Fermi edge singularity and finite frequency spectral features in a semi-infinite 1D wire

We theoretically study a charge qubit interacting with electrons in a semi-infinite 1D wire. The system displays the physics of the Fermi edge singularity. Our results generalize known results for the Fermi-edge system to the regime where excitations induced by the qubit can resolve the spatial structure of the scattering region. We find resonant features in the qubit tunneling rate as a function of the qubit level splitting. They occur at integer multiples of h times v_F/l. Here v_F is the Fermi velocity of the electrons in the wire, and l is the distance from the tip of the wire to the point where it interacts with the qubit. These features are due to a single coherent charge fluctuation in the electron gas, with a half-wavelength that fits into l an integer number of times. As the coupling between the qubit and the wire is increased, the resonances are washed out. This is a clear signature of the increasingly violent Fermi-sea shake-up that accompanies strong coupling.Comment: 11 page

Evaluation of turn-off dV/dt controllability and switching characteristics of 1.2 kV GaN polarisation superjunction heterostructure field-effect transistors

Japanese Journal of Applied Physics The Japan Society of Applied Physics, find out more REGULAR PAPER • THE FOLLOWING ARTICLE ISOPEN ACCESS Evaluation of turn-off dV/dt controllability and switching characteristics of 1.2 kV GaN polarisation superjunction heterostructure field-effect transistors Alireza Sheikhan1, Sankara Narayanan Ekkanath Madathil1, Hiroji Kawai2, Shuichi Yagi2 and Hironobu Narui2 Published 5 July 2023 • © 2023 The Author(s). Published on behalf of The Japan Society of Applied Physics by IOP Publishing Ltd Japanese Journal of Applied Physics, Volume 62, Number 6 Citation Alireza Sheikhan et al 2023 Jpn. J. Appl. Phys. 62 064502 DOI 10.35848/1347-4065/acd975 DownloadArticle PDF Figures References Download PDF 290 Total downloads Turn on MathJax Share this article Share this content via email Share on Facebook (opens new window) Share on Twitter (opens new window) Share on Mendeley (opens new window) Hide article and author information Author e-mails [email protected] Author affiliations 1 Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, United Kingdom 2 Powdec K.K. Oyama, Tochigi, Japan ORCID iDs Alireza Sheikhan https://orcid.org/0000-0002-2207-1593 Dates Received 16 April 2023 Revised 18 May 2023 Accepted 26 May 2023 Published 5 July 2023 Check for updates using Crossmark Buy this article in print Journal RSS Sign up for new issue notifications Create citation alert Abstract Gallium nitride (GaN) devices inherently offer many advantages over silicon power devices, including a higher operating frequency, lower on-state resistance and higher operating temperature capabilities, which can enable higher power density and more efficient power electronics. Turn-off dV/dt controllability plays a key role in determining common-mode voltage in electrical drives and traction inverter applications. The fast-switching edges of GaN can introduce challenges such as electromagnetic interference, premature insulation failure and high overshoot voltages. In this paper, the device working principle, characteristics and dV/dt controllability of 1.2 kV GaN polarisation superjunction (PSJ) heterostructure FETs (HFETs) are presented. The effect of gate driving parameters and load conditions on turn-off dV/dt are investigated. It is shown that in PSJ HFETs the dV/dt can be effectively controlled to as low as 1 kV μs−1 by controlling the gate, with a minimum increase in switching losses. These results are highly encouraging for the application of the devices in motor drives

Analysis of 1.2kV GaN polarisation superjunction diode surge current capability

Surge current capability of power diodes is one of the essential parameters that needs to be considered for high power density operations in power electronic applications. Gallium Nitride (GaN) is emerging as the next generation of power semiconductor devices due to its superior material characteristics. This work presents the device working principle, characteristics, and the surge capability of 1200V GaN polarisation superjunction (PSJ) hybrid diodes. The experimental results show that the GaN PSJ diode can withstand a surge current of 60A which is around 8 times its rated current and a surge energy of 5.4J. Additionally, despite having a merged PiN and Schottky structure, no bipolar current flow due to the activation of p-doped GaN can be observed until breakdown. This can also be confirmed through the device forward characteristic which shows a unique saturation behaviour at about 76A without any bipolar region

Measuring Sexual Performance: Development and Psychometric Properties of the Sexual Performance Questionnaire in Iranian People with Spinal Cord Injury

