Numerical 3D modeling of heat transfer in human tissues for microwave radiometry monitoring of Brown fat metabolismo

Background: Brown adipose tissue (BAT) plays an important role in whole body metabolism and could potentially mediate weight gain and insulin sensitivity. Although some imaging techniques allow BAT detection, there are currently no viable methods for continuous acquisition of BAT energy expenditure. We present a non-invasive technique for long term monitoring of BAT metabolism using microwave radiometry. Methods: A multilayer 3D computational model was created in HFSS™ with 1.5 mm skin, 3-10 mm subcutaneous fat, 200 mm muscle and a BAT region (2-6 cm3) located between fat and muscle. Based on this model, a log-spiral antenna was designed and optimized to maximize reception of thermal emissions from the target (BAT). The power absorption patterns calculated in HFSS™ were combined with simulated thermal distributions computed in COMSOL® to predict radiometric signal measured from an ultra-low-noise microwave radiometer. The power received by the antenna was characterized as a function of different levels of BAT metabolism under cold and noradrenergic stimulation. Results: The optimized frequency band was 1.5-2.2 GHz, with averaged antenna efficiency of 19%. The simulated power received by the radiometric antenna increased 2-9 mdBm (noradrenergic stimulus) and 4-15 mdBm (cold stimulus) corresponding to increased 15-fold BAT metabolism. Conclusions: Results demonstrated the ability to detect thermal radiation from small volumes (2-6 cm3) of BAT located up to 12 mm deep and to monitor small changes (0.5°C) in BAT metabolism. As such, the developed miniature radiometric antenna sensor appears suitable for non-invasive long term monitoring of BAT metabolism

A Novel Compact Microwave Radiometric Sensor to Noninvasively Track Deep Tissue Thermal Profiles

Drawing from space technology to measure star temperature, we developed a noninvasive sensor to passively track thermal profiles in tissues well below the skin (\u3e5cm). Ultra-low noise amplifiers combined with ultralow-loss switches in the 1- 2GHz band produce a high sensitivity multiband microwave radiometer. Due to the complex multilayer anatomy of human head, multiple sensing bands are needed to reconstruct the temperature of deep brain tissue. This is achieved by using a digitally controlled filter bank. To study its accuracy, the sensor was calibrated and tested in a multilayer phantom model of the human head with differential scalp and brain temperatures. Results of phantom testing showed that calculated radiometric equivalent brain temperature agreed within 0.4°C of measured temperature when circulating homogenized brain phantom was lowered 10°C and returned to original temperature (37°C), while scalp was maintained constant over a 4.6-hour experiment. Feasibility of clinical monitoring was assessed in a pediatric patient during a hypothermic heart surgery. Over the 2-hour surgery, the radiometric sensor tracked within 1°C of rectal and nasopharynx temperatures, except during rapid cooldown and heatup periods when brain temperature deviated 2-4°C from slower responding core temperature surrogates. In summary, the sensor demonstrated long term stability and sensitivity sufficient for accurate monitoring of volume average brain temperatur

The global burden of adolescent and young adult cancer in 2019 : a systematic analysis for the Global Burden of Disease Study 2019

