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Article ; Online: Multidimensional electronic spectroscopy in high-definition-Combining spectral, temporal, and spatial resolutions.

Tiwari, Vivek

2021 Volume 154, Issue 23, Page(s) 230901

Abstract: Over the past two decades, coherent multidimensional spectroscopies have been implemented across the terahertz, infrared, visible, and ultraviolet regions of the electromagnetic spectrum. A combination of coherent excitation of several resonances with ... ...

Abstract	Over the past two decades, coherent multidimensional spectroscopies have been implemented across the terahertz, infrared, visible, and ultraviolet regions of the electromagnetic spectrum. A combination of coherent excitation of several resonances with few-cycle pulses, and spectral decongestion along multiple spectral dimensions, has enabled new insights into wide ranging molecular scale phenomena, such as energy and charge delocalization in natural and artificial light-harvesting systems, hydrogen bonding dynamics in monolayers, and strong light-matter couplings in Fabry-Pérot cavities. However, measurements on ensembles have implied signal averaging over relevant details, such as morphological and energetic inhomogeneity, which are not rephased by the Fourier transform. Recent extension of these spectroscopies to provide diffraction-limited spatial resolution, while maintaining temporal and spectral information, has been exciting and has paved a way to address several challenging questions by going beyond ensemble averaging. The aim of this Perspective is to discuss the technological developments that have eventually enabled spatially resolved multidimensional electronic spectroscopies and highlight some of the very recent findings already made possible by introducing spatial resolution in a powerful spectroscopic tool.
Language	English
Publishing date	2021-06-29
Publishing country	United States
Document type	Journal Article
ZDB-ID	3113-6
ISSN	1089-7690 ; 0021-9606
ISSN (online)	1089-7690
ISSN	0021-9606
DOI	10.1063/5.0052234
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Article ; Online: Surgical microdiscectomy versus transforaminal epidural steroid injection in patients with sciatica due to lumbar disc herniation.

Tiwari, Vivek

The Lancet. Rheumatology

2021 Volume 3, Issue 11, Page(s) e750

Language	English
Publishing date	2021-10-28
Publishing country	England
Document type	Letter
ISSN	2665-9913
ISSN (online)	2665-9913
DOI	10.1016/S2665-9913(21)00278-2
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Article ; Online: Letter to the Editor: "Comparison of early post-operative complications following unilateral or single-stage bilateral unicompartmental knee arthroplasty".

Tiwari, Vivek

The Knee

2021 Volume 29, Page(s) 589–590

MeSH term(s)	Arthroplasty, Replacement, Knee/adverse effects ; Humans ; Knee Joint/diagnostic imaging ; Knee Joint/surgery ; Osteoarthritis, Knee/surgery ; Postoperative Complications/etiology
Language	English
Publishing date	2021-03-01
Publishing country	Netherlands
Document type	Letter ; Comment
ZDB-ID	1200476-5
ISSN	1873-5800 ; 0968-0160
ISSN (online)	1873-5800
ISSN	0968-0160
DOI	10.1016/j.knee.2021.02.013
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Article ; Online: Vibrations That Do Not Promote Vibronic Coupling Can Dominate Observed Lineshapes in Two-Dimensional Electronic Spectroscopy.

Sahu, Amitav / Tiwari, Vivek

The journal of physical chemistry letters

2023 Volume 14, Issue 19, Page(s) 4617–4624

Abstract: Impulsively generated wavepackets can report on vibronic couplings underlying ultrafast electronic relaxation. Coherence maps (CMs) in multidimensional spectroscopy resolve beating amplitudes of such wavepackets as two-dimensional contour maps. A precise ...

Abstract	Impulsively generated wavepackets can report on vibronic couplings underlying ultrafast electronic relaxation. Coherence maps (CMs) in multidimensional spectroscopy resolve beating amplitudes of such wavepackets as two-dimensional contour maps. A precise understanding of how these wavepackets manifest spectroscopically is vital for unambiguously deciphering their mechanistic significance and establishing CMs as a powerful tool for guiding the synthetic design of functional vibronic couplings. Here we take a step in this direction. We establish physically distinct origins of recently reported apparent similarities between diagonal node-like CM lineshapes in bacteriochlorophyll monomers and multichromophoric photosynthetic reaction centers (RCs). The former arise when vibrational wavepackets survive on both ground and excited electronic states, while nodal lines in RCs arise when vibrational wavepackets that do not participate in energy transfer are coherently transferred to the acceptor. We resolve recent spectroscopic observations and illustrate new mechanistic insights gained by connecting microscopic interference between electronic relaxation pathways and observed CMs.
Language	English
Publishing date	2023-05-12
Publishing country	United States
Document type	Journal Article
ISSN	1948-7185
ISSN (online)	1948-7185
DOI	10.1021/acs.jpclett.3c00753
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Article ; Online: Vibronic resonance along effective modes mediates selective energy transfer in excitonically coupled aggregates.

