Dr. Satyabrata Sahoo

EDUCATIONAL ATTAINMENTS:

Ph.D. in Physics (August,1995) from Jadavpur University under the supervision of  Prof. T.K.Mitra, Dept. of Theo. Phys.,Indian Association for the Cultivation of Science, Jadavpur, Calcutta, India.
THESIS:  A Critical Study of Bipolaronic States.

M.Sc. in Physics (1987) with 1st class from University of Calcutta.
SPECIALIZATION: Solid State Physics.

B.Sc. in Physics (1985) with 1st class  from University of Calcutta.
Minors: Mathematics, Chemistry.  

ACCOMPLISHMENT:  Junior Research Fellowship and Senior Research Fellowship of C.S.I.R. (Council of Scientific and Industrial Research), INDIA. 

POSTDOCTORAL RESEARCH :

Research Associate in Indian association for the Cultivation of Science, Jadavpur, Kolkata-75, INDIA(August 1995- July 1997).

Research Associate in Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan 106, R.O.C. (April’ 1999- August’2000).

Visiting Scientist in Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan 106, R.O.C. (June’ 2001- July’2001).

Visiting Scientist in Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan 106, R.O.C. (June’ 2002- August’2002).

Visiting Scientist in Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan 106, R.O.C. (October’ 2005- December’2005).

Visiting Scientist in Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan 106, R.O.C. (August’ 2008- September’2008).

PRESENT STATUS: Principal,Dhruba Chand Halder College, Dakshin Barasat, South 24 Parganas,W.B.,INDIA

Teaching Experience-18 years
Area of specialization: CONDENSED MATTER PHYSICS
Title of Thesis: A CRITICAL STUDY OF BIPOLARONIC STATES

RESEARCH ACOMPLISHMENT:

a) Computational Biophysics

Several Statistical and mathematical analysis have been performed on the biological DNA sequences. The study of molecular evolution and different measures of biological sequence similarity and the statistics of sequence comparison have been performed. A number of algorithms have been developed for sequence comparison and finding tRNAs. Nonrandom amino acid sequences in proteins have also been studied in order to understand gene regulation. Compositional complexity such as homopolymers and short period sequence repeats have also been investigated to study the molecular structure and dynamics of these sequences 

b) Condensed matter Physics & Computational nanophysics

A numerical technique namely, Complex Absorbing Potential Method has been developed to study the resonating states of the quantum dots in polar semiconductor,

A theoretical study on the ground and the excited state properties of quantum dots in polar semiconductor is done systematically.

c) Computational Atomic Physics

An alternative approach (Complex Absorbing Potential Method) to study the resonating state for the many-electron atomic system has been developed and has been applied to hydrogen, Lithium and Sodium.

Research Project completed:

The DNA Sequence Analysis for Gene Identification: A Minor Research project approved by UGC (PSW-060/05-06(ERO) dated 21/3/2006).

In Silico Detection of Potential tRNA Genes and tRNA-like Structures in Genomic DNA Sequences: A Minor Research Project approved by UGC (PSW-056/11-12(ERO) dated 20/10.2010).

Ph.D. Thesis guided:

Computational Approaches For Gene Expression And Identification Of Highly Expressed   Genes in Diverse Genomes: A Comparative Analysis by Shibsankar Das

awarded Ph. D. (Sc.) degree at Jadavpur University.

RESEARCH PLAN:

The Study of Impurity States in Low Dimensional Heterostructure

Project Summary:
      With the recent advancement in nanofabrication technology, it has now been possible to manufacture low dimensional nanostructure such as two dimensional quantum wells,extremely thin quantum wires, and even zero dimensional quantum dots of artificial semiconductor microcrystal. The physical phenomenon associated to the impurity states in such low dimensional heterostructures is an important aspect of physics. Moreover, the knowledge of these states has fundamental as well as technical importance. As of now, most of the low-dimensional nanostructures are  made of  ionic or polar crystals. So, the interaction of electron(hole) with the longitudinal phonons is an important mechanism which can strongly influence the impurity states as well as the physical properties of the low dimensional heterostructures in polar crystals. The polarons (bipolarons) may be the possible candidate to explain the observed physical properties (e.g. conductivity, optical absorption spectra etc.)of  these  low dimensional heterostructures. This research project primarily deals with the study of polaron/bipolaron states in a low dimensional heterostructures. With an objective of this project to understand the physics behind the physical phenomenon associated to the impurity states in mesoscopic system,we are investigating the role of polaron or bipolaron on the physical properties of low dimensional heterostructures in polar crystals. This is very much necessary to improve the nanodevice technology.
   We have carried out an extensive study of model potentials for various complex systems with an objective to develop a suitable model potential  for the description of polaron in a low dimensional heterostructures.

