Evolution of interdisciplinarity in biodiversity science

The study of biodiversity has grown exponentially in the last thirty years in response to demands for greater understanding of the function and importance of Earth's biodiversity and finding solutions to conserve it. Here, we test the hypothesis that biodiversity science has become more interdisciplinary over time. To do so, we analyze 97,945 peer‐reviewed articles over a twenty‐two‐year time period (1990–2012) with a continuous time dynamic model, which classifies articles into concepts (i.e., topics and ideas) based on word co‐occurrences. Using the model output, we then quantify different aspects of interdisciplinarity: concept diversity, that is, the diversity of topics and ideas across subdisciplines in biodiversity science, subdiscipline diversity, that is, the diversity of subdisciplines across concepts, and network structure, which captures interactions between concepts and subdisciplines. We found that, on average, concept and subdiscipline diversity in biodiversity science were either stable or declining, patterns which were driven by the persistence of rare concepts and subdisciplines and a decline in the diversity of common concepts and subdisciplines, respectively. Moreover, our results provide evidence that conceptual homogenization, that is, decreases in temporal β concept diversity, underlies the observed trends in interdisciplinarity. Together, our results reveal that biodiversity science is undergoing a dynamic phase as a scientific discipline that is consolidating around a core set of concepts. Our results suggest that progress toward addressing the biodiversity crisis via greater interdisciplinarity during the study period may have been slowed by extrinsic factors, such as the failure to invest in research spanning across concepts and disciplines. However, recent initiatives such as the Intergovernmental Science‐Policy Platform on Biodiversity and Ecosystem Services (IPBES) may attract broader support for biodiversity‐related issues and hence interdisciplinary approaches to address scientific, political, and societal challenges in the coming years

Intracavity terahertz generation inside a high-energy ultrafast soliton fiber laser

Intracavity terahertz emission inside a high-energy ultrafast Yb-doped fiber laser is presented. The terahertz radiation is generated by a transient photocurrent induced at the surface of a saturable InGaAs multiquantum well grown by molecular beam epitaxy on top of a semiconductor Bragg reflector. This device simultaneously works as the saturable absorber mirror for initiating and managing the passive mode locking required for the ultrashort pulse operation of the laser system. The maximum terahertz average power achieved is 4.2 mu W, which reveals a net conversion efficiency of 3.1x10(-5)

Microlens coupled interdigital photoconductive switch

A large-area terahertz emitter based on an interdigital finger electrode photoconductive switch on low-temperature grown GaAs attached to a hexagonal microlens array is demonstrated. The hexagonal arranged microlenses direct the incident IR excitation pulses into specified electrode gaps, resulting in constructive interference in the terahertz far field. Using a Ti:sapphire oscillator running at 80 MHz with 150 fs pulses, 6.5 mu m THz average power at 540 mW optical excitation is obtained. The maximum IR-to-terahertz conversion efficiency achieved is >= 1.35x10(-5)

Predictable caches in real-time systems

Modern processors with an extensive cache structure are considered not to be useful in real-time systems since task switches disrupt cache working sets and hence make execution times unpredictable. This paper describes a technique to constrain and an experimental environment to measure worst-case penalties imposed on realtime tasks due to external cache interference. With the described technique, caches can be partitioned and partitions can be assigned to tasks for their exclusive use. Using the techniques, a simple filter algorithm commonly used in real-time systems is analysed and worst-case penalties are determined for three different, widely used cache architectures. Some insights regarding the impact of cache architectures on worst-case execution are described. (orig.)Available from TIB Hannover: RR 7268(96,1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman