arXiv subjects

Zhuo Cheng

Publications and source records attributed to Zhuo Cheng.

At least 19 recordsLinked to original sources

arXiv2026

SDSS-IV MaNGA: Star Formation Cessation in Low-redshift Galaxies. III. Dependence on Quenching Criteria

This paper is the third in a series of studies investigating star formation cessation in nearby galaxies on kiloparsec scales. Using the final SDSS-IV MaNGA data release, we ask how the inferred importance of global, local, and environmental properties depends on the operational definition of quenched regions. We classify spaxels as star-forming, reliably quenched, or potentially quenched by accounting for measurement uncertainties, and train random forest classifiers with a parameter set chosen for direct comparison with previous work. For reliably quenched regions, the local stellar mass surface density $\Sigma_\ast$ consistently has the highest feature importance, independent of quenching definition. By contrast, the high importance of central velocity dispersion $\sigma_c$, previously interpreted as evidence for galaxy-wide AGN feedback, is recovered mainly when potentially quenched regions are included. The leading parameter also varies with stellar mass: $\Sigma_{\rm 1kpc}$ is most important below $\sim10^{10.2}\,\textrm{M}_{\odot}$, whereas local quantities such as $\Sigma_\ast$ and $\sigma_\ast$ become more prominent at high masses. These results show that quenching criteria and uncertainty treatment can reconcile apparently discrepant feature-importance studies. AGN-related processes may contribute to ambiguous regions, but the reliably quenched population is most tightly linked to high local stellar density.

astro-ph.GA↗

arXiv2026

Mapping Dust Attenuation at Kiloparsec Scales. IV. A Dust-model Interpretation of Attenuation Curves in Nearby Galaxies

In this fourth paper on kiloparsec-scale dust attenuation, we ask whether the empirical trends found in Papers I--III can be translated into effective dust properties. Using attenuation curves for 2487 high-continuum-S/N spaxels in 91 SwiM v4.2 galaxies, we construct a grid of uniform-screen dust models composed of astronomical silicate and graphite grains with MRN-like size distributions. We fit the normalized attenuation-curve shape to constrain model parameters and then use the attenuation amplitude to estimate the model-dependent dust mass surface density. The inferred dust masses, compositions, and small-grain fractions are therefore effective quantities defined within the adopted attenuation model. The fitted models reproduce the main attenuation-curve variations and provide a direct bridge to Papers I--III: within this model, the relative 2175\AA\ bump sequence maps mainly onto the effective fraction of small graphitic/carbonaceous grains, while the NUV-slope sequence maps onto the effective small-silicate grain fraction and total silicate mass fraction. Non-SF regions have higher dust mass surface densities but lower dust-to-stellar mass ratios than SF regions, separating absolute dust content from dust content per unit stellar mass. Regions with larger specific H$\alpha$ surface brightness have larger dust-to-stellar mass ratios but lower inferred small-grain fractions, especially lower small-silicate fractions. In non-SF regions this quantity is interpreted as ionized-gas emission per unit stellar mass rather than as a direct sSFR. These model-dependent trends support a picture in which local dust processing changes the relative abundance of small grains and thereby shapes the attenuation-curve variations found across the series.

