Humidity sensing by optically interfacing with spectrally absorptive materials

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The measurement of humidity is rapidly increasing in importance in physical, chemical and biological processes as industry attempts to improve quality and production rates by better control of relative humidity (RH). A novel optical fibre humidity sensor suitable for use in an optical fibre multi-point distributed sensing system has been developed, thus for the first time allowing multipoint measurements of humidity along an optical fibre which can be distributed within an industrial plant or machine without the need for electrical power supplies. The novel point sensor is based on the principle of using the absorption spectrum of a colorimetric reagent (cobalt chloride) immobilised on the surface of the core of a multimode optical fibre by employing a thin gelatin film. The single point sensor has an insertion loss of less than 0.2 dB. Two-wavelength detection is employed to provide referencing to eliminate common mode intensity variation. The basic design, construction and testing of an experimental sensor in the humidity region 20 to 80% RH and temperature range 25 to 50 °C is described. Resolution and Repeatability can be better than 2% RH with a time constant of 0.5 second. A two-wavelength optical time domain reflectometer (OTDR) has been developed and a four-sensor network has been built. The resolution of measurement on the network can be better than 4% RH, but because of noise in the OTDR the resolution value is dependent on averaging time in the instrument.Funding was obtained from EPSRC

Towards wireless technology for safety critical systems.

Wireless technology provides an unprecedented level of design flexibility for new system designs and legacy system updates. However, there are several challenges which present themselves when adopting wireless technologies for use in safety systems. This paper elaborates on available design techniques which can resolve the implementation issues for a given application, to ensure data communication between nodes is safe (deterministic), secure, reliable and available.N/

Timing error detection and correction for power efficiency: an aggressive scaling approach

Low-power consumption has become an important aspect of processors and systems design. Many techniques ranging from architectural to system level are available. Voltage scaling or frequency boosting methods are the most effective to achieve low-power consumption as the dynamic power is proportional to the frequency and to the square of the supply voltage. The basic principle of operation of aggressive voltage scaling is to adjust the supply voltage to the lowest level possible to achieve minimum power consumption while maintaining reliable operations. Similarly, aggressive frequency boosting is to alter the operating frequency to achieve optimum performance improvement. In this study, an aggressive technique which employs voltage or frequency varying hardware circuit with the time-borrowing feature is presented. The proposed technique double samples the data to detect any timing violations as the frequency/voltage is scaled. The detected violations are masked by phase delaying the flip-flop clock to capture the late arrival data. This makes the system timing error tolerant without incurring error correction timing penalty. The proposed technique is implemented in a field programmable gate array using a two-stage arithmetic pipeline. Results on various benchmarks clearly demonstrate the achieved power savings and performance improvement.N/

Small RNA signatures of the anterior cruciate ligament from patients with knee joint osteoarthritis

ABSTRACT The anterior cruciate ligaments are susceptible to degeneration, resulting in pain, reduced mobility and development of the degenerative joint disease osteoarthritis. There is currently a paucity of knowledge on how anterior cruciate ligament degeneration and disease can lead to osteoarthritis. Small non-coding RNAs (sncRNAs), such as microRNAs, and small nucleolar RNA, are important regulators of gene expression. We aimed to identify sncRNA profiles of human anterior cruciate ligaments to provide novel insights into their roles in osteoarthritis. RNA was extracted from the anterior cruciate ligaments of non-osteoarthritic knee joints (control) and end-stage osteoarthritis knee joints, used for small RNA sequencing and significantly differentially expressed sncRNAs defined. Bioinformatic analysis was undertaken on the differentially expressed miRNAs and their putative target mRNAs to investigate pathways and biological processes affected. Our analysis identified 184 sncRNA that were differentially expressed between control ACLs derived from osteoarthritic joints with a false discovery adjusted p value<0.05; 68 small nucleolar RNAs, 26 small nuclear RNAs and 90 microRNAs. We identified both novel and previously identified (miR-206, –101, –365 and –29b and –29c) osteoarthritis-related microRNAs and other sncRNAs (including SNORD74, SNORD114, SNORD72) differentially expressed in ligaments derived from osteoarthritic joints. Significant cellular functions deduced by the differentially small nuclear RNAs and 90 microRNAs. We identified expressed miRNAs included differentiation of muscle (P<0.001), inflammation (P<1.42E-10), proliferation of chondrocytes (P<0.03), fibrosis (P<0.001) and cell viability (P<0.03). Putative mRNAs were associated with the canonical pathways ‘Hepatic Fibrosis Signalling’ (P<3.7E-32), and ‘Osteoarthritis’ (P<2.2E-23). Biological processes included apoptosis (P<1.7E-85), fibrosis (P<1.2E-79), inflammation (P<3.4E-88), necrosis (P<7.2E-88) and angiogenesis (P<5.7E-101). SncRNAs are important regulators of anterior cruciate disease during osteoarthritis and may be used as therapeutic targets to prevent and manage anterior cruciate ligament disease and the resultant osteoarthritis

