Determination of neutron flux distribution by using ANISN, a one-dimensional discrete S sub n ordinates transport code with anisotropic scattering

The purpose of this project was to use a one-dimensional discrete coordinates transport code called ANISN in order to determine the energy-angle-spatial distribution of neutrons in a 6-feet cube rock box which houses a D-T neutron generator at its center. The project was two-fold. The first phase of the project involved adaptation of the ANISN code written for an IBM 360/75/91 computer to the UNIVAC system at JSC. The second phase of the project was to use the code with proper geometry, source function and rock material composition in order to determine the neutron flux distribution around the rock box when a 14.1 MeV neutron generator placed at its center is activated

Development and stability of gyrotactic plumes in bioconvection

Using the continuum model of Pedley, Hill and Kessler (1988) for bioconvection in a suspension of swimming, gyrotactic micro-organisms, we investigate the existence and stability of a two-dimensional plume in tall, narrow chambers with stress-free sidewalls. The system is governed by the Navier–Stokes equations for an incompressible fluid coupled with a micro-organism conservation equation. These equations are solved numerically using a conservative finite-difference scheme. In sufficiently deep chambers, the plume is always unstable to both varicose and meandering modes. A linear stability analysis for an infinitely long plume predicts the growth rates of these instabilities, explains the mechanisms, and is in good agreement with the numerical results

Taylor dispersion of gyrotactic swimming micro-organisms in a linear flow

The theory of generalized Taylor dispersion for suspensions of Brownian particles is developed to study the dispersion of gyrotactic swimming micro-organisms in a linear shear flow. Such creatures are bottom-heavy and experience a gravitational torque which acts to right them when they are tipped away from the vertical. They also suffer a net viscous torque in the presence of a local vorticity field. The orientation of the cells is intrinsically random but the balance of the two torques results in a bias toward a preferred swimming direction. The micro-organisms are sufficiently large that Brownian motion is negligible but their random swimming across streamlines results in a mean velocity together with diffusion. As an example, we consider the case of vertical shear flow and calculate the diffusion coefficients for a suspension of the alga <i>Chlamydomonas nivalis</i>. This rational derivation is compared with earlier approximations for the diffusivity

Analytical detection of stationary and dynamic patterns in a prey-predator model with reproductive Allee effect in prey growth

Allee effect in population dynamics has a major impact in suppressing the paradox of enrichment through global bifurcation, and it can generate highly complex dynamics. The influence of the reproductive Allee effect, incorporated in the prey's growth rate of a prey-predator model with Beddington-DeAngelis functional response, is investigated here. Preliminary local and global bifurcations are identified of the temporal model. Existence and non-existence of heterogeneous steady-state solutions of the spatio-temporal system are established for suitable ranges of parameter values. The spatio-temporal model satisfies Turing instability conditions, but numerical investigation reveals that the heterogeneous patterns corresponding to unstable Turing eigen modes acts as a transitory pattern. Inclusion of the reproductive Allee effect in the prey population has a destabilising effect on the coexistence equilibrium. For a range of parameter values, various branches of stationary solutions including mode-dependent Turing solutions and localized pattern solutions are identified using numerical bifurcation technique. The model is also capable to produce some complex dynamic patterns such as travelling wave, moving pulse solution, and spatio-temporal chaos for certain range of parameters and diffusivity along with appropriate choice of initial conditions Judicious choices of parametrization for the Beddington-DeAngelis functional response help us to infer about the resulting patterns for similar prey-predator models with Holling type-II functional response and ratio-dependent functional response

Production of Fe-Si-Mn from leached sea nodule residue

A pilot plant for processing of polymetallic sea nodule on 500 Kg/day scale has been set up by Department of Ocean Development at CRDL, HZL, Udaipur. After recovery of Cu, Ni & Co by NH3/SO2 pressure leaching, the generated residue contains considerable amount of manganese and iron. Attempts on recovery of manganese from this residue has been made at National Metallurgical Laboratory and standard grade Fe-Si-Mn alloy has been produced. Two different routes of smelting were carried out which comprised single stage smelting of residue blended with manganese containing materials and two stage smelting of residue with out any blending. The process is developed at 20 Kg scale and has been tested at 300 Kg scale in pilot plant also. A maximum recovery of Mn in the form of Fe-Si-Mn alloy has been found 68.0%

Vacancy formation energy of simple metals using reliable model and ab initio pseudopotentials

