Central Institute of Technology Kokrajhar | Profile
Dr. Samiran Das

Dr. Samiran Das

Associate Professor

Former HoD
Former Member of SENATE
Member of Library Management Committee
Warden
  +91 9101802681   s.das@cit.ac.in

Research Interest:

Plasma Physics ∎ Fluid Dynamics ∎ Mathematics Education
Address
Department of Mathematics (Room No 204)
Central Institute of Technology Kokrajhar
BTAD Assam India 783370
Education
M.Sc. (GU), NET (CSIR), Ph.D. (GU)

Title: Investigation of Nonlinear Waves in Plasmas

Supervisor: Prof. Bhaben Chandra Kalita

                       Department of Mathematics

                       Gauhati University, Guwahati, Assam

  • Awarded:    01

  • Submitted:  01

  • Ongoing:    02

  • IUPAP Fellowship: Partial Support to attend and present paper in the international conference “XXIX IUPAP Conference on Computational Physics (CCP 2017)”, 9-13 July 2017, Paris, France held in Jussieu campus (Latin Quarter) of the University Pierre et Marie Curie-Sorbonne.

  • International Travel Support (ITS): Travel grant under ‘International Travel Support (ITS)’ scheme by SERB to attend “XXX IUPAP Conference on Computational Physics 2018 (CCP 2018)”, USA (29 July to 02 August, 2018) held in University of California, Davis, California, USA.

  • IUPAP Fellowship: Financial support for “XXX IUPAP Conference on Computational Physics 2018 (CCP 2018)”, USA (29 July to 02 August, 2018) held in University of California, Davis, California, USA.

  • BEST POSTER AWARD: Received the second BEST POSTER AWARD in the XXXII IUPAP Conference on Computational Physics (CCP2021), 1-5August 2021, Coventry, UK hosted by Centre for Fluid and Complex Systems, Faculty of Engineering, Computing and Mathematics, Coventry University, Coventry, England for the paper entitled “Weakly relativistic effect in the formation of ion-acoustic solitary waves in dusty plasma”.

  • Life Member of Indian Science Congress Association (ISCA), Kolkata, India (Membership No.-L 25587).

  • Life Member of Indian Mathematical Society (Membership No.-L/2022/49).

  • Member of Division of Plasma Physics, Association of Asia Pacific Physical Societies (AAPPS-DPP) (Membership Id- 3002).

  • Member of Calcutta Mathematical Society.

Journals

1. B. C. Kalita and Samiran Das, Dust ion acoustic (DIA) solitary waves in plasmas with weak relativistic effects in electrons and ions, Astrophysics and Space Science, 352(2), 585-592, Springer, SCI, 2014.

2. B.C. Kalita, S. Das and D. Bhattacharjee , “Determination of the measure of size (amplitude) of perturbation and its role in the process of enforcing discrete Korteweg-de Vries solitons to modified Korteweg-de Vries solitons as means of continuum hypothesis in a multi-component dusty plasma” Physics of Plasmas, vol. 24(10), p. 102121, 2017.

3. B.C. Kalita and S. Das, “Comparative study of dust ion acoustic Korteweg-de Vries and modified Korteweg-de Vries solitons in dusty plasmas with variable temperatures”, Journal of Plasma Physics, vol. 83(5), p. 905830502, 2017.

4. B.C. Kalita and Samiran Das, “Weakly Relativistic Ion-Acoustic Solitary Waves in Dusty Plasma” IEEE Transactions on Plasma Science, vol. 46(4), pp. 790-796, 2017.

5. Samiran Das, “Propagation of dust ion acoustic solitary waves in dusty plasma with Boltzmann electrons” Journal of Physics: Conference Series, vol. 1290, p. 012025, 2019.

6. S. Das and I. Ali, “Dust-Ion Acoustic Solitary Waves in Dusty Plasma with Cairn's Distributed Electrons” IEEE Transactions on Plasma Science, p.190, 2022, doi:10.1109/ICOPS37625.2020.9717729.

7. Imdad Ali and Samiran Das, “Factors Affecting Algebraic Problem-solving Skills of Secondary School Students” International Journal of Educational Sciences, 35(1-3), pp. 22-28, 2021.

