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In recent years, the discovery of massive quasars at
has provided a striking challenge to our understanding of the origin and growth of supermassive black holes in the early Universe. Mounting observational and theoretical evidence indicates the viability of massive seeds, formed by the collapse of supermassive stars, as a progenitor model for such early, massive accreting black holes. Although considerable progress has been made in our theoretical understanding, many questions remain regarding how (and how often) such objects may form, how they live and die, and how next generation observatories may yield new insight into the origin of these primordial titans. This review focusses on our present understanding of this remarkable formation scenario, based on the discussions held at the Monash Prato Centre from November 20 to 24, 2017, during the workshop ‘Titans of the Early Universe: The Origin of the First Supermassive Black Holes’.
We study the relationship between societal trust and risk-taking in the banking industry. Prior literature has found that societal trust is positively related to both financial reporting conservatism and financial reporting transparency, which reduce bank managers’ ability to take excessive risk. Additionally, bank managers in high-trust countries are more likely to exhibit higher pro-social behavior and, therefore, less likely to take excessive risk for personal benefit. Consistent with these arguments, we document that banks in countries with higher societal trust exhibit lower risk-taking and that these banks also experienced less financial trouble and fewer failures during the 2007–2009 financial crisis.
There is growing interest in monitoring soil biological health to complement the traditional evaluation of soil physical and chemical characteristics in agricultural fields. Activity of soil microorganisms mediates many essential soil processes that affect fertility, and, therefore, essential to the successful adoption of precision agriculture. However, there are technical limitations to cost-effective monitoring of spatial and temporal dynamics of soil biological activity across agricultural landscapes. This paper summarizes three consecutive studies on in situ measurement of soil biological activity. The first study reveals spatial heterogeneity of microbial population growth in three agricultural fields using bio-films. In the second study, microbiological activity was analyzed using a substrate-induced respiration technique. This technique was evaluated through a series of soil toxicity experiments that involved a comparison of fresh and autoclaved soil samples. Finally, the aim of the third study was to develop a portable instrumented system to evaluate carbon dioxide concentrations in soil by extracting air stored within the soil pores. This instrument was tested under various conditions to quantify the effects of soil moisture, compaction and presence of glucose (artificially increased microbial respiration). Optimization of the discussed techniques will allow for detailed mapping of these indices of soil biological health and their interactions with the physical and chemical environment at any specific point in time.
Introduction: The Collaborative Emergency Centre (CEC) model of health care delivery was implemented in rural Nova Scotia in July 2011 without an identifiable, directly comparable precedent. It features interprofessional teams working under one roof with the goal of providing improved access to timely primary health care, and appropriate access to 24/7 emergency care. One important component of the CEC model is overnight staffing by a paramedic/registered nurse team consulting with an offsite physician via telephone. Our objective was to ascertain the attitudes, feelings and experiences of paramedics working within the CEC construct. Methods: We conducted a qualitative study, guided by the principles of grounded theory. Semi-structured telephone interviews were carried out by the principal investigator with paramedics with experience working in a CEC in the province of Nova Scotia. Interviews were recorded, transcribed and analyzed. Analysis involved an inductive and deductive grounded approach using constant comparative analysis. Data collection and analysis continued until thematic saturation was reached. Results: Fourteen paramedics participated in the study. The majority were male (n=10, 71%), with a mean age of 44 years (STD=8.8) and mean experience as a paramedic of 14 years (STD=9.7). Four major themes were identified from the data: 1) leadership support, encompassing support from Emergency Health Services and Government prior to and after implementation of the model, 2) team work and collaboration, including interprofessional relationships among members of the healthcare team, 3) value to patients and the communities, and 4) professional and personal benefits of working in CECs. Conclusion: Paramedics have found working in CECs to be both professionally and personally rewarding. They perceive the CEC model to be of great value to the patients and communities it serves. Key lessons that might help future expansion of the model in Nova Scotia and other jurisdictions across the country include the importance of building and strengthening relationships between paramedics and nurses, and the need for greater feedback and support from leadership.
