Digital X-rays come of age

In early November 1895 Willem Röntgen performed an experiment in which invisible cathode rays, generated by electrostatic discharges from within an evacuated glass tube, caused a cardboard screen painted with barium platinocyanide to fluoresce. Although the new rays would also come to bear his name, Röntgen called them X-rays, apparently using the mathematical designation for something unknown.1 While investigating the ability of various materials to stop the Xrays, he stepped into the line of the rays to introduce a piece of lead and was startled to see an image of his own skeleton shimmering on the fluorescent screen. His groundbreaking article2 was published less than 2 months later on 28 December 1895

Re-interpreting the evidence for bipedality in Homo floresiensis

The unveiling in October 2004 of the remains of a pygmy-sized hominin recovered from a cave on the island of Flores, Indonesia, sparked an intense series of debates within the palaeoanthropology community. The discoverers diagnosed it to be a new species of Homo, which they called Homo floresiensis, and they interpreted the postcranial morphology as being 'consistent with human-like obligate bipedalism'. We have examined the morphology with the aim of determining whether biomechanical evidence supports the claim that this hominin - known as LB1 - was indeed habitually bipedal. LB1's innominate bone differs from that of modern humans through the marked lateral flaring of the ilium, while her femur has a small head and a relatively long neck. Although these features are also found in australopithecines and are commonly regarded as 'primitive' traits, we concluded that none would have prevented her from exhibiting an efficient, bipedal gait. Having established that LB1 walked on two legs, we employed the principle of dynamic similarity to speculate how she might have walked. Assuming the gait of LB1 was dynamically similar to that of modern Homo sapiens, we used known dimensionless parameters, together with her leg length (0.55 m), to estimate her fundamental gait parameters : step length = 0.45 m, step frequency = 2.48 steps / second and speed = 1.11 m/s. Our review has provided insights regarding the way in which LB1 and her fellow diminutive hominins walked about the island of Flores over 18 000 years ago

Alternatives to the publication subsidy for research funding

Government policy on research funding has a direct impact on the behaviour of academics, so we need to ask what sort of behaviour should be encouraged in South Africa. Instead of an emphasis on the number of publications, our focus should rather be on a subsidy system that inspires our institutions to aim for a level of scholarship that is able to withstand the scrutiny of an international audience. Perhaps now is the time to grasp the nettle and to consider using the National Research Foundation's rating system instead of the publication count

A commentary on the intellectual health of the nation

The record of high-quality research at South African universities is not as impressive as we may have thought, according to some international rankings. Whatever we might think of these assessments, we have to take them seriously. We suggest ways in which our universities and other institutions of higher learning might raise the level of their game

Diagnosing breast cancer: an opportunity for innovative engineering

Background. In an ancient papyrus, dating back to 2500 BC, an Egyptian named Imhotep, thought to be the first physician and engineer in history, offers a glimpse into the earliest recorded case of breast cancer. Treatment has evolved over the years, from radical mastectomy to radiation by X-rays, and from adjuvant chemotherapy to hormonal therapy. A key challenge in fighting the ‘war’ on breast cancer is early diagnosis and here innovative engineers play a vital role. Aims. While full-field digital mammography has emerged in the past decade, this technique suffers from relatively high dose levels and poor sensitivity when the breasts are dense. We aimed to develop a diagnostic imaging system that exposes the patient to lower ionising radiation and improves the sensitivity and specificity for women with dense breasts. Results. Our PantoScanner platform has been designed to implement slot scanning digital X-rays, thereby lowering the dose and increasing signal-to-noise ratio, while also accommodating automated ultrasound and digital tomosynthesis. Early results based on mammographic phantoms are encouraging while the PantoScanner is undergoing clinical testing prior to commercial release. Conclusion. Since breast cancer kills 500 000 people globally every year, early diagnosis by breast screening could save the lives of many women. Our fervent hope is that the PantoScanner system will significantly contribute to this effort in South Africa and around the world