astro-ph.GA↗

arXiv2026

Mapping Dust Attenuation at Kiloparsec Scales. III. The 2175\AA\ Bump

We combine the SwiM_v4.2 Swift/UVOT+MaNGA catalog with 2MASS $K_s$ imaging to map the 2175{\AA} attenuation bump at kiloparsec scales in nearby galaxies. We use two complementary estimators: an ultraviolet-to-near-infrared attenuation-curve method, yielding $A_{bump}^{UOIR}$ and $B$ for 2487 high-continuum-S/N spaxels, and the NUV-only method of Battisti et al. (2025), yielding $A_{bump}^{NUV}$ and $k_{bump}$ for 7934 spaxels. The two absolute bump estimates agree well where they overlap. We compare bump strength with local stellar-population, emission-line, attenuation-curve, and geometric diagnostics after separating star-forming (SF) and non-SF regions. The strongest bumps occur at low specific H$\alpha$ surface brightness, $\Sigma_{\text{H}\alpha}/\Sigma_\ast$, especially in non-SF regions, where this ratio traces ionized-gas emission per unit stellar mass rather than sSFR. The bump also weakens with EW(H$\alpha$) and strengthens with $D_n4000$ and stellar age. In contrast, metallicity, inclination, galactocentric radius, $A_V$, and optical attenuation-curve slope are secondary predictors. The absolute strength $A_{bump}^{NUV}$ increases with $\Sigma_{\text{H}\alpha}$ and $\Sigma_\ast$, while the relative strengths $k_{bump}$ and $B$ do not, indicating that absolute bump amplitude partly follows dust column whereas normalized strengths better trace effective bump prominence. These results support local radiation-field processing of the 2175{\AA} carriers.

astro-ph.GA↗

arXiv2026

Post-starburst Galaxies with Active Galactic Nucleus: Properties and Evolutionary Sequences

Post-starburst (PSB) galaxies, identified by strong Balmer absorption and weak nebular emission, provide a key laboratory for studying rapid quenching. Using the final data release of the SDSS-IV MaNGA survey, we follow the traditional PSB selection criteria of Chen et al. (2019) and develop a new method to identify regions that simultaneously exhibit PSB features and nuclear activities (AGN-PSBs). Our final sample comprises 48 AGN-PSBs, 92 central PSBs (CPSBs), 89 ring-like PSBs (RPSBs), and 828 irregular PSBs (IPSBs). We find the global and spatially resolved properties of CPSBs and RPSBs are consistent with the results of Chen et al. (2019). In this work, we focus on the properties of AGN-PSBs, comparing them with CPSBs, RPSBs, and control galaxies. Similar to CPSBs and RPSBs, AGN-PSBs show positive $\mathrm{D}_{n}4000$ gradients relative to negative $\mathrm{D}_{n}4000$ gradients of their controls, which indicates younger stellar populations in the central region than that in the outskirt. Among the three sub-types, high-mass CPSBs (H-CPSBs, with $\log(M_{*}/M_{\odot})>9.5$) display the highest incidence of merger remnants and gas--star kinematic misalignment, consistent with a merger/interaction-dominated origin. AGN-PSBs and RPSBs, however, show lower and comparable fractions of merger remnants and gas--star kinematic misalignment, favoring less violent external mechanisms. Based on radial profiles of mass-weighted age and $V_{\rm star}/\sigma_{\rm star}$, we suggest that RPSBs can evolve into AGN-PSBs, whereas H-CPSBs likely follow a distinct evolutionary pathway. The existence of RPSBs and IPSBs also indicates that AGN feedback is not a necessary condition for the formation of PSB.

astro-ph.GA↗

arXiv2026

Monotonicity of the first nonzero Steklov eigenvalue of regular $N$-gon with fixed perimeter

We study the first nontrivial Steklov eigenvalue of perimeter-normalized regular $N$-gons and show that it is strictly increasing in $N$. The proof mainly relies on an analytic framework that establishes a refined asymptotic expansion in three steps: first, identifying the Steklov eigenvalue as the maximal eigenvalue of a Toeplitz-type operator; second, deriving the eigenvalue and its associated eigenfunctions simultaneously via Schur reduction; and finally, obtaining the exact coefficients in the Schur moment expansion by evaluating Euler-type sums. The monotonicity is proved to be eventual, holding for $N\ge 20$. For the remaining cases $3\le N\le 20$, we provide complementary computer-assisted verification, confirming monotonicity across the full range of $N$.

math.AP↗

arXiv2026

GenPairX: A Hardware-Algorithm Co-Designed Accelerator for Paired-End Read Mapping

