108 research outputs found
Investigating the Effects of Robot Engagement Communication on Learning from Demonstration
Robot Learning from Demonstration (RLfD) is a technique for robots to derive
policies from instructors' examples. Although the reciprocal effects of student
engagement on teacher behavior are widely recognized in the educational
community, it is unclear whether the same phenomenon holds true for RLfD. To
fill this gap, we first design three types of robot engagement behavior
(attention, imitation, and a hybrid of the two) based on the learning
literature. We then conduct, in a simulation environment, a within-subject user
study to investigate the impact of different robot engagement cues on humans
compared to a "without-engagement" condition. Results suggest that engagement
communication significantly changes the human's estimation of the robots'
capability and significantly raises their expectation towards the learning
outcomes, even though we do not run actual learning algorithms in the
experiments. Moreover, imitation behavior affects humans more than attention
does in all metrics, while their combination has the most profound influences
on humans. We also find that communicating engagement via imitation or the
combined behavior significantly improve humans' perception towards the quality
of demonstrations, even if all demonstrations are of the same quality.Comment: Under revie
ALens: An Adaptive Domain-Oriented Abstract Writing Training Tool for Novice Researchers
The significance of novice researchers acquiring proficiency in writing
abstracts has been extensively documented in the field of higher education,
where they often encounter challenges in this process. Traditionally, students
have been advised to enroll in writing training courses as a means to develop
their abstract writing skills. Nevertheless, this approach frequently falls
short in providing students with personalized and adaptable feedback on their
abstract writing. To address this gap, we initially conducted a formative study
to ascertain the user requirements for an abstract writing training tool.
Subsequently, we proposed a domain-specific abstract writing training tool
called ALens, which employs rhetorical structure parsing to identify key
concepts, evaluates abstract drafts based on linguistic features, and employs
visualization techniques to analyze the writing patterns of exemplary
abstracts. A comparative user study involving an alternative abstract writing
training tool has been conducted to demonstrate the efficacy of our approach.Comment: Accepted by HHME/CHCI 202
Storyfier: Exploring Vocabulary Learning Support with Text Generation Models
Vocabulary learning support tools have widely exploited existing materials,
e.g., stories or video clips, as contexts to help users memorize each target
word. However, these tools could not provide a coherent context for any target
words of learners' interests, and they seldom help practice word usage. In this
paper, we work with teachers and students to iteratively develop Storyfier,
which leverages text generation models to enable learners to read a generated
story that covers any target words, conduct a story cloze test, and use these
words to write a new story with adaptive AI assistance. Our within-subjects
study (N=28) shows that learners generally favor the generated stories for
connecting target words and writing assistance for easing their learning
workload. However, in the read-cloze-write learning sessions, participants
using Storyfier perform worse in recalling and using target words than learning
with a baseline tool without our AI features. We discuss insights into
supporting learning tasks with generative models.Comment: To appear at the 2023 ACM Symposium on User Interface Software and
Technology (UIST); 16 pages (7 figures, 23 tables
Antiarrhythmic and proarrhythmic effects of subcutaneous nerve stimulation in ambulatory dogs
Background
High output subcutaneous nerve stimulation (ScNS) remodels the stellate ganglia and suppresses cardiac arrhythmia.
Objective
To test the hypothesis that long duration low output ScNS causes cardiac nerve sprouting, increases plasma norepinephrine concentration and the durations of paroxysmal atrial tachycardia (PAT) in ambulatory dogs.
Methods
We prospectively randomized 22 dogs (11 males and 11 females) into 5 different output groups for 2 months of ScNS: 0 mA (sham) (N=6), 0.25 mA (N=4), 1.5 mA (N=4), 2.5 mA (N=4) and 3.5 mA (N=4).
Results
As compared with baseline, the changes of the durations of PAT episodes per 48 hours were significantly different among different groups (sham, -5.0±9.5 s; 0.25 mA 95.5±71.0 s; 1.5 mA, -99.3±39.6 s; 2.5 mA, -155.3±87.8 s and 3.5 mA, -76.3±44.8 s, p<0.001). The 3.5 mA group had greater reduction of sinus heart rate than the sham group (-29.8±15.0 bpm vs -14.5±3.0 bpm, p=0.038). Immunohistochemical studies showed that the 0.25 mA group had a significantly increased while 2.5 mA and 3.5 mA stimulation had a significantly reduced growth-associated protein 43 nerve densities in both atria and ventricles. The plasma Norepinephrine concentrations in 0.25 mA group was 5063.0±4366.0 pg/ml, which was significantly higher than other groups of dogs (739.3±946.3, p=0.009). There were no significant differences in the effects of simulation between males and females.
