The cosmological kibble mechanism in the laboratory: string formation in liquid crystals     

Bowick MJ  Chandar L  Schiff EA  Srivastava AM 《Science (New York, N.Y.)》1994,263(5149):943-945

The production of strings (disclination lines and loops) has been observed by means of the Kibble mechanism of domain (bubble) formation in the isotropic-nematic phase transition of the uniaxial nematic liquid crystal 4-cyano-4'-n-pentylbiphenyl. The number of strings formed per bubble is about 0.6. This value is in reasonable agreement with a numerical simulation of the experiment in which the Kibble mechanism is used for the order parameter space of a uniaxial nematic liquid crystal.  相似文献   

All-polymer field-effect transistor realized by printing techniques     

Garnier F  Hajlaoui R  Yassar A  Srivastava P 《Science (New York, N.Y.)》1994,265(5179):1684-1686

A field-effect transistor has been fabricated from polymer materials by printing techniques. The device characteristics, which show high current output, are insensitive to mechanical treatments such as bending or twisting. This all-organic flexible device, realized with mild techniques, opens the way for large-area, low-cost plastic electronics.  相似文献   

The evaluation of supply parameter,a new index of zinc availability in Mollisols     

P. C. Srivastava  M. S. Gangwar 《植物养料与土壤学杂志》1989,152(1):33-37

A new zinc supply parameter taking into account the intensity, quantity and buffering capacity and also the relative competitive influence of Cu²⁺, Fe²⁺, Mn²⁺ on the availability of Zn²⁺ has been tested. The proposed parameter correlated significantly and positively to Bray's per cent yield and zinc concentration in some parts of rice plant. The critical limit of soil zinc, in terms of this parameter at 15° and 30°C for rice, were 0.51 and 0.97 respectively. The required zinc addition to the deficient soil was also calculated on the basis of the values of this parameter at 30°C.  相似文献   

Identification and Characterization of Slow Rusting Components in Pea (Pisum sativum L.)     

R. Chand  C. P. Srivastava  B. D. Singh  S. B. Sarode 《Genetic Resources and Crop Evolution》2006,53(2):219-224

Three hundred and forty five accessions of pea of diverse origin, height, leaf types and disease reaction were screened for rust disease severity and area under disease progress curve (AUDPC). The frequency of slow rusting types in the tall, dwarf, early and late groups appeared comparable. Of the 345 accessions, forty-four genotypes were evaluated for disease intensity, which was converted into AUDPC, number of pustules/leaf and pustule size. Wide range of variation was found for these traits. The slow rusting attribute of 16 genotypes was further confirmed by testing these under unprotected (inoculated) and protected (fungicidal spray) conditions for two successive years for disease intensity by assessing the AUDPC, seed yield/plot, and 100-seed weight. The fast rusting genotypes exhibited lower AUDPC, accompanied with increased seed yield and seed weight when grown under the protected condition, as compared to those raised under the unprotected condition. The genotypes Pant P 11, FC 1, HUDP 16, JPBB 3 and HUP 14 appeared as slow rusting genotypes.  相似文献   

Characterization of different cytoplasmic male sterility systems in Indian mustard (Brassica juncea L. Czern & Coss)     

K. H. Singh    K. K. Srivastava 《Plant Breeding》2006,125(1):72-76

Six cytoplasmic male sterility (CMS) systems, viz. moricandia, ogura, oxyrrhina, siifolia, tournefortii and trachystoma of Indian mustard (Brassica juncea L.) were characterized for agronomic and floral characteristics. Introgression of alien cytoplasm caused alterations in different floral traits in ogura, siifolia, tournefortii and trachystoma CMS systems. Varied response to different genetic backgrounds of CMS lines indicated the presence of cytoplasmic–nuclear interaction in alteration of floral traits. On the basis of floral characteristics, CMS systems could be grouped into distinct classes. Siifolia, tournefortii and trachystoma CMS lines had narrow petals, while moricandia, ogura and oxyrrhina had wider petals, which were distinguishable on the basis of visual observations. The ratio between length and width of petals were >2.0 in wide petal group but <2.0 in narrow petal group. Further, the relative position of anther and stigma, which was estimated as the ratio between stamen and style length could differentiate the CMS systems. Stamens were longer than styles in oxyrrhina, equal in moricandia and shorter in ogura, siifolia, tournefortii and trachystoma male sterile lines. Non‐viable pollen grains were present in moricandia and oxyrrhina systems, but absent in other systems. In tournefortii and trachystoma, few flowers showed petaloid corolla. All male sterile lines, except trachystoma, which showed crooked siliqua formation were at par with their respective maintainers for flower initiation, plant height, primary branches, seeds per siliqua, seed yield, harvest index, oil and protein content. In general, flower senescence and maturity occurred earlier in male sterile lines than in their respective maintainer lines.  相似文献   

