The static allometry of sexual and non-sexual traits in vervet monkeys

Sexual traits vary tremendously in static allometry. This variation may be explained in part by body size-related differences in the strength of selection. We tested this hypothesis in two populations of vervet monkeys, using estimates of the level of condition dependence for different morphological traits as a proxy for body size-related variation in the strength of selection. In support of the hypothesis, we found that the steepness of allometric slopes increased with the level of condition dependence. One trait of particular interest, the penis, had shallow allometric slopes and low levels of condition dependence, in agreement with one of the most consistent patterns yet detected in the study of allometry, namely that of genitalia exhibiting shallow allometries.This research was supported by NIH grant R01RR0163009

Conceptualizing human resilience in the face of the global epidemiology of cyber attacks

Computer security is a complex global phenomenon where different populations interact, and the infection of one person creates risk for another. Given the dynamics and scope of cyber campaigns, studies of local resilience without reference to global populations are inadequate. In this paper we describe a set of minimal requirements for implementing a global epidemiological infrastructure to understand and respond to large-scale computer security outbreaks. We enumerate the relevant dimensions, the applicable measurement tools, and define a systematic approach to evaluate cyber security resilience. From the experience in conceptualizing and designing a cross-national coordinated phishing resilience evaluation we describe the cultural, logistic, and regulatory challenges to this proposed public health approach to global computer assault resilience. We conclude that mechanisms for systematic evaluations of global attacks and the resilience against those attacks exist. Coordinated global science is needed to address organised global ecrime

Lexicographic cones and the ordered projective tensor product

We introduce lexicographic cones, a method of assigning an ordered vector space \Lex(S) to a poset $S$, generalising the standard lexicographic cone. These lexicographic cones are then used to prove that the projective tensor cone of two arbitrary cones is a cone, and to find a new characterisation of finite-dimensional vector lattices.Comment: 8 page

The absence of diffusion in the South African short rate

In the field of Financial Mathematics, stochastic differential equations are used to describe the dynamics of interest rates. An example is a model for the short rate, which is a mathematically defined rate not directly observable in any market. However, observable rates such as short dated Treasury rates or the Johannesburg Interbank Agreement Rate (JIBAR) can be used as proxies for the short rate.The short rate dynamics are traditionally modelled by one-factor diffusion processes. These type of models remain popular due to the analytical tractability of the pricing formulae of interest rate derivatives under these models. To capture the leptokurtic nature of interest rate returns in the South African market, two types of models can be used: a pure jump model or a jump diffusion model. In this paper we investigate whether jumps are present and whether a diffusion component is evident. Our initial investigation showed that jumps were present in the South African market, and that no diffusion component was evident at low interest rate levels. This result was found using a Monte Carlo method to test for jumps. We therefore conclude that a pure jump process is an appropriate model for the South African short rate

Effects on mortality of a nutritional intervention for malnourished HIV-infected adults referred for antiretroviral therapy: a randomised controlled trial.

Malnourished HIV-infected African adults are at high risk of early mortality after starting antiretroviral therapy (ART). We hypothesized that short-course, high-dose vitamin and mineral supplementation in lipid nutritional supplements would decrease mortality

Multidisciplinary Training to Undergraduate Students in the Faculty of Health Sciences: Hypertension as a Case Study

Background: Healthcare students should be aware of the specific skills, knowledge and management options of other disciplines in order to achieve an effective and cohesive working relationship. Aim: The aim of this study was to expose healthcare students at the University of the Free State to one another\'s domains, as related to hypertension management, during a formal didactic lecture attended by medical, physiotherapy and dietetic students, and to determine whether they could apply in practice the theoretical knowledge regarding blood pressure measurement and exercise, obtained during a multidisciplinary session. The perceptions of students regarding multidisciplinary sessions were also to be obtained. Method: Students received a formal lecture on hypertension from a medical doctor, a dietitian, a physiotherapist and an occupational therapist and they then worked in multidisciplinary groups to demonstrate the physiological effect of exercise on blood pressure and pulse rate. Students had to report their findings and perceptions of the session by completing data forms. Results: A total of 125 medical, physiotherapy and human nutrition students participated in the session. The students were able to demonstrate the influence of exercise on blood pressure and pulse measurements. They reported that they enjoyed the multidisciplinary session and gained information on the scope of practice of the domains of the other disciplines. Negative feedback was received on the size of the groups and lack of equipment. Conclusion: The students could apply theoretical knowledge in practice and all gave positive feedback. The sessions will continue in the current format but attention will be given to smaller groups and the availability of more equipment. South African Journal of Family Practice Vol. 50 (4) 2008: pp. 70a-70

Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure

Investigating the use of bioimpedance to identify the epidural space.

