Resonant dipolar collisions of ultracold molecules induced by microwave dressing

We demonstrate microwave dressing on ultracold, fermionic ${}^{23}$Na${}^{40}$K ground-state molecules and observe resonant dipolar collisions with cross sections exceeding three times the $s$-wave unitarity limit. The origin of these collisions is the resonant alignment of the approaching molecules' dipoles along the intermolecular axis, which leads to strong attraction. We explain our observations with a conceptually simple two-state picture based on the Condon approximation. Furthermore, we perform coupled-channels calculations that agree well with the experimentally observed collision rates. While collisions are observed here as laser-induced loss, microwave dressing on chemically stable molecules trapped in box potentials may enable the creation of strongly interacting dipolar gases of molecules.Comment: 6 pages, 4 figure

Atoms and Molecules Immersed in a Bose-Einstein Condensate

In this thesis work, I demonstrate the creation of dipolar ²³Na⁴⁰K molecules in their absolute ground state directly from Bose polarons, which are dressed fermionic ⁴⁰K impurities immersed in a ²³Na Bose-Einstein condensate. In contrast to Feshbach molecules, Bose polarons at negative scattering length are long-lived in the presence of the BEC. We demonstrate direct photoassociation from Bose polarons to electron- ically excited molecular states, dark resonance spectroscopy of the absolute ground state molecular state, and finally stimulated rapid adiabatic passage (STIRAP) of Bose polarons into the molecular ground state, all in the presence of the Na BEC. This leads to a dense molecular gas at temperatures on the order of 70 nK immersed inside a / subscript = 0.1 BEC.Ph.D

A Mixed-Methods Approach to Exploring Engagement in MoodTech: An Online CBT Intervention for Older Adults with Depression

Thesis (Master's)--University of Washington, 2018In recent years, online cognitive behavioral therapy (CBT) interventions have played an increasing role in treating late-life depression. Previous studies have reported that online CBT interventions can be effective in treating depression and promoting behavioral changes among older participants. However, inadequate engagement could potentially weaken their effectiveness, and the motivations and barriers to participation among older participants in these interventions are less well known. This study aimed to obtain deeper understandings of older participants’ engagement patterns and subjective experiences of MoodTech, an online CBT intervention tailored for older adults with depression. I employed three different methods to analyze diverse forms of data produced during the intervention. There were three aims. First, I characterized the engagement of participants through visual analysis of log data. I visualized the frequencies of their online activities and skills practices, then identified patterns in each measure of engagement. A meta-pattern graph was created to facilitate identification of groups of individuals who shared similar patterns across engagement measures. Second, I conducted a network analysis of the participants who had access to the peer interaction features and compared engagement behaviors in three kinds of peer interaction networks (comments, likes and nudges). Third, I performed a qualitative analysis of the textual data, including messages, posts, comments and thought records of the participants. Using a qualitative analytic method based on Grounded Theory, I examined the application of CBT and how participants responded to CBT and engaged with the intervention. I also explored potential explanations for the observed behaviors in individual and network engagement patterns. With regard to the results, for the first aim, I observed great diversity, but also similarities, in patterns of engagement among participants. For the second aim, I found that the networks of nudges were less dense than the comments and likes networks and there were fewer people involved, which may show that older people attached importance to the actual contents of interactions. Last, I found evidence from the qualitative analysis that many participants learned CBT strategies and practiced them to understand why they were having sustained feelings of depression and low productivity. Some even successfully broke harmful cognitive or behavioral patterns. But other older adults encountered obstacles due to shortcomings in the website design or were reluctant to practice the CBT strategies because of previous unsuccessful experiences with CBT. Overall, engagement behaviors of older adults in online CBT interventions are hard to predict, but can potentially be influenced by technology use habits, contents of social interactions, and previous psychotherapy experiences. Future intervention design may take these findings into consideration and adjust lesson contents for different subgroups of participants, as well as improve the usability of the intervention to meet the needs of older adults. The methodology of this study also shows that combining multiple methods is feasible and provides a richer characterization of engagement from different perspectives