Patra, Sanjoy / Tiwari, Vivek

The Journal of chemical physics

2022 Volume 156, Issue 18, Page(s) 184115

Abstract: We recently proposed effective normal modes for excitonically coupled aggregates that exactly transform the energy transfer Hamiltonian into a sum of one-dimensional Hamiltonians along the effective normal modes. Identifying physically meaningful ... ...

Abstract	We recently proposed effective normal modes for excitonically coupled aggregates that exactly transform the energy transfer Hamiltonian into a sum of one-dimensional Hamiltonians along the effective normal modes. Identifying physically meaningful vibrational motions that maximally promote vibronic mixing suggested an interesting possibility of leveraging vibrational-electronic resonance for mediating selective energy transfer. Here, we expand on the effective mode approach, elucidating its iterative nature for successively larger aggregates, and extend the idea of mediated energy transfer to larger aggregates. We show that energy transfer between electronically uncoupled but vibronically resonant donor-acceptor sites does not depend on the intermediate site energy or the number of intermediate sites. The intermediate sites simply mediate electronic coupling such that vibronic coupling along specific promoter modes leads to direct donor-acceptor energy transfer, bypassing any intermediate uphill energy transfer steps. We show that the interplay between the electronic Hamiltonian and the effective mode transformation partitions the linear vibronic coupling along specific promoter modes to dictate the selectivity of mediated energy transfer with a vital role of interference between vibronic couplings and multi-particle basis states. Our results suggest a general design principle for enhancing energy transfer through synergistic effects of vibronic resonance and weak mediated electronic coupling, where both effects individually do not promote efficient energy transfer. The effective mode approach proposed here paves a facile route toward four-wavemixing spectroscopy simulations of larger aggregates without severely approximating resonant vibronic coupling.
Language	English
Publishing date	2022-05-13
Publishing country	United States
Document type	Journal Article
ZDB-ID	3113-6
ISSN	1089-7690 ; 0021-9606
ISSN (online)	1089-7690
ISSN	0021-9606
DOI	10.1063/5.0088855
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Article: Total Elbow Arthroplasty from Indian Perspective: A Systematic Review.

Tiwari, Vivek / Dwidmuthe, Samir

Indian journal of orthopaedics

2022 Volume 56, Issue 12, Page(s) 2029–2041

Abstract: Background: Total elbow arthroplasty (TEA) provides satisfactory pain relief and restores elbow range of motion and function in patients with end-stage arthritis. Due to advances in implant design and surgical techniques, the indications for surgery ... ...

Abstract	Background: Total elbow arthroplasty (TEA) provides satisfactory pain relief and restores elbow range of motion and function in patients with end-stage arthritis. Due to advances in implant design and surgical techniques, the indications for surgery have expanded to include various other conditions affecting the elbow. The previous studies and systematic reviews reported satisfactory mid-term and long-term clinical outcomes after TEA with relatively stable complication and revision rates. However, there is lack of information in the literature about the results of TEA in Indian patients. Methods: Two reviewers performed a comprehensive literature search using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in three online databases-Pubmed/MEDLINE, Google scholar and the Cochrane database for clinical trials. Only original studies published in the English literature reporting outcomes of primary TEA in Indian patients were included for analysis. Using pre-defined inclusion and exclusion criteria, articles were screened and the relevant articles identified. Data were extracted with the primary objective to assess pain relief and functional outcome after TEA in Indian patients, and secondary objective to identify indications for surgery, complication rates and incidence of implant removals. Results: A total of 212 TEAs (210 patients) from ten articles were included in this systematic review. All the TEAs were done using Baksi's semi-constrained sloppy-hinged elbow prosthesis. The most common indication of TEA was post-traumatic sequelae (124 elbows, 58.5%), followed by comminuted intra-articular fracture distal humerus (53 elbows, 25%). At a weighted mean follow-up of 7.5 years, 80.7% cases had complete pain relief. The weighted mean flexion, extension restriction, supination and pronation were 122.6°, 20.8°, 57.3°, and 48.6°; respectively. The weighted mean Mayo Elbow Performance Score was 92.1 points with excellent outcome. Overall, a total of 68 complications were reported (32%) and the implants needed to be removed in 14 elbows (6.6%) including two revisions. Conclusions: This systematic review found that the functional outcome and pain relief obtained with TEA using Baksi's sloppy-hinged prosthesis in Indian patients were satisfactory overall. The complication rates and implant removal rates were lower than those reported with other patient populations.
Language	English
Publishing date	2022-09-24
Publishing country	Switzerland
Document type	Journal Article ; Review
ZDB-ID	603194-8
ISSN	0019-5413
ISSN	0019-5413
DOI	10.1007/s43465-022-00744-y
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Article ; Online: Rapid scan white light two-dimensional electronic spectroscopy with 100 kHz shot-to-shot detection.

