IISER Pune Digital Repository

A repository of scholarly research output from the Indian Institute of Science Education and Research (IISER) Pune.

Browse publications, theses, and other research output produced by the IISER Pune community.

Email: libraryservices@iiserpune.ac.in

Communities in Digital Repository

Select a community to browse its collections.

Now showing 1 - 3 of 3

OTHER RESOURCES 604
PUBLICATIONS & PATENTS 7245
THESES & PROJECT REPORTS 3006
Theses submitted to IISER Pune in partial fulfilment of the requirements of the BS-MS dual degree, MSc. and Ph.D programmes. Also, project reports submitted by the students.

Recent Submissions

Access status: Open Access ,
Molecular Dynamics Simulations Study of Phase Behavior and Interfacial Structure in the Benzene–Methanol Azeotrope
(2026-09) JOSHI, PARTH; MUKHERJEE, ARNAB; Dept. of Chemistry; 20212009
Azeotropes are liquid mixtures that exhibit constant boiling behavior and behave as single substances during phase change, posing significant challenges in separation processes while playing important roles in chemical manufacturing and purification. Understanding the molecular origins of azeotropic behavior is therefore essential for the design of efficient separation strategies. In this study, molecular dynamics (MD) simulations were employed to investigate the microscopic behavior of the benzene-methanol azeotrope and its liquid-vapor interface over a range of temperatures and compositions. The reliability of the employed force field was first assessed by calculating fundamental thermophysical properties, including liquid density and enthalpy of vaporization, for the pure components as well as the azeotropic mixture. The simulated values show excellent agreement with experimental data, demonstrating the suitability of the force field for describing the system. The liquid-vapor interfacial analysis reveals that benzene exhibits preferential evaporation at lower benzene concentrations, whereas methanol becomes relatively more volatile at higher benzene concentrations. Furthermore, at the azeotropic composition and temperature, both benzene and methanol attain nearly equal compositions at the liquid-vapor interface, indicating that the volatilities of the two components become comparable. This molecular-level observation provides a microscopic explanation for the simultaneous boil- ing of both components, which is the defining characteristic of azeotropic behavior. Overall, this study demonstrates that molecular dynamics simulations can successfully capture the interfacial structure, molecular organization, and phase coexistence characteristics of the benzene-methanol azeotrope, providing valuable insight into the molecular mecha- nisms governing azeotropic mixtures.
Access status: Embargo ,
Shining Light Through the Dark: Observational Signatures of Exotic Astrophysical Dark Objects
(2026-09) SINGH BHANDARI, LALIT; THALAPILLIL, ARUN M.; Dept. of Physics; 20203770
The precise nature of dark matter remains one of the most profound unresolved questions in fundamental physics. While traditional searches have primarily targeted microscopic, weakly interacting particle candidates, the persistent absence of direct detection motivates a broader exploration of macroscopic, structured dark configurations. This thesis investigates the theoretical frameworks and observational signatures of a class of Exotic Astrophysical Dark Objects (EADOs), focusing on astrophysical Q-balls, mini-boson stars, primordial magnetic black holes (MBHs), and millicharged dark matter plasma environments around black holes. We first establish the theoretical viability of astrophysical Q-balls by deriving the conditions required for their existence, gravitational stability, and non-gravitational self-consistency. These conditions define the allowed Lagrangian parameter space in which Q-balls can remain stable macroscopic dark objects rather than collapsing gravitationally. Building on this framework, we analyze their gravitational lensing signatures. In the photometric regime, we analyze the distinctive microlensing signatures caused by extended thin-wall and beyond-thin-wall density profiles, showing how finite-size structure modifies the caustic-crossing behavior relative to idealized point-mass lenses. Using legacy microlensing data from EROS-2, OGLE-IV, and HSC-Subaru, we constrain astrophysical Q-balls in the range $10^{-7}\text{--}10^{-2}\,M_\odot$ to constitute no more than approximately $1\%$ of the total dark matter abundance. Extending this analysis to the high-precision astrometric regime, we study the centroid shifts generated by thin-wall Q-balls and mini-boson stars. We demonstrate that astrometric microlensing provides a