A Study on the Relationship between RPE and sEMG in Dynamic Contraction Based on the GPR Method

The rating of perceived exertion (RPE) and surface electromyography (sEMG) describe exercise intensity subjectively and objectively, while there has been a lack of research on the relationship between them during dynamic contractions to predict exercise intensity, comprehensively. The purpose of this study was to establish a model of the relationship between sEMG and RPE during dynamic exercises. Therefore, 20 healthy male subjects were organized to perform an incremental load test on a cycle ergometer, and the subjects’ RPEs (Borg Scale 6–20) were collected every minute. Additionally, the sEMGs of the subjects’ eight lower limb muscles were collected. The sEMG features based on time domain, frequency domain and time–frequency domain methods were extracted, and the relationship model was established using Gaussian process regression (GPR). The results show that the sEMG and RPE of the selected lower limb muscles are significantly correlated (p < 0.05) but that they have different monotonic correlation degrees. The model that was established with all three domain features displayed optimal performance and when the RPE was 13, the prediction error was the smallest. The study is significant for lower limb muscle training strategy and quantification of training intensity from both subjective and objective aspects, and lays a foundation for sEMG further applications in rehabilitation medicine and sports training

A Study on the Relationship between RPE and sEMG in Dynamic Contraction Based on the GPR Method

The rating of perceived exertion (RPE) and surface electromyography (sEMG) describe exercise intensity subjectively and objectively, while there has been a lack of research on the relationship between them during dynamic contractions to predict exercise intensity, comprehensively. The purpose of this study was to establish a model of the relationship between sEMG and RPE during dynamic exercises. Therefore, 20 healthy male subjects were organized to perform an incremental load test on a cycle ergometer, and the subjects’ RPEs (Borg Scale 6–20) were collected every minute. Additionally, the sEMGs of the subjects’ eight lower limb muscles were collected. The sEMG features based on time domain, frequency domain and time–frequency domain methods were extracted, and the relationship model was established using Gaussian process regression (GPR). The results show that the sEMG and RPE of the selected lower limb muscles are significantly correlated (p < 0.05) but that they have different monotonic correlation degrees. The model that was established with all three domain features displayed optimal performance and when the RPE was 13, the prediction error was the smallest. The study is significant for lower limb muscle training strategy and quantification of training intensity from both subjective and objective aspects, and lays a foundation for sEMG further applications in rehabilitation medicine and sports training

Risk Factors Affecting Muscle Mass Decline in Maintenance Hemodialysis Patients

Objective. There is a high prevalence of sarcopenia in maintenance hemodialysis (MHD) patients, which is known to be associated with increased mortality. This study is aimed at analyzing the risk factors affecting muscle mass decline in MHD patients. Methods. This retrospective study included MHD patients who underwent two body composition assessments in October 2013 and November 2017. Depending on whether there was muscle loss or not, the patients were divided into a normal muscle mass (NMM) group and a muscle mass decline (MMD) group. According to the muscle mass decline rate, patients in the MMD group were further classified into a low-rate group and a high-rate group. Biochemical variables, serum vitamin concentrations, anthropometric data, SGA, muscle mass, handgrip, and daily steps were assessed. Risk factors for muscle mass decline were screened by multivariate logistic analysis and linear regression analysis. Results. Of the 72 MHD patients included in this study, 33 were male and 39 were female with a mean age of 56.80±10.86 years and a mean dialysis duration of 7.50±5.20 years. Age (P=.014) and serum 25(OH)D (P=.040) were found to be associated with a higher risk of muscle mass decline after adjusting for gender, dialysis vintage, albumin, and hs-CRP (P=.040). Further analysis found that dialysis vintage (β=0.285, P=.030), 25(OH)D (β=−0.351, P=.007), and log NT-proBNP (β=0.312, P=.020) were risk factors associated with the muscle mass decline rate in MHD patients. Conclusion. Age and serum 25(OH)D were associated with a higher risk of muscle mass decline, while 25(OH)D, dialysis vintage, and NT-proBNP were associated with the muscle mass decline rate in MHD patients

