This study reports on monthly scans of healthy patient volunteers with the clinical prototype of a microwave imaging system. The system uses time-domain measurements, and incorporates a multistatic ...radar approach to imaging. It operates in the 2-4 GHz range and contains 16 wideband sensors embedded in a hemispherical dielectric radome. The system has been previously tested on tissue phantoms in controlled experiments. With this system prototype, we scanned 13 patients (26 breasts) over an eight-month period, collecting a total of 342 breast scans. The goal of the study described in this paper was to investigate how the system measurements are impacted by multiple factors that are unavoidable in monthly monitoring of human subjects. These factors include both biological variability (e.g., tissue variations due to hormonal changes or weight gain) and measurement variability (e.g., inconsistencies in patient positioning, system noise). For each patient breast, we process the results of the monthly scans to assess the variability in both the raw measured signals and in the generated images. The significance of this study is that it quantifies how much variability should be anticipated when conducting microwave breast imaging of a healthy patient over a longer period. This is an important step toward establishing the feasibility of the microwave radar imaging system for frequent monitoring of breast health.
Flexible 16 Antenna Array for Microwave Breast Cancer Detection Bahramiabarghouei, Hadi; Porter, Emily; Santorelli, Adam ...
IEEE transactions on biomedical engineering,
2015-Oct., 2015-Oct, 2015-10-00, 20151001, Letnik:
62, Številka:
10
Journal Article
Recenzirano
Radar-based microwave imaging has been widely studied for breast cancer detection in recent times. Sensing dielectric property differences of tissues has been studied over a wide frequency band for ...this application. We design single- and dual-polarization antennas for wireless ultrawideband breast cancer detection systems using an inhomogeneous multilayer model of the human breast. Antennas made from flexible materials are more easily adapted to wearable applications. Miniaturized flexible monopole and spiral antennas on a 50-μm Kapton polyimide are designed, using a high-frequency structure simulator, to be in contact with biological breast tissues. The proposed antennas are designed to operate in a frequency range of 2-4 GHz (with reflection coefficient (S11) below -10 dB). Measurements show that the flexible antennas have good impedance matching when in different positions with different curvature around the breast. Our miniaturized flexible antennas are 20 mm × 20 mm. Furthermore, two flexible conformal 4 × 4 ultrawideband antenna arrays (single and dual polarization), in a format similar to that of a bra, were developed for a radar-based breast cancer detection system. By using a reflector for the arrays, the penetration of the propagated electromagnetic waves from the antennas into the breast can be improved by factors of 3.3 and 2.6, respectively.
Considerable exploration has been done in recent years to exploit the reported inherent dielectric contrast between healthy and malignant tissues for a range of medical applications. In particular, ...microwave technologies have been investigated towards new diagnostic medical tools. To assess the performance and detection capabilities of such systems, tissue-mimicking phantoms are designed for controlled laboratory experiments. We here report phantoms developed to dielectrically represent malign skin lesions such as liposarcoma and nonsyndromic multiple basal cell carcinoma. Further, in order to provide a range of anatomically realistic scenarios, and provide meaningful comparison between different phantoms, cancer-mimicking lesions are inserted into two different types of skin phantoms with varying tumor-skin geometries. These configurations were measured with a microwave dielectric probe (0.5-26.5 GHz), yielding insight into factors that could affect the performance of diagnostic and detection tools.
Nowadays, the usage of social media has become integral part of life for many generations. These Web-based tools have allowed tourism companies to identify tourists ' needs and keep up with ...ever-changing market. Thus, this research paper presents the application of social media in tourism marketing, which extend tourism boundaries in innovative way. In this regard, the subject of the paper is to determine if social media have positive impact on business performances in tourism sector and how to incorporate these tools in tourism brand strategies. The paper is based on secondary data, gathered from academic publications from different scientific fields: tourism, marketing and IT. Research results confirmed the primary hypotheses, which indicated that social media have positive impact on tourists 'purchase intentions and brand loyalty, through which business performances of tourism companies have been improved The significance of the research results is reflected as the optimization of social media usage in tourism marketing in order to improve the quality of tourism services and tourists 'satisfaction.
Candidate selection has a direct impact on the quality of a company's human resources department, so it's an essential activity for public and private companies alike. Various ways have been created ...to assist and make it easier for organizations to select the best candidate, specifically the right people to do specific roles. As a result, the purpose of this study is to propose the use of multi-criteria decision-making techniques in personnel selection. Therefore, for the determination of the weights of the criteria will be employed the SWARA method, whereas, for the ranking of the alternatives, i.e. selection of the best candidate, a CoCoSo method will be applied.