substantially enlarged discovery volume relative to photometric searches, since the astrometric signal decays as $\theta_{\text{\tiny S}}^{-1}$ rather than $\theta_{\text{\tiny S}}^{-4}$. We identify caustic-induced centroid jumps as a distinctive kinematic signature of extended lenses. Using Gaia DR3-based projections, we forecast optimal event yields of order $6000$ astrometric microlensing events over a 10-year observation window and derive 90\% confidence-level exclusion limits over the mass range $10^{-1}\text{--}10^{7}\,M_\odot$ and physical radii up to $10^6\,\mathrm{AU}$. In the intermediate stellar-mass regime, these bounds can constrain the fractional dark matter abundance to $f_{\text{\tiny L}}\lesssim 10^{-3}$. We subsequently probe the dark sector through electromagnetic and strong-gravity phenomena. For primordial magnetic black holes, we show that extremal magnetic charges $Q_{\text{\tiny BH}}\gtrsim 10^{22}\,\mathrm{A~m}$, corresponding to masses $M_{\text{\tiny BH}}\gtrsim 10^{-6}\,M_\odot$, can generate Faraday rotation measures within current observational sensitivity. We also identify a topological polarization discriminator: unlike standard astrophysical dipoles, which yield a positive spatial polarization measure, the unbroken axial symmetry of an MBH enforces a null measure, providing a characteristic polarization signature for primordial magnetic monopoles. We further investigate the influence of millicharged dark matter plasmas on black hole shadows. By solving the modified electromagnetic dispersion relations in these plasma environments, we show that the physical photon sphere expands while the apparent shadow radius contracts. For physically viable sub-eV millicharged particles, this refractive contraction can reach approximately $25\%$ for a uniform density profile and can approach complete shadow suppression under radial accretion. These results establish black hole shadow measurements as a potential probe of macroscopic dark plasma environments. Finally, we analyze the tidal response of thin-wall Q-balls. In the thin-wall limit, these configurations obey the volume scaling $M_{\text{\tiny Q}}\propto R_{\text{\tiny Q}}^3$ and remain highly diffuse, with compactness typically satisfying $\mathcal{C}_{\text{\tiny Q}}\lesssim 10^{-4}$. By simplifying the coupled metric-scalar perturbation equations in this limit, we derive analytical expressions for the exterior logarithmic derivative and the quadrupolar tidal Love number. We find that thin-wall Q-balls exhibit extreme tidal deformability, with $k_2\sim 10^{16}\text{--}10^{28}$ across the mass range $0.1\text{--}100\,M_\odot$, substantially exceeding the corresponding values for neutron stars and compact boson stars. Collectively, the theoretical derivations and observational forecasts presented in this thesis establish a unified, multi-wavelength, and multi-messenger strategy for identifying, distinguishing, and constraining macroscopic dark matter configurations through photometric, astrometric, electromagnetic, black-hole-shadow, and gravitational-wave observables.
Access status: Embargo ,
Storied Stones: Antiquarian Engagements with Pre-sultanate Architecture in Maharashtra
(2026-09) PATIL, DIGVIJAY SAYAJIRAO; SOHONI, PUSHKAR; Dept. of Humanities and Social Sciences; 20203741
This study is born of curiosity-driven research, both literally and literarily. It is guided by a set of curiosities ranging from some that are personal to others expressed by believing and non-believing individuals over the last nine centuries. These curiosities broadly concern the antiquity of pre-sultanate architectural remains at religious sites in Maharashtra. These remains, dating from around 300 BCE to 1300 CE, consist of rock-cut and structural shrines, sculptures, inscriptions, and archaeological mounds. Historians now attribute them to various dynasties that ruled the region. Yet until the 19th century, these once-mighty dynasties were virtually unknown to Marathi people, and the remains came to be interpreted differently from their original meanings. This study follows the lives, and particularly the paradoxical afterlives of these remains. By considering them as sites of antiquarian curiosity and historical remembrance, the study examines how meaning-making processes have unfolded around these religious sites over the last nine centuries. The thesis consists of eight chapters. The first opens with a 1981 newspaper debate, aiming to sensitise readers to how 21st-century Marathi people have inherited religious sites in the region. The second broadly introduces Maharashtra as a study region, the pre-sultanate architectural remains therein, and the associated antiquarian and mnemonic practices. The