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3. Antinociceptive Activity of Dalbergia spinosa Roxb. Stem Barks

Author

Subrata Kumar Biswas, Joysree Das, A.C. Das, Sheikh Zahir Raihan, P. Biswas, M.M. Monir, and A. K. Azad Chowdhury

Subjects
Dalbergia, Traditional medicine, Molecular Medicine, Cell Biology, Biology, biology.organism_classification
Published
2012

4. [Untitled]

Author

S. Bhattacharyya, A.C. Das Ghosh, Bhaskar De, and P. Guptaroy

Subjects
Physics, Work (thermodynamics), Particle physics, High energy, Hadron, General Physics and Astronomy, Cosmic ray, Observable, Particle accelerator, law.invention, Nuclear physics, Cross section (physics), law, Ultra-high-energy cosmic ray
Abstract

The total cross-sections in high energy hadronic collisions constitute a crucial physical observable in the areas of both particle physics and cosmic ray physics phenomena. In fact, this acts as the linking bridge between these two fields of persistent studies—both experimental and theoretical. In the present work we aim at providing some global and excellent fits to the latest available data on PP total cross-sections from the viewpoint of two phenomenological models. The fits would then be compared and discussed.

Published
2002

5. Δ++ production in 158 A GeV 208Pb+208Pb interactions at the CERN SPS

Author

M.M. Aggarwal, A. Agnihotri, Z. Ahammed, A.L.S. Angelis, V. Antonenko, V. Arefiev, V. Astakhov, V. Avdeitchikov, T.C. Awes, P.V.K.S. Baba, S.K. Badyal, A. Baldine, L. Barabach, C. Barlag, S. Bathe, B. Batiounia, T. Bernier, K.B. Bhalla, V.S. Bhatia, C. Blume, R. Bock, E.-M. Bohne, Z. Böröcz, D. Bucher, A. Buijs, H. Büsching, L. Carlen, V. Chalyshev, S. Chattopadhyay, R. Cherbatchev, T. Chujo, A. Claussen, A.C. Das, M.P. Decowski, H. Delagrange, V. Djordjadze, P. Donni, I. Doubovik, S. Dutt, M.R. Dutta Majumdar, K. El Chenawi, S. Eliseev, K. Enosawa, P. Foka, S. Fokin, V. Frolov, M.S. Ganti, S. Garpman, O. Gavrishchuk, F.J.M. Geurts, T.K. Ghosh, R. Glasow, S.K. Gupta, B. Guskov, H.Å. Gustafsson, H.H. Gutbrod, R. Higuchi, I. Hrivnacova, M. Ippolitov, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, K. Karpio, S. Kato, S. Kees, B.W. Kolb, I. Kosarev, I. Koutcheryaev, T. Krümpel, A. Kugler, P. Kulinich, M. Kurata, K. Kurita, N. Kuzmin, I. Langbein, A. Lebedev, Y.Y. Lee, H. Löhner, L. Luquin, D.P. Mahapatra, V. Manko, M. Martin, G. Martı́nez, A. Maximov, R. Mehdiyev, G. Mgebrichvili, Y. Miake, D. Mikhalev, Md.F. Mir, G.C. Mishra, Y. Miyamoto, B. Mohanty, D. Morrison, D.S. Mukhopadhyay, V. Myalkovski, H. Naef, B.K. Nandi, S.K. Nayak, T.K. Nayak, S. Neumaier, A. Nianine, V. Nikitine, S. Nikolaev, P. Nilsson, S. Nishimura, P. Nomokonov, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, M. Pachr, A. Parfenov, S. Pavliouk, T. Peitzmann, V. Petracek, F. Plasil, W. Pinganaud, M.L. Purschke, J. Rak, R. Raniwala, S. Raniwala, V.S. Ramamurthy, N.K. Rao, F. Retiere, K. Reygers, G. Roland, L. Rosselet, I. Roufanov, C. Roy, J.M. Rubio, H. Sako, S.S. Sambyal, R. Santo, S. Sato, H. Schlagheck, H.-R. Schmidt, Y. Schutz, G. Shabratova, T.H. Shah, I. Sibiriak, T. Siemiarczuk, D. Silvermyr, B.C. Sinha, N. Slavine, K. Söderström, N. Solomey, S.P. Sørensen, P. Stankus, G. Stefanek, P. Steinberg, E. Stenlund, D. Stüken, M. Sumbera, T. Svensson, M.D. Trivedi, A. Tsvetkov, L. Tykarski, J. Urbahn, E.C. van der Pijll, N. van Eijndhoven, G.J. van Nieuwenhuizen, A. Vinogradov, Y.P. Viyogi, A. Vodopianov, S. Vörös, B. Wysłouch, K. Yagi, Y. Yokota, and G.R. Young

Subjects
Physics, Nuclear physics, Delta, Nuclear and High Energy Physics, Particle physics, Large Hadron Collider, Pion, Invariant mass, Chemical equilibrium, Nuclear Experiment
Abstract

The Delta(++)-resonance production in central 158 A GeV Pb-208 + Pb-208 collisions at the CERN SPS has been studied. The Delta(++) production was estimated from the invariant mass spectrum of p pi(+)-pairs by subtracting a mixed event background. The measured Delta(++) abundance is compared with the results from other experiments at lower energies, and with a model calculation assuming thermal and chemical equilibrium. (C) 2000 Elsevier Science B.V. All rights reserved.

Published
2000

6. Soil application of insecticides influences microorganisms and plant nutrients

Author

A.C. Das and Debargha Mukherjee

Subjects
Fenvalerate, education.field_of_study, Phorate, Ecology, biology, Population, Soil Science, Soil classification, Pesticide, biology.organism_classification, Agricultural and Biological Sciences (miscellaneous), Toxicology, chemistry.chemical_compound, chemistry, Agronomy, Rhizopus, Trichoderma, education, Carbofuran
Abstract

An experiment was conducted under laboratory conditions to investigate the effect of four insecticides, viz. HCH, phorate, carbofuran and fenvalerate at their field application rates (7.5, 1.5, 1.0 and 0.35 kg a.i. ha 1 , respectively), on the growth and development of bacteria, actinomycetes and fungi as well as their role in the transformations and availability of some plant nutrients in laterite soil ( Typic Orchragualf). All the insecticides in general, and HCH and phorate in particular, significantly increased the population of microorganisms in soil. The most predominant genera of microorganisms, such as Bacillus, Micrococcusand Aspergillus were not affected by most of the insecticides. However, some of the insecticides stimulated the growth and development of Bacillus, Proteus, Corynebacterium, Streptomyces, Fusarium, Trichoderma and Rhizopus .O n the other hand, some insecticide exerted deleterious effect on the proportions of Pseudomonas, Staphylococcus, Nocardia, Micromonospora, Aspergillus and Rhizopus. Incorporation of insecticides also significantly stimulated the mineralization and availability of organic C, N and P in soil. Among the tested substances, the stimulations were more pronounced with HCH followed by phorate and fenvalerate. ©2000 Elsevier Science B.V. All rights reserved.

