Linear study of the precessional fishbone instability

The precessional fishbone instability is an m = n = 1 internal kink mode destabilized by a population of trapped energetic particles. The linear phase of this instability is studied here, analytically and numerically, with a simplified model. This model uses the reduced magneto-hydrodynamics (MHD) equations for the bulk plasma and the Vlasov equation for a population of energetic particles with a radially decreasing density. A threshold condition for the instability is found, as well as a linear growth rate and frequency. It is shown that the mode frequency is given by the precession frequency of the deeply trapped energetic particles at the position of strongest radial gradient. The growth rate is shown to scale with the energetic particle density and particles energy while it is decreased by continuum damping

A photometric search for transients in galaxy clusters

We have begun a program to search for supernovae and other transients in the fields of galaxy clusters with the 2.3m Bok Telescope on Kitt Peak. We present our automated photometric methods for data reduction, efficiency characterization, and initial spectroscopy. With this program, we aim to ultimately identify $\sim$25-35 cluster SN Ia ($\sim$10 of which will be intracluster, hostless events) and constrain the SN Ia rate associated with old, passive stellar populations. With these measurements we will constrain the relative contribution of hostless and hosted SN Ia to the metal enrichment of the intracluster medium. In the current work, we have identified a central excess of transient events within $1.25 r_{200}$ in our cluster fields after statistically subtracting out the 'background' transient rate taken from an off-cluster CCD chip. Based on the published rate of SN Ia for cluster populations we estimate that $\sim$20 percent of the excess cluster transients are due to cluster SN Ia, a comparable fraction to core collapse (CC) supernovae and the remaining are likely to be active galactic nuclei. Interestingly, we have identified three intracluster SN candidates, all of which lay beyond $R>r_{200}$. These events, if truly associated with the cluster, indicate a large deficit of intracluster (IC) SN at smaller radii, and may be associated with the IC stars of infalling groups or indicate that the intracluster light (ICL) in the cluster outskirts is actively forming stars which contribute CC SN or prompt SN Ia.Comment: Updated to match accepted version; 26 pages, 14 figures, AJ accepte

Metallicities and dust content of proximate damped Lyman alpha systems in the Sloan Digital Sky Survey

Composite spectra of 85 proximate absorbers (log N(HI)>20 and velocity difference between the absorption and emission redshift, dv<10,000 km/s) in the SDSS are used to investigate the trends of metal line strengths with velocity separation from the QSO. We construct composites in 3 velocity bins: dv<3000 km/s, 30006000 km/s, with further sub-samples to investigate the metal line dependence on N(HI) and QSO luminosity. Low (e.g. SiII and FeII) and high ionization (e.g. SiIV and CIV) species alike have equivalent widths (EWs) that are larger by factors of 1.5 -- 3 in the dv<3000 km/s composite, compared to the dv>6000 km/s spectrum. The EWs show an even stronger dependence on dv if only the highest neutral hydrogen column density (log N(HI)>20.7) absorbers are considered. We conclude that PDLAs generally have higher metallicities than intervening absorbers, with the enhancement being a function of both dv and N(HI). It is also found that absorbers near QSOs with lower rest-frame UV luminosities have significantly stronger metal lines. We speculate that absorbers near to high luminosity QSOs may have had their star formation prematurely quenched. Finally, we search for the signature of dust reddening by the PDLAs, based on an analysis of the QSO continuum slopes relative to a control sample and determine a limit of E(B-V)<0.014 for an SMC extinction curve. This work provides an empirical motivation for distinguishing between proximate and intervening DLAs, and establishes a connection between the QSO environment and galaxy properties at high redshifts.Comment: Accepted for publication in MNRA

The nature of proximate damped Lyman alpha systems

We present high resolution echelle spectra of 7 proximate damped Lyman alpha (PDLA) systems whose relative velocity separation from the background quasar is Delta V < 3000 km/s. Combining our sample with a further 9 PDLAs from the literature we compare the chemical properties of the proximate systems with a control sample of intervening DLAs. Taken at face value, the sample of 16 PDLAs exhibits a wide range of metallicities, ranging from Z ~ 1/3 Z_sun down to Z ~ 1/1000 Z_sun, including the DLA with the lowest N(SiII)/N(HI) yet reported in the literature. We find several pieces of evidence that indicate enhanced ionization and the presence of a hard ionizing spectrum in PDLAs which lead to properties that contrast with the intervening DLAs, particularly when the N(HI) is low. The abundances of Zn, Si and S in PDLAs with log N(HI) > 21, where ionization corrections are minimized, are systematically higher than the intervening population by a factor of around 3. We also find possible evidence for a higher fraction of NV absorbers amongst the PDLAs, although the statistics are still modest. 6/7 of our echelle sample show high ionization species (SiIV, CIV, OVI or NV) offset by >100 km/s from the main low ion absorption. We analyse fine-structure transitions of CII* and SiII* to constrain the PDLA distance from the QSO. Lower limits range from tens of kpc up to >160 kpc for the most stringent limit. We conclude that (at least some) PDLAs do exhibit different characteristics relative to the intervening population out to 3000 km/s (and possibly beyond). Nonetheless, the PDLAs appear distinct from lower column density associated systems and the inferred QSO-absorber separations mean they are unlikely to be associated with the QSO host. We speculate that the PDLAs preferentially sample more massive galaxies in more highly clustered regions of the high redshift universe.Comment: Accepted for publication in MNRAS. Abstract abridged

