Imaging of Mechanically Induced Thermal Heat Patterns

Imaging information obtained from nondestructive tests is becoming more widely investigated and developed. Imaging obviously has the potential to provide a more easily interpreted outcome of a nondestructive test, leading to more rapid and correct evaluation of the state of the examined material. This work presents one aspect of the field of imaging — developing a thermal image of the surface of a material subjected to mechanical vibrations. The technique of vibrothermography has been under investigation in our laboratory for several years, especially as applied to advanced composite materials. We will present in this paper a review of the imaging aspects of the technique, in particular discussing the phenomena responsible for producing a surface heat pattern and the phenomena responsible for obtaining a suitable image of this pattern. Finally, a discussion is given of the possible interpretations which may be made from the image concerning evaluation of the material condition, as may be used in a nondestructive evaluation procedure. Examples will be drawn from a number of tests performed in our laboratory

Surgical outcomes of patients with neuroblastoma in a tertiary centre in Hong Kong: A 12-year experience

Introduction: Neuroblastoma has a heterogeneous clinical course. The prognosis varies widely depending on the age of diagnosis, extent of disease and tumour biology. However, the specific clinical outcome of this disease in Hong Kong has not been well characterised thus far. Complete tumour excision has been demonstrated to confer survival benefit on patients with advanced disease even if there is metastasis. Since year 2004, we have adopted a revised, more aggressive surgical approach in managing these patients. Here, we aim to review our experience in the management of this disease. Methods: A retrospective review was performed for the past 12 years to include all patients who presented with neuroblastoma in our institution. Data such as the survival, age at diagnosis, MYCN amplification status, the extent of tumour excision, and stage of the disease were recorded and analysed. Results: 37 patients were included in this study. Overall survival of our patients was 67.6%. Patients with Stage 1, 2 and 4S have 100% survival whereas stage 4 patients only have 41.4% survival. Since our revised surgical approach in 2004, patients who had been operated had a better survival. Survival of stage 4 patients with operation after 2004 was 57.1% whereas the survival of patients at the same stage before 2004 was only 30%. Age at diagnosis, completeness of tumour excision and stage of disease are also correlated with overall prognosis. Further, patients with the presence of MYCN gene amplification have apparently poorer survival but it is not statistically significant due to the small sample size. Conclusion: The management of patients with neuroblastoma remains a challenge. Advanced stage of disease, incomplete tumour excision and increased age at diagnosis were all associated with poor survival. We demonstrated a better survival for those who underwent a more aggressive surgical approach, though this is a technically demanding and time consuming procedure. Thus, the management of advanced neuroblastoma should be centralised in a centre with combined surgical, oncological and paediatric intensive care expertise.published_or_final_versio

3-D Wave Propagation in Cylindrical Single Crystal Solid-Liquid Bodies

The large difference in the ultrasonic velocity between the solid and the liquid phases of most semiconducting materials results in reflection/refraction of ultrasound at solid-liquid interfaces and an interest in using laser ultrasonics for sensing solid-liquid interfaces during single crystal growth. Using a ray tracing analysis, a set of measured ultrasonic time of flight (TOF) projection data can yield the ray paths connecting the source to the receiver, which can subsequently be used to reconstruct the solid-liquid interface. In previous work [1] 2-D wave propagation in cylindrical single crystal solid-liquid bodies was used to explore the feasibility of using ultrasound to characterize solid-liquid interfaces during vertical Bridgman growth of semiconductor materials. Detailed study of ray paths, wavefronts and TOF for ultrasound propagating in both transverse and diametral planes of liquid-solid single crystal (Ge) bodies was reported. Numerical simulations indicated that the magnitude and direction of the group velocity, the solid:liquid velocity ratio and the curvature of the interface together controlled the ray bending behavior and thus determined the ultrasonic data across the interface. Knowledge of ray paths at the interface enabled reconstruction of the interface using a small set of ultrasonic TOF’s