8. Samiran Das,” Weak Relativistic Effect in the Formation of Ion-Acoustic Solitary Waves in Dusty Plasma”, IEEE Transactions on Plasma Science, vol. 50(7), pp. 2225-2229, 2022.

9. Imdad Ali and Samiran Das, “The Influence of Study Habits and Parental Involvement on Algebraic Problem-Solving Achievement” International Journal of Educational Sciences, vol. 38 (1-3), pp. 55-61, 2022.

10. Samiran Das and Dulal Chandra Das, “Higher-order nonlinear dust ion acoustic (DIA) solitary waves in plasmas with weak relativistic effects in electrons and ions” The European Physical Journal D, vol. 77(3), 39, 2023.

11. Samiran Das and Imdad Ali, “An investigation on the effects of attitude towards algebraic problem solving achievement” International Journal of Evaluation and Research in Education (IJERE), vol. 12(2), 1016-1022, 2023.

12. Samiran Das and Dulal Chandra Das, “Compressive and rarefactive dust ion-acoustic Korteweg-de Vries and modified Korteweg-de Vries solitons in a multi-component dusty plasma” Journal of the Korean Physical Society, pp. 1-7, 2023.

13. Samiran Das and Dulal Chandra Das, “Compressive and rarefactive dust ion-acoustic Korteweg-de Vries and modified Korteweg-de Vries solitons in a multi-component dusty plasma” Journal of the Korean Physical Society, pp. 1-7, 2023.

14. Samiran Das and Dulal Chandra Das, “Nonlinear propagation of dust ion-acoustic solitary waves in a dusty plasma with weak relativistic electrons” Indian Journal of Physics, pp. 1-8, 2023.

15. Dulal Chandra Das and Samiran Das, “Propagation of higher order compressive dust-ion acoustic solitary waves in a dusty plasma with weak relativistic electrons” Journal of the Korean Physical Society, vol. 84, pp. 231–241, 2023.

16. Bhaben Chandra Kalita, Rekha Kalita and Samiran Das, “Dust ion acoustic solitary waves in plasma with cairns distributed electrons and new classical distribution of ions” Astrophysics, vol. 67(1), pp. 91-103, 2024.

17. Dulal Chandra Das, Samiran Das and Rekha Kalita, “Modified Korteweg−de Vries solitons with quartic nonlinearity in a dusty plasma” Physica Scripta, vol. 99, pp. 055266, 2024.

18. Samiran Das and Dulal Chandra Das, “Comparative study of small amplitude dust ion acoustic Korteweg-de Vries and modified Korteweg-de Vries solitons in a dusty plasma with weak relativistic electrons” Springer Proceedings in Physics, vol. 405, pp. 39-55, 2024.

19. Imdad Ali and Samiran Das, “The mediating effect of study habits in the relationship between parental involvement and algebraic problem-solving achievement” International Journal of Evaluation and Research in Education (IJERE), Accepted.

20. Imdad Ali, Samiran Das, “Direct and Indirect Effect of Self- Efficacy, Anxiety and Interest on Algebraic Problem-Solving Achievement” Mathematics Teaching Research Journal, vol. 16(2), pp. 102-118, 2024.

Book Chapter

Chapter 16: Determination of Dust Ion Acoustic Solitary Waves in Dusty Plasma with Boltzmann Electrons (DOI: 10.9734/bpi/nvst/v10/14539D), New Visions in Science and Technology (Vol. 10, pp. 157-167), Print ISBN: 978-93-5547-244-1, e Book ISBN: 978-93-5547-245-8 (DOI: 10.9734/bpi/nvst/v10), B P International. (Editor: Dr. Giovanni Bucci, Professor, Dept. of Industrial Engineering and Information and Economy, University of L’Aquila, Italy)

Conferences

1. B. C. Kalita and Samiran Das, “Dust Ion Acoustic Solitary Waves in Plasma with Relativistic Effects” XXXIst International Conference on Phenomena in Ionized Gases (ICPIG), July 14-19, 2013, Granada, Spain.

2. B. C. Kalita and Samiran Das, “Solitary Waves in Dusty Plasma with Pressure Variations in both Electrons and Ions” International Conference on Quantum, Atomic, Molecular and Plasma Physics (QuAMP), September 1-4, 2015, University of Sussex, Brighton, UK.

