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Seaver C, Bowers C, Beidel D, Holt L, Ramakrishnan S. A game-based learning approach to sleep hygiene education: a pilot investigation. Front Digit Health 2024; 6:1334840. [PMID: 38680214 PMCID: PMC11045930 DOI: 10.3389/fdgth.2024.1334840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 03/22/2024] [Indexed: 05/01/2024] Open
Abstract
Introduction Sleep hygiene education (SHE) consists of environmental and behavioral practices primarily intended to reduce sleep problems. Currently considered ineffective as a stand-alone treatment, the manner in which the education is typically delivered may be ineffective for the acquisition of new knowledge. The purpose of this study was to determine if a more engaging teaching medium may improve the efficacy of sleep hygiene education. This study examined the use of game-based learning to teach SHE to individuals with sleep problems. Methods 35 participants played the SHE games for 30 days. Differences in pre- and post-state anxiety and sleep quality measures were examined. Results Participants had significant improvements in sleep quality and state anxiety after using the app for 30 days, although scores for the majority of patients remained elevated. Discussion This pilot investigation provides initial evidence for the efficacy of a game-based approach to SHE.
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Dupuis LL, Fisher BT, Sugalski AJ, Grimes A, Nuño M, Ramakrishnan S, Beauchemin MP, Robinson PD, Santesso N, Walsh A, Wrightson AR, Yu L, Parsons SK, Sung L. Clinical practice guideline-inconsistent management of fever and neutropenia in pediatric oncology: A Children's Oncology Group study. Pediatr Blood Cancer 2024; 71:e30880. [PMID: 38291716 PMCID: PMC10937100 DOI: 10.1002/pbc.30880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 12/29/2023] [Accepted: 01/10/2024] [Indexed: 02/01/2024]
Abstract
BACKGROUND The primary objective was to measure the proportion of episodes where care delivery was inconsistent with selected recommendations of a clinical practice guideline (CPG) on fever and neutropenia (FN) management. The influence of site size on CPG-inconsistent care delivery, and association between patient outcomes and CPG-inconsistent care were described. METHODS This retrospective, multicenter study included patients less than 21 years old with cancer who were at high risk of poor FN outcomes and were previously enrolled to a Children's Oncology Group (COG) study at participating National Cancer Institute Community Oncology Research Program (NCORP) institutions from January 2014 through December 2015. Patients were randomly selected for chart review by participating sites from a COG-generated list. Care delivered in each episode was adjudicated (CPG-consistent or CPG-inconsistent) against each of five selected recommendations. RESULTS A total of 107 patients from 22 sites, representing 157 FN episodes, were included. The most common CPG-inconsistent care delivered was omission of pulmonary computerized tomography in patients with persistent FN (60.3%). Of 74 episodes where assessment of four (episodes without persistent FN) or five (episodes with persistent FN) recommendations was possible, CPG-inconsistent care was delivered with respect to at least one recommendation in 63 (85%) episodes. Site size was not associated with CPG-inconsistent care delivery. No statistically significant association between CPG-inconsistent care and fever recurrence was observed. CONCLUSIONS In this cohort of pediatric patients at high risk of poor FN outcomes, CPG-inconsistent care was common. Opportunities to optimize resource stewardship by boosting supportive care CPG implementation are highlighted.
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Gayen AK, Singla R, Ramakrishnan S. Hyperbranched polymers: growing richer in flavours with time. Chem Commun (Camb) 2024; 60:1534-1545. [PMID: 38252017 DOI: 10.1039/d3cc05506j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
Hyperbranched polymers (HBPs) have been studied for over three decades now; yet several interesting aspects continue to draw the attention of researchers worldwide. This is because of the simplicity of synthesis, their unique globular structure, and the numerous peripherally located functional groups that can be utilised to impart a variety of attributes, such as core-shell amphiphilicity, Janus amphiphilicity, clickable polymeric scaffolds, multifunctional crosslinkers, etc. Several reviews have been written on HBPs with a focus on synthetic strategies, structural diversity, and their potential applications; in this short feature article, we have taken an alternate approach to highlight some of the unique structural features of HBPs and their influence on the properties of HBPs. We also discuss their versatility and adaptability for the generation of several interesting functional polymeric systems. In the latter half, we focus on the utilisation of HBPs as multifunctional scaffolds, that rely on the numerous peripheral terminal groups. We conclude by drawing a structuro-functional analogy between the range of peripherally functionalised HBPs and other analogous, but more complex, polymeric systems. We believe that this review will serve as a visual sounding board that would encourage the development of several other applications for this class of unique polymers.