Genome sequencing has become a central focus in computational biology. A genome study typically begins with sequencing, which produces millions to billions of short DNA fragments known as reads. Read mapping aligns these reads to a reference genome. Read mapping for short reads comes in two forms: single-end and paired-end, with the latter being more prevalent due to its higher accuracy and support for advanced analysis. Read mapping remains a major performance bottleneck in genome analysis due to expensive dynamic programming. Prior efforts have attempted to mitigate this cost by employing filters to identify and potentially discard computationally expensive matches and leveraging hardware accelerators to speed up the computations. While partially effective, these approaches have limitations. In particular, existing filters are often ineffective for paired-end reads, as they evaluate each read independently and exhibit relatively low filtering ratios. In this work, we propose GenPairX, a hardware-algorithm co-designed accelerator that efficiently minimizes the computational load of paired-end read mapping while enhancing the throughput of memory-intensive operations. GenPairX introduces: (1) a novel filtering algorithm that jointly considers both reads in a pair to improve filtering effectiveness, and a lightweight alignment algorithm to replace most of the computationally expensive dynamic programming operations, and (2) two specialized hardware mechanisms to support the proposed algorithms. Our evaluations show that GenPairX delivers substantial performance improvements over state-of-the-art solutions, achieving 1575x and 1.43x higher throughput per watt compared to leading CPU-based and accelerator-based read mappers, respectively, all without compromising accuracy.

cs.AR↗

arXiv2025

When Prompt Engineering Meets Software Engineering: CNL-P as Natural and Robust "APIs'' for Human-AI Interaction

With the growing capabilities of large language models (LLMs), they are increasingly applied in areas like intelligent customer service, code generation, and knowledge management. Natural language (NL) prompts act as the ``APIs'' for human-LLM interaction. To improve prompt quality, best practices for prompt engineering (PE) have been developed, including writing guidelines and templates. Building on this, we propose Controlled NL for Prompt (CNL-P), which not only incorporates PE best practices but also draws on key principles from software engineering (SE). CNL-P introduces precise grammar structures and strict semantic norms, further eliminating NL's ambiguity, allowing for a declarative but structured and accurate expression of user intent. This helps LLMs better interpret and execute the prompts, leading to more consistent and higher-quality outputs. We also introduce an NL2CNL-P conversion tool based on LLMs, enabling users to write prompts in NL, which are then transformed into CNL-P format, thus lowering the learning curve of CNL-P. In particular, we develop a linting tool that checks CNL-P prompts for syntactic and semantic accuracy, applying static analysis techniques to NL for the first time. Extensive experiments demonstrate that CNL-P enhances the quality of LLM responses through the novel and organic synergy of PE and SE. We believe that CNL-P can bridge the gap between emerging PE and traditional SE, laying the foundation for a new programming paradigm centered around NL.

cs.SE↗

arXiv2025

HSSBench: Benchmarking Humanities and Social Sciences Ability for Multimodal Large Language Models

Multimodal Large Language Models (MLLMs) have demonstrated significant potential to advance a broad range of domains. However, current benchmarks for evaluating MLLMs primarily emphasize general knowledge and vertical step-by-step reasoning typical of STEM disciplines, while overlooking the distinct needs and potential of the Humanities and Social Sciences (HSS). Tasks in the HSS domain require more horizontal, interdisciplinary thinking and a deep integration of knowledge across related fields, which presents unique challenges for MLLMs, particularly in linking abstract concepts with corresponding visual representations. Addressing this gap, we present HSSBench, a dedicated benchmark designed to assess the capabilities of MLLMs on HSS tasks in multiple languages, including the six official languages of the United Nations. We also introduce a novel data generation pipeline tailored for HSS scenarios, in which multiple domain experts and automated agents collaborate to generate and iteratively refine each sample. HSSBench contains over 13,000 meticulously designed samples, covering six key categories. We benchmark more than 20 mainstream MLLMs on HSSBench and demonstrate that it poses significant challenges even for state-of-the-art models. We hope that this benchmark will inspire further research into enhancing the cross-disciplinary reasoning abilities of MLLMs, especially their capacity to internalize and connect knowledge across fields.

