Stream-orbit misalignment I: The dangers of orbit-fitting

Tidal streams don't, in general, delineate orbits. A stream-orbit misalignment is expected to lead to biases when using orbit-fitting to constrain models for the Galactic potential. In this first of two papers we discuss the expected magnitude of the misalignment and the resulting dangers of using orbit-fitting algorithms to constrain the potential. We summarize data for known streams which should prove useful for constraining the Galactic potential, and compute their actions in a realistic Galactic potential. We go on to discuss the formation of tidal streams in angle-action space, and explain why, in general, streams do not delineate orbits. The magnitude of the stream-orbit misalignment is quantified for a logarithmic potential and a multi-component Galactic potential. Specifically, we focus on the expected misalignment for the known streams. By introducing a two-parameter family of realistic Galactic potentials we demonstrate that assuming these streams delineate orbits can lead to order one errors in the halo flattening and halo-to-disc force ratio at the Sun. We present a discussion of the dependence of these results on the progenitor mass, and demonstrate that the misalignment is mass-independent for the range of masses of observed streams. Hence, orbit-fitting does not yield better constraints on the potential if one uses narrower, lower-mass streams.Comment: 13 pages, 7 figures, accepted for publication in MNRA

Stream-orbit misalignment II: A new algorithm to constrain the Galactic potential

In the first of these two papers we demonstrated that assuming streams delineate orbits can lead to order one errors in potential parameters for realistic Galactic potentials. Motivated by the need for an improvement on orbit-fitting, we now present an algorithm for constraining the Galactic potential using tidal streams without assuming that streams delineate orbits. This approach is independent of the progenitor mass so is valid for all observed tidal streams. The method makes heavy use of angle-action variables and seeks the potential which recovers the expected correlations in angle space. We demonstrate that the method can correctly recover the parameters of a simple two-parameter logarithmic potential by analysing an N-body simulation of a stream. We investigate the magnitude of the errors in observational data for which the method can still recover the correct potential and compare this to current and future errors in data. The errors in the observables of individual stars for current and near future data are shown to be too large for the direct use of this method, but when the data are averaged in bins on the sky, the resulting averaged data are accurate enough to constrain correctly the potential parameters for achievable observational errors. From pseudo-data with errors comparable to those that will be furnished in the era of Gaia (20 per cent distance errors, 1.2 mas/yr proper motion errors, and 10 km/s line-of-sight velocity errors) we recover the circular velocity, V_c=220 km/s, and the flattening of the potential, q=0.9, to be V_c=223+/-10km/s and q=0.91+/-0.09.Comment: 11 pages, 5 figures, accepted for publication in MNRA

Verifiable and Non-Verifiable Anonymous Mechanisms for Regulating a Polluting Monopolist

Optimal regulation of a polluting natural monopolist must correct for both external damages and market power to achieve a social optimum. Existing non-Bayesian regulatory methods require knowledge of the demand function, while Bayesian schemes require knowledge of the underlying cost distribution. We introduce mechanisms adapted to use less information. Our Price-based Subsidy (PS) mechanisms give the firm a transfer that matches or approximates the incremental surplus generated each period. The regulator need not observe the abatement activity or know the demand, cost, or damage functions of the firm. All of the mechanisms induce the firm to price at marginal social cost, either immediately or asymptotically.surplus subsidy schemes, polluting monopolist, verifiable regulatory mechanisms

Reconsidering Missouri’s Warrant Suppression Standard

The search warrant is a foundational component of the American criminal justice process. Designed to limit and prevent overreach by police and other law enforcement entities, the framers of the Fourth Amendment of the United States Constitution sought to use warrants as a tool to control the scope and breadth of searches and seizures of private property. The Fourth Amendment’s warrant requirements are a vital check on the proactive and ever-growing police efforts of state and federal authorities

Teaching musicianship to singers in a high school choral program: a portrait of three choral directors and their pedagogies