Sexual performance refers to activities served by sexual capacity and motivation. As a culturally sensitive issue, to date the scalar invariance of sexual performance has not been examined for Iranians with spinal cord injuries (SCIs). Aim: To develop and assess properties of an instrument evaluating sexual performance of an Iranian population with SCIs., in Brain and Spinal Cord Injury Research Center (BASIR), Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran. Using multi-modal methods, we developed and assessed the Sexual Performance Questionnaire (SPQ). This included collecting expert opinions; engaging with patients with SCI referred to BASIR; pilot testing to assess the scale; and a formal investigation. Participants (men = 156, women = 58) completed the SPQ. Internal consistency and reliability were measured using Cronbach’s α coefficient. Content and face validity were examined by academic experts. Construct validity was assessed by examining convergent and discriminant validity. Finally, exploratory factor analysis was used to extract the factor structure of the questionnaire. The Cronbach’s α coefficient was 0.77. There was a significant (p = 0.04) correlation (r = − 0.23) between the SPQ score and age. Those with a partner scored higher (p = 0.001). We found three components: Spouse as initiator, self-initiation, and genital-oriented sex which accounted for 59 of the observed variance. The face and content validity was approved by an expert committee. The development and application of the 13-item SPQ provides a thorough understanding of sexual performance amongst persons with SCI. It facilitates the development of efficient sexual rehabilitation interventions and SCI-specific sexuality education programs. © 2020, Springer Science+Business Media, LLC, part of Springer Nature

Pragmatic functions of ‘sort of’ in Persian

It goes without saying that as a pragmatic phenomenon, vagueness has over the past few years been a topic of extensive research. However, a huge gap still exists when it comes to the investigation of how vagueness is expressed across different languages and cultures. In the present study, we have put under scrutiny the pragmatic functions of ‘sort of’, a vague expression, in Persian conversation with a view to making cross-linguistic comparisons between different languages possible. Besides confirming the fact that the vague item ‘sort of’ enables interactants to fulfil a wide variety of functions in interactional settings, particularly in face-to-face interactions, the current study reveals that the expression in question can also serve to signal ‘a moment of awkwardness’ as well as the presence of ‘inferable information’. With the former function, ‘sort of’ signals that the speaker is experiencing a feeling of inconvenience and embarrassment. When used as an inferable information signal, however, ‘sort of’ indicates that the utterance has been inferred from the previous or current exchange

Unsubstantiated health claims for COVID-19 infections are led by cannabidiol: return of snake oil medicine

Abstract Background The United States Food and Drug Administration (FDA) monitors, inspects, and enforces the promotion of products by companies that claim to mitigate, prevent, treat, diagnose, or cure COVID-19. The introduction of COVID-19-related diagnostics and therapeutics during the pandemic has highlighted the significance of rigorous clinical trials to ensure safety and efficacy of such interventions. The objective of this report is to provide a descriptive review of promotional violations of health products for COVID-19 infection. Methods Warning letters issued by the FDA’s Center for Drug Evaluation and Research were retrieved over an 18 month period (March 6, 2020, to August 30, 2021) to identify promotional violations. FDA violation letters categorized as “Unapproved and Misbranded Products Related to Coronavirus Disease 2019 (COVID-19)” were reviewed. A content analysis was performed for each letter to identify categories for product type, promotional venue, violation type, and country of origin. For cannabidiol-related violations, a content analysis was repeated within its own product category. Results A total of 130 letters were reported. Across all letters, cannabidiol products were the most frequent subject of violation (15/130; 11.5%). Of the cannabidiol letters, all reported the promotion of unapproved products (15/15; 100%), misbranding (15/15; 100%), and/or had claims that lacked scientific substantiation (14/15; 93.3%). All promotional violations were linked to websites (15/15; 100%), along with other mainstream venues: Facebook, Instagram, YouTube, Twitter, LinkedIn, and email. Lastly, the cannabidiol products were described to provide therapeutic benefit to COVID-19, by acting as an anti-viral (5; 33.3%), pro-inflammatory (1; 6.7%), anti-inflammatory (7; 46.7%), immune-booster (5; 40%), immune-suppressor (2; 13.3%), and/or other (2; 13.3%). Conclusion Despite the urgent need for COVID-19 treatments, promotional material by companies must comply with standard regulatory requirements, namely substantiation of claims. As the pandemic persists, the FDA must continue their efforts to monitor, inspect, and enforce violative companies. Cannabidiol-related substances led the spectrum of products with unsubstantiated claims to treat COVID-19 infection. Improving awareness among the public, healthcare providers, and stakeholders highlights the value of drug approval process, while protecting public safety

Coherent backscattering of electromagnetic waves in random media

NatuurwetenskappeInstituut Vir Teoretiese FisikaPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]