Behavioural syndromes in brook charr, Salvelinus fontinalis: prey-search in the field corresponds with space use in novel laboratory situations

Recently emerged brook charr foraging in still-water pools along the sides of streams tend to be either sedentary, feeding from the lower portion of the water column (a sit-and-wait tactic) near the stream bank, or very active, feeding from the upper portion of the water column (an active search tactic) away from the bank. We tested whether the search tactics used by charr in the field represent behavioural syndromes related to activity and space use. After quantifying the behaviour of fish in the field, focal individuals were captured and their behaviour quantified in novel environment experiments in the laboratory. In an aquarium, individuals that used an active search tactic in the field spent a higher proportion of time moving, spent less time near the aquarium bottom, and took less time to find their way out of an erect glass jar, on average, than did individuals that used a sit-and-wait tactic in the field. When presented with near-bank and open-water conditions over 6 days in the laboratory, individuals that used an active search tactic in the field remained active and altered their activity less, on average, than individuals that used a sit-and-wait tactic in the field. Immediate responses to a pebble dropped in the aquarium (simulated risk from above) were not correlated with field behaviour. The search tactics used by brook charr in the field reflect part of a behavioural syndrome related to general activity and space use, but not to startle responses. These initial, individual differences in behaviour provide important raw material for the initial stages of resource polymorphism. © 2007 The Association for the Study of Animal Behaviour

Maternal Smoke Exposure Impairs the Long-Term Fertility of Female Offspring in a Murine Model.

The theory of fetal origins of adult disease was first proposed in 1989, and in the decades since, a wide range of other diseases from obesity to asthma have been found to originate in early development. Because mammalian oocyte development begins in fetal life it has been suggested that environmental and lifestyle factors of the mother could directly impact the fertility of subsequent generations. Cigarette smoke is a known ovotoxicant in active smokers, yet disturbingly 13% of Australian and 12% of US women continue to smoke throughout pregnancy. The focus of our investigation was to characterize the adverse effects of smoking on ovary and oocyte quality in female offspring exposed in utero. Pregnant mice were nasally exposed to cigarette smoke for 12 wk throughout pregnancy/lactation, and ovary and oocyte quality of the F1 (maternal smoke exposed) generation was examined. Neonatal ovaries displayed abnormal somatic cell proliferation and increased apoptosis, leading to a reduction in follicle numbers. Further investigation found that altered somatic cell proliferation and reduced follicle number continued into adulthood; however, apoptosis did not. This reduction in follicles resulted in decreased oocyte numbers, with these oocytes found to have elevated levels of oxidative stress, altered metaphase II spindle, and reduced sperm-egg interaction. These ovarian and oocyte changes ultimately lead to subfertility, with maternal smoke-exposed animals having smaller litters and also taking longer to conceive. In conclusion, our results demonstrate that in utero and lactational exposure to cigarette smoke can have long-lasting effects on the fertility of the next generation of females

Bioavailability in soils

The consumption of locally-produced vegetables by humans may be an important exposure pathway for soil contaminants in many urban settings and for agricultural land use. Hence, prediction of metal and metalloid uptake by vegetables from contaminated soils is an important part of the Human Health Risk Assessment procedure. The behaviour of metals (cadmium, chromium, cobalt, copper, mercury, molybdenum, nickel, lead and zinc) and metalloids (arsenic, boron and selenium) in contaminated soils depends to a large extent on the intrinsic charge, valence and speciation of the contaminant ion, and soil properties such as pH, redox status and contents of clay and/or organic matter. However, chemistry and behaviour of the contaminant in soil alone cannot predict soil-to-plant transfer. Root uptake, root selectivity, ion interactions, rhizosphere processes, leaf uptake from the atmosphere, and plant partitioning are important processes that ultimately govern the accumulation ofmetals and metalloids in edible vegetable tissues. Mechanistic models to accurately describe all these processes have not yet been developed, let alone validated under field conditions. Hence, to estimate risks by vegetable consumption, empirical models have been used to correlate concentrations of metals and metalloids in contaminated soils, soil physico-chemical characteristics, and concentrations of elements in vegetable tissues. These models should only be used within the bounds of their calibration, and often need to be re-calibrated or validated using local soil and environmental conditions on a regional or site-specific basis.Mike J. McLaughlin, Erik Smolders, Fien Degryse, and Rene Rietr

