The Thoracic Morphology of Archostemata and the Relationships of the Extant Suborders of Coleoptera (Hexapoda)

Thoracic structures of Tetraphalerus bruchi are described in detail. The results were compared with features found in other representatives of Archostemata and other coleopteran suborders. Differences between thoracic structures of Tetraphalerus and members of other archostematan subgroups are discussed. External and internal characters of larval and adult representatives of 37 genera of the coleopteran suborders are outlined, coded and analysed cladistically, with four groups of Neuropterida as outgroup taxa. The results strongly suggest the branching pattern Archostemata + [Adephaga + (Myxophaga + Polyphaga)]. Coleoptera excluding Archostemata are supported with a high Bremer support. Important evolutionary changes linked with this branching event are simplifications of the thoracic skeleton resulting in reduced degrees of freedom (i.e. a restricted movability, especially at the leg bases), and a distinct simplification of the muscle system. This development culminates in Polyphaga, which are also strongly supported as a clade. Internalization of the partly reduced propleura, further muscle losses, and the fusion of the mesoventrites and metaventrites—with reversal in Scirtoidea and Derodontidae—are autapomorphies of Polyphaga. Archostemata is a small relict group in contrast to highly successful xylobiontic groups of Polyphaga. The less efficient thoracic locomotor apparatus, the lack of cryptonephric Malpighian tubules, and the rise of angiosperms with beetle groups primarily adjusted to them may have contributed to the decline of Archostemata.Organismic and Evolutionary Biolog

Modeling four-dimensional metamaterials: A T-matrix approach to describe time-varying metasurfaces

Exploring the interaction of light with materials periodically structured in space and time is intellectually rewarding and, simultaneously, a computational challenge. Appropriate computational tools are urgently needed to explore how such upcoming photonic materials can control light on demand. Here, we introduce a semi-analytical approach based on the transition matrix (also known as T-matrix) to analyze the optical response of a spatiotemporal metasurface. The metasurface consists of a periodic arrangement of time-varying scattering particles. In our approach, we depart from an individual scatterer’s T-matrix to construct the effective T-matrix of the metasurface. From that effective T-matrix, all observable properties can reliably be predicted. We verify our semi-analytical approach with full-wave numerical simulations. We demonstrate a speed-up with our approach by a factor of more than 500 compared to a finite-element simulation. Finally, we exemplify our approach by studying the effect of time modulation on a Huygens’ metasurface and discuss some emerging observable features

Extensive collection of femtoliter pad secretion droplets in beetle Leptinotarsa decemlineata allows nanoliter microrheology

Pads of beetles are covered with long, deformable setae, each ending in a micrometric terminal plate coated with secretory fluid. It was recently shown that the layer of the pad secretion covering the terminal plates is responsible for the generation of strong attractive forces. However, less is known about the fluid itself because it is produced in extremely small quantity. We here present a first experimental investigation of the rheological properties of the pad secretion in the Colorado potato beetle {\it Leptinotarsa decemlineata}. Because the secretion is produced in an extremely small amount at the level of the terminal plate, we first develop a procedure based on capillary effects to collect the secretion. We then manage to incorporate micrometric beads, initially in the form of a dry powder, and record their thermal motion to determine the mechanical properties of the surrounding medium. We achieve such a quantitative measurement within the collected volume, much smaller than the $1 {\rm \mu}$l sample volume usually required for this technique. Surprisingly, the beetle secretion was found to behave as a purely viscous liquid, of high viscosity. This suggests that no specific complex fluid behaviour is needed during beetle locomotion. We build a scenario for the contact formation between the spatula at the setal tip and a substrate, during the insect walk. We show that the attachment dynamics of the insect pad computed from the high measured viscosity is in good agreement with observed insect pace. We finally discuss the consequences of the secretion viscosity on the insect adhesion

Preventing venous thromboembolism at a district hospital : a quality improvement study