3. Samiran Das  and Bhaben Chandra Kalita, “Investigation of dust ion acoustic (DIA) solitons in multicomponent plasma with relativistic ions and Cairns distributed électrons” XXIXth IUPAP Conference on Computational Physics, Paris, France 9-13 July 2017.

4. Bhaben Chandra Kalita and Samiran Das, “Propagation of Dust-Ion Acoustic (DIA) waves in multi-species plasma with Cairn's distributed electrons, quantum effects in inertia less electrons and ions” XXIXth IUPAP Conference on Computational Physics, Paris, France 9-13 July 2017.

5. Samiran Das, “Propagation of Dust-Ion Acoustic (DIA) Solitary Waves in Dusty Plasma with Boltzmann electrons” XXX IUPAP Conference on Computational Physics, University of California, Davis, USA, July 29-August 2, 2018.

6. Samiran Das and Imdad Ali, “Dust-Ion Acoustic Solitary Waves in Dusty Plasma With Cairn’s Distributed Electrons” 47th IEEE International Conference on Plasma Science (ICOPS-2020) and 2nd ASIA Pacific Conference on Plasma and Terahertz Science (APCOPTS-2020), virtual, 6-10 Dec 2020, Singapore.

7. Samiran Das, 3rd International Conference on Data Driven Plasma Sciences (ICDDPS-3) and 12th EU-Japan Joint Symposium on Plasma Processing (JSPP-12) / 15th Asia-Pacific Conference on Plasma Science and Technology (APCPST-15), Virtual, 29March-02 April 2021, Osaka University, Japan. PARTICIPATED.

8. Samiran Das, “Weakly relativistic effect in the formation of ion-acoustic solitary waves in dusty plasma” XXXII IUPAP Conference on Computational Physics (CCP2021), virtual, 1-5August 2021, Coventry, UK.

9. Samiran Das and Imdad Ali, “Factors Affecting Algebraic Problem Solving Skills of Secondary School Students in the Morigaon District of Assam, India” 10th International Eurasian Conference on Mathematical Sciences and Applications (IECMSA-2021), virtual, August 25-27, 2021, Sakarya – TURKEY.

10. Samiran Das, 27th INTERNATIONAL CONFERENCE OF INTERNATIONAL ACADEMY OF PHYSICAL SCIENCES (CONIAPS XXVII) On Advances in Relativity and Cosmology (PARC-2021), 26-28 October 2021, BITS Pilani Hyderabad Campus. PARTICIPATED.

11. Samiran Das, 36th National Symposium on Plasma Science and Technology (PLASMA 2021), 13-15 December 2021, BIT Mesra, Jaipur Campus in association with PSSI (virtual). PARTICIPATED.

12. Samiran Das and Imdad Ali, “The Relationship between Study Habits, Parental Involvement and Problem Solving Achievement in Algebra at the Secondary Level” International Conference on Technology and Innovation in Mathematics Education (TIME 2021) held online during 17-19 December, 2021.

13. Dulal Chandra Das and Samiran Das, “Waves in Plasma with special reference to Solitary waves” Virtual National Conference on Plasma Science and Applications (PSA2021), Dec 20-21, 2021, Dept. of Physics, SVNIT, Surat, India.

14. Samiran Das and Dulal Chandra Das, “Nonlinear propagation of dust ion-acoustic solitary waves in a dusty plasma with weak relativistic electrons” 14th International Conference on Plasma Science and Applications (ICPSA 2021), 28-30 December 2021, Nanjing University of Science and Technology, China.

15. Samiran Das and Imdad Ali, “An Investigation on the Effects of Attitude Towards Algebraic Problem Solving Achievement” International Conference on Education in Mathematics, Science and Technology (ICEMST) March 24-27, 2022, Antalya, TURKEY.

16. Samiran Das and D.C. Das, “Dust Ion Acoustic Modified Korteweg-de Vries Solitons in Dusty Plasmas with Boltzmann Electrons” 48th European Conference on Plasma Physics (2022), June 27 to July 1 2022 [Hosted by: DIFFER (Dutch Institute for Fundamental Energy Research), TU/e (Eindhoven University of Technology), UM (Maastricht University)] (Online).