      The net outcome of this work is going to enhance our understanding of  low dimensional microsrystals which have potential application in nano device technology.

THE DNA SEQUENCE  ANALYSIS FOR GENE IDENTIFICATION

 Project Summary:

         During the past few years, there has been intense discussion about the existence, the nature and the origin of the correlations in DNA sequences. Different techniques have been used for the analysis, Despite the continuing debate on different methods on rather struggling questions, it is now well admitted that certain kind of correlation do exist in genomic sequences and it is not just an artifact of the non uniformity in the composition of genes. But, their biological interpretation still remains a continuing debate and furthermore, it  is still an open question whether the correlation properties are different for protein-coding and non-coding regions of nucleotide sequence and how they can be related to the expression and regulation of genes.
      This research project mainly deals with the study of nucleotide base correlations in Genomic DNA sequences.  The major part of the project will comprise of developing a suitable mathematical model to find the existence , the nature and the origin of any correlation in DNA sequences.
     With an objective   to find the existence ,the nature and the origin of any correlation in a DNA sequence and thus, to understand the nucleotide structure of the coding region in a genomic DNA sequences which is believed to contain vast information of our life cycle, an extensive investigation is being carried out to develop a computational approach to search for a characteristic function which will behave differently(with  the hypothesis that  nucleotide base structure  and correlation  is different  for coding and  non-coding regions) in coding and  non-coding regions of the Genomic DNA sequences. Recently,we have attempted to devise an expression measure of a gene from relative codon  bias(RCB). There are number of measures currently in use that quantify codon usage in genes. Based on the hypothesis that gene expressivity and codon composition is strongly correlated, RCB has been defined to provide an intuitively meaningful measure of an extent of  the codon preference in  a gene. We have developed a simple approach to assess the strength of RCB(RCBS) in genes as a guide to their likely expression level and illustrate this with an analysis of Escherichia Coli and Yeast genomes. Our efforts to quantitatively predict gene expression levels in Escherichia Coli  and Yeast met with high level of success. Surprisingly, we observe a strong correlation between RCBS and protein length indicating natural selection in favour of shorter genes to be expressed at higher level.The agreement of our result with high protein abundances, micro array data and radioactive data demonstrates that genomic expression profile available in our method can be applied in a meaningful way to the study of cell physiology and also for more detailed studies of particular gene of interest.
       Finally, we aim to develop an algorithm on the basis of the previous analysis to annotate the Gene in a Genomic DNA sequence.

