Hadamard Renormalisation of the Stress Energy Tensor on the Horizons of a Spherically Symmetric Black Hole Space-Time

We consider a quantum field which is in a Hartle-Hawking state propagating in a general spherically symmetric black hole space-time. We make use of uniform approximations to the radial equation to calculate the components of the stress tensor, renormalized using the Hadamard form of the Green's function, on the horizons of this space-time. We then specialize these results to the case of the `lukewarm' Reissner-Nordstrom-de Sitter black hole and derive some conditions on the stress tensor for the regularity of the Hartle-Hawking state.Comment: 18 pages, minor changes to introduction and conclusions, typos correcte

Uneven intervertebral motion sharing is related to disc degeneration and is greater in patients with chronic, non-specific low back pain. An in-vivo, cross-sectional cohort comparison of intervertebral dynamics using quantitative fluoroscopy.

Purpose: Evidence of intervertebral mechanical markers in chronic, non-specific low back pain (CNSLBP) is lacking. This research used dynamic fluoroscopic studies to compare intervertebral angular motion sharing inequality and variability (MSI and MSV) during continuous lumbar motion in CNSLBP patients and controls. Passive recumbent and active standing protocols were used and the relationships of these variables to age and disc degeneration were assessed. Methods: Twenty patients with CNSLBP and 20 matched controls received quantitative fluoroscopic lumbar spine examinations using a standardised protocol for data collection and image analysis. Composite disc degeneration (CDD) scores comprising the sum of Kellgren and Lawrence grades from L2-S1 were obtained. Indices of intervertebral motion sharing inequality (MSI) and variability (MSV) were derived and expressed in units of proportion of lumbar range of motion from outward and return motion sequences during lying, (passive) and standing (active) lumbar bending and compared between patients and controls. Relationships between MSI, MSV, age and CDD were assessed by linear correlation. Results: MSI was significantly greater in the patients throughout the intervertebral motion sequences of recumbent flexion (0.29 vs 0.22, p= 0.02) and when flexion, extension, left and right motion were combined to give a composite measure (1.40 vs 0.92, p=0.04). MSI correlated substantially with age (R=0.85, p=0.004) and CDD (R=0.70, p=0.03) in lying passive investigations in patients and not in controls. There were also substantial correlations between MSV and age (R=0.77, p=0.01) and CDD (R=0.85, p=0.004) in standing flexion in patients and not in controls. Conclusion: Greater inequality and variability of motion sharing was found in patients with CNSLBP than in controls, confirming previous studies and suggesting a biomechanical marker for the disorder at intervertebral level. The relationship between disc degeneration and MSI was augmented in patients, but not in controls during passive motion and similarly for MSV during active motion, suggesting links between in vivo disc mechanics and pain generation

Soil Properties and their Influence on Grassland Production under Low Input and Organic Farming Conditions

End of project reportThis project set out to identify soil properties that most influence grassland production under low mineral nitrogen input conditions. Sixteen farms were selected in Counties Limerick and Clare and the soil sampled. Soil physical and chemical characteristics and soil biological aspects involved in the carbon and nitrogen cycles were studied in the laboratory. Nutrient additions to farms as well as the nature of grazing by livestock (numbers, types of grazing animals, grazing practices), grassland management, and production from the farms were recorded

Aberrant intervertebral motion in patients with treatment‑resistant nonspecific low back pain: a retrospective cohort study and control comparison

Purpose Intervertebral kinematic assessments have been used to investigate mechanical causes when back pain is resistant to treatment, and recent studies have identified intervertebral motion markers that discriminate patients from controls. However, such patients are a heterogeneous group, some of whom have structural disruption, but the effects of this on intervertebral kinematics are unknown.Methods Thirty-seven patients with treatment-resistant back pain referred for quantitative fluoroscopy were matched to an equal number of pain-free controls for age and sex. All received passive recumbent flexion assessments for intervertebral motion sharing inequality (MSI), variability (MSV), laxity and translation. Comparisons were made between patient sub-groups, between patients and controls and against normative levels from a separate group of controls.Results Eleven patients had had surgical or interventional procedures, and ten had spondylolisthesis or pars defects. Sixteen had no disruption. Patients had significantly higher median MSI values (0.30) than controls (0.27, p = 0.010), but not MSV (patients 0.08 vs controls 0.08, p = 0.791). Patients who received invasive procedures had higher median MSI values (0.37) than those with bony defects (0.30, p = 0.018) or no disruption (0.28, p = 0.0007). Laxity and translation above reference limits were not more prevalent in patients.Conclusion Patients with treatment-resistant nonspecific back pain have greater MSI values than controls, especially if the former have received spinal surgery. However, excessive laxity, translation and MSV are not more prevalent in these patients. Thus, MSI should be investigated as a pain mechanism and for its possible value as a prognostic factor and/or target for treatment in larger patient populations

