104 results on '"Keshavarz B"'
Search Results
2. Motion sickness: current concepts and management
- Author
-
Keshavarz, B. and Golding, J.F.
- Subjects
age ,virtual reality ,sex ,simulator sickness - Abstract
Purpose of the review: Motion sickness is an ancient phenomenon that affects many people. Nausea, vomiting, disorientation, sweating, fatigue, and headache are just few of the many signs and symptoms that are commonly experienced during an episode of motion sickness. In the present review, we will provide an overview of the current research trends and topics in the domain of motion sickness, including theoretical considerations, physiological and neural mechanisms, individual risk factors, treatment options, as well as recommendations for future research directions. Recent findings: More recently, motion sickness has been in the focus of attention in the context of two global technological trends, namely automated vehicles and Virtual Reality (VR). Both technologies bear the potential to revolutionize our daily lives in many ways, however, motion sickness is considered a serious concern that threatens their success and acceptance. The majority of recent research on motion sickness focuses on one of these two areas. Summary: Aside from medication (e.g., antimuscarinics, antihistamines), habituation remains the most effective non-pharmacological method to reduce motion sickness. A variety of novel techniques has been investigated with promising results, but an efficient method to reliably prevent or minimize motion sickness has yet to emerge.
- Published
- 2022
3. Newtonian liquid jet impaction on a high-speed moving surface
- Author
-
Keshavarz, B., Green, S.I., Davy, M.H., and Eadie, D.T.
- Published
- 2011
- Full Text
- View/download PDF
4. P095 LEVELS OF IGG TO SARS-COV-2 IN RECIPIENTS OF COVID-19 VACCINES: LONGITUDINAL MONITORING WITH QUANTITATIVE ASSAY
- Author
-
Patel, J., primary, Keshavarz, B., additional, Richards, N., additional, Workman, L., additional, Muehling, L., additional, Murphy, D., additional, Eschenbacher, W., additional, Nelson, M., additional, Platts-Mills, T., additional, and Wilson, J., additional
- Published
- 2021
- Full Text
- View/download PDF
5. P309 BOTH FOOD AND AEROALLERGEN-SPECIFIC IGG4 LEVELS ARE ELEVATED IN PATIENTS WITH EOSINOPHILIC ESOPHAGITIS (EOE)
- Author
-
Li, R., primary, Keshavarz, B., additional, Wilson, J., additional, Workman, L., additional, Barnes, B., additional, Sauer, B., additional, Platts-Mills, T., additional, and McGowan, E., additional
- Published
- 2020
- Full Text
- View/download PDF
6. Microwave- and ultrasound-assisted extraction of phenolic and flavonoid compounds from konar (Ziziphus spina-christi) fruits.
- Author
-
Keshavarz, B. and Rezaei, K.
- Subjects
PHENOLS ,ZIZIPHUS ,TANNINS ,FRUIT ,WATER use - Abstract
Konar (Ziziphus spina-christi) fruit is known to have antioxidant and anti-inflammatory properties. In the present work, we investigated the yields for microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and magnetic stirrer extraction (MSE) methods using different extraction parameters including type of solvent, solvent to sample ratio (SSR), microwave irradiation power, extraction temperatures for MSE, microwave irradiation time, sonication time for UAE, and extraction time for MSE on the total phenolic (TP) and total flavonoid (TF) contents of the underutilised nutritious konar fruit. The highest TP content was obtained by MAE using water as solvent [10.3 ± 0.1 mg tannic acid equivalent (TAE) per gram (g) of sample]. However, the highest TF contents were obtained using ethanol in MAE [1.9 ± 0.0 mg quercetin equivalent (QE) per g of the sample], and methanol in UAE and MSE [1.7 ± 0.0 mg QE per g of sample]. An SSR of 15 resulted in the highest TP content while no significant differences were observed in the TF contents. MAE was considered the best extraction method for the extraction of TP and TF from konar fruits as demonstrated in the present work. [ABSTRACT FROM AUTHOR]
- Published
- 2020
7. Study of angiotensin converting enzyme (ACE) inhibitory effects of main Papaver spp. alkaloids
- Author
-
Seyed Ali Ziai, Mahmoudian, M., Keshavarz, B., Poorhoseini, L., Dastpak, A., Ebrahimi, A., and Farahani, A.
- Subjects
papaver spp ,inhibitory effects ,RA1190-1270 ,Toxicology. Poisons ,Therapeutics. Pharmacology ,RM1-950 ,alkaloids ,angiotensin converting enzyme ,ace - Abstract
Angiotensin converting enzyme (ACE) converts the inactive angiotensin I to (a potent vasoconstrictor and aldosterone releaser) angiotensin II. Inhibitors of ACE are valuable drugs in the treatment of hypertension, and heart failure. These inhibitors have a natural origin and non-peptide drugs were synthesized from the natural lead compounds. However, because of some side effects such as dry cough, many investigators are searching in natural products to find better and more selective lead compounds. There are reports on the interaction between rennin-angiotensin system and endogenous opioid system. Morphine and endogenous opioids have reported to inhibit ACE. In this research we examined the possible inhibitory effects of purified papaver’s main alkaloids on the activity of purified rabbit lung ACE. We found that only papaverin at 1 mM inhibited the enzyme by 40%. The Km value of ACE increased while Vmax decreased in papaverin treated samples. We conclude that part of hypotensive effects of papaverin may be related to ACE inhibition, and this compound will be a suitable lead compound for further investigation.
- Published
- 2004
8. Activated Carbon and Multiwalled Carbon Nanotubes an Efficient Adsorbents for Kinetic and Equilibrium Study of Removal of Arsenazo (???) and Methyl Red Dyes from Waste Water
- Author
-
SOYLAK, Mustafa, Ghaedi, M., Shojaiepoor, F, Shokrolahi, A., Keshavarz, B, Tavelli, H, Purkait, M.K., and Hossainian, H.
- Published
- 2011
9. Elastic liquid jet impaction on a high-speed moving surface
- Author
-
Keshavarz, B., primary, Green, S. I., additional, and Eadie, D. T., additional
- Published
- 2012
- Full Text
- View/download PDF
10. An Innovative Genetic Algorithm Approach for Direct Calibration of X-Probe Hot Wires
- Author
-
Manshadi, M.D., primary, Keshavarz, B., additional, Soltani, M.R., additional, and Ghorbanian, K., additional
- Published
- 2011
- Full Text
- View/download PDF
11. Activated carbon and multiwalled carbon nanotubes as efficient adsorbents for removal of arsenazo(ΙΙΙ) and methyl red from waste water
- Author
-
Ghaedi, M., primary, Shokrollahi, A., additional, Tavallali, H., additional, Shojaiepoor, F., additional, Keshavarz, B., additional, Hossainian, H., additional, Soylak, M., additional, and Purkait, M.K., additional
- Published
- 2010
- Full Text
- View/download PDF
12. An Innovative Genetic Algorithm Approach for Direct Calibration of X-Probe Hot Wires.
- Author
-
Manshadi, M.D., Keshavarz, B., Soltani, M.R., and Ghorbanian, K.
