alcoholic liver disease hospitalisations were identified. Mean annual hospital costs for cases were 2.3 times that of controls pre diagnosis (£804 higher) and 10.2 times (£12,774 higher) post diagnosis. Mean incident admission cost was £6,663. Remaining lifetime cost for a male, 50-59 years old, living in the most deprived area diagnosed with acoholic liver disease was estimated to be £65,999 higher than the matched controls (£12,474 for 7.43 years remaining life compared to £1,224 for 21.8 years). In Scotland, alcoholic liver disease diagnosis is associated with significant increases in admissions to hospital both before and after diagnosis. Our results provide robust population level estimates of costs of alcoholic liver disease for the purposes of health-care delivery, planning and future cost-effectiveness analyses

Impaired myocardial function does not explain reduced left ventricular filling and stroke volume at rest or during exercise at high altitude

Impaired myocardial systolic contraction and diastolic relaxation have been suggested as possible mechanisms contributing to the decreased stroke volume (SV) observed at high altitude (HA). To determine whether intrinsic myocardial performance is a limiting factor in the generation of SV at HA, we assessed left ventricular (LV) systolic and diastolic mechanics and volumes in 10 healthy participants (aged 32 ± 7; mean ± SD) at rest and during exercise at sea level (SL; 344 m) and after 10 days at 5,050 m. In contrast to SL, LV end-diastolic volume was ∼19% lower at rest (P = 0.004) and did not increase during exercise despite a greater untwisting velocity. Furthermore, resting SV was lower at HA (∼17%; 60 ± 10 vs. 70 ± 8 ml) despite higher LV twist (43%), apical rotation (115%), and circumferential strain (17%). With exercise at HA, the increase in SV was limited (12 vs. 22 ml at SL), and LV apical rotation failed to augment. For the first time, we have demonstrated that EDV does not increase upon exercise at high altitude despite enhanced in vivo diastolic relaxation. The increase in LV mechanics at rest may represent a mechanism by which SV is defended in the presence of a reduced EDV. However, likely because of the higher LV mechanics at rest, no further increase was observed up to 50% peak power. Consequently, although hypoxia does not suppress systolic function per se, the capacity to increase SV through greater deformation during submaximal exercise at HA is restricted. during initial exposure to hypobaric hypoxia at high altitude (HA), cardiac output for a given absolute workload is increased to compensate for a lower arterial oxygen content before returning to baseline levels with acclimatization (8). However, after 2-5 days of acclimatization, the required cardiac output is generated through a lower stroke volume (SV) and higher heart rate (38). The reduced SV is suggestive of either lower ventricular filling, potentially caused in part by an impaired myocardial relaxation, or impaired ejection secondary to systolic contractile dysfunction. There is, however, a paucity of data in humans supporting a direct effect of hypoxia on myocardial function at HA (25, 41). The suggestion that hypoxia may impair myocardial systolic function during exercise was proposed nearly 50 years ago (3) and has been revisited more recently (27–29). Negative inotropic effects of hypoxia (arterial oxygen tension of 44 mmHg) have been shown in intact animal models (39) and isolated myocardial fibers under severe hypoxia (1% O2) (33). Exercise training under hypobaric hypoxia is also associated with altered mechanical properties at a cellular level in rodents (9), although chronic hypoxia alone did not decrease myofilament sensitivity to calcium. However, in contrast to animal studies, data in humans indicate that systolic function is maintained or enhanced at HA. For example, Suarez et al. (37) reported the maintenance of systolic function after gradual decompression to a barometric pressure of 282 mmHg, a finding that was subsequently confirmed by numerous investigations during acute and prolonged hypoxic exposure (6, 10, 12, 23, 31). However, of these studies, only Suarez et al. (37) investigated systolic function during light exercise (60 W), where function appeared to be maintained. It is not known whether systolic function is maintained at higher exercise intensities. It has also been speculated that reduced oxygen availability may impair diastolic relaxation at HA (15, 18) and thus explain the decreased left ventricular (LV) end-diastolic volume (EDV) commonly observed (2, 6, 18). However, despite numerous studies reporting a decrease in plasma volume and altered transmitral filling patterns (2, 6, 20), myocardial relaxation was only previously investigated during hypoxia in dogs (15), and no data exist examining LV relaxation during exercise at high altitude. By using sensitive, noninvasive imaging techniques (two-dimensional speckle tracking), it is now possible to examine the LV deformation mechanics (strain, twist, and untwist velocity) that underpin LV systolic and diastolic function. LV strain and twist have been shown to be sensitive measures of global and regional myocardial function, and reveal subclinical dysfunction in patients where ejection fraction is unchanged (16, 22). In addition, diastolic LV untwist velocity correlates well with invasive measures of LV stiffness and provides a temporal link between relaxation and the development of intraventricular pressure gradients (30, 43). Therefore, examination of LV mechanics at HA may determine whether the decreased SV observed at HA is dependent on impaired myocardial relaxation and/or myocardial contractile dysfunction or confirm previous findings of preserved ventricular function during exercise (37). We therefore assessed systolic and diastolic ventricular mechanics during incremental exercise at sea level and HA to examine whether impaired myocardial relaxation or systolic dysfunction explains the previously reported reduction in SV at HA. We hypothesized that at HA, 1) ventricular filling would be lower at rest and during exercise and would be accompanied by a reduction in untwist velocity and 2) systolic mechanics would be impaired during exercise at HA

Influence of Exposure to Imidacloprid on Survivorship, Reproduction and Vitellin Content of the Carmine Spider Mite, Tetranychus cinnabarinus

Occasional reports linking neonicotinoid insecticide applications to field population outbreaks of the spider mite have been a topic of concern for integrated pest management programs. To elucidate the impacts of a neonicotinoid insecticide on the carmine spider mite, Tetranychus cinnabarinus Boisduval (Acari: Tetranychidae), the survivorship, reproduction, and vitellin contents of the mite were investigated after exposure to various concentrations of imidacloprid on the V. unguiculata leaf discs at 25°C, 80% RH and a photoperiod of 14:10 (L:D) in the laboratory. The results showed that the field-relevant dose of imidacloprid did not significantly affect the hatch rate of eggs or pre-imaginal survivorship of the mite, while sublethal doses of imidacloprid, previously determined for Myzus persicae, led to a significant increase in the hatch rate of eggs and pre-imaginal survivorship of the mite compared to the untreated control. Adult longevity and fecundity of T. cinnabarinus for imidacloprid-treated populations were slightly prolonged and increased, respectively, but the difference from the untreated control was not significant. The vitellin content in eggs increased significantly after exposure to imidacloprid. Imidacloprid may be one of the major reasons for the outbreak of T. cinnabarinus in the field