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Crack development is predominant in soil structure formation. A number of fracture mechanics models have been applied to soil to describe cracking, but most are not applicable for soil in a wet, plastic state. We address this weakness by applying a new elastic–plastic fracture mechanics approach to describe crack formation in plastic soil. Samples are fractured using a deep-notch (modified four-point) bend test, with data on load transmission, sample bending, crack growth, and crack-mouth opening collected to assess the crack-tip opening angle (CTOA). CTOA provides a powerful parameter for describing soil cracking since it can be induced by soil shrinkage (an easily measured parameter) and can be used to describe elastic–plastic fracture in numerical approximations, such as finite element modelling. The test variables we studied were the direction of the applied consolidation stress, clay content, and pore water salinity. All samples were formed by consolidating soil slurry one-dimensionally with a 120-kPa vertical effective stress. Tests on pure kaolinite showed that the direction of the consolidation stress did not affect CTOA, which was 0.23 ± 0.02 m m−1 for specimens cut both in a horizontal and in a vertical direction to the applied stress. Soil clay content had a marked influence, however, with silica sand:kaolinite mixtures by weight of 20:80 and 40:60 reducing CTOA to 0.14 ± 0.02 m m−1 and 0.12 ± 0.01 m m−1, respectively. These smaller values of CTOA indicate that less strain is required to induce fracture when the amount of clay is less. Salinity (0.5 mNaCl) caused a reduction in the CTOA of pure kaolinite from 0.23 ± 0.02 m m−1 to 0.17 ± 0.03 m m−1. [ABSTRACT FROM AUTHOR]

Unlabelled: A wide spectrum of lung disease can complicate primary immunodeficiencies and early recognition influences management and prognosis. Computed tomography (CT) especially high resolution computed tomography (HRCT) has been shown to detect lung disease in adult immunodeficient patients often when the chest radiograph (CXR) is normal, but this has not been studied in children. Twenty-five CT scans [10 HRCT] and CXRs were reviewed in 23 children [14 male, 9 female] with primary immunodeficiency. Eighteen [72%] of the CT scans were abnormal, bronchiectasis being the commonest finding present in eight CT scans in patients with antibody deficiency. In eight cases CT scan revealed changes not seen on CXR (bronchiectasis; interstitial changes; small parenchymal nodules; air trapping;and a small upper lobe cyst) which influenced treatment in six cases.Conclusion: CT scans have a valuable role in assessing lung disease in children with primary immunodeficiencies and will detect important changes not visible on CXR. [ABSTRACT FROM AUTHOR]

Current sensing based on the Faraday effect in optical fibres is a well-established area in the landscape of sensor technologies. However, the optical behaviour that sets an upper limit on the detection bandwidth is often overlooked. The underlying mechanisms are explored in this reported analysis to raise awareness about their impact on the measurement results. The findings show that the Faraday effect cancellation and pulse broadening grow with increasing signal frequency, which result in suppression and distortion of the optical response. A correction factor is proposed for alternating and pulsed signals when using the simplified equation, to maintain an accurate measure of the peak current. [ABSTRACT FROM AUTHOR]

Aims: To evaluate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements made with the Goldmann applanation tonometer (GAT), Tono-Pen XL ocular blood flow tonograph (OBF), and Canon TX- 10 non-contact tonometer (NCT). Methods: CCT was recorded for either eye (randomly selected) of each of 105 untreated patients with ocular hypertension and glaucoma attending the glaucoma research unit at Moorfields Eye Hospital. For each of the selected eyes, IOP was measured with the GAT (two observers), Tono-Pen, OBF, and NCT in a randomised order. The relation of measured IOP and of inter-tonometer differences with CCT and subject age was explored by linear regression analysis. Results: A significant association between measured IOP and CCT was found with each instrument. The change in measured IOP for a 10 μm increase in CCT was 0.28, 0.31, 0.38, and 0.46 for the GAT, Tono-Pen, OBF, and NCT, respectively (all p⩽0.05). There was a significant association between the NCT/GAT differences and CCT, with a tendency of NCT to overestimate GAT in eyes with thicker corneas. There was a significant association between GAT/Tono-Pen and OBF/Tono-Pen differences and age, with a tendency of OAT and OBF to overestimate the Tono-Pen in eyes of older subjects. Conclusion: IOP measurement by all four methods is affected by CCT. The NCT is affected by CCT significantly more than the GAT. Subject age has a differential effect on the IOP measurements made by the OAT and OBF compared to the Tono-Pen. [ABSTRACT FROM AUTHOR]