- Subjects
- *
GENETIC algorithms , *HOT-wire anemometer , *AIR flow , *GAS flow , *CALIBRATION , *ELECTRIC potential - Abstract
A new genetic algorithm (GA) based method for direct calibration of 2-D hot-wire probe and other instruments that can measure 2-D flow properties is introduced. This new method is an alternative for the previous QR method that is commonly used for calibration of the X-probe hot wires. The proposed GA method resulted in a much smaller error in the velocity estimation while preserving the number of sentences in its calibration equation format. In addition, it preserves the magnitude of its error even when the number of sentences in the calibration equation is decreased while the error in the QR method increases substantially for the same situation. Furthermore, the results were much closer to the real or natural behavior of the hot-wire data when compared with the QR method. Additionally, the GA method was applied for a large range of velocities (10-100 m/s) and the results revealed that the range of error did not vary significantly. The turbulent properties of the flow that were calculated by each method were not the same; however, the results from the GA method were smooth and had reasonable behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
13. Activated carbon and multiwalled carbon nanotubes as efficient adsorbents for removal of arsenazo(ΙΙΙ) and methyl red from waste water.
- Author
-
Ghaedi, M., Shokrollahi, A., Tavallali, H., Shojaiepoor, F., Keshavarz, B., Hossainian, H., Soylak, M., and Purkait, M. K.
- Subjects
ACTIVATED carbon ,CARBON nanotubes ,ADSORPTION (Chemistry) ,SEWAGE purification ,ARSENIC ,AZO dyes ,ATMOSPHERIC temperature ,THERMODYNAMICS - Abstract
In this study, removal of arsenazo(ΙΙΙ) using activated carbon (AC) and multiwalled carbon nanotubes and of methyl red using AC from waste water is reported. The influences of pH, temperature, concentration of the dye, amount of adsorbents, particle size of adsorbent, and contact time on the efficiency of removal from aqueous solution are investigated. Adsorption experiments indicate that the extent of adsorption is strongly dependent on the pH of the solution. Changes in free energy of adsorption ( [image omitted]), enthalpy ( [image omitted]), and entropy ( [image omitted]) are calculated to understand the nature of adsorption. The calculated values of [image omitted] indicate that the adsorption process is spontaneous. The estimated values of [image omitted] and [image omitted] are positive which indicates that the adsorption process is endothermic and that the dye molecules are organized on the adsorbent surface in a more random fashion than in solution. The dye adsorption process follows a pseudo-second-order model under involvement of an intra-particle diffusion mechanism. Standard adsorption isotherms are used to fit the experimental data. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
14. Axis Rotation and Visually Induced Motion Sickness: The Role of Combined Roll, Pitch, and Yaw Motion.
- Author
-
Keshavarz, B. and Hecht, H.
- Abstract
Background: Motion sickness (MS) is a well-known phenomenon in aviation and in virtual environments such as simulators or computer games. The severity of MS is thought to be due to the amount of sensory conflict, which should increase with the complexity of the simulated motion. The present study focused on the direction and complexity of simulated body rotations in the genesis and severity of visually induced MS. Methods: Three simulated rollercoaster rides including translational movement in the fore-aft axis and additional rotational motion either in pitch only, along the pitch and roll axes, or in pitch, roll, and yaw were generated. We presented video clips of 15 min on a large projection screen to a total number of 61 volunteers, who were randomly assigned to 1 of the 3 rotational motion groups. MS was measured using the Fast Motion Sickness Scale (20-point verbal rating scale) and the Simulator Sickness Questionnaire. Aftereffects were captured up to 5 h after the experiment was finished. Results: Analyses indicated lowest MS scores in the pitch-only condition (1.95). Dual- (4.33) or triple-axis (5.30) combinations revealed significantly higher MS scores than the single-axis condition, but surprisingly did not differ from each other. MS started to subside rapidly after about 1 h past stimulus presentation. Discussion: We conclude that the complexity of visual motion does not increase MS linearly. Instead, we propose that MS reached a plateau in the dual-axis condition and adding a third rotational axis did not further surpass the severity of MS reached. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
15. Distribution of extended spectrum beta-lactamase resistance genes among nosocomial imipenem resistant A. baumannii strains harboring BLA OXA-23 carbapenemases isolated from Ilam and Tehran
- Author
-
Morovat Taherikalani, Sekawi, Z., Azizi-Jalilian, F., Keshavarz, B., Soroush, S., Akbari, M., Emaneini, M., Asadollahi, P., Maleki, M. H., Mohammadi, S., Pakzad, I., Delpisheh, A., and Asadollahi, K.
16. Distribution of extended spectrum beta-lactamase resistance genes among nosocomial imipenem resistant A. baumannii strains harboring BLA OXA-23 carbapenemases isolated from Ilam and Tehran
- Author
-
Taherikalani, M., Sekawi, Z., Farid Azizi Jalilian, Keshavarz, B., Soroush, S., Akbari, M., Emaneini, M., Asadollahi, P., Maleki, M. H., Mohammadi, S., Pakzad, I., Delpisheh, A., and Asadollahi, K.
17. Individual factors and vection in younger and older adults: How sex, field dependence, personality, and visual attention do (or do not) affect illusory self-motion.