Individualised assessment of aberrant intervertebral mechanics

Individualised assessment of aberrant intervertebral mechanics Alan Breen Introduction: Much of low back pain is considered to be the result of soft tissue stresses in the spine [1]. However, Individualised biomechanical assessment is problematical due to the spine’s inaccessibility to non-invasive physical measurement. This has led to concern about an over-reliance on psycho-social management for people with chronic non-specific spinal pain [2]. Cadaveric experiments have explored the subtle biomechanics of disco-ligamentous sub-failure and muscle overuse caused by added physical demands [3]. There have also been attempts to accurately represent the biomechanics of the spine with mechanical models [4]. These efforts have recognised the need to access kinetic and kinematic information from the mid-range of motion rather than just at its ends. In the 1980s, the merging of fluoroscopy and image processing to overcome this problem was achieved [5]. Between then and now, systems have been improved and some consensus has been reached about how they might be operated [6]. Methods: A series of studies has been conducted into the biomechanics of the lumbar and cervical spines using this this technology, now known as ‘Quantitative Fluoroscopy’ (QF). These investigated its 2-D measurement properties in terms of conventional intervertebral kinematics, such as maximum RoM, translation and finite centre of rotation. Later, new variables were introduced, namely ‘Initial Attainment Rate (a measure of laxity in the mid-range), ‘Motion Sharing Inequality’ (MSI) throughout the range, representing intersegmental co-ordination and ‘Motion Sharing Variability’ (MSV) representing spinal control.[7] Initial sEMG studies examined the relationship to back muscle activation and QF-informed finite element (FE) loading models were generated. Results: These studies have found that most of these measurement parameters have good observer repeatability and most good intra-subject reliability, although not necessarily agreement. Laxity and MSI have so far been the best biomarkers for chronic, non-specific low back pain and its relationship to disc degeneration [7]. The FE studies have demonstrated the feasibility of more closely representing subject-specific tissue loading with such models [8] and contemporaneous sEMG studies have found relationships to spine control (MSV). Only one outcome study has so far been conducted (in the cervical spine), which found no relationship between IV-RoM change and disability score change over a treatment period [9]. Conclusion: Despite these encouraging findings, there is a great deal more work to do to establish the clinical utility of these technologies, not least in the field of spinal surgery, where ‘adjacent segment disease’ is usually attributed to aberrant motion patterns consequent to surgical procedures. The weight bearing condition has barely been explored for the lower back, but individualised FE load modelling seems a real possibility. References [1] Borenstein D (2013) Nature review. Rheumatology,9:643-653. [2] Deane JA & McGregor AH (2016) BMJ Open,2017:e011075. [3] Panjabi MM (1992) Journal of Spinal Disorders,5:390-397. [4] Bassini T et al. (2017) Journal of Biomechanics,58:89-96. [5] Breen AC, Allen, R., Morris, A. (1988) Clinical Biomechanics,3:5-10.[6] Breen AC et al. (2012) Advances in Orthopaedics,1-10. [7] Breen AC, Breen, Ax.C. (2017) European Spine Journal,doi:10.1007/s00586-017-5155-y: [8] Zanjani-Pour S, Meakin, J,R,, Breen, Ax., Breen A. (accepted) Journal of Biomehcanics, [9] Branney J & Breen AC (2014) Chiropractic & Manual Therapies,22:24

YouTube or YouLose? Can YouTube Survive a Copyright Infringement Lawsuit

YouTube, and similar video web hosting services, have already been targets of copyright infringement lawsuits. YouTube’s liability is most likely dependant on whether the service meets the requirements of the DMCA safe harbor for service providers under 17 U.S.C.A. § 512(c). This paper briefly examines how YouTube would fare under the different theories of copyright infringement and discusses whether the DMCA safe harbor would be available to YouTube if they were found liable as an infringer. The limited case law available indicates that the DMCA safe harbor will likely facilitate YouTube’s continued existence, unlike services like Grokster, although YouTube would likely be found vicariously liable for copyright infringement