Initial management of potential occult scaphoid fracture in Australasia

AIM: To characterise current management of adult patients with possible occult scaphoid fracture in Australasian emergency departments. METHODS: Internet-based survey of Directors of Emergency Medicine Training throughout Australasia. Data collected included the most common management used in ED for patients with possible occult scaphoid fracture and whether there was a guideline regarding management of such cases. Data are reported as descriptive statistics. RESULTS: 61 responses were received (response rate 73%). The most common management reported was immobilisation in a backslab (23, 38%) or full cast (19, 32%) with clinical assessment and re-X-ray in 7-10 days. CT scan within 7 days was used by 9 (15%), bone scan within 7 days by 6 (10%) and MRI within 7 days by 3 (5%). Very few sites were using same day/next day CT or MRI. Eighty-three percent of sites reported not having a guideline/protocol for this condition. CONCLUSION: The traditional approach to management of possible occult scaphoid fracture of immobilisation with re-X-ray at 7-10 days remains the most commonly used in Australasia, despite evidence that this is probably over-treatment with significant consequences for patients. The place of advanced imaging for investigation of potential scaphoid fractures requires further research

A new concept for the combination of optical interferometers and high-resolution spectrographs

The combination of high spatial and spectral resolution in optical astronomy enables new observational approaches to many open problems in stellar and circumstellar astrophysics. However, constructing a high-resolution spectrograph for an interferometer is a costly and time-intensive undertaking. Our aim is to show that, by coupling existing high-resolution spectrographs to existing interferometers, one could observe in the domain of high spectral and spatial resolution, and avoid the construction of a new complex and expensive instrument. We investigate in this article the different challenges which arise from combining an interferometer with a high-resolution spectrograph. The requirements for the different sub-systems are determined, with special attention given to the problems of fringe tracking and dispersion. A concept study for the combination of the VLTI (Very Large Telescope Interferometer) with UVES (UV-Visual Echelle Spectrograph) is carried out, and several other specific instrument pairings are discussed. We show that the proposed combination of an interferometer with a high-resolution spectrograph is indeed feasible with current technology, for a fraction of the cost of building a whole new spectrograph. The impact on the existing instruments and their ongoing programs would be minimal.Comment: 27 pages, 9 figures, Experimental Astronomy; v2: accepted versio

X-ray emission from isolated neutron stars

X-ray emission is a common feature of all varieties of isolated neutron stars (INS) and, thanks to the advent of sensitive instruments with good spectroscopic, timing, and imaging capabilities, X-ray observations have become an essential tool in the study of these objects. Non-thermal X-rays from young, energetic radio pulsars have been detected since the beginning of X-ray astronomy, and the long-sought thermal emission from cooling neutron star's surfaces can now be studied in detail in many pulsars spanning different ages, magnetic fields, and, possibly, surface compositions. In addition, other different manifestations of INS have been discovered with X-ray observations. These new classes of high-energy sources, comprising the nearby X-ray Dim Isolated Neutron Stars, the Central Compact Objects in supernova remnants, the Anomalous X-ray Pulsars, and the Soft Gamma-ray Repeaters, now add up to several tens of confirmed members, plus many candidates, and allow us to study a variety of phenomena unobservable in "standard'' radio pulsars.Comment: Chapter to be published in the book of proceedings of the 1st Sant Cugat Forum on Astrophysics, "ICREA Workshop on the high-energy emission from pulsars and their systems", held in April, 201

Nel positively regulates the genesis of retinal ganglion cells by promoting their differentiation and survival during development