Published
2000

7. Field aligned current and particle acceleration in the near-Io plasma torus

Author

Wing-Huen Ip and A.C. Das

Subjects
Physics, Particle acceleration, Space and Planetary Science, Physics::Space Physics, Astronomy and Astrophysics, Torus, Plasma, Atomic physics, Current (fluid), Ionosphere, Shear flow, Current density, Jovian
Abstract

The magnetospheric interaction of Io is characterized by a strong field-aligned current connecting Io to the Jovian ionosphere. It is shown here that the mass-loading effect near Io could be responsible for an enhanced current density in the shear flow region which produce a high level of kinetic Alfven waves for particle acceleration.

Published
2000

8. Elliptic emission of K+ and π+ in 158 A·GeV Pb + Pb collisions

Author

M.M. Aggarwal, A. Agnihotri, Z. Ahammed, A.L.S. Angelis, V. Antonenko, V. Arefiev, V. Astakhov, V. Avdeitchikov, T.C. Awes, P.V.K.S. Baba, S.K. Badyal, A. Baldine, L. Barabach, C. Barlag, S. Bathe, B. Batiounia, T. Bernier, K.B. Bhalla, V.S. Bhatia, C. Blume, R. Bock, E.-M. Bohne, Z. Böröcz, D. Bucher, A. Buijs, H. Büsching, L. Carlen, V. Chalyshev, S. Chattopadhyay, R. Cherbatchev, T. Chujo, A. Claussen, A.C. Das, M.P. Decowski, H. Delagrange, V. Djordjadze, P. Donni, I. Doubovik, S. Dutt, M.R. Dutta Majumdar, K. El Chenawi, S. Eliseev, K. Enosawa, P. Foka, S. Fokin, V. Frolov, M.S. Ganti, S. Garpman, O. Gavrishchuk, F.J.M. Geurts, T.K. Ghosh, R. Glasow, S.K. Gupta, B. Guskov, H.Å. Gustafsson, H.H. Gutbrod, R. Higuchi, I. Hrivnacova, M. Ippolitov, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, K. Karpio, S. Kato, S. Kees, B.W. Kolb, I. Kosarev, I. Koutcheryaev, T. Krümpel, A. Kugler, P. Kulinich, M. Kurata, K. Kurita, N. Kuzmin, I. Langbein, A. Lebedev, Y.Y. Lee, H. Löhner, L. Luquin, D.P. Mahapatra, V. Manko, M. Martin, G. Martı́nez, A. Maximov, R. Mehdiyev, G. Mgebrichvili, Y. Miake, D. Mikhalev, Md.F. Mir, G.C. Mishra, Y. Miyamoto, D. Morrison, B. Mohanty, D.S. Mukhopadhyay, V. Myalkovski, H. Naef, B.K. Nandi, S.K. Nayak, T.K. Nayak, S. Neumaier, A. Nianine, V. Nikitine, S. Nikolaev, P. Nilsson, S. Nishimura, P. Nomokonov, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, M. Pachr, A. Parfenov, S. Pavliouk, T. Peitzmann, V. Petracek, F. Plasil, W. Pinganaud, M.L. Purschke, B. Raeven, J. Rak, R. Raniwala, S. Raniwala, V.S. Ramamurthy, N.K. Rao, F. Retiere, K. Reygers, G. Roland, L. Rosselet, I. Roufanov, C. Roy, J.M. Rubio, H. Sako, S.S. Sambyal, R. Santo, S. Sato, H. Schlagheck, H.-R. Schmidt, Y. Schutz, G. Shabratova, T.H. Shah, I. Sibiriak, T. Siemiarczuk, D. Silvermyr, B.C. Sinha, N. Slavine, K. Söderström, N. Solomey, S.P. Sørensen, P. Stankus, G. Stefanek, P. Steinberg, E. Stenlund, D. Stüken, M. Sumbera, T. Svensson, M.D. Trivedi, A. Tsvetkov, L. Tykarski, J. Urbahn, E.C. v.d. Pijll, N. v. Eijndhoven, G.J. v. Nieuwenhuizen, A. Vinogradov, Y.P. Viyogi, A. Vodopianov, S. Vörös, B. Wysłouch, K. Yagi, Y. Yokota, and G.R. Young

Subjects
Nuclear physics, Azimuth, Physics, Nuclear and High Energy Physics, Meson, Angular correlation, Plane (geometry), Astrophysics::High Energy Astrophysical Phenomena, Anisotropic flow, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment
Abstract

An event-by-event analysis of the azimuthal angular correlation with respect to the reaction plane has been carried out for K+ and pi(+) emission near mid-rapidity in 158 A . GeV Pb + Pb collisions. In semi-central collisions, K+ mesons are found to be preferentially emitted out of the reaction plane, while pi(+) mesons are emitted in the reaction plane. The results suggest that the kaon emission is influenced by in-medium potential effects in addition to collective flow effects. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

Published
1999

9. Direct photon production in high-energy heavy-ion collisions

Author

V. Manko, M.M. Aggarwal, A. Agnihotri, Z. Ahammed, A.L.S. Angelis, V. Antonenko, V. Arefiev, V. Astakhov, V. Avdeitchikov, T.C. Awes, P.V.K.S. Baba, S.K. Badyal, A. Baldine, L. Barabach, C. Barlag, S. Bathe, B. Batiounia, T. Bernier, K.B. Bhalla, V.S. Bhatia, C. Blume, R. Bock, E.-M. Bohne, Z. Böröcz, D. Bucher, A. Buijs, H. Büsching, L. Carlen, V. Chalyshev, S. Chattopadhyay, R. Cherbatchev, T. Chujo, A. Claussen, A.C. Das, M.P. Decowski, V. Djordjadze, P. Donni, I. Doubovik, S. Dutt, M.R. Dutta Majumdar, K. El Chenawi, S. Eliseev, K. Enosawa, P. Foka, S. Fokin, V. Frolov, M.S. Ganti, S. Garpman, O. Gavrishchuk, F.J.M. Geurts, T.K. Ghosh, R. Glasow, S.K. Gupta, B. Guskov, H.A Gustafsson, H.H. Gutbrod, R. Higuchi, I. Hrivnacova, M. Ippolitov, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, K. Karpio, S. Kato, S. Kees, H. Kim, B.W. Kolb, I. Kosarev, I. Koutcheryaev, T. Krümpel, A. Kugler, P. Kulinich, M. Kurata, K. Kurita, N. Kuzmin, I. Langbein, A. Lebedev, Y.Y. Lee, H. Löhner, L. Luquin, D.P. Mahapatra, M. Martin, A. Maximov, R. Mehdiyev, G. Mgebrichvili, Y. Miake, D. Mikhalev, Md.F. Mir, G.C. Mishra, Y. Miyamoto, D. Morrison, D.S. Mukhopadhyay, V. Myalkovski, H. Naef, B.K. Nandi, S.K. Nayak, T.K. Nayak, S. Neumaier, A. Nianine, V. Nikitine, S. Nikolaev, P. Nilsson, S. Nishimura, P. Nomokonov, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, M. Pachr, A. Parfenov, S. Pavliouk, T. Peitzmann, V. Petracek, F. Plasil, W. Pinanaud, M.L. Purschke, B. Raeven, J. Rak, R. Raniwala, S. Raniwala, V.S. Ramamurthy, N.K. Rao, F. Retiere, K. Reygers, G. Roland, L. Rosselet, I. Roufanov, C. Roy, J.M. Rubio, H. Sako, S.S. Sambyal, R. Santo, S. Sato, H. Schlagheck, H.-R. Schmidt, G. Shabratova, T.H. Shah, I. Sibiriak, T. Siemiarczuk, D. Silvermyr, B.C. Sinha, N. Slavine, K. Söderström, N. Solomey, S.P. Sørensen, P. Stankus, G. Stefanek, P. Steinberg, E. Stenlund, D. Stüken, M. Sumbera, T. Svensson, M.D. Trivedi, A. Tsvetkov, L. Tykarski, J. Urbahn, E.C.v.d. Pijll, N.v. Eijndhoven, G.J.v. Nieuwenhuizen, A. Vinogradov, Y.P. Viyogi, A. Vodopianov, S. Vörös, B. Wyslouch, K. Yagi, Y. Yokota, and G.R. Young