Supernovae are important probes of the properties of stars at high redshifts because they can be detected at early epochs and their masses can be inferred from their light curves. Direct detection of the first cosmic explosions in the universe will only be possible with JWST, WFIRST and the next generation of extremely large telescopes. But strong gravitational lensing by massive clusters, like those in the Frontier Fields, could reveal supernovae at slightly lower redshifts now by magnifying their flux by factors of 10 or more. We find that Frontier Fields will likely discover dozens of core-collapse supernovae at 5 < z < 12. Future surveys of cluster lenses similar in scope to Frontier Fields by JWST might find hundreds of these events out to z ~ 15 - 17. Besides revealing the masses of early stars, these ancient supernovae could also constrain cosmic star formation rates in the era of first galaxy formation.
Negative emotionality is a distinguishing feature of borderline personality disorder (BPD). However, this person-level characteristic has not been examined as a marker of vulnerability in the development of this disorder. The current study utilized a multimethod approach to examine the interplay between negative emotional reactivity and cumulative exposure to family adversity on the development of BPD symptoms across 3 years (ages 16–18) in a diverse, at-risk sample of adolescent girls (N = 113). A latent variable of negative emotional reactivity was created from multiple assessments at age 16: self-report, emotion ratings to stressors from ecological assessments across 1 week, and observer-rated negative affectivity during a mother–daughter conflict discussion task. Exposure to family adversity was measured cumulatively between ages 5 and 16 from annual assessments of family poverty, single parent household, and difficult life circumstances. The results from latent growth curve models demonstrated a significant interaction between negative emotional reactivity and family adversity, such that exposure to adversity strengthened the association between negative emotional reactivity and BPD symptoms. In addition, family adversity predicted increasing BPD symptoms during late adolescence. These findings highlight negative emotional reactivity as a marker of vulnerability that ultimately increases risk for the development of BPD symptoms.
Theories of borderline personality disorder (BPD) postulate that high-risk transactions between caregiver and child are important for the development and maintenance of the disorder. Little empirical evidence exists regarding the reciprocal effects of parenting on the development of BPD symptoms in adolescence. The impact of child and caregiver characteristics on this reciprocal relationship is also unknown. Thus, the current study examines bidirectional effects of parenting, specifically harsh punishment practices and caregiver low warmth, and BPD symptoms in girls aged 14–17 years based on annual, longitudinal data from the Pittsburgh Girls Study (N = 2,451) in the context of child and caregiver characteristics. We examined these associations through the use of autoregressive latent trajectory models to differentiate time-specific variations in BPD symptoms and parenting from the stable processes that steadily influence repeated measures within an individual. The developmental trajectories of BPD symptoms and parenting were moderately associated, suggesting a reciprocal relationship. There was some support for time-specific elevations in BPD symptoms predicting subsequent increases in harsh punishment and caregiver low warmth. There was little support for increases in harsh punishment and caregiver low warmth predicting subsequent elevations in BPD symptoms. Child impulsivity and negative affectivity, and caregiver psychopathology were related to parenting trajectories, while only child characteristics predicted BPD trajectories. The results highlight the stability of the reciprocal associations between parenting and BPD trajectories in adolescent girls and add to our understanding of the longitudinal course of BPD in youth.
Neuromodulation devices such as deep brain stimulators (DBS), spinal cord
stimulators (SCS) and cochlear implants (CIs) use electrodes in contact with
tissue to deliver electrical pulses to targeted cells. In general, the
neuromodulation industry has been evolving towards smaller, less invasive
devices. Improving power efficiency of these devices can reduce battery storage
requirements. Neuromodulation devices can realize significant power savings if
the impedance to charge transfer at the electrode-tissue interface can be
reduced. High electrochemical impedance at the surface of stimulation
microelectrodes results in larger polarization voltages. Decreasing this
polarization voltage response can reduce power required to deliver the current
pulse. One approach to doing this is to reduce the electrochemical impedance at
the electrode surface. Previously we have reported on a novel electrochemically
deposited 60:40% platinum-iridium (Pt-Ir) electrode material that lowered the
electrode impedance by two orders of magnitude or more.
