Anatomical and biomechanical traits of broiler chickens across ontogeny. Part II. Body segment inertial properties and muscle architecture of the pelvic limb

In broiler chickens, genetic success for desired production traits is often shadowed by welfare concerns related to musculoskeletal health. Whilst these concerns are clear, a viable solution is still elusive. Part of the solution lies in knowing how anatomical changes in afflicted body systems that occur across ontogeny influence standing and moving. Here, to demonstrate these changes we quantify the segment inertial properties of the whole body, trunk (legs removed) and the right pelvic limb segments of five broilers at three different age groups across development. We also consider how muscle architecture (mass, fascicle length and other properties related to mechanics) changes for selected muscles of the pelvic limb. All broilers used had no observed lameness, but we document the limb pathologies identified post mortem, since these two factors do not always correlate, as shown here. The most common leg disorders, including bacterial chondronecrosis with osteomyelitis and rotational and angular deformities of the lower limb, were observed in chickens at all developmental stages. Whole limb morphology is not uniform relative to body size, with broilers obtaining large thighs and feet between four and six weeks of age. This implies that the energetic cost of swinging the limbs is markedly increased across this growth period, perhaps contributing to reduced activity levels. Hindlimb bone length does not change during this period, which may be advantageous for increased stability despite the increased energetic costs. Increased pectoral muscle growth appears to move the centre of mass cranio-dorsally in the last two weeks of growth. This has direct consequences for locomotion (potentially greater limb muscle stresses during standing and moving). Our study is the first to measure these changes in the musculoskeletal system across growth in chickens, and reveals how artificially selected changes of the morphology of the pectoral apparatus may cause deficits in locomotion

Electronic structure and total energy of interstitial hydrogen in iron: Tight binding models

An application of the tight binding approximation is presented for the description of electronic structure and interatomic force in magnetic iron, both pure and containing hydrogen impurities. We assess the simple canonical d-band description in comparison to a non orthogonal model including s and d bands. The transferability of our models is tested against known properties including the segregation energies of hydrogen to vacancies and to surfaces of iron. In many cases agreement is remarkably good, opening up the way to quantum mechanical atomistic simulation of the effects of hydrogen on mechanical properties

So near and yet so far: Harmonic radar reveals reduced homing ability of nosema infected honeybees

Pathogens may gain a fitness advantage through manipulation of the behaviour of their hosts. Likewise, host behavioural changes can be a defence mechanism, counteracting the impact of pathogens on host fitness. We apply harmonic radar technology to characterize the impact of an emerging pathogen - Nosema ceranae (Microsporidia) - on honeybee (Apis mellifera) flight and orientation performance in the field. Honeybees are the most important commercial pollinators. Emerging diseases have been proposed to play a prominent role in colony decline, partly through sub-lethal behavioural manipulation of their hosts. We found that homing success was significantly reduced in diseased (65.8%) versus healthy foragers (92.5%). Although lost bees had significantly reduced continuous flight times and prolonged resting times, other flight characteristics and navigational abilities showed no significant difference between infected and non-infected bees. Our results suggest that infected bees express normal flight characteristics but are constrained in their homing ability, potentially compromising the colony by reducing its resource inputs, but also counteracting the intra-colony spread of infection. We provide the first high-resolution analysis of sub-lethal effects of an emerging disease on insect flight behaviour. The potential causes and the implications for both host and parasite are discussed

So near and yet so far: Harmonic radar reveals reduced homing ability of nosema infected honeybees

Pathogens may gain a fitness advantage through manipulation of the behaviour of their hosts. Likewise, host behavioural changes can be a defence mechanism, counteracting the impact of pathogens on host fitness. We apply harmonic radar technology to characterize the impact of an emerging pathogen - Nosema ceranae (Microsporidia) - on honeybee (Apis mellifera) flight and orientation performance in the field. Honeybees are the most important commercial pollinators. Emerging diseases have been proposed to play a prominent role in colony decline, partly through sub-lethal behavioural manipulation of their hosts. We found that homing success was significantly reduced in diseased (65.8%) versus healthy foragers (92.5%). Although lost bees had significantly reduced continuous flight times and prolonged resting times, other flight characteristics and navigational abilities showed no significant difference between infected and non-infected bees. Our results suggest that infected bees express normal flight characteristics but are constrained in their homing ability, potentially compromising the colony by reducing its resource inputs, but also counteracting the intra-colony spread of infection. We provide the first high-resolution analysis of sub-lethal effects of an emerging disease on insect flight behaviour. The potential causes and the implications for both host and parasite are discussed

The influence of hydrogen on plasticity in pure iron—theory and experiment

Tensile stress relaxation is combined with transmission electron microscopy to reveal dramatic changes in dislocation structure and sub structure in pure α-Fe as a result of the effects of dissolved hydrogen. We find that hydrogen charged specimens after plastic deformation display a very characteristic pattern of trailing dipoles and prismatic loops which are absent in uncharged pure metal. We explain these observations by use of a new self consistent kinetic Monte Carlo model, which in fact was initially used to predict the now observed microstructure. The results of this combined theory and experimental study is to shed light on the fundamental mechanism of hydrogen enhanced localised plasticity