Thomas, Asha S / Bhat, Vivek N / Tiwari, Vivek

The Journal of chemical physics

2023 Volume 159, Issue 24

Abstract: We demonstrate an approach to two-dimensional electronic spectroscopy (2DES) that combines the benefits of shot-to-shot detection at high-repetition rates with the simplicity of a broadband white light continuum input and conventional optical elements to ...

Abstract	We demonstrate an approach to two-dimensional electronic spectroscopy (2DES) that combines the benefits of shot-to-shot detection at high-repetition rates with the simplicity of a broadband white light continuum input and conventional optical elements to generate phase-locked pump pulse pairs. We demonstrate this through mutual synchronization between the laser repetition rate, the acousto-optical deflector, the pump delay stage, and the CCD line camera, which allows for rapid scanning of pump optical delay synchronously with the laser repetition rate, while the delay stage is moved at a constant velocity. The resulting shot-to-shot detection scheme is repetition rate scalable and only limited by the CCD line rate and the maximum stage velocity. Using this approach, we demonstrate the measurement of an averaged 2DES absorptive spectrum in as much as 1.2 s of continuous sample exposure per 2D spectrum. We achieve a signal-to-noise ratio of 6.8 for optical densities down to 0.05 with 11.6 s of averaging at 100 kHz laser repetition rate. Combining rapid scanning of mechanical delay lines with shot-to-shot detection as demonstrated here provides a viable alternative to acousto-optic pulse shaping approaches that is repetition-rate scalable, has comparable throughput and sensitivity, and minimizes sample exposure per 2D spectrum with promising micro-spectroscopy applications.
Language	English
Publishing date	2023-12-29
Publishing country	United States
Document type	Journal Article
ZDB-ID	3113-6
ISSN	1089-7690 ; 0021-9606
ISSN (online)	1089-7690
ISSN	0021-9606
DOI	10.1063/5.0179474
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Article: A Rare Case of Large Osteochondral Fracture of Patella.

Agrawal, Udit / Tiwari, Vivek / Selvanayagam, Rajkumar

Cureus

2023 Volume 15, Issue 7, Page(s) e41245

Abstract: Osteochondral fractures of the patella are relatively common pediatric knee injuries, often missed during the initial evaluation, and almost always associated with acute patella dislocations. We report the case of an adolescent patient with a very large ... ...

Abstract	Osteochondral fractures of the patella are relatively common pediatric knee injuries, often missed during the initial evaluation, and almost always associated with acute patella dislocations. We report the case of an adolescent patient with a very large osteochondral fracture of the patella involving almost the whole of the medial patellar facet and without concomitant dislocation of the patella. A 16-year-old adolescent presented to the emergency with pain and swelling in the left knee after sustaining a road traffic accident. On evaluation with an X-ray and a CT scan, a large osteochondral fracture of the patella was diagnosed. The fracture was treated with open reduction and internal fixation with headless compression screws after performing medial parapatellar arthrotomy. After two years, the patient recovered with a full and painless range of movement of the knee, with the complete radiological union of the fracture. This case report discusses a rare case of an adolescent with a large osteochondral fracture of the patella without concomitant patella dislocation.
Language	English
Publishing date	2023-07-01
Publishing country	United States
Document type	Case Reports
ZDB-ID	2747273-5
ISSN	2168-8184
ISSN	2168-8184
DOI	10.7759/cureus.41245
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Article ; Online: Low- and high-frequency vibrations synergistically enhance singlet exciton fission through robust vibronic resonances.