In conventional time-domain ultra-wide band (UWB) imaging in the GHz-range, the received signal is sampled and digitized at a very high rate of tens of GHz. This complicates the imaging platform and ...increases the costs. Instead of digitizing the full signal in time domain, this paper proposes that only a few peak values of the receiver signal and their corresponding incident-time stamps can be digitized and analyzed, resulting in sufficient information for successful imaging. This reduces the receiver complexity as well as the acquisition time. The proposed technique is implemented as an integrated circuit (IC) in a TSMC 65nm CMOS technology. Consequently, the receiver block only requires the designed receiver IC as well as a microcontroller to digitize the output data of the IC and transfer them to the computer, and thus, it significantly simplifies the receiver block. A tissue-mimicking phantom, consisting of a 10-cm fat cylinder, with a 2mm skin layer and an embedded tumor, is used to experimentally test the feasibility of the noted approach. A localization error of 0.4 cm to 1 cm is achieved using the proposed technique, for tumors, ranging from 0.5 cm to 0.9 cm in diameter. The acquisition time per received signal is 22ms, an order of magnitude less than that of the imaging techniques reported to date.
The challenges in antenna design for microwave-based breast screening systems identify two distinct needs: 1) to minimize the surface-wave propagation at the interface between the substrate and the ...tissue, and 2) to address the back-radiation. These surface waves become more noticeable within the substrate, particularly when a confining ground plane is present, and yet the ground plane is pivotal for achieving unidirectionality and shielding against environmental radiation. This paper introduces a simplified human breast model and offers a quantitative analysis of existing surface waves. We then propose a 16-antenna array of cavity-backed patch antennas with parasitic elements, designed for operation in the 3.1-5.1 GHz range. Each antenna element is optimized to function seamlessly alongside the breast tissue. Full-wave simulations illustrate that the proposed antenna array achieves superior unidirectionality and diminished mutual coupling levels when compared to its predecessor. We further outline the cost-effective fabrication method that employs the SYLGARD(TM) 184 silicone elastomer PDMS kit. The measurements from the fabricated antenna elements are consistent with the results of the full-wave simulations.
In this study, we compared affective ratings of emotional valence and arousal for 882 Serbian words at three points in time: before the onset of the COVID-19 pandemic (2018), during the COVID-19 ...lockdown (2020), and after the government measures were abandoned (2022). We did not observe a significant change in average valence or arousal ratings across time points. A more detailed look into the data revealed the change in arousal that was different across the valence values. An increase in their linear correlations and a decrease in the nonlinearity of the GAMM smooth demonstrated that, upon the onset of the COVID-19 pandemic, emotionally negative words elicited higher arousal ratings, whereas emotionally positive words elicited lower arousal ratings. It revealed that our participants became more sensitive to the negative content and less sensitive to the positive content. Our results add to the findings, which showed that the relationship between emotional valence and arousal is a function of contextual factors, which primarily influence the arousal of words.
Melatonin (MLT), earlier described as an effective anti-inflammatory agent, could be a beneficial adjunctive drug for sepsis treatment. This study aimed to determine the effects of MLT application in ...lipopolysaccharide (LPS)-induced sepsis in Wistar rats by determining the levels of liver tissue pro-inflammatory cytokines (TNF-α, IL-6) and NF-κB as well as hematological parameters indicating the state of sepsis. Additionally, an immunohistological analysis of CD14 molecule expression was conducted. Our research demonstrated that treatment with MLT prevented an LPS-induced increase in pro-inflammatory cytokines TNF-α and IL-6 and NF-κB levels, and in the neutrophil to lymphocyte ratio (NLR). On the other hand, MLT prevented a decrease in the blood lymphocyte number induced by LPS administration. Also, treatment with MLT decreased the liver tissue expression of the CD14 molecule observed after sepsis induction. In summary, in rats with LPS-induced sepsis, MLT was shown to be a significant anti-inflammatory agent with the potential to change the liver's immunological marker expression, thus ameliorating liver function.
Oxidoreductase (OXR) enzymes are in high demand for biocatalytic applications in the food industry and cosmetics (glucose oxidase (GOx) and cellobiose dehydrogenase (CDH)), bioremediations ...(horseradish peroxidase (HRP) and laccase (LAC)), and medicine for biosensors and miniature biofuel cells (GOx, CDH, LAC, and HRP). They can be used in a soluble form and/or within the yeast cell walls expressed as chimeras on the surface of yeast cells (YSD), such as P. pastoris and S. cerevisiae. However, most of the current studies suffer from either low yield for soluble enzyme expression or low enzyme activity when expressed as chimeric proteins using YSD. This is always the case in studies dealing with the heterologous expression of oxidoreductase enzymes, since there is a requirement not only for multiple OXR gene integrations into the yeast genome (super transformations), and codon optimization, but also very careful design of fermentation media composition and fermentation conditions during expression due to the need for transition metals (copper and iron) and metabolic precursors of FAD and heme. Therefore, scientists are still trying to find the optimal formula using the above-mentioned approaches; most recently, researcher started using protein engineering and directed evolution to increase in the yield of recombinant enzyme production. In this review article, we will cover all the current state-of-the-art technologies and most recent advances in the field that yielded a high expression level for some of these enzymes in specially designed expression/fermentation systems. We will also tackle and discuss new possibilities for further increases in fermentation yield using cutting-edge technologies such as directed evolution, protein and strain engineering, high-throughput screening methods based on in vitro compartmentalization, flow cytometry, and microfluidics.
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