THE STUDY OF tRNA ISODECODER GENES

PROJECT SUMMARY:
      tRNAs are  the key components in amino-acid synthesis , their uses are expanding exponentially with time , including in the specialized areas of design of drugs.All tRNAs are characterized by a secondary structure made up of three hairpin loops and a terminal helical stem(cloverleaf) which fold into an L-shaped  tertiary structure. The main functional regions in tRNA are the anticodon triplets which read the messenger RNA(mRNA)codons and the 3’ CCA nucleotides where an amino acid cognate  to the tRNA is attached. Codon degeneracy for the 20 amino acids requires  tRNAs with distinct anticodons(tRNA isoaccepterors) to read codons for each amino acid. There are 21 isoacceptor families, one for each amino acid and one for seleno-cysteine. An isoacceptor family may consist of one or more tRNA members.tRNA isoacceptors have been the main targets for biological, biochemichal and computational studies of tRNA function. The abundance of tRNA isoacceptors correlates with the codon usage of highly abundant proteins.But a number of studies have revealed that the number of tRNA species is greater than the total number of isoacceptors. In these cases ,it is found that the number of tRNA genes have  the same anticodon but different sequences elsewhere in the tRNA body. These are called tRNA isodecoder genes. Furthermore, the fraction of tRNA isodecoder genes among all tRNA genes increases across the phylogenetic spectrum. The phylogenetic relationship of tRNA  isodecoder genes suggests that some may perform unique functions in organisms belonging to same phylogenetic branch. Few efforts have been devoted to study the potential functions of tRNA isodecoders. The benefit of having a collection of tRNA isodecoders in translation is not very clear till now and the unique role of tRNA isodecoders is yet to be determined. As the database of tRNA sequences expanded, algorithms to annotate tRNAs became available .Presently two powerful software are used for tRNA annotation . These are tRNAscan-SE  and ARAGORN .These softwares are being used to locate and identify tRNAs in the newly sequenced genomes . Up until recently the split tRNAs remained outside the reach of the two above-mentioned  software . At present the new version of ARAGORN annotates  the split tRNAs .We have observed the deficiencies in the above two software . Many archaeal and eukaroytic  tRNAs  contain introns . Most of these introns are at canonical position , i.e., between 37 and 38 of  tRNA .These are the canonical introns . Though the length of the canonical intron is somewhat arbitrary , they are fairly easily accounted for by the present software .  The difficulty arises for noncanonical introns . These are  introns located at position other than canonical . These are of arbitrary length . Detecting these are difficult , sometimes beyond the capabilities of the existing software . As we looked closely over the archaeal domain we found many non-annotated  tRNAs .  This continues to be a major challenge.
       There are a few things that are known generally about tRNA introns . These relate to the exon-intron boundaries . The secondary structure at the boundary is the bulge-helix-bulge(BHB) .Looking carefully over this BHB one quickly discovers many variations on the so-called standard BHB. Most of the canonical-intron-exon boundaries have the standard  two-fold- axis-symmetric BHB . It is important to emphasize that even for canonical- intron-exon boundaries there are variations about this standard motif . The splice-site is on the bulges of the BHB . For the noncanonical-intron-exon boundaries the variations- on- the-standard become the rule . The BHB may not be quite symmetric . This led us to put forward  the alternate intron splicing ansatz . Suffice to say the present tRNA-annotating softwares  falls woefully short when noncanonical introns appear in tDNA sequences .In course of running the project, we feel to develop an algorithm to annotate tRNA genes
        As of now  we are at advanced stages of development of a software which takes  care of canonical and noncanonical introns . The bulge-helix-bulge motif at the exon-intron boundaries are checked , the splice sites identified , the anticodon marked . Currently we are fixing a  few remaining bugs and glitches . Some tRNAs are believed  to appear in halves . A generalized split-tRNA software is currently under advanced stage of development in our laboratory .The results we have generated using these software give us the  confidence that these  are useful and contemporary .
      The objectives of this project is  to detect and quantify relative amounts of  tRNA isodecoders in different speces and to understand their roles in the life cycle.
  During the past few years, there has been intense discussion about the existence,and the nature of the diversity in tRNA  genes(tRNA isodecoders). Different techniques have been used for the analysis. Due to the continuing debate on different methods on rather struggling questions, it is now well admitted that certain kind of correlation do exist between the diversity of tRNA genes and the life cycle and it is not just an artifact of the non uniformity in the composition of genes. But, their biological interpretation still remains a continuing debate and furthermore, it  is still an open question whether the tRNA isodecoders are harmful or useful in translation and can be related to the expression and regulation of genes.
      We are carrying out an extensive study of isodecoder genes for different species.The entire research work is being divided  into two parts: a) Collection of Raw data ,and  b) Theoretical analysis. In the first step we gather data towards the construction of the database of tRNA of different species  to study their individual characteristics and unique features.  The major part of the project is to classify different varieties of tRNA e.g.,(1)tRNA-gene that are simple , containing no introns,(2) tRNAs-genes that have canonical introns   ;(3) tRNA-genes with noncanonical intron.(4) Special and exotic  tRNA-genes , such as the ones with stop-anticodons and  construct the data base for isoacceptor families.
      Finally, we will analyse the base nucleotide structure of the tRNAs by an extensive study and will develop an algorithm to identify the isodecoder genes.

