Bayesian approach to SETI

The search for technosignatures from hypothetical galactic civilizations is going through a new phase of intense activity. For the first time, a significant fraction of the vast search space is expected to be sampled in the foreseeable future, potentially bringing informative data about the abundance of detectable extraterrestrial civilizations, or the lack thereof. Starting from the current state of ignorance about the galactic population of non-natural electromagnetic signals, we formulate a Bayesian statistical model to infer the mean number of radio signals crossing Earth, assuming either non-detection or the detection of signals in future surveys of the Galaxy. Under fairly noninformative priors, we find that not detecting signals within about $1$ kly from Earth, while suggesting the lack of galactic emitters or at best the scarcity thereof, is nonetheless still consistent with a probability exceeding $10$ \% that typically over $\sim 100$ signals could be crossing Earth, with radiated power analogous to that of the Arecibo radar, but coming from farther in the Milky Way. The existence in the Galaxy of potentially detectable Arecibo-like emitters can be reasonably ruled out only if all-sky surveys detect no such signals up to a radius of about $40$ kly, an endeavor requiring detector sensitivities thousands times higher than those of current telescopes. Conversely, finding even one Arecibo-like signal within $\sim 1000$ light years, a possibility within reach of current detectors, implies almost certainly that typically more than $\sim 100$ signals of comparable radiated power cross the Earth, yet to be discovered.Comment: Published in PNAS ahead of print October 1, 2018. Preprint has 13 pages, 7 figures + 7 pages of Supplementary Information with 5 figure

Pauli susceptibility of nonadiabatic Fermi liquids

The nonadiabatic regime of the electron-phonon interaction leads to behaviors of some physical measurable quantities qualitatively different from those expected from the Migdal-Eliashberg theory. Here we identify in the Pauli paramagnetic susceptibility $\chi$ one of such quantities and show that the nonadiabatic corrections reduce $\chi$ with respect to its adiabatic limit. We show also that the nonadiabatic regime induces an isotope dependence of $\chi$, which in principle could be measured.Comment: 7 pages, 3 figures, euromacr.tex, europhys.sty. Replaced with accepted version (Europhysics Letters

Relational Aggression, Positive Urgency and Negative Urgency: Predicting Alcohol Use and Consequences among College Students

Research on relational aggression (indirect and social means of inflicting harm) has previously focused on adolescent populations. The current study extends this research by exploring both the frequency of perpetrating and being the target of relational aggression as it relates to alcohol use outcomes in a college population. Further, this study examines whether positive urgency (e.g., acting impulsively in response to positive emotions) and negative urgency (e.g., acting impulsively in response to negative emotions) moderate the relationship between relational aggression and alcohol outcomes. In this study, 245 college students (65.7% female) completed an online survey. Results indicated greater frequency of perpetrating relational aggression, higher levels of positive urgency, or higher levels of negative urgency was associated with more negative consequences. Further, negative urgency moderated the relationship between frequency of perpetrating aggression and consequences such that aggression was more strongly associated with consequences for those high in urgency. Counter to the adolescent literature, the frequency of being the target of aggression was not associated with more alcohol use. These findings suggest that perpetrators of relational aggression may be at particular risk for negative alcohol-related consequences when they act impulsively in response to negative, but not positive, emotions. These students may benefit from interventions exploring alternative ways to cope with negative emotions

Nonadiabatic Pauli susceptibility in fullerene compounds

Pauli paramagnetic susceptibility $\chi$ is unaffected by the electron-phonon interaction in the Migdal-Eliashberg context. Fullerene compounds however do not fulfill the adiabatic assumption of Migdal's theorem and nonadiabatic effects are expected to be relevant in these materials. In this paper we investigate the Pauli spin susceptibility in nonadiabatic regime by following a conserving approach based on Ward's identity. We find that a sizable renormalization of $\chi$ due to electron-phonon coupling appears when nonadiabatic effects are taken into account. The intrinsic dependence of $\chi$ on the electron-phonon interaction gives rise to a finite and negative isotope effect which could be experimentally detected in fullerides. In addition, we find an enhancement of the spin susceptibility with temperature increasing, in agreement with the temperature dependence of $\chi$ observed in fullerene compounds. The role of electronic correlation is also discussed.Comment: Revtex, 10 pages, 8 figures include

