Size-dependence of Strong-Coupling Between Nanomagnets and Photonic Cavities

The coherent dynamics of a coupled photonic cavity and a nanomagnet is explored as a function of nanomagnet size. For sufficiently strong coupling eigenstates involving highly entangled photon and spin states are found, which can be combined to create coherent states. As the size of the nanomagnet increases its coupling to the photonic mode also monotonically increases, as well as the number of photon and spin states involved in the system's eigenstates. For small nanomagnets the crystalline anisotropy of the magnet strongly localized the eigenstates in photon and spin number, quenching the potential for coherent states. For a sufficiently large nanomagnet the macrospin approximation breaks down and different domains of the nanomagnet may couple separately to the photonic mode. Thus the optimal nanomagnet size is just below the threshold for failure of the macrospin approximation.Comment: 10 pages, 7 figure

Relaxation Mechanism for Ordered Magnetic Materials

We have formulated a relaxation mechanism for ferrites and ferromagnetic metals whereby the coupling between the magnetic motion and lattice is based purely on continuum arguments concerning magnetostriction. This theoretical approach contrasts with previous mechanisms based on microscopic formulations of spin-phonon interactions employing a discrete lattice. Our model explains for the first time the scaling of the intrinsic FMR linewidth with frequency, and 1/M temperature dependence and the anisotropic nature of magnetic relaxation in ordered magnetic materials, where M is the magnetization. Without introducing adjustable parameters our model is in reasonable quantitative agreement with experimental measurements of the intrinsic magnetic resonance linewidths of important class of ordered magnetic materials, insulator or metals

Redirecting research efforts on the diversification-performance linkage: The search for synergy

We review the literature on the diversification-performance (D-P) relationship to a) propose that the time is ripe for a renewed attack on understanding the relationship between diversification and firm performance, and b) outline a new approach to attacking the question. Our paper makes four main contributions. First, through a review of the literature we establish the inherent complexities in the D-P relationship and the methodological challenges confronted by the literature in reaching its current conclusion of a non-linear relationship between diversification and performance. Second, we argue that to better guide managers the literature needs to develop along a complementary path – whereas past research has often focused on answering the big question of does diversification affect firm performance, this second path would focus more on identifying the precise micro-mechanisms through which diversification adds or subtracts value. Third, we outline a new approach to the investigation of this topic, based on (a) identifying the precise underlying mechanisms through which diversification affects performance; (b) identifying performance outcomes that are “proximate” to the mechanism that the researcher is studying, and (c) identifying an appropriate research design that can enable a causal claim. Finally, we outline a set of directions for future research

Extreme rainfall events alter the trophic structure in bromeliad tanks across the Neotropics

Changes in global and regional precipitation regimes are among the most pervasive components of climate change. Intensification of rainfall cycles, ranging from frequent downpours to severe droughts, could cause widespread, but largely unknown, alterations to trophic structure and ecosystem function. We conducted multi-site coordinated experiments to show how variation in the quantity and evenness of rainfall modulates trophic structure in 210 natural freshwater microcosms (tank bromeliads) across Central and South America (18°N to 29°S). The biomass of smaller organisms (detritivores) was higher under more stable hydrological conditions. Conversely, the biomass of predators was highest when rainfall was uneven, resulting in top-heavy biomass pyramids. These results illustrate how extremes of precipitation, resulting in localized droughts or flooding, can erode the base of freshwater food webs, with negative implications for the stability of trophic dynamics

Repensando redes estratégicas

The political dispute with the field of organization studies (OS) for leadership in research and education in business administration in the US and the proliferation of schools of thought in the 1980s resulted in serious questioning of the relevance of the field of strategy. Neoliberal globalization and its discourses pushed strategists of big corporations and academics to build the relevance of the area through increasing specialization and internationalization, but the dominant literature still ignores power and political issues and downplays government organizations. This helps explain the underdevelopment of research in strategic networks, the translation gap faced by business schools in the Anglo-American world, and the resistance in Brazil and other countries to the dominant literature. Analysis shows that research in strategic networks in emerging economies should make visible power and political issues, particularly from a critical perspective on asymmetries enhanced by the advance of neoliberalism, and produce knowledge that is relevant to strategists from both business firms and government and also society at large. In Brazil, researchers from strategy and OS should value and reinforce the proximity of these fields, and foster interdisciplinary developments with geography, global sociology and international relations and in particular with the literature in networks based on international political economy.A disputa política com a área de estudos organizacionais (EO) pela liderança em pesquisa e ensino em administração iniciada nos anos 1960 nos Estados Unidos e a proliferação de escolas de pensamento nos anos 1980 resultaram em questionamentos acerca da relevância da área de estratégia. A globalização neoliberal e seus discursos impulsionaram a construção da relevância da área por meio de crescente especialização e internacionalização; mas questões de poder e política continuam sendo desprezadas pela literatura dominante. Este quadro ajuda a explicar o subdesenvolvimento de pesquisa em redes estratégicas, o problema de relevância das escolas de negócios no mundo anglo-americano, e a resistência de pesquisadores no Brasil e outros países à literatura dominante. A análise mostra que pesquisas em redes estratégicas em economias emergentes devem contemplar questões de poder e política, em perspectiva crítica que desafia assimetrias acentuadas pelo avanço do neoliberalismo, para produzir conhecimento relevante para estrategistas de empresas e do governo e para a sociedade. No Brasil pesquisadores das áreas de estratégia e de EO devem valorizar e reforçar a proximidade entre essas áreas e promover desenvolvimentos interdisciplinares com áreas como geografia, sociologia global e relações internacionais, e em especial com a literatura de redes baseada em economia política internacional

Designing an environmental flow framework for impounded river systems through modelling of invertebrate habitat quality

Many rivers have undergone flow modification by impoundments to provide services such as water supply and hydropower. There is an established consensus that typical modified flow regimes do not sufficiently cater to the needs of downstream ecosystems, and more must be done to understand and mitigate their associated impacts. This study presents a novel, transferable framework by which a small-scale impoundment in North West England is assessed through the use of linked hydro-ecological modelling in SRH-2D and CASiMiR, utilising flow velocity measurements and macroinvertebrate sampling data. Model predictions of habitat quality were supplemented by established ecological principles such as the importance of flow heterogeneity. Results are used to design environmental flow regimes, with the aim of improving ecological metrics whilst considering conflicting water demands. Based on an analysis of historical flow records, the implementation of designer flows over a 12 month period demonstrated increased peak species habitat qualities of 23–26%, characteristics such as flow heterogeneity were more naturalised, and 22% less water was released from the impoundment. Should outcomes be validated by in-stream flow experiment, there is great potential for further development and application of this method, including regional transferability for the rapid designation of environmental flows across a number of sites of similar magnitude and geography