Auxin and tryptophan homeostasis are facilitated by the ISS1/VAS1 aromatic aminotransferase in arabidopsis

Indole-3-acetic acid (IAA) plays a critical role in regulating numerous aspects of plant growth and development. While there is much genetic support for tryptophan-dependent (Trp-D) IAA synthesis pathways, there is little genetic evidence for tryptophan-independent (Trp-I) IAA synthesis pathways. Using Arabidopsis, we identified two mutant alleles of ISS1 ( I: ndole S: evere S: ensitive) that display indole-dependent IAA overproduction phenotypes including leaf epinasty and adventitious rooting. Stable isotope labeling showed that iss1, but not WT, uses primarily Trp-I IAA synthesis when grown on indole-supplemented medium. In contrast, both iss1 and WT use primarily Trp-D IAA synthesis when grown on unsupplemented medium. iss1 seedlings produce 8-fold higher levels of IAA when grown on indole and surprisingly have a 174-fold increase in Trp. These findings indicate that the iss1 mutant's increase in Trp-I IAA synthesis is due to a loss of Trp catabolism. ISS1 was identified as At1g80360, a predicted aromatic aminotransferase, and in vitro and in vivo analysis confirmed this activity. At1g80360 was previously shown to primarily carry out the conversion of indole-3-pyruvic acid to Trp as an IAA homeostatic mechanism in young seedlings. Our results suggest that in addition to this activity, in more mature plants ISS1 has a role in Trp catabolism and possibly in the metabolism of other aromatic amino acids. We postulate that this loss of Trp catabolism impacts the use of Trp-D and/or Trp-I IAA synthesis pathways.T32 AR059033 - NIAMS NIH HH

The Stability of Retrospective Pre-injury Symptom Ratings Following Pediatric Concussion.

Objective: To determine the stability of children\u27s retrospective ratings of pre-injury levels of symptoms over time following concussion. Methods: Children and adolescents (n = 3,063) between the ages of 5–17 diagnosed with a concussion by their treating pediatric emergency department (PED) physician within 48 h of injury completed the Post-Concussion Symptom Inventory (PCSI) at the PED and at 1, 2, 4, 8, and 12-weeks post-injury. At each time point, participants retrospectively recalled their pre-injury levels of post-injury symptoms. The PCSI has three age-appropriate versions for children aged 5–7 (PCSI-SR5), 8–12 (PCSI-SR8), and 13–18 (PCSI-SR13). Total scale, subscales (physical, cognitive, emotional, and sleep), and individual items from the PCSI were analyzed for stability using Gini\u27s mean difference (GMD). Results: The mean GMD for total score was 0.31 (95% CI = 0.28, 0.34) for the PCSI-SR5, 0.19 (95% CI = 0.18, 0.20) for the PCSI-SR8, and 0.17 (95% CI = 0.16, 0.18) for the PCSI-SR13. Subscales ranged from mean GMD 0.18 (physical) to 0.31 (emotional) for the PCSI-SR8 and 0.16 (physical) to 0.31 (fatigue) for the PCSI-SR13. At the item-level, mean GMD ranged from 0.13 to 0.60 on the PCSI-SR5, 0.08 to 0.59 on the PCSI-SR8, and 0.11 to 0.41 on the PCSI-SR13. Conclusions: Children and adolescents recall their retrospective pre-injury symptom ratings with good-to-perfect stability over the first 3-months following their concussion. Although some individual items underperformed, variability was reduced as items were combined at the subscale and full-scale level. There is limited benefit gained from collecting multiple pre-injury symptom queries

Towards More Precise Survey Photometry for PanSTARRS and LSST: Measuring Directly the Optical Transmission Spectrum of the Atmosphere