This study compares power consumption of an electrochemically deposited Pt-Ir
stimulating microelectrode to that of standard Pt-Ir probe microelectrode
produced using conventional techniques. Both electrodes were tested using
in-vitro in phosphate buffered saline (PBS) solution and
in-vivo (live rat) models.
Massive Population III stars die as pair-instability supernovae (PI SNe), the most energetic thermonuclear explosions in the universe with energies up to 100 times those of Type Ia or Type II SNe. Their extreme luminosities may allow them to be observed from the earliest epochs, revealing the nature of Pop III stars and the primitive galaxies in which they reside. We present numerical simulations of Pop III PI SNe done with the radiation hydrodynamics code RAGE and calculations of their light curves and spectra performed with the SPECTRUM code. We find that 150 - 250 M⊙ PI SNe will be visible to the James Webb Space Telescope (JWST) out to z ~ 30 and to z ~ 15 - 20 in all-sky NIR surveys by the Wide Field Infrared Survey Telescope (WFIRST).
A critical feature – and resource – of many face-to-face service encounters is a ubiquitous bureaucratic document, the ‘standard form’ (see especially Suchman and Whalen 1994). But despite Max Weber's classic observations of the crucial role played by written documents (‘the files’) and the work of those who generate and administer them (‘subaltern officials and scribes of all sorts’) in all matters of organisational business (Weber 1978: vol. II, 957), study of the functions and uses of documents in modern organisations, whether paper or electronic, has been largely neglected by the human sciences. Strangely, this has even been the case for studies of formal organisations and bureaucracies, which rarely make more than a passing reference to any actual documenting, reading or filing activities. And this is despite the fact that from the invention of the first writing systems in the late fourth millennium BCE, and especially from the printing revolution that began in early modern Europe (Eisenstein 1983) and continues to this day, written documents were absolutely crucial to the co-ordination of many people across time and space by rendering information concrete and readily distributable (see especially Giddens 1979, 1987).
In this chapter, we undertake a detailed empirical examination of how documents enter into the concerting and co-ordinating of organisational activity and, in doing so, how this opens up and ties locally achieved co-ordinative practices into courses of action beyond a particular interaction.
The first stars are key to the formation of primeval galaxies, early cosmological reionization, and the assembly of supermassive black holes. Although Population III stars lie beyond the reach of direct observation, their chemical imprint on long-lived second generation stars may yield indirect measures of their masses. While numerical models of primordial SN nucleosynthetic yields have steadily improved in recent years, they have not accounted for the chemical abundances of ancient metal-poor stars in the Galactic halo. We present new two-dimensional models of 15 - 40 M⊙ primordial SNe that capture the effect of progenitor rotation, mass, metallicity, and explosion energy on elemental yields. Rotation dramatically alter the structure of zero-metallicity stars, expanding them to much larger radii. This promotes mixing between elemental shells by the SN shock and fallback onto the central remnant, both of which govern which elements escape the star. We find that a Salpeter IMF average of our yields for Z=0 models with explosion energies of 2.4 × 1051 ergs or less is in good agreement with the abundances measured in extremely metal-poor stars. Because these stars were likely enriched by early SNe from a well-defined IMF, our models indicate that the bulk of the metals in the early universe were synthesized by low-mass primordial stars.
This study investigated pupillary and behavioral responses to an emotional word valence identification paradigm among 32 pre-/early pubertal and 34 mid-/late pubertal typically developing children and adolescents. Participants were asked to identify the valence of positive, negative, and neutral words while pupil dilation was assessed using an eyetracker. Mid-/late pubertal children showed greater peak pupillary reactivity to words presented during the emotional word identification task than pre-/early pubertal children, regardless of word valence. Mid-/late pubertal children also showed smaller sustained pupil dilation than pre-/early pubertal children after the word was no longer on screen. These findings were replicated controlling for participants' age. In addition, mid-/late pubertal children had faster reaction times to all words, and rated themselves as more emotional during their laboratory visit compared to pre-/early pubertal children. Greater recall of emotional words following the task was associated with mid-/late pubertal status, and greater recall of emotional words was also associated with higher peak pupil dilation. These results provide physiological, behavioral, and subjective evidence consistent with a model of puberty-specific changes in neurobehavioral systems underpinning emotional reactivity.