Asteroseismic classification of stellar populations among 13000 red giants observed by Kepler

Of the more than 150000 targets followed by the Kepler Mission, about 10% were selected as red giants. Due to their high scientific value, in particular for Galaxy population studies and stellar structure and evolution, their Kepler light curves were made public in late 2011. More than 13000 (over 85%) of these stars show intrinsic flux variability caused by solar-like oscillations making them ideal for large scale asteroseismic investigations. We automatically extracted individual frequencies and measured the period spacings of the dipole modes in nearly every red giant. These measurements naturally classify the stars into various populations, such as the red giant branch, the low-mass (M/Msol 1.8) secondary clump. The period spacings also reveal that a large fraction of the stars show rotationally induced frequency splittings. This sample of stars will undoubtedly provide an extremely valuable source for studying the stellar population in the direction of the Kepler field, in particular when combined with complementary spectroscopic surveys.Comment: 6 page, 5 figures, accepted by ApJ

It's EZ to Evolve ZAMS Stars: A Program Derived from Eggleton's Stellar Evolution Code

"Evolve ZAMS", "EZ" for short, is derived from Peter Eggleton's stellar evolution program. The core of EZ is a stripped down, rewritten version of a subset of Eggleton's code, specialized to handle single star evolution from the zero-age main sequence until forced to stop by an event such as a helium flash or a crystallizing core. The procedure and data interfaces to the program are designed to be easy to use while still providing a wide range of function. EZ is written in Fortran 95 following current programming practices and can be downloaded from http://theory.kitp.ucsb.edu/~paxton/.Comment: 2 pages. To appear in PASP. Download tar file with source code, data, and instructions for building EZ from http://theory.kitp.ucsb.edu/~paxton/ -- website has more information and pdf's for many plots of stellar evolutio

Text messaging is a useful reminder tool

Introduction Longitudinal studies of adolescents must be ‘adolescent-friendly’, to collect data and to encourage maintenance in the study cohort. Text messaging may offer a feasible means to do both. Methods Adolescents in the Adolescent Rural Cohort, Hormones and Health, Education, Environments and Relationships (ARCHER) study (n=342) are sent automated text messages every 3 months, prompting biological specimen collection. Results A total of 99.2% of participants (or their parents) owned a mobile phone, of which 89.1% of participants responded to text messages and 97.3% of intended urine samples were collected. The average time to provide a urine sample after prompting correlated with time to reply to Short Message Service (SMS). Conclusions This study shows SMS can be used effectively in longitudinal research involving adolescents and is feasible and useful as a reminder tool for regular biological specimen collection.Australian National Health and Medical Research Counci

Engineering three-dimensional bone macro-tissues by guided fusion of cell spheroids

Introduction: Bioassembly techniques for the application of scaffold-freetissue engineering approaches have evolved in recent years towardproducing larger tissue equivalents that structurally and functionally mimicnative tissues. This study aims to upscale a 3-dimensional bone in-vitromodel through bioassembly of differentiated rat osteoblast (dROb) spheroidswith the potential to develop and mature into a bone macrotissue.Methods: dROb spheroids in control and mineralization media at differentseeding densities (1 × 104, 5 × 104, and 1 × 105 cells) were assessed for cellproliferation and viability by trypan blue staining, for necrotic core byhematoxylin and eosin staining, and for extracellular calcium by Alizarin redand Von Kossa staining. Then, a novel approach was developed tobioassemble dROb spheroids in pillar array supports using a customizedbioassembly system. Pillar array supports were custom-designed and printedusing Formlabs Clear Resin® by Formlabs Form2 printer. These supports wereused as temporary frameworks for spheroid bioassembly until fusionoccurred. Supports were then removed to allow scaffold-free growth andmaturation of fused spheroids. Morphological and molecular analyses wereperformed to understand their structural and functional aspects.Results: Spheroids of all seeding densities proliferated till day 14, andmineralization began with the cessation of proliferation. Necrotic core sizeincreased over time with increased spheroid size. After the bioassembly ofspheroids, the morphological assessment revealed the fusion of spheroidsover time into a single macrotissue of more than 2.5 mm in size with mineralformation. Molecular assessment at different time points revealed osteogenicmaturation based on the presence of osteocalcin, downregulation of Runx2(p < 0.001), and upregulated alkaline phosphatase (p < 0.01).Discussion: With the novel bioassembly approach used here, 3D bonemacrotissues were successfully fabricated which mimicked physiological osteogenesis both morphologically and molecularly. This biofabricationapproach has potential applications in bone tissue engineering,contributing to research related to osteoporosis and other recurrentbone ailments