- Author
-
Murovec B, Spaniol J, and Keshavarz B
- Abstract
An important aspect to an immersive experience in Virtual Reality is vection, defined as the illusion of self-motion. Much of the literature to date has explored strategies to maximize vection through manipulations of the visual stimulus (e.g., increasing speed) or the experimental context (e.g., framing of the study instructions). However, the role of individual differences (e.g., age, biological sex) in vection susceptibility has received little attention. The objective of the current study was to investigate the influence of individual-difference factors on vection perception in younger and older adults. Forty-six younger adults ( M
age = 25.1) and 39 older adults ( Mage = 72.4) completed assessments of personality traits, field dependence, and visual attention prior to observing a moving visual stimulus aimed at inducing circular vection. Vection was measured using self-reports of onset latency, duration, and intensity. Results indicated that, in both age groups, females experienced longer-lasting vection compared to males. Additionally, the level of field dependence was related to vection intensity and duration in males but not in females. Variability in vection intensity was best explained by a mixture of biological, perceptual, cognitive, and personality variables. Taken together, these findings suggest that individual factors are important for understanding differences in vection susceptibility., Competing Interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2024.)- Published
- 2024
- Full Text
- View/download PDF
18. Aluminosilicate colloidal gels: from the early age to the precipitation of zeolites.
- Author
-
Poulesquen A, Gomes Rodrigues D, Keshavarz B, Courtois N, Ilavsky J, and McKinley GH
- Abstract
Aluminosilicate hydrogels are often considered to be precursors for the crystallisation of zeolites carried out under hydrothermal conditions. The preparation of mechanically homogeneous aluminosilicate gels enables the study of these materials through bulk rheology and observation of the aging dynamics until the precipitation of crystalline zeolites. The first part of this study deals with the establishment of ternary state diagrams, in order to identify the range of chemical formulations that enable preparation of single-phase homogeneous gels. Then, by studying the viscoelastic moduli during the gelation reaction, and by yielding the gel under large deformation, we propose an empirical law considering the partial order of reaction on each chemical element, to predict the gelation time according to the chemical formulation. The scaling behavior of the elastic properties of this colloidal gel shows a transition from a strong link behavior to a weak link regime. Long term aging results in the shrinkage of the gel, accompanied by syneresis of interstitial liquid at the surface. Zeolites precipitate through crystallisation by a particle attachment mechanism, when thermodynamic equilibrium is reached. The stoichiometry of the precipitated zeolites is not only consistent with the concentration of the remaining species in the supernatant but, surprisingly, it is also very close to the partial order of the reaction of the chemical elements involved in the determination of the critical gel point. This indicates a strong correlation between the morphology of the soft amorphous gel network that is formed at an early age and those of the final solid precipitated crystals.
- Published
- 2024
- Full Text
- View/download PDF
19. Targeting c-Myc with decoy oligodeoxynucleotide-loaded polycationic nanoparticles inhibits cell growth and induces apoptosis in cancer stem-like cells (NTERA-2).
- Author
-
Ghorbani R, Gharbavi M, Keshavarz B, Madanchi H, and Johari B
- Subjects
- Humans, Cell Line, Tumor, Nanocomposites chemistry, Polyelectrolytes chemistry, Oligodeoxyribonucleotides pharmacology, Oligodeoxyribonucleotides chemistry, Cell Survival drug effects, Silicon Dioxide chemistry, Polyamines chemistry, Polyamines pharmacology, Cell Cycle drug effects, Apoptosis drug effects, Neoplastic Stem Cells drug effects, Neoplastic Stem Cells metabolism, Proto-Oncogene Proteins c-myc metabolism, Proto-Oncogene Proteins c-myc genetics, Cell Proliferation drug effects, Nanoparticles chemistry
- Abstract
Background: An increase in cancer stem cell (CSC) populations and their resistance to common treatments could be a result of c-Myc dysregulations in certain cancer cells. In the current study, we investigated anticancer effects of c-Myc decoy ODNs loaded-poly (methacrylic acid-co-diallyl dimethyl ammonium chloride) (PMA-DDA)-coated silica nanoparticles as carriers on cancer-like stem cells (NTERA-2)., Methods and Results: The physicochemical characteristics of the synthesized nanocomposites (SiO
2 @PMA-DDA-DEC) were analyzed using FT-IR, DLS, and SEM techniques. UV-Vis spectrophotometer was applied to analyze the release pattern of decoy ODNs from the nanocomposite. Furthermore, uptake, cell viability, apoptosis, and cell cycle assays were used to investigate the anticancer effects of nanocomposites loaded with c-Myc decoy ODNs on NTERA-2 cancer cells. The results of physicochemical analytics demonstrated that SiO2 @PMA-DDA-DEC nanocomposites were successfully synthesized. The prepared nanocomposites were taken up by NTERA-2 cells with high efficiency, and could effectively inhibit cell growth and increase apoptosis rate in the treated cells compared to the control group. Moreover, SiO2 @PMA-DDA nanocomposites loaded with c-Myc decoy ODNs induced cell cycle arrest at the G0/G1 phase in the treated cells., Conclusions: The conclusion drawn from this study is that c-Myc decoy ODN-loaded SiO2 @PMA-DDA nanocomposites can effectively inhibit cell growth and induce apoptosis in NTERA-2 cancer cells. Moreover, given that a metal core is incorporated into this synthetic nanocomposite, it could potentially be used in conjunction with irradiation as part of a decoy-radiotherapy combinational therapy in future investigations., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)- Published
- 2024
- Full Text
- View/download PDF
20. Concussion can increase the risk of visually induced motion sickness.
- Author
-
Keshavarz B, Adams MS, Gabriel G, Sergio LE, and Campos JL
- Subjects
- Humans, Male, Female, Adult, Young Adult, Photic Stimulation methods, Photic Stimulation adverse effects, Visual Perception physiology, Motion Sickness physiopathology, Motion Sickness etiology, Brain Concussion physiopathology, Brain Concussion psychology
- Abstract
Concussion can lead to various symptoms such as balance problems, memory impairments, dizziness, and/or headaches. It has been previously suggested that during self-motion relevant tasks, individuals with concussion may rely heavily on visual information to compensate for potentially less reliable vestibular inputs and/or problems with multisensory integration. As such, concussed individuals may also be more sensitive to other visually-driven sensations such as visually induced motion sickness (VIMS). To investigate whether concussed individuals are at elevated risk of experiencing VIMS, we exposed participants with concussion (n = 16) and healthy controls (n = 15) to a virtual scene depicting visual self-motion down a grocery store aisle at different speeds. Participants with concussion were further separated into symptomatic and asymptomatic groups. VIMS was measured with the SSQ before and after stimulus exposure, and visual dependence, self-reported dizziness, and somatization were recorded at baseline. Results showed that concussed participants who were symptomatic demonstrated significantly higher SSQ scores after stimulus presentation compared to healthy controls and those who were asymptomatic. Visual dependence was positively correlated with the level of VIMS in healthy controls and participants with concussion. Our results suggest that the presence of concussion symptoms at time of testing significantly increased the risk and severity of VIMS. This finding is of relevance with regards to the use of visual display devices such as Virtual Reality applications in the assessment and rehabilitation of individuals with concussion., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
