ABSTRACT
Rapidly evolving transients (RETs), also termed fast blue optical transients, are a recently discovered group of astrophysical events that display rapid luminosity evolution. RETs typically ...rise to peak in less than 10 d and fade within 30, a time-scale unlikely to be compatible with the decay of Nickel-56 that drives conventional supernovae (SNe). Their peak luminosity spans a range of −15 < Mg < −22.5, with some events observed at redshifts greater than 1. Their evolution on fast time-scales has hindered high-quality follow-up observations, and thus their origin and explosion/emission mechanism remains unexplained. In this paper, we present the largest sample of RETs to date, comprising 106 objects discovered by the Dark Energy Survey, and perform the most comprehensive analysis of RET host galaxies. Using deep-stacked photometry and emission lines from OzDES spectroscopy, we derive stellar masses and star formation rates (SFRs) for 49 host galaxies, and metallicities (O/H) for 37. We find that RETs explode exclusively in star-forming galaxies and are thus likely associated with massive stars. Comparing RET hosts to samples of host galaxies of other explosive transients as well as field galaxies, we find that RETs prefer galaxies with high specific SFRs (〈log (sSFR)〉 ∼ −9.6), indicating a link to young stellar populations, similar to stripped-envelope SNe. RET hosts appear to show a lack of chemical enrichment, their metallicities akin to long-duration gamma-ray bursts and superluminous SN host galaxies (〈12 + log (O/H)〉 ∼ 9.4). There are no clear relationships between mass or SFR of the host galaxies and the peak magnitudes or decline rates of the transients themselves.
Cigarettes acquire reinforcing properties from nicotine and from cues associated with their intake. However, smoking in males and females may be reinforced differentially. Smoking in females is ...posited to be influenced more by cues whereas male smoking is influenced predominantly by the direct pharmacological actions of nicotine in the brain. Menstrual cycle phase may contribute to some of the sex differences observed in smokers. We hypothesized that females may report more intense craving to smoking cue exposure than males and, further, that female craving scores may be influenced by menstrual cycle phase. Thus, we reexamined previously collected cue exposure data with respect to sex and cycle phase. Self-report measures were collected from subjects prior to and immediately following exposure to visual smoking stimuli. The study included 69 male and 41 female treatment-seeking subjects who smoked more than 15 cigarettes per day for more than 10 years. Females were grouped according to cycle phase. Of the female subjects, 17 were classified as follicular phase females (FFemales) and 24 were classified as luteal phase females (LFemales). Change scores were calculated from the subjective data collected before and after stimulus presentation. Contrary to our hypothesis, overall, males and all females did not differ in their level of cue-induced craving; however, when females were separated into groups by cycle phase, FFemales reported significantly less craving than either males or LFemales (p<.05). The suppressed craving response in FFemales suggests an influence of cycle phase on cue-induced craving.
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