Bhattacharyya, Atandrita / Sahu, Amitav / Patra, Sanjoy / Tiwari, Vivek

Proceedings of the National Academy of Sciences of the United States of America

2023 Volume 120, Issue 49, Page(s) e2310124120

Abstract: Singlet exciton fission (SEF) is initiated by ultrafast internal conversion of a singlet exciton into a correlated triplet pair [Formula: see text]. The "reaction coordinates" for ultrafast SEF even in archetypal systems such as pentacene thin film ... ...

Abstract	Singlet exciton fission (SEF) is initiated by ultrafast internal conversion of a singlet exciton into a correlated triplet pair [Formula: see text]. The "reaction coordinates" for ultrafast SEF even in archetypal systems such as pentacene thin film remain unclear. Couplings between fast electrons and slow nuclei are ubiquitous across a range of phenomena in chemistry. Accordingly, spectroscopic detection of vibrational coherences in the [Formula: see text] photoproduct motivated investigations into a possible role of vibronic coupling, akin to that reported in several photosynthetic proteins. However, acenes are very different from chlorophylls with 10× larger vibrational displacements upon photoexcitation and low-frequency vibrations modulating intermolecular orbital overlaps. Whether (and if so how) these unique features carry any mechanistic significance for SEF remains a poorly understood question. Accordingly, synthetic design of new molecules aiming to mimic this process across the solar spectrum has broadly relied on tuning electronic couplings. We address this gap and identify previously unrecognized synergistic interplay of vibrations, which in striking contrast to photosynthesis, vitally enhances SEF across a broad, nonselective and, therefore, unavoidable range of vibrational frequencies. We argue that attaching mechanistic significance to spectroscopically observed prominent quantum beats is misleading. Instead, we show that vibronic mixing leads to anisotropic quantum beats and propose readily implementable polarization-based two-dimensional electronic spectroscopy experiments which uniquely distinguish vibrations which drive vibronic mixing and promote SEF, against spectator vibrations simply accompanying ultrafast internal conversion. Our findings introduce crucial ingredients in synthetic design of SEF materials and spectroscopy experiments aiming to decipher mechanistic details from quantum beats.
Language	English
Publishing date	2023-11-29
Publishing country	United States
Document type	Journal Article
ZDB-ID	209104-5
ISSN	1091-6490 ; 0027-8424
ISSN (online)	1091-6490
ISSN	0027-8424
DOI	10.1073/pnas.2310124120
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Book ; Online: Machine Learning Classification of Alzheimer's Disease Stages Using Cerebrospinal Fluid Biomarkers Alone

Tiwari, Vivek Kumar / Indic, Premananda / Tabassum, Shawana

2024

Abstract: Early diagnosis of Alzheimer's disease is a challenge because the existing methodologies do not identify the patients in their preclinical stage, which can last up to a decade prior to the onset of clinical symptoms. Several research studies demonstrate ... ...

Abstract	Early diagnosis of Alzheimer's disease is a challenge because the existing methodologies do not identify the patients in their preclinical stage, which can last up to a decade prior to the onset of clinical symptoms. Several research studies demonstrate the potential of cerebrospinal fluid biomarkers, amyloid beta 1-42, T-tau, and P-tau, in early diagnosis of Alzheimer's disease stages. In this work, we used machine learning models to classify different stages of Alzheimer's disease based on the cerebrospinal fluid biomarker levels alone. An electronic health record of patients from the National Alzheimer's Coordinating Centre database was analyzed and the patients were subdivided based on mini-mental state scores and clinical dementia ratings. Statistical and correlation analyses were performed to identify significant differences between the Alzheimer's stages. Afterward, machine learning classifiers including K-Nearest Neighbors, Ensemble Boosted Tree, Ensemble Bagged Tree, Support Vector Machine, Logistic Regression, and Naive Bayes classifiers were employed to classify the Alzheimer's disease stages. The results demonstrate that Ensemble Boosted Tree (84.4%) and Logistic Regression (73.4%) provide the highest accuracy for binary classification, while Ensemble Bagged Tree (75.4%) demonstrates better accuracy for multiclassification. The findings from this research are expected to help clinicians in making an informed decision regarding the early diagnosis of Alzheimer's from the cerebrospinal fluid biomarkers alone, monitoring of the disease progression, and implementation of appropriate intervention measures.
Keywords	Computer Science - Machine Learning ; Quantitative Biology - Quantitative Methods ; Statistics - Applications
Subject code	006 ; 610
Publishing date	2024-01-01
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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