A High-Velocity Narrow Absorption Line Outflow in the Quasar J212329.46-005052.9

We report on a variable high-velocity narrow absorption line outflow in the redshift 2.3 quasar J2123-0050. Five distinct outflow systems are detected with velocity shifts from -9710 to -14,050 km/s and CIV 1548,1551 line widths of FWHM = 62-164 km/s. These data require five distinct outflow structures with similar kinematics, physical conditions and characteristic sizes of order 0.01-0.02 pc. The most likely location is ~5 pc from the quasar. The coordinated line variations in <0.63 yr (rest) are best explained by global changes in the outflow ionization caused by changes in the quasar's ionizing flux. The absence of strong X-ray absorption shows that radiative shielding is not needed to maintain the moderate ionizations and therefore, apparently, it is not needed to facilitate the radiative acceleration to high speeds. The kinetic energy yield of this flow is at least two orders of magnitude too low to be important for feedback to the host galaxy's evolution.Comment: 20 pages. In press with MNRA

How do self-assessment of alexithymia and sensitivity to bodily sensations relate to alcohol consumption?

Background Alexithymia describes an abnormality of emotional experience that is commonly expressed among individuals with addiction and alcohol abuse disorders. Alexithymic individuals are characterized by difficulties in identifying and describing their emotions. This impairment is linked to the development and maintenance of addiction. Moreover, an emergent theory suggests alexithymia is itself secondary to a failure of interoception (sensitivity to internal bodily signals, including physiological arousal states). Methods The present study tested for hypothesized contributory roles of alexithymia and dysfunctional interoception in the expression of binge drinking. Alexithymia, subjective sensitivity to bodily sensations, and alcohol consumption scores were quantified using the Toronto Alexithymia Scale, the Body Perception Questionnaire and the Alcohol Use Questionnaire respectively, in a normative sample (N=600). Regression and bootstrapping mediation analyses were used to test the hypothesis that alexithymia mediated the association between sensitivity to bodily sensations and alcohol consumption. Results Alexithymia was positively correlated with sensitivity to bodily sensations and with alcohol consumption. Mediation analysis revealed that alexithymia, and more precisely, difficulty in identifying feelings, mediated the relationship between sensitivity to bodily sensations and alcohol consumption, such that the predictive effect of sensitivity to bodily sensations on alcohol intake became non-significant when controlling for alexithymia. Conclusions These results indicate that alexithymia is associated with subjective hypersensitivity to bodily sensations. Moreover, our findings support the theoretical proposal that alexithymia is an expression of impaired processing of bodily sensations including physiological arousal, which underpin the development of maladaptive coping strategies, including alcohol use disorders. Our observations extend a growing literature emphasizing the importance of interoception and alexithymia in addiction, which can inform the development of new therapeutic strategies

Ernst Freund as Precursor of the Rational Study of Corporate Law

Gindis, David, Ernst Freund as Precursor of the Rational Study of Corporate Law (October 27, 2017). Journal of Institutional Economics, Forthcoming. Available at SSRN: https://ssrn.com/abstract=2905547, doi: https://dx.doi.org/10.2139/ssrn.2905547The rise of large business corporations in the late 19th century compelled many American observers to admit that the nature of the corporation had yet to be understood. Published in this context, Ernst Freund's little-known The Legal Nature of Corporations (1897) was an original attempt to come to terms with a new legal and economic reality. But it can also be described, to paraphrase Oliver Wendell Holmes, as the earliest example of the rational study of corporate law. The paper shows that Freund had the intuitions of an institutional economist, and engaged in what today would be called comparative institutional analysis. Remarkably, his argument that the corporate form secures property against insider defection and against outsiders anticipated recent work on entity shielding and capital lock-in, and can be read as an early contribution to what today would be called the theory of the firm.Peer reviewe

Signaling of angiotensin II-induced vascular protein synthesis in conduit and resistance arteries in vivo