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Rajaiah B, Abiramalatha T, Ramakrishnan S. LATCH Score: Bridging the Gap in the Observational Study: AUTHORS' REPLY. Indian Pediatr 2023; 60:500. [PMID: 37293918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
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Gayen AK, Perala SK, Schauenburg D, Weil T, Ramakrishnan S. Amphiphilic Polymer Hydrogel-supported Catalysts: Tuning the Accessibility to the Catalytic Site by Molecular Jacketing. Chem Asian J 2023:e202300143. [PMID: 37143435 DOI: 10.1002/asia.202300143] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/13/2023] [Accepted: 05/03/2023] [Indexed: 05/06/2023]
Abstract
Amphiphilic hydrogels, prepared using a peripherally clickable hyperbranched polyester (HBP) and PEG-diazides of different molecular weights, were used to ligate Cu utilizing the triazole rings formed by the alkyne-azide click reaction. Since only a fraction of the peripheral propargyl groups in the HB polyester are needed to generate the crosslinked polymer, the remaining were clicked with different types of azides, such as MPEG azide, decyl azide or 4-methylbenzyl azide, to create a molecular jacket around the catalytic sites that can potentially influence the catalytic activity and reaction outcome. The crosslinked films ligated with Cu functioned very effectively to catalyse alkyne-azide click reactions, both in water and in organic solvents; the nature of the molecular jacket around the catalytic site has a clear influence the reaction rate, which depended upon the relative solubilities of the reactants. The gel-supported catalysts films can be recycled multiple times with little loss in catalytic activity.
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Ramakrishnan S, Abbas A, Jordan N. Removal of breast implants as primary treatment for autoimmune/inflammatory syndrome induced by adjuvants. Scand J Rheumatol 2023; 52:219-220. [PMID: 36178439 DOI: 10.1080/03009742.2022.2114187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Sonia SVE, Nedunchezhian R, Ramakrishnan S, Kannammal KE. An empirical evaluation of benchmark machine learning classifiers for risk prediction of cardiovascular disease in diabetic males. INTERNATIONAL JOURNAL OF HEALTHCARE MANAGEMENT 2023. [DOI: 10.1080/20479700.2023.2170006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Ramalingam R, Patro K, Ramakrishnan S, Rangarajan D. Collateral circulation − “Hand of God:” Salvaging the transplant kidney! INDIAN JOURNAL OF TRANSPLANTATION 2023. [DOI: 10.4103/ijot.ijot_114_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
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Jana R, Ramakrishnan S. Counterion-Based Polymerizable Porogens─Direct Preparation of Nanoporous Polymer Matrices with Control over Pore Size and Carboxylic Acid Content. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c02154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Kotla S, Van Smaalen S, Ramakrishnan S, Rekis T, Bao J, Schaller A, Eisele C, De Boissieu M, De Laitre G, Noohinejad L. Incommensurately modulated Rb 2ZnCl 4. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022. [DOI: 10.1107/s2053273322091677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Agarwal H, Kotla S, Ramakrishnan S, Eisele C, Noohinejad L, Tolkiehn M, Bag B, Ramakrishnan S, Van Smaalen S. Incommensurately modulated charge-density wave phase transition in EuAl 2Ga 2. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022. [DOI: 10.1107/s2053273322091665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Van Smaalen S, Ramakrishnan S, Rohith Kotla S, Rekis T, Bao J, Eisele C, Agarwal H, Noohinejad L, Tolkiehn M, Paulmann C, Singh B, Verma R, Bag B, Kulkharni R, Thamizhavel A, Singh B, Ramakrishnan S. Charge-density waves in EuAl 4 and SrAl 4. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022. [DOI: 10.1107/s2053273322095481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Ramakrishnan S. TIFR at seventy-seven – in ceaseless pursuit of excellence. CURR SCI INDIA 2022. [DOI: 10.18520/cs/v123/i3/451-460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Shea L, Akhave N, Sutton L, Compton L, York C, Ramakrishnan S, Miller C, Wartman L, Chen D. 104 Loss of Kdm6a and Trp53 drives the development of squamous cell skin cancer in mice. J Invest Dermatol 2022. [DOI: 10.1016/j.jid.2022.05.