DETERMINATION OF RESONANCE ENERGY AND WIDTHS BY COMPLEX  ABSORBING POTENTIAL METHOD

The theoretical developments in the resonance scattering theory during the last few years have gained considerable impetus due to its increasing importance in various areas of atomic and chemical physics. Specifically , the resonant scattering theory has led to simple models for many collisional  processes which are of great importance in many laboratory, atmospheric and astrophysical environments.
          The computation of scattering wavefunctions is a very difficult task because of their non L2 nature. An L2 approximation to a resonance state can be obtained by diagonalization of the Hamiltonian after it has been projected onto an L2 basis set. The Feshbach projection techniques, the stabilization method , the complex coordinate rotation method etc. are the big steps forward in the development of  purely  L2 method to determine resonance energy and width.
            Parallel to these developments in the computation of resonances using  L2 techniques, Complex absorbing potential(CAP) method comes out to have the great advantage over the other existing methods and motivate us to extend the method to the treatment of the complex atoms and molecules.
             The CAP method consists of the introduction of the complex absorbing potential to the physical Hamiltonian leading to an effective Hamiltonian. We have employed CAP method to a model potential to establish the method as a viable computational procedure to compute the energy of the resonance states. The agreement with the exact results gives us confidence in our numerical results. We, then, step forward to apply this method in the Stark problem.Our results  in hydrogen atom are convincingly good in comparison with those obtained by other existing methods. Our interest lies in developing new computational technique in the area of resonance calculation for the many electron systems to produce fruitful results in atomic collision process. So far, there has not been exhaustive study of stark effect in Li atom due to computational difficulties of the exsisting techniques when applied to non hydrogen system. We have predicted interesting results for Li and also studied the evolution of resonances in parallel electric and magnetic field. The application of this method to larger system is always possible and is in progress.

COMPLEX COORDINATE ROTATION METHOD
TO STUDY THE PHOTOIONIZATION CROSS SECTION OF ATOMS IN PLASMA ENVIRONMENT

         The study of atomic processes in plasma has gained considerable interest over the past few decades. Generally, plasma is short lived and exits in a state very far from thermal equilibrium. Thus, a detailed understanding of various atomic processes is essential for an adequate description of large number of phenomena associated with  diverse field of astrophysical plasmas, rare gas lasers , fusion plasmas etc.  The plasma environment can be expected to significantly influence various atomic processes primarily through the screening of the long range electrostatic interaction of charged particles.
        The photoionization  process is the subject of special attention in plasma physics because it is extremely sensitive to the details of atomic structure and the correlation effects between atomic electrons.  The cross sections of photoionization  for atoms in dense plasma are likely to be different from those of free atoms due to  screening effect of the surrounding plasma ions .
       The calculation of photoionisation cross section involves sums and integrals which go over all optically bound and continuum atomic states..In principle, the cross section for photoionization can be calculated when accurate wave functions are known for the states of the target atom. The difficulties associated with replacing the continuum integral by a finite sum over square integrable(L2) basis sets have been discussed by earlier authors. There have been a number of studies suggesting that the conventional bound state techniques may be successfully employed to calculate the photoionization cross section of atoms and molecules. It has been known for some time that the Complex –coordinate rotation method[28] can successfully be applied to the calculation of photoionization cross sections.
           We have developed a computational scheme  to investigate the influence of plasma environment on photoionization of atoms and ionized atoms within the framework of the method of complex coordinate rotation.  In this approach, the atomic system is considered to be composed of  an atomic ion core and the valence electron. Irrespective of the structure of the ion core, the interaction between the valence electron and the core is represented by a model potential Vm(r).  The basic idea of model potential is to simulate the multielectron core interaction with the single valence electron in an analytical modification of the Coulomb potential. The use of model potential, which includes the average effect of the passive electrons, not only provides a much simpler way to study the multielectron systems, but is also useful in understanding the physical interpretation of the phenomenon in which a reduced number of electrons are involved.
      A number of studies have been done to investigate the  influence of plasma on the photoionization of  hydrogen, helium, lithium and sodium atoms. These studies reveal that strong screening remarkably alters the photoionization cross section over a considerable range of photon energy, but the influence of plasma is considerably reduced for the energetic photon in case of weak screening. The plasma screening effect is found to uncover a Cooper minimum in the photoionizing transitions from the ground state of Li in Debye plasma environment. Furthermore, the Cooper minimum, which appears close to the threshold for an isolated Na atom, shifts toward the higher energy region as the plasma screening increases.The appearance of a Cooper minimum in the photoionization cross section of Li in plasma environment is of special interest, since it profoundly affects the  shape of the cross sections , i.e., the spectral distribution of oscillator strength. Accordingly, the theoretical investigation of photoionization process from excited  helium is worthwhile. Helium is both abundant element in the universe and has been the subject of many laboratory experiments. The photoionization from excited states of helium has proved to be an important one, not only for its own sake but as a device for studying the theory and calculation of free bound transition probabilities, as a stimulus for other studies of photodetachment, and as an important contributor to the radiative properties of the sun, and other stars and of plasmas. Further studies on the other non-hydrogenic ions are in progress.
      Our calculations have shown that photoionization is very sensitive in the plasma environment near the ionization threshold. In our approach towards the calculation of photoionization cross section, the charged particle interaction potential is obtained by the static Debye-Hückle model. The static screening formula obtained by Debye-Hückle model overestimates the plasma screening effect on the photoionization cross section in dense plasma for low excitation energy. It is, indeed, necessary to recalculate the photoionization cross section in dense plasma on the basis of kinetic plasma theory, which, in particular, permits to account the collective plasma effects, namely, dynamic screening along with plasma fluctuation. However, we emphasize that plasma’s influence on collision events by means of a model potential turns out to be efficient in determining the characteristic plasma response on photoionization cross section.