21. Distinct Type 1 Immune Networks Underlie the Severity of Restrictive Lung Disease after COVID-19.
- Author
-
Canderan G, Muehling LM, Kadl A, Ladd S, Bonham C, Cross CE, Lima SM, Yin X, Sturek JM, Wilson JM, Keshavarz B, Bryant N, Murphy DD, Cheon IS, McNamara CA, Sun J, Utz PJ, Dolatshahi S, Irish JM, and Woodfolk JA
- Abstract
The variable etiology of persistent breathlessness after COVID-19 have confounded efforts to decipher the immunopathology of lung sequelae. Here, we analyzed hundreds of cellular and molecular features in the context of discrete pulmonary phenotypes to define the systemic immune landscape of post-COVID lung disease. Cluster analysis of lung physiology measures highlighted two phenotypes of restrictive lung disease that differed by their impaired diffusion and severity of fibrosis. Machine learning revealed marked CCR5+CD95+ CD8+ T-cell perturbations in mild-to-moderate lung disease, but attenuated T-cell responses hallmarked by elevated CXCL13 in more severe disease. Distinct sets of cells, mediators, and autoantibodies distinguished each restrictive phenotype, and differed from those of patients without significant lung involvement. These differences were reflected in divergent T-cell-based type 1 networks according to severity of lung disease. Our findings, which provide an immunological basis for active lung injury versus advanced disease after COVID-19, might offer new targets for treatment.
- Published
- 2024
- Full Text
- View/download PDF
22. Measuring vection: a review and critical evaluation of different methods for quantifying illusory self-motion.
- Author
-
Kooijman L, Berti S, Asadi H, Nahavandi S, and Keshavarz B
- Subjects
- Humans, Motion, Motion Perception physiology, Illusions physiology
- Abstract
The sensation of self-motion in the absence of physical motion, known as vection, has been scientifically investigated for over a century. As objective measures of, or physiological correlates to, vection have yet to emerge, researchers have typically employed a variety of subjective methods to quantify the phenomenon of vection. These measures can be broadly categorized into the occurrence of vection (e.g., binary choice yes/no), temporal characteristics of vection (e.g., onset time/latency, duration), the quality of the vection experience (e.g., intensity rating scales, magnitude estimation), or indirect (e.g., distance travelled) measures. The present review provides an overview and critical evaluation of the most utilized vection measures to date and assesses their respective merit. Furthermore, recommendations for the selection of the most appropriate vection measures will be provided to assist with the process of vection research and to help improve the comparability of research findings across different vection studies., (© 2023. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
23. The presence of an avatar can reduce cybersickness in Virtual Reality.
- Author
-
Makani A, Saryazdi R, Givetash S, and Keshavarz B
- Abstract
Virtual Reality (VR) applications are increasingly being utilized for research, healthcare, and education. Despite their benefits, many VR users report motion sickness-like sensations (cybersickness), such as headache, disorientation, or nausea. Previous studies suggest that the sense of presence ("being there") in the virtual world may contribute to the severity of cybersickness; however, results have been contradictory, with some studies reporting a negative and some reporting a positive relationship between the two. The goal of the current study was to further investigate how presence and cybersickness are related. Participants ( N = 54) were exposed to a VR scene presented on a head-mounted display showing a 15-minute-long passive movement through space. The level of presence was manipulated by including an avatar (astronaut suit with hand-tracking) or no avatar in the virtual environment. Results showed that the avatar group reported significantly less severe cybersickness compared to the no-avatar group. We also found significant, negative correlations between some of the presence metrics (immersion, sensory fidelity) and cybersickness, indicating that cybersickness severity decreased as the level of presence increased. These findings suggest that more immersive VR experiences using an avatar may potentially reduce the risk of experiencing cybersickness., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2024.)
- Published
- 2024
- Full Text
- View/download PDF
24. Beyond the Eye: Multisensory Contributions to the Sensation of Illusory Self-Motion (Vection).
- Author
-
Riecke BE, Murovec B, Campos JL, and Keshavarz B
- Subjects
- Humans, Sensation, Motion, Illusions physiology, Motion Perception physiology, Motion Sickness
- Abstract
Vection is typically defined as the embodied illusion of self-motion in the absence of real physical movement through space. Vection can occur in real-life situations (e.g., 'train illusion') and in virtual environments and simulators. The vast majority of vection research focuses on vection caused by visual stimulation. Even though visually induced vection is arguably the most compelling type of vection, the role of nonvisual sensory inputs, such as auditory, biomechanical, tactile, and vestibular cues, have recently gained more attention. Non-visual cues can play an important role in inducing vection in two ways. First, nonvisual cues can affect the occurrence and strength of vection when added to corresponding visual information. Second, nonvisual cues can also elicit vection in the absence of visual information, for instance when observers are blindfolded or tested in darkness. The present paper provides a narrative review of the literature on multimodal contributions to vection. We will discuss both the theoretical and applied relevance of multisensory processing as related to the experience of vection and provide design considerations on how to enhance vection in various contexts.
- Published
- 2023
- Full Text
- View/download PDF
25. Exploring neurophysiological correlates of visually induced motion sickness using electroencephalography (EEG).
- Author
-
Andrievskaia P, Berti S, Spaniol J, and Keshavarz B
- Subjects
- Humans, Cognition, Electroencephalography, Fatigue, Neurophysiology, Motion Sickness etiology
- Abstract
Visually induced motion sickness (VIMS) is a common phenomenon when using visual devices such as smartphones and virtual reality applications, with symptoms including nausea, fatigue, and headache. To date, the neuro-cognitive processes underlying VIMS are not fully understood. Previous studies using electroencephalography (EEG) delivered mixed findings, with some reporting an increase in delta and theta power, and others reporting increases in alpha and beta frequencies. The goal of the study was to gain further insight into EEG correlates for VIMS. Participants viewed a VIMS-inducing visual stimulus, composed of moving black-and-white vertical bars presented on an array of three adjacent monitors. The EEG was recorded during visual stimulation and VIMS ratings were recorded after each trial using the Fast Motion Sickness Scale. Time-frequency analyses were conducted comparing neural activity of participants reporting minimal VIMS (n = 21) and mild-moderate VIMS (n = 12). Results suggested a potential increase in delta power in the centro-parietal regions (CP2) and a decrease in alpha power in the central regions (Cz) for participants experiencing mild-moderate VIMS compared to those with minimal VIMS. Event-related spectral perturbations (ERSPs) suggested that group differences in EEG activity developed with increasing duration of a trial. These results support the hypothesis that the EEG might be sensitive to differences in information processing in VIMS and minimal VIMS contexts, and indicate that it may be possible to identify neurophysiological correlate of VIMS. Differences in EEG activity related to VIMS may reflect differential processing of conflicting visual and vestibular sensory information., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
- Published
- 2023
- Full Text
- View/download PDF
26. In-depth cellular and humoral dynamics of the response to COVID-19 vaccine booster in patients with chronic B-cell neoplasms.