Design for subjective wellbeing: towards a design framework for constructing narrative

We explore the role that interaction with products and services can play in the narratives that we develop about ourselves. We propose a four-level model, which seeks to explain this and use it as the basis for analyzing eight immersion studies. In each, we investigate the role that products and services play in shaping narratives, which in turn reflect our self-identity. We also look at archetypes – the various ideals that we can have about ourselves – and at how the alignment of narratives with these enhances our wellbeing. The model offers the potential to link narrative to design features and to identify new market opportunities. However, we recognize there may be challenges in enabling people to articulate narrative and identify their ideal archetype

Parents\u27 and students\u27 perceptions of college alcohol risk: the role of parental risk perception in intentions to communicate about alcohol

Introduction: The current study aims to examine discrepancies in parents\u27 and college students\u27 perceptions of alcohol risk and the role of perceived risk in predicting parents\u27 intentions to discuss alcohol with their child. Methods: In total, 246 college student–parent dyads (56.1% female students, 77.2% mothers) were recruited from a mid-size university. Participants completed measures of absolute likelihood, comparative likelihood, and severity of alcohol consequences. Results: In comparison to students, parents perceived the risks of alcohol poisoning (p \u3c .001), academic impairment (p \u3c .05), and problems with others (p \u3c .05) to be more likely. In addition, parents rated the majority of alcohol consequences (e.g., passing out, regrettable sexual situation, throwing up) as more severe than students (all ps \u3c .001). However, parents tended to be more optimistic than their child about the comparative likelihood of alcohol consequences. After controlling for demographics and past alcohol communication, greater absolute likelihood (β = .20, p = .016) and less confidence in knowledge of student behavior (β = .20, p = .013) predicted greater intentions to discuss alcohol. Conclusions: Providing parents of college students with information about college drinking norms and the likelihood of alcohol consequences may help prompt alcohol-related communication

Area Coverage of Expanding E.T. Signals in the Galaxy: SETI and Drake's N

The Milky Way Galaxy contains an unknown number, $N$, of civilizations that emit electromagnetic radiation (of unknown wavelengths) over a finite lifetime, $L$. Here we are assuming that the radiation is not produced indefinitely, but within $L$ as a result of some unknown limiting event. When a civilization stops emitting, the radiation continues traveling outward at the speed of light, $c$, but is confined within a shell wall having constant thickness, $cL$. We develop a simple model of the Galaxy that includes both the birthrate and detectable lifetime of civilizations to compute the possibility of a SETI detection at the Earth. Two cases emerge for radiation shells that are (1) thinner than or (2) thicker than the size of the Galaxy, corresponding to detectable lifetimes, $L$, less than or greater than the light-travel time, $\sim 100,000$ years, across the Milky Way, respectively. For case (1), each shell wall has a thickness smaller than the size of the Galaxy and intersects the galactic plane in a donut shape (annulus) that fills only a fraction of the Galaxy's volume, inhibiting SETI detection. But the ensemble of such shell walls may still fill our Galaxy, and indeed may overlap locally, given a sufficiently high birthrate of detectable civilizations. In the second case, each radiation shell is thicker than the size of our Galaxy. Yet, the ensemble of walls may or may not yield a SETI detection depending on the civilization birthrate. We compare the number of different electromagnetic transmissions arriving at Earth to Drake's $N$, the number of currently emitting civilizations, showing that they are equal to each other for both cases (1) and (2). However, for $L < 100,000$ years, the transmissions arriving at Earth may come from distant civilizations long extinct, while civilizations still alive are sending signals yet to arrive.Comment: 10 pages, 2 figures, to be published in PAS

Multicenter Validation of the Vasoactive-Ventilation-Renal Score as a Predictor of Prolonged Mechanical Ventilation After Neonatal Cardiac Surgery