This article offers a multilevel perspective on resilience to depression, with a focus on interactions among social and neurobehavioral systems involved in emotional reactivity and regulation. We discuss models of cross-contextual mediation and moderation by which the social context influences or modifies the effects of resilience processes at the biological level, or the biological context influences or modifies the effects of resilience processes at the social level. We highlight the socialization of emotion regulation as a candidate process contributing to resilience against depression at the social context level. We discuss several factors and their interactions across levels—including genetic factors, stress reactivity, positive affect, neural systems of reward, and sleep—as candidate processes contributing to resilience against depression at the neurobehavioral level. We then present some preliminary supportive findings from two studies of children and adolescents at high risk for depression. Study 1 shows that elevated neighborhood level adversity has the potential to constrain or limit the benefits of protective factors at other levels. Study 2 indicates that ease and quickness in falling asleep and a greater amount of time in deep Stage 4 sleep may be protective against the development of depressive disorders for children. The paper concludes with a discussion of clinical implications of this approach.
This 2002 monograph offers a broad investigative tool in ergodic theory and measurable dynamics. The motivation for this work is that one may measure how similar two dynamical systems are by asking how much the time structure of orbits of one system must be distorted for it to become the other. Different restrictions on the allowed distortion will lead to different restricted orbit equivalence theories. These include Ornstein's Isomorphism theory, Kakutani Equivalence theory and a list of others. By putting such restrictions in an axiomatic framework, a general approach is developed that encompasses all these examples simultaneously and gives insight into how to seek further applications. The work is placed in the context of discrete amenable group actions where time is not required to be one-dimensional, making the results applicable to a much wider range of problems and examples.
The purpose of this work is to lift the notion of restricted orbit equivalence to the category of free and ergodic actions of discrete amenable groups. We mean lift in two senses. First of course we will generalize the results in, where Rudolph developed a theory of restricted orbit equivalence for ℤ-actions, and in where both authors later established a similar theory for actions of ℤd, d ≥ 1 to actions of these more general groups. However, we will also lift in the sense that we will develop the axiomatics and argument structures in what we feel is a far more natural and robust fashion. Both and were based on axiomatizations of a notion called a “size” measuring the degree of distortion of a box in ℤd caused by a permutation. It is not evident that on their common ground, ℤ-actions, these two theories agree. Hence we refer to the first as a 1-size and the second as a p-size, p for “permutation”.
Here we will establish the axiomatics of what we will simply call a size. We ask that the reader accept this new definition. In the Appendix we show that any equivalence relation that arose from a p-size will arise from a size as we define it here. The same is not done for 1-sizes, but for a slight strengthening of this axiomatics that includes all the examples in.
Copying lemmas play a pivotal role in Dye's Theorem, Vershik's Lacunary Isomorphism Theorem and most significantly in Ornstein's Isomorphism Theorem for Bernoulli shifts. The Burton–Rothstein version of this last result puts them in an even more central role as the rest of the argument becomes soft analysis. We are generalizing from this Burton-Rothstein perspective of course, making the core of our equivalence theorem rest on category. Copying lemmas will play a pivotal role for us in two contexts. First in the equivalence theorem they will play the same role as always, allowing one to copy partitions, and in our case full-group elements, from a joining of two systems into one of the two. We will also use a copying lemma as a basic tool in our development of m-entropy to show that sizes are either “entropy-preserving” or “entropy-free”.
These two applications have one fact in common. As indicated above one must copy not only partitions but full-group elements. Hence we will have to investigate how one does this. These copying lemmas will also have one very real difference. For use in the equivalence theorem one will want the copied process to have as much entropy as one can hope for, but for use in the entropy theory, one will want the copy to kill as much entropy as possible. Hence we really must give two copying lemmas.