cs.CL↗

arXiv2025

Mapping Dust Attenuation at Kiloparsec Scales. II. Attenuation Curves from Near-Ultraviolet to Near-Infrared

This is the second paper in a series that utilize IFS from MaNGA, NUV imaging from Swift/UVOT and NIR imaging from 2MASS to study dust attenuation properties on kpc scales in nearby galaxies. We apply the method developed in Paper I (Zhou et al. 2023) to the updated SWiM_v4.2 catalog, and measure the optical attenuation curve and the attenuation in three NUV bands for 2487 spaxels selected from 91 galaxies with S/N>20 and $A_V$>0.25. We classify all spaxels into two subsets: star-forming (SF) regions and non-SF regions. We explore the correlations of optical opacity ($A_V$) and the optical and NUV slopes of attenuation curves ($A_B/A_V$ and $A_{w2}/A_{w1}$) with a broad range of stellar and emission-line properties, including specific surface brightness of H$\alpha$ emission, stellar age, stellar and gas-phase metallicity, and diagnostics of recent star formation history. When comparing SF and non-SF regions, we find that $A_V$ and $A_B/A_V$ exhibit similar correlations with all the stellar population and emission-line properties considered, while the NUV slopes in SF regions tend to be flatter than those in non-SF regions. The NUV slope $A_{w2}/A_{w1}$ exhibits an anti-correlation with specific surface brightness of H$\alpha$ emission, a trend that is primarily driven by the positive correlation between $A_{w2}/A_{w1}$ and $\Sigma_\ast$. The NUV slope flattens in SF regions that contain young stellar populations and have experienced recent star formation, but it shows no obvious dependence on stellar or gas-phase metallicity. The spatially resolved dust attenuation properties exhibit no clear correlations with the inclination of host galaxies or the galactocentric distance of the regions. This finding reinforces the conclusion from Paper I that dust attenuation is primarily regulated by local processes on kpc scales or smaller, rather than by global processes at galactic scales.

astro-ph.GA↗

arXiv2025

Nanosatellite Constellation and Ground Station Co-design for Low-Latency Critical Event Detection

Advancements in nanosatellite technology lead to more Earth-observation satellites in low-Earth orbit. We explore using nanosatellite constellations to achieve low-latency detection for time-critical events, such as forest fires, oil spills, and floods. The detection latency comprises three parts: capture, compute and transmission. Previous solutions reduce transmission latency, but we find that the bottleneck is capture latency, accounting for more than 90% of end-to-end latency. We present a measurement study on how various satellite and ground station design factors affect latency. We offer design guidance to operators on how to choose satellite orbital configurations and design an algorithm to choose ground station locations. For six use cases, our design guidance reduces end-to-end latency by 5.6 to 8.2 times compared to the existing system.

cs.ET↗

arXiv2024

New constraints on Triton's atmosphere from the 6 October 2022 stellar occultation

The atmosphere of Triton was probed directly by observing a ground-based stellar occultation on 6 October 2022. This rare event yielded 23 positive light curves collected from 13 separate observation stations contributing to our campaign. The significance of this event lies in its potential to directly validate the modest pressure fluctuation on Triton, a phenomenon not definitively verified by previous observations, including only five stellar occultations, and the Voyager 2 radio occultation in 1989. Using an approach consistent with a comparable study, we precisely determined a surface pressure of $14.07_{-0.13}^{+0.21}~\mathrm{\mu bar}$ in 2022. This new pressure rules out any significant monotonic variation in pressure between 2017 and 2022 through direct observations, as it is in alignment with the 2017 value. Additionally, both the pressures in 2017 and 2022 align with the 1989 value. This provides further support for the conclusion drawn from the previous volatile transport model simulation, which is consistent with the observed alignment between the pressures in 1989 and 2017; that is to say, the pressure fluctuation is modest. Moreover, this conclusion suggests the existence of a northern polar cap extended down to at least $45^\circ$N$-60^\circ$N and the presence of nitrogen between $30^\circ$S and $0^\circ$.

