Charged-particle orbits near a magnetic null point

An approximate analytical expression is obtained for the orbits of a charged particle moving in a cusp magnetic field. The particle orbits pass close to or through a region of zero magnetic field before being reflected in regions where the magnetic field is strong. Comparison with numerically evaluated orbits shows that the analytical formula is surprisingly good and captures all the main features of the particle motion. A map describing the long-time behaviour of such orbits is obtained

Assessment of spatio-temporal variations in water quality of Bandon Bay, Thailand

1000-1010Multivariate statistical techniques were used to analyse a ten-year water quality dataset. Monthly water samples were collected from 15 river mouths during 2002-2011 and analysed for spatio-temporal variation. The results indicated that water quality at Bandon Bay varied spatially and temporally during the past ten years. Four pollution factors were identified: (1) nutrient, (2) organic matter, (3) salinity and buffering and (4) erosion factors. Discriminant analysis on spatial variables identified only four parameters - i.e. water depth, alkalinity, salinity, and temperature - to discriminate between 15 river mouths. Salinity was the only parameter that discriminated between seasons

Applying a landscape mosaics technique to detect tropical cyclone impacts on coral reef community

1017-1024This study demonstrated that with an off-the-shelf underwater camera and the Adobe Photoshop software, end-users in developing countries with limited resources could use the video mosaics technique for reef monitoring and documenting storm impacts. This video-mosaic method provided a spatially accurate landscape view of the reef benthos. Images from the video-mosaic method revealed that up to 26% of the reef coral at Racha Island disappeared after the storm with 15% increase in sand, pavement and rubble. Most of the coral destroyed by the storm were foliaceous coral - i.e. Montipora sp

Wireless Sensor Network for Ocean Observatory

941-950Present article is a review on wireless sensor technology and application for ocean observation. A variety of tools and sensors are widely used for recording and watching online marine physical parameters such as sea temperature, salinity and pH value. An information system is deployed for surveillance and early warning systems for ecologists. These systems are user-friendly and accessible. All information is useful for ecological and environmental assessment. Data are collected at the study sites with a variety of online real-time sensors at various locations around the world