We present a self-consistent calculation of the mono vacancy formation energy for seven simple metals Li, Na, K, Rb, Cs (all bcc), Al (fcc) and Mg (hcp) using both model and ab initio pseudopotential used in earlier unified studies. The local model pseudopotential calculations show small variations with respect to different exchange-correlation functions and the results are in fair agreement with other similar calculations and the available experimental data. The comparisons show that reliable model (pseudo) potential for simple metals can indeed be obtained for explaining a host of properties. Also, considering the importance of third order term in ab initio calculations, the results of our second order calculation appear fairly reasonable and are comparable with other first principle calculations. The perturbation series being an oscillating one, we hope to improve the calculational results using suitable series convergence acceleration method in the next part of our study

Transforming Steel Domain Green through Innovative Waste Management - A Jindal Approach

The paper summarises the various innovative approaches taken at the COREX process based integrated steel plant of M/s Jindal Vijaynagar Steel Limited. The economics of res-ource recyling has also been described

P21^WAF1/CIP1 RNA expression in highly HIV-1 exposed, uninfected individuals

Some individuals remain HIV-1 antibody and PCR negative after repeated exposures to the virus, and are referred to as HIV-exposed seronegatives (HESN). However, the causes of resistance to HIV-1 infection in cases other than those with a homozygous CCR5Δ32 deletion are unclear. We hypothesized that human p21WAF1/CIP1 (a cyclin-dependent kinase inhibitor) could play a role in resistance to HIV-1 infection in HESN, as p21 expression has been associated with suppression of HIV-1 in elite controllers and reported to block HIV-1 integration in cell culture. We measured p21 RNA expression in PBMC from 40 HESN and 40 low exposure HIV-1 seroconverters (LESC) prior to their infection using a real-time PCR assay. Comparing the 20 HESN with the highest exposure risk (median = 111 partners/2.5 years prior to the 20 LESC with the lowest exposure risk (median = 1 partner/2.5 years prior), p21 expression trended higher in HESN in only one of two experiments (P = 0.11 vs. P = 0.80). Additionally, comparison of p21 expression in the top 40 HESN (median = 73 partners/year) and lowest 40 LESC (median = 2 partners/year) showed no difference between the groups (P = 0.84). There was a weak linear trend between risk of infection after exposure and increasing p21 gene expression (R2 = 0.02, P = 0.12), but again only in one experiment. Hence, if p21 expression contributes to the resistance to viral infection in HESN, it likely plays a minor role evident only in those with extremely high levels of exposure to HIV-1

Long-term effects of fertilizer and manure application on soil quality and sustainability of jute-rice-wheat production system in Indo-Gangetic plain

A long-term fertilizer experiment was initiated in 1971 in sandy loam soil (Eutrochrept) of Barrackpore, West Bengal to study the effects of applying organic and inorganic sources of nutrients on yield of jute-rice-wheat system and soil health. The unfertilized soil supported yields of 0.8 t ha-1 of jute fibre, 1.5 t ha-1 of rice grain and 0.7 t ha-1 of wheat grain (average yield of 42 years). Application of 150% recommended NPK through chemical fertilizers produced maximum yields of jute (2.1 t ha-1), rice (3.8 t ha-1) and wheat (2.8 t ha-1). The yields obtained with 150% NPK fertilizers were 5%, 2.7% and 12% higher than that with 100% NPK fertilizers +FYM. Combined application of 100% NPK fertilizers and FYM, however, increased soil organic carbon, available nitrogen, phosphorus and potassium from 5.60 to 8.90 g kg-1, 270 to 316 kg ha-1, 40.7 to 120 kg ha-1 and 139 to 236 kg ha-1 respectively. Maximum DTPA-extractable micronutrients in soil were also observed with 100%NPK fertilizers+FYM. Applying FYM together with NPK fertilizers increased microbial biomass from 221 to 435 mg kg-1 and microbial quotient from 3.95 to 4.89 with concomitant increase in dehydrogenase, phosphatase and fluorescein-diacetate-hydrolyzing activities in the soil. The acid phosphatase activity (139 to 275 ?g PNPg-1 h-1) was much lower than alkaline phosphatase activity  (479 to 616 ?g PNPg-1 h-1). The enzymes assayed showed significant correlation with microbial-C and organic C. Beneficial effects of integrated nutrient management (NPK+FYM) on soil health were reflected on the yields of all the crops