Self-Reconstruction Property of a Special Speckle Pattern after Obstructing by an Opaque Obstruction

Numerical simulation of random optical field with special autocorrelation is performed. It can be seen that the speckle pattern with special autocorrelation is different from the general speckle pattern whose autocorrelation is a Gaussian function. Furthermore, we study the propagation property of the special speckle in free space after blocking by an opaque obstruction and find the self-healing effect of speckle. In particular, we investigate the influence of size and shape of obstruction and the coherence of speckle on the speckle’s reconstruction process. We find that it is affected by the size of obstruction and the coherence of the speckle but is almost not affected by the shape of obstruction. Our results can be applied to the imaging, optical communication, and so on

The perceived impact of the Covid-19 pandemic on medical student education and training – an international survey

Abstract: Background: The Covid-19 pandemic led to significant changes and disruptions to medical education worldwide. We evaluated medical student perceived views on training, their experiences and changes to teaching methods during the pandemic. Methods: An online survey of medical students was conducted in the Autumn of 2020. An international network of collaborators facilitated participant recruitment. Students were surveyed on their perceived overall impact of Covid-19 on their training and several exposure variables. Univariate analyses and adjusted multivariable analysis were performed to determine strengths in associations. Results: A total of 1604 eligible participants from 45 countries took part in this survey and 56.3% (n = 860) of these were female. The median age was 21 (Inter Quartile Range:21–23). Nearly half (49.6%, n = 796) of medical students were in their clinical years. The majority (n = 1356, 84.5%) were residents of a low or middle income country. A total of 1305 (81.4%) participants reported that the Covid-19 pandemic had an overall negative impact on their training. On adjusted analysis, being 21 or younger, females, those reporting a decline in conventional lectures and ward based teaching were more likely to report an overall negative impact on their training (p ≤ 0.001). However, an increase in clinical responsibilities was associated with lower odds of participants reporting a negative impact on training (p < 0.001). The participant’s resident nation economy and stage of training were associated with some of the participant training experiences surveyed (p < 0.05). Conclusion: An international cohort of medical students reported an overall significant negative impact of the Covid-19 pandemic on their undergraduate training. The efficacy of novel virtual methods of teaching to supplement traditional teaching methods warrants further research

Differences in perceived effectiveness of upward dissent strategies between employees and managers.

The way employees communicate dissents in workplaces effectively is one of the keys to successful internal communication. Previous literature on organizational dissents primarily identified different upward dissent strategies and compared the perceived competencies of these strategies only through employees’ self-report. This study, however, compared the perceived effectiveness of upward dissent strategies from both managers’ and employees’ point of views, specifically in Singapore’ context. A survey was conducted among managers and subordinates to investigate if these two groups perceive the effectiveness of dissent strategies differently through a scenario-based questionnaire, where participants were asked to rate how each dissent strategy would bring about a specific desired outcome in that scenario. While managers and employees rated factual appeal and presentation of solution as effective dissent strategies in different scenarios, both groups consistently rated threatening resignation as the weakest strategy. Managers, in particular, rated all dissent strategies higher than employees suggesting that management seemed to take employees’ dissent seriously. These findings provide implications for internal communication that facilitates employees’ dissent.Bachelor of Communication Studie

Flexibly Extensible Planar Self-Isolated Wideband MIMO Antenna for 5G Communications

A planar flexibly extensible multiple-input&ndash;multiple-output (MIMO) antenna array with a self-isolation property is proposed. The main characteristics of the proposed array are: (i) no extra isolation structure is required to improve isolation between elements; (ii) elements are arranged with each other with a spacing of 0 mm, (iii) the configuration can be flexibly extended to a large antenna array according to actual requirements. For a test example, the practical processing and testing of an eight-element array is conducted. The tested results demonstrate that the proposed design possesses wide impedance bandwidth (IBW) of 65% and very good isolation (&gt;18 dB) across the operating bandwidth, which match well with the simulated ones. Moreover, envelope correlation coefficient (ECC) is calculated to valuate MIMO performance; an acceptable ECC (lower than 0.05) suggests that the proposed configuration has good diversity performance and can be a potential candidate for MIMO communications