Peer reviewedPublisher PD

Mechanical Systems with Symmetry, Variational Principles, and Integration Algorithms

This paper studies variational principles for mechanical systems with symmetry and their applications to integration algorithms. We recall some general features of how to reduce variational principles in the presence of a symmetry group along with general features of integration algorithms for mechanical systems. Then we describe some integration algorithms based directly on variational principles using a discretization technique of Veselov. The general idea for these variational integrators is to directly discretize Hamilton’s principle rather than the equations of motion in a way that preserves the original systems invariants, notably the symplectic form and, via a discrete version of Noether’s theorem, the momentum map. The resulting mechanical integrators are second-order accurate, implicit, symplectic-momentum algorithms. We apply these integrators to the rigid body and the double spherical pendulum to show that the techniques are competitive with existing integrators

Inflammatory cytokines and biofilm production sustain Staphylococcus aureus outgrowth and persistence: A pivotal interplay in the pathogenesis of Atopic Dermatitis

Individuals with Atopic dermatitis (AD) are highly susceptible to Staphylococcus aureus colonization. However, the mechanisms driving this process as well as the impact of S. aureus in AD pathogenesis are still incompletely understood. In this study, we analysed the role of biofilm in sustaining S. aureus chronic persistence and its impact on AD severity. Further we explored whether key inflammatory cytokines overexpressed in AD might provide a selective advantage to S. aureus. Results show that the strength of biofilm production by S. aureus correlated with the severity of the skin lesion, being significantly higher (P < 0.01) in patients with a more severe form of the disease as compared to those individuals with mild AD. Additionally, interleukin (IL)-β and interferon γ (IFN-γ), but not interleukin (IL)-6, induced a concentration-dependent increase of S. aureus growth. This effect was not observed with coagulase-negative staphylococci isolated from the skin of AD patients. These findings indicate that inflammatory cytokines such as IL1-β and IFN-γ, can selectively promote S. aureus outgrowth, thus subverting the composition of the healthy skin microbiome. Moreover, biofilm production by S. aureus plays a relevant role in further supporting chronic colonization and disease severity, while providing an increased tolerance to antimicrobials

Cost effectiveness of first-line oral therapies for pulmonary arterial hypertension: A modelling study

Background: In recent years, a significant number of costly oral therapies have become available for the treatment of pulmonary arterial hypertension (PAH). Funding decisions for these therapies requires weighing up their effectiveness and costs. Objective: The aim of this study was to assess the cost effectiveness of monotherapy with oral PAH-specific therapies versus supportive care as initial therapy for patients with functional class (FC) II and III PAH in Canada. Methods: A cost-utility analysis, from the perspective of a healthcare system and based on a Markov model, was designed to estimate the costs and quality-adjusted life-years (QALYs) associated with bosentan, ambrisentan, riociguat, tadalafil, sildenafil and supportive care for PAH in treatment-naïve patients. Separate analyses were conducted for cohorts of patients commencing therapy at FC II and III PAH. Transition probabilities, based on the relative risk of improving and worsening in FC with treatment versus placebo, were derived from a recent network meta-analysis. Utility values and costs were obtained from published data and clinical expert opinion. Extensive sensitivity analyses were conducted. Results: Analysis suggests that sildenafil is the most cost-effective therapy for PAH in patients with FC II or III. Sildenafil was both the least costly and most effective therapy, thereby dominating all other treatments. Tadalafil was also less costly and more effective than supportive care in FC II and III; however, sildenafil was dominant over tadalafil. Even given the uncertainty within the clinical inputs, the probabilistic sensitivity analysis showed that apart from sildenafil and tadalafil, the other PAH therapies had negligible probability of being the most cost effective. Conclusion: The results show that initiation of therapy with sildenafil is likely the most cost-effective strategy in PAH patients with either FC II or III disease.This research was supported by funds from the Canadian Agency for Drugs and Technologies in Health (CADTH)