Thesis (MEng)--Stellenbosch University, 2023.ENGLISH ABSTRACT: The complexity of performing an epidural procedure and locating the epidural space is well known as it requires physicians to rely on their knowledge of human anatomy and experience to succeed. This approach may be trustworthy, but it is subjective. As a result, two methods are developed and tested to assist in guiding a needle towards the epidural space. The design proposed in this document identifies and designs a system capable of identifying the epidural space and indicating when the needle-tip has made contact with the epidural space. The results from the theoretical investigative procedures and preliminary simulated study provides the foundation for yielding fully motivated decisions about the final experimental testing phase. Identifying the needle insertion site is the first step in guiding the needle to the epidural space. Near-infrared (NIR) light transmitted from a close distance through optical fibers can be used to locate the epidural space form outside the body. However, the simulated results show that this will not be possible as the detection range of the NIR sensor is less than the depth of the epidural space. To identify when the needle enters the epidural space, electrical impedance is measured through in-vitro experiments using gelatinous phantoms and porcine models. The outcomes of the experimental studies are similar to that obtained though the mathematical simulations. At 29.5 kHz, it is discovered through the biological tissue studies that the epidural space can be easily discriminated from subcutaneous fat, muscle and ligament. A statistically significant difference between the impedance of the epidural space and fat, muscle and ligament at 29.5 kHz is demonstrated by the data (p < 0.05). This is consistent with previous research that indicates the optimal frequency for identifying biological tissues using bioimpedance techniques is approximately 30 kHz. It is further found through animal cadaver studies that the complex impedance of the epidural space can not be discriminated from the adjacent tissues as with biological tissue studies. These findings are important and add to the body of knowledge on the subjects of needle guidance. The development of a tool that effectively directs a needle towards the epidural space has a crucial place in the medical industry. Despite the fact that the existing equipment can benefit from further investigation and modifications, these tools and the outcomes they produce have the potential to advance modern medicine.AFRIKAANS OPSOMMING: Die kompleksiteit van die uitvoering van ’n epidurale prosedure en die lokalisering van die epidurale spasie is welbekend aangesien dit vereis dat dokters staatmaak op hul kennis van menslike anatomie en ervaring om sukses te behaal. Hierdie benadering is dalk betroubaar, maar dit is subjektief. As gevolg hiervan word twee metodes ontwikkel en getoets om te help om ’n naald na die epidurale spasie te lei. Die ontwerp wat in hierdie dokument voorgestel word, identifiseer en ontwerp ’n stelsel wat in staat is om die epidurale spasie te identifiseer en aan te dui wanneer die naaldpunt kontak gemaak het met die epidurale spasie. Die resultate van die teoretiese ondersoekprosedures en voorlopige gesimuleerde studie verskaf die grondslag om volledig gemotiveerde besluite oor die finale eksperimentele toetsfase te lewer. Die identifisering van die naaldinvoegplek is die eerste stap om die naald na die epidurale spasie te lei. Naby-infrarooi (NIR) lig wat van ’n kort afstand deur optiese vesels oorgedra word, kan gebruik word om die epidurale spasie van buite die liggaam op te spoor. Die gesimuleerde resultate toon egter dat dit nie moontlik sal wees nie, aangesien die opsporingsreeks van die NIR-sensor minder is as die diepte van die epidurale spasie. Om te identifiseer wanneer die naald die epidurale ruimte binnegaan, word elektriese impedansie gemeet deur in-vitro-eksperimente met behulp van gelatienagtige fantome en varkmodelle. Die uitkomste van die eksperimentele studies is soortgelyk aan die wat deur die wiskundige simulasies verkry is. By 29,5 kHz word deur die biologiese weefselstudies ontdek dat die epidurale spasie maklik onderskei kan word van onderhuidse vet, spiere en ligamente. Beide die impedansiegrootte en die impedansiefasehoek toon dit. ’n Statisties beduidende verskil tussen die impedansie van die epidurale spasie en vet, spiere en ligament by 29.5 kHz word deur die data gedemonstreer (p < 0.05). Dit stem ooreen met vorige navorsing wat aandui dat die optimale frekwensie vir die identifisering van biologiese weefsels met behulp van bioimpedansietegnieke ongeveer 30 kHz is. Daar word verder gevind deur dierekadawerstudies dat die komplekse impedansie van die epidurale ruimte nie onderskei kan word van die aangrensende weefsels soos met biologiese weefselstudies nie. Hierdie bevindinge is belangrik en dra by tot die liggaam van kennis oor die onderwerpe van naaldleiding. Die ontwikkeling van ’n instrument wat ’n naald effektief na die epidurale spasie rig, het ’n deurslaggewende plek in die mediese industrie. Ten spyte van die feit dat die bestaande toerusting baat kan vind by verdere ondersoek en wysigings, het hierdie gereedskap en die uitkomste wat hulle lewer die potensiaal om moderne medisyne te bevorder.Master