University of St Andrews

About: University of St Andrews is a education organization based out in St Andrews, Fife, United Kingdom. It is known for research contribution in the topics: Population & Laser. The organization has 16260 authors who have published 43364 publications receiving 1636072 citations. The organization is also known as: St Andrews University & University of St. Andrews.

Looking inside the spiky bits: a critical review and conceptualisation of entrepreneurial ecosystems

Abstract: The concept of entrepreneurial ecosystems has quickly established itself as one of the latest ‘fads’ in entrepreneurship research. At face value, this kind of systemic approach to entrepreneurship offers a new and distinctive path for scholars and policy makers to help understand and foster growth-oriented entrepreneurship. However, its lack of specification and conceptual limitations has undoubtedly hindered our understanding of these complex organisms. Indeed, the rapid adoption of the concept has tended to overlook the heterogeneous nature of ecosystems. This paper provides a critical review and conceptualisation of the ecosystems concept: it unpacks the dynamics of the concept; outlines its theoretical limitations; measurement approaches and use in policy-making. It sets out a preliminary taxonomy of different archetypal ecosystems. The paper concludes that entrepreneurial ecosystems are a highly variegated, multi-actor and multi-scalar phenomenon, requiring bespoke policy interventions.

Snowball Earth climate dynamics and Cryogenian geology-geobiology

Abstract: Geological evidence indicates that grounded ice sheets reached sea level at all latitudes during two long-lived Cryogenian (58 and ≥5 My) glaciations. Combined uranium-lead and rhenium-osmium dating suggests that the older (Sturtian) glacial onset and both terminations were globally synchronous. Geochemical data imply that CO2 was 102 PAL (present atmospheric level) at the younger termination, consistent with a global ice cover. Sturtian glaciation followed breakup of a tropical supercontinent, and its onset coincided with the equatorial emplacement of a large igneous province. Modeling shows that the small thermal inertia of a globally frozen surface reverses the annual mean tropical atmospheric circulation, producing an equatorial desert and net snow and frost accumulation elsewhere. Oceanic ice thickens, forming a sea glacier that flows gravitationally toward the equator, sustained by the hydrologic cycle and by basal freezing and melting. Tropical ice sheets flow faster as CO2 rises but lose mass and become sensitive to orbital changes. Equatorial dust accumulation engenders supraglacial oligotrophic meltwater ecosystems, favorable for cyanobacteria and certain eukaryotes. Meltwater flushing through cracks enables organic burial and submarine deposition of airborne volcanic ash. The subglacial ocean is turbulent and well mixed, in response to geothermal heating and heat loss through the ice cover, increasing with latitude. Terminal carbonate deposits, unique to Cryogenian glaciations, are products of intense weathering and ocean stratification. Whole-ocean warming and collapsing peripheral bulges allow marine coastal flooding to continue long after ice-sheet disappearance. The evolutionary legacy of Snowball Earth is perceptible in fossils and living organisms.

Motor Control and Learning

Abstract: Motor control is concerned with the processes that allow the central nervous system to interact with the world. How we learn to control movement is central to our understanding of all human behavior. Keywords: movement; speed–accuracy; sensory feedback; training; kinematics

Increasing the conductivity of crystalline polymer electrolytes

Abstract: Polymer electrolytes consist of salts dissolved in polymers (for example, polyethylene oxide, PEO), and represent a unique class of solid coordination compounds. They have potential applications in a diverse range of all-solid-state devices, such as rechargeable lithium batteries, flexible electrochromic displays and smart windows1,2,3,4,5. For 30 years, attention was focused on amorphous polymer electrolytes in the belief that crystalline polymer:salt complexes were insulators. This view has been overturned recently by demonstrating ionic conductivity in the crystalline complexes PEO6:LiXF6 (X = P, As, Sb); however, the conductivities were relatively low6,7. Here we demonstrate an increase of 1.5 orders of magnitude in the conductivity of these materials by replacing a small proportion of the XF6- anions in the crystal structure with isovalent N(SO2CF3)2- ions. We suggest that the larger and more irregularly shaped anions disrupt the potential around the Li+ ions, thus enhancing the ionic conductivity in a manner somewhat analogous to the AgBr1-xIx ionic conductors8. The demonstration that doping strategies can enhance the conductivity of crystalline polymer electrolytes represents a significant advance towards the technological exploitation of such materials.