Objectives: We sought to validate the Vasoactive-Ventilation-Renal score, a novel disease severity index, as a predictor of outcome in a multicenter cohort of neonates who underwent cardiac surgery. Design: Retrospective chart review. Setting: Seven tertiary-care referral centers. Patients: Neonates defined as age less than or equal to 30 days at the time of cardiac surgery. Interventions: Ventilation index, Vasoactive-Inotrope Score, serum lactate, and Vasoactive-Ventilation-Renal score were recorded for three postoperative time points: ICU admission, 6 hours, and 12 hours. Peak values, defined as the highest of the three measurements, were also noted. Vasoactive-Ventilation-Renal was calculated as follows: ventilation index + Vasoactive-Inotrope Score + Δ creatinine (change in creatinine from baseline × 10). Primary outcome was prolonged duration of mechanical ventilation, defined as greater than 96 hours. Receiver operative characteristic curves were generated, and abilities of variables to correctly classify prolonged duration of mechanical ventilation were compared using area under the curve values. Multivariable logistic regression modeling was also performed. Measurements and Main Results: We reviewed 275 neonates. Median age at surgery was 7 days (25th–75th percentile, 5–12 d), 86 (31%) had single ventricle anatomy, and 183 (67%) were classified as Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Category 4 or 5. Prolonged duration of mechanical ventilation occurred in 89 patients (32%). At each postoperative time point, the area under the curve for prolonged duration of mechanical ventilation was significantly greater for the Vasoactive-Ventilation-Renal score as compared to the ventilation index, Vasoactive-Inotrope Score, and serum lactate, with an area under the curve for peak Vasoactive-Ventilation-Renal score of 0.82 (95% CI, 0.77–0.88). On multivariable analysis, peak Vasoactive-Ventilation-Renal score was independently associated with prolonged duration of mechanical ventilation, odds ratio (per 1 unit increase): 1.08 (95% CI, 1.04–1.12). Conclusions: In this multicenter cohort of neonates who underwent cardiac surgery, the Vasoactive-Ventilation-Renal score was a reliable predictor of postoperative outcome and outperformed more traditional measures of disease complexity and severity

Breakdown of Migdal's theorem and intensity of electron-phonon coupling in high-Tc superconductors

In this article we quantify the possible effects of the breakdown of Migdal's theorem on the electron-phonon (e-p) coupling constant, on the critical temperature and on the superconducting gap by examining different kinds of superconducting materials either with low and high critical temperature. We use the theoretical approach developed by Grimaldi, Pietronero and Strassler [PRB 52, 10516 & 10530 (1995)] on experimental data taken both from literature and from our recent break-junction tunneling experiments in Bi_2Sr_2CaCu_2O_{8+x} (BSCCO) [Physica C 275, 162 (1997) and cond-mat/9612220]. The results show that a large violation of the Migdal's theorem (as in BSCCO) yields to a large increase of the observed e-p coupling constant and, in a first approximation and by direct solution of the Eliashberg equations, to large but different increases of Tc and gap. The same theory gives no modifications when applied to low-Tc conventional superconductors. In BSCCO, the renormalized values of the e-p coupling constant and of the ratio 2Delta/kTc (1.85 and 4.98, respectively) are compatible with a strong-coupling electron-phonon origin of superconductivity.Comment: 11 pages REVTeX file, 3 PostScript figures, to be published in Phys. Rev. B (Rapid Commun.

Sleep Quality and Alcohol Risk in College Students: Examining the Moderating Effects of Drinking Motives

Objective Sleep problems and alcohol misuse are common issues experienced by college students that can have detrimental effects on overall health. Previous work indicates a strong relationship between poor sleep quality and alcohol risk in this population. This study explored the moderating effect of drinking motives in the relationship between global sleep quality and experience of alcohol-related negative consequences. Participants College students (N = 1,878) who reported past-month drinking. Methods Participants completed online surveys assessing sleep and alcohol-related behaviors. Results Poorer sleep quality and higher drinking motives (coping, conformity, and enhancement) predicted greater alcohol-related consequences, controlling for drinking. Further, coping motives moderated the relationship between sleep quality and consequences such that participants reporting poor sleep and high coping motives experienced heightened levels of consequences. Conclusions These findings advance the understanding of the relationship between sleep problems and alcohol-related risk and provide implications for targeted campus-based health promotion interventions