LIST OF PUBLICATION

[45] Satyabrata Sahoo and Shibsankar Das,Analyzing Gene Expression and Codon Usage Bias in Metallosphaera Sedula,J. Bioinf. Intell. Control 3, 72-80 (2014)

[44]Satyabrata Sahoo and  Shibsankar Das; Analysing gene expression and codon usage bias in diverse genomes using a variety of models;2014, Current Bioinformatics 9(5),102-112.

[43]Smarjit Das, Sanga Mitra, Satyabrata Sahoo and Jayprokas Chakrabarti; Viral/Plasmid captures in Crenarchaea; 2014, Journal of Biomolecular Structure and Dynamics, 32(4),546-554.

[42] Shibsankar Das, Uttam Roymondal, Brajadulal Chottopadhyay, Satyabrata Sahoo; Gene expression profile of the cynobacterium synechocystis genome;2012, Gene 497,344.

[41] Sanga Mitra, Smarjit Das,Satyabrata Sahoo, Chandana Sinha and Jayprakash Chakrabarti; Phylogeny derived from homodimeric endonucleage correlates with its pre-RNA substrates;2011, Adv. Biosc. and Biotech. 2,117

[40] Smarjit Das, Sanga Mitra, Satyabrata Sahoo, and Jayprakash Chakrabarti; Novel Hybrid Encodes both Continuous and Split tRNA Genes;2011, J.Bio. Struc. & Dynm. 28,1

[39]Smarjit Das, Ritwik Mukherjee, Satyabrata Sahoo, Rachna Thakkar and Jayprakash Chakrabarti; Structural Clones of UAG Decoding RNA;2009, J.Bio. Struc. & Dynm. 27,1

[38] Satyabrata Sahoo and Y.K.Ho; On the appearance of a Cooper minimum in the photoionization cross sections of the plasma-embedded Li atom; 2010,JQSRT.111,52.

[37] Satyabrata Sahoo and Y.K.Ho;Photoionization of the excited He* atom in Debye plasma; 2009, Research letters in Physics. 832413,1.

[36] Partha Sarathi Das and Satyabrata Sahoo; Bipolaronic excita -tions of interacting electron (hole)gas in one dimensional lattice model; 2009,Physica B,404,4225.
[35] Shibsankar Das, Uttam Roymondal ,  and Satyabrata Sahoo; Analyzing gene expression from relative codon usage bias in Yeast genome : a statistical significance and biological relevance:2009,Gene 443,121.
[34] Uttam Roymondal , Shibskar Das,  and Satyabrata Sahoo; Predicting Gene Expression Level from Relative Codon Usage Bias : An Application to Escherichia Coli  Genome:2009, DNA Research 16,13.