CITATION: Beutel, B. G. & Jenkins, L. S.. 2015. Preventing venous thromboembolism at a district hospital : a quality improvement study. South African Family Practice, 57(2):64-68, doi:10.1080/20786190.2014.977033.The original publication is available at http://www.tandfonline.comBackground: Pulmonary embolism (PE) is the most common preventable cause of hospital deaths, and almost all hospitalised patients have at least one risk factor for venous thromboembolism (VTE). Despite the availability of highly effective thromboprophylaxis in preventing VTE, numerous studies worldwide have demonstrated its under-utilisation. The aim of this study was to review and improve the utilisation of thromboprophylaxis in the prevention of VTE in hospitalised patients at Oudtshoorn district hospital, and to make recommendations to the Western Cape Department of Health on how to improve the quality of care for patients at risk for VTE at district hospitals. Method: A quality improvement cycle (QIC). Retrospective analysis of files of adult patients admitted to the male and female wards at Oudtshoorn district hospital was performed prior to and after a five-month intervention phase. The target standards for the QIC were: (1) availability of a written hospital policy on VTE prevention; (2) every adult admission should have a formal VTE risk assessment documented; (3) every adult admission who is at risk for VTE should receive thromboprophylaxis. Results: Some 38% of adult patients admitted to Oudtshoorn Hospital, excluding the maternity ward, were at risk of developing VTE. There was no written hospital policy on VTE prevention. This was developed and made available during the intervention. In the pre-intervention group there were no patients who had a documented VTE risk assessment. The post intervention group showed a considerable increase with 45.2% having had a completed VTE risk assessment on admission (p < 0.001). In the pre-intervention group only 4.6% of patients who were at risk of VTE received thromboprophylaxis. There was a statistically significant difference in the number of patients at risk who received thromboprophylaxis in the post-intervention group where 36% of these patients received thromboprophylaxis (p < 0.001). Conclusions: The study identified a major shortcoming in the prevention of VTE in those patients at risk who were admitted to Oudtshoorn district hospital. An intervention as part of a quality improvement cycle has been able to demonstrate a significant improvement in the detection of patients who are at risk of VTE and a subsequent improvement in appropriate thromboprophylaxis. A number of barriers to their implementation have been identified and need to be addressed. This QIC may in time be of value to assist other district hospitals in addressing the issue of VTE prevention.http://www.tandfonline.com/doi/abs/10.1080/20786190.2014.977033Publisher's versio

Wonderfully weird: the head anatomy of the armadillo ant, Tatuidris tatusia (Hymenoptera: Formicidae: Agroecomyrmecinae), with evolutionary implications

Tatuidris tatusia Brown & Kempf, 1968, the armadillo ant, is a morphologically unique species found in low to high elevation forests in regions of Central and South America. It is one of only two extant representatives of the subfamily Agroecomyrmecinae, and very little is known about the biology of these ants, which are almost exclusively collected from leaf litter and have rarely been seen alive. Here, we illuminate the functional morphology and evolution of this species via detailed anatomical documentation of their exceptionally modified head. We describe and illustrate the skeletomuscular system, digestive tract, and cephalic glands based on high-resolution micro-computed tomography scan data. We hypothesize that the modifications which produce the unusual “shield-like” head shape are the result of complex optimizations for mandibular power, physical protection, and balance. The most conspicuous cephalic features are the broadening of the frontal region and foreshortening of the postgenal region. The former characteristic is likely also associated with the lateral position of the antennal scrobe, the inverted antennal articulation, and the broad attachment surface for the mandibular adductor muscles. This head geometry also comes with a degree of internal restructuring of the tentorium and the antennal musculature, which have a unique configuration among ants studied so far. The mandibular blades, and their articulations and muscles, are highly distinctive compared with previously evaluated species. Using a 3D-printed model, we were able to hypothesize their entire range of motion as the mandibles fit tightly into the oral foramen. Finally, we compare T. tatusia across other related subfamilies and discuss the evolution of the Agroecomyrmecinae and other species-poor and phylogenetically isolated “relictual” lineages.journal articl

HIV/AIDS risk perceptions and first sexual intercourse among youth in Cape Town, South Africa

HIV prevalence is high among South African youth. Health behavior models posit that perceived risk of HIV/AIDS is associated with HIV/AIDS risk behaviors, but research in sub-Saharan Africa that has considered the predictors of HIV/AIDS risk perceptions and behaviors or the relationship between them has been limited. Longitudinal data collected in 2002 and 2005 from 3,025 black, coloured, and white youth aged 14-22 (in 2002) in Cape Town, South Africa were analyzed using multivariate regression to examine correlates of perceived HIV/AIDS risk and one HIV/AIDS risk behavior, transition to first sex. Independent variables taken from the 2002 survey were used to predict dependent variables taken from the 2005 survey. Results indicate that most respondents viewed themselves at no risk or small risk of HIV infection. Perceived risk of HIV/AIDS was positively associated with having had sex and knowing somebody with HIV/AIDS. Among those who were virgins in 2002, perceived HIV/AIDS risk and knowing somebody with HIV/AIDS predicted entry into first sex by 2005 for females only. The effects of race on risk perceptions also varied by gender. In conclusion, HIV/AIDS education and prevention programs should consider more carefully how gender and race may intersect to influence risk perceptions and risk behaviors. The reciprocal relationship between risk perceptions and risk behaviors should also be considered in education and intervention programs