- Author
-
Ayers E, Canderan G, Williams ME, Keshavarz B, Portell CA, Wilson JM, and Woodfolk JA
- Subjects
- Humans, COVID-19 prevention & control, Neoplasms
- Published
- 2023
- Full Text
- View/download PDF
27. Exploring the merits of research performance measures that comply with the San Francisco Declaration on Research Assessment and strategies to overcome barriers of adoption: qualitative interviews with administrators and researchers.
- Author
-
Boury H, Albert M, Chen RHC, Chow JCL, DaCosta R, Hoffman MM, Keshavarz B, Kontos P, McAndrews MP, Protze S, and Gagliardi AR
- Abstract
Background: In prior research, we identified and prioritized ten measures to assess research performance that comply with the San Francisco Declaration on Research Assessment, a principle adopted worldwide that discourages metrics-based assessment. Given the shift away from assessment based on Journal Impact Factor, we explored potential barriers to implementing and adopting the prioritized measures., Methods: We identified administrators and researchers across six research institutes, conducted telephone interviews with consenting participants, and used qualitative description and inductive content analysis to derive themes., Results: We interviewed 18 participants: 6 administrators (research institute business managers and directors) and 12 researchers (7 on appointment committees) who varied by career stage (2 early, 5 mid, 5 late). Participants appreciated that the measures were similar to those currently in use, comprehensive, relevant across disciplines, and generated using a rigorous process. They also said the reporting template was easy to understand and use. In contrast, a few administrators thought the measures were not relevant across disciplines. A few participants said it would be time-consuming and difficult to prepare narratives when reporting the measures, and several thought that it would be difficult to objectively evaluate researchers from a different discipline without considerable effort to read their work. Strategies viewed as necessary to overcome barriers and support implementation of the measures included high-level endorsement of the measures, an official launch accompanied by a multi-pronged communication strategy, training for both researchers and evaluators, administrative support or automated reporting for researchers, guidance for evaluators, and sharing of approaches across research institutes., Conclusions: While participants identified many strengths of the measures, they also identified a few limitations and offered corresponding strategies to address the barriers that we will apply at our organization. Ongoing work is needed to develop a framework to help evaluators translate the measures into an overall assessment. Given little prior research that identified research assessment measures and strategies to support adoption of those measures, this research may be of interest to other organizations that assess the quality and impact of research., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
28. DORA-compliant measures of research quality and impact to assess the performance of researchers in biomedical institutions: Review of published research, international best practice and Delphi survey.
- Author
-
Gagliardi AR, Chen RHC, Boury H, Albert M, Chow J, DaCosta RS, Hoffman M, Keshavarz B, Kontos P, Liu J, McAndrews MP, and Protze S
- Subjects
- Consensus, Journal Impact Factor, Surveys and Questionnaires, Delphi Technique, Delivery of Health Care, Research Design
- Abstract
Objective: The San Francisco Declaration on Research Assessment (DORA) advocates for assessing biomedical research quality and impact, yet academic organizations continue to employ traditional measures such as Journal Impact Factor. We aimed to identify and prioritize measures for assessing research quality and impact., Methods: We conducted a review of published and grey literature to identify measures of research quality and impact, which we included in an online survey. We assembled a panel of researchers and research leaders, and conducted a two-round Delphi survey to prioritize measures rated as high (rated 6 or 7 by ≥ 80% of respondents) or moderate (rated 6 or 7 by ≥ 50% of respondents) importance., Results: We identified 50 measures organized in 8 domains: relevance of the research program, challenges to research program, or productivity, team/open science, funding, innovations, publications, other dissemination, and impact. Rating of measures by 44 panelists (60%) in Round One and 24 (55%) in Round Two of a Delphi survey resulted in consensus on the high importance of 5 measures: research advances existing knowledge, research plan is innovative, an independent body of research (or fundamental role) supported by peer-reviewed research funding, research outputs relevant to discipline, and quality of the content of publications. Five measures achieved consensus on moderate importance: challenges to research productivity, potential to improve health or healthcare, team science, collaboration, and recognition by professional societies or academic bodies. There was high congruence between researchers and research leaders across disciplines., Conclusions: Our work contributes to the field by identifying 10 DORA-compliant measures of research quality and impact, a more comprehensive and explicit set of measures than prior efforts. Research is needed to identify strategies to overcome barriers of use of DORA-compliant measures, and to "de-implement" traditional measures that do not uphold DORA principles yet are still in use., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Gagliardi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
- Published
- 2023
- Full Text
- View/download PDF
29. Measuring the susceptibility to visually induced motion sickness and its relationship with vertigo, dizziness, migraine, syncope and personality traits.
- Author
-
Lukacova I, Keshavarz B, and Golding JF
- Subjects
- Humans, Adult, Dizziness complications, Vertigo complications, Syncope complications, Personality, Motion Sickness etiology, Migraine Disorders complications
- Abstract
The widespread use of visual technologies such as Virtual Reality increases the risk of visually induced motion sickness (VIMS). Previously, the 6-item short version of the Visually Induced Motion Sickness Susceptibility Questionnaire (VIMSSQ short form) has been validated for predicting individual variation in VIMS. The aim of the current study was to investigate how the susceptibility to VIMS is correlated with other relevant factors in the general population. A total of 440 participants (201 M, 239F), mean age 33.6 (SD 14.8) years, completed an anonymous online survey of various questionnaires including the VIMSSQ, Motion Sickness Susceptibility Questionnaire (MSSQ), Vertigo in City questionnaire (VIC), Migraine (scale), Social & Work Impact of Dizziness (SWID), Syncope (faintness), and Personality ('Big Five' TIPI). The VIMSSQ correlated positively with the MSSQ (r = 0.50), VIC (r = 0.45), Migraine (r = 0.44), SWID (r = 0.28), and Syncope (r = 0.15). The most efficient Multiple Linear Regression model for the VIMSSQ included the predictors MSSQ, Migraine, VIC, and Age and explained 40% of the variance. Factor analysis of strongest correlates with VIMSSQ revealed a single factor loading with VIMSSQ, MSSQ, VIC, Migraine, SWID, and Syncope, suggesting a common latent variable of sensitivity. The set of predictors for the VIMSSQ in the general population has similarity with those often observed in patients with vestibular disorders. Based on these correlational results, we suggest the existence of continuum of underlying risk factors for sensitivity, from healthy population to patients with extreme visual vertigo and perhaps Persistent Postural-Perceptual Dizziness., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
30. Food antigen consumption and disease activity affect food-specific IgG4 levels in patients with eosinophilic esophagitis (EoE).
