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Yun Huang

Publications and source records attributed to Yun Huang.

52 records · Page 3Linked to original sources

Discovering the Hidden Facts of User-Dispatcher Interactions via Text-based Reporting Systems for Community Safety

Recently, an increasing number of safety organizations in the U.S. have incorporated text-based risk reporting systems to respond to safety incident reports from their community members. To gain a better understanding of the interaction between community members and dispatchers using text-based risk reporting systems, this study conducts a system log analysis of LiveSafe, a community safety reporting system, to provide empirical evidence of the conversational patterns between users and dispatchers using both quantitative and qualitative methods. We created an ontology to capture information (e.g., location, attacker, target, weapon, start-time, and end-time, etc.) that dispatchers often collected from users regarding their incident tips. Applying the proposed ontology, we found that dispatchers often asked users for different information across varied event types (e.g., Attacker for Abuse and Attack events, Target for Harassment events). Additionally, using emotion detection and regression analysis, we found an inconsistency in dispatchers' emotional support and responsiveness to users' messages between different organizations and between incident categories. The results also showed that users had a higher response rate and responded quicker when dispatchers provided emotional support. These novel findings brought significant insights to both practitioners and system designers, e.g., AI-based solutions to augment human agents' skills for improved service quality.

cs.HC↗

Evaluating Lya Emission as a Tracer of the Largest Cosmic Structure at z~2.47

The discovery and spectroscopic confirmation of Hyperion, a proto-supercluster at z~2.47, provides an unprecedented opportunity to study distant galaxies in the context of their large-scale environment. We carry out deep narrow-band imaging of a ~1*1 deg^2 region around Hyperion and select 157 Lya emitters (LAEs). The inferred LAE overdensity is delta_g~40 within an effective volume of 30*20*15 cMpc^3, consistent with the fact that Hyperion is composed of multiple protoclusters and will evolve into a super-cluster with a total mass of M_tot ~1.4*10^15 M_sun at z=0. The distribution of LAEs closely mirrors that of known spectroscopic members, tracing the protocluster cores and extended filamentary arms connected to them, suggesting that they trace the same large-scale structure. By cross-correlating the LAE positions with HI tomography data, we find weak evidence that LAEs may be less abundant in the highest HI regions, perhaps because Lya is suppressed in such regions. The Hyperion region hosts a large population of active galactic nuclei (AGN), ~12 times more abundant than that in the field. The prevalence of AGN in protocluster regions hints at the possibility that they may be triggered by physical processes that occur more frequently in dense environments, such as galaxy mergers. Our study demonstrates LAEs as reliable markers of the largest cosmic structures. When combined with ongoing and upcoming imaging and spectroscopic surveys, wide-field narrow-band imaging has the potential to advance our knowledge in the formation and evolution of cosmic structures and of their galaxy inhabitants.

astro-ph.GA↗

Facing the Illusion and Reality of Safety in Social VR

The ethical design of social Virtual Reality (VR) is not a new topic, but "safety" concerns of using social VR are escalated to a different level given the heat of the Metaverse. For example, it was reported that nearly half of the female-identifying VR participants have had at least one instance of virtual sexual harassment. Feeling safe is a basic human right - in any place, regardless in real or virtual spaces. In this paper, we are seeking to understand the discrepancy between user concerns and designs in protecting user safety in social VR applications. We study safety concerns on social VR experience first by analyzing Twitter posts and then synthesize practices on safety protection adopted by four mainstream social VR platforms. We argue that future research and platforms should explore the design of social VR with boundary-awareness.

cs.HC↗

UX Research on Conversational Human-AI Interaction: A Literature Review of the ACM Digital Library

Early conversational agents (CAs) focused on dyadic human-AI interaction between humans and the CAs, followed by the increasing popularity of polyadic human-AI interaction, in which CAs are designed to mediate human-human interactions. CAs for polyadic interactions are unique because they encompass hybrid social interactions, i.e., human-CA, human-to-human, and human-to-group behaviors. However, research on polyadic CAs is scattered across different fields, making it challenging to identify, compare, and accumulate existing knowledge. To promote the future design of CA systems, we conducted a literature review of ACM publications and identified a set of works that conducted UX (user experience) research. We qualitatively synthesized the effects of polyadic CAs into four aspects of human-human interactions, i.e., communication, engagement, connection, and relationship maintenance. Through a mixed-method analysis of the selected polyadic and dyadic CA studies, we developed a suite of evaluation measurements on the effects. Our findings show that designing with social boundaries, such as privacy, disclosure, and identification, is crucial for ethical polyadic CAs. Future research should also advance usability testing methods and trust-building guidelines for conversational AI.

cs.HC↗

"It's A Blessing and A Curse": Unpacking Creators' Practices with Non-Fungible Tokens (NFTs) and Their Communities