Conclusions
In ambulatory dogs, low output ScNS causes cardiac nerve sprouting, increases plasma norepinephrine concentration and the duration of PAT episodes while high output ScNS is antiarrhythmic
Inhibition of Small-Conductance, Ca2+-Activated K+ Current by Ondansetron
Background: Small-conductance Ca2+-activated K+ channels (SK channels) have been proposed as antiarrhythmic targets for the treatment of atrial fibrillation. We previously demonstrated that the 5-HT3 receptor antagonist ondansetron inhibits heterologously expressed, human SK2 (hSK2) currents as well as native cardiac SK currents in a physiological extra-/intracellular [K+] gradient at therapeutic (i.e., sub-micromolar) concentrations. A recent study, using symmetrical [K+] conditions, challenged this result. The goal of the present study was to revisit the inhibitory effect of ondansetron on hSK2-mediated currents in symmetrical [K+] conditions. Experimental Approach: The whole-cell patch clamp technique was used to investigate the effects of ondansetron and apamin on hSK2-mediated currents expressed in HEK 293 cells. Currents were measured in symmetrical [K+] conditions in the presence of 100 nM [Ca2+]o. Results: Expression of hSK2 produced inwardly rectifying whole-cell currents in the presence of 400 nM free cytosolic Ca2+. Ondansetron inhibited whole-cell hSK2 currents with IC 50 values of 154 and 113 nM at -80 and 40 mV, respectively. Macroscopic current inhibited by ondansetron and current inhibited by apamin exhibited inwardly rectifying current-voltage relationships with similar reversal potentials (apamin, ∼5 mV and ondansetron, ∼2 mV). Ondansetron (1 μM) in the continuing presence of apamin (100 nM) had no effect on hSK2-mediated whole-cell currents. Wild-type HEK 293 cells did not express ondansetron- or apamin-sensitive currents. Conclusion: Ondansetron in sub-micromolar concentrations inhibits hSK2 currents even under altered ionic conditions
Phospholamban Regulates Nuclear Ca2+ Stores and Inositol 1,4,5-Trisphosphate Mediated Nuclear Ca2+ Cycling in Cardiomyocytes
AIMS:
Phospholamban (PLB) is the key regulator of the cardiac Ca2+ pump (SERCA2a)-mediated sarcoplasmic reticulum Ca2+ stores. We recently reported that PLB is highly concentrated in the nuclear envelope (NE) from where it can modulate perinuclear Ca2+ handling of the cardiomyocytes (CMs). Since inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) mediates nuclear Ca2+ release, we examined whether the nuclear pool of PLB regulates IP3-induced nuclear Ca2+ handling.
METHODS AND RESULTS:
Fluo-4 based confocal Ca2+ imaging was performed to measure Ca2+ dynamics across both nucleus and cytosol in saponin-permeabilized CMs isolated from wild-type (WT) or PLB-knockout (PLB-KO) mice. At diastolic intracellular Ca2+ ([Ca2+]i = 100 nM), the Fab fragment of the monoclonal PLB antibody (anti-PLB Fab) facilitated the formation and increased the length of spontaneous Ca2+ waves (SCWs) originating from the nuclear region in CMs from WT but not from PLB-KO mice. We next examined nuclear Ca2+ activities at basal condition and after sequential addition of IP3, anti-PLB Fab, and the IP3R inhibitor 2-aminoethoxydiphenyl borate (2-APB) at a series of [Ca2+]i. In WT mice, at 10 nM [Ca2+]i where ryanodine receptor (RyR2) based spontaneous Ca2+ sparks rarely occurred, IP3 increased fluorescence amplitude (F/F0) of overall nuclear region to 1.19 ± 0.02. Subsequent addition of anti-PLB Fab significantly decreased F/F0 to 1.09 ± 0.02. At 50 nM [Ca2+]i, anti-PLB Fab not only decreased the overall nuclear F/F0 previously elevated by IP3, but also increased the amplitude and duration of spark-like nuclear Ca2+ release events. These nuclear Ca2+ releases were blocked by 2-APB. At 100 nM [Ca2+]i, IP3 induced short SCWs originating from nucleus. Anti-PLB Fab transformed those short waves into long SCWs with propagation from the nucleus into the cytosol. In contrast, neither nuclear nor cytosolic Ca2+ dynamics was affected by anti-PLB Fab in CMs from PLB-KO mice in all these conditions. Furthermore, in WT CMs pretreated with RyR2 blocker tetracaine, IP3 and anti-PLB Fab still increased the magnitude of nuclear Ca2+ release but failed to regenerate SCWs. Finally, anti-PLB Fab increased low Ca2+ affinity mag-fluo 4 fluorescence intensity in the lumen of NE of nuclei isolated from WT but not in PLB-KO mice.
