The Casiquiare River is a natural channel that connects two of the greatest rivers in the world, the Orinoco and the Amazon in the South American Continent. The aim of this paper is to present a review and synthesis of the hydrological and sedimentological knowledge of the Casiquiare River, including the first hydro-sedimentary balance of the Casiquiare fluvial system conducted at the bifurcation and at the mouth on September 9-12, 2000, during the expedition ‘Humboldt-Amazonia 2000’. Bathymetric, flow discharge and physico-chemical measurements were made at the inlet and at the outlet of the Casiquiare Channel. The main conclusions of this study indicate that Casiquiare is taking a significant proportion of flow (20 to 30%) from the Upper Orinoco basin to the Amazon basin. Throughout its 356 km-course, this chameleon channel undergoes significant morphological, hydrological and bio-geochemical variations between the inlet and the outlet, whose most visible witnesses are the increase in its width (3 to 4 times), flow (7 to 9 times) and its change in water color (white to black water), under the influence of tributaries coming from vast forest plains.

(1) Background: Foot strike pattern and cadence are two important variables that are related to sport performance and injury risks; the objective of this study is to analyse the foot strike pattern and cadence of the male elite athlete that participated in the Tokyo Olympic Games marathon. (2) Methods: Two independent researchers analysed the foot strike pattern of the first 51 participants in the 5km, and the cadence of the finalists in three different segments of the race. Descriptive statistics were presented for the main variables of this study. A repeated measures ANOVA was used to study the differences in cadence between different sections of the race (p<0.05). (3) Results: Average of the cadence of the eight finalists was 185.5 steps per minute (SD ± 5.1). No differences between sections of the race were found. The more most common foot strike pattern was midfoot strike pattern, followed by rearfoot strike pattern, and forefoot strike pattern. The results of cadence are in line with previous studies that analysed elite athletes, with the values being higher than other research involving recreational runners. (4) Conclusions: elite marathon runners mostly run with a running non-rearfoot strike pattern and a cadence of over 185 steps per minute.

One of the non-linear phenomena that affect high bandwidth and long reach communication systems is the non-linear phenomenon called four-wave mixing (FWM). Unfortunately, the simulation of such systems aiming to obtain their design parameter limitations require more time as the number of channels increases. In this paper, we propose a new high-performance computational model to obtain optimal design parameters in a multi san Dense Wavelength Division Multiplexing (DWDM) system, limited by FWM and the intrinsic Amplified Spontaneous Emission (ASE) noise of optical amplifiers employed in each segment. The simulation in this work provides a complete optical design characterization and compares the efficiency and speed improvement of the proposed parallelization model versus a previous sequential model. Additionally, an analysis of the computational complexity of parallel model is presented, where two parallel implementations are used. First, Open Multi−Processing (OpenMP), based on the use of a central, multi-core processing unit is used and secondly the Compute Unified Device Arquitecture (CUDA), which is based on the use of graphics processing unit. Results show that parallelism improves to up to 40 times the performance of the simulation when nested parallelization with CUDA is used, over de sequential method and up to 6 times compared with the implementation with OpenMP using 12 processors. Within our parallel implementation, it is possible to simulate with an increased number of channels, that was unpractical in the sequential simulation.