Giant central lumbar disc herniations: a case for the transdural approach.

Giant central lumbar disc protrusions can pose a significant operative challenge. Clinically, these patients are at risk of permanent disability, due not only to preoperative neural compromise caused by the protrusion itself but also to the potential iatrogenic risks associated with the standard extradural microdiscectomy technique. This is the first report to date of a giant central L3/4 disc protrusion being successfully treated through a transdural microdiscectomy approach. Prior to this report, there have been just two cases describing its application in the lumbar spine. However, neither of these reports has described its use below the level of L2/3. We compare our surgical technique with these authors and discuss the pros and cons of this surgical approach relative to the standard extradural microdiscectomy technique. Overall, we have observed encouraging results from this approach and this report would support a role for further investigation into this rarely used technique

Bayesian photon counting with electron-multiplying charge coupled devices (EMCCDs)

The EMCCD is a CCD type that delivers fast readout and negligible detector noise, making it an ideal detector for high frame rate applications. Because of the very low detector noise, this detector can potentially count single photons. Considering that an EMCCD has a limited dynamical range and negligible detector noise, one would typically apply an EMCCD in such a way that multiple images of the same object are available, for instance, in so called lucky imaging. The problem of counting photons can then conveniently be viewed as statistical inference of flux or photon rates, based on a stack of images. A simple probabilistic model for the output of an EMCCD is developed. Based on this model and the prior knowledge that photons are Poisson distributed, we derive two methods for estimating the most probable flux per pixel, one based on thresholding, and another based on full Bayesian inference. We find that it is indeed possible to derive such expressions, and tests of these methods show that estimating fluxes with only shot noise is possible, up to fluxes of about one photon per pixel per readout.Comment: Fixed a few typos compared to the published versio

Index-driven XML data integration to support functional genomics

We identify a new type of data integration problem that arises in functional genomics research in the context of large-scale experiments involving arrays, 2-dimensional protein gels and mass-spectrometry. We explore the current practice of data analysis that involves repeated web queries iterating over long lists of gene or protein names. We postulate a new approach to solve this problem, applicable to data sets stored in XML format. We propose to discover data redundancies using an XML index we construct and to remove them from the results returned by the query. We combine XML indexing with queries carried out on top of relational tables. We believe our approach could support semi-automated data integration such as that required in the interpretation of large-scale biological experiments

Quantifying the expected value of uncertain management choices for over-abundant Greylag Geese

In many parts of the world, conservation successes or global anthropogenic changes have led to increasing native species populations that then compete with human resource use. In the Orkney Islands, Scotland, a 60-fold increase in Greylag Goose Anser anser numbers over 24 years has led to agricultural damages and culling attempts that have failed to prevent population increase. To address uncertainty about why populations have increased, we combined empirical modelling of possible drivers of Greylag Goose population change with expert-elicited benefits of alternative management actions to identify whether to learn versus act immediately to reduce damages by geese. We built linear mixed-effects models relating annual goose densities on farms to land-use and environmental covariates and estimated AICc model weights to indicate relative support for six hypotheses of change. We elicited from experts the expected likelihood that one of six actions would achieve an objective of halting goose population growth, given each hypothesis for population change. Model weights and expected effects of actions were combined in Value of Information analysis (VoI) to quantify the utility of resolving uncertainty in each hypothesis through adaptive management and monitoring. The action with the highest expected value under existing uncertainty was to increase the extent of low quality habitats, whereas assuming equal hypothesis weights changed the best action to culling. VoI analysis showed that the value of learning to resolve uncertainty in any individual hypothesis for goose population change was low, due to high support for a single hypothesis of change. Our study demonstrates a two-step framework that learns about the most likely drivers of change for an over-abundant species, and uses this knowledge to weight the utility of alternative management actions. Our approach helps inform which strategies might best be implemented to resolve uncertainty when there are competing hypotheses for change and competing management choices

Informed actions: Where to cost effectively manage multiple threats to species to maximize return on investment