The molecular and cellular differences between tendons and ligaments

Tendons and ligaments play key roles in the musculoskeletal system in both man and animals. Both tissues can often be injured as result of contact based accidents or ageing and disease, causing discomfort, pain and increased susceptibility to degenerative joint disease. To date, tendon and ligament biology is relatively under-studied in healthy, non-diseased tissues. This information is essential to understand the pathology of these tissues and vital for future development of tendon and ligament tissue-engineered structures. This thesis aims to investigate the molecular and cellular differences between tendons and ligaments around the canine stifle joint. The biochemical composition, structural, and morphological characteristics were identified between the different regions of the intra- articular cranial cruciate ligament (CCL) and extra-articular medial collateral ligament (MCL), and the positional long digital extensor tendon (LDET) and energy storing superficial digital flexor tendons (SDFT). Differences in proteome composition were also assessed between CCL and LDET. Cells isolated from canine CCL and LDET were cultured in a 3D in vitro fibrin culture model and measured for differences in structural, biochemical and proteome composition. Statistical significant differences in extracellular matrix (ECM) composition in terms of glycosaminoglycan (GAG) and elastin content were primarily detected in CCL in comparison to the other three tissues. The CCL was also found to have morphological differences including less compact collagen architecture, differences in cell nuclei phenotype, and increased (GAG) and elastin content. Proteomic comparison between CCL and LDET resulted in significantly abundant fibrocartilage proteins such as collagen type II, aggrecan, versican and chondroadherin in CCL, while the LDET was more abundant in asporin and thrombospondin-4. 3D tendon and ligament constructs were able to recapitulate tendon and ligamentous tissue characteristics particularly with regards to ECM proteins present, however both construct were less abundant in ECM protein and contained a greater proportion of cellular proteins, corresponding with low collagen and high level of DNA content measured in both constructs. 3D tendon and ligament constructs derived from tendon and ligament cells had similar ECM, proteomic and structural composition, indicating that cell source may not be an important factor for tendon or ligament tissue engineering

3D photogrammetric images to evaluate foot morphology and ankle kinematics during gait of Middle Eastern adults

To prevent high fall rates, foot injury and ankle sprain during daily activities and sport, footwear should be designed based on foot shape and ankle kinematics. The purpose of this thesis is to develop an accurate3D photogrammetric images captured by smartphone cameras technique that is non-invasive, low-cost and high-quality to analyse the morphology of the foot surface, investigate the foot shape characteristics of both genders, and evaluate the medial longitudinal arch (MLA) in static and dynamic conditions. Furthermore, the validation and investigation of ankle kinematics during gait according to gender is undertaken, as is an assessment of ankle kinematics in normal and unsteady gait. The photogrammetry technique utilises images of objects captured by multiple cameras from differing viewpoints to produce a digital 3D model of objects. In photogrammetry, camera calibration is an important step to improve the accuracy of measured imaged coordinates (x, y). This system calibration process involves individual calibrations of 7-Galaxy smartphones and the internal accuracy is 0.36 pixels. In this study, 33 healthy voluntary participants (18 males and 15 females, aged between 25and 47years), all of whom were Middle Eastern postgraduate students at the University of Southern Queensland (USQ) were recruited. In clinical settings, a number of landmarks were mounted on foot skin to measure the angles and the distances between anatomical bone locations. The results indicated that there were significant differences in some morphological characteristics of the feet of each gender. For example, the mean value of the foot length of males (26.01cm) was larger than females (22.39cm), and the mean values of arch length, ankle height and Chippaux-Smirak ratio for males was higher than for females. An accurate geometrical 3D close-range photogrammetry (CRP) method was used to evaluate the MLA in static (50% weight-bearing (WB), 10% WB, 90% WB standing and sitting non-WB) and dynamic motion during gait. MLA angle differences between males and females in static and dynamic conditions were also measured. In the static condition, the observation of the MLA angle was lower at about (137°)when sitting, indicating that the MLA was higher in non-WB. In the dynamic condition during walking, the higher mean value was found in the mid-stance phase (150.57°) when the foot tended to flatten. The results of ankle kinematics during walking refer to significant differences between females and males for the transverse plane of range of motion of the ankle (F=12.21, Sig=0.013) however no significant differences of coronal and sagittal planes were found between genders. The CRP technique was also used to measure ankle kinematics during normal gait and three unsteady gait trials ((1) eyes closed,(2) on single beam, and (3) dragging ankle weights) in four phases of stance. We found that the eyes closed gait had higher ankle kinematic values than other gait conditions in the heel strike phase(3.38°, 11.72° and 8.48°) of the coronal, sagittal and transverse planes, respectively. Overall, the study was appropriate because it used a novel precise 3D images technique to evaluate foot morphology and ankle kinematics during gait

Postnatal mechanical loading drives adaptation of tissues primarily through modulation of the non-collagenous matrix

Mature connective tissues demonstrate highly specialised properties, remarkably adapted to meet their functional requirements. Tissue adaptation to environmental cues can occur throughout life and poor adaptation commonly results in injury. However, the temporal nature and drivers of functional adaptation remain undefined. Here, we explore functional adaptation and specialisation of mechanically loaded tissues using tendon; a simple aligned biological composite, in which the collagen (fascicle) and surrounding predominantly non-collagenous matrix (interfascicular matrix) can be interrogated independently. Using an equine model of late development, we report the first phase-specific analysis of biomechanical, structural, and compositional changes seen in functional adaptation, demonstrating adaptation occurs postnatally, following mechanical loading, and is almost exclusively localised to the non-collagenous interfascicular matrix. These novel data redefine adaptation in connective tissue, highlighting the fundamental importance of non-collagenous matrix and suggesting that regenerative medicine strategies should change focus from the fibrous to the non-collagenous matrix of tissue