- Author
-
McGowan EC, Medernach J, Keshavarz B, Workman LJ, Li RC, Barnes BH, Sauer B, Wilson JM, and Platts-Mills TAE
- Subjects
- Humans, Animals, Prospective Studies, Immunoglobulin G, Case-Control Studies, Immunoglobulin E, Allergens, Milk, Eosinophilic Esophagitis
- Abstract
Introduction: High levels of serum food-specific IgG4 (sIgG4) have been reported in patients with EoE. The objective of this study was to examine whether serum sIgG4 levels to foods and aeroallergens are higher in EoE patients than allergic controls and to investigate the association between sIgG4 and EoE clinical characteristics., Methods: This was a case-control study nested in a prospective EoE Cohort. EoE cases were defined per consensus guidelines, and controls were individuals with symptoms who were confirmed to be EoE-negative on upper endoscopy. Demographic and clinical information was prospectively collected. Serum IgE and sIgG4 were measured to foods and aeroallergens by ImmunoCAP. Mean levels of sIgG4 were compared between cases and controls, and logistic regression models were used to examine predictors of elevated milk sIgG4 levels., Results: The analysis included 123 individuals (EoE n = 93, control n = 30) with a similar distribution of allergic disease between EoE patients and controls (86% vs. 93%; p = .30). EoE patients had significantly higher sIgG4 levels to all allergens evaluated, with the exception of birch (p = .24). Milk sIgG4 levels were independently associated with milk consumption (OR 4.95; p = .01) and the presence of sIgE to milk (OR 4.23; p = .008)., Conclusion: Serum sIgG4 levels to food and aeroallergen proteins were higher in patients with EoE than non-EoE controls, and higher levels of milk sIgG4 were independently associated with milk consumption and the presence of sIgE to milk proteins. Whether sIgG4 plays a pathogenic role in EoE or could be used as an EoE biomarker remains unknown and warrants further study., (© 2022 John Wiley & Sons Ltd.)
- Published
- 2023
- Full Text
- View/download PDF
31. The Visually Induced Motion Sickness Susceptibility Questionnaire (VIMSSQ): Estimating Individual Susceptibility to Motion Sickness-Like Symptoms When Using Visual Devices.
- Author
-
Keshavarz B, Murovec B, Mohanathas N, and Golding JF
- Subjects
- Male, Female, Humans, Reproducibility of Results, Surveys and Questionnaires, Asthenopia etiology, Motion Sickness, Virtual Reality
- Abstract
Objective: Two studies were conducted to develop and validate a questionnaire to estimate individual susceptibility to visually induced motion sickness (VIMS)., Background: VIMS is a common side-effect when watching dynamic visual content from various sources, such as virtual reality, movie theaters, or smartphones. A reliable questionnaire predicting individual susceptibility to VIMS is currently missing. The aim was to fill this gap by introducing the Visually Induced Motion Sickness Susceptibility Questionnaire (VIMSSQ)., Methods: A survey and an experimental study were conducted. Survey: The VIMSSQ investigated the frequency of nausea, headache, dizziness, fatigue, and eyestrain when using different visual devices. Data were collected from a survey of 322 participants for the VIMSSQ and other related phenomena such as migraine. Experimental study: 23 participants were exposed to a VIMS-inducing visual stimulus. Participants filled out the VIMSSQ together with other questionnaires and rated their level of VIMS using the Simulator Sickness Questionnaire (SSQ)., Results: Survey: The most prominent symptom when using visual devices was eyestrain, and females reported more VIMS than males. A one-factor solution with good scale reliability was found for the VIMSSQ. Experimental study: Regression analyses suggested that the VIMSSQ can be useful in predicting VIMS ( R
2 = .34) as measured by the SSQ, particularly when combined with questions pertaining to the tendency to avoid visual displays and experience syncope ( R2 = .59)., Conclusion: We generated normative data for the VIMSSQ and demonstrated its validity., Application: The VIMSSQ can become a valuable tool to estimate one's susceptibility to VIMS based on self-reports.- Published
- 2023
- Full Text
- View/download PDF
32. Enhanced SARS-CoV-2 IgG durability following COVID-19 mRNA booster vaccination and comparison of BNT162b2 with mRNA-1273.
- Author
-
Ailsworth SM, Keshavarz B, Richards NE, Workman LJ, Murphy DD, Nelson MR, Platts-Mills TAE, and Wilson JM
- Subjects
- Adult, Humans, 2019-nCoV Vaccine mRNA-1273, SARS-CoV-2, COVID-19 Vaccines, Immunoglobulin G, Antibodies, Viral, Vaccination, BNT162 Vaccine, COVID-19 prevention & control
- Abstract
Background: BNT162b2 (Pfizer/BioNTech, Comirnaty) and mRNA-1273 (Moderna, Spikevax) are messenger RNA (mRNA) vaccines that elicit antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike receptor-binding domain (S-RBD) and have been approved by the US Food and Drug Administration to combat the coronavirus disease 2019 (COVID-19) pandemic. Because vaccine efficacy and antibody levels waned over time after the 2-shot primary series, the US Food and Drug Administration authorized a booster (third) dose for both mRNA vaccines to adults in the fall of 2021., Objective: To evaluate the magnitude and durability of S-RBD immunoglobulin (Ig)G after the booster mRNA vaccine dose in comparison to the primary series. We also compared S-RBD IgG levels after BNT162b2 and mRNA-1273 boosters and explored effects of age and prior infection., Methods: Surrounding receipt of the second and third homologous mRNA vaccine doses, adults in an employee-based cohort provided serum and completed questionnaires, including information about previous COVID-19 infection. The IgG to S-RBD was measured using an ImmunoCAP-based system. A subset of samples were assayed for IgG to SARS-CoV-2 nucleocapsid by commercial assay., Results: There were 228 subjects who had samples collected between 7 and 150 days after their primary series vaccine and 117 subjects who had samples collected in the same time frame after their boost. Antibody levels from 7 to 31 days after the primary series and booster were similar, but S-RBD IgG was more durable over time after the boost, regardless of prior infection status. In addition, mRNA-1273 post-boost antibody levels exceeded BNT162b2 out to 5 months., Conclusion: The COVID-19 mRNA vaccine boosters increase antibody durability, suggesting enhanced long-term clinical protection from SARS-CoV-2 infection compared with the 2-shot regimen., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
