Quantification of Optical Clarity of Transparent Soil Using the Modulation Transfer Function

Transparent synthetic soils have been developed as a soil surrogate to enable internal visualization of geotechnical processes in physical models. Transparency of the soil dictates the overarching success of the technique; however, despite this fundamental requirement, no quantitative framework has yet been established to appraise the visual quality of transparent soil. Previous approaches to assess and optimize transparency quality included an eye chart assessment method, although this approach is highly subjective and operator-dependent. In this paper, an independent method for quantitatively assessing the optical quality of transparent soil is proposed based on the optical calibration method, Modulation Transfer Function (MTF). The work explores this hypothesis and assesses the potential for MTF to quantify the optical quality of transparent soils for a number of aspects including (i) optimum oil blend ratio, (ii) depth of viewing plane, and (iii) temperature. The results confirmed that MTF offers a robust and reliable method to provide an independent quantitative measure of the optical quality of transparent soil. The impact of reduced soil transparency and the ability to track speckle patterns—thus accuracy and precision of displacement measurement—was correlated with MTF to evaluate the permissible viewing depth of transparent soil

Bounded Arithmetic in Free Logic

One of the central open questions in bounded arithmetic is whether Buss' hierarchy of theories of bounded arithmetic collapses or not. In this paper, we reformulate Buss' theories using free logic and conjecture that such theories are easier to handle. To show this, we first prove that Buss' theories prove consistencies of induction-free fragments of our theories whose formulae have bounded complexity. Next, we prove that although our theories are based on an apparently weaker logic, we can interpret theories in Buss' hierarchy by our theories using a simple translation. Finally, we investigate finitistic G\"odel sentences in our systems in the hope of proving that a theory in a lower level of Buss' hierarchy cannot prove consistency of induction-free fragments of our theories whose formulae have higher complexity

Enhancing accuracy and precision of transparent synthetic soil modelling

Over recent years non-intrusive modelling techniques have been developed to investigate soil-structure interaction problems of increasingly complex geometry. This paper concerns the development of a small-scale, 1 g, modelling technique using a transparent analogue for soil with particle image velocimetry for internal displacement measurement. Larger model geometry achieved in this research using fine-grained transparent synthetic soils has led to an increased need for rigorous photogrammetric correction techniques. A correction framework, based upon a modified version of the pinhole camera model, is presented that corrects for lens and camera movement induced errors as well as scaling from image space to object space. An additional statistical approach is also developed to enhance the system precision, by minimising the impact of increased non-coplanarity between the photogrammetry control plane and the target plane. The enhanced data correction and statistical precision is demonstrated using a case study examining the failure mechanism around a double helical screw pile installed in transparent synthetic soil representative of a soft clay

Burden of hydrocoele assessed from medical and surgical records in a lymphatic filariasis endemic country, Samoa

Background: Samoa is a Pacific Island country that has long been known to have a high burden of lymphatic filariasis. Little has been documented about the burden of disability due to the chronic complications of the disease. We examined the rates of hydrocoele amongst the Samoan male population to better understand the situation. Methods: Information on numbers of suspected hydrocoele cases in men aged 18 years and older from 2006 to 2013 was sought using ICD-10 codes and/or keywords from three sources: the hospital patient information system plus the surgical clinic and operating theater records in Tupua Tamasese Meaole and Malietoa Tanumafili II hospitals in Samoa. Chart review of suspected hydrocoele cases was used to confirm the diagnosis of hydrocoele amongst suspected cases. The following data items were extracted from patient records where available: date of diagnosis, age, village, hydrocoele characteristics (duration, size, and volume), history and cause of injuries, whether lymphatic filariasis was a differential diagnosis, whether ultrasound scan was used to verify diagnosis, and details of any surgery performed. Population data were obtained from the Samoa Bureau of Statistics. Results: There were 535 suspected cases identified from the 3 sources between 2006 and 2013, of which 328 were diagnosed as hydrocoele; charts for 56 suspected cases (10.5%) could not be located. The mean age of men with hydrocoele was 49.2 years. The proportion of men aged ≥ 18 years diagnosed with hydrocoele over the study period was 0.62% (328/52,944). North West Upolu had the highest proportion amongst the four regions of Samoa (p < 0.001). The proportion of men presenting with hydrocoele increased with age (p < 0.001). 14.3% of patients had an injury that could have contributed to the hydrocoele. Only 4.0% of all patient records had lymphatic filariasis recorded as a differential diagnosis. 60.7% of all patients with hydrocoele had some form of surgery, with no difference between regions (p = 0.276). The majority of surgeries were hydrocoelectomies, where the tunica vaginalis is everted. The mean age of patients that had surgery was 48.2 years. It was difficult to estimate hydrocoele size and duration due to non-standardized way of reporting. Conclusions: This study used multiple sources to document the number of hydrocoele cases that presented annually to medical facilities in Samoa. This represents a minimum estimate of the burden since some cases may have not presented for treatment. The numbers presenting have fluctuated over the years (2006 to 2013), and improvements in the reporting system are needed. The health system needs to consider ways to address a large number of patients that still require surgery, as well as conducting follow-up of those that did receive surgery. Additionally, clinicians should consider lymphatic filariasis as a differential diagnosis for hydrocoeles

Fluid Ontologies in the Search for MH370

This paper gives an account of the disappearance of Malaysian Airways Flight MH370 into the southern Indian Ocean in March 2014 and analyses the rare glimpses into remote ocean space this incident opened up. It follows the tenuous clues as to where the aeroplane might have come to rest after it disappeared from radar screens – seven satellite pings, hundreds of pieces of floating debris and six underwater sonic recordings – as ways of entering into and thinking about ocean space. The paper pays attention to and analyses this space on three registers – first, as a fluid, more-than-human materiality with particular properties and agencies; second, as a synthetic situation, a composite of informational bits and pieces scopically articulated and augmented; and third, as geopolitics, delineated by the protocols of international search and rescue. On all three registers – as matter, as data and as law – the ocean is shown to be ontologically fluid, a world defined by movement, flow and flux, posing intractable difficulties for human interactions with it

Centrifuge modelling of the effects of root geometry on transpiration-induced suction and stability of vegetated slopes

Shallow landslides (i.e., 1 - 2 m depth) on both man-made and natural slopes are of major concern worldwide that has led to huge amount of socio-economical losses. The use of vegetation has been considered as an environmentally friendly means of stabilising slopes. Existing studies have focused on the use of plant roots with different geometries to mechanically stabilise soil slopes, but there are little data available on the contribution of transpiration-induced suction to slope stability. This study was designed to quantify both the hydrological and mechanical effects of root geometry on the stability of shallow slopes. Centrifuge tests were conducted to measure soil suction in slope models supported by newly-developed artificial roots. These artificial roots exhibit three different representative geometries (i.e., tap, heart and plate) and could simulate the effects of transpiration. The measured suction was then back-analysed through a series of finite element seepage-stability analyses to determine the factor of safety (FOS). It is revealed that after a rainfall event with a return period of 1000 years, the slope supported by heart-shaped roots retained the highest suction of 3 kPa within the root depth and thus this type of root provided the greatest stabilisation effects. The FOS of the slope supported by the heart-shaped roots, through both mechanical reinforcement and transpiration-induced suction, is 16% and 28% higher than that supported by the tap- and plate-shaped roots, respectively