A Hybrid Microwave-Optical Applicator for Local Muscle Warming and Monitoring

Local warming of human tissue causes vasodilation and therefore blood volume to increase. Such thermal blood volume response allows the assessment of microcirculation in tissue, providing clinically important information. The deep warming is provided by a novel microwave applicator, which has a annular-ring microstrip patch operating at 2450 MHz with a superstrate interface layer to improve the coupling of electromagnetic (EM) waves into the skin. The design is based on computer simulations of specific absorption rate (SAR) and thermal distribution of the EM waves in a biological medium. The simulation results show that the applicator can elevate the muscle temperature by 3 to 4^{\circ}\mathrm{C}. The thermal response is measured by an integrated optical probe which measures tissue oxygenation changes in deep tissue using the near infrared spectroscopy technique

Development of a hybrid microwave-optical system to monitor human thermoregulation

Warming of human tissue causes vasodilation and therefore, increase in blood volume. Such thermal responses allow the assessment of hemodynamics in the tissue, providing physiological and clinically important information of the diagnosed subject. Local warming is often accomplished on the skin because of its accessibility and simplicity. To allow the investigation into deeper tissue such as the muscle, an innovative hybrid microwave-optical system has been developed. This comprises of a microwave system, an optical monitoring and cooling system. The tissue warming is induced by a novel microwave applicator, which was based on microstrip patch design operating at 2.45 GHz with a superstrate interface layer to improve the coupling of electromagnetic (EM) waves into the skin. The active cooling was introduced to reduce skin heating. While the optical sensors based on Near-Infrared Spectroscopy (NIRS), was used to measure the changes in tissue oxygenation including the muscle. This thesis demonstrates the development procedure, covering the design and operation of the entire system. Moreover, the majority of the work is based on the four developed applicators, where each design was evaluated using EM and thermal simulation based on numerical phantoms. The study evaluates the distribution of absorbed EM energy in the tissue known as the specific absorption rate (SAR). The applicators are developed in the following order: (i) Applicator I was fabricated for preliminary study for general tissue heating with the integrated optical probes. This early study provided an insight to the importance of superstrate thickness and material. (ii) Applicator II, which introduces a new approach to skin cooling based on Thermoelectric Coolers (TEC) and high thermal conductive superstrate. This design could cool the skin and monitor tissue oxygenation, skin perfusion and temperature. (iii) Applicator III was an updated model of the predecessor, resolving cooling configuration and the discrepancy in operating frequency, and was capable of minimising skin heating effectively (iv) Circularly polarized (CP) Applicator aimed at reduction of the SAR in the superficial layer, and hence skin heating. The simulated thermal study of all developed applicators was validated with exvivo (mimicked phantom) and in-vivo experimental trials. The measurements and the simulation model were in agreement, apart from the CP applicator due to the complexity of measurement. The results from the phantom and human calf indicated superficial heating was reduced by about 5.0-6.0 ° C when skin cooling was applied, while the temperature change in muscle was not significantly affected. The measurement with mimicked tissue showed the applicator was capable of elevating muscle temperature by approximately 3.0-4.0 ° C. This is a sufficient increase to cause tissue dilation, and therefore, change in the thermal response. The hybrid microwave-optical system has been developed and examined on three human calves during in-vivo physiological study. The results using Applicator II illustrated that the device can successfully stimulate and measure thermal responses in terms of oxy/deoxy/total haemoglobin concentrations changes ( HbO2/ HHb/ HbT). The slope (rate of change) of HbT curve during microwave exposure is defined as the thermal response. This parameter is essential in studying physiological responses between different subject, particularly in vascular diseases, transplanted free flaps and other conditions, including chronic spinal cord injury. Subjects with such conditions will have a distinguishable response to tissue heating than a healthy subject. The monitored haemodynamic signals of Applicator II are primarily based on superficial responses. However, measurements with Applicator III showed the potential of the applicator. The measured thermal response was 0.83 10 3×10⁻³ μM/s without skin cooling, which was dedicated by skin heating. The introduced cooling system has reduced the skin temperature and maintained the local skin micro-circulation, which was monitored with the secondary optical system based on Laser Doppler Flowmetry (LDF). This probe measures blood flow at superficial depth, and consequently, was used as a validation tool to demonstrate the cooling efficiency. The measured thermal response with skin over-cooling was -0.08 10 3×10⁻³ μM/s. The negative response indicates arterial constriction, and therefore, the skin heat was eliminated while the simulations study to indicate the muscle temperature was elevated by 3 ° C. However, the response was dominant by the superficial response. Obtaining a response from muscle only was challenging and currently being solved in numerous applicator and cooling technique, which have been presented in the thesis

A feasibility study of elastography based confocal microwave imaging technique for breast cancer detection