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Bera A, Ganguly D, Ghorai SK, Rath JP, Ramakrishnan S, Kuriakose J, Amarnath S, Chattopadhyay S. Treatment of natural rubber with bio-based components: A green endeavor to diminish the silica agglomeration for tyre tread application. CHEMICAL ENGINEERING JOURNAL ADVANCES 2022. [DOI: 10.1016/j.ceja.2022.100349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Sasidharan D, G V, Ramakrishnan S. Muscle Fatigue Analysis by Visualization of Dynamic Surface EMG Signals Using Markov Transition Field. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2022; 2022:3611-3614. [PMID: 36086577 DOI: 10.1109/embc48229.2022.9871981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Muscle fatigue analysis is important in the diagnosis of neuromuscular diseases. Analysis of surface electromyography (sEMG) signals by non-linear probabilistic approach is useful in studying their transitions and thus the neuromuscular system. In this study, a method to visualize sEMG signals using Markov transition field (MTF) under fatigue conditions is proposed. sEMG signals are acquired from 45 healthy participants during biceps curl exercise. They are filtered and divided into ten equal segments. Markov transition matrix is constructed and corresponding MTF image is generated. The average self-transition probability is extracted and compared for both non-fatigue and fatigue segments. It is observed that the extracted feature shows high statistical significance with p value less than 0.001. The increase in average self-transition probability under fatigue condition correlates with the reduction in the degree of signal complexity. Thus, encoding of sEMG signals to images is helpful in analyzing the complexity of the neuromuscular system. Clinical Relevance- This approach may be helpful in analyzing muscle fatigue related with various myoneural conditions.
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Sharma V, Khuntia BK, Soneja M, Huddar VG, Ramakrishnan S, Sharma P, Rathore S, V V, Wadhawan M, Chhabra V, Agrawal A, Singh M, Kumar A, Nesari TM, Sharma G. Efficacy of add-on Ayurveda and Yoga intervention in health care workers of tertiary care hospital during COVID-19: Randomized controlled trial. Complement Ther Clin Pract 2022; 48:101601. [PMID: 35598547 PMCID: PMC9080705 DOI: 10.1016/j.ctcp.2022.101601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/02/2022] [Accepted: 05/05/2022] [Indexed: 11/23/2022]
Abstract
Background The present study aimed to evaluate the safety and prophylactic efficacy of add-on Comprehensive Ayurveda and mindfulness-based Yoga (CAY) regimen to standard care among HealthCare Workers (HCWs) against COVID-19. Materials and methods This prospective single-blind (outcome assessor-blinded) RCT was conducted in tertiary care hospital in Delhi during July 2020–April 2021. HCWs of both sexes were randomized to add-on CAY intervention or control group. The primary outcomes were the incidence of confirmed COVID-19 positive cases and influenza-like illness events (ILI). Secondary outcomes were anxiety (GAD-7), depression (PHQ-9), and quality of life (SF-36) at the end of 12 weeks. Results Three hundred fifty-six participants (181 in intervention and 175 in the control group) were randomized. With the modified intention to treat approach, we analyzed 309 participants. The mean age for the intervention and control group was 39.3 ± 10.1 and 36.6 ± 10 years, respectively. Incidence of COVID-19 event was higher in control group compared to CAY group (16 of 164 [9.8%] vs. 11 of 145 [7.6%]; P = 0.50). The incidence of ILI events was also higher in the control group as compared to the CAY group (14 of 164 [8.5%] vs 9 of 145 [6.2%]). The health change domain of the SF-36 questionnaire showed statistically significant improvement in the CAY group as compared to the control group (P < 0.01). Conclusion Incidence of COVID-19 and ILI events was lower in the CAY group compared with the contr ol group, though the difference is not statistically significant.