33. Enhanced vection in older adults: Evidence for age-related effects in multisensory vection experiences.
- Author
-
Murovec B, Spaniol J, Campos JL, and Keshavarz B
- Abstract
The illusion of self-motion (vection) is a multisensory phenomenon elicited by visual, auditory, tactile, or other sensory cues. Aging is often associated with changes in sensory acuity, visual motion perception, and multisensory integration, processes which may influence vection perception. However, age-related differences in vection have received little study to date. Thus, the objective of the present study was to investigate age-related differences in vection during multisensory stimulation. Nineteen younger adults and 19 older adults were exposed to rotating visual, auditory, and tactile stimuli (separately or in combination) at a speed of 45°/s inside a VR laboratory inducing circular vection. The size of the field-of-view (FOV) was large (240°), medium (75°), small (30°), or contained no visuals. Vection intensity and duration were reported verbally after each trial. Overall, older adults experienced significantly stronger and longer vection compared to younger adults. Additionally, there were main effects of FOV and sensory cues, such that larger FOVs and the presence of auditory and tactile stimulation increased vection ratings for both age groups. These findings support the idea that vection is a multisensory experience that can be elicited by visual, auditory, and tactile stimuli and demonstrates these effects for the first time in older adults.
- Published
- 2022
- Full Text
- View/download PDF
34. Detecting and predicting visually induced motion sickness with physiological measures in combination with machine learning techniques.
- Author
-
Keshavarz B, Peck K, Rezaei S, and Taati B
- Subjects
- Adult, Female, Humans, Machine Learning, Male, Photic Stimulation, Surveys and Questionnaires, Motion Sickness, Virtual Reality
- Abstract
Visually induced motion sickness (VIMS) is a common sensation when using visual displays such as smartphones or Virtual Reality. In the present study, we investigated whether Machine Learning (ML) techniques in combination with physiological measures (ECG, EDA, EGG, respiration, body and skin temperature, and body movements) could be used to detect and predict the severity of VIMS in real-time, minute-by-minute. A total of 43 healthy younger adults (25 female) were exposed to a 15-minute VIMS-inducing video. VIMS severity was subjectively measured during the video using the Fast Motion Sickness Scale (FMS) as well as before and after the video using the Simulator Sickness Questionnaire (SSQ). Thirty-one participants (72%) experienced VIMS in the present study. Results showed that changes in facial skin temperature and body movement had the strongest relationship with VIMS. On a minute-by-minute basis, ML models revealed a medium correlation between the physiological measures and the FMS scores. An acceptable classification score distinguishing between sick and non-sick participants was found. Our findings suggest that physiological measures may be useful for measuring VIMS, but they are not a reliable standalone method to detect or predict VIMS severity in real-time., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
35. Trajectory of IgG to SARS-CoV-2 After Vaccination With BNT162b2 or mRNA-1273 in an Employee Cohort and Comparison With Natural Infection.
- Author
-
Keshavarz B, Richards NE, Workman LJ, Patel J, Muehling LM, Canderan G, Murphy DD, Brovero SG, Ailsworth SM, Eschenbacher WH, McGowan EC, Mann BJ, Nelson MR, Kadl A, Woodfolk JA, Platts-Mills TAE, and Wilson JM
- Subjects
- 2019-nCoV Vaccine mRNA-1273, Ad26COVS1, Antibodies, Viral, COVID-19 Vaccines, Humans, Immunoglobulin G, SARS-CoV-2, United States, Vaccination, BNT162 Vaccine, COVID-19 prevention & control
- Abstract
Three COVID-19 vaccines have received FDA-authorization and are in use in the United States, but there is limited head-to-head data on the durability of the immune response elicited by these vaccines. Using a quantitative assay we studied binding IgG antibodies elicited by BNT162b2, mRNA-1273 or Ad26.COV2.S in an employee cohort over a span out to 10 months. Age and sex were explored as response modifiers. Of 234 subjects in the vaccine cohort, 114 received BNT162b2, 114 received mRNA-1273 and six received Ad26.COV2.S. IgG levels measured between seven to 20 days after the second vaccination were similar in recipients of BNT162b2 and mRNA-127 and were ~50-fold higher than in recipients of Ad26.COV2.S. However, by day 21 and at later time points IgG levels elicited by BNT162b2 were lower than mRNA-1273. Accordingly, the IgG decay curve was steeper for BNT162b2 than mRNA-1273. Age was a significant modifier of IgG levels in recipients of BNT162b2, but not mRNA-1273. After six months, IgG levels elicited by BNT162b2, but not mRNA-1273, were lower than IgG levels in patients who had been hospitalized with COVID-19 six months earlier. Similar findings were observed when comparing vaccine-elicited antibodies with steady-state IgG targeting seasonal human coronaviruses. Differential IgG decay could contribute to differences observed in clinical protection over time between BNT162b2 and mRNA-1273., Competing Interests: TP-M and JMW have received assay support from Thermo-Fisher/Phadia, but not for work related to this project. JMW has received consultancy fees from Thermo-Fisher/Phadia for work unrelated to this project. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Keshavarz, Richards, Workman, Patel, Muehling, Canderan, Murphy, Brovero, Ailsworth, Eschenbacher, McGowan, Mann, Nelson, Kadl, Woodfolk, Platts-Mills and Wilson.)
