Semiconductor cooling by thin-film thermocouples

Thin-film, metal alloy thermocouple junctions do not rectify, change circuit impedance only slightly, and require very little increase in space. Although they are less efficient cooling devices than semiconductor junctions, they may be applied to assist conventional cooling techniques for electronic devices

Books You Might Like

(BOOKS & COKES, sponsored by SKETCH, presents regular weekly studentplanned, student-presented book reviews in the Oak Room, Memorial Union, throughout fall and spring quarters. Supplementing that program, here is an ambitious study of the great Naturalist philosopher, regarded as \u27the father of the French Revolution, romanticism, democracy, anarchism, republicanism, communism, and fascism\u27; and, after 150 years, profoundly influential today.)..

Bayesian approach to image reconstruction in photoacoustic tomography

Photoacoustic tomography is a hybrid imaging method that has a variety of biomedical applications. In photoacoustic tomography, the image reconstruction problem (inverse problem) is to resolve the initial pressure distribution from detected ultrasound waves generated within an object due to an illumination of a short light pulse. In this work, this problem is approached in Bayesian framework. Image reconstruction is investigated with numerical simulations in different detector geometries, including limited view setup, and utilizing different prior information. Furthermore, assessing the reliability of the estimates is investigated. The simulations show that the Bayesian approach can produce accurate estimates of the initial pressure distribution and uncertainty information even in a limited view setup if proper prior information is utilized

Modelling of errors due to speed of sound variations in photoacoustic tomography using a Bayesian framework

Inverse problem of estimating initial pressure in photoacoustic tomography is ill-posed and thus sensitive to errors in modelling and measurements. In practical experiments, accurate knowledge of the speed of sound of the imaged target is commonly not available, and therefore an approximate speed of sound is used in the computational model. This can result in errors in the solution of the inverse problem that can appear as artefacts in the reconstructed images. In this paper, the inverse problem of photoacoustic tomography is approached in a Bayesian framework. Errors due to uncertainties in the speed of sound are modelled using Bayesian approximation error modelling. Estimation of the initial pressure distribution together with information on the reliability of these estimates are considered. The approach was studied using numerical simulations. The results show that uncertainties in the speed of sound can cause significant errors in the solution of the inverse problem. However, modelling of these uncertainties improves the accuracy of the solution

Modelling of errors and uncertainties in photoacoustic tomography using a Bayesian framework

Photoacoustic tomography is studied in the framework of Bayesian inverse problems. Modelling of errors and uncertainties using Bayesian approximation error modelling is investigated. The approach is tested with simulation

Black Mesoporous Silicon as a Contrast Agent for LED-Based 3D Photoacoustic Tomography

Mesoporous silicon (PSi) nanoparticles have been widely studied in different biomedical imaging modalities due to their several beneficial material properties. However, they have not been found to be suitable for photoacoustic imaging due to their poor photothermal conversion performance. In the present study, biodegradable black mesoporous silicon (BPSi) nanoparticles with strong light absorbance were developed as superior image contrast agents for photoacoustic tomography (PAT), which was realized with a light-emitting diode (LED) instead of the commonly used laser. LED-based PAT offers the advantages of low cost, compactness, good mobility, and easy operation as compared to the traditional laser-based PAT modality. Nevertheless, the poor imaging sensitivity of the LED-PAT systems has been the main barrier to prevent their wide biomedical application because the LED light has low optical energy. The present study demonstrated that the imaging sensitivity of the LED-PAT system was significantly enhanced with the PEGylated BPSi (PEG–BPSi) nanoparticles. The PEG–BPSi nanoparticles were clearly detectable with a low concentration of 0.05 mg/mL in vitro and with an LED radiation energy of 5.2 μJ. The required concentration of the PEG–BPSi nanoparticles was 10 times lesser than that of the reference gold nanoparticles to reach the corresponding level of the imaging contrast. The ex vivo studies demonstrated that the submillimeter BPSi nanoparticle-based absorbers were distinguishable in chicken breast tissues. The strong contrast provided by the BPSi particles indicated that these particles can be utilized as novel contrast agents in PAT, especially in LED-based systems with low light intensity

Comparing Three Countries’ Higher Education Students’ Cyber Related Perceptions and Behaviours during COVID-19

In 2020, a global pandemic led to lockdowns, and subsequent social and business restrictions. These required overnight implementation of emergency measures to permit continued functioning of vital industries. Digital technologies and platforms made this switch feasible, but it also introduced several cyber related vulnerabilities, which students might not have known how to mitigate. For this study, the Global Cyber Security Index and the Cyber Risk literacy and education index were used to provide a cyber security context for each country. This research project—an international, cross-university, comparative, quantitative project—aimed to explore the risk attitudes and concerns, as well as protective behaviours adopted by, students at a South African, a Welsh and a Hungarian University, during the pandemic. This study’s findings align with the relative rankings of the Oliver Wyman Risk Literacy and Education Index for the countries in which the universities reside. This study revealed significant differences between the student behaviours of students within these universities. The most important differences were identified between students’ risk attitudes and concerns. It was also discovered that South African students reported having changed their protective online behaviours to the greatest extent, since the pandemic commenced. Recommendations are made suggesting that cyber security training and education, as well as improving the digital trust and confidence in digital platforms, are critical

Higher Education Students’ Perceptions of Online Learning during COVID-19—A Comparative Study

The pandemic and subsequent ‘lockdown’ has dramatically changed the educational landscape of higher education institutions. Pre-covid-19, traditional universities had choices in pedagogical practice, which included a variety of teaching delivery modes. Overnight, a single mode of delivery became the only option for traditional higher education institutions. All services had to be migrated to digital platforms, leading to a period of “emergency eLearning”. The full impact of this sudden shift to digital platforms on all cohorts of students is still uncertain. A measure of disruption to the normal student learning experience, especially for those attending traditional universities, was inevitable. Moreover, this disruption was varied depending on the University’s country and the country’s lockdown rules. This international, comparative, quantitative research project aimed to investigate and understand the higher education students’ perceptions of emergency eLearning during the first wave of COVID-19. Experiences of students at universities in three countries were evaluated in terms of four dimensions: 1) home learning environment, 2) engagement, 3) participation preference, and 4) impact on learning skills. The research revealed significant differences between the participating universities. The most important differences were in the ‘home learning environment’, followed by ‘engagement’ and the perception of ‘impact on learning skills’. The differences in the ‘home learning environment’ can be attributed to the differing economic and digital development of the surveyed countries: South Africa, Wales, and Hungary. Finally, different cultural backgrounds suggest a noticeable difference in student engagement, participation, and learning skills

Photoacoustic image reconstruction with uncertainty quantification

Photoacoustic tomography is a hybrid imaging technique that has various applications in biomedicine. In a photoacoustic image reconstruction problem (inverse problem), an initial pressure distribution is reconstructed from measured ultrasound waves which are generated by the photoacoustic effect induced by an optical excitation. In this work, the image reconstruction problem is approached in the framework of Bayesian inversion. The approach is tested with three dimensional numerical simulations. The initial pressure distribution is reconstructed in full-view and limited-view setups. In addition, the reliability of the obtained estimates is assessed. The numerical studies show that accurate estimates of the initial pressure distribution and uncertainty information can be obtained utilizing Bayesian approach