[33]S.Sahoo and Y.C.Lin and Y.K.Ho;2008,Quantum confined hydrogenic impurity in a spherical quantum dot under the influence of parallel electric and magnetic field:Physica E40,3107.

[32]S.Sahoo and Y.K.Ho:2006,Photoionization of Li and Na in Debye plasma environments:Physics of Plasmas 13,1,2006.

[31]I.Mukhopadhyaya,A.Som,S.Sahoo:Word organization
in Coding DNA :a mathematical model:2006,Theory in Biosciences 125,1

[30] J.Chakrabarty, Z. Ghosh, B. Mallick,S. Das, S. Sahoo and H.  Singh:2006, tRNA- isoleucine-tryptophan composite gene: BBRC 339,37.

[29] J.Chakrabarty,B.Mallick,,S.Sahoo,Z.Ghosh,S.Das; 2005, Identity elements  in Archeal tRNA;DNA Research 12,235

[28]S.Sahoo and Y.K.Ho;2005, Field induced energy shifts and widths of low lying states of Na atom in Parallel Magnetic and Electric Fields. : Chin J. Phys 43,58

[27] S. Das, J. Chakrabarti, Z. Ghosh, S. Sahoo and B. Mallick ; A new measure to study phylogenetic relations in the brown algal order, Ectocarpales : The Codon Impact Parameter ;2005, Journal of Biosciences, 30(5) 101-111. 

[26]J.Chakrabarti, S.Sahoo, B.Mallick S. Das and Z. Ghosh: 2005, Algorithm for pattern recognition in nano-sized archaea, Indian J. Phys.(2005), 79(6), 559-562.

[25]S.Sahoo and Y.K.Ho;2004,Anomalous stark effect in the ground state of the confined hydrogen atom in a spherical quantum dot: Phy. Rev. B  69, 165323

[24] A.Som, S.Sahoo and I. Mukhopadhyay and J. Chakrabarti; 2003,Scaling Violations in coding   DNA. ; European Physical Letters 62,271.

[23]A.Som,S.Sahoo and J.Chakrabarti;2003,Coding DNA equences: Statistical Distributions; Mathematical Biosciences183,49.

[22]S.Chattopadhyay, S.Sahoo, W.A.Kanner and J. Chakrabarti;2003, Pressures in Archeal Protein Coding Genes: A Comparative Study:Comparative and Functional Genomics 4,56.

[21]S.Sahoo and Y.K.Ho;2002, Resonances of Hydrogen and Lithium Atoms in Parallel Magnetic and Electric Fields : Phys.Rev. A 65,15403

[20]S.Sahoo and Y.K.Ho;2000, Determination of Resonance  Energy and Width Using th Method of Complex Absorbing Potential:Chin. J. Phys.  38,127.

[19]S.Sahoo and Y.K.Ho;2000, Complex Absorbing Potential Method to Study the Stark Effect in  Hydrogen and Lithium :J.Phys.B.33,2195.

[18]S.Sahoo and Y.K.Ho;2000, Stark Effect on the Low-lying Excited States of the Hydrogen and the Lithium Atoms: J.Phys.B. 33,5151.

[17]S.Chattopadhyay,A.Som,S.Sahoo and J.Chakrabarti ;2000,Order and Fluctuation in DNA sequences:Indian J.Phys.74B, 1.

[16] S.Tarafdar, P.Nandy, A.Som, S.Sahooand J.Chakrabarti and N.Nandy;1999, Self-similarity and scaling exponent for DNA walk in two and four dimensions;Indian J.Phys73B(2),337.

[15]S.Sahoo,A.Bandyopadhyay,T.K.Mitra and N.C.Sil; 1999, The ground state energy of the Helium isoelectronic series;Indian J. Phys.73B(1), 25.

[14]A.Bandyopadhyay,S.Sahoo and N.C.Sil;1999, The calculation of the ground state energy of the Positronium negative ion Ps; Indian. J.Phys.
73B(2),337.                                   

[13]S.Sahoo;1999, Formation of the ground and the excited states of the Frohlich bipolaron; Phy. Rev. B60, 10803.