Background In estimating the global burden of cancer, adolescents and young adults with cancer are often overlooked, despite being a distinct subgroup with unique epidemiology, clinical care needs, and societal impact. Comprehensive estimates of the global cancer burden in adolescents and young adults (aged 15-39 years) are lacking. To address this gap, we analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, with a focus on the outcome of disability-adjusted life-years (DALYs), to inform global cancer control measures in adolescents and young adults. Methods Using the GBD 2019 methodology, international mortality data were collected from vital registration systems, verbal autopsies, and population-based cancer registry inputs modelled with mortality-to-incidence ratios (MIRs). Incidence was computed with mortality estimates and corresponding MIRs. Prevalence estimates were calculated using modelled survival and multiplied by disability weights to obtain years lived with disability (YLDs). Years of life lost (YLLs) were calculated as age-specific cancer deaths multiplied by the standard life expectancy at the age of death. The main outcome was DALYs (the sum of YLLs and YLDs). Estimates were presented globally and by Socio-demographic Index (SDI) quintiles (countries ranked and divided into five equal SDI groups), and all estimates were presented with corresponding 95% uncertainty intervals (UIs). For this analysis, we used the age range of 15-39 years to define adolescents and young adults. Findings There were 1.19 million (95% UI 1.11-1.28) incident cancer cases and 396 000 (370 000-425 000) deaths due to cancer among people aged 15-39 years worldwide in 2019. The highest age-standardised incidence rates occurred in high SDI (59.6 [54.5-65.7] per 100 000 person-years) and high-middle SDI countries (53.2 [48.8-57.9] per 100 000 person-years), while the highest age-standardised mortality rates were in low-middle SDI (14.2 [12.9-15.6] per 100 000 person-years) and middle SDI (13.6 [12.6-14.8] per 100 000 person-years) countries. In 2019, adolescent and young adult cancers contributed 23.5 million (21.9-25.2) DALYs to the global burden of disease, of which 2.7% (1.9-3.6) came from YLDs and 97.3% (96.4-98.1) from YLLs. Cancer was the fourth leading cause of death and tenth leading cause of DALYs in adolescents and young adults globally. Interpretation Adolescent and young adult cancers contributed substantially to the overall adolescent and young adult disease burden globally in 2019. These results provide new insights into the distribution and magnitude of the adolescent and young adult cancer burden around the world. With notable differences observed across SDI settings, these estimates can inform global and country-level cancer control efforts. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.Peer reviewe

Target-Specific Microwave Antenna Optimization for Pre-Clinical and Clinical Bladder Hyperthermia Devices

<p>We have yet to establish the optimum combination of hyperthermia with radiation and/or chemotherapy for effective treatment of bladder cancer. Convenient and affordable microwave applicators capable of well-localized non-invasive heating of murine, canine and human bladder cancers is essential for logical progression of studies from pre-clinical to multi-institution clinical trials, as needed to investigate the effects of hyperthermia as an adjuvant treatment for bladder cancer. </p><p>The primary objective of this research was to utilize state-of-the art segmentation and simulation software to optimize target-specific microwave antennas for more uniform heating in pre-clinical and clinical investigations of bladder hyperthermia.</p><p>The results of this research are:</p><p>1. The development of a reliable simulation-based approach for optimizing microwave applicators;</p><p>2. The design, construction and testing of an applicator for heating murine bladder to 40-43°C while maintaining surface and core temperatures normothermic;</p><p>3. The optimization, construction and testing of a fundamentally different type of antenna (metamaterial) for heating pediatric and/or canine bladder;</p><p>4. A preliminary effort towards the optimization, construction and testing of a metamaterial antennas for heating adult bladder.</p><p>One significant implication of this work is to enable essential pre-clinical bladder hyperthermia studies with the development of a reliable microwave applicator for heating murine bladder to 40-43°C while maintaining surface and core temperatures normothermic. It is clear that hyperthermia enhances the effects of chemo- and radio- therapies, and this device will allow scientists to investigate the basic principles underlying this phenomenon more systematically.</p><p>Another significant contribution of this work is the development of metamaterial antennas for deep tissue hyperthermia. These antennas decrease the cost and increase the comfort and portability of bladder hyperthermia devices. These improvements will enable the multi-institutional clinical trials required to apply for insurance reimbursement of deep-tissue thermal therapy and the subsequent widespread use of hyperthermia as an adjuvant to current cancer therapies.</p>Dissertatio

Automated process and geometry design optimization of a coal combustion reactor

The importance of design of an optimized and efficient combustion or gasification system, the complexity of such an optimization problem with conflicting objectives and the inadequacy of traditional optimization methods in searching the entire design space and their random nature, presents the significant importance of proposing an automated multi-objective optimization method in the field of combustion and gasification design. In the current research, automated multi-objective optimization has been implemented in geometry and process design of a coal combustion reactor. Coal particles are mixed with air and are injected into the reactor via four tangential inlets to create swirl flow. A combination of single phase and multi-phase reactions has been considered to simulate the combustion process. All the steps of geometry creation, grid generation and CFD simulation have been integrated automatically using macro files to run in batch mode in an optimization platform, i.e., modeFrontier. Three multi-objective optimization problems have been solved with two, four and six input variables. The ε-constraint method has been implemented for multi-objective optimization. Each multi-objective optimization problem consists of individual single-objective optimization problems which are solved by the SIMPLEX method. Two conflicting objectives, i.e., NO mass fraction and CH4 mass fraction, have been selected for all optimization problems. Results from all single objective optimizations have been summarized to obtain the Pareto Set. It is presented that automated multi-objective optimization is a reliable and promising method to integrate CAD and CFD tools with optimization methods in an automated process to perform faster, more accurate, more efficient and more cost-effective designs in the field of combustion and gasification.Ph. D.Includes bibliographical referencesby Sara Salah