astro-ph.EP↗

arXiv2023

Post-starburst galaxies in SDSS-IV MaNGA: Two broad categories of evolutionary pathways

We study the size-mass relation (SMR) and recent star formation history (SFH) of post-starburst (PSB) galaxies in the local Universe, using spatially resolved spectroscopy from the final data release of MaNGA. Our sample includes 489 PSB galaxies: 94 cPSB galaxies with central PSB regions, 85 rPSB galaxies with ring-like PSB regions and 310 iPSB galaxies with irregular PSB regions. When compared to control galaxies of similar SFR, redshift and mass, a similar SMR is found for all types of PSB samples except the cPSB galaxies which have smaller sizes at intermediate masses ($9.5\lesssim \log_{10}(\rm M_\ast/M_\odot)\lesssim 10.5$). The iPSB galaxies in the star-forming sequence (iPSB-SF) show no/weak gradients in $\textrm{D}_{n}(4000)$, $\textrm{EW}(\textrm{H}\delta_{A})$ and $\textrm{EW}(\textrm{H}\alpha)$, consistent with the global star-forming status of this type of galaxies, while the quiescent iPSB (iPSB-Q) sample shows negative gradients in $\textrm{D}_{n}(4000)$ and positive gradients in $\textrm{EW}(\textrm{H}\delta_{A})$, indicating older stellar populations in the inner regions. Both cPSB and rPSB samples show positive gradients in $\textrm{D}_{n}(4000)$ and negative gradients in $\textrm{EW}(\textrm{H}\delta_{A})$, indicating younger stellar populations in the inner regions. These results imply that the four types of PSB galaxies can be broadly divided into two distinct categories in terms of evolutionary pathway: (1) iPSB-SF and iPSB-Q which have SMRs and SFHs similar to control galaxies, preferring an inside-out quenching process, (2) rPSB and cPSB which appear to be different stages of the same event, likely to follow the outside-in quenching process driven by disruption events such as mergers that result in a more compact structure as quenching proceeds.

astro-ph.GA↗

arXiv2022

Mapping dust attenuation and the 2175 {\AA} bump at kpc scales in nearby galaxies

We develop a novel approach to measure dust attenuation properties of galaxies, including the dust opacity, shape of the attenuation curve and the strength of the 2175{\AA} absorption feature. From an observed spectrum, the method uses a model-independent approach to derive a relative attenuation curve, with absolute amplitude calibrated using NIR photometry. The dust-corrected spectrum is fitted with stellar population models to derive the dust-free model spectrum, which is compared with the observed SED/spectrum from NUV to NIR to determine dust attenuation properties. We apply this method to investigate dust attenuation on kpc scales, using a sample of 134 galaxies with integral field spectroscopy from MaNGA, NIR imaging from 2MASS, and NUV imaging from Swift/UVOT. We find the attenuation curve slope and the 2175{\AA} bump in both optical and NUV span a wide range at kpc scales. The slope is shallower at higher optical opacity, regardless of the specific star formation rate (sSFR), minor-to-major axis ratio (b/a) of galaxies and the location of spaxels within individual galaxies. The 2175{\AA} bump presents a strong negative correlation with the sSFR, while the correlations with the optical opacity, b/a and the location within individual galaxies are all weak. All these trends appear to be independent of the stellar mass of galaxies. Our results support the scenario that the variation of the 2175{\AA} bump is driven predominantly by processes related to star formation, such as the destruction of small dust grains by UV radiation in star-forming regions.

astro-ph.GA↗

arXiv2022

Enabling Efficient and General Subpopulation Analytics in Multidimensional Data Streams

