Browsing by Author "Pritam Das"

Now showing 1 - 4 of 4

A case of rapidly progressive dementia: A diagnosis not to be missed
(Blackwell Publishing Ltd, 2019) Pritam Das; Saumya Gupta; Ishan Kumar; Indrajeet Singh Gambhir; Sankha Shubhra Chakrabarti
[No abstract available]
Insights from the analytical solution of a periodically driven transverse-field Ising chain
(American Physical Society, 2025) Pritam Das; Anirban Dutta
We derive an exact analytical expression, at stroboscopic intervals, for the time-dependent wave function of a class of integrable quantum many-body systems, driven by the periodic delta-kick protocol. To investigate long-time dynamics, we use the wave function to obtain an exact analytical expression for the expectation values of the defect density, magnetization, residual energy, fidelity, and the correlation function after nth drive cycle. Periodically driven integrable closed quantum systems absorb energy, and the long-time universal dynamics are described by the periodic generalized Gibbs ensemble (GGE). We demonstrate that the expectation values of all observables are divided into two parts: one highly oscillatory term that depends on the drive cycle n, and the rest of the terms are independent of it. Typically, the n-independent part constitutes the saturation at large n and periodic GGE. The contribution from the highly oscillatory term vanishes in large n. We also generalize our formalism to include square-pulse and sinusoidal driving protocols. © 2025 American Physical Society.
L-type calcium channel blockers and a symptom complex mimicking de Melo-Souza’s syndrome
(Springer-Verlag Italia s.r.l., 2019) Upinder Kaur; Pritam Das; Indrajeet Singh Gambhir; Sankha Shubhra Chakrabarti
[No abstract available]
Morvan’s syndrome—is a pathogen behind the curtain?
(Springer-Verlag Italia s.r.l., 2018) Rohit Singh; Pritam Das; Upinder Kaur; Anamika Misra; Ashis Choudhury; Sukdev Manna; Rohit Gaude; Deepak Gautam; Indrajeet Singh Gambhir; Sankha Shubhra Chakrabarti
Morvan’s syndrome is a rare syndrome of likely autoimmune etiology characterized by peripheral nerve hyperexcitability, dysautonomia, insomnia, and fluctuating delirium with prominent hallucinations. Since its first mention in 1890, less than 100 cases have been described in literature. The largest existing review includes details of 29 cases. This case series describes 4 cases (M = 4) of Morvan’s syndrome which presented between May and November 2017 to a single tertiary care referral teaching hospital in north India. All the four patients manifested behavioral abnormalities, sleep disturbances, hallucinations, autonomic dysfunction, and clinical signs of peripheral nerve hyperexcitability, mostly as myokymia. Two of the patients had Anti-CASPR2 (contactin-associated protein 2) antibodies. Three of them had electromyography features of peripheral nerve hyperexcitability and only one had elevated cerebrospinal fluid protein level. We hypothesize that Morvan’s syndrome and other less characterized autoimmune encephalitis/peripheral nervous system syndromes may have infectious triggers. A possible viral trigger may result in generation of autoantibodies which result in the typical manifestations. We base these hypotheses on the finding of four cases of an orphan disease within a short period of time in a limited geographical distribution. © 2018, Springer-Verlag Italia S.r.l., part of Springer Nature.