Subjects
Massless particle, Physics, Nuclear physics, Nuclear reaction, Nuclear and High Energy Physics, Strange matter, Photon, Hadron, Two-photon physics, Elementary particle, Atomic physics, Particle detector
Published
1999

10. Recent results on Pb+Pb collisions at 158 AGeV from the WA98 experiment at CERN

Author

B. Wyslouch, M.M. Aggarwal, A. Agnihotri, Z. Ahammed, A.L.S. Angelis, V. Antonenko, V. Arefiev, V. Astakhov, V. Avdeitchikov, T.C. Awes, P.V.K.S. Baba, S.K. Badyal, A. Baldine, L. Barabach, C. Barlag, S. Bathe, B. Batiounia, T. Bernier, K.B. Bhalla, V.S. Bhatia, C. Blume, R. Bock, E.-M. Bohne, D. Bucher, A. Buijs, E.-J. Buis, H. Büsching, L. Carlen, V. Chalyshev, S. Chattopadhyay, R. Cherbatchev, T. Chujo, A. Claussen, A.C. Das, M.P. Decowski, V. Djordjadze, P. Donni, I. Doubovik, M.R. Dutta Majumdar, K. El Chenawi, S. Eliseev, K. Enosawa, H. Feldmann, P. Foka, S. Fokin, V. Frolov, M.S. Ganti, S. Garpman, O. Gavrishchuk, F.J.M. Geurts, T.K. Ghosh, R. Glasow, S.K. Gupta, B. Guskov, H.A. Gustafsson, H.H. Gutbrod, R. Higuchi, I. Hrivnacova, M. Ippolitov, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, K. Karpio, S. Kato, S. Kees, H. Kim, B.W. Kolb, I. Kosarev, I. Koutcheryaev, A. Kugler, P. Kulinich, V. Kumar, M. Kurata, K. Kurita, N. Kuzmin, I. Langbein, A. Lebedev, Y.Y. Lee, H. Löhner, D.P. Mahapatra, V. Manko, M. Martin, A. Maximov, R. Mehdiyev, G. Mgebrichvili, Y. Miake, D. Mikhalev, G.C. Mishra, Y. Miyamoto, D. Morrison, D.S. Mukhopadhyay, V. Myalkovski, H. Naef, B.K. Nandi, S.K. Nayak, T.K. Nayak, S. Neumaier, A. Nianine, V. Nikitine, S. Nikolaev, P. Nilsson, S. Nishimura, P. Nomokov, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, M. Pachr, A. Parfenov, S. Pavliouk, T. Peitzmann, V. Petracek, F. Plasil, M.L. Purschke, B. Raeven, J. Rak, S. Raniwala, V.S. Ramamurthy, N.K. Rao, F. Retiere, K. Reygers, G. Roland, L. Rosselet, I. Roufanov, J.M. Rubio, S.S. Sambyal, R. Santo, S. Sato, H. Schlagheck, H.-R. Schmidt, G. Shabratova, I. Sibiriak, T. Siemiarczuk, D. Silvermyr, B.C. Sinha, N. Slavine, K. Söderström, N. Solomey, S.P. Sørensen, P. Stankus, G. Stefanek, P. Steinberg, E. Stenlund, D. Stüken, M. Sumbera, T. Svensson, M.D. Trivedi, A. Tsvetkov, C. Twenhöfel, L. Tykarski, J. Urbahn, N.v. Eijndhoven, W.H.v. Heeringen, G.J.v. Nieuwenhuizen, A. Vinogradov, Y.P. Viyogi, A. Vodopianov, S. Vörös, M.A. Vos, K. Yagi, Y. Yokota, and G.R. Young

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Photon, Large Hadron Collider, Spectrometer, Physics::Instrumentation and Detectors, Hadron, Spectral line, Particle identification, Calorimeter, Nuclear physics, Nuclear Experiment, Neutral particle
Abstract

We present recent results obtained with the WA98 experiment at CERN SPS. The experiment consists of large acceptance hadron and photon spectrometers which allow to study many aspects of heavy ion collisions. We use event-by-event measurements of charged and neutral particle multiplicity to establish the limit on the prodution of Disoriented Chiral Condensates. We use the Plastic Ball detector together with a set of tracking chambers to study collective flow. The tracking chambers together with the excellent particle identification allow us to study the production of Δ ++ . The high resolution photon calorimeter array allows us to study inclusive photon and π 0 spectra and search for excess direct photons.