Today's large-scale services (e.g., video streaming platforms, data centers, sensor grids) need diverse real-time summary statistics across multiple subpopulations of multidimensional datasets. However, state-of-the-art frameworks do not offer general and accurate analytics in real time at reasonable costs. The root cause is the combinatorial explosion of data subpopulations and the diversity of summary statistics we need to monitor simultaneously. We present Hydra, an efficient framework for multidimensional analytics that presents a novel combination of using a ``sketch of sketches'' to avoid the overhead of monitoring exponentially-many subpopulations and universal sketching to ensure accurate estimates for multiple statistics. We build Hydra as an Apache Spark plugin and address practical system challenges to minimize overheads at scale. Across multiple real-world and synthetic multidimensional datasets, we show that Hydra can achieve robust error bounds and is an order of magnitude more efficient in terms of operational cost and memory footprint than existing frameworks (e.g., Spark, Druid) while ensuring interactive estimation times.

cs.DB↗

arXiv2022

LQoCo: Learning to Optimize Cache Capacity Overloading in Storage Systems

Cache plays an important role to maintain high and stable performance (i.e. high throughput, low tail latency and throughput jitter) in storage systems. Existing rule-based cache management methods, coupled with engineers' manual configurations, cannot meet ever-growing requirements of both time-varying workloads and complex storage systems, leading to frequent cache overloading. In this paper, we for the first time propose a light-weight learning-based cache bandwidth control technique, called \LQoCo which can adaptively control the cache bandwidth so as to effectively prevent cache overloading in storage systems. Extensive experiments with various workloads on real systems show that LQoCo, with its strong adaptability and fast learning ability, can adapt to various workloads to effectively control cache bandwidth, thereby significantly improving the storage performance (e.g. increasing the throughput by 10\%-20\% and reducing the throughput jitter and tail latency by 2X-6X and 1.5X-4X, respectively, compared with two representative rule-based methods).

cs.AR↗

arXiv2020

Learning to Plan and Realize Separately for Open-Ended Dialogue Systems

Achieving true human-like ability to conduct a conversation remains an elusive goal for open-ended dialogue systems. We posit this is because extant approaches towards natural language generation (NLG) are typically construed as end-to-end architectures that do not adequately model human generation processes. To investigate, we decouple generation into two separate phases: planning and realization. In the planning phase, we train two planners to generate plans for response utterances. The realization phase uses response plans to produce an appropriate response. Through rigorous evaluations, both automated and human, we demonstrate that decoupling the process into planning and realization performs better than an end-to-end approach.

cs.CL↗

arXiv2020

The Panacea Threat Intelligence and Active Defense Platform

We describe Panacea, a system that supports natural language processing (NLP) components for active defenses against social engineering attacks. We deploy a pipeline of human language technology, including Ask and Framing Detection, Named Entity Recognition, Dialogue Engineering, and Stylometry. Panacea processes modern message formats through a plug-in architecture to accommodate innovative approaches for message analysis, knowledge representation and dialogue generation. The novelty of the Panacea system is that uses NLP for cyber defense and engages the attacker using bots to elicit evidence to attribute to the attacker and to waste the attacker's time and resources.

cs.CL↗

arXiv2020

Detecting Asks in SE attacks: Impact of Linguistic and Structural Knowledge

Social engineers attempt to manipulate users into undertaking actions such as downloading malware by clicking links or providing access to money or sensitive information. Natural language processing, computational sociolinguistics, and media-specific structural clues provide a means for detecting both the ask (e.g., buy gift card) and the risk/reward implied by the ask, which we call framing (e.g., lose your job, get a raise). We apply linguistic resources such as Lexical Conceptual Structure to tackle ask detection and also leverage structural clues such as links and their proximity to identified asks to improve confidence in our results. Our experiments indicate that the performance of ask detection, framing detection, and identification of the top ask is improved by linguistically motivated classes coupled with structural clues such as links. Our approach is implemented in a system that informs users about social engineering risk situations.

cs.CL↗