Low-mass spectroscopic binaries in the Hyades: a candidate brown dwarf companion

We have used the HIRES echelle spectrograph in the Keck I telescope to obtain high-resolution spectroscopy of 51 late-type M dwarfs in the Hyades cluster. Cross-correlating the calibrated data against spectra of white dwarfs allows us to determine heliocentric velocities with an accuracy of +/- 0.3 km/s. Twenty seven stars were observed at two epochs in 1997; two stars, RHy 42 and RHy 403, are confirmed spectroscopic binaries. RHY 42 is a double-lined, equal-mass system; RHy 403 is a single-lined, short-period binary, P ~ 1.275 days. RHy 403A has an absolute magnitude of M_I = 10.85, consistent with a mass of 0.15 M(Sun). The systemic mass function has a value of 0.0085, which, combined with the non-detection of a secondary peak in the cross-correlation function, implies 0.095 > M_2 > 0.06 M (Sun), and the strong possibility that the companion is the first Hyades brown dwarf to be identified. Unfortunately, the maximum expected angular separation in the system is only 0.25 mas. Five other low-mass Hyads are identified as possible spectroscopic binaries, based either on repeat observations or comparison between the observed radial velocity and the value expected for Hyades cluster members. Combined with HST imaging data, we infer a binary fraction between 23 and 30 . All of the stars are chromospherically active. RHy 281 was caught in mid-flare and, based on that detection, we estimate a flaring frequency of 2.5% for low-mass Hyades stars. Nine stars have rotational velocities, v sin(i), exceeding 20 km/s and most of the sample have detectable rotation. We examine the H-alpha emission characteristics of low-mass cluster members and show that there is no evidence for a correlation with rotation.Comment: accepted for MNRAS, 10 figures & 8 tables embedded in tex

Toward a Theory of Public Entrepreneurship

This paper explores innovation, experimentation, and creativity in the public domain and in the public interest. Researchers in various disciplines have studied public entrepreneurship, but there is little work in management and economics on the nature, incentives, constraints and boundaries of entrepreneurship directed to public ends. We identify a framework for analyzing public entrepreneurship and its relationship to private entrepreneurial behavior. We submit that public and private entrepreneurship share essential features but differ critically regarding the definition and measurement of objectives, the nature of the selection environment, and the opportunities for rent-seeking. We describe four levels of analysis for studying public entrepreneurship, provide examples, and suggest new research directions.Entrepreneurship, public administration, political economy, institutions, transaction costs

Resources, Capabilities, and Routines in Public Organization

States, state agencies, multilateral agencies, and other non-market actors are relatively under-studied in the strategic entrepreneurship literature. While important contributions examining public decision makers have been made within the agency-theoretic and transaction-cost traditions, there is little research that builds on resource-based, dynamic capabilities, and behavioral approaches to organizations. Yet public organizations can be usefully characterized as stocks of physical, organizational, and human resources; they interact with other organizations in pursuing a type of competitive advantage; they can possess excess capacity, and may grow and diversify in part according to Penrosean (dynamic) capabilities and behavioral logic. Public organizations may be managed as stewards of resources, capabilities, and routines. This paper shows how resource-based, (dynamic) capabilities, and behavioral approaches shed light on the nature and governance of public organizations and suggests a research agenda for public entrepreneurship that reflects insights gained from applying strategic management theory to public organization.

Toward a Theory of Public Entrepreneurship

This paper explores innovation, experimentation, and creativity in the public domain and in the public interest. Researchers in various disciplines have studied public entrepreneurship, but there is little research specifically on the nature, incentives and constraints of public entrepreneurship to innovate in the public interest. We begin by extending concepts of the entrepreneurial firm to include greater interactions in the public domain, and then turn to the role of entrepreneurial firms in fostering institutional change. This focus points toward opportunities for integrating transaction-costs, political and international business theories to achieve a more refined institutional theory of firm-government interactions that incorporates entrepreneurial agency as a principal mechanism for innovating in the fulfillment of public and private interests.

Adolescent physical self-perceptions, sport/exercise and lifestyle physical activity

Purpose – Domain and sub-domain physical self-perceptions have been associated with adolescent moderate intensity physical activity although the association with different types of adolescent moderate intensity physical activity remains unclear. This study seeks to examine the relationship between personal self-perceptions and adolescent sport/exercise and lifestyle moderate intensity physical activity frequency. Design/methodology/approach – A total of 122, 13-to-14 year-old, English adolescents from Leeds, West Yorkshire (58 boys and 64 girls) had their personal self-perceptions, sport/exercise and lifestyle moderate intensity physical activity assessed. Findings – No significant positive relationships were found between boys' personal self-perceptions and lifestyle moderate intensity physical activity. However, a range of weak (r?=?0.34-0.42) but significant relationships (p?<?0.01) were found between personal self perceptions and boys' sport/exercise frequency. In contrast, only perceptions of strength competence were significantly related to girls' sport/exercise frequencies (r?=?0.28; p?<?0.05), while all personal self perceptions scales were significantly related to girls' lifestyle moderate intensity physical activity (r?=?0.26-0.32; p?<?0.05). Research limitations/implications – The use of correlation analyses by this study placed limitations on the extent to which cause-effect relationships were established. Furthermore, girls' sport/exercise was poorly distributed, which may have led to the non-significant relationship found between this activity type and personal self-perceptions. The presence of a significant relationship between these two variables should therefore not be discounted. Originality/value – This study seems to be the first to investigate and identify variations in the personal self-perceptions – moderate intensity physical activity relationship relative to activity type. Although more research is required, findings have implications for practitioners aiming to tailor physical activity interventions to this group and researchers aiming to match specific correlates to different types of adolescent physical activity

Mental toughness in sport: Motivational antecedents and associations with performance and psychological health

We argue that basic psychological needs theory (BPNT) offers impetus to the value of mental toughness as a mechanism for optimizing human functioning. We hypothesized that psychological needs satisfaction (thwarting) would be associated with higher (lower) levels of mental toughness, positive affect, and performance and lower (higher) levels of negative affect. We also expected that mental toughness would be associated with higher levels of positive affect and performance and lower levels of negative affect. Further, we predicted that coaching environments would be related to mental toughness indirectly through psychological needs and those psychological needs would indirectly relate with performance and affect through mental toughness. Adolescent cross-country runners (136 male and 85 female, Mage = 14.36) completed questionnaires pertaining to BPNT variables, mental toughness, and affect. Race times were also collected. Our findings supported our hypotheses. We concluded that BPNT is generative in understanding some of the antecedents and consequences of mental toughness and is a novel framework useful for understanding mental toughness