Breast cancer is a common cancer type in women and its death rate is second highest among different kind of cancers. Early detection is an efficient way for curing and recovery. Confocal microwave imaging (CMI) using electromagnetic method for detection of breast cancer can avoid ionization caused by mammography. CMI uses the contrast of electrical properties between tumor and normal breast tissue to identify the existence and location of the tumor. However, new research result shows that gland and tumor have similar dielectric constant and electrical conductivity, so it is hard to distinguish gland and tumor. This paper proposes a new method based on elastography for the tumor identification. The high Young's modulus contrast of the two tissues resulting in different level of deformation by compression will provide sufficient features to discriminate whether the reflected signal is belonged to gland or tumor. Finite-difference time-domain (FDTD) method was used in simulation. Some examples were presented to validate the identification

A Dual-Band Dual-Polarization Slot Patch Antenna for GPS and Wi-Fi Applications

In this letter, a dual-band and dual-polarization capacitive-fed slot patch antenna is investigated. The proposed antenna can operate at 1.575 GHz for Global Positioning System and 2.4 GHz for Wi-Fi system with the corresponding polarizations. A 90 ° hybrid coupler chip was used to excite the right-hand circular polarization required for optimum GPS performance. For the high frequency band, a pair of linearly polarized arc-shaped slots radiating at 2.4 GHz are embedded in the circular patch. The operating bandwidths of the antenna are enhanced by the multilayered geometry, and the capacitive disks feedpoints placed between the substrate layers. The measured impedance bandwidths at the lower and high bands are 320 and 230 MHz, respectively. The measured 3-dB axial-ratio bandwidth is 120 MHz

A dual band dual polarization slot patch antenna

A dual band and dual polarization slot patch antenna for Global Positioning System (GPS) and wireless LAN network with the corresponding polarizations is proposed. An L-shaped slot and a small stub are utilized to excite the desirable right-hand circular polarization (RHCP) for GPS. Meanwhile the linearly polarized electromagnetic wave for Wi-Fi communications at 2.4 GHz is contributed by an arc-shaped slot embedded circular patch. The multi-layered geometry and the capacitive feeding disk placed between the substrate layers enhance the operating bandwidths of the antenna. The achievable percentage bandwidths at the low and high bands are 6.4% and 7% respectively. The measured 3dB axial ratio (AR) bandwidth is 34 MHz, which covers the GPS L1 band

Familial cancer risk in family members and spouses of patients with early-onset head and neck cancer

Background Reported patterns of familial aggregation of head and neck cancer (HNC) vary greatly, with many studies hampered by the limited number of subjects. Methods Altogether 923 early-onset ( Results Of all early-onset HNC families, only 21 (2.3%) had familial HNC cancers at any age and less than five familial early onset HNC cancers among first-degree relatives. The cumulative risk of HNC for siblings by age 60 (0.52%) was at population level (0.33%). No increased familial risk of early-onset HNC could be discerned in family members (SIR 2.68, 95% CI 0.32-9.68 for first-degree relatives). Conclusions Our study indicates that the cumulative and relative familial risk of early-onset HNC is modest in the Finnish population and, at most, only a minor proportion of early-onset HNCs are due solely to inherited genetic mutations.Peer reviewe

Bypass of mutagenic O 6 -Carboxymethylguanine DNA Adducts by Human Y- and B-Family Polymerases

The generation of chemical alkylating agents from nitrosation of glycine and bile acid conjugates in the gastrointestinal tract is hypothesized to initiate carcinogenesis. O6-carboxymethylguanine (O6-CMG) is a product of DNA alkylation derived from nitrosated glycine. Although the tendency of the structurally related adduct O6-methylguanine to code for the misincoporation of TTP during DNA replication is well-established, the impact of the presence of the O6-CMG adduct in a DNA template on the efficiency and fidelity of translesion DNA synthesis (TLS) by human DNA polymerases (Pols) has hitherto not been described. Herein, we characterize the ability of the four human TLS Pols η, ι, κ, and ζ and the replicative Pol δ to bypass O6-CMG in a prevalent mutational hot-spot for colon cancer. The results indicate that Pol η replicates past O6-CMG, incorporating dCMP or dAMP, whereas Pol κ incorporates dCMP only, and Pol ι incorporates primarily dTMP. Additionally, the subsequent extension step was carried out with high efficiency by TLS Pols η, κ, and ζ, while Pol ι was unable to extend from a terminal mismatch. These results provide a first basis of O6-CMG-promoted base misincorporation by Y- and B-family polymerases potentially leading to mutational signatures associated with colon cancer

The radar signature of the Wind Lens: a less disruptive wind turbine?

We study the radar signature of a new type of wind turbine, named the Wind Lens. This design includes a flanged shroud around the turbine which concentrates the wind flow past the turbine blades and hence improves the efficiency. The design also offers improved safety, and reduces acoustic noise. Furthermore, it may offer a significantly lower radar signature, which may make the design much more attractive for use in situations where conventional wind turbine designs may disturb the operation of radars. We present the results of an experimental trial, carried out in the UK, to measure the Radar Cross Section (RCS) of a 5 kW Wind Lens turbine prototype and we provide a reference database that can be used for comparing the Wind Lens RCS with that of conventional turbines. We investigate methods to further reduce the Wind Lens RCS and present the results of a time-varying Doppler analysis. Results show that the addition of a metallic mesh around the shroud obscures the rotating blades, and hence mitigates the RCS by 15 dBm2, at angles where the radar interference is highest