NFTs (Non-Fungible Tokens) are blockchain-based cryptographic tokens to represent ownership of unique content such as images, videos, or 3D objects. Despite NFTs' increasing popularity and skyrocketing trading prices, little is known about people's perceptions of and experiences with NFTs. In this work, we focus on NFT creators and present results of an exploratory qualitative study in which we interviewed 15 NFT creators from nine different countries. Our participants had nuanced feelings about NFTs and their communities. We found that most of our participants were enthusiastic about the underlying technologies and how they empower individuals to express their creativity and pursue new business models of content creation. Our participants also gave kudos to the NFT communities that have supported them to learn, collaborate, and grow in their NFT endeavors. However, these positivities were juxtaposed by their accounts of the many challenges that they encountered and thorny issues that the NFT ecosystem is grappling with around ownership of digital content, low-quality NFTs, scams, possible money laundering, and regulations. We discuss how the built-in properties (e.g., decentralization) of blockchains and NFTs might have contributed to some of these issues. We present design implications on how to improve the NFT ecosystem (e.g., making NFTs even more accessible to newcomers and the broader population).

cs.CY↗

Lyman Alpha line properties at $z \simeq 3.78$ and their environmental dependence: a case study around a massive proto-cluster

Ly$α$-emitting galaxies (LAEs) are easily detectable in the high-redshift Universe and are potentially efficient tracers of large scale structure at early epochs, as long as their observed properties do not strongly depend on environment. We investigate the luminosity and equivalent width functions of LAEs in the overdense field of a protocluster at redshift $z \simeq 3.78$. Using a large sample of LAEs (many spectroscopically confirmed), we find that the Ly$α$ luminosity distribution is well-represented by a Schechter (1976) function with $\log(L^{\ast}/{\rm erg s^{-1}}) = 43.26^{+0.20}_{-0.22}$ and $\log(ϕ^{\ast}/{\rm Mpc^{-3}})=-3.40^{+0.03}_{-0.04}$ with $α=-1.5$. Fitting the equivalent width distribution as an exponential, we find a scale factor of $ω=79^{+15}_{-15}$ Angstroms. We also measured the Ly$α$ luminosity and equivalent width functions using the subset of LAEs lying within the densest cores of the protocluster, finding similar values for $L^*$ and $ω$. Hence, despite having a mean overdensity more than 2$\times$ that of the general field, the shape of the Ly$α$ luminosity function and equivalent width distributions in the protocluster region are comparable to those measured in the field LAE population by other studies at similar redshift. While the observed Ly$α$ luminosities and equivalent widths show correlations with the UV continuum luminosity in this LAE sample, we find that these are likely due to selection biases and are consistent with no intrinsic correlations within the sample. This protocluster sample supports the strong evolutionary trend observed in the Ly$α$ escape fraction and suggest that lower redshift LAEs can be on average significantly more dusty that their counterparts at higher redshift.

astro-ph.GA↗

The Role of Dust, UV Luminosity and Large-scale Environment on the Escape of Lya Photons: A Case Study of a Protocluster field at z = 3.1

We present a detailed characterization of the Lya properties for 93 Lya emitters (LAEs) at z~3.1 selected from the D1 field of the Canada-France-Hawaii-Telescope Legacy Survey, including 24 members of a massive protocluster. The median-stacked Lya image shows an extended Lya halo (LAH) surrounding the galaxy with the exponential scale length 4.9+/-0.7kpc, which accounts for roughly half of the total line flux. Accounting for the LAH contribution, the total Lya escape fraction, f_esc, is 40+/-26%. Combining the dataset with existing measurements, we find a dependence of f_esc on the galaxy's UV slope (beta) and UV luminosity (L_UV). The simultaneous use of both parameters allows prediction of f_esc within 0.18dex, a substantial improvement over 0.23dex when only beta is used. The correlation between f_esc and E(B-V) suggests that Lya photons undergo interstellar dust attenuation in a similar manner to continuum photons. Yet, Lya transmission is typically higher than that expected for continuum photons at similar wavelength by a factor, which depends on UV luminosity, up to 2 in the samples we studied. These results hint at complex geometries and physical conditions of the interstellar medium, which affect the Lya transmission or production. Alternatively, the dust law may change with luminosity leading to over-or under-estimation of f_esc. Finally, we report that protocluster member LAEs tend to be bluer and more UV-luminous than their field cousins, resulting in systematically higher f_esc values. We speculate that it may be due to the widespread formation of young low-mass galaxies in dense gas-rich environments.

astro-ph.GA↗

Reproducing kernels of some weighted Bergman spaces

Herein, the theory of Bergman kernel is developed to the weighted case. A general form of weighted Bergman reproducing kernel is obtained, by which we can calculate concrete Bergman kernel functions for specific weights and domains.