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Fernandez RK, Ramakrishnan S, Sukumaran TT, Kilarkaje N, Pillay M. A unique bilateral accessory forearm flexor muscle. Folia Morphol (Warsz) 2022; 82:407-411. [PMID: 35411546 DOI: 10.5603/fm.a2022.0037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/11/2022] [Accepted: 03/23/2022] [Indexed: 11/25/2022]
Abstract
Muscular and neurovascular variations in the upper extremity are of utmost clinical significance. Here we report a unique bilateral accessory muscle in the forearm and palm of an 89-year-old male cadaver. The accessory muscle presented two bellies on the right side, one in the forearm, innervated by the anterior interosseous nerve, and the other in the palm, innervated by a branch of the median nerve. A long tendon interconnected the two bellies. On the left side, the muscle had a single belly in the palm, which began at the end of a long tendon that extended from the forearm. However, on both sides, the muscle originated from the posterior surface of the flexor digitorum superficialis belly and inserted along with the first lumbrical muscle into the dorsal digital expansion of the index finger. The proximal parts of the variant muscles were sandwiched between the flexor digitorum muscles. The palmar bellies coursed distally through the carpal canal and lay deep to the superficial palmar arch, and superficial to the first lumbrical, between the thenar muscles and the lateral-most tendon of the flexor digitorum superficialis. Arguably, the accessory muscle might be a variant of a lumbrical muscle, as reported before, but innervation of the proximal belly by the anterior interosseous nerve suggests that the muscle may well be a deep accessory muscle at the forearm, probably appeared as a diverted part of the flexor digitorum profundus. Its space-occupying course through the forearm and palm, especially through the carpal canal, might be clinically significant as it might contribute to nerve compression pathologies in the upper extremity. This accessory muscle also indicates the complex nature of individual muscle formation and evolution of the upper extremity with constant changes in the morphology of muscles based on their changing functions.
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Fekri-Ershad S, Ramakrishnan S. Cervical cancer diagnosis based on modified uniform local ternary patterns and feed forward multilayer network optimized by genetic algorithm. Comput Biol Med 2022; 144:105392. [PMID: 35299043 DOI: 10.1016/j.compbiomed.2022.105392] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 03/02/2022] [Accepted: 03/08/2022] [Indexed: 11/29/2022]
Abstract
Cervical cancer is one of the most common types of cancer for women. Early and accurate diagnosis can save the patient's life. Pap smear testing is nowadays commonly used to diagnose cervical cancer. The type, structure and size of the cervical cells in pap smears images are major factors which are used by specialist doctors to diagnosis abnormality. Various image processing-based approaches have been proposed to acquire pap smear images and diagnose cervical cancer in pap smears images. Accuracy is usually the primary objective in evaluating the performance of these systems. In this paper, a two-stage method for pap smear image classification is presented. The aim of the first stage is to extract texture information of the cytoplasm and nucleolus jointly. For this purpose, the pap smear image is first segmented using the appropriate threshold. Then, a texture descriptor is proposed titled modified uniform local ternary patterns (MULTP), to describe the local textural features. Secondly, an optimized multi-layer feed-forward neural network is used to classify the pap smear images. The proposed deep neural network is optimized using genetic algorithm in terms of number of hidden layers and hidden nodes. In this respect, an innovative chromosome representation and cross-over process is proposed to handle these parameters. The performance of the proposed method is evaluated on the Herlev database and compared with many other efficient methods in this scope under the same validation conditions. The results show that the detection accuracy of the proposed method is higher than the compared methods. Insensitivity to image rotation is one of the major advantages of the proposed method. Results show that the proposed method has the capability to be used in online problems because of low run time. The proposed texture descriptor, MULTP is a general operator which can be used in many computer vision problems to describe texture properties of image. Also, the proposed optimization algorithm can be used in deep-networks to improve performance.
