Spatial-temporal evolution of the current filamentation instability

The spatial-temporal evolution of the purely transverse current filamentation instability is analyzed by deriving a single partial differential equation for the instability and obtaining the analytical solutions for the spatially and temporally growing current filament mode. When the beam front always encounters fresh plasma, our analysis shows that the instability grows spatially from the beam front to the back up to a certain critical beam length; then the instability acquires a purely temporal growth. This critical beam length increases linearly with time and in the non-relativistic regime it is proportional to the beam velocity. In the relativistic regime the critical length is inversely proportional to the cube of the beam Lorentz factor $\gamma_{0b}$. Thus, in the ultra-relativistic regime the instability immediately acquires a purely temporal growth all over the beam. The analytical results are in good agreement with multidimensional particle-in-cell simulations performed with OSIRIS. Relevance of current study to recent and future experiments on fireball beams is also addressed

Role of templating agents on the growth morphology of AIPO4

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Integrating Watershed Management for Land Degradation and Improving Agricultural Productivity in Northeast Thailand

Thailand’s northeastern region accounts for one third of the country’s population and land area, but generates only 15 percent of the gross domestic product. Most of the region’s inhabitants have small holding, are low income farmers who face diverse agricultural and resource problems related to extreme environmental variability, an adverse climate, poor soils and limited, often unreliable water resources. Due to these problems the current agricultural productivity and income is very low. The deforestation and other agricultural practices have led to the changes in the hydrologic environment and caused widespread land degradation problems. To tackle these problems several watershed management programs have been implemented by various government departments and organizations. This paper reviews the various watershed development management works in northeast Thailand and discusses their approaches and impact on agricultural productivity and natural resources. The impact of small-scale water resources (SSWR) development program implemented by the Thai Royal Irrigation Department and Ministry of Agriculture and Cooperatives, on the socio-economic conditions of the farmers in NE Thailand was studied. It was found that the farmers in SSWR area earned more income from agriculture, than farmers outside SSWR area. Farm profitability and source of farm cash income of SSWR farmers were closely related to dry season cash crops rather than wet season rice. Area under double cropping was found to be higher in SSWR area than those outside SSWR area. In terms of productivity, profitability and equity the weir type SSWR system was found to be the most appropriate for northeast Thailand. Overall the study indicated that the small scale water resources can play very significant role in increasing the productivity and income of small rainfed farmers in northeast Thailand. The Department of Land Development approach of watershed development and management gives greater emphasis to small farm ponds and control of soil erosion. This program is being implemented on large scale in Thailand. The Kingdom Watershed Management Program for small, medium and large scale watersheds is also discussed. The results from integrated participatory watershed management project implemented jointly by the Department of Agriculture, Land Development Department and Khon Kaen University in close collaboration with International Crops Research Institute for the Semi- Arid Tropics (ICRISAT) are discussed in detail. This project is being carried out at two benchmark sites, viz., Tad Fa in Phuphaman district and Wang Chai in Phuwiang district in northeast region of Thailand. Results shows that with proper land use planning and use of integrated soil, water and nutrient management (SWMM) and crop management options the land degradation can be controlled (soil loss of 5 t/ha/yr in improved system vs soil loss of 37 t/ha/yr in the traditional system). The project interventions significantly increased the water availability and crop yields. Promising watershed management technologies developed at the project sites provide a good framework for increasing productivity and income of farmers on sustained basis, while improving the soil and water resources

A tachyonic scalar field with mutually interacting components

We investigate the tachyonic cosmological potential $V(\phi)$ in two different cases of the quasi-exponential expansion of universe and discuss various forms of interaction between the two components---matter and the cosmological constant--- of the tachyonic scalar field, which leads to the viable solutions of their respective energy densities. The distinction among the interaction forms is shown to appear in the $O_{m}(x)$ diagnostic. Further, the role of the high- and low-redshift observations of the Hubble parameter is discussed to determine the proportionality constants and hence the correct form of matter--cosmological constant interaction.Comment: 14 page

Modeling Web Services by Iterative Reformulation of Functional and Non-Functional Requirements

Abstract. We propose an approach for incremental modeling of composite Web services. The technique takes into consideration both the functional and nonfunctional requirements of the composition. While the functional requirements are described using symbolic transition systems—transition systems augmented with state variables, function invocations, and guards; non-functional requirements are quantified using thresholds. The approach allows users to specify an abstract and possibly incomplete specification of the desired service (goal) that can be realized by selecting and composing a set of pre-existing services. In the event that such a composition is unrealizable, i.e. the composition is not functionally equivalent to the goal or the non-functional requirements are violated, our system provides the user with the causes for the failure, that can be used to appropriately reformulate the functional and/or non-functional requirements of the goal specification.

Generalized Huygens principle with pulsed-beam wavelets

Huygens' principle has a well-known problem with back-propagation due to the spherical nature of the secondary wavelets. We solve this by analytically continuing the surface of integration. If the surface is a sphere of radius $R$, this is done by complexifying $R$ to $R+ia$. The resulting complex sphere is shown to be a real bundle of disks with radius $a$ tangent to the sphere. Huygens' "secondary source points" are thus replaced by disks, and his spherical wavelets by well-focused pulsed beams propagating outward. This solves the back-propagation problem. The extended Huygens principle is a completeness relation for pulsed beams, giving a representation of a general radiation field as a superposition of such beams. Furthermore, it naturally yields a very efficient way to compute radiation fields because all pulsed beams missing a given observer can be ignored. Increasing $a$ sharpens the focus of the pulsed beams, which in turn raises the compression of the representation.Comment: 49 pages, 14 figure

A review on biochar modulated soil condition improvements and nutrient dynamics concerning crop yields: pathways to climate change mitigation and global food security

The beneficial role of biochar on improvement of soil quality, C sequestration, and enhancing crop yield is widely reported. As such we could not find a compiled source of information linking biochar modulated soil condition improvement and soil nutrient availability on crop yields. The present review paper addresses the above issues by compilation of world literatures on biochar and a new dimension is introduced in this review by performing a meta-analysis of published data by using multivariate statistical analysis. Hence this review is a new in its kind and is useful to the broad spectrum of readers. Generally, alkalinity in biochar increases with increase in pyrolysis temperature and majority of the biochar is alkaline in nature except a few which are acidic. The N content in many biochar was reported to be more than 4% as well as less than 0.5%. Poultry litter biochar is a rich in P (3.12%) and K (7.40%), while paper mill sludge biochar is highest in Ca content (31.1%) and swine solids biochar in Zn (49810 mg kg-1), and Fe (74800 mg kg-1) contents. The effect of biochar on enhancing soil pH was highest in Alfisol, Ferrosol and Acrisol. Soil application of biochar could on an average increase (78%), decrease (16%), or show no effect on crop yields under different soil types. Biochar produced at a lower pyrolysis temperature could deliver greater soil nutrient availabilities than that prepared at higher temperature. Principal component analysis (PCA) of available data shows an inverse relationship between pyrolysis temperature and soil pH, and biochar application rate and soil cation exchange capacity.The PCA also suggests that the original soil properties and application rate strongly control crop yield stimulations via biochar amendments. Finally, biochar application shows net soil C gains while also serving for increased plant biomass production that strongly recommends biochar as a useful soil amendment. Therefore, the application of biochar to soils emerges as a ‘win-win strategy’ for sustainable waste management, climate change mitigation and food security