math.CV↗

Measuring the total infrared light from galaxy clusters at z=0.5-1.6: connecting stellar populations to dusty star formation

Massive galaxy clusters undergo strong evolution from z~1.6 to z~0.5, with overdense environments at high-z characterized by abundant dust-obscured star formation and stellar mass growth which rapidly give way to widespread quenching. Data spanning the near- to far-infrared (IR) spectrum can directly trace this transformation; however, such studies have largely been limited to the massive galaxy end of cluster populations. In this work, we present ``total light" stacking techniques spanning 3.4-500μm aimed at revealing the total cluster IR emission, including low mass members and potential intracluster dust. We detail our procedures for WISE, Spitzer, and Herschel imaging, including corrections to recover the total stacked emission in the case of high fractions of detected galaxies. We apply our stacking techniques to 232 well-studied massive (log M200/Msun~13.8) clusters across multiple z bins, recovering extended cluster emission at all wavelengths, typically at >5sigma. We measure the averaged near- to far-IR radial profiles and SEDs, quantifying the total stellar and dust content. The near-IR radial profiles are well described by an NFW model with a high (c~7) concentration parameter. Dust emission is similarly concentrated, albeit suppressed at small radii (r<0.2Mpc). The measured SEDs lack warm dust, consistent with the colder SEDs expected for low mass galaxies. We derive total stellar masses consistent with the theoretical Mhalo-M_star relation and specific-star formation rates that evolve strongly with redshift, echoing that of massive (log Mstar/Msun>10) cluster galaxies. Separating out the massive galaxy population reveals that the majority of cluster far-IR emission (~70-80%) is provided by the low mass constituents, which differs from field galaxies. This effect may be a combination of mass-dependent quenching and excess dust in low mass cluster galaxies.

astro-ph.GA↗

Nuclear mass parabola and its applications

We propose a method to extract the properties of the isobaric mass parabola based on the total double $β$ decay energies of isobaric nuclei. Two important parameters of the mass parabola, the location of the most $β$-stable nuclei $Z_{A}$ and the curvature parameter $b_{A}$, are obtained for 251 A values based on the total double $β$ decay energies of nuclei compiled in AME2016 database.The advantage of this approach is that we can remove the pairing energy term $P_{A}$ caused by odd-even variation, and the mass excess $M(A,Z_{A})$ of the most stable nuclide for mass number $A$ in the performance process, which are used in the mass parabolic fitting method. The Coulomb energy coefficient $a_{c}=0.6910$ MeV is determined by the mass difference relation of mirror nuclei, and the symmetry energy coefficient is also studied by the relation $a_{\rm sym}(A)=0.25b_{A}Z_{A}$.

nucl-th↗

How Do Galaxies trace a large scale structure?: A case study around a massive protocluster at $z=3.13$

In the hierarchical theory of galaxy formation, a galaxy overdensity is a hallmark of a massive cosmic structure. However, it is less well understood how different types of galaxies trace the underlying large-scale structure. Motivated by the discovery of a z=3.13 protocluster, we examine how the same structure is populated by Ly$α$-emitting galaxies (LAEs). To this end, we have undertaken a deep narrow-band imaging survey sampling Ly$α$ emission at this redshift. Of the 93 LAE candidates within a 36'x36'~(70x70~Mpc^2) field, 21 galaxies form a significant surface overdensity (delta_g=3.3+/-0.9), which is spatially segregated from the Lyman break galaxy (LBG) overdensity. One possible interpretation is that they trace two separate structures of comparable masses (~ 10^{15}M_sun) where the latter is hosted by a halo assembled at an earlier time. We speculate that the dearth of LAEs in the LBG overdensity region may signal the role of halo assembly bias in galaxy formation, which would suggest that different search techniques may be biased accordingly to the formation age or dynamical state of the host halo. The median Ly$α$- and UV luminosity is 30--70\% higher for the protocluster LAEs relative to the field. This difference cannot be explained by the galaxy overdensity alone, and may require a top-heavy mass function, higher star formation efficiency for protocluster halos, or suppression of galaxy formation in low-mass halos. A luminous Ly$α$ blob and an ultramassive galaxy found in this region paint a picture consistent with the expected early growth of galaxies in clusters.