Design and optimization of na ultra wideband and compact microwave antenna for radiometric monitoring of brain temperature

We present the modeling efforts on antenna design and frequency selection to monitor brain temperature during prolonged surgery using noninvasive microwave radiometry. A tapered log-spiral antenna design is chosen for its wideband characteristics that allow higher power collection from deep brain. Parametric analysis with the software HFSS is used to optimize antenna performance for deep brain temperature sensing. Radiometric antenna efficiency (eta) is evaluated in terms of the ratio of power collected from brain to total power received by the antenna. Anatomical information extracted from several adult computed tomography scans is used to establish design parameters for constructing an accurate layered 3-D tissue phantom. This head phantom includes separate brain and scalp regions, with tissue equivalent liquids circulating at independent temperatures on either side of an intact skull. The optimized frequency band is 1.1-1.6 GHz producing an average antenna efficiency of 50.3% from a two turn log-spiral antenna. The entire sensor package is contained in a lightweight and low-profile 2.8 cm diameter by 1.5 cm high assembly that can be held in place over the skin with an electromagnetic interference shielding adhesive patch. The calculated radiometric equivalent brain temperature tracks within 0.4 degrees C of the measured brain phantom temperature when the brain phantom is lowered 10. C and then returned to the original temperature (37 degrees C) over a 4.6-h experiment. The numerical and experimental results demonstrate that the optimized 2.5-cm log-spiral antenna is well suited for the noninvasive radiometric sensing of deep brain temperature

The burden of metabolic risk factors in North Africa and the Middle East, 1990–2019: findings from the Global Burden of Disease StudyResearch in context

Summary: Background: The objective of this study is to investigate the trends of exposure and burden attributable to the four main metabolic risk factors, including high systolic blood pressure (SBP), high fasting plasma glucose (FPG), high body-mass index (BMI), and high low-density lipoproteins cholesterol (LDL) in North Africa and the Middle East from 1990 to 2019. Methods: The data were retrieved from Global Burden of Disease Study 2019. Summary exposure value (SEV) was used for risk factor exposure. Burden attributable to each risk factor was incorporated in the population attributable fraction to estimate the total attributable deaths and disability-adjusted life-years (DALYs). Findings: While age-standardized death rate (ASDR) attributable to high-LDL and high-SBP decreased by 26.5% (18.6–35.2) and 23.4% (15.9–31.5) over 1990–2019, respectively, high-BMI with 5.1% (−9.0–25.9) and high-FPG with 21.4% (7.0–37.4) change, grew in ASDR. Moreover, age-standardized DALY rate attributed to high-LDL and high-SBP declined by 30.2% (20.9–39.0) and 25.2% (16.8–33.9), respectively. The attributable age-standardized DALY rate of high-BMI with 8.3% (−6.5–28.8) and high-FPG with 27.0% (14.3–40.8) increase, had a growing trend. Age-standardized SEVs of high-FPG, high-BMI, high-SBP, and high-LDL increased by 92.4% (82.8–103.3), 76.0% (58.9–99.3), 10.4% (3.8–18.0), and 5.5% (4.3–7.1), respectively. Interpretation: The burden attributed to high-SBP and high-LDL decreased during the 1990–2019 period in the region, while the attributable burden of high-FPG and high-BMI increased. Alarmingly, exposure to all four risk factors increased in the past three decades. There has been significant heterogeneity among the countries in the region regarding the trends of exposure and attributable burden. Urgent action is required at the individual, community, and national levels in terms of introducing effective strategies for prevention and treatment that account for local and socioeconomic factors. Funding: Bill &amp; Melinda Gates Foundation