third, fourth, and fifth chapters review relatively worldly interactions of pre-colonial believers with the natural and built environments, inscriptions, and archaeological mounds, respectively. The sixth explores how the inscriptions likely contributed to the amnesia surrounding pre-sultanate dynasties. The seventh sketches a biography of the nomenclature of pre-sultanate temples as hemadpanti. The last chapter reviews the paradigmatic shift in understanding pre-sultanate architectural remains in the 19th and 20th centuries, reflecting on what has been gained and possibly lost in the process. Together, this thesis is an attempt to make sense of—even appreciate—the pre-sultanate built heritage at religious sites in Maharashtra, with the continuities and discontinuities within.
Access status: Open Access ,
Topics in Local Langlands Correspondence for GL2(Qp) : Galois Orbits of Newforms and Extensions of p -adic Representations
(2026-09) DAS, SRIJAN; BANERJEE, DEBARGHA; Dept. of Mathematics; 20213601
This thesis investigates questions arising from the arithmetic of modular forms, Galois representations, and the local Langlands correspondence. The first part studies the global arithmetic of modular forms through the Galois action on Hecke eigenforms, while the second part explores the local representation-theoretic aspects of the $p$-adic Langlands correspondence. In the first part, we establish a lower bound for the number of non-CM Galois orbits of newforms with non-trivial quadratic nebentypus for sufficiently large weights. Extending the work of Dieulefait, Pacetti, and Tsaknias in the trivial nebentypus setting, we analyze the restrictions imposed by the quadratic character on local inertial types and determine the number of admissible Galois orbits of such types. We further prove that Atkin-Li pseudo-eigenvalues are Galois equivariant and hence, up to a natural equivalence relation, define a global Galois invariant. Together with existence results for newforms having prescribed local behavior, these invariants yield a lower bound for the number of non-CM Galois orbits by counting compatible pairs of local-global invariants. Finally, computations in small weights show that this lower bound is not always attained, indicating that certain local equivalences are not realized globally by Galois conjugation over the coefficient field of the modular form. The second part of the thesis concerns the $p$-adic local Langlands correspondence. We compute extension groups in the category of duals of $p$-adic Banach space representations of $\mathrm{GL}_2(\mathbb{Q}_p)$. Focusing on representations arising from the $p$-adic local Langlands correspondence for generic Galois representations, we classify these extensions completely. These results are then applied to prove the vanishing of extensions between the dual $p$-adic Banach space representations attached to reducible Galois representations and supercuspidal Galois isotypic components of the $p$-adic etale cohomology of the finite-level Drinfeld spaces.
Access status: Embargo ,
Api5 and FGF2: A potential tumourigenic signalling
(2026-09) GOYAL, ANISHA; LAHIRI, MAYURIKA; Dept. of Biology; 20202004
Cell death and cell division equilibrium are crucial for maintaining tissue homeostasis in a multicellular organism. Apoptosis plays an essential role in preserving homeostasis and hence occurs in a coordinated manner. However, inhibition of apoptosis may lead to cancer. Apoptosis Inhibitor 5 (Api5), an anti-apoptotic protein, is upregulated in various cancers such as ovarian, bladder, cervical and lung. Studies have demonstrated that altered expression of Api5 transforms breast epithelial cells, but the mechanism involved was not well elucidated. Interestingly, our study revealed that Api5 OE increases FGF2 (Fibroblast Growth Factor 2) levels at the molecular level. Histopathological analysis also showed that protein levels of Api5 and FGF2 are upregulated in Indian breast cancer patients. We have studied the mechanistic details of the change in morphology, proliferation and polarity observed upon FGF2/FGFR1 deregulation in Api5 overexpression background. Deciphering the signalling mechanism underlying Api5-FGF2 mediated breast tumourigenesis revealed that PDK1/Akt and Ras/MAPK/ERK pathway regulated multiple transformation phenotypes. PDK1/Akt enhanced proliferation and altered morphology during initial stages, whereas Ras/MAPK/ERK regulated polarity disruption, proliferation, and reduced apoptosis during later stages of morphogenesis. In conclusion, this study provides insights into the signalling mechanism regulating the transformation phenotypes associated with Api5 overexpression in a non-malignant breast epithelial cells.