Ultrasonic Evaluation of in-Plane and out-of-Plane Elastic Properties of Composite Materials

Evaluation of elastic properties of composite materials using ultrasound is important for the generation of output data for the design of composites. It is also extremely important as a nondestructive tool for quality evaluation of the composites after manufacturing. The problem was addressed in the seventies [1–3] when Markham [1] suggested using the time-delay through transmission technique with obliquely incident ultrasonic waves from water onto a composite plate. The full set of elastic constants was measured later by Kriz and Stinchcomb [4] on samples cut out in different directions from a composite plate. Recently several works have appeared where the set of elastic constants was measured by using Markham’s technique [5–7]

Streptococcus uberis strains isolated from the bovine mammary gland evade immune recognition by mammary epithelial cells, but not of macrophages

Streptococcus uberis is frequently isolated from the mammary gland of dairy cattle. Infection with some strains can induce mild subclinical inflammation whilst others induce severe inflammation and clinical mastitis. We compared here the inflammatory response of primary cultures of bovine mammary epithelial cells (pbMEC) towards S. uberis strains collected from clinical or subclinical cases (seven strains each) of mastitis with the strong response elicited by Escherichia coli. Neither heat inactivated nor live S. uberis induced the expression of 10 key immune genes (including TNF, IL1B, IL6). The widely used virulent strain 0140J and the avirulent strain, EF20 elicited similar responses; as did mutants defective in capsule (hasA) or biofilm formation (sub0538 and sub0539). Streptococcus uberis failed to activate NF-κB in pbMEC or TLR2 in HEK293 cells, indicating that S. uberis particles did not induce any TLR-signaling in MEC. However, preparations of lipoteichoic acid (LTA) from two strains strongly induced immune gene expression and activated NF-κB in pbMEC, without the involvement of TLR2. The immune-stimulatory LTA must be arranged in the intact S. uberis such that it is unrecognizable by the relevant pathogen receptors of the MEC. The absence of immune recognition is specific for MEC, since the same S. uberis preparations strongly induced immune gene expression and NF-κB activity in the murine macrophage model cell RAW264.7. Hence, the sluggish immune response of MEC and not of professional immune cells to this pathogen may aid establishment of the often encountered belated and subclinical phenotype of S. uberis mastitis

The Doctor as Fuduciaries: Do Doctors Have the Right Not to Treat

Composite structures are often desirable for their strength and weight characteristics. Since composites are not as well characterized mechanically as metallic or ceramic structures, much work has been performed to obtain that characterization and to develop methods of determining the mechanical properties of a composite nondestructively. Most of the work in the literature to date has been performed on nonenclosed structures on which several promising nondestructive evaluation (NDE) techniques have been used to predict the integrity of the composite.1,4 An increased use of composites in enclosed geometries has led to the desire to transfer and further develop the most promising NDE techniques used on nonenclosed geometries to enclosed geometries.5,6 As part of the further development of ultrasonic inspection techniques, a high-speed data-acquisition system has been assembled which digitizes an entire RF signal waveform at each point on a Kevlar-epoxy composite structure. The complete data set of ultrasonic A-scans is then available for analysis of particular features which might ordinarily have been overlooked when only the maximum amplitude is recorded from data in a preset gate. The system provides a three-dimensional view of the data in which either the XY, YZ, or XZ planes can be displayed using pseudo color or gray scale to indicate the maximum signal amplitude in a gate set under program control. Depth information can be displayed on the XY data plane, and various image display techniques can be implemented to enhance certain material or defect conditions

Cleft lip and palate - team approach to management

For quite some time, the use of ultrasonic sensors for the application of monitoring the polymer curing process has been explored [1–4]. For the most part, these studies have confined themselves to the monitoring of the curing of a neat resin (without fibers), utilizing normally incident longitudinal or shear plane waves. This approach does not account for the anisotropy associated with composites, nor does it allow for the generation of alternative wave types