Motivated by the recognition that variation in the optical transmission of the atmosphere is probably the main limitation to the precision of ground-based CCD measurements of celestial fluxes, we review the physical processes that attenuate the passage of light through the Earth's atmosphere. The next generation of astronomical surveys, such as PanSTARRS and LSST, will greatly benefit from dedicated apparatus to obtain atmospheric transmission data that can be associated with each survey image. We review and compare various approaches to this measurement problem, including photometry, spectroscopy, and LIDAR. In conjunction with careful measurements of instrumental throughput, atmospheric transmission measurements should allow next-generation imaging surveys to produce photometry of unprecedented precision. Our primary concerns are the real-time determination of aerosol scattering and absorption by water along the line of sight, both of which can vary over the course of a night's observations.Comment: 41 pages, 14 figures. Accepted PAS

Linking microbial community structure and function during the acidified anaerobic digestion of grass

This research was funded by the Irish Higher Education Authority Program for Research in Third Level Institutions Cycle 5: – PRTLI-5 ESI Ph.D. ENS Program. This work was also supported by the Wellcome Trust (grant number 094476/Z/10/Z for the TripleTOF 5600 mass spectrometer at the University of St Andrews), NERC (grant number NE/L011956/1), and a Royal Irish Academy Mobility Grant.Harvesting valuable bioproducts from various renewable feedstocks is necessary for the critical development of a sustainable bioeconomy. Anaerobic digestion is a well-established technology for the conversion of wastewater and solid feedstocks to energy with the additional potential for production of process intermediates of high market values (e.g. carboxylates). In recent years, first-generation biofuels typically derived from food crops have been widely utilised as a renewable source of energy. The environmental and socioeconomic limitations of such strategy, however, have led to the development of second-generation biofuels utilising, amongst other feedstocks, lignocellulosic biomass. In this context, the anaerobic digestion of perennial grass holds great promise for the conversion of sustainable renewable feedstock to energy and other process intermediates. The advancement of this technology however, and its implementation for industrial applications, relies on a greater understanding of the microbiome underpinning the process. To this end, microbial communities recovered from replicated anaerobic bioreactors digesting grass were analysed. The bioreactors leachates were not buffered and acidic pH (between 5.5 and 6.3) prevailed at the time of sampling as a result of microbial activities. Community composition and transcriptionally active taxa were examined using 16S rRNA sequencing and microbial functions were investigated using metaproteomics. Bioreactor fraction, i.e. grass or leachate, was found to be the main discriminator of community analysis across the three molecular level of investigation (DNA, RNA and proteins). Six taxa, namely Bacteroidia, Betaproteobacteria, Clostridia, Gammaproteobacteria, Methanomicrobia and Negativicutes accounted for the large majority of the three datasets. The initial stages of grass hydrolysis were carried out by Bacteroidia, Gammaproteobacteria and Negativicutes in the grass biofilms, in addition to Clostridia in the bioreactor leachates. Numerous glycolytic enzymes and carbohydrate transporters were detected throughout the bioreactors in addition to proteins involved in butanol and lactate production. Finally, evidence of the prevalence of stressful conditions within the bioreactors and particularly impacting Clostridia was observed in the metaproteomes. Taken together, this study highlights the functional importance of Clostridia during the anaerobic digestion of grass and thus research avenues allowing members of this taxon to thrive should be explored.Publisher PDFPeer reviewe

Mammals of the La Selva–Braulio Carrillo Complex, Costa Rica.