Deterministic bulk-boundary correspondences for skin and edge modes in a general two-band non-Hermitian system

In isolated Hermitian systems, the bulk-boundary correspondence is generally thought of as a compelling principle guiding the occurrence of robust edge states through the topological invariants of the bulk. However, in open non-Hermitian systems that support non-Hermitian skin effects, the universality of the bulk-boundary correspondence has so far remained disputable in spite of being subjected to intensive studies. Here we provide analytical and numerical evidence of bulk-boundary correspondences for both skin and edge modes in 1D two-band non-Hermitian systems within the framework of a prototypical non-Hermitian Su-Schrieffer-Heeger model. Two different topological winding numbers, one on a Brillouin zone and the other on a generalized Brillouin zone, are defined to fully characterize the topological phases of matter and to understand such deterministic correspondences. In addition to the exact solutions for bulk states, we also obtain explicit solution forms for edge modes along with analytical conditions for their existence and localization, all exhibiting remarkable agreement with numerical results. Our results solve the elusive non-Hermitian topology and may facilitate experimental investigations of bulk-boundary correspondence in a wide range of non-Hermitian systems

Experiences and Challenges of Emerging Online Health Services Combating COVID-19 in China: Retrospective, Cross-Sectional Study of Internet Hospitals

BackgroundInternet-based online virtual health services were originally an important way for the Chinese government to resolve unmet medical service needs due to inadequate medical institutions. Its initial development was not well received. Then, the unexpected COVID-19 pandemic produced a tremendous demand for telehealth in a short time, which stimulated the explosive development of internet hospitals. The Second Affiliated Hospital of Zhejiang University (SAHZU) has taken a leading role in the construction of internet hospitals in China. The pandemic triggered the hospital to develop unique research on health service capacity under strict quarantine policies and to predict long-term trends. ObjectiveThis study aims to provide policy enlightenment for the construction of internet-based health services to better fight against COVID-19 and to elucidate future directions through an in-depth analysis of 2 years of online health service data gleaned from SAHZU’s experiences and lessons learned. MethodsWe collected data from SAHZU Internet Hospital from November 1, 2019, to September 16, 2021. Data from over 900,000 users were analyzed with respect to demographic characteristics, demands placed on departments by user needs, new registrations, and consultation behaviors. Interrupted time series (ITS) analysis was adopted to evaluate the impact of this momentous emergency event and its long-term trends. With theme analysis and a defined 2D model, 3 investigations were conducted synchronously to determine users’ authentic demands on online hospitals. ResultsThe general profile of internet hospital users is young or middle-aged women who live in Zhejiang and surrounding provinces. The ITS model indicated that, after the intervention (the strict quarantine policies) was implemented during the outbreak, the number of internet hospital users significantly increased (β_2=105.736, P<.001). Further, long-term waves of COVID-19 led to an increasing number of users following the outbreak (β_3=0.167, P<.001). In theme analysis, we summarized 8 major demands by users of the SAHZU internet hospital during the national shutdown period and afterwards. Online consultations and information services were persistent and universal demands, followed by concerns about medical safety and quality, time, and cost. Users’ medical behavior patterns changed from onsite to online as internet hospital demands increased. ConclusionsThe pandemic has spawned the explosive growth of telehealth; as a public tertiary internet hospital, the SAHZU internet hospital is partially and irreversibly integrated into the traditional medical system. As we shared the practical examples of 1 public internet hospital in China, we put forward suggestions about the future direction of telehealth. Vital experience in the construction of internet hospitals was provided in the normalization of COVID-19 prevention and control, which can be demonstrated as a model of internet hospital management practice for other medical institutions