CONCLUSION:
PLB regulates nuclear Ca2+ handling. By increasing Ca2+ uptake into lumen of the NE and perhaps other perinuclear membranes, the acute reversal of PLB inhibition decreases global Ca2+ concentration at rest in the nucleoplasm, and increases Ca2+ release into the nucleus, through mechanisms involving IP3R and RyR2 in the vicinity
PromotionLens: Inspecting Promotion Strategies of Online E-commerce via Visual Analytics
Promotions are commonly used by e-commerce merchants to boost sales. The
efficacy of different promotion strategies can help sellers adapt their
offering to customer demand in order to survive and thrive. Current approaches
to designing promotion strategies are either based on econometrics, which may
not scale to large amounts of sales data, or are spontaneous and provide little
explanation of sales volume. Moreover, accurately measuring the effects of
promotion designs and making bootstrappable adjustments accordingly remains a
challenge due to the incompleteness and complexity of the information
describing promotion strategies and their market environments. We present
PromotionLens, a visual analytics system for exploring, comparing, and modeling
the impact of various promotion strategies. Our approach combines
representative multivariant time-series forecasting models and well-designed
visualizations to demonstrate and explain the impact of sales and promotional
factors, and to support "what-if" analysis of promotions. Two case studies,
expert feedback, and a qualitative user study demonstrate the efficacy of
PromotionLens.Comment: IEEE Transactions on Visualization and Computer Graphics (Proc. IEEE
VIS 2022
Sex‐specific activation of SK current by isoproterenol facilitates action potential triangulation and arrhythmogenesis in rabbit ventricles
Sex has a large influence on cardiac electrophysiological properties. Whether sex differences exist in apamin‐sensitive small conductance Ca2+‐activated K+ (SK) current (IKAS) remains unknown. We performed optical mapping, transmembrane potential, patch clamp, western blot and immunostaining in 62 normal rabbit ventricles, including 32 females and 30 males. IKAS blockade by apamin only minimally prolonged action potential (AP) duration (APD) in the basal condition for both sexes, but significantly prolonged APD in the presence of isoproterenol in females. Apamin prolonged APD at the level of 25% repolarization (APD25) more prominently than APD at the level of 80% repolarization (APD80), consequently reversing isoproterenol‐induced AP triangulation in females. In comparison, apamin prolonged APD to a significantly lesser extent in males and failed to restore the AP plateau during isoproterenol infusion. IKAS in males did not respond to the L‐type calcium current agonist BayK8644, but was amplified by the casein kinase 2 (CK2) inhibitor 4,5,6,7‐tetrabromobenzotriazole. In addition, whole‐cell outward IKAS densities in ventricular cardiomyocytes were significantly larger in females than in males. SK channel subtype 2 (SK2) protein expression was higher and the CK2/SK2 ratio was lower in females than in males. IKAS activation in females induced negative intracellular Ca2+–voltage coupling, promoted electromechanically discordant phase 2 repolarization alternans and facilitated ventricular fibrillation (VF). Apamin eliminated the negative Ca2+–voltage coupling, attenuated alternans and reduced VF inducibility, phase singularities and dominant frequencies in females, but not in males. We conclude that β‐adrenergic stimulation activates ventricular IKAS in females to a much greater extent than in males. IKAS activation plays an important role in ventricular arrhythmogenesis in females during sympathetic stimulation
Amplifying the Music Listening Experience through Song Comments on Music Streaming Platforms
Music streaming services are increasingly popular among younger generations
who seek social experiences through personal expression and sharing of
subjective feelings in comments. However, such emotional aspects are often
ignored by current platforms, which affects the listeners' ability to find
music that triggers specific personal feelings. To address this gap, this study
proposes a novel approach that leverages deep learning methods to capture
contextual keywords, sentiments, and induced mechanisms from song comments. The
study augments a current music app with two features, including the
presentation of tags that best represent song comments and a novel map metaphor
that reorganizes song comments based on chronological order, content, and
sentiment. The effectiveness of the proposed approach is validated through a
usage scenario and a user study that demonstrate its capability to improve the
user experience of exploring songs and browsing comments of interest. This
study contributes to the advancement of music streaming services by providing a
more personalized and emotionally rich music experience for younger
generations.Comment: In the Proceedings of ChinaVis 202
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