[12]S.Sahoo;1998,Energy levels of the Frohlich polaron in a spherical quantum dot; Phys. Lett. A238,390.

[11]S.Sahoo;1998,The strong coupling polaron in reduced dimensionality;J.Phys.C10,1999.

[10]S.Sahoo;1996,The ground state description of Frohlich polaron in symmetric quantum dot  within the framework of LLP-H approach;Z.Phys.B101,97.

[9]S.Sahoo,1996, On the formation and stability of the Frohlich bipolaron in two and three dimensional system;Nuovo Cimento D18,849.

[8]S.Sahoo, A.Bandyopadhyay, T.K.Mitra and N.C.Sil ; 1996,Helium atom revisited;Indian J.Phys. 70B, 93

[7]S.Sahoo;1995, The regular perturbation theory on the stability of the strong coupling bipolaron;Journal of Phys. C7,4457.
    
[6]S.Sahoo;1994, A variational calculation on the stability of two centre Frohlich bipolaron; Phys.Lett.A195.

[5]S.Sahoo and T.K.Mitra;1994, On the formation of an optical mode induced single centre bipolaron;Journal of Phys. Soc. of Japan 63,4102. 

[4]S.Sahoo and T.K.Mitra; 1993, Molecular Orbital approach to the Frohlich bipolaron; Phys. Rev. B48,6019.

[3]S.Sahoo and T.K.Mitra;1993, Canonical transformation, perturbation theory and strong coupling Landau-Pekar polaron revisited;Indian J. Phys.67A, 303.

[2]S.Sahoo and T.K.Mitra;1993, Molecular orbital bipolarons and oxide superconductors, Indian J. Phys. 67A, 425.

[1]S.Sahoo and T.K.Mitra;1992,Bipolaron formation in polar solids; Indian J .physics, 66A, 277.

PARTICIPATION IN CONFERENCES, SYMPOSIA, WORKSHOP ETC.