BACKGROUND: From in vitro studies, it has become clear that several signaling cascades are involved in angiotensin II-induced cellular hypertrophy. The aim of the present study was to determine some of the signaling pathways mediating angiotensin II (Ang II)-induced protein synthesis in vivo in large and small arteries. METHODS: Newly synthesized proteins were labeled during 4 hours with tritiated leucine in conscious control animals, or animals infused for 24 hours with angiotensin II (400 ng/kg/min). Hemodynamic parameters were measure simultaneously. Pharmacological agents affecting signaling cascades were injected 5 hours before the end of Ang II infusion. RESULTS: Angiotensin II nearly doubled the protein synthesis rate in the aorta and small mesenteric arteries, without affecting arterial pressure. The AT(1 )receptor antagonist Irbesartan antagonized the actions of Ang II. The Ang II-induced protein synthesis was associated with increased extracellular signal-regulated kinases (ERK)1/2 phosphorylation in aortic, but not in mesenteric vessels. Systemic administration of PD98059, an inhibitor of the ERK-1/2 pathway, produced a significant reduction of protein synthesis rate in the aorta, and only a modest decrease in mesenteric arteries. Rapamycin, which influences protein synthesis by alternative signaling, had a significant effect in both vessel types. Rapamycin and PD98059 did not alter basal protein synthesis and had minimal effects on arterial pressure. CONCLUSION: ERK1/2 and rapamycin-sensitive pathways are involved in pressure-independent angiotensin II-induced vascular protein synthesis in vivo. However, their relative contribution may vary depending on the nature of the artery under investigation

The nature of damped Lyman alpha and sub-damped Lyman alpha absorbers

We present arguments based on the measured abundances in individual damped Lyman alpha systems (DLAs) and sub-damped Lyman alpha systems (sub-DLAs), and also the average abundances inferred in large samples of QSO absorption line systems, to suggest that the amount of dust in intervening QSO absorbers is small and is not responsible for missing many QSOs in magnitude limited QSO surveys. While we can not totally rule out a bimodal dust distribution with a population of very dusty, metal rich, absorbers which push the background QSOs below the observational threshold of current optical spectroscopic studies, based upon the current samples it appears that the metallicity in QSO absorbers decreases with increase in H I column densities beyond 10^{19} cm^{-2}. Thus the sub-DLA population is more metal rich than the DLAs, a trend which may possibly extend to the non-damped Lyman limit systems (NDLLS). Based on the recently discovered mass-metallicity relation for galaxies, we suggest that most sub-DLAs and possibly NDLLS, are associated with massive spiral/elliptical galaxies while most DLAs are associated with low mass galaxies. The sub-DLA galaxies will then contribute a larger fraction of total mass (stellar and ISM) and therefore metals, to the cosmic budget, specially at low redshifts, as compared to the DLAs.Comment: Expanded version. accepted for publication in A&A, 7 pages, 2 figure

Male/Female Is Not Enough: Adding Measures of Masculinity and Femininity to General Population Surveys

Survey research and sociological theory each provide insights into how and why people and groups act, think, and feel. Sociological theories identify what concepts are important for understanding and representing the social world. That is, sociological theories inform what to measure in surveys, and, to a certain extent, how to measure it. Survey research permits sociologists to carefully specify what is to be measured vis a vis sociological theory, setting surveys apart as a social research tool. It is this level of specification of concepts and measures that allow surveys to provide continued value at a time when “big data” proliferate. High quality survey measurement and estimation is necessary for sociologists to evaluate sociological theory among generalizable samples with well-developed questions, leading to further refinement and improvement of the theory and improved understanding of the social world. High quality surveys also provide insights into where sociological theories fail and where they must be adjusted for different subgroups, as well as basic insights into the prevalence of outcomes of interest. Together, sociological theory and survey methods produce insights about society that can inform decision-making and social policy. This mutually reinforcing relationship between sociological theory and survey methods requires sociological theory to evolve from insights obtained using survey methods and survey measurement to evolve with advances in in sociological theory. The measurement of sex and gender in surveys is one area where the development of survey measures has not kept pace with sociological theory and empirical, largely qualitative, findings. Contemporary gender theory sees sex and gender as separate concepts, both of which are important for understanding behaviors and outcomes. Yet, virtually all contemporary surveys measure sex as a binary “male” versus “female” categorization and fail to measure gender, ignoring important heterogeneity in gender identification that may exist within sex categories and any overlap that may occur across categories. Both gender scholars and survey researchers are potentially affected by this shortcoming of modern survey measurement. Gender scholars lose an important tool for assessing gender theories, especially on generalizable samples, risking conclusions that are specific to a small group of individuals rather than the population at large. Survey researchers risk producing theoretically obsolete data, limiting the utility of the data or potentially generating misleading conclusions. Survey data that fail to capture and reflect modern and complex understandings of our social realities also face increased risk of being replaced by “big data” such as administrative and social media data. Survey data that do reflect modern and complex understandings can bring value not available in administrative or other data and are therefore unlikely to be replaced. This paper is part of a growing chorus advocating for updates to how modern surveys measure sex and gender. We argue that the reliance on a single binary measure of sex (male or female) is out of step with current sociological understandings of sex and gender. In response, we propose and test a new theoretically-informed gradational measure of gender identification in a nationally representative mail survey. We evaluate whether respondents answer the gender measure and examine the reliability and predictive validity of the measure. In particular, we examine whether measuring gender gradationally adds explanatory value beyond sex on important social outcomes such as sexuality, childcare, grocery shopping, housework, working for pay, and military service. We also examine whether sex moderates the effect of gender identification in the ways that sociological theory would suggest on these outcomes