392 research outputs found
Spectral Line De-confusion in an Intensity Mapping Survey
Spectral line intensity mapping has been proposed as a promising tool to
efficiently probe the cosmic reionization and the large-scale structure.
Without detecting individual sources, line intensity mapping makes use of all
available photons and measures the integrated light in the source confusion
limit, to efficiently map the three-dimensional matter distribution on large
scales as traced by a given emission line. One particular challenge is the
separation of desired signals from astrophysical continuum foregrounds and line
interlopers. Here we present a technique to extract large-scale structure
information traced by emission lines from different redshifts, embedded in a
three-dimensional intensity mapping data cube. The line redshifts are
distinguished by the anisotropic shape of the power spectra when projected onto
a common coordinate frame. We consider the case where high-redshift [CII] lines
are confused with multiple low-redshift CO rotational lines. We present a
semi-analytic model for [CII] and CO line estimates based on the cosmic
infrared background measurements, and show that with a modest instrumental
noise level and survey geometry, the large-scale [CII] and CO power spectrum
amplitudes can be successfully extracted from a confusion-limited data set,
without external information. We discuss the implications and limits of this
technique for possible line intensity mapping experiments.Comment: 13 pages, 14 figures, accepted by Ap
Is the Radio Source Dipole from NVSS Consistent with the CMB and CDM?
The dipole moment in the angular distribution of the cosmic microwave
background (CMB) is thought to originate from the Doppler Effect and our motion
relative to the CMB frame. Observations of large-scale structure (LSS) should
show a related "kinematic dipole" and help test the kinematic origin of the CMB
dipole. Intriguingly, many previous LSS dipole studies suggest discrepancies
with the expectations from the CMB. Here we reassess the apparent inconsistency
between the CMB measurements and dipole estimates from the NVSS catalog of
radio sources. We find that it is important to account for the shot-noise and
clustering of the NVSS sources, as well as kinematic contributions, in
determining the expected dipole signal. We use the clustering redshift method
and a cross-matching technique to refine estimates of the clustering term. We
then derive a probability distribution for the expected NVSS dipole in a
standard CDM cosmological model including all (i.e., kinematic,
shot-noise and clustering) dipole components. Our model agrees with most of the
previous NVSS dipole measurements in the literature at better than . We conclude that the NVSS dipole is consistent with a kinematic
origin for the CMB dipole within CDM.Comment: 24 pages, 9 figures, submitted to Ap
AVATAR: Robust Voice Search Engine Leveraging Autoregressive Document Retrieval and Contrastive Learning
Voice, as input, has progressively become popular on mobiles and seems to
transcend almost entirely text input. Through voice, the voice search (VS)
system can provide a more natural way to meet user's information needs.
However, errors from the automatic speech recognition (ASR) system can be
catastrophic to the VS system. Building on the recent advanced lightweight
autoregressive retrieval model, which has the potential to be deployed on
mobiles, leading to a more secure and personal VS assistant. This paper
presents a novel study of VS leveraging autoregressive retrieval and tackles
the crucial problems facing VS, viz. the performance drop caused by ASR noise,
via data augmentations and contrastive learning, showing how explicit and
implicit modeling the noise patterns can alleviate the problems. A series of
experiments conducted on the Open-Domain Question Answering (ODSQA) confirm our
approach's effectiveness and robustness in relation to some strong baseline
systems
The characterization of the saddle shaped nickel(III) porphyrin radical cation: an explicative NMR model for a ferromagnetically coupled metallo-porphyrin radical
Ni(III)(OETPP˙)(Br)2 is the first Ni(III) porphyrin radical cation with structural and (1)H and (13)C paramagnetic NMR data for porphyrinate systems. Associating EPR and NMR analyses with DFT calculations as a new model is capable of clearly determining the dominant state from two controversial spin distributions in the ring to be the Ni(III) LS coupled with an a1u spin-up radical
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Paxillin facilitates timely neurite initiation on soft-substrate environments by interacting with the endocytic machinery.
Neurite initiation is the first step in neuronal development and occurs spontaneously in soft tissue environments. Although the mechanisms regulating the morphology of migratory cells on rigid substrates in cell culture are widely known, how soft environments modulate neurite initiation remains elusive. Using hydrogel cultures, pharmacologic inhibition, and genetic approaches, we reveal that paxillin-linked endocytosis and adhesion are components of a bistable switch controlling neurite initiation in a substrate modulus-dependent manner. On soft substrates, most paxillin binds to endocytic factors and facilitates vesicle invagination, elevating neuritogenic Rac1 activity and expression of genes encoding the endocytic machinery. By contrast, on rigid substrates, cells develop extensive adhesions, increase RhoA activity and sequester paxillin from the endocytic machinery, thereby delaying neurite initiation. Our results highlight paxillin as a core molecule in substrate modulus-controlled morphogenesis and define a mechanism whereby neuronal cells respond to environments exhibiting varying mechanical properties
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