Test and evaluate passive orbital disconnect struts (PODS 3)

The objectives of the Passive Orbital Disconnect Struts (PODS) test are to evaluate modal resonance of the PODS-III supports to obtain engineering data required for use of PODS-III on flight systems; determine possible performance improvements in large LO2/LH2 space applications. (1) Modal Vibration Tests. A modal resonance survey is performed on a set of six PODS-III struts assembled in a dewar simulator. The survey conditions simulate both launch and orbital loadings of the struts. The orbital load range spans a full to an empty tank. The frequencies surveyed cover the range consistent with Shuttle qualification requirements and the principal resonant modes of the strut system. (2) Benefit study. The benefit of using PODS-III supports on OTV and Space Station LO sub 2 and LH sub 2 reference tanks was compared to nondisconnect supports. Four LO sub 2 and LH sub 2 tanks were studied under various conditions: (1) holding the launch resonance at 35 Hz and varying the orbit resonance; (2) analyzing both full and emtpy tanks at launch; (3) varying orbit boundary temperaure; (4) varying the number of struts; (5) varying orbit times; and (6) using or not using vapor cooling

KRb Feshbach Resonances: Modeling the interatomic potential

We have observed 28 heteronuclear Feshbach resonances in 10 spin combinations of the hyperfine ground states of a 40K 87Rb mixture. The measurements were performed by observing the loss rates from an atomic mixture at magnetic fields between 0 and 700 G. This data was used to significantly refine an interatomic potential derived from molecular spectroscopy, yielding a highly consistent model of the KRb interaction. Thus, the measured resonances can be assigned to the corresponding molecular states. In addition, this potential allows for an accurate calculation of the energy differences between highly excited levels and the rovibrational ground level. This information is of particular relevance for the formation of deeply bound heteronuclear molecules. Finally, the model is used to predict Feshbach resonances in mixtures of 87Rb combined with 39K or 41K.Comment: 4 pages, 3 figure

Radio frequency association of heteronuclear Feshbach molecules

We present a detailed analysis of the production efficiency of weakly bound heteronuclear KRb-Feshbach molecules using radio frequency association in a harmonic trap. The efficiency was measured in a wide range of temperatures, binding energies and radio frequencies. A comprehensive analytical model is presented, explaining the observed asymmetric spectra and achieving good quantitative agreement with the measured production rates. This model provides a deep understanding of the molecule association process and paves the way for future experiments which rely on Feshbach molecules e.g. for the production of deeply bound molecules.Comment: 5 pages, 4 figure

Parametric amplification of vacuum fluctuations in a spinor condensate

Parametric amplification of vacuum fluctuations is crucial in modern quantum optics, enabling the creation of squeezing and entanglement. We demonstrate the parametric amplification of vacuum fluctuations for matter waves using a spinor F=2 Rb-87 condensate. Interatomic interactions lead to correlated pair creation in the m_F= +/- 1 states from an initial unstable m_F=0 condensate, which acts as a vacuum for m_F unequal 0. Although this pair creation from a pure m_F=0 condensate is ideally triggered by vacuum fluctuations, unavoidable spurious initial m_F= +/- 1 atoms induce a classical seed which may become the dominant triggering mechanism. We show that pair creation is insensitive to a classical seed for sufficiently large magnetic fields, demonstrating the dominant role of vacuum fluctuations. The presented system thus provides a direct path towards the generation of non-classical states of matter on the basis of spinor condensates.Comment: 5 pages, 4 figure

Platforms and the pandemic: A case study of fashion rental platforms during COVID-19

From Airbnb to Uber, the sharing or platform economy has reshaped many aspects of our economy and society. In recent years, fashion rental platforms have gained in popularity, fuelling the introduction of the platform economy in fashion. When the COVID-19 pandemic hit, the impact on fashion rental platforms was abrupt, with demand disappearing seemingly overnight as events were cancelled and many people began working from home. Drawing on a case study of fashion rental platforms, we explore the immediate consequences of the pandemic on this segment of the platform economy, examining both the challenges these platforms face in the short term and the strategies platforms have adopted to try and weather the storm. We highlight how the impact of the COVID-19 pandemic on fashion rental platforms thus far intersects with issues pertaining to value creation, precarious work, gender, and sustainable consumption. In doing so, we reflect on how fashion rental platforms inform understanding of the platform economy more broadly and conclude by suggesting themes for future research

My Wardrobe in the Cloud: An International Comparison of Fashion Rental

In response to the 2008 global financial crisis, a range of disruptive business model innovations emerged. The fashion industry saw the introduction of fashion rental platforms, aimed at appealing to price-conscious consumers still hungry for the latest styles. While these new business models filled a gap in the market and saw, in some cases, profit in the millions, the phenomenon remained rather niche. The recent pandemic, alongside other isomorphic pressures, have put further constraints on these fashion rental businesses and their entrepreneurs, leaving them struggling in the current economic climate. This chapter explores the entrepreneurial motivations behind rental platforms, the different platform models in operation, and the challenges these businesses face in the 21st century, including increased technological developments, environmental sustainability, and external pressures, such as the most recent pandemic, which saw economies shutting down. Empirically, the authors draw upon a novel dataset comprising six international case studies

Multi-resonant spinor dynamics in a Bose-Einstein condensate

We analyze the spinor dynamics of a Rb-87 F=2 condensate initially prepared in the m_F=0 Zeeman sublevel. We show that this dynamics, characterized by the creation of correlated atomic pairs in m_F=+/-1, presents an intriguing multi-resonant magnetic field dependence induced by the trap inhomogeneity. This dependence is directly linked to the most unstable Bogoliubov spin excitations of the initial m_F = 0 condensate, showing that, in general, even a qualitative understanding of the pair creation efficiency in a spinor condensate requires a careful consideration of the confinement.Comment: 5 pages, 4 figure

Investigating Relationships Among Self-Efficacy, Mood, and Anxiety Using Digital Technologies: Randomized Controlled Trial.