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Bag B, Loke R, Singh B, Thamizhavel A, Singh B, Ramakrishnan S. Superconductivity in Heusler compound ScAu 2Al. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:195403. [PMID: 35176733 DOI: 10.1088/1361-648x/ac5651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/17/2022] [Indexed: 06/14/2023]
Abstract
We report superconducting state properties and electronic structure of a full Heusler material ScAu2Al. The resistivity measurement indicates a zero-field (at nominal Earth's field) superconducting transition temperature,Tc= 5.12 K (in contrary to the previously reported value of 4.4 K), which falls in the highestTc-regime among the Heusler superconductors. The magnetization data shows that ScAu2Al is a moderate type-II superconductor, where the critical field values can be estimated from the Ginzburg-Landau-Abrikosov-Gorkov theory. The field-dependent magnetization response further shows signatures of flux jump in ScAu2Al. A sharp jump in the temperature dependent specific heat (Cp) data confirms bulk superconductivity. We report that the electron-phonon coupling constant,λe-ph= 0.77, suggesting a moderate electron-phonon coupling in ScAu2Al. Further, we show that the observedλe-phvalue in ScAu2Al is the highest amongst the reported Heusler superconductors, indicating strong correlation betweenTcandλe-phvalues and significant role of electron-phonon coupling in mediating superconductivity in Heusler superconductors. Finally, we discuss the electronic properties and reveal the existence of van Hove singularity near the Fermi level in ScAu2Al.
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Reifman J, Kumar K, Hartman L, Frock A, Doty TJ, Balkin TJ, Ramakrishnan S, Vital-Lopez FG. 2B-Alert Web 2.0, an Open-Access Tool for Predicting Alertness and Optimizing the Benefits of Caffeine: Utility Study. J Med Internet Res 2022; 24:e29595. [PMID: 35084336 PMCID: PMC8832274 DOI: 10.2196/29595] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 10/12/2021] [Accepted: 11/15/2021] [Indexed: 02/04/2023] Open
Abstract
Background One-third of the US population experiences sleep loss, with the potential to impair physical and cognitive performance, reduce productivity, and imperil safety during work and daily activities. Computer-based fatigue-management systems with the ability to predict the effects of sleep schedules on alertness and identify safe and effective caffeine interventions that maximize its stimulating benefits could help mitigate cognitive impairment due to limited sleep. To provide these capabilities to broad communities, we previously released 2B-Alert Web, a publicly available tool for predicting the average alertness level of a group of individuals as a function of time of day, sleep history, and caffeine consumption. Objective In this study, we aim to enhance the capability of the 2B-Alert Web tool by providing the means for it to automatically recommend safe and effective caffeine interventions (time and dose) that lead to optimal alertness levels at user-specified times under any sleep-loss condition. Methods We incorporated a recently developed caffeine-optimization algorithm into the predictive models of the original 2B-Alert Web tool, allowing the system to search for and identify viable caffeine interventions that result in user-specified alertness levels at desired times of the day. To assess the potential benefits of this new capability, we simulated four sleep-deprivation conditions (sustained operations, restricted sleep with morning or evening shift, and night shift with daytime sleep) and compared the alertness levels resulting from the algorithm’s recommendations with those based on the US Army caffeine-countermeasure guidelines. In addition, we enhanced the usability of the tool by adopting a drag-and-drop graphical interface for the creation of sleep and caffeine schedules. Results For the 4 simulated conditions, the 2B-Alert Web–proposed interventions increased mean alertness by 36% to 94% and decreased peak alertness impairment by 31% to 71% while using equivalent or smaller doses of caffeine as the corresponding US Army guidelines. Conclusions The enhanced capability of this evidence-based, publicly available tool increases the efficiency by which diverse communities of users can identify safe and effective caffeine interventions to mitigate the effects of sleep loss in the design of research studies and work and rest schedules.