17. Samiran Das and D.C. Das, “Higher Order Solutions for Dust Ion Acoustic Solitons in Complex Plasmas with Relativistic Ions and Cairn’s Distributed Electrons” 48th European Conference on Plasma Physics (2022), June 27 to July 1 2022 [Hosted by : DIFFER (Dutch Institute for Fundamental Energy Research), TU/e (Eindhoven University of Technology), UM (Maastricht University)] (Online).

18. Samiran Das and Dulal Chandra Das, “Compressive and rarefactive dust ion-acoustic Korteweg-de Vries and modified Korteweg-de Vries solitons in a multi-component dusty plasma” 33rd IUPAP Conference on Computational Physics, August 1-4, 2022(Produced and hosted by The University of Texas at Austin | Austin, Texas, USA.

19. Dulal Chandra Das and Samiran Das, “Effect of ion-dust streaming speed in the development of small amplitude dust-ion acoustic solitary waves” 33rd IUPAP Conference on Computational Physics, August 1-4, 2022(Produced and hosted by The University of Texas at Austin | Austin, Texas, USA.

20. Samiran Das and Dulal Chandra Das, “Higher order non-linear dust ion acoustic (DIA) solitary waves in plasmas with weak relativistic effects in electrons and ions” 31st Summer School and International Symposium on the Physics of Ionized Gases (SPIG2022), Sep 5-9, 2022, Belgrade Serbia.

21. Dulal Chandra Das and Samiran Das, “Impact of dust streaming speed on the amplitude and width of solitary waves in a dusty plasma” 34th IUPAP Conference on Computational Physics (CCP2023), August 4-8, 2023, Nagoya University, Kobe, Japan.

22. Samiran Das and Dulal Chandra Das, “Influence of initial streaming speed of weakly relativistic electrons on amplitude of solitary waves in a multi-component dusty plasma” 34th IUPAP Conference on Computational Physics (CCP2023), August 4-8, 2023, Nagoya University, Kobe, Japan.

23. Samiran Das and Dulal Chandra Das, “Effect of Ion and Electron Streamings on Amplitudes of Modified Korteweg-De Vries Solitary Waves in a Weak Relativistic Dusty Plasma (Oral)” 3rd International Conference on Plasma Theory and Simulations (PTS 2023), 21-23 September, 2023, JNU New Delhi.

24. Dulal Chandra Das and Samiran Das, “Modified Korteweg-De Vries Solitons with Quartic Nonlinearity in a Dusty Plasma(Oral)” 3rd International Conference on Plasma Theory and Simulations (PTS 2023), 21-23 September, 2023, JNU New Delhi.

25. Samiran Das and Dulal Chandra Das, “Role of magnetic field in propagation of Dust-Ion Acoustic (DIA) solitary waves in a multi-species dusty plasma with Cairn’s distributed electrons and quantum effect in inertia less electrons (Oral)” 7th Asia-Pacific Conference on Plasma Physics (AAPPS-DPP2023), 12-17 Nov, 2023 at Port Messe Nagoya, Japan.

26. Samiran Das and Dulal Chandra Das, “Comparative study of Dust-Ion-Acoustic modified Korteweg-de Vries solitons in a dusty plasma with cubic and quartic nonlinearity (Poster)” 7th Asia-Pacific Conference on Plasma Physics (AAPPS-DPP2023), 12-17 Nov, 2023 at Port Messe Nagoya, Japan.

27. Samiran Das and Imdad Ali, “The Mediating Role of Mathematics Anxiety in the Relationship between Self-Efficacy and Algebraic Problem Solving of Secondary School Students” International Conference on “Role of Mathematics for the Development of Science and Society (ICRMDSS-2023)”, 21-22 Dec., 2023, Department of Mathematics, Tripura University, Tripura, India (Online).

28. Samiran Das and Dulal Chandra Das, “Comparative study of small amplitude dust ion acoustic Korteweg-de Vries and modified Korteweg-de Vries solitons in a dusty plasma with weak relativistic electrons” 2nd International Conference on Nonlinear Dynamics and Applications (ICNDA2024), 21-23 February, 2024, Department of Mathematics, Sikkim Manipal Institute of Technology, Sikkim.

29. Tirthanath Doley and Samiran Das, "Role of Dust Charge in the Formation of Higher Order Weakly Relativiatic Dust Ion-Acoustic Solitary Waves in Dusty Plasma", International conference on 'Imerging Role of Mathematics in Science and Technology' 24-26 October 2024, Department of Mathematics, Jawaharlal Nehru College, Boko, Guwahati, Assam.