Genetic diversity in common carp stocks assayed by random-amplified polymorphic DNA markers     

Yaraguntappa Basavaraju  Doddanajappa Theertha Prasad  Kumuda Rani  Shankarnyarayana Pradeep Kumar  Umesha Dhakya Naika  Shrinivas Jahageerdar  Prem Prakash Srivastava  David J. Penman  & Graham C Mair 《Aquaculture Research》2007,38(2):147-155

The common carp (Cyprinus carpio L.) is one of the major aquaculture species, contributing nearly 35% to the inland fish production in Karnataka, India. Stocks collected from Hungary (2), Indonesia and Vietnam were assessed alongside two local stocks in a series of culture performance trials with the objective of setting up a base population for developing a breeding programme. The present study deals with the genetic divergence and polymorphism in these six stocks using random‐amplified polymorphic DNA (RAPD) markers. A total of 180 decamer random primers were screened for polymerase chain reaction (PCR) amplification (OPA 1‐20, OPB1‐20, OPC1‐20, OPD1‐20, OPE1‐20, OPF1‐20, OPG1‐20, OPP1‐20 and OPM1‐20). Eight primers were selected for analysis of common carp genotypes (OPA‐7, OPA‐20, OPB‐17, OPF‐10, OP F‐9, OPG‐4, OPG‐9 and OPP‐16). Out of 492 bands recorded, 57.1% were polymorphic. Stepwise regression analysis was carried out to find best combination markers affecting body weight (P<0.001). The results demonstrate major differences in the genetic structures between different stocks. Dendrogram data showed grouping of individuals according to stocks and corresponding data variables revealed the per cent homology within the stock and also found markers correlating to the body weight.  相似文献   

Forage production and nitrogen nutrition in three grasses under coconut tree shades in the humid-tropics     

C.?B.?PandeyEmail author  S.?K.?Verma  J.?C.?Dagar  R.?C.?Srivastava 《Agroforestry Systems》2011,83(1):1-12

Reduction in forage production (FP) under trees in the humid tropics is well known, but information on how different levels of nitrogen (N) fertilizer influence FP under trees is meager. The present study reports effects of four N fertilizer levels (0, 60, 80 and 120 kg ha⁻¹ N) on net soil N mineralization rate (NMR) and soil moisture (SM), FP, shoot biomass/root biomass ratio (SB/RB), N concentration in SB, N uptake and nitrogen use efficiency (NUE) of three grasses [guinea (Panicum maximum Jacq.), para (Brachiaria mutica (Forssk) Stapf) and hybrid-napier (Pennisetum purpureum Schumach.)] under three canopy positions [under canopy (UC, representing high shade), between canopy (BC, representing low shade) and open] of coconut trees (Cocos nucifera L.) in a coconut based silvopastoral system in the humid tropical climate of South Andaman Island of India. The study was performed for two annual cycles (2005–2006 and 2006–2007). The hypotheses tested were: (1) FP would decline under tree shades, both in N fertilized as well as no N fertilized conditions, when SM was not growth limiting in the open. However, amount of decline in the FP would depend on grass species and intensity of shades i.e., higher was the shade greater would be the decline; (2) N fertilizer would increase FP under tree shades, but the increase depended on grass species, intensity of shades and amount of N applied. Amount of N applied, however, would not annul the shades effects when SM was not growth limiting in the open. The study revealed that the tree reduced light 59% under UC and 32% under BC positions, but the N fertilizer levels increased NMR by 11–51% under UC and 3–44% under BC positions compared to the open. SM did not differ across the canopy positions. Under all situations, FP of all grasses declined under UC (47–78%) and BC (18–32%) positions compared to the open; the decline was greater in Hybrid-napier than Guinea and Para grasses. Forage production of all grasses increased with N fertilizer increments under all canopy positions reaching 32 t ha⁻¹ dry matters for hybrid-napier at 120 kg ha⁻¹ N in the open. Both guinea and para grasses outyielded hybrid-napier grass under UC but not under BC or in the open. N concentration in the forage (SB) also increased as N fertilizer level increased. These observations support our hypotheses and suggest that forage production under coconut palms can be increased by the application of N fertilizer with both guinea and para grasses being more productive than hybrid-napier grass under the high shade. Where light conditions are better, hybrid-napier would produce more forage than the other species.  相似文献   