Conservation practitioners, faced with managing multiple threats to biodiversity and limited funding, must prioritize investment in different management actions. From an economic perspective, it is routine practice to invest where the highest rate of return is expected. This return-on-investment (ROI) thinking can also benefit species conservation, and researchers are developing sophisticated approaches to support decision-making for cost-effective conservation. However, applied use of these approaches is limited. Managers may be wary of "black-box'' algorithms or complex methods that are difficult to explain to funding agencies. As an alternative, we demonstrate the use of a basic ROI analysis for determining where to invest in cost-effective management to address threats to species. This method can be applied using basic geographic information system and spreadsheet calculations. We illustrate the approach in a management action prioritization for a biodiverse region of eastern Australia. We use ROI to prioritize management actions for two threats to a suite of threatened species: habitat degradation by cattle grazing, and predation by invasive red foxes (Vulpes vulpes). We show how decisions based on cost-effective threat management depend upon how expected benefits to species are defined and how benefits and costs co-vary. By considering a combination of species richness, restricted habitats, species vulnerability, and costs of management actions, small investments can result in greater expected benefit compared with management decisions that consider only species richness. Furthermore, a landscape management strategy that implements multiple actions is more efficient than managing only for one threat, or more traditional approaches that don't consider ROI. Our approach provides transparent and logical decision support for prioritizing different actions intended to abate threats associated with multiple species; it is of use when managers need a justifiable and repeatable approach to investment

Cognitive improvement following repair of a basal encephalocele.

We report the case of a 55-year-old woman presenting with progressive memory impairment secondary to a transsphenoidal encephalocele involving her dominant medial temporal lobe. Her clinical deterioration was accompanied by radiological progression in the encephalocele's size and associated encephalomalacia. Through a temporal craniotomy, her encephalocele was resected and the defect closed. Baseline neuropsychological assessment indicated global cognitive impairment, but post-operatively, she reported improved memory and concentration. Standardized assessment reflected an improvement in perceptual skills and an associated improved recall of a complex figure. This is the first case report to date of a patient's memory improving following treatment of a basal encephalocele

Methamphetamine Induces Striatal Cell Death Followed by the Generation of New Cells and a Second Round of Cell Death in Mice

Our laboratory has been investigating the impact of a neurotoxic exposure to methamphetamine (METH) on cellular components of the striatum post-synaptic to the dopaminergic terminals. A systemic bolus injection of METH (30 mg/kg, ip) induces the production of new cells in the striatum during a period lasting from 24-48 hours after METH. The newly generated cells arise from dormant striatal progenitors and not from the subventricular zone. The newly generated cells display glial phenotypes and begin to die 24 hours after birth, or 2.5 days post-METH. The protracted phase of cell death lasts for at least three months post-METH at which time the bulk of the newly generated cells have disappeared. The METH-induced production of new cells is associated with enlarged striatal volume (up to 50% larger than controls in some animals). As the newly generated cells die over a period of three months, the enlarged striatal volume normalizes. In conclusion, a neurotoxic dose of METH induces the generation of new cells in the striatum associated with enlarged striatal volume. The new cells die over three months post-METH and the enlarged striatal volume returns to control levels. This observation is significant because studies involving METH users show striatal enlargement and the normalization of striatal volume in METH users who have been abstinent for up to 20 months

Tight constraints on the existence of additional planets around HD 189733

We report a transit timing study of the transiting exoplanetary system HD 189733. In total we observed ten transits in 2006 and 2008 with the 2.6-m Nordic Optical Telescope, and two transits in 2007 with the 4.2-m William Herschel Telescope. We used Markov-Chain Monte Carlo simulations to derive the system parameters and their uncertainties, and our results are in a good agreement with previously published values. We performed two independent analyses of transit timing residuals to place upper mass limits on putative perturbing planets. The results show no evidence for the presence of planets down to 1 Earth mass near the 1:2 and 2:1 resonance orbits, and planets down to 2.2 Earth masses near the 3:5 and 5:3 resonance orbits with HD 189733b. These are the strongest limits to date on the presence of other planets in this system.Comment: 10 pages, 4 figures, accepted by MNRA

Factoring attitudes towards conflict risk into selection of protected areas for conservation

The high incidence of armed conflicts in biodiverse regions poses significant challenges in achieving international conservation targets. Because attitudes towards risk vary, we assessed different strategies for protected area planning that reflected alternative attitudes towards the risk of armed conflicts. We find that ignoring conflict risk will deliver the lowest return on investment. Opting to completely avoid conflict-prone areas offers limited improvements and could lead to species receiving no protection. Accounting for conflict by protecting additional areas to offset the impacts of armed conflicts would not only increase the return on investment (an effect that is enhanced when high-risk areas are excluded) but also increase upfront conservation costs. Our results also demonstrate that fine-scale estimations of conflict risk could enhance the cost-effectiveness of investments. We conclude that achieving biodiversity targets in volatile regions will require greater initial investment and benefit from fine-resolution estimates of conflict risk