Published
1998

11. Search for disoriented chiral condensates in 158 AGeV Pb+Pb collisions

Author

M.M Aggarwal, A Agnihotri, Z Ahammed, A.L.S Angelis, V Antonenko, V Arefiev, V Astakhov, V Avdeitchikov, T.C Awes, P.V.K.S Baba, S.K Badyal, A Baldine, L Barabach, C Barlag, S Bathe, B Batiounia, T Bernier, K.B Bhalla, V.S Bhatia, C Blume, R Bock, E.-M Bohne, D Bucher, A Buijs, E.-J Buis, H Büsching, L Carlen, V Chalyshev, S Chattopadhyay, R Cherbatchev, T Chujo, A Claussen, A.C Das, M.P Decowski, V Djordjadze, P Donni, I Doubovik, M.R Dutta Majumdar, K El Chenawi, S Eliseev, K Enosawa, P Foka, S Fokin, V Frolov, M.S Ganti, S Garpman, O Gavrishchuk, F.J.M Geurts, T.K Ghosh, R Glasow, S.K Gupta, B Guskov, H.A Gustafsson, H.H Gutbrod, R Higuchi, I Hrivnacova, M Ippolitov, H Kalechofsky, R Kamermans, K.-H Kampert, K Karadjev, K Karpio, S Kato, S Kees, H Kim, B.W Kolb, I Kosarev, I Koutcheryaev, A Kugler, P Kulinich, V Kumar, M Kurata, K Kurita, N Kuzmin, I Langbein, A Lebedev, Y.Y Lee, H Löhner, L Luquin, D.P Mahapatra, V Manko, M Martin, A Maximov, R Mehdiyev, G Mgebrichvili, Y Miake, D Mikhalev, G.C Mishra, Y Miyamoto, D Morrison, D.S Mukhopadhyay, V Myalkovski, H Naef, B.K Nandi, S.K Nayak, T.K Nayak, S Neumaier, A Nianine, V Nikitine, S Nikolaev, S Nishimura, P Nomokonov, J Nystrand, F.E Obenshain, A Oskarsson, I Otterlund, M Pachr, A Parfenov, S Pavliouk, T Peitzmann, V Petracek, F Plasil, M.L Purschke, B Raeven, J Rak, S Raniwala, V.S Ramamurthy, N.K Rao, F Retiere, K Reygers, G Roland, L Rosselet, I Roufanov, C Roy, J.M Rubio, H Sako, S.S Sambyal, R Santo, S Sato, H Schlagheck, H.-R Schmidt, G Shabratova, I Sibiriak, T Siemiarczuk, B.C Sinha, N Slavine, K Söderström, N Solomey, S.P Sørensen, P Stankus, G Stefanek, P Steinberg, E Stenlund, D Stüken, M Sumbera, T Svensson, M.D Trivedi, A Tsvetkov, C Twenhöfel, L Tykarski, J Urbahn, N v. Eijndhoven, W.H v. Heeringen, G.J v. Nieuwenhuizen, A Vinogradov, Y.P Viyogi, A Vodopianov, S Vörös, M.A Vos, B Wysłouch, K Yagi, Y Yokota, G.R Young, and Research unit Nuclear & Hadron Physics

Subjects
Physics, Nuclear and High Energy Physics, Chiral symmetry, Particle physics, SIMPLE (dark matter experiment), Phase transition, Large Hadron Collider, Photon, Hadron, Nuclear Theory, FOS: Physical sciences, Central region, QCD, High Energy Physics - Experiment, ENERGY, High Energy Physics - Experiment (hep-ex), Pion, CERN, PHASE-TRANSITION, Nuclear Experiment, DETECTOR, Particle Physics - Experiment
Abstract

The restoration of chiral symmetry and its subsequent breaking through a phase transition has been predicted to create regions of Disoriented Chiral Condensates (DCC). This phenomenon has been predicted to cause anomalous fluctuations in the relative production of charged and neutral pions in high-energy hadronic and nuclear collisions. The WA98 experiment has been used to measure charged and photon multiplicities in the central region of 158 AGeV Pb+Pb collisions at the CERN SPS. In a sample of 212646 events, no clear DCC signal can be distinguished. Using a simple DCC model, we have set a 90% C.L. upper limit on the maximum DCC production allowed by the data., 20 Pages, LaTeX, uses elsart.cls, 8 eps figures included, submitted to Physics Letters B

Published
1998

12. [Untitled]

Author

D. Mukherjee and A.C. Das

Subjects
Fenvalerate, Sarcina, education.field_of_study, Phorate, Azotobacter, biology, Physiology, Population, Micrococcus, General Medicine, biology.organism_classification, Applied Microbiology and Biotechnology, Toxicology, chemistry.chemical_compound, chemistry, Botany, Soil fertility, education, Carbofuran, Biotechnology
Abstract

Among the four insecticides under study, hexachlorocyclohexane (BHC) followed by phorate significantly stimulated the populations of (total) bacteria, actinomycetes, fungi, aerobic non-symbiotic N2-fixing bacteria and P-solubilizing microorganisms in soil. Carbofuran significantly stimulated total as well as N2-fixing bacteria. Fenvalerate had no effect on P-solubilizers. All the insecticides stimulated the proportion of Penicillium in soil. Similarly, Pseudomonas with BHC, Sarcina with phorate, Corynebacterium, Azotobacter and Streptomyces with fenvalerate were also stimulated. On the other hand, Erysipelothrix with BHC, Staphylococcus with phorate, Staphylococcus, Nocardia and Fusarium with fenvalerate were inhibited. Almost all the insecticides reduced the proportions of Micrococcus and Rhizopus in soil. Insecticides also augmented the non-symbiotic N2-fixing and P-solubilizing capacities of the soil and the augmentation was more pronounced with BHC followed by phorate.

Published
1998

13. Azimuthal anisotropy in S + Au reactions at 200 A GeV

Author

M.M. Aggarwal, A.L.S. Angelis, V. Antonenko, T.C. Awes, S.K. Badyal, C. Barlag, K.B. Bhalla, V.S. Bhatia, C. Blume, D. Bock, E.-M. Bohne, D. Bucher, A. Buijs, S. Chattopadhyay, A. Claussen, G. Clewing, A.C. Das, null Devanand, P. Dönni, E. Durieux, M.R. Dutta Majumdar, P. Foka, S. Fokin, M.S. Ganti, S. Garpman, F. Geurts, T.K. Ghosh, R. Glasow, S.K. Gupta, H.-Å. Gustafsson, H.H. Gutbrod, M. Hartig, Xiaochun He, G. Hölker, M. Ippolitov, M. Izycki, S. Kachroo, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, B.W. Kolb, I. Langbein, J. Langheinrich, A. Lebedev, H. Löhner, S. Loknathan, V. Manko, M. Martin, I.S. Mittra, S. Mookerjee, H. Naef, S.K. Nayak, T.K. Nayak, S. Nikolaev, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, T. Peitzmann, F. Plasil, M. Purschke, S. Raniwala, N.K. Rao, L. Rosselet, B. Roters, J.M. Rubio, S. Saini, S. Sambyal, R. Santo, H.R. Schmidt, T. Siemiarczuk, R.H. Siemssen, B.C. Sinha, S. Slegt, K. Söderström, N. Solomey, S.P. Sorensen, G. Stefanek, P. Steinhaeuser, E. Stenlund, A. Ster, D. Stüken, M.D. Trivedi, C. Twenhoefel, N. Van Eijndhoven, W.H. Van Heeringen, A. Vinogradov, Y.P. Viyogi, S. Weber, G.R. Young, KVI - Center for Advanced Radiation Technology, Research unit Nuclear & Hadron Physics, Angelis, Aris, Donni, Paul, Durieux, Eric Marie Geoffroy, Foka, Panagiota, Kalechofsky, Hal, Martin, Michel, Naef, Hanspeter, Rosselet, Laurent, Rubio, Juan Miguel, and Solomey, Nickolas

Subjects
Physics, Nuclear and High Energy Physics, Photon, biology, Physics::Instrumentation and Detectors, COLLECTIVE FLOW, Detector, Venus, ddc:500.2, HEAVY-ION COLLISIONS, biology.organism_classification, ENERGY, Azimuth, Nuclear physics, NUCLEUS COLLISIONS, Multiplicity (chemistry), Nuclear Experiment, Anisotropy, Fourier series, Event generator
Abstract

Azimuthal correlations of photons produced at mid-rapidity in 200 A GeV S + Au collisions have been studied using a preshower photon multiplicity detector in the WA93 experiment. The Fourier expansion method has been employed to estimate the event plane via the anisotropy of the event as a function of centrality. The event plane correlation technique has been used to determine the true event anisotropy, beyond the anisotropy which arises due to finite multiplicity. The VENUS event generator with rescattering and proper simulation of the detector response can explain only a portion of the observed anisotropy. The residual anisotropy is found to be of the order of 5% for semi-central collisions. This suggests that directed collective flow of the produced particles is present at SPS energies. (C) 1997 Published by Elsevier Science B.V.

Published
1997

14. Effects of neutral dynamics in a partially ionised plasma

Author

A.A Sheikh and A.C Das

Subjects
Physics, Atmospheric Science, Relative velocity, Aerospace Engineering, Astronomy and Astrophysics, Plasma, Low frequency, Ion, Geophysics, Physics::Plasma Physics, Space and Planetary Science, Ionization, Phase (matter), Dispersion relation, Compressibility, General Earth and Planetary Sciences, Atomic physics
Abstract

Considering the basic equations of plasma and neutral fluids, it is shown, theoretically, how neutral dynamics gives rise to various modes in inhomogeneous, magnetized, and partially ionized plasma observed in space as well as in laboratory plasma. The most general dispersion relation which can describe almost all the modes in the system has been obtained. We have shown that the presence of relative velocity between ions and neutrals, compressibility nature of neutrals and gravity gives rise to a few new low frequency modes. The sources of free energy for the onset of various modes are identified. The effect of coupling of neutral dynamics with plasma pinching force ( J × B ) has been highlighted. It is shown that the phase velocities and the growth rates are very sensitive to the ratio of neutrals with ions and the scale heights associated with inhomogeneities. The potential application of the theoretical results is discussed.

Published
1997

15. Particle acceleration by kinetic Alfvén waves in the IO plasma torus

Author

A.C. Das and Wing-Huen Ip

Subjects
Physics, Hiss, Magnetosphere, Astronomy and Astrophysics, Torus, Plasma, Electron, Computational physics, Magnetic field, Particle acceleration, Classical mechanics, Physics::Plasma Physics, Space and Planetary Science, Surface wave, Physics::Space Physics
Abstract

The generation of surface waves due to a strong gradient in the plasma density and its coupling to kinetic Alfven waves near the Io plasma torus are found to be a viable mechanism for particle acceleration leading to a beam of energetic electrons along the magnetic field. It is shown that acceleration to a few kiloelectronvolts is possible and this might explain the intense auroral hiss observed near the inner edge of the Io plasma torus by Voyager 1.

Published
1992

16. Instability of electrostatic waves in nonuniform weakly ionized magnetized plasmas

Author

A.C. Das, C. B. Dwivedi, R. Bharuthram, and Padma Kant Shukla

Subjects
Fluid Flow and Transfer Processes, Physics, Energetic neutral atom, Computational Mechanics, General Physics and Astronomy, Plasma, Condensed Matter Physics, Electrostatics, Instability, Charged particle, Physics::Plasma Physics, Mechanics of Materials, Ionization, Physics::Space Physics, Electron temperature, Atomic physics, Ionosphere
Abstract

Novel electrostatic instabilities are shown to exist in a weakly ionized magnetoplasma having equilibrium density and electron temperature gradients. The growth rate of the instabilities critically depends on collisions between charged particles and neutral atoms. It is suggested that the present instabilities could be potential candidates for generating enhanced fluctuations during strong auroral activities in the E region of Earth’s ionosphere, in cometary plasmas, as well as in controlled laboratory experiments.

Published
1992

17. Neutral induced low frequency instability in a weakly ionized magnetized plasma

Author

C.B. Dwivedi and A.C. Das

Subjects
Physics, Two-stream instability, Space and Planetary Science, Ionization, Dispersion relation, Astronomy and Astrophysics, Cyclotron radiation, Plasma, Atomic physics, Ionosphere, Instability, Magnetic field
Abstract

Using a three-fluid model, a linear local analysis of neutral induced low frequency (NILF) mode instability in an inhomogeneous weakly ionized plasma in a magnetic field has been carried out. It is concluded that this novel instability, electro-mechanical in nature, is seeded by the neutrals and is driven by electro-mechanical coupling through the frictional force between the plasma and neutral fluids. The condition for the onset of the instability requires a finite neutral diffusion flow. It is proposed that the NILF mode can provide a physical mechanism to understand the nature and cause of the observed irregularities in the D -region of the Earth's ionosphere [Thrane, E. V. and Grandal, B. (1981) J. atmos. terr. Phys. 43 , 179; Sinha, H. S. S. (1992) J. atmos. terr. Phys. 54 , 49]. However, its general application in any weakly ionized plasma with an ambient magnetic field is not restricted.

Published
1992

18. Search for disoriented chiral condensates in 158.A GeV Pb + Pb collisions

Author

Tapan K. Nayak, M.M. Aggarwal, A. Agnihotri, Z. Ahammed, A.L.S. Angelis, V. Antonenko, V. Arefiev, V. Astakhov, V. Avdeitchikov, T.C. Awes, P.V.K.S. Baba, S.K. Badyal, A. Baldine, L. Barabach, C. Barlag, S. Bathe, B. Batiounia, T. Bernier, K.B. Bhalla, V.S. Bhatia, C. Blume, R. Bock, E.-M. Bohne, D. Bucher, A. Buijs, E.-J. Buis, H. Büsching, L. Carlen, V. Chalyshev, S. Chattopadhyay, K.E. Chenawi, R. Cherbatchev, T. Chujo, A. Claussen, A.C. Das, M.P. Decowski, V. Djordjadze, P. Donni, I. Doubovik, M.R. Dutta Majumdar, S. Eliseev, K. Enosawa, H. Feldmann, P. Foka, S. Fokin, V. Frolov, M.S. Ganti, S. Garpman, O. Gavrishchuk, F.J.M. Geurts, T.K. Ghosh, R. Glasow, S.K. Gupta, B. Guskov, H.A. Gustafsson, H.H. Gutbrod, R. Higuchi, I. Hrivnacova, M. Ippolitov, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, K. Karpio, S. Kato, S. Kees, H. Kim, B.W. Kolb, I. Kosarev, I. Koutcheryaev, A. Kugler, P. Kulinich, V. Kumar, M. Kurata, K. Kurita, N. Kuzmin, I. Langbein, A. Lebedev, Y.Y. Lee, H. Löhner, D.P. Mahapatra, V. Manko, M. Martin, A. Maximov, R. Mehdiyev, G. Mgebrichvili, Y. Miake, D. Mikhalev, G.C. Mishra, Y. Miyamoto, B. Mohanty, D. Morrison, D.S. Mukhopadhyay, V. Myalkovski, H. Naef, B.K. Nandi, S.K. Nayak, T.K. Nayak, S. Neumaier, A. Nianine, V. Nikitine, S. Nikolaev, S. Nishimura, P. Nomokov, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, M. Pachr, A. Parfenov, S. Pavliouk, T. Peitzmann, V. Petracek, F. Plasil, M.L. Purschke, B. Raeven, J. Rak, S. Raniwala, V.S. Ramamurthy, N.K. Rao, F. Retiere, K. Reygers, G. Roland, L. Rosselet, I. Roufanov, J.M. Rubio, S.S. Sambyal, R. Santo, S. Sato, H. Schlagheck, H.-R. Schmidt, G. Shabratova, I. Sibiriak, T. Siemiarczuk, B.C. Sinha, N. Slavine, K. Söderström, N. Solomey, S.P. Sørensen, P. Stankus, G. Stefanek, P. Steinberg, E. Stenlund, D. Stüken, M. Sumbera, T. Svensson, M.D. Trivedi, A. Tsvetkov, C. Twenhöfel, L. Tykarski, J. Urbahn, N.v. Eijndhoven, W.H.v. Heeringen, G.J.v. Nieuwenhuizen, A. Vinogradov, Y.P. Viyogi, A. Vodopianov, S. Vörös, M.A. Vos, B. Wyslouch, K. Yagi, Y. Yokota, and G.R. Young

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Photon, Phase space, Charged particle, Nuclear Physics
Abstract

The authors have studied the production of hadrons and photons in the reaction Pb(Pb, X) at 158 A.GeV. They have applied the discrete wavelet transform to the photon and charged-particle correlations in order to obtain a set of father function coefficients. They try to explain the multiplicity fluctuations by means of localized disoriented chiral condensate domains. (7 refs). A detailed analysis of the phase space distributions of charged particles and photons have been carried out using two independent methods. The results indicate the presence of nonstatistical fluctuations in localized regions of phase space.

Published
2000

19. Present Status and Future of DCC Analysis

Author

Tapan K. Nayak, M.M. Aggarwal, A. Agnihotri, Z. Ahammed, A.L.S. Angelis, V. Antonenko, V. Arefiev, V. Astakhov, V. Avdeitchikov, T.C. Awes, P.V.K.S. Baba, S.K. Badyal, A. Baldine, L. Barabach, C. Barlag, S. Bathe, B. Batiounia, T. Bernier, K.B. Bhalla, V.S. Bhatia, C. Blume, R. Bock, E.-M. Bohne, D. Bucher, A. Buijs, E.-J. Buis, H. Büsching, L. Carlen, V. Chalyshev, S. Chattopadhyay, K.E. Chenawi, R. Cherbatchev, T. Chujo, A. Claussen, A.C. Das, M.P. Decowski, V. Djordjadze, P. Donni, I. Doubovik, M.R. Dutta Majumdar, S. Eliseev, K. Enosawa, H. Feldmann, P. Foka, S. Fokin, V. Frolov, M.S. Ganti, S. Garpman, O. Gavrishchuk, F.J.M. Geurts, T.K. Ghosh, R. Glasow, S.K. Gupta, B. Guskov, H.A. Gustafsson, H.H. Gutbrod, R. Higuchi, I. Hrivnacova, M. Ippolitov, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, K. Karpio, S. Kato, S. Kees, H. Kim, B.W. Kolb, I. Kosarev, I. Koutcheryaev, A. Kugler, P. Kulinich, V. Kumar, M. Kurata, K. Kurita, N. Kuzmin, I. Langbein, A. Lebedev, Y.Y. Lee, H. Löhner, D.P. Mahapatra, V. Manko, M. Martin, A. Maximov, R. Mehdiyev, G. Mgebrichvili, Y. Miake, D. Mikhalev, G.C. Mishra, Y. Miyamoto, D. Morrison, D.S. Mukhopadhyay, V. Myalkovski, H. Naef, B.K. Nandi, S.K. Nayak, T.K. Nayak, S. Neumaier, A. Nianine, V. Nikitine, S. Nikolaev, S. Nishimura, P. Nomokov, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, M. Pachr, A. Parfenov, S. Pavliouk, T. Peitzmann, V. Petracek, F. Plasil, M.L. Purschke, B. Raeven, J. Rak, S. Raniwala, V.S. Ramamurthy, N.K. Rao, F. Retiere, K. Reygers, G. Roland, L. Rosselet, I. Roufanov, J.M. Rubio, S.S. Sambyal, R. Santo, S. Sato, H. Schlagheck, H.-R. Schmidt, G. Shabratova, I. Sibiriak, T. Siemiarczuk, B.C. Sinha, N. Slavine, K. Söderström, N. Solomey, S.P. Sørensen, P. Stankus, G. Stefanek, P. Steinberg, E. Stenlund, D. Stüken, M. Sumbera, T. Svensson, M.D. Trivedi, A. Tsvetkov, C. Twenhöfel, L. Tykarski, J. Urbahn, N.v. Eijndhoven, W.H.v. Heeringen, G.J.v. Nieuwenhuizen, A. Vinogradov, Y.P. Viyogi, A. Vodopianov, S. Vörös, M.A. Vos, B. Wyslouch, K. Yagi, Y. Yokota, and G.R. Young

Subjects
Quantum chromodynamics, Physics, Nuclear and High Energy Physics, High energy, Chiral symmetry, Particle physics, High Energy Physics::Lattice, Nuclear Theory, High Energy Physics::Phenomenology, FOS: Physical sciences, Current analysis, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Pion, Heavy ion, Nuclear Experiment, Analysis method, Particle Physics - Experiment
Abstract

Disoriented Chiral Condensates (DCC) have been predicted to form in high energy heavy ion collisions where the approximate chiral symmetry of QCD has been restored. This leads to large imbalances in the production of charged to neutral pions. Sophisticated analysis methods are being developed to disentangle DCC events out of the large background of events with conventionally produced particles. We present a short review of current analysis methods and future prospects., 12 pages, 5 figures. Invited talk presented at the 13th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 97), Tsukuba, Japan, 1-5 Dec 1997

Published
1998

20. Event by event measurement of〈pT〉of photons in S + Au collisions at 200 A·GeV

Author

M.M. Aggarwal, A.L.S. Angelis, V. Antonenko, T.C. Awes, S.K. Badyal, C. Barlag, K.B. Bhalla, V.S. Bhatia, C. Blume, D. Bock, E.-M. Bohne, D. Bucher, A. Buijs, S. Chattopadhyay, A. Claussen, G. Clewing, A.C. Das, null Devanand, P. Dönni, E. Durieux, M.R. Dutta Majumdar, S. Fokin, M.S. Ganti, S. Garpman, F. Geurts, T.K. Ghosh, R. Glasow, S.K. Gupta, H.-Å. Gustafsson, H.H. Gutbrod, M. Hartig, He Xiaochun, G. Hölker, M. Ippolitov, M. Izycki, S. Kachroo, R. Kamermans, K.-H. Kampert, K. Karadjev, B.W. Kolb, I. Langbein, J. Langheinrich, A. Lebedev, H. Löhner, V. Manko, M. Martin, I.S. Mittra, H. Naef, S.K. Nayak, T.K. Nayak, S. Nikolaev, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, T. Peitzmann, F. Plasil, M. Purschke, S. Raniwala, N.K. Rao, L. Rosselet, B. Roters, J.M. Rubio, S. Saini, S. Sambyal, R. Santo, H.R. Schmidt, T. Siemiarczuk, R. Siemssen, B.C. Sinha, S. Slegt, K. Söderström, N. Solomey, S.P. Sorensen, G. Stefanek, P. Steinhaeuser, E. Stenlund, A. Ster, D. Stüken, M.D. Trivedi, C. Twenhoefel, N. Van Eijndhoven, W.H. Van Heeringen, A. Vinogradov, Y.P. Viyogi, S. Weber, G.R. Young, Angelis, Aris, Donni, Paul, Durieux, Eric Marie Geoffroy, Martin, Michel, Naef, Hanspeter, Rosselet, Laurent, Rubio, Juan Miguel, and Solomey, Nickolas