The purpose of this study was to examine the teaching of musicianship in a high school chorus, and explore the pedagogies of three high school choral directors. Using the praxial theory of music education (Elliott & Silverman, 2015) as a framework and a multiple-case study design with elements of portraiture, I developed case studies of three high school choral directors that included musicianship instruction as a regular part of their rehearsal activities. Research questions addressed: (a) the ways high school choral directors address and assess performing-and-listening in the rehearsal to build the musicianship of their singers through sight-singing, audiation, performance practice, and aesthetic elements; (b) the ways high school choral directors address conducting-and-listening in the rehearsal to build the musicianship of their singers; and (c) the ways high school choral directors foster musical creativity of their singers as part of a plan to build their musicianship. The primary means of data collection were interviews, rehearsal observations, and document review. I conducted observations using the rehearsal planning model advocated by Abrahams and John (2015) as a guidepost. Results indicate that the development of musicianship among high school choral students does not rest exclusively on instruction in areas such as sight-singing, music theory, performance practice, piano proficiency, and vocal technique, but rather through the values asserted by Elliott (1995) and Elliott and Silverman (2015), which serve as the foundation of music education: self-growth, self-knowledge, and the emotional experience of musicing and musical enjoyment. Implications for music education include incorporating constructivist strategies in instruction, moving toward student-centered rehearsals, and devoting meaningful time to listening and assessment in order to empower student musicianship

Indigenous Citizens and Black Republicans: Continuities and Evolutions of Subalterns’ Political Visions and Repertoires in Post-independence Colombia and Mexico

This essay focuses on how Indigenous peoples in Colombia and Mexico sought to create a distinct politics, in which they could protect their colonial identities and local customs, within the new independent and republican nation-states of the Americas. Indigenous communities succeed in combining universal republican citizenship and particular colonial identities, maintaining more of a connection with the past, but nevertheless creating innovative solutions to adapt to the republican present. In contrast, popular African-Colombian actors eagerly embraced the possibilities of citizenship in new republican nation states, seeking to abandon a colonial identity associated with slavery. Both Afro-Colombians and Indígenas adapted traditional political practices, such as petitioning, in intellectually creative ways, to advance their interests and political visions after the Age of Revolution

Fixation on a Beneficially Aroused Consciousness in the Game Situation, Contingent Upon Hypnosis, in Soccer Players

The purpose of this research was to systematically regulate the sport arousal state of soccer players. Hypnosis viewed as an alternate state of consciousness was the vehicle to the beneficial sport arousal state. Once in an hypnotic state, a post hypnotic suggestion was utilized to reproduce that beneficial sport arousal state as players stepped upon the soccer field. The focus was two-fold: First, to determine whether or not a benefical sport arousal state could be attained within the hypnotic state; and secondly, wheather or not a beneficial sport arousal state could be reproduced by post-hypnotic suggestion for a game situation

Similarities and Differences in the Argumentative Characteristics of the Official Brexit Campaigns

This paper adds to the growing empirical literature surrounding the UK's vote to leave the European Union. Specifically, a series of quantitative and qualitative textual analysis tools are implemented on a corpus consisting of the websites of Vote Leave (VL) and Britain Stronger in Europe (BSE). By breaking down argumentative text into two components, this paper attempts to characterise how the two official campaigns differ in the information they choose to convey (or “focus"), and the style by which this information is conveyed. To analyse variation in focus, a structural topic model and thematic analysis of elementary context units are conducted with the inclusion of document-level metadata. This is then compared to survey data and their potential effectiveness is considered. To study the style of information transmission, an analysis of sentiment is used to calculate sentence-level polarity scores. An unambiguous thematic divide is uncovered with BSE employing a “focussed" approach by singling out topics related to the economy, whereas VL chose a “scattershot" approach by spreading their resources across a broader range of themes. The thematic analysis uncovers little reciprocity in most major areas — a notable exception being public services, which acted as a battleground. BSE's focussed approach allowed it to target the most influential topic for the electorate, but despite this, VL's approach led to a greater targeted proportion. A sentiment analysis yields two results: (A) the variability in sentence-level polarity scores was consistent across campaigns, and (2) BSE's website had a significantly greater mean score