skip to main content

Search for: All records

Creators/Authors contains: "Wang, R."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Free, publicly-accessible full text available June 1, 2023
  2. Free, publicly-accessible full text available November 1, 2022
  3. The success of authorship attribution relies on the presence of linguistic features specific to individual authors. There is, however, limited research assessing to what extent authorial style remains constant when individuals switch from one writing modality to another. We measure the effect of writing mode on writing style in the context of authorship attribution research using a corpus of documents composed online (in a web browser) and documents composed offline using a traditional word processor. The results confirm the existence of a “mode effect” on authorial style. Online writing differs systematically from offline writing in terms of sentence length, wordmore »use, readability, and certain part-of-speech ratios. These findings have implications for research design and feature engineering in authorship attribution studies.« less
  4. We consider the problem of velocity inversion/calibration in passive survey, where the seismic source is also an unknown. In earthquake detection or microseismic localization, the major task is to reconstruct the passive seismic sources, but due to the source-velocity coupling, source reconstructions are inherently affected by inaccurate knowledge of the velocity, bringing the need of velocity calibration. We propose a source independent velocity calibration method that recovers the velocity without the source information, thus providing a better ground for source inversion. Unlike existing methods that assume sources to be a linear combination of separated point sources, the proposed method allowsmore »sources to lie on a line singularity (representing rock cracks), as long as the activation time is relatively brief. The proposed approach is based on the observation that the spatial distribution of the source is separable from the velocity model after a proper Helmholtz domain projection.« less
  5. null (Ed.)
    Free, publicly-accessible full text available July 1, 2022
  6. We present a multiline survey of the interstellar medium (ISM) in two z  > 6 quasar host galaxies, PJ231−20 ( z  = 6.59) and PJ308−21 ( z  = 6.23), and their two companion galaxies. Observations were carried out using the Atacama Large (sub-)Millimeter Array (ALMA). We targeted 11 transitions including atomic fine-structure lines (FSLs) and molecular lines: [NII] 205 μm , [CI] 369 μm , CO ( J up  = 7, 10, 15, 16), H 2 O 3 12  − 2 21 , 3 21  − 3 12 , 3 03  − 2 12 , and the OH 163 μm doublet. The underlying far-infrared (FIR) continuum samples the Rayleigh-Jeans tail of the respectivemore »dust emission. By combining this information with our earlier ALMA [CII] 158 μm observations, we explored the effects of star formation and black hole feedback on the ISM of the galaxies using the CLOUDY radiative transfer models. We estimated dust masses, spectral indexes, IR luminosities, and star-formation rates from the FIR continuum. The analysis of the FSLs indicates that the [CII] 158 μm and [CI] 369 μm emission arises predominantly from the neutral medium in photodissociation regions (PDRs). We find that line deficits agree with those of local luminous IR galaxies. The CO spectral line energy distributions (SLEDs) reveal significant high- J CO excitation in both quasar hosts. Our CO SLED modeling of the quasar PJ231−20 shows that PDRs dominate the molecular mass and CO luminosities for J up  ≤ 7, while the J up  ≥ 10 CO emission is likely driven by X-ray dissociation regions produced by the active galactic nucleus (AGN) at the very center of the quasar host. The J up  > 10 lines are undetected in the other galaxies in our study. The H 2 O 3 21  − 3 12 line detection in the same quasar places this object on the L H 2 O  −  L TIR relation found for low- z sources, thus suggesting that this water vapor transition is predominantly excited by IR pumping. Models of the H 2 O SLED and of the H 2 O-to-OH 163 μm ratio point to PDR contributions with high volume and column density ( n H  ∼ 0.8 × 10 5 cm −3 , N H  = 10 24 cm −2 ) in an intense radiation field. Our analysis suggests a less highly excited medium in the companion galaxies. However, the current data do not allow us to definitively rule out an AGN in these sources, as suggested by previous studies of the same objects. This work demonstrates the power of multiline studies of FIR diagnostics in order to dissect the physical conditions in the first massive galaxies emerging from cosmic dawn.« less
    Free, publicly-accessible full text available August 1, 2022