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Jana R, Ramakrishnan S. Direct Generation of Internally Functionalized Nanoporous Polymers: Design of Polymerizable Porogens. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sarkar R, Mishra K, Das PK, Ramakrishnan S. Probing Polymer Chain Folding in Solution Using Second Harmonic Light Scattering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12457-12465. [PMID: 34641685 DOI: 10.1021/acs.langmuir.1c02156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Periodically grafted amphiphilic copolymers (PGACs) were earlier shown by us to adopt a zigzag folded conformation in the solid state, which enabled the backbone and pendant segments to segregate and occupy alternate layers in a lamellar structure. The conformational transition from a random coil to a zigzag folded chain in solution is an interesting problem, which is largely unexplored. To examine this, an orthogonally clickable parent polyester was sequentially clicked with two types of poly(ethylene glycol) (PEG) segments: one is a simple PEG and the other is a PEG that carries a dipolar chromophore. These two hydrophilic PEG segments, installed in a periodic and alternating fashion along the hydrocarbon-rich (HC) polyester backbone, ensure that the Janus folded chains are formed upon folding and carry chromophoric dipoles oriented along the same direction, thereby generating a large net dipole. The folding-induced alignment of chromophores in solution was followed using second harmonic light scattering (SHLS), wherein the intensity of the frequency-doubled scattered light (I2ω) is measured. Folding was induced by adding a polar solvent, like methanol, to a chloroform solution of the polymer; methanol desolvates the HC backbone but solubilizes the pendant PEG segments, thus inducing folding. The second harmonic intensity (I2ω) increased initially with methanol concentration and then saturated; in contrast, I2ω remained invariant with the solvent composition in the case of an analogous model chromophore. Furthermore, in a model PGAC carrying chromophore-bearing PEG segments on every repeat unit, I2ω decreased with increasing methanol composition, revealing the formation of a centrosymmetric folded chain, wherein the chromophoric dipoles on either side cancel each other. Thus, this study clearly reveals that the zigzag chain folding of PGACs can be induced by a segment-selective solvent, resulting in the rather elusive directional ordering of chromophoric dipoles in solution.
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Dwivedi C, Mohanty TR, Manjare SD, Rajan SK, Ramakrishnan S, Amarnath S, Lorenzetti D, Mohamed P. Application of non-ionic surfactant in modifying the surface of carbon black and its role in the formation of colloidal composite materials. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.126825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Laxminarayan S, Wang C, Ramakrishnan S, Oyama T, Cashmere JD, Germain A, Reifman J. Alterations in sleep electroencephalography synchrony in combat-exposed veterans with post-traumatic stress disorder. Sleep 2021; 43:5714726. [PMID: 31971594 DOI: 10.1093/sleep/zsaa006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 12/26/2019] [Indexed: 11/13/2022] Open
Abstract
STUDY OBJECTIVES We assessed whether the synchrony between brain regions, analyzed using electroencephalography (EEG) signals recorded during sleep, is altered in subjects with post-traumatic stress disorder (PTSD) and whether the results are reproducible across consecutive nights and subpopulations of the study. METHODS A total of 78 combat-exposed veteran men with (n = 31) and without (n = 47) PTSD completed two consecutive laboratory nights of high-density EEG recordings. We computed a measure of synchrony for each EEG channel-pair across three sleep stages (rapid eye movement [REM] and non-REM stages 2 and 3) and six frequency bands. We examined the median synchrony in 9 region-of-interest (ROI) pairs consisting of 6 bilateral brain regions (left and right frontal, central, and parietal regions) for 10 frequency-band and sleep-stage combinations. To assess reproducibility, we used the first 47 consecutive subjects (18 with PTSD) for initial discovery and the remaining 31 subjects (13 with PTSD) for replication. RESULTS In the discovery analysis, five alpha-band synchrony pairs during non-REM sleep were consistently larger in PTSD subjects compared with controls (effect sizes ranging from 0.52 to 1.44) across consecutive nights: two between the left-frontal and left-parietal ROIs, one between the left-central and left-parietal ROIs, and two across central and parietal bilateral ROIs. These trends were preserved in the replication set. CONCLUSION PTSD subjects showed increased alpha-band synchrony during non-REM sleep in the left frontoparietal, left centro-parietal, and inter-parietal brain regions. Importantly, these trends were reproducible across consecutive nights and subpopulations. Thus, these alterations in alpha synchrony may be discriminatory of PTSD.
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