Computer modelling of the development of the trabecular architecture in the human pelvis

The influence of mechanical loading upon bone growth and remodelling has been widely studied. It has been suggested that functional bone growth is evident within the human adult pelvis, where the internal trabecular structure is purported to align to the principal strain trajectories induced during bipedal locomotion. Ontogenetic studies of the juvenile pelvis have observed that trabecular bone growth becomes progressively ordered from  an initial randomised patterning. This has lead to theories linking the gradual structural optimisation of  trabecular bone to the mechanical forces associated with the development of juvenile locomotion. However, recent studies have observed partially optimised trabecular structures within the human fetal and neonatal  pelvis, in contrast to previous observations. The possible genetic and mechanical factors which cause the in utero formation of these trabecular structures, which are usually associated with a weight bearing function,  remains unknown. Therefore, this thesis aimed to investigate the influence of the mechanical strains associated with juvenile movements, upon the growth of pelvic trabecular bone.Biomechanical analyses were performed on digitised models of juvenile pelvic specimens belonging to the  Scheuer collection. Digitised models of a prenatal, 1 year, 8 year and 19 year old pelvis were constructed  through processing mircocomputed tomography scan data. A geometric morphometric reconstruction technique was devised which enabled the creation of hemi-pelvic models from originally disarticulated bone specimens. This reconstruction technique was validated through a close morphological comparison between a  reconstructed hemi-pelvis, and its originally articulated CT data. The muscular and joint forces associated with  in utero movements and bipedal locomotion, were computed through musculoskeletal simulations. A prenatal  musculoskeletal model was constructed to replicate the in utero mechanical environment, and simulated  interactions between the fetal leg and the womb wall. The forces associated with bipedal locomotion were  evaluated through analysis of a pre-defined subject-specific musculoskeletal model. An attempt was made to  validate the modelling technique of altering generic musculoskeletal models to create subject-specific  representations. However, comparisons between computed and experimentally recorded muscle activities  proved inclusive, although this was attributed to uncertainties in the accuracy of the experimental data. A series of finite element analyses computed the strain distributions associated with the predicted musculoskeletal  loading. A range of load regimes were applied to each juvenile pelves, and were based upon the computed  musculoskeletal forces and the maximum isometric force capabilities of the pelvic muscles. However, despite  the differences between the applied load regimes, the predicted von Mises and compressive strain distributions  displayed similarities for all the ages analysed. All the predicted distributions were characterised  by high strains within the inferior ilium, which correlated to a region of high trabecular organisation. The high  strain magnitudes then travelled superiorly in either a gradual or rapid dissipation, both of which did not  produce a distribution which correlated to the pelvic trabecular histomorphometry. Therefore, no strain  distribution was predicted with divergence of the inferior strains to the anterior and posterior regions of the ilium,  as observed with the trabecular trajectories within the pelvis.As the predicted von Mises and compressive strain distributions failed to match the complete iliac trabecular  histomorphometry, it was suggested that the in utero formation of partially optimised trabecular growth is  possibly due to generic factors. This thesis provided initial investigations into the musculoskeletal and  mechanical loading of the juvenile pelvis, although future work is required to develop the applied modelling  techniques to fully determine the influence of the mechanical strains

THE ECONOMICS OF RIPARIAN MANAGEMENT: A LITERATURE REVIEW

Resource /Energy Economics and Policy,

The relationship of general retention ability to new South African group test non-verbal/verbal IQ discrepancies and their academic correlates

Both experimental research (Robbertse,1952)and clinical observation (Kruger, 1972; van der Merwe,1978) have indicated that pupils with a Verbal IQ score 10 or more points lower than their non-Verbal IQ (termed a 'Type 1' discrepancy in the present research) on the New South African Group Test (NSAGT) show poorer academic achievement than their peers of similar ability. The present research investigates the relationship of general retention ability, as defined by Hakstian and Cattell (1978), to Type 1 discrepancies as well as to their academic correlates. One hundred and thirty-nine standard seven English-speaking boys were tested on the NSAGT and the Junior Aptitude Test (JAT) (of which tests 8 and 9 give an indication of general retention ability) and divided into a group with Type 1 discrepancies and two control groups. All three groups were matched on full-scale IQ. Comparison of these three groups, using the analysis of variance technique, showed that there was no significant difference between them in level of general retention ability or in academic performance (measured by average percentage in the final standard seven examination). While no significant difference was found between the three groups regarding the relationship of general retention ability to academic performance, in the Type 1 discrepancy group the relationship of rote memory (JAT test 8) to academic performance differed markedly from that of associative memory (JAT test 9) to academic performance. In the Type 1 discrepancy group rote memory was highly associated with academic performance, possibly indicating a compensatory strategy for the lower Verbal ability in this group, enabling it to achieve academically on par with the control groups, contrary to what would be expected on the basis of Robbertse's (1962) findings. In terms of Jensen's (1982) Level 1/Level 11 theory of intelligence, it appears from the present research that rote memory ability (JAT test 8) varies between being a Level 11 ability (in the Type 1 discrepancy group) to acting as a Level 1 ability in the two control groups. The present research questions Verwey and Wolmarans's (1980) description of both JAT tests 8 and 9 as simple measures of retention Test 9, in particular, appears to function consistently as a Level 11 ability

Patient preferences regarding prophylactic cranial irradiation: A discrete choice experiment

Introduction: In patients with non-small cell lung cancer (NSCLC) treated with chemoradiotherapy (CRT), prophylactic cranial irradiation (PCI) is not standard practice. This study determined patient preferences for PCI with respect to survival benefit, reduction in brain metastases (BM) and acceptable toxicity.  Methods: A Discrete Choice Experiment was completed pre- and post-treatment. Patients made 15 hypothetical choices between two alternative PCI treatments described by four attributes: amount of life gained, chance of BM, ability to care for oneself, and loss of memory. Participants also chose between PCI and no PCI.  Results: 54 and 46 surveys were completed pre- and post-treatment. The most important attributes pre-treatment were: a survival benefit >6 months, of 3–6 months, avoiding severe problems with memory and self-care, avoiding quite a bit of difficulty with memory and maximally reducing BM recurrence. Post-treatment, BM reduction became more important. 90% of patients would accept PCI for a survival benefit >6 months, with a maximal reduction in BM even if severe memory/self-care problems occurred. With a 10% reduction in BM and mild problems with memory and self-care 70% of patients pre- (90% post-treatment) would accept PCI for a survival benefit of 1–3 months, and 52% pre- (78% post-treatment) for no survival benefit.  Conclusion: Improvement in survival is the most important attribute of PCI with patients willing to accept significant toxicity for maximum survival and less toxicity for less survival benefit. BM reduction became more important after treatment. The majority of patients would accept PCI for no survival benefit and a reduction in BM

Response of winter climate and extreme weather to projected Arctic sea-ice loss in very large-ensemble climate model simulations

Very large (~2000 members) initial-condition ensemble simulations have been performed to advance understanding of mean climate and extreme weather responses to projected Arctic sea-ice loss under 2 °C global warming above preindustrial levels. These simulations better sample internal atmospheric variability and extremes for each model compared to those from the Polar Amplification Model Intercomparison Project (PAMIP). The mean climate response is mostly consistent with that from the PAMIP multi-model ensemble, including tropospheric warming, reduced midlatitude westerlies and storm track activity, an equatorward shift of the eddy-driven jet and increased mid-to-high latitude blocking. Two resolutions of the same model exhibit significant differences in the stratospheric circulation response; however, these differences only weakly modulate the tropospheric response. The response of temperature and precipitation extremes largely follows the seasonal-mean response. Sub-sampling confirms that large ensembles (e.g. ≥400) are needed to robustly estimate the seasonal-mean large-scale circulation response, and very large ensembles (e.g. ≥1000) for regional climate and extremes

Degradation and forgone removals increase the carbon impact of intact forest loss by 626%

Intact tropical forests, free from substantial anthropogenic influence, store and sequester large amounts of atmospheric carbon but are currently neglected in international climate policy. We show that between 2000 and 2013, direct clearance of intact tropical forest areas accounted for 3.2% of gross carbon emissions from all deforestation across the pantropics. However, full carbon accounting requires the consideration of forgone carbon sequestration, selective logging, edge effects, and defaunation. When these factors were considered, the net carbon impact resulting from intact tropical forest loss between 2000 and 2013 increased by a factor of 6 (626%), from 0.34 (0.37 to 0.21) to 2.12 (2.85 to 1.00) petagrams of carbon (equivalent to approximately 2 years of global land use change emissions). The climate mitigation value of conserving the 549 million ha of tropical forest that remains intact is therefore significant but will soon dwindle if their rate of loss continues to accelerate

Estimating a sub-mesoscale diffusivity using a roughness measure applied to a tracer release experiment in the Southern Ocean

We test the use of a measure to diagnose a sub-mesoscale isopycnal diffusivity by determining the best match between observations of a tracer and simulations with varying small-scale diffusivities. Specifically, the robustness of a ‘roughness’ measure to discriminate between tracer fields experiencing different sub-mesoscale isopycnal diffusivities and advected by scaled altimetric velocity fields is investigated. We use the measure to compare numerical simulations of the tracer released at a depth of about 1.5 km in the Pacific sector of the Southern Ocean during the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) field campaign with observations of the tracer taken on DIMES cruises. We find that simulations with an isopycnal diffusivity of ~20 m2s−1 best match observations in the Pacific sector of the ACC, rising to ~20-50 m2s−1 through Drake Passage, representing sub-mesoscale processes and any mesoscale processes unresolved by the advecting altimetry fields. The roughness measure is demonstrated to be a statistically robust way to estimate a small-scale diffusivity when measurements are relatively sparse in space and time, although it does not work if there are too few measurements overall. The planning of tracer measurements during a cruise in order to maximise the robustness of the roughness measure is also considered. It is found that the robustness is increased if the spatial resolution of tracer measurements is increased with the time since tracer release

Development and assessment of a bone scanning device to enhance restraint performance

The objective of the BOSCOS (BOne Scanning for Occupant Safety) project was the development of a system that can make an assessment of the bone characteristics of each vehicle occupant in order to estimate their skeletal strengths. The seatbelt and airbag characteristics can then be adjusted to deliver optimum levels of protection specifically for each occupant. A system introduced into every vehicle has the capacity to save lives and reduce injury levels across the whole spectrum of vehicle occupants. This paper describes the contributions from academic and industrial partners to this UK Department for Transport funded project.Commercial pressure focuses restraint design on meeting legal requirements for vehicle approval, but legal requirements use dummies which do not represent the range of car occupant shapes, sizes, and driving positions. A person with lower skeletal characteristics may not be able to withstand the current fixed levels of restraint without sustaining injuries. Conversely, a person with greater skeletal characteristics may be capable of withstanding greater levels of restraint.Possible technologies that are available have been assessed for their suitability for an in-vehicle monitoring system. Accident studies have been conducted to create a baseline of statistics in terms of casualties and their injuries. Initial bone scanning studies have utilised different types of equipment and a new prototype scanner has been developed for use in a vehicle environment using ultrasound technology.Computer based occupant mathematical modelling has been used to establish the potential gains from a working system and also the requirements needed of the restraint systems toachieve these gains. In addition, bone scanning has been conducted, to determine a method to read across from scan values to skeletal condition to provide data for the optimisation of the restraint system