Litterfall,decomposition, and nitrogen release in two age groups of trees in Casuarina equisetifolia plantations in the dry tropical Vindhyan plateau,India     

Alok K. Srivastava  R. S. Ambasht 《Biology and Fertility of Soils》1996,21(4):277-283

Litterfall, decomposition, and N release in 5-year-old and 8-year-old plantations of Casuarina equisetifolia (Forst.) in the dry tropical region of the Vindhyan plateau were studied during 1989–1990. Maximum litterfall occurred in May. The total litterfall ranged from 7.2 to 9.9t ha^-1 year^-1 in the 5-year-old stand and from 11.3 to 12.7t ha^-1 year^-1 in the 8-year-old stand over the 2-year period. Photosynthetic branchlets contributed 87–95% to the total litter. The relative decomposition rates of litter components of the ash-free mass were highest in the rainy months (4.7 to 9.9mg g^-1 day^-1) followed by winter (2.8 to 3.6 mg g^-1 day^-1) and lowest in the summer months (1.7 to 3.0 mg g^-1 day^-1). Similar patterns were observed for N release. The annual decay constant was highest for cone litter and lowest for photosynthetic branchlets. During decomposition, the photosynthetic branchlets showed N immobilization in November and April, the twig litter in March, and the roots in January and February. N release per unit area (g m^-2) was maximum from the photosynthetic branchlets (5.3–6.3) followed by cones (4.4) > roots (3.4) > twigs (2.6–3.2). The combination of the litter C:N ratio, moisture, and temperature with the relative decomposition rate in a multiple regression analysis explained 66–84% of the variability in mass loss and 58–66% of the variability in N release.  相似文献   

Influence of earthworm culture on fertilization potential and biological activities of vermicomposts prepared from different plant wastes     

Pankaj Kumar Srivastava  Poonam C. Singh  Manjul Gupta  Arpita Sinha  Aradhana Vaish  Ashish Shukla  Nandita Singh  Sri Krishna Tewari 《植物养料与土壤学杂志》2011,174(3):420-429

The present investigation was aimed to analyze influence of earthworm culture on nutritive status, microbial population, and enzymatic activities of composts prepared by utilizing different plant wastes. Vermicomposts were prepared from different types of leaves litter of horticulture and forest plant species by modified vermicomposting process at a farm unit. Initial thermophilic decomposition of waste load using cow‐dung slurry was done in the separate beds. The culture of Eisenia fetida was used for vermicomposting in specially designed vermibeds at the farm unit. The physico‐chemical characteristics, enzyme activities (oxido‐reductases and hydrolases), and microbial population (bacteria, fungi, free‐living nitrogen‐fixing bacteria, actinomycetes, Bacillus, Pseudomonas, phosphate‐solubilizing bacteria and fungi) of vermicomposts were found significantly higher (p < 0.05) than those of control (without earthworm inoculum). The study quantified significant contributions of earthworm culture to physico‐chemical, enzymatic, and microbiological properties of vermicompost and confirmed superior fertilization potential of vermicompost for organic farming. The agronomic utility of vermicompost was assessed on yellow mustard plant in a pot experiment. Pot soil was amended with different ratios (5%, 10%, 20%) of vermicompost and normal compost (without earthworm inoculum). Effects of these amendments on the growth of Brassica comprestis L. were studied. The significant differences (p < 0.05) in the growth of plant were observed among vermicompost‐, compost‐amended soil, and control. Vermicompost increased the root and shoot lengths, numbers of branches and leaves per plant, fresh and dry weights per plant, numbers of pods and flowers, and biochemical properties of plant leaf significantly, especially in 20% amendment. These results proved better fertilization potential of vermicompost over non‐earthworm‐inoculated compost.  相似文献   

RADIOGRAPHIC DIAGNOSIS     

Ronald  McKnight  DVM  Kunwar K.  Srivastava  DVM  PhD 《Veterinary radiology & ultrasound》1995,36(2):111-111

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