Single-Photon Counting Detector Scalability for High Photon Efficiency Optical Communications Links

For high photon-efficiency deep space or low power optical communications links, such as the Orion Artemis-2 Optical Communications System (O2O) project, the received optical signal is attenuated to the extent that single- photon detectors are required. For direct-detection receivers operating at 1.55 m wavelength, single-photon detectors including Geiger-mode InGaAs avalanche photon diodes (APDs), and in particular superconducting nanowire single-photon detectors (SNSPDs) offer the highest sensitivity and fastest detection speeds. However, these photon detectors exhibit a recovery time between registered input pulses, effectively reducing the detection efficiency over the recovery interval, resulting in missed photon detections, reduced count rate, and ultimately limiting the achievable data rate. A method to overcome this limitation is to divide the received optical signal into multiple detectors in parallel. Here we analyze this approach for a receiver designed to receive a high photon efficiency serially concatenated pulse position modulation (SCPPM) input waveform. From measured count rate and efficiency data using commercial SNSPDs, we apply a model from which we determine the effective detection efficiency, or blocking loss, for different input signal rates. We analyze the scalability of adding detectors in parallel for different modulation orders and background levels to achieve desired data rates. Finally we show tradeoffs between the number of detectors and the required received optical power, useful for real link design considerations

Cordial Dislike: Reinventing the Celestial Ladies of \u3ci\u3ePearl\u3c/i\u3e and \u3ci\u3ePurgatorio\u3c/i\u3e in Tolkien\u27s Galadriel

Considers the Celestial Lady characters from Pearl and Purgatorio as influences on Tolkien’s Galadriel, in character, appearance, situation, and allegorical significance

Instructional Communication in Secondary Education

Though several early instructional communication studies (e.g., McCroskey & Richmond, 1983) focused on a wide range of participants across what Fredriech and Nussbaum (2005) call the “developmental continuum,”(p. 580) the vast majority of work has centered on the college classroom. Thus, little is known about how instruction occurs in primary and secondary education contexts. Therefore, instructional communication scholars should examine the instructional communication issues faced by primary and secondary school instructors. The purpose of the proposed study was to provide a research agenda for instructional communication scholars regarding communication in the secondary (K-12) educational context. This research was an exploratory study regarding teachers’ communicative strengths and weaknesses. The assessment was guided by the following research questions: As an instructor what do you feel like your communicative strengths are? As an instructor what do you feel like your communicative weaknesses are? The study was conducted through the use of open-ended surveys where secondary teachers were contacted via network sampling of the researchers. Every response was voluntary, and no risks were involved in this research.The data was analyzed through a constant comparative thematic analysis (Braun & Clarke, 2006) guided by grounded theory (Glaser & Strauss, 1967). This approach allowed meaning to emerge from participant responses, rather than subjecting them to pre-existing frameworks. Themes were identified through logical consistency (McCracken, 1988), repetition of phrases, recurrence of meaning, and forcefulness (Owen, 1984). At the 2019 conference, the results of this study were presented, as well as a research agenda to guide future work by instructional communication scholars interested in exploring the processes of teaching and learning at the secondary level

Reflecting on Reflexivity in Realist Evaluation: A Call to Action

Realist evaluation is increasingly utilised across disciplines due to the value of identifying which mechanisms may explain how, and why, particular outcomes are generated in specific contexts. In theory, realist evaluation provides a tangible way to analyse the inherent complexity in many pressing societal challenges. Realist evaluation encourages a mixed methods approach and choosing a suite of methods that are most relevant within a specific project. Yet, navigating a plurality of methods with abstract philosophical concepts brings operational challenges such that, further methodological guidance is needed. Research processes can be opaque and although the relativist epistemology in realist evaluation is acknowledged, the role of the researcher within the research is often unclear. Reflexivity broadly concerns the overt practice to consider how subjective perspective is intertwined in knowledge production. Reflexivity has been a peripheral consideration in realist evaluation to date and this paper outlines what reflexivity entails, how it enhances integrity to realist principles, and practical ways to exercise it. Through a realist lens the evaluation process is itself subject to the impact of mechanisms and reflexivity provides the apparatus to guard against tunnel vision, undertake robust theory generation and adjudication and increase one’s awareness of the influence of personal and organisational entities on research processes and outputs. We conclude with a call to action to the realist community to mobilise reflexivity in a consistent and explicit manner