30. Afruza Begum and Samiran Das, "An investigation on the effects of classroom learning environment towards the performance of secondary level students’ in the subject mathematics ", International conference on 'Imerging Role of Mathematics in Science and Technology' 24-26 October 2024, Department of Mathematics, Jawaharlal Nehru College, Boko, Guwahati, Assam.

31. Imdad Ali and Samiran Das, "Role of self-concept and motivation in algebraic problem-solving achievement among secondary school students in Morigaon district of Assam", International conference on 'Imerging Role of Mathematics in Science and Technology' 24-26 October 2024, Department of Mathematics, Jawaharlal Nehru College, Boko, Guwahati, Assam.

 

Reviewer of many prestigious journals such as

  • Physics of Plasmas (AIP)

  • IEEE Transactions on Plasma Science (IEEE)

  • Journal of Korean Physical Society (Springer Nature)

  • Journal of Physics: Conference Series (JPCS) (IOP Publishing)

etc.

Delivered a talk on “Importance and Applications of Ordinary Differential Equation” on 6th August, 2021 at Bridge Course programme under TEQIP III project during 5th-9th August, 2019 at Bineswar Brahma Engineering College, Kokrajhar, Assam invited by Assam Science and Technology University.

  1. Local Coordinator of the STTP "Effective Implementation of Teaching-Learning System", January 21-25, 2013 at CIT Kokrajhar.

  2. Local Coordinator of the STTP "Learning Management System (through ICT)", March 5-9, 2019 at CIT Kokrajhar.

  3. Local Coordinator of the STTP "Managing Yourself (through ICT)", March 18-22, 2019 at CIT Kokrajhar.

  4. Co-Convener of the workshop "Advancement in Instrumentation and Signal Processing", Nov 15-19, 2019 at CIT Kokrajhar.

  5. Member of the organizing committee of the workshop "Career Opportunities in Animation Design", 7th August 2020 at CIT Kokrajhar.

  6. Member of the organizing committee of the workshop "Role of Mathematics in the Rural Development under NEP-2020", 6th September 2020 at CIT Kokrajhar.

  7. Convener of the workshop "Future Prospect on Plasma Research", 8th June 2023 at CIT Kokrajhar.

  1. “4th Orientation Programme”, 01-12-2010 to 28-12-2010 at UGC- Academic Staff College, University of North Bengal, Darjeeling, WB.

  2. ‘Refresher course in Mathematics and Statistics’, 16-06-2012 to 04-08-2012 at UGC- Academic Staff College, Himachal Pradesh University, Shimla, Himachal Pradesh.

  3. ‘Subject Refresher Course in Teacher Education II’, 21-08-2021 to 04-09-2021 at UGC HRDC Aligarh Muslim University, Aligarh, UP.

  4. ‘Improving Teaching Competency for 21st Century Learners’, 19-12-2011 to 30-12-2011 at NITTTR Kolkata, WB.

  5. ‘Computational and Experimental aspects in Thermal Science’, 27-02-2012 to 02-03-2012 at NERIST Itanagar, Arunachal Pradesh.

  6. ‘Nanofabrication Technologies’, 28-09-2012 to 29-09-2012 organised by IIT Guwahati & IISc Bangalore at IIT Guwahati.

  7. ‘Effective Implementation of Teaching-Learning System’, 21-01-2013 to 25-01-2013 organised by NITTTR Kolkata at CIT Kokrajhar (Assam).

  8. Workshop on ‘Recent Trends in Mathematical Sciences’, 18-02-2013 to 24-02-2013 at Bodoland University, Kokrajhar (Assam).

  9. ‘Theory of Internet and Webpage Design’, 21-07-2014 to 25-07-2014 at NITTTR Kolkata.

  10. ‘Recent Advances on Applied Mathematics’, 20-09-2014 to 21-09-2014 at NIT Agartala.

  11. ‘Mathematics Teaching: Pedagogy and Practice’, 20-02-2015 to 22-02-2015 at CET, IIT Guwahati (Assam).

  12. ‘Fundamentals of Environmental Pollution’, 13-07-2015 to 17-07-2015 at NITTTR Kolkata, Guwahati Extension Centre.