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Photon, Large Hadron Collider, biology, Venus, ddc:500.2, biology.organism_classification, Spectral line, Nuclear physics, Transverse plane, Transverse momentum, Multiplicity (chemistry), Nuclear Experiment, Event generator
Abstract

The mean transverse momentum of photons has been determined on an event by event basis in S + Au collisions at 200 A.GeV from the ratio of the measured electromagnetic transverse energy (E-T(em)) to the photon multiplicity (N-gamma). The average value obtained is similar to that determined for the same system using spectroscopic techniques. The centrality dependence of the measured values are in agreement with the predictions of the VENUS event generator. (C) 1997 Published by Elsevier Science B.V.

Published
1997

21. Photon and neutral meson production in 158 AGeV 208Pb+Pb collisions

Author

Thomas Peitzmann, M. Aggarwal, A. Agnihotri, A.L.S. Angelis, V. Antonenko, V. Arefiev, V. Astakhov, V. Avdeitchikov, T.C. Awes, S.K. Badyal, A. Baldine, L. Barabach, C. Barlag, S. Bathe, B. Batiounia, T. Bernier, K.B. Bhalla, V.S. Bhatia, C. Blume, D. Bock, R. Bock, E.-M. Bohne, D. Bucher, A. Buijs, E.-J. Buis, H. Büsching, L. Carlen, V. Chalyshev, S. Chattopadhyay, K.E. Chenawi, R. Cherbatchev, T. Chujo, A. Claussen, A.C. Das, M.P. Decowski, null Devanand, V. Djordjadze, P. Donni, I. Doubovik, S. Eliseev, K. Enosawa, H. Feldmann, P. Foka, S. Fokin, V. Frolov, M.S. Ganti, S. Garpman, O. Gavrishchuk, F.J.M. Geurts, T.K. Ghosh, R. Glasow, B. Guskov, H.A. Gustafsson, H.H. Gutbrod, R. Higuchi, I. Hrivnacova, M. Ippolitov, H. Kalechofsky, R. Kamermans, K.-H. Kampert, K. Karadjev, K. Karpio, S. Kato, S. Kees, H. Kim, B.W. Kolb, I. Kosarev, I. Koutcheryaev, A. Kugler, P. Kulinich, V. Kumar, M. Kurata, K. Kurita, N. Kuzmin, I. Langbein, A. Lebedev, Y.Y. Lee, H. Löhner, D.P. Mahapatra, J. Maharana, M.D.D. Majumdar, V. Manko, M. Martin, A. Maximov, R. Mehdiyev, G. Mgebrichvili, Y. Miake, D. Mikhalev, G.C. Mishra, I.S. Mittra, Y. Miyamoto, S. Mookerjee, D. Morrison, D.S. Mukhopadhyay, V. Myalkovski, H. Naef, G.K. Nandi, S.K. Nayak, T.K. Nayak, S. Neumaier, A. Nianine, V. Nikitine, S. Nikolaev, S. Nishimura, P. Nomokov, J. Nystrand, F.E. Obenshain, A. Oskarsson, I. Otterlund, M. Pachr, A. Parfenov, S. Pavliouk, T. Peitzmann, V. Petracek, S.C. Phatak, F. Plasil, M.L. Purschke, J. Rak, S. Raniwala, V.S. Ramamurthy, N.K. Rao, B. Raven, F. Retiere, K. Reygers, G. Roland, L. Rosselet, I. Roufanov, J. Rubio, S.S. Sambyal, R. Santo, S. Sato, P. Saxena, H. Schlagheck, H.-R. Schmidt, G. Shabratova, I. Sibariak, T. Siemiarczuk, K. Singh, B.C. Sinha, N. Slavine, K. Söderström, N. Solomey, S.P. Sørensen, P. Stankus, G. Stefanek, P. Steinberg, E. Stenlund, D. Stüken, M. Sumbera, T. Svensson, M.D. Trivedi, A. Tsvetkov, C. Twenhöfel, L. Tykarski, J. Urbahn, N.v. Eijndhoven, W.H.v. Heeringen, G.J.v. Nieuwenhuizen, A. Vinogradov, Y.P. Viyogi, A. Vodopianov, M.A. Vos, B. Wyslouch, K. Yagi, Y. Yokota, G.R. Young, Angelis, Aris, Doenni, Paul, Foka, Panagiota, Kalechofsky, Hal, Martin, Michel, Naef, Hanspeter, Rosselet, Laurent, Rubio, Juan Miguel, and Solomey, Nickolas

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, Transverse plane, Large Hadron Collider, Photon, Meson production, Nuclear Theory, High Energy Physics::Experiment, ddc:500.2, Multiplicity (chemistry), Nuclear Experiment
Abstract

First results from the WA98 experiment on 33 TeV 208 Pb ion reactions with various targets measured at the CERN SPS are presented. Data on transverse energy production and particle multiplicity are discussed. Special emphasis is laid on photon and neutral meson production.

Published
1996

22. Generation of ionospheric irregularities by thermal-source: A new mechanism

Author

A.C. Das and U.N. Das

Subjects
Physics, Ionospheric dynamo region, Astronomy and Astrophysics, F region, Instability, Magnetic field, Computational physics, Space and Planetary Science, Electric field, Physics::Space Physics, Heat transfer, Diffusion (business), Atomic physics, Ionosphere
Abstract

A new mechanism for the generation of ionospheric irregularities of scale sizes of the order of 100 m or more, has been developed on the basis of thermal energy source due to collisional current dissipation. The important role is played by the diffusion of particles along and across the magnetic field. The threshold condition for the instability has been obtained and it is shown that these irregularities can be generated in the F-region height of auroral ionosphere when the electric field is enhanced to about 10 mV m −1 .

Published
1983

23. Frequency-time structure of vlf emissions

Author

V.H. Kulkarni and A.C. Das

Subjects
Physics, Frequency response, Classical mechanics, Amplitude, Whistler, Space and Planetary Science, Plane (geometry), Phase (waves), Particle, Astronomy and Astrophysics, Computational physics, Pulse (physics), Magnetic field
Abstract

Non-linear wave-particle interaction in the whistler mode in a non-uniform magnetic field is considered. The effect of the second order resonant particles arising due to nonuniformity of the ambient magnetic field is found to be dominant near the equatorial plane of the Earth. The equations describing the time development of the amplitude and phase of the wave packet have been solved numerically by computing the resonant particle current in a self-consistent manner. The growth of the waves because of trapped particles is found to be substantial for triggering an emission and the changes in phase lead to the frequency-time structure. It is capable of reproducing all kinds of frequency time structure as observed in the case of a morse pulse.

