151 research outputs found

    Rate Coefficients for Reactions of Ethynyl Radical (C2H) With HCN and CH3CN: Implications for the Formation of Comples Nitriles on Titan

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    Rate coefficients for the reactions of C2H + HCN yields products and C2H + CH3CN yields products have been measured over the temperature range 262-360 K. These experiments represent an ongoing effort to accurately measure reaction rate coefficients of the ethynyl radical, C2H, relevant to planetary atmospheres such as those of Jupiter and Saturn and its satellite Titan. Laser photolysis of C2H2 is used to produce C2H, and transient infrared laser absorption is employed to measure the decay of C2H to obtain the subsequent reaction rates in a transverse flow cell. Rate constants for the reaction C2H + HCN yields products are found to increase significantly with increasing temperature and are measured to be (3.9-6.2) x 10(exp 13) cm(exp 3) molecules(exp -1) s(exp -1) over the temperature range of 297-360 K. The rate constants for the reaction C2H + CH3CN yields products are also found to increase substantially with increasing temperature and are measured to be (1.0-2.1) x 10(exp -12) cm(exp 3) molecules(exp -1) s(exp -1) over the temperature range of 262-360 K. For the reaction C2H + HCN yields products, ab initio calculations of transition state structures are used to infer that the major products form via an addition/elimination pathway. The measured rate constants for the reaction of C2H + HCN yields products are significantly smaller than values currently employed in photochemical models of Titan, which will affect the HC3N distribution

    The business case for women leaders: Meta-analysis, research critique, and path forward

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    Since the 1990s, a growing body of research has sought to quantify the relationship between women’s representation in leadership positions and organizational financial performance. Commonly known as the “business case” for women’s leadership, the idea is that having more women leaders is good for business. Through meta-analysis ( k = 78, n = 117,639 organizations) of the direct effects of women’s representation in leadership (as CEOs, on top management teams, and on boards of directors) on financial performance, and tests that proxy theoretical arguments for moderated relationships, we call attention to equivocal findings. Our results suggest women’s leadership may affect firm performance in general and sales performance in particular. And women’s leadership—overall and, specifically, the presence of a female CEO—is more likely to positively relate to firms’ financial performance in more gender egalitarian cultures. Yet taking our findings as a whole, we argue that commonly used methods of testing the business case for women leaders may limit our ability as scholars to understand the value that women bring to leadership positions. We do not advocate that the business case be abandoned altogether but, rather, improved and refined. We name exemplary research studies to show how different perspectives on gender, alternative conceptualizations of value, and the specification of underlying mechanisms linking leadership to performance can generate changes in both the dominant ontology and the epistemology underlying this body of research.</jats:p

    On the pp-supports of a holonomic D\mathcal{D}-module

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    For a smooth variety YY over a perfect field of positive characteristic, the sheaf DYD_Y of crystalline differential operators on YY (also called the sheaf of PDPD-differential operators) is known to be an Azumaya algebra over TY,T^*_{Y'}, the cotangent space of the Frobenius twist YY' of Y.Y. Thus to a sheaf of modules MM over DYD_Y one can assign a closed subvariety of TY,T^*_{Y'}, called the pp-support, namely the support of MM seen as a sheaf on TY.T^*_{Y'}. We study here the family of pp-supports assigned to the reductions modulo primes pp of a holonomic D\mathcal{D}-module. We prove that the Azumaya algebra of differential operators splits on the regular locus of the pp-support and that the pp-support is a Lagrangian subvariety of the cotangent space, for pp large enough. The latter was conjectured by Kontsevich. Our approach also provides a new proof of the involutivity of the singular support of a holonomic D\mathcal{D}-module, by reduction modulo p.p.Comment: The article has been rewritten with much improved exposition as well as some additional results, e.g. Corollary 6.3.1. This is the final version, accepted for publication in Inventiones Mathematica

    Duality in the flat cohomology of curves

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46600/1/222_2005_Article_BF01390135.pd

    Work-life balance in the police: the development of a self-management competency framework

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    Purpose Addressing a gap in the current work–life balance (WLB) literature regarding individual-focused approaches to inform interventions, we elicited behaviors used to self-manage WLB to draw up a competency-based WLB framework for relevant learnable knowledge, skills, and abilities (KSAs; Hoffmann, Eur J Ind Train 23:275–285, 1999) and mapping this against extant WLB frameworks. Design/Methodology/Approach Our participants were from a major UK police force, which faces particular challenges to the work–life interface through job demands and organizational cutbacks, covering a range of operational job roles, including uniformed officers and civilian staff. We took a mixed methods approach starting with semi-structured interviews to elicit 134 distinct behaviors (n = 20) and used a subsequent card sort task (n = 10) to group these into categories into 12 behavioral themes; and finally undertook an online survey (n = 356) for an initial validation. Findings Item and content analysis reduced the behaviors to 58, which we analyzed further. A framework of eight competencies fits the data best; covering a range of strategies, including Boundary Management, Managing Flexibility, and Managing Expectations. Implications The WLB self-management KSAs elicited consist of a range of solution-focused behaviors and strategies, which could inform future WLB-focused interventions, showing how individuals may negotiate borders effectively in a specific environment. Originality/Value A competence-based approach to WLB self-management is new, and may extend existing frameworks such as Border Theory, highlighting a proactive and solution-focused element of effective behaviors

    How does ethical leadership trickle down? Test of an integrative dual-process model

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    Although the trickle-down effect of ethical leadership has been documented in the literature, its underlying mechanism still remains largely unclear. To address this gap, we develop a cross-level dual-process model to explain how the effect occurs. Drawing on social learning theory, we hypothesize that the ethical leadership of high-level managers could cascade to middle-level supervisors via its impact on middle-level supervisors’ two ethical expectations. Using a sample of 69 middle-level supervisors and 381 subordinates across 69 sub-branches from a large banking firm in China, we found that middle-level supervisors’ ethical efficacy expectation and unethical behavior–punishment expectation (as one form of ethical outcome expectations) accounted for the trickle-down effect. The explanatory role of middle-level supervisors’ ethical behavior–reward expectation (as the other form of ethical outcome expectations), however, was not supported. The theoretical and practical implications are discussed

    The business case for women leaders : meta-analysis, research critique, and path forward

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    Since the 1990s, a growing body of research has sought to quantify the relationship between women’s representation in leadership positions and organizational financial performance. Commonly known as the “business case” for women’s leadership, the idea is that having more women leaders is good for business. Through meta-analysis (k = 78, n = 117,639 organizations) of the direct effects of women’s representation in leadership (as CEOs, on top management teams, and on boards of directors) on financial performance, and tests that proxy theoretical arguments for moderated relationships, we call attention to equivocal findings. Our results suggest women’s leadership may affect firm performance in general and sales performance in particular. And women’s leadership—overall and, specifically, the presence of a female CEO—is more likely to positively relate to firms’ financial performance in more gender egalitarian cultures. Yet taking our findings as a whole, we argue that commonly used methods of testing the business case for women leaders may limit our ability as scholars to understand the value that women bring to leadership positions. We do not advocate that the business case be abandoned altogether but, rather, improved and refined. We name exemplary research studies to show how different perspectives on gender, alternative conceptualizations of value, and the specification of underlying mechanisms linking leadership to performance can generate changes in both the dominant ontology and the epistemology underlying this body of research.A grant (No. 80588) provided by the National Research Foundation of South Africa.https://journals.sagepub.com/home/jomhj2019Human Resource Managemen
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