Search Results - (Author, Cooperation:Z. Islam)

2018-05-12

American Physical Society (APS)

0031-9007

1079-7114

Physics

Condensed Matter: Electronic Properties, etc.

2018-09-06

American Physical Society (APS)

1098-0121

1095-3795

Physics

Superfluidity and superconductivity

2015-11-07

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2018-07-05

Royal Society

2054-5703

Natural Sciences in General

organic chemistry, computational chemistry

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract Extensive tables of the values ofH-functionsH 0(z, ω) andH 1 0 (z, ω) appropriate for the problems of radiative transfer in multiplying media characterized by ω〉1, have been constructed correctly to the sixth decimal place for values of ω in the range 1.05–10. This accuracy has been attained with the aid of a 32-point Gaussian quadrature.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract In this note we derive an exact solution of transfer equation in a plane-parallel semiinfinite atmosphere with albedo ω〉1, by the method of Laplace transform and Wiener-Hopf technique. The emergent intensityI(0, μ) is obtained in terms of theH 0-functionH 0(μ) (Das Gupta, 1978) for which some good approximations are given. Intensity at any depth is also obtained.I(0, μ)/I(0, 0) is plotted in graphs against μ∈[0,1], and shows a maximum which drops and shifts towards the origin as ω increases.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Electronic Resource

1572-9745

deepwater rice ; pest management ; stem borers ; weeds

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract Deepwater rice has a distinctive pest complex due to prolonged deep flooding, extended growth duration and a complex environment. Flooding smothers weeds, prevents population buildups of some pests and diseases, and stimulates new growth which may compensate for early damage. Major pests are adapted to these aquatic conditions and exploit the succulent growth and mild weather extremes of this period. In Asia, yellow stem borer causes widespread damage by producing a loss of bearing stems, and lighter or empty panicles. No appropriate measures are known and control of this major pest is a daunting challenge. Stem nematode severely damages rice in several areas but varietal resistance is effective. Rats and hispa beetle are also injurious and many lesser pests are known. In West Africa's smaller Deepwater rice area, stem borers, leafeaters, birds and rats are damaging but their effect on yield is obscure. Farmers commonly employ cultural control methods, and insecticides are used in some areas but diseases are not treated. Pesticide use is restricted by application difficulties, contamination concerns and the low value of the crop. In Asia and Africa wild rices, grasses and sedges compete fiercely with rice before flooding; herbicides are not generally used but many farmers hand weed though the extent of yield loss is poorly understood. Pest management research in deepwater rice is difficult because of the nature of the agroecosystem. Most research has been carried out in Asia but the volume has seriously declined over the last decade.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract The transfer equation for the case of grey scattering according to Rayleigh's phase function in a semi-infinite axially symmetric atmosphere is considered. The emergent intensity and the intensity at any optical depth have been determined by the Laplace Transform and Wiener-Hopf Technique.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract Das Gupta represented theH-functions of transport problems for the albedo ω∈[0, 1] in the formH(z)=R(z)−S(z) (see Das Gupta, 1977) whereR(z) is a rational function ofz andS(z) is regular on [−1, 0] c . In this paper we have representedS(z) through a Fredholm integral equation of the second kind with a symmetric real kernelL(y, z) as $$S(z) = f(z) - \int_0^1 {L(y,{\text{ }}z)S(y){\text{ d}}y} $$ . The problem is then solved as an eigenvalue problem. The kernel is converted into a degenerate kernel through finite Taylor's expansion and the integral equation forS(z) takes the form: $$S(z) = f(z) - \sum\nolimits_{i - 1}^N {{\text{ }}\chi _i \int_0^1 {F_i (z)F_i (y)S(y){\text{ d}}y} } $$ (which is solved by the usual procedure) where χ r 's are the discrete eigenvalues andF r 's the corresponding eigenfunctions of the real symmetric kernelL(y, z).

Electronic Resource

1573-8248

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Résumé Les études faites de 1977 à 1980 dans les rizières inondées du Bangladesh montrent que 61 à 89% des pontes du foreur jaune du riz,Scirpophaga incertulas (Walker) sont attaquées par des hyménoptères parasites. Le parasitisme des œufs s'accroît de 43–48% aux générations 2 à 4 (mai à août) jusqu'à 64–88% aux générations 5 et 6 (septembre à novembre). Ce parasitisme a été plus faible pour les générations 4 et 5 en 1979, à cause des densités moins élevées en hôtes, et en 1980 probablement en raison d'une mise en eau très tardive. Telenomus rowani (Gahan), actif toute l'année, parasite 64% des œufs dans les pontes attaquées, de sorte que 32% des larves survivent par ponte.Tetrastichus schoenobii Ferrière, qui se manifeste le premier pour les densités moyennes en hôte, augmente rapidement en nombre et attaque la moitié des pontes des générations 5 et 6. Plus de 98% des œufs dans les pontes attaquées sont parasitées, laissant seulement 1,6 larve survivante par ponte. En 1979, son activité fut retardée de 10 semaines et moins de pontes furent parasitées à cause des densités moindres en hôtes.Trichogramma japonicum Ashmead etTelenomus sp. (parasite nouveau) furent moins importants. Le parasitisme multiple des pontes passe de 7% à la 2ème génération à 28% à la 5ème génération. Ces parasites d'œufs réduisent nettement les populations deS. incertulas et, de ce fait, augmentent vraisemblablement les rendements en riz.

Abstract Studies on deepwater rice in Bangladesh from 1977 to 1980 showed that 61–89% of the egg masses of the yellow rice borer,Scirpophaga incertulas (Walker), were attacked by hymenopterous parasites. Egg parasitism increased from 43–48% in broods 2–4 (May–August) to 64–88% in broods 5–6 (September–November). Parasitism was reduced in broods 4 and 5 in 1979 (because of lower host densities) and in 1980 (possibly due to extreme late flooding). Telenomus rowani (Gahan), active throughout the year, parasitized 64% of the eggs in the masses it attacked, 32 larvae/mass surviving.Tetrastichus schoenobii Ferrière first appearing at medium host densities, increased rapidly to attack half of the brood 5 and 6 masses. More than 98% of the eggs in the attacked masses were parasitized, leaving only 1.6 surviving larvae/mass. In 1979 its appearance was delayed by 10 weeks and fewer masses were parasitized due to lower host densities.Trichogramma japonicum Ashmead andTelenomus sp. (a new record) were less important. Multiple parasitism of masses rose from 7% in brood 2 to 28% in brood 5. Egg parasites clearly reduce the numbers ofS. incertulas, a major pest, and thus probably improve the yields of deepwater rice.

Electronic Resource