astro-ph.GA↗

A census of galaxy constituents in a Coma Progenitor observed at z>3

We present a detailed census of galaxies in and around PC217.96+32.3, a spectroscopically confirmed Coma analog at z=3.78. Diverse galaxy types identified in the field include Lya emitters (LAEs), massive star-forming galaxies, and ultra-massive galaxies (log (Mstar/Msun)>= 11) which may have already halted their star formation. The sky distribution of the star-forming galaxies suggests the presence of a significant overdensity (delta_g=8+/-2), which is spatially offset from the previously confirmed members by 3-4 Mpc to the west. Candidate quiescent and post-starburst galaxies are also found in large excess (a factor of ~ 8-15 higher surface density than the field) although their redshifts are less certain. We estimate that the total enclosed mass traced by star-forming galaxy candidates is roughly comparable to that of PC217.96+32.3 traced by the LAEs. We speculate that the true extent of PC217.96+32.3 may be larger than previously known, a half of which is missed by our LAE selection. Alternatively, the newly discovered overdensity may belong to another Coma progenitor not associated with PC217.96+32.3. Expectations from theory suggest that both scenarios are equally unlikely (<1%), particularly in the cosmic volume probed in our survey. If confirmed as a single structure, its total mass will be well in excess of Coma, making this a singularly large cosmic structure rarely seen even in large cosmological simulations. Finally, we find that the protocluster galaxies follow the same SFR-M_star scaling relation as the field galaxies, suggesting that the environmental effect at z~4 is a subtle one at best for normal star-forming galaxies.

astro-ph.GA↗

Discovery of a Very Large (~20 kpc) Galaxy at z=3.72

We report the discovery and spectroscopic confirmation of a very large star-forming Lyman Break galaxy, G6025, at z_spec=3.721+/-0.003. In the rest-frame ~2100A, G6025 subtends ~24 kpc in physical extent when measured from the 1.5-sigma isophote, in agreement with the parametric size measurements which yield the half-light radius of 4.9+/-0.5 kpc and the semi-major axis of 12.5+/-0.1 kpc. G6025 is also very UV-luminous (~5L*(z~4}) and young (~140+/-60 Myr). Despite its unusual size and luminosity, the stellar population parameters and dust reddening (M_star~M*(z~4)$, and E(B-V)=0.18+/-0.05) estimated from the integrated light, are similar to those of smaller galaxies at comparable redshifts. The ground-based morphology and spectroscopy show two dominant components, both located off-center, embedded in more diffuse emission. We speculate that G6025 may be a scaled-up version of chain galaxies seen in deep HST imaging, or alternatively, a nearly equal-mass merger involving two super-L* galaxies in its early stage. G6025 lies close to but not within a known massive protocluster at z=3.78. We find four companions within 6 Mpc from G6025, two of which lie within 1.6 Mpc. While the limited sensitivity of the existing spectroscopy does not allow us to robustly characterize the local environment of G6025, it likely resides in a locally overdense environment. The luminosity, size, and youth of G6025 make it uniquely suited to study the early formation of massive galaxies in the universe.

astro-ph.GA↗

Low-Rank Kernel Matrix Approximation Using Skeletonized Interpolation With Endo- or Exo-Vertices

The efficient compression of kernel matrices, for instance the off-diagonal blocks of discretized integral equations, is a crucial step in many algorithms. In this paper, we study the application of Skeletonized Interpolation to construct such factorizations. In particular, we study four different strategies for selecting the initial candidate pivots of the algorithm: Chebyshev grids, points on a sphere, maximally-dispersed and random vertices. Among them, the first two introduce new interpolation points (exo-vertices) while the last two are subsets of the given clusters (endo- vertices). We perform experiments using three real-world problems coming from the multiphysics code LS-DYNA. The pivot selection strategies are compared in term of quality (final rank) and efficiency (size of the initial grid). These benchmarks demonstrate that overall, maximally-dispersed vertices provide an accurate and efficient sets of pivots for most applications. It allows to reach near-optimal ranks while starting with relatively small sets of vertices, compared to other strategies.

math.NA↗

MoS2/C @ Polyurethane Composite Sponges for Synergistic High-Rate Solar Steaming and Mercury Removal

Solar steam generation, a sustainable water-purification technology, holds substantial promises in resolving the global issue of shortage of drinkable water. Here, we report the design, fabrication, and performance of an innovative three-dimensional (3-D) solar steamer, offering synergistic high-rate steaming and heavy metal removal functions. The device is made of synthesized carbon-molybdenum-disulfide microbeads electrostatically assembled on a 3-D polyurethane sponge. The mesoporous composite sponge also serves as a freestanding water reservoir that avoids one-side contact to bulk water, effectively suppressing the commonly observed parasitic heat loss, and offering a high energy efficiency of 88%. When being sculptured into a 3-D spoke-like structure, the composite sponge achieves one of the highest evaporation rates of 1.95 kg m-2 h-1 at 1 sun. The solar steamer is demonstrated for water treatment, i.e. decontamination of metal ions, disinfection, and reducing alkalinity and hardness of river water. Particularly, the strong mercury adsorption of MoS2 reduces Mercury from 200 to 1ppb, meeting the stringent standard set by the Environmental Protection Agency, which is the first demonstration of mercury-removal powered by solar energy. The unique design, fabrication, water-handling strategy, and mercury-removal function of this high-performance solar steamer could inspire new paradigms of water treatment technologies.

physics.app-ph↗