Who will do general surgery?

The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.Advantages to patients of a single anaesthetic for more than one operation are obvious; attracting generalist surgeons, training them and ensuring they have adequate credentials remain hurdles.Martin H Bruening and Guy J Madder

Fine-scale Topoclimate Modeling and Climatic Treeline Prediction of Great Basin Bristlecone Pine (Pinus longaeva) in the American Southwest

Great Basin bristlecone pine (Pinus longaeva) and foxtail pine (Pinus balfouriana) are valuable paleoclimate resources due to the climatic sensitivity of their annually-resolved rings. Recent treeline research has shown that growing season temperatures limit tree growth at and just below the upper treeline. In the Great Basin, the presence of precisely dated remnant wood above modern treeline shows that this ecotone shifts at centennial timescales tracking long-term changes in climate; in some areas during the Holocene climatic optimum treeline was 100 meters higher than at present. Such phenomena has motivated this analysis; regional treeline position models built exclusively from climate data may identify characteristics specific to Great Basin treelines and inform future physiological studies, and provide a measure of climate sensitivity specific to bristlecone and foxtail pine treelines. This study implements a topoclimatic analysis—using topographic position to explain patterns in surface temperatures across complex mountainous terrain—to model treeline position of three semi-arid bristlecone and/or foxtail pine treelines in the Great Basin as a function of topographically modified climate variables calculated from in situ measurements. Results indicate: (1) the treelines used in this study require a growing season length of between 143 - 152 days and average temperature ranging from 5.5 - 7.6 °C, (2) site-specific treeline position models may be improved through topoclimatic analysis—specifically the inclusion of an integrated measure of climate rather than a growing season isotherm measured in degrees, (3) treeline position in the Great Basin is likely out of equilibrium with the current climate indicating a potential shift in the primary growth-limiting factor at the highest elevations where trees are found

Potent Attractant for Root-Knot Nematodes in Exudates from Seedling Root Tips of Two Host Species.

Root-knot nematodes (RKN; Meloidogyne spp.) can parasitize over 2,000 plant species and are generally considered to be the most agriculturally damaging group of plant-parasitic nematodes worldwide. Infective juveniles (J2) are non-feeding and must locate and invade a host before their reserves are depleted. However, what attracts J2 to appropriate root entry sites is not known. An aim of this research is to identify semiochemicals that attract RKN to roots. J2 of the three RKN species tested are highly attracted to root tips of both tomato and Medicago truncatula. For both hosts, mutants defective in ethylene signaling were found to be more attractive than those of wild type. We determined that cell-free exudates collected from tomato and M. truncatula seedling root tips were highly attractive to M. javanica J2. Using a pluronic gel-based microassay to monitor chemical fractionation, we determined that for both plant species the active component fractionated similarly and had a mass of ~400 based on size-exclusion chromatography. This characterization is a first step toward identification of a potent and specific attractant from host roots that attracts RKN. Such a compound is potentially a valuable tool for developing novel and safe control strategies

Catalytic hollow fiber membranes prepared using layer-by-layer adsorption of polyelectrolytes and metal nanoparticles

Immobilization of metalnanoparticles in hollowfibermembranes via alternating adsorption of polyelectrolytes and negatively charged Au nanoparticles yields catalytic reactors with high surface areas. SEM images show that this technique deposits a high density of unaggregated metalnanoparticles both on the surfaces and in the pores of the hollowfibers. Catalytic reduction of 4-nitrophenol with NaBH4, which can be easily monitored by UV–vis spectrophotometry, demonstrates that the nanoparticles in the hollowfibermembrane are highly catalytically active. In a single pass through the membrane, >99% of the 4-nitrophenol is reduced to 4-aminophenol, but this conversion decreases over time. The conversion decline may stem from catalyst fouling caused by by-products of 4-aminophenol oxidation

The multiplication of an influenza virus strain in a continuous line of mammalian cells

This article does not have an abstract

Ankle and midtarsal joint quasi-stiffness during walking with added mass

Examination of how the ankle and midtarsal joints modulate stiffness in response to increased force demand will aid understanding of overall limb function and inform the development of bio-inspired assistive and robotic devices. The purpose of this study is to identify how ankle and midtarsal joint quasi-stiffness are affected by added body mass during over-ground walking. Healthy participants walked barefoot over-ground at 1.25 m/s wearing a weighted vest with 0%, 15% and 30% additional body mass. The effect of added mass was investigated on ankle and midtarsal joint range of motion (ROM), peak moment and quasi-stiffness. Joint quasi-stiffness was broken into two phases, dorsiflexion (DF) and plantarflexion (PF), representing approximately linear regions of their moment-angle curve. Added mass significantly increased ankle joint quasi-stiffness in DF (p \u3c 0.001) and PF (p \u3c 0.001), as well as midtarsal joint quasi-stiffness in DF (p \u3c 0.006) and PF (p \u3c 0.001). Notably, the midtarsal joint quasi-stiffness during DF was ~2.5 times higher than that of the ankle joint. The increase in midtarsal quasi-stiffness when walking with added mass could not be explained by the windlass mechanism, as the ROM of the metatarsophalangeal joints was not correlated with midtarsal joint quasi-stiffness (r = −0.142, p = 0.540). The likely source for the quasi-stiffness modulation may be from active foot muscles, however, future research is needed to confirm which anatomical structures (passive or active) contribute to the overall joint quasi-stiffness across locomotor tasks

Linear effects in ATB movement

Munn (2001), Citko (2005), and others argue that in ATB movement initial and non-initial gaps exhibit asymmetries in reconstruction effects and weak crossover: only the initial ATB gap shows reconstruction and weak crossover. Munn argues that these asymmetries are due to the nature of the gap: the initial ATB gap is a real gap, while non-initial gaps are parasitic gaps. Parasitic gaps are generally claimed to show no reconstruction or weak crossover (e.g., Nissenbaum 2000). We re-examine reconstruction in ATB movement and parasitic gap constructions and show that in most cases the putative asymmetries between gaps are not real, and when there is an asymmetry it is due to linear order and not to the nature of the gap. We conclude that both ATB movement and parasitic gap constructions involve full copies in all gaps

Cluster Analysis and Topoclimate Modeling to Examine Bristlecone Pine Tree-ring Growth Signals in the Great Basin, USA

Tree rings have long been used to make inferences about the environmental factors that influence tree growth. Great Basin bristlecone pine is a long-lived species and valuable dendroclimatic resource, but often with mixed growth signals; in many cases, not all trees at one location are limited by the same environmental variable. Past work has identified an elevational threshold below the upper treeline above which trees are limited by temperature, and below which trees tend to be moisture limited. This study identifies a similar threshold in terms of temperature instead of elevation through fine-scale topoclimatic modeling, which uses a suite of topographic and temperature-sensor data to predict temperatures across landscapes. We sampled trees near the upper limit of growth at four high-elevation locations in the Great Basin region, USA, and used cluster analysis to find dual-signal patterns in radial growth. We observed dual-signal patterns in ring widths at two of those sites, with the signals mimicking temperature and precipitation patterns. Trees in temperature-sensitive clusters grew in colder areas, while moisture-sensitive cluster trees grew in warmer areas. We found thresholds between temperatureand moisture-sensitivity ranging from 7.4 °C to 8°C growing season mean temperature. Our findings allow for a better physiological understanding of bristlecone pine growth, and seek to improve the accuracy of climate reconstructions