A flexible technique to periodically perturb the evolution of differential phase in birefringent optical microfibre is proposed. This conceptual demonstration offers a simple yet effective solution to rectify nonideal microfibre coil sensor heads for high-performance current sensing. [ABSTRACT FROM AUTHOR]

Presented is a compact and robust temperature sensor based on an optical microfibre to coil resonator packaged around a Teflon tube. The probe can efficiently slide along electrical wires to map the local temperature for locating insulation faults and reporting high current surges. A temperature responsivity of 95 pm/°C up to ~80°C was demonstrated. This sensor is potentially low cost and simple to fabricate, making it attractive for domestic and industrial applications. [ABSTRACT FROM AUTHOR]

The optimisation of resonantly enhanced Faraday rotation in microfibre loop resonators with linear birefringence is presented. For a sufficiently large birefringence-induced resonance separation, the evolution of differential phase between the two orthogonal polarisations can lead to efficient Faraday rotation when the loop circumference is a quarter of the polarisation beat length and the round-trip phase of the eigenmode in the fast axis is 3π/2 plus an integer multiple of 2π. This reported study provides the groundwork for fabricating microfibre loop resonator based current sensors that can operate efficiently despite the presence of birefringence. [ABSTRACT FROM AUTHOR]

PurposeCharacterization of the biomechanical properties of the human eye has a number of potential utilities. One novel purpose is to provide the basis for development of suitable tissue-mimicking material. The purpose of this study was to determine the indentation and needle insertion characteristics on human eye globes and tissue strips.MethodsAn indenter assessed the elastic response of human eye globes and tissue strips under increasing compressive loads. Needle insertion determined the force (N) needed to penetrate various areas of the eye wall.ResultsThe results demonstrated that globes underwent slightly greater indentation at the midline than at the central cornea, and corneal strips indented twofold more than scleral strips, although neither difference was significant (P=0.400 and P=0.100, respectively). Significant differences were observed among various areas of needle insertion (P<0.001). Needle insertion through the anterior sclera (adjacent to the limbus) and posterior sclera (adjacent to the optic nerve) required the greatest amount of force (0.954 and 1.005 N, respectively). The force required to penetrate the central cornea (0.518 N) was significantly lower than all other areas except the midline sclera (0.700 N)ConclusionThese data form the basis for further research into the development of a tissue-mimicking human eye construct with potential utility as a model for use in ophthalmology research and surgical teaching. [ABSTRACT FROM AUTHOR]

An early diagnosis and multidisciplinary team approach are mandatory in the management of eating disorders. Serious organic symptoms and nutritional effects can mimic a systemic illness, particularly in those with atypical presentations. A 15-y-old adolescent male presented with poor growth, low weight, abdominal pain and yellow pigmentation. Further bizarre multi-system symptomatology resulted in a protracted admission with multiple investigations. An initial diagnosis of teratoma proved negative on abdominal laparotomy. A multidisciplinary approach followed by a feeding challenge led to the diagnosis of an eating disorder. The disorder, although more common in girls and adolescents, is increasing in incidence in both males and younger children. IConclusion: Atypical eating disorders are potentially serious and life-threatening illnesses, and paediatricians and psychologists should be aware of unusual presentations. [ABSTRACT FROM AUTHOR]