title: Continuous Beam Steering Through Broadside Using Asymmetrically Modulated Goubau Line Leaky-Wave Antennas

authors: Tang, Xiao-Lan

abstract: Goubau line is a single-conductor transmission line, featuring easy integration and low-loss transmission properties. Here, we propose a periodic leaky-wave antenna (LWA) based on planar Goubau transmission line on a thin dielectric substrate. The leaky-wave radiations are generated by introducing periodic modulations along the Goubau line. In this way, the surface wave, which is slow-wave mode supported by the Goubau line, achieves an additional momentum and hence enters the fast-wave region for radiations. By employing the periodic modulations, the proposed Goubau line LWAs are able to continuously steer the main beam from backward to forward within the operational frequency range. However, the LWAs usually suffer from a low radiation efficiency at the broadside direction. To overcome this drawback, we explore both transversally and longitudinally asymmetrical modulations to the Goubau line. Theoretical analysis, numerical simulations and experimental results are given in comparison with the symmetrical LWAs. It is demonstrated that the asymmetrical modulations significantly improve the radiation efficiency of LWAs at the broadside. Furthermore, the measurement results agree well with the numerical ones, which experimentally validates the proposed LWA structures. These novel Goubau line LWAs, experimentally demonstrated and validated at microwave frequencies, show also great potential for millimeter-wave and terahertz systems.

text: Continuous Beam Steering Through Broadside Using Asymmetrically Modulated Goubau Line Leaky-Wave Antennas Goubau line is a single-conductor transmission line, featuring easy integration and low-loss transmission properties. Here, we propose a periodic leaky-wave antenna (LWA) based on planar Goubau transmission line on a thin dielectric substrate. The leaky-wave radiations are generated by introducing periodic modulations along the Goubau line. In this way, the surface wave, which is slow-wave mode supported by the Goubau line, achieves an additional momentum and hence enters the fast-wave region for radiations. By employing the periodic modulations, the proposed Goubau line LWAs are able to continuously steer the main beam from backward to forward within the operational frequency range. However, the LWAs usually suffer from a low radiation efficiency at the broadside direction. To overcome this drawback, we explore both transversally and longitudinally asymmetrical modulations to the Goubau line. Theoretical analysis, numerical simulations and experimental results are given in comparison with the symmetrical LWAs. It is demonstrated that the asymmetrical modulations significantly improve the radiation efficiency of LWAs at the broadside. Furthermore, the measurement results agree well with the numerical ones, which experimentally validates the proposed LWA structures. These novel Goubau line LWAs, experimentally demonstrated and validated at microwave frequencies, show also great potential for millimeter-wave and terahertz systems.

year: 2017-12-01

title: Performance implications of active management of institutional mutual funds

authors: Bird, Ron

subjects: institutional mutual funds

abstract: We use information on institutional US mutual funds to examine the performance implications of the decisions they make when actively implementing their investment processes. Our findings show that the success of active fund managers' stock selection decisions is influenced both by the aggressiveness with which they implement their processes and also the style tilts incorporated into their active positions. Our findings provide useful insights into both where one might best look when choosing an active manager and also suggest possible profitable investment strategies.

text: Performance implications of active management of institutional mutual funds We use information on institutional US mutual funds to examine the performance implications of the decisions they make when actively implementing their investment processes. Our findings show that the success of active fund managers' stock selection decisions is influenced both by the aggressiveness with which they implement their processes and also the style tilts incorporated into their active positions. Our findings provide useful insights into both where one might best look when choosing an active manager and also suggest possible profitable investment strategies.

year: 2013

title: Pōwhiri: A framing to strengthen bicultural belonging for refugee children and families in early childhood education

authors: Rameka, Lesley Kay

subjects: bicultural belonging

abstract: A crucial task for refugee families and children who settle in Aotearoa New Zealand is to develop a sense of belonging in that place, time and environment. Belonging is a basic human need. It is a driving force for learning how to be and behave in a new setting and a springboard for participation (Guo & Dalli, 2016; Sumsion & Wong, 2011). As a concept, ‘belonging’ is acknowledged to be multifaceted, culturally-determined, and complex. This article focuses on phase two of the Refugee families in early childhood education: Constructing pathways to belonging research project, which involved trialling and evaluating, with early childhood services, the pōwhiri (Māori ceremony of welcome) framing, developed in phase one of the research. The framing offers concepts to enable understanding of the phases and processes for refugee and immigrant families to develop a sense of bicultural belonging in Aotearoa New Zealand. Pōwhiri is the traditional Māori ceremony of welcome or ritual of encounter, performed across Aotearoa New Zealand, by the host people to welcome visitors to their region. Pōwhiri is explained in this article as a physical process following standard phases, with each phase including metaphorical understandings.

text: Pōwhiri: A framing to strengthen bicultural belonging for refugee children and families in early childhood education A crucial task for refugee families and children who settle in Aotearoa New Zealand is to develop a sense of belonging in that place, time and environment. Belonging is a basic human need. It is a driving force for learning how to be and behave in a new setting and a springboard for participation (Guo & Dalli, 2016; Sumsion & Wong, 2011). As a concept, ‘belonging’ is acknowledged to be multifaceted, culturally-determined, and complex. This article focuses on phase two of the Refugee families in early childhood education: Constructing pathways to belonging research project, which involved trialling and evaluating, with early childhood services, the pōwhiri (Māori ceremony of welcome) framing, developed in phase one of the research. The framing offers concepts to enable understanding of the phases and processes for refugee and immigrant families to develop a sense of bicultural belonging in Aotearoa New Zealand. Pōwhiri is the traditional Māori ceremony of welcome or ritual of encounter, performed across Aotearoa New Zealand, by the host people to welcome visitors to their region. Pōwhiri is explained in this article as a physical process following standard phases, with each phase including metaphorical understandings.

year: 2022