Glossopteris‐type leaves are the most abundant floristic element from the Gondwanan continent and are recorded throughout the Permian, which was a period of extreme icehouse‐to‐hothouse climatic global change. Fossil leaf traits can be useful for the reconstruction of palaeoenvironments and identification of climatic changes throughout geological time, but the conservative morphology of Glossopteris leaves has thus far made them difficult to use for this purpose. If the characters of Glossopteris can be better quantified then it should make them useful for tracking environmental changes over a wide geographical area and over a long time interval. Venation density is a highly variable leaf trait that might be useful for this purpose. This trait can be calculated, usually as vein length per centimetre squared, but this can be a time‐consuming procedure. In this paper we propose a new rapid method to estimate venation density in a conical sector of Glossopteris leaf lamina using an accurate linear model whose predictors are three linear venation densities, measured as veins per centimetre. In addition to substantially reducing the data collection time, it is less biased and more reproducible than methods applied previously with this leaf type. Using this more robust method, preliminary results significantly distinguish the venation densities of leaves produced in wet and drier ecosystems, matching a pattern similar to modern plants. This is the first survey using a large sample size to reveal that environmental stress controlled the vein architecture of Palaeozoic plants, in a manner similar to plants in modern ecosystems.
The presented tool is a fully virtualized videoconferencing MCU (Multipoint Control Unit) system using the standard SIP (Session Initiation Protocol). The proposed tool works in the cloud in a scalable way, with low deployment and maintenance costs. In addition, the proposed tool is more than an MCU, functioning as a universal framework for media forwarding.
The purpose of this paper is to present advances in the Mconf web conferencing system to support transparent interoperability with room videoconferencing equipment (known as endpoints), Multipresence system, and Phone@RNP. The system can behave as SFU (Switching Forwarding Unit) or MCU (Multipoint Control Unit), making decisions about the best signal to send to each destination. The following main benefits can be cited: 1) Improving user interaction in the use of such systems, so that it simply enters the portal “Video Collaboration Service”, and the system make the necessary adaptations to obtain the best user experience; 2) Have a single MCU + SFU service, savings resources, as it concentrates programmers on the same code.
This paper presents the final results of the development of an MCU module that can be integrated with the Mconf web conferencing service. The development took over three years: two to develop the MCU module in software and one to refine and integrate into the Mconf code. This article presents the main characteristics developed to obtain a viable product. Among them, we can mention the integration of architecture, audio and video web / MCU, document sharing, BFCP protocol, moderation interface, recording and registrar SIP. The paper also presents evidences of this successful integration, as well as load testing on the developed system.
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