Resumen—El complejo La Selva-Braulio Carrillo de Costa Rica abarca un pasillo protejido de 60 kilómetros de bosque pluvial y selva nublada del Caribe. Extendiéndose desde 30 metros sobre el nivel del mar, en la Estación Biológica de La Selva, hasta 2,906 metros, en la cima del Volcán Barva. El compiejo de 52,000 hectáreas cubre cuatro zonas de vida y dos zonas de transición, incluyendo bosque húmedo tropical, bosque húmedo tropical con transición fría, bosque pluvial tropical pre-montano con transición húmeda, bosque pluvial pre-montano tropical, bosque pluvial montano-bajo, y bosque pluvial montano. Localizada en la parte noreste del país, el área es representativo de los bosques con pendiente de America Central y el Caribe que se extienden desde México hasta Panamá. La extensa gradientede este complejo brinda lugares protejidos para una variedad de migrantes altitudinales. Con el apoyo del National Geographic Society y Rice Foundation, la Organización de Estudios Tropicales organizó un estudio biológico del complejo a principios de 1986. El equipo trabajó en seis puntos de interés a lo largo del corte transversal de elevación establecido por la expedición: 300 m, 700 m, 1,000 m, 1,500 m, 2,050 m, y 2,600 m. Nosotros suplementamos nuestros archivos de colección con archivos inéditos puestos a la disposición por colegas, archivos en la literatura publicada, y especímenes en colecciones de museos. Además, se resumen las observaciones anotadas por una variedad de observadores en la Estación Biológica de La Selva. La fauna mamífera del complejo consiste de 143 especies incluyendo 79 murciélagos, 23 roedores, 16 carnívoros, 7 marsupiales, 6 edentatas, 4 artiodáctilos, 3 monos, 2 conejos, 2 musarañas, y 1 perisodáctilo. Es probable que por lo menos diez especies adicionales se encuentra allí. El único mamífero que probablemente fue extirpado de este área es el oso caballo. Reconociendo la importancia del área para animales y el género humano en general, el gobierno de Costa Rica añadió 13,500 hectáreas al complejo el 13 de Abril de 1986. Este área, previamente conocido como la "Zona Protectora," suministró el eslabón de la elevación media entre la tierra baja de la Estación Biológica de La Selva y el bosque Montano del Parque Nacional Braulio Carrillo. Desafortunadamente, la destrucción del bosque húmedo que circunda el complejo pronto se transformará en una isla aislada de bosque protejido. Así, el área se volverá cada vez más valiosa como refugio para muchas especies que necesitan espacios grandes en que el habitat no ha sido perturbado.Costa Rica's La Selva-Braulio Carrillo complex encompasses a 60-km protected corridor of Caribbean rain and cloud forest extending from 30 m at the La Selva Biological Station to 2,906 m at the top of Volcán Barva. The 52,000-ha complex covers four life zones and two transitional zones, including tropical wet forest, tropical wet forest cool-transition, tropical premontane wet-transition rain forest, tropical premontane rain forest, lower montane rain forest, and montane rain forest. Located in the northeastern part of the country, the area is representative of Central American Caribbean slope forests that extend from Mexico to Panama. The extensive elevational gradient of the complex provides protected habitat for a variety of altitudinal migrants. With support from the National Geographic Society and Rice Foundation, the Organization for Tropical Studies organized a biological survey of the complex in early 1986. The mammal team worked at six sites along the elevational transect established by the expedition: 300 m, 700 m, 1,000 m, 1,500 m, 2,050 m, and 2,600 m. We supplemented our collecting records with unpublished records made available by colleagues, records in the published literature, and specimens in museum collections. In addition, observations recorded by a variety of observers at the La Selva Biological Station are summarized. The mammal fauna of the complex comprises 143 species including 79 bats, 23 rodents, 16 carnivores, 7 marsupials, 6 edentates, 4 artiodactyls, 3 primates, 2 rabbits, 2 shrews, and 1 perissodactyl. At least 10 additional species are likely to occur there. The only species of mammal likely to have been extirpated from the area is the giant anteater. Recognizing the importance of the area to wildlife and to mankind in general, the government of Costa Rica added 13,500 ha to the complex on 13 April 1986. This area, previously known as the "Zona Protectora," provided the mid-elevational link between the lowlands of the La Selva Biological Station and the montane forests of Braulio Carrillo National Park. Unfortunately, destruction of the rain forests surrounding the complex will soon render it an isolated island of protected forest. Thus, the area will become increasingly valuable as a refuge for many species with home ranges that require extensive tracts of undisturbed habitat