  13. ‘Mathematical Analysis and its Application to Engineering’, 02-01-2016 to 04-01- 2016 at IIT Guwahati.

  14. ‘Publishing Connect Workshop’, 05-03-2016 Organized by Elsevier at Gauhati University, Guwahati (Assam).

  15. ‘Mathematical and Technical writing using LaTex’, 16-12-2016 to 30-12-2016 at NITTTR Kolkata.

  16. ‘Author Workshop’, 21-11-2017 organised by Elsevier in collaboration with Central Library, CIT Kokrajhar.

  17. ‘Optimization Techniques with Engineering Applications’, 29-01-2018 to 02-02-2018 at NITTTR Chandigarh.

  18. ‘5th ISI workshop on Pattern Analysis and Applications (PAA)’, 05-02-2018 to 08-02-2018 Organized by CVPRU, ISI Kolkata at CIT Kokrajhar.

  19. ‘Problem Based Learning’, 25-06-2018 to 29-06-2018 at NITTTR Kolkata.

  20. ‘Induction Training’, 16-07-2018 to 20-07-2018 at NITTTR Kolkata.

  21. ‘Wireless and Mobile Communication’, 03-12-2018 to 07-12-2018 at NKN course organized by IIT Guwahati at CIT Kokrajhar.

  22. ‘Evaluating Students’ Performance and Designing Question Papers’, 25-02-2019 to 01-03-2019 at NITTTR Kolkata.

  23. ‘Learning Management System’, 05-03-2019 to 09-03-2019 at NITTTR Chandigarh.

  24. ‘Managing Yourself’, 18-03-2019 to 22-03-2019 at NITTTR Chandigarh.

  25. ‘Research Seminar Day cum Springer-Nature Author Workshop’, 04-04-2019 at CIT Kokrajhar

  26. ‘The Future of Batteries’, 29-05-2020 organised by BrightTalk, online.

  27. ‘Career Opportunities in Animation Design’, 07-08-2020 organised by Deptt of MCD, CIT Kokrajhar.

  28. ‘Role of Mathematics in the Rural Development under New Education Policy of India 2020’, 06-09-2020 at Deptt of Mathematics, CIT Kokrajhar.

  29. ‘Computational Tools and Techniques for Engineers’, 08-20 February 2021 at NITTTR Chandigarh.

  30. ‘Fractional Dynamical Systems’, 26-06-2021, Dept. of Mathematics, Bannari Amman Institute of Technology, Sathyamangalam, Tamil Nadu.

  31. ‘Challenges of Higher Education in N.E. India’, 05-10 July 2021, E&ICT Academy, IIT Guwahati.

  32. ‘Digital Tools for Writing, Authoring and Reviewing Manuscripts’, 12-23 July 2021’ E&ICT Academies IIT Guwahati, NIT Patna, MNIT Jaipur, IIT Kanpur, IIITDM Jabalpur & IIT Roorkee.

  33. ‘Environmental Engineering Laboratory: Equipment and Procedure’, 26-07-2021 to 06-08-2021, NITTTR Kolkata.

  34. ‘Curriculum Development and Implementation’, 13-09-2021 to 17-09-2021’ NITTTR Kolkata.

  35. ‘Drinking water purification technologies’, 20-09-2021 to 01-10-2021, NITTTR Kolkata.

  36. ‘Impact Lecture Series’, 22-09-2021 (Session I) and 07-10-2021(Session II), NIT Silchar.

  37. ‘International Workshop on Numerical and Analytical Techniques in Engineering Problems-2022’, 19-01-2022 to 21-01-2022, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu, India.

  38. ‘Digital Pedagogy and Tools for Teaching and Learning’, 23-05-2022 to 27-05-2022, NITTTR Kolkata.

  39. ‘Academic Research Writing and LaTeX’, 13-06-2022 to 24-06-2022, NITTTR Kolkata

  40. ‘Role of Machine Learning in Cosmology’, 10-07-2022’ School of Computer Science and Engineering (SCOPE) and the School of Advanced Sciences (SAS), VIT-AP University.

  41. ‘Strategies and Solutions for Boosting Mathematics Learning’, 27-08-2022, ST. Xavier’s Institute of Education (autonomous) Mumbai- 400020.

  42. ‘Advanced Pedagogy’, 31-10-2022 to 11-11-2022, NITTTR Kolkata.