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Embedding imperatives
No full textThis paper extends the centered world analysis of embedded epistemic modals proposed in Stephenson (2007) to account for embedded imperatives. A dissimilarity between epistemic and imperative modals in variability of modal force is accounted for by relying on Rullmann et al.’s (2008) analysis of Salish modals
Embedding imperatives in English
No full textAlthough it has generally been claimed otherwise (cf. Katz and Postal 1964, Sadock and Zwicky 1985, Palmer 1986, Rivero and Terzi 1995, Platzack and Rosengren 1998, Han 1998 among others), it holds that embedded imperatives exist in English. We describe their main characteristics and provide an account of these by relying on Schwager\u27s (2006) propositional analysis of imperatives, where imperatives are treated as modalized sentences. The imperative modal is thereby relativized to eventualities (cf. Hacquard 2006)
Measurement of the depth of maximum of air-shower profiles with energies between ▫▫ eV using the surface detector of the Pierre Auger Observatory and deep learning
Get PDFWe report an investigation of the mass composition of cosmic rays with energies
from 3 to 100 EeV (1 EeV = 10[sup]18 eV) using the distributions of the depth of shower
maximum Xmax. The analysis relies on ∼50,000 events recorded by the surface detector
of the Pierre Auger Observatory and a deep-learning-based reconstruction algorithm.
Above energies of 5 EeV, the dataset offers a 10-fold increase in statistics with respect to
fluorescence measurements at the Observatory. After cross-calibration using
the fluorescence detector, this enables the first measurement of the evolution of the mean
and the standard deviation of the Xmax distributions up to 100 EeV.
Our findings are threefold: (i) The evolution of the mean logarithmic mass toward a heavier
composition with increasing energy can be confirmed and is extended to 100 EeV.
(ii) The evolution of the fluctuations of Xmax toward a heavier and purer composition
with increasing energy can be confirmed with high statistics. We report a rather heavy
composition and small fluctuations in Xmax at the highest energies.
(iii) We find indications for a characteristic structure beyond a constant change
in the mean logarithmic mass, featuring three breaks that are observed in proximity
to the ankle, instep, and suppression features in the energy spectrum
A systematically selected sample of luminous, long-duration, ambiguous nuclear transients
Get PDFWe present a search for luminous long-duration ambiguous nuclear transients (ANTs) similar to the unprecedented discovery of the extreme ambiguous event AT2021lwx with a d rise time and luminosity erg s. We use the Lasair transient broker to search Zwicky Transient Facility (ZTF) data for transients lasting more than one year and exhibiting smooth declines. Our search returns 59 events, 7 of which we classify as ANTs assumed to be driven by accretion onto supermassive black holes. We propose the remaining 52 are stochastic variability from regular supermassive black hole accretion rather than distinct transients. We supplement the seven ANTs with three nuclear transients in ZTF that fail the light curve selection but have clear single flares and spectra that do not resemble typical active galactic nucleus. All of these 11 ANTs have a mid-infrared flare from an assumed dust echo, implying the ubiquity of dust around the black holes giving rise to ANTs. No events are more luminous than AT2021lwx, but one (ZTF19aamrjar) has twice the duration and a higher integrated energy release. On the other extreme, ZTF20abodaps reaches a luminosity close to AT2021lwx with a rise time d and that fades smoothly in d. We define a portion of rise-time versus flare amplitude space that selects ANTs with per cent purity against variable AGNs. We calculate a volumetric rate of Mpc yr, consistent with the events being caused by tidal disruptions of intermediate and high-mass stars