Nothing Left to Give: Responding to Secondhand Trauma in K-12 Educators

Sarah Downey ’24Major: Spanish/Secondary EducationFaculty Mentor: Dr. Comfort Ateh, Secondary Education In-service K-12 educators working in urban schools experience higher rates of secondhand trauma that result in teacher burnout and turnover. Existent literature is replete with the prevalence of Adverse Childhood Experiences and traumatic events in student populations, physiological and educational effects of trauma, and trauma-informed practices in schools. Nevertheless, teachers lack adequate training and resources to engage in trauma-informed teaching. It is critical for teacher preparation programs to engage teacher candidates in acquiring foundational knowledge and skills to be competent in trauma-informed teaching practices. In this poster presentation, I share the rationale for a trauma-informed teacher education program

Oil Dispersant Effectiveness

This research was supported by the Undergraduate Research Opportunities Program (UROP). I would like to acknowledge Alon McCormick and David Riehm for their guidance and the University of Minnesota for their financial support.Downey, Sarah. (2014). Oil Dispersant Effectiveness. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/163137

Losing Parasocial Friendships over Celebrity Politics: A Cognitive Discrepancies Approach

The present study examines 4 cognitive discrepancy management strategies that media users can use in response to a celebrity making a political statement that runs contrary to their beliefs. The experiment (N = 382) replicates the results using 3 celebrities and 2 attitude object contexts. Exposure to a celebrity making political statements that the media user disagrees with resulted in weaker parasocial relationships with the celebrity and attribution of lesser importance to that issue. Viewers who particularly liked the celebrity prior to the study were more likely to decouple the actor from their line of work to continue enjoying the actor’s media content despite their political disagreement. These findings illuminate the potential consequences of celebrity politics for both the media figures’ stardom and the citizens’ political participation. (PsycInfo Database Record (c) 2022 APA, all rights reserved) Impact Statement Entertainment celebrities often voice their stance on various social issues. The study examines the consequences of this practice, showing that although entertainers can leverage their celebrity status to attenuate public opinion, it might come at the cost of their popularity. These findings can inform efforts to maximize the impact of political advocacy, enhance celebrity management practices, and promote political participation

Sigmoid perforation caused by an ingested chicken bone presenting as right iliac fossa pain mimicking appendicitis: a case report

<p>Abstract</p> <p>Introduction</p> <p>Gastrointestinal perforation due to a foreign body is not unknown. The foreign body often mimics another cause of acute abdomen and requires emergency surgical intervention. The majority of patients do not recall ingesting the foreign body. Perforations have been reported to occur in a pathologically abnormal colon.</p> <p>Case presentation</p> <p>We report an interesting case of a 47-year-old Caucasian man who had a perforation of the sigmoid colon caused by an ingested chicken bone mimicking acute appendicitis. Our patient presented with right iliac fossa pain and local tenderness. When a laparotomy was performed, a chicken bone was found protruding through the sigmoid colon, which was found to lie in the right iliac fossa, thus mimicking acute appendicitis. Our case is different from previously reported cases in that perforation occurred in a non-pathological colon.</p> <p>Conclusion</p> <p>Our case emphasises the fact that the operating surgeon has to be aware of various differential diagnostic possibilities which mimic acute appendicitis. This has implications on the training of junior surgeons who are often involved in performing these procedures, and may do so out of hours. Care needs to be taken while obtaining consent for the necessary operation.</p

Calcifediol-loaded liposomes for local treatment of pulmonary bacterial infections.

The influence of vitamin D3 and its metabolites calcifediol (25(OH)D) and calcitriol on immune regulation and inflammation is well described, and raises the question of potential benefit against bacterial infections. In the current study, 25(OH)D was encapsulated in liposomes to enable aerosolisation, and tested for the ability to prevent pulmonary infection by Pseudomonas aeruginosa. Prepared 25(OH)D-loaded liposomes were nanosized and monodisperse, with a negative surface charge and a 25(OH)D entrapment efficiency of approximately 23%. Jet nebulisation of liposomes was seen to yield an aerosol suitable for tracheo-bronchial deposition. Interestingly, 25(OH)D in either liposomes or ethanolic solution had no effect on the release of the proinflammatory cytokine KC from Pseudomonas-infected murine epithelial cells (LA-4); treatment of infected, human bronchial 16-HBE cells with 25(OH)D liposomes however resulted in a significant reduction in bacterial survival. Together with the importance of selecting an application-appropriate in vitro model, the current study illustrates the feasibility and practicality of employing liposomes as a means to achieve 25(OH)D lung deposition. 25(OH)D-loaded liposomes further demonstrated promising effects regarding prevention of Pseudomonas infection in human bronchial epithelial cells