Sustanable nitrogen managment index: definition, global assessment and potential improvements

To represent the sustainability of nitrogen management in the Sustainable Development Goals indicator framework, this paper proposes a sustainable nitrogen management index (SNMI). This index combines the performance in N crop yield and N use efficiency (NUE), thereby accounting for the need for both food production and environmental protection. Applying SNMI to countries around the world, the results showed improvement in the overall sustainability of crop N management over the past four decades, but this improvement has been mainly achieved by crop yield increase, while global NUE has improved only slightly. SNMI values vary largely among countries, and this variation has increased since the 1970s, implying different levels of success, even failure, in improving N management for countries around the world. In the standard SNMI assessment, the reference NUE was defined as 1.0 (considered an ideal NUE) and the reference yield was defined as 90 kg·ha−1·yr−1 N (considering a globally averaged yield target for meeting food demand in 2050). A sensitivity test that replaced the reference NUE of 1.0 with more realistic NUE targets of 0.8 or 0.9 showed overall reduction in SNMI values (i.e., improved performance), but little change in the ranking among countries. In another test that replaced the universal reference yield with region-specific attainable yield, SNMI values declined (i.e., improved performance) for most countries in Africa and West Asia, whereas they increased for many countries in Europe and South America. The index can be improved by further investigation of approaches for setting region-specific yield targets and high-quality data on crop yield potentials. Overall, SNMI offers promise for a simple and transparent approach to assess progress of countries toward sustainable N management with a single indicato

Enhanced thermal and mechanical performance of 3D architected micro-channel heat exchangers

Many crystals in nature have simple interatomic microstructures, such as simple cubic (SC), body-centered cubic (BCC), and face-centered cubic (FCC) lattice symmetries, making these structures extremely stable. Inspired by these arrangements, a series of architected micro-channel heat exchangers with rationally designed 3D microstructures were established. A multi-physics mathematical model using thermal-fluid-structure interaction (TFSI) was employed to investigate the coupled heat transfer performance and mechanical properties of these architected heat exchangers. When compared with the corrugated straight plate (CSP) microchannel heat exchanger, the thermal-hydraulic performance factors (TPC) of FCC and BCC microchannel heat transfer were 2.20 and 1.70 times that of SC microchannel heat exchanger, respectively. The micro-channel heat exchanger with FCC architectures could enhance the convective heat transfer performance by 201.0%, while the micro-channel heat exchanger with SC architectures reduced the Von-Mises equivalent (VME) stress by 20.0% when compared with the conventional 2D CSP heat exchanger. The proposed architected micro-channel heat exchangers could find a wide range of potential applications ranging from power electronics in electric vehicles to concentrated solar power systems, where both good convective heat transfer performance and high mechanical strength are simultaneously pursued

Short-Term Response of the Soil Microbial Abundances and Enzyme Activities to Experimental Warming in a Boreal Peatland in Northeast China

Global warming is likely to influence the soil microorganisms and enzyme activity and alter the carbon and nitrogen balance of peatland ecosystems. To investigate the difference in sensitivities of carbon and nitrogen cycling microorganisms and enzyme activity to warming, we conducted three-year warming experiments in a boreal peatland. Our findings demonstrated that both mcrA and nirS gene abundance in shallow soil and deep soil exhibited insensitivity to warming, while shallow soil archaea 16S rRNA gene and amoA gene abundance in both shallow soil and deep soil increased under warming. Soil pmoA gene abundance of both layers, bacterial 16S rRNA gene abundance in shallow soil, and nirK gene abundance in deep soil decreased due to warming. The decreases of these gene abundances would be a result of losing labile substrates because of the competitive interactions between aboveground plants and underground soil microorganisms. Experimental warming inhibited β-glucosidase activity in two soil layers and invertase activity in deep soil, while it stimulated acid phosphatase activity in shallow soil. Both temperature and labile substrates regulate the responses of soil microbial abundances and enzyme activities to warming and affect the coupling relationships of carbon and nitrogen. This study provides a potential microbial mechanism controlling carbon and nitrogen cycling in peatland under climate warming