1. Participated in UGC sponsored National Seminar on’Quantum Information: Theory and Computer Science’ organized by Department of mathematics, Jogesh Chandra Choudhury College, Kolkata  in collaboration with Netaji Nagar Day College, Kolkata on 14th -15th February,2012.
2. Participated in ‘An Indo-Singapore Joint Workshop: Role of computational biology in advancing modern medicine’, organized by Centre of Applied mathematics and Computational Science SINP, Kolkata on 2nd-3rd Feb,2012
3. Participated in UGC sponsored National Seminar on’The Physics behind Electronics/Optoelectronics and their applications’ organized by Department of Physics, Sammilani Mahavidyalaya, Kolkata  in collaboration with Cetre for Pedagogical studies in Mathematics, Kolkata on 1st  and 2nd Dec,2011.
4. Participated in UGC sponsored National Seminar on’Cocepts and challenges in Astronomy and Astrophysics’organized by Department of Physics, Sunderban Mahavidyalaya, Kakdwip, South 24 Parganas in collaboration with M.P.Birla Institute of Fundamental Research, Kolkata on 24th 25th Nov,2011 .
5. Participated in the “Fourth Workshop on genetic Epidemiological methods for Discussion on Complex human Traits” held on February 23-28,2009 ,organized by TCG-ISI Centre for Population Genomics, Kolkata, India and Univ. of Pittsburgh,USA.
6. Paper  Presented: Hybrid tRNA gene: A bridge between continuous and split tRNAs,2010, EMBO/EMBL Sympsosium:Non-Coding Genome,p-113, organized by EMBL, Heidelberg, held in, Heidelberg, Germany,13-16 Oct,2010.
7. Paper presented: Annotation of putative pyrolysine tRNAs:Correlation with in-frame usage of amber codon UAG; S.Das, S.Sahoo, R. Mukherjee and J. Chakrabarti,2007, 22nd  International tRNA Workshop, p-75, held in Upsala, Sweden, November 1-6,2007.
8.  Paper presented: Identity determinants for AARS and intron splicing endonucleases; B. Mallik, Z. Ghosh, J. Chakrabarti, S.Das, and S.Sahoo, 2007,International Conference on Chromosomes to Neurons(ICCTN),p37, organized by Dept. of Biophysics, Molecular Biology & Genetics, University of Calcutta and SINP, Kolkata,.held on January 12-14,2007.
9. Paper presented: New Proline-tRNA gene in Methanococcus jannaschii.; Z. Ghosh, B. Mallik,J. Chakrabarti, S.Das, and S.Sahoo, 2007,International Conference on Chromosomes to Neurons(ICCTN),p58, organized by Dept. of Biophysics, Molecular Biology & Genetics, University of Calcutta and SINP, Kolkata,.held on January 12-14,2007.
10. Paper presented: Substrate identities for tRNA-splicing-Endonucleases and AARS in Eukaryotes; B. Mallik, Z. Ghosh,J. Chakrabarti, S.Das, and S.Sahoo, 2006,International Conference on Bioinformatics-2006(InCoB 2006),p232, .held on December 18-20,2006.
11. Paper presented: tRNAs of nonstandard amino acids in Sulfolobus acidocaldarious.; Z. Ghosh, B. Mallik,J. Chakrabarti, S.Das, and S.Sahoo, 2006,International Conference on Bioinformatics-2006(InCoB 2006),p422, .held on December 18-20,2006.
12. Paper presented: tRNA-scape in archaea; Sahoo, S., Mallick, B., Ghosh, Z., Das, S. and Chakrabarti, J. (2005). 21st International tRNA Workshop, p-168, organized by IISc., Bangalore, held on December 2-7,2005.
13. Paper presented: Non-canonical introns in tRNA genes of archaea; J. Chakrabarti , B.Mallick, Z.Ghosh, S.Sahoo, and S. Das, (2004). 2nd RNA Group meeting, Dec 21-22,2004,organized by Biophysics Division ,Saha Institute of Nuclear Physics, Calcutta.
14.  Paper presented: Distribution of Palindromic sSequences in Lambda; Z. Ghosh, S.Sahoo, G. Purokayastha, J. Chakrabarti,(2004), in the symposium on ‘Bioinformatics For Genome Analysis’, organized by Bose Institute, Calcutta during January 29-30,2004.
15.  Participated  in the ‘Workshop on Statistical Computational    Genomics’, organized by Indian Statistical Institute , Calcutta during December 11-20,2001.
16.  Participated in XIIIth  national conference on ‘Atomic and Molecular Physics’ held in Indian Association for the Cultivation of Science, from January 16-20,2001. Contributed paper entitled, ‘ Complex Absorbing Potential Method to find the Resonance in Hydrogen Atom in External Magnetic field.
17.  Participated in the International conference on ‘Few Body Problem in Physics’ held in National Taiwan University, Taipei, Taiwan, from 6-10 March, 2000. Presented Poster entitled, ‘ Complex Absorbing Potential Method to study the Stark effect in Hydrogen and Lithium’.
18.  Participated in national Symposium-cum-workshop on trends in ‘Bioinformatics’ organized by Bose Institute, from March 24-27, 1998. Poster presented entitled’ Scaling exponent in a DNA walk model and implications for coding and non-coding region’.
19.  Participated in national conference on ‘Theoretical physics today’ organized by Indian Association for the Cultivation of Science from April 22-24, 1998. Posters presented entitled, (i) Self-similarity and scaling exponent for DNA walk in two and four dimensions, (ii) The calculation of the ground state energy of the positronium negative ion Ps.
20. Participated in School on Complex Systems, organized by Indian Association for the Cultivation of Science from January 30-February 2, 1995.
21.  Participated in SERC School, Puri, 23rd Jannuary-12th February, 1994.
22.  Participated in the workshop on Electronic Structures of Random Alloys, organized by S.N.Bose National Centre for Basic Sciences from November 20-December 5, 1990.  

Refresher and Orientation Course

w.Participated in UGC sponsored Refresher Course in Physics organized by Academic Staff College, University of Calcutta, from November 06-November 25,2006.

x. Participated in UGC sponsored Refresher Course in Physics organized by Academic Staff College, University of Calcutta, from July 08-July 28,2005.

y. Participated in UGC sponsored Orientation Programme in Physics organized by Academic Staff College, University of Calcutta, from August 30-September 27,2001.