A new model of gross primary productivity for North American ecosystems based solely on the enhanced vegetation index and land surface temperature from MODIS

Many current models of ecosystem carbon exchange based on remote sensing, such as the MODIS product termed MOD17, still require considerable input from ground based meteorological measurements and look up tables based on vegetation type. Since these data are often not available at the same spatial scale as the remote sensing imagery, they can introduce substantial errors into the carbon exchange estimates. Here we present further development of a gross primary production (GPP) model based entirely on remote sensing data. In contrast to an earlier model based only on the enhanced vegetation index (EVI), this model, termed the Temperature and Greenness (TG) model, also includes the land surface temperature (LST) product from MODIS. In addition to its obvious relationship to vegetation temperature, LST was correlated with vapor pressure deficit and photosynthetically active radiation. Combination of EVI and LST in the model substantially improved the correlation between predicted and measured GPP at 11 eddy correlation flux towers in a wide range of vegetation types across North America. In many cases, the TG model provided substantially better predictions of GPP than did the MODIS GPP product. However, both models resulted in poor predictions for sparse shrub habitats where solar angle effects on remote sensing indices were large. Although it may be possible to improve the MODIS GPP product through improved parameterization, our results suggest that simpler models based entirely on remote sensing can provide equally good predictions of GPP.     

Response of the Sundarbans coastline to sea level rise and decreased sediment flow: A remote sensing assessment

The Sundarbans is the world's largest remaining single block of mangrove forest, covering approximately 1 million ha (~ 10,000 km²) of the Ganges-Brahmaputra delta along the coastal areas of India and Bangladesh. Sea level rise and alteration of water flows of the Himalayan headwaters are among the major disturbances threatening these coastal areas. But very few studies exist on the dynamics or current status of the Sundarbans coastline. We used Landsat images spanning from 1973 to 2010, and an algorithm that we developed, to consistently estimate the spatiotemporal dynamics of erosion and accretion for four different time intervals and the whole study period. Our results show that the direction and extent of erosion and accretion rates varied throughout the different periods. Erosion was the highest in the 1973-1979 interval, with 23.2 km² year⁻¹ of land loss. However, that rate substantially declined in the following periods, reaching a rate of 7-10 km² year⁻¹. Accretion showed a rate of 10 km² year⁻¹ between 1973 and 1989, but substantially declined to ~ 4 km² year⁻¹ between 1989 and 2010. Accretion rate has declined in the recent years but erosion rate has remained relatively high. As a result the delta front has undergone a net erosion of ~ 170 km² of coastal land in the 37 years of our study period. These numbers are significantly higher than the previously reported rates and magnitudes of erosion in this area. The methods and maps developed in this study may be helpful in management planning of this vulnerable coastline.     

Electrospinning of highly aligned and covalently cross‐linked hydrogel microfibers

Smart polyelectrolyte hydrogels are increasingly studied toward the realization of soft microactuators. This study focuses on the fabrication of highly aligned and covalently cross‐linked polyacrylamide hydrogel microfibers by electrospinning technique following two‐stage polymerization. The engineering of the reaction timescale of the precursor, such that the material gels shortly after spinning, is described and the design of the electrospinning setup, to generate highly aligned fibers, is presented. In addition the effect of the operating parameters on the fibers average diameter is investigated. The generated fibers are 15 cm long with average diameter ranging between 100 nm and 1.10 μm. The fibers diameter is controlled by adjusting the thickener type and concentration in the precursor and the electrospinning processing parameters. Thinner fibers are generated at lower thickener molecular weights and concentrations as well at lower flow rate and higher voltage. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41092.     

Trust model for secure group leader-based communications in VANET

Wireless Networks - VANET aims to improve safety for all road users. Vehicles exchange safety messages over wireless communication links which are prone to multiple attacks. To enhance the existing...     

Effect of plasma power on the semiconducting behavior of low-frequency PECVD TiO2 and nitrogen-doped TiO2 anodic thin coatings: photo-electrochemical studies in a single compartment cell for hydrogen generation by solar water splitting

Journal of Applied Electrochemistry - Previously optimized anatase and nitrogen-doped anatase TiO2 coatings have been grown by low-frequency plasma-enhanced chemical vapor deposition (PECVD) on...     

Investigating the mechanism of microbiologically influenced corrosion of carbon steel using X-ray micro-computed tomography

Journal of Materials Science - The mechanism of pitting corrosion of carbon steel by an oilfield microbial consortium was investigated using a combination of X-ray micro-computed tomography...     

Natural Disaster,Mitigation and Sustainability: The Case of Developing Countries

The application of sustainable development principles to natural disaster mitigation in developing countries is examined. Three main and interrelated aspects are considered: land-use planning and policies; shelter design, building materials and construction methods; and institutional organization at local, provincial, national and international levels. These three aspects are illustrated on the basis of experiences of human settlements in specific disaster situations and of housing the poor in developing countries in general. Taking into consideration the scale of the problem and the variety of conditions, the most pressing issues are identified, along with the different remedies and the major areas for policy intervention. However, transferring these ideas into implementation strategies, in which creative combinations of solutions, priorities, timeframes and resources are to be identified, will depend on a particular disaster situation and obviously cannot be carried out without detailed examination of the circumstances. Adjustments and changes are proposed to the ways in which human settlements are shaped, grown and managed in order to ensure harmonious interactions between natural and human systems, so that vulnerability to natural disasters is minimized.     

Rectovaginal septum adenomyotic nodules: a series of 500 cases

PURPOSE: Selective mesenteric angiography is an expensive, invasive, diagnostic, and therapeutic tool for lower gastrointestinal hemorrhage. Some institutions have required a positive nuclear medicine bleeding scan before angiography. We have attempted to determine if this is a valid screening test for mesenteric angiography. Are there any other factors to predict which patients are actively bleeding and who will benefit from angiography? METHODS: All cases of mesenteric angiography for hemorrhage performed during a 12-year period were reviewed. RESULTS: A total of 131 angiograms were performed during a 12-year period with 45 patients demonstrating active bleeding; 54 patients had a bleeding scan before angiography. A positive bleeding scan did not increase the percentage of positive angiograms. A history of prior gastrointestinal bleeding, transfusions, orthostatic hypotension, or tachycardia were not predictors for a positive angiogram. DISCUSSION: This study could not identify any single useful predictor that will increase the likelihood of obtaining a positive angiogram. Nuclear medicine scans should not be used routinely as a screening test for angiography.     

Formation mechanism of polyaniline self‐assembled needles and urchin‐like structures assisted by magnesium oxide

The polyaniline (PANI) morphological structure is strongly correlated with the preparation procedure, yielding diverse geometries such as nano‐tubes, belts, rods, fibres and particles. In this study, the synthesis of a novel PANI morphology of consisting of hollow needles and urchin‐like structures is presented and its formation mechanism is explained. The polymer was synthesized by chemical oxidative polymerization of aniline in the presence of magnesium oxide as a structural directing agent. The morphological study of the urchin‐like PANI was conducted using scanning electron microscopy and in situ monitoring of needle growth was done using optical microscopy. The structure and functional groups of these novel structures were characterized using Fourier transform infrared spectroscopy. Additionally, the formation mechanism is modelled based on the multi‐layer theory where a core–shell structure exists between the polymer (shell) and the magnesium oxide particles (core). © 2014 Society of Chemical Industry