BACKGROUND Digital tools assessing momentary parameters and offering interventions in people's daily lives play an increasingly important role in mental health research and treatment. Ecological momentary assessment (EMA) makes it possible to assess transient mental health states and their parameters. Ecological momentary interventions (EMIs) offer mental health interventions that fit well into individuals' daily lives and routines. Self-efficacy is a transdiagnostic construct that is commonly associated with positive mental health outcomes. OBJECTIVE The aim of our study assessing mood, specific self-efficacy, and other parameters using EMA was 2-fold. First, we wanted to determine the effects of daily assessed moods and dissatisfaction with social contacts as well as the effects of baseline variables, such as depression, on specific self-efficacy in the training group (TG). Second, we aimed to explore which variables influenced both groups' positive and negative moods during the 7-day study period. METHODS In this randomized controlled trial, we applied digital self-efficacy training (EMI) to 93 university students with elevated self-reported stress levels and daily collected different parameters, such as mood, dissatisfaction with social contacts, and specific self-efficacy, using EMA. Participants were randomized to either the TG, where they completed the self-efficacy training combined with EMA, or the control group, where they completed EMA only. RESULTS In total, 93 university students participated in the trial. Positive momentary mood was associated with higher specific self-efficacy in the evening of the same day (b=0.15, SE 0.05, P=.005). Higher self-efficacy at baseline was associated with reduced negative mood during study participation (b=-0.61, SE 0.30, P=.04), while we could not determine an effect on positive mood. Baseline depression severity was significantly associated with lower specific self-efficacy over the week of the training (b=-0.92, SE 0.35, P=.004). Associations between higher baseline anxiety with higher mean negative mood (state anxiety: b=0.78, SE 0.38, P=.04; trait anxiety: b=0.73, SE 0.33, P=.03) and lower mean positive mood (b=-0.64, SE 0.28, P=.02) during study participation were found. Emotional flexibility was significantly enhanced in the TG. Additionally, dissatisfaction with social contacts was associated with both a decreased positive mood (b=-0.56, SE 0.15, P<.001) and an increased negative mood (b=0.45, SE 0.12, P<.001). CONCLUSIONS This study showed several significant associations between mood and self-efficacy as well as those between mood and anxiety in students with elevated stress levels, for example, suggesting that improving mood in people with low mood could enhance the effects of digital self-efficacy training. In addition, engaging in 1-week self-efficacy training was associated with increased emotional flexibility. Future work is needed to replicate and investigate the training's effects in other groups and settings. TRIAL REGISTRATION ClinicalTrials.gov NCT05617248; https://clinicaltrials.gov/study/NCT05617248

Investigating Relationships Among Self-Efficacy, Mood, and Anxiety Using Digital Technologies: Randomized Controlled Trial

Background Digital tools assessing momentary parameters and offering interventions in people’s daily lives play an increasingly important role in mental health research and treatment. Ecological momentary assessment (EMA) makes it possible to assess transient mental health states and their parameters. Ecological momentary interventions (EMIs) offer mental health interventions that fit well into individuals’ daily lives and routines. Self-efficacy is a transdiagnostic construct that is commonly associated with positive mental health outcomes. Objective The aim of our study assessing mood, specific self-efficacy, and other parameters using EMA was 2-fold. First, we wanted to determine the effects of daily assessed moods and dissatisfaction with social contacts as well as the effects of baseline variables, such as depression, on specific self-efficacy in the training group (TG). Second, we aimed to explore which variables influenced both groups’ positive and negative moods during the 7-day study period. Methods In this randomized controlled trial, we applied digital self-efficacy training (EMI) to 93 university students with elevated self-reported stress levels and daily collected different parameters, such as mood, dissatisfaction with social contacts, and specific self-efficacy, using EMA. Participants were randomized to either the TG, where they completed the self-efficacy training combined with EMA, or the control group, where they completed EMA only. Results In total, 93 university students participated in the trial. Positive momentary mood was associated with higher specific self-efficacy in the evening of the same day (b=0.15, SE 0.05, P=.005). Higher self-efficacy at baseline was associated with reduced negative mood during study participation (b=–0.61, SE 0.30, P=.04), while we could not determine an effect on positive mood. Baseline depression severity was significantly associated with lower specific self-efficacy over the week of the training (b=–0.92, SE 0.35, P=.004). Associations between higher baseline anxiety with higher mean negative mood (state anxiety: b=0.78, SE 0.38, P=.04; trait anxiety: b=0.73, SE 0.33, P=.03) and lower mean positive mood (b=–0.64, SE 0.28, P=.02) during study participation were found. Emotional flexibility was significantly enhanced in the TG. Additionally, dissatisfaction with social contacts was associated with both a decreased positive mood (b=–0.56, SE 0.15, P<.001) and an increased negative mood (b=0.45, SE 0.12, P<.001). Conclusions This study showed several significant associations between mood and self-efficacy as well as those between mood and anxiety in students with elevated stress levels, for example, suggesting that improving mood in people with low mood could enhance the effects of digital self-efficacy training. In addition, engaging in 1-week self-efficacy training was associated with increased emotional flexibility. Future work is needed to replicate and investigate the training’s effects in other groups and settings. Trial Registration ClinicalTrials.gov NCT05617248; https://clinicaltrials.gov/study/NCT0561724