Published
1975

24. Excitation of ULF and VLF waves in the ionosphere

Author

Padma Kant Shukla, S. Bujarbarua, and A.C. Das

Subjects
Physics, Whistler, Analytical expressions, Astronomy and Astrophysics, Geophysics, Plasma, Instability, Physics::Geophysics, Space and Planetary Science, Physics::Space Physics, Topside ionosphere, Wave structure, Ionosphere, Excitation
Abstract

It is shown that a two-dimensional lower-hybrid wave structure can parametrically trigger the growth of VLF and ULF noises in a plasma. Analytical expressions for the increment and threshold of the instability are obtained. Application of our work to the auroral zones of the topside ionosphere is discussed.

Published
1980

25. VLF emissions and substorm activity

Author

V.H. Kulkarni and A.C. Das

Subjects
Physics, Whistler, Field (physics), Astronomy and Astrophysics, Plasmasphere, Electron, Geophysics, Magnetic field, Computational physics, Space and Planetary Science, Physics::Space Physics, Substorm, Phase velocity, Current (fluid)
Abstract

The resonant interaction between the whistler mode waves and the energetic electrons near the plasmapause boundary has been studied in the presence of field aligned currents which seem to exist during substorm activity. It is shown that the electrons which carry the current along the direction of the magnetic field enhance the whistler mode growth considerably if the streaming velocity is small compared to the phase velocity of the wave. It is likely that this is one of the mechanisms explaining the intense VLF emissions observed near the plasmapause during substorm activity.

Published
1977

26. Ecology of soil fungi of rice fields 1. Succession of fungi on rice roots 2. Association of soil fungi with organic matter

Author

A.C. Das

Subjects
chemistry.chemical_classification, education.field_of_study, Thielavia, biology, Ecology, Soil biology, Population, biology.organism_classification, Crop, chemistry, Botany, Penicillium, General Earth and Planetary Sciences, Paddy field, Organic matter, Cover crop, education, General Environmental Science
Abstract

The composition of the fungal community associated with the roots changes with the ageing of the crop. In the early stages of growth species of Aspergillus and Penicillium are common isolates, but specialized root inhabitants like Thielavia angulata Das and Humicola sp. occur dominantly on mature roots. Trichoderma viride Pers. ex Fr. and Cephalosporium sp. may be associated with roots of all ages to a more or less varying degree, but they tend to become prominent only on dead and decomposing roots left in the field after harvesting, when only a minimum number of species is present. These roots are almost exhausted by March and only the more resistant parts left. Dominant fungi isolated in March and April were mainly sterile and could not be identified, though Aspergillus and Penicillium species reappeared with lesser frequency. In the second part the composition of the fungus population of a paddy field soil in relation to soil factors and amendments, cover crops and weather is described. Most of the fungi capable of growing on malt agar plates may be isolated either by the dilution plate method or by plating washed organic matter picked up from soil samples, but indication of their activities in soil is better secured by the latter technique. Of thirty-two fungi only nine were more or less dominant, occurring in almost every month, the rest were rather rare. Marked seasonal variation of the dominant fungi occurred, but soil treatments affected only a few of them. It is suggested that the greater frequency of isolation of some fungi from washed organic matter is due to their greater saprophytic ability to colonize organic debris in this soil.

Published
1963

27. New species of Thielavia and Sordaria

Author

A.C. Das

Subjects
Thielavia, biology, Ecology, Variospora, Botany, General Earth and Planetary Sciences, Sordaria, biology.organism_classification, Ascus, General Environmental Science
Abstract

Thielavia angulata sp.nov. and Sordaria bosensis sp.nov. isolated from soil of a paddy field at Falta, about 35 miles from Calcutta, are described. The former is close to T. variospora Cain, but differs distinctly from the latter in shape and size of ascus and ascospores which are wider and more angular. S. bosensis is close to S. minima Sacc. & Speg., which is now considered a nomen ambiguum.

Published
1962

28. Effect of trapped particles in an electrostatic wave on the whistler mode

Author

A.C Das and V.H Kulkarni

Subjects
Physics, Sideband, Whistler, Wave propagation, General Physics and Astronomy, Resonance, Electron, Magnetic field, Amplitude, Physics::Plasma Physics, Quantum mechanics, Dispersion relation, Physics::Space Physics, Atomic physics
Abstract

It is shown that there exists a new series of resonances due to the interaction between a whistler propagating along an ambient magnetic field and the particles which are trapped in a large amplitude electrostatic wave. These resonances seem to produce sideband growths of the whistler.

Published
1975

29. Decay of electrostatic ion cyclotron waves

Author

Padma Kant Shukla, M. Y. Yu, and A.C. Das

Subjects
Physics, Auroral zone, Cyclotron, Kinetic energy, Finite amplitude, Ion, law.invention, Alfvén wave, Geophysics, Amplitude, Physics::Plasma Physics, law, Quantum electrodynamics, Physics::Space Physics, General Earth and Planetary Sciences, Atomic physics, Ionosphere
Abstract

It is shown that finite amplitude electrostatic ion cyclotron (EIC) waves can parametrically decay into daughter EIC waves and kinetic Alfven waves. Since the current associated with the latter is d.c. in the EIC time scale, it can linearly excite EIC waves when the amplitude of the Alfven waves is sufficiently high. This provides a mechanism for the simultaneous existence of EIC and Alfven fluctuations. Application of the theory in the auroral zone of the ionosphere is discussed.

Published
1984

30. Resonance instability of small-scale field-aligned irregularities

Author

A.C. Das and J.A. Fejer

Subjects
Physics, Atmospheric Science, Ecology, Scale (ratio), Condensed matter physics, Ionospheric electron density, Paleontology, Soil Science, Resonance, Forestry, Aquatic Science, Oceanography, Plasma oscillation, Instability, Plasma resonance, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Atomic physics, Field aligned irregularities, Earth-Surface Processes, Water Science and Technology
Published
1979

31. Excitation of convection cells by ion-cyclotron waves

Author

A.C. Das, Padma Kant Shukla, and H. U. Rahman

Subjects
Physics, Modulational instability, Coupling (physics), Condensed matter physics, Physics::Plasma Physics, Differential equation, Wave propagation, Quantum electrodynamics, Dispersion relation, General Engineering, Wave equation, Rayleigh–Bénard convection, Convection cell
Abstract

It is shown that convective cells can be excited by large‐amplitude propagating ion‐cyclotron waves in a plasma. Using the two‐fluid model, a coupled set of differential equations is obtained. A nonlinear dispersion relation for the modulational instability is then derived. This relation is investigated for different parameter regimes and expressions for the growth rates are obtained analytically. Relevance of the work to space physics as well as magnetically confined plasmas is discussed.

Published
1981

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