- Published
- 2022
- Full Text
- View/download PDF
36. Motion sickness: current concepts and management.
- Author
-
Keshavarz B and Golding JF
- Subjects
- Autonomous Vehicles, Fatigue, Humans, Vomiting, Motion Sickness therapy, Virtual Reality
- Abstract
Purpose of Review: Motion sickness is an ancient phenomenon that affects many people. Nausea, vomiting, disorientation, sweating, fatigue, and headache are just few of the many signs and symptoms that are commonly experienced during an episode of motion sickness. In the present review, we will provide an overview of the current research trends and topics in the domain of motion sickness, including theoretical considerations, physiological and neural mechanisms, individual risk factors, and treatment options, as well as recommendations for future research directions., Recent Findings: More recently, motion sickness has been in the focus of attention in the context of two global technological trends, namely automated vehicles and virtual reality. Both technologies bear the potential to revolutionize our daily lives in many ways; however, motion sickness is considered a serious concern that threatens their success and acceptance. The majority of recent research on motion sickness focuses on one of these two areas., Summary: Aside from medication (e.g. antimuscarinics, antihistamines), habituation remains the most effective nonpharmacological method to reduce motion sickness. A variety of novel techniques has been investigated with promising results, but an efficient method to reliably prevent or minimize motion sickness has yet to emerge., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
37. Of mice and men, MMXXI: Anaphylaxis.
- Author
-
Platts-Mills TAE, Eid RC, and Keshavarz B
- Subjects
- Humans, Immunoglobulin E, Anaphylaxis diagnosis, Food Hypersensitivity
- Published
- 2022
- Full Text
- View/download PDF
38. Virtual Hand Illusion in younger and older adults.
- Author
-
Campos JL, El-Khechen Richandi G, Coahran M, Fraser LE, Taati B, and Keshavarz B
- Abstract
Introduction: Embodiment involves experiencing ownership over our body and localizing it in space and is informed by multiple senses (visual, proprioceptive and tactile). Evidence suggests that embodiment and multisensory integration may change with older age. The Virtual Hand Illusion (VHI) has been used to investigate multisensory contributions to embodiment, but has never been evaluated in older adults. Spatio-temporal factors unique to virtual environments may differentially affect the embodied perceptions of older and younger adults., Methods: Twenty-one younger (18-35 years) and 19 older (65+ years) adults completed the VHI paradigm. Body localization was measured at baseline and again, with subjective ownership ratings, following synchronous and asynchronous visual-tactile interactions., Results: Higher ownership ratings were observed in the synchronous relative to the asynchronous condition, but no effects on localization/drift were found. No age differences were observed. Localization accuracy was biased in both age groups when the virtual hand was aligned with the real hand, indicating a visual mislocalization of the virtual hand., Conclusions: No age-related differences in the VHI were observed. Mislocalization of the hand in VR occurred for both groups, even when congruent and aligned; however, tactile feedback reduced localization biases. Our results expand the current understanding of age-related changes in multisensory embodiment within virtual environments., Competing Interests: Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2021.)
- Published
- 2021
- Full Text
- View/download PDF
39. Reply to: The antibody response to the glycan α-Gal correlates with COVID-19 symptoms.
- Author
-
Wilson JM, Platts-Mills TAE, and Keshavarz B
- Subjects
- Antibody Formation, Humans, Polysaccharides, SARS-CoV-2, COVID-19
- Published
- 2021
- Full Text
- View/download PDF
40. Comparison of SARS-CoV-2 Antibody Response by Age Among Recipients of the BNT162b2 vs the mRNA-1273 Vaccine.
- Author
-
Richards NE, Keshavarz B, Workman LJ, Nelson MR, Platts-Mills TAE, and Wilson JM
- Subjects
- 2019-nCoV Vaccine mRNA-1273, Adult, Age Factors, BNT162 Vaccine, Female, Humans, Immunoglobulin G blood, Immunoglobulin G immunology, Male, Middle Aged, SARS-CoV-2 immunology, Spike Glycoprotein, Coronavirus blood, Spike Glycoprotein, Coronavirus immunology, Antibody Formation, COVID-19 immunology, COVID-19 Vaccines immunology
- Published
- 2021
- Full Text
- View/download PDF
41. Spectral Universality of Elastoinertial Turbulence.
- Author
-
Yamani S, Keshavarz B, Raj Y, Zaki TA, McKinley GH, and Bischofberger I
- Abstract
Dissolving small amounts of polymer into a Newtonian fluid can dramatically change the dynamics of transitional and turbulent flows. We investigate the spatiotemporal dynamics of a submerged jet of dilute polymer solution entering a quiescent bath of Newtonian fluid. High-speed digital Schlieren imaging is used to quantify the evolution of Lagrangian features in the jet revealing a rich sequence of transitional and turbulent states. At high levels of viscoelasticity, we identify a new distinct transitional pathway to elastoinertial turbulence (EIT) that does not feature the conventional turbulent bursts and instead proceeds via a shear-layer instability that produces elongated filaments of polymer due to the nonlinear effects of viscoelasticity. Even though the pathways to the EIT state can be different, and within EIT the spatial details of the turbulent structures vary systematically with polymer microstructure and concentration, there is a universality in the power-law spectral decay of EIT with frequency, f^{-3}, independent of fluid rheology and flow parameters.
- Published
- 2021
- Full Text
- View/download PDF
42. Multisensory Effects on Illusory Self-Motion (Vection): the Role of Visual, Auditory, and Tactile Cues.
- Author
-
Murovec B, Spaniol J, Campos JL, and Keshavarz B
- Abstract
A critical component to many immersive experiences in virtual reality (VR) is vection, defined as the illusion of self-motion. Traditionally, vection has been described as a visual phenomenon, but more recent research suggests that vection can be influenced by a variety of senses. The goal of the present study was to investigate the role of multisensory cues on vection by manipulating the availability of visual, auditory, and tactile stimuli in a VR setting. To achieve this, 24 adults (Mage = 25.04) were presented with a rotating stimulus aimed to induce circular vection. All participants completed trials that included a single sensory cue, a combination of two cues, or all three cues presented together. The size of the field of view (FOV) was manipulated across four levels (no-visuals, small, medium, full). Participants rated vection intensity and duration verbally after each trial. Results showed that all three sensory cues induced vection when presented in isolation, with visual cues eliciting the highest intensity and longest duration. The presence of auditory and tactile cues further increased vection intensity and duration compared to conditions where these cues were not presented. These findings support the idea that vection can be induced via multiple types of sensory inputs and can be intensified when multiple sensory inputs are combined.
- Published
- 2021
- Full Text
- View/download PDF
43. Carbohydrate epitopes currently recognized as targets for IgE antibodies.
- Author
-
Platts-Mills TA, Hilger C, Jappe U, van Hage M, Gadermaier G, Spillner E, Lidholm J, Keshavarz B, Aalberse RC, van Ree R, Goodman RE, and Pomés A
- Subjects
- Animals, Carbohydrates, Cross Reactions, Epitopes, Humans, Allergens, Immunoglobulin E
- Abstract
Until recently, glycan epitopes have not been documented by the WHO/IUIS Allergen Nomenclature Sub-Committee. This was in part due to scarce or incomplete information on these oligosaccharides, but also due to the widely held opinion that IgE to these epitopes had little or no relevance to allergic symptoms. Most IgE-binding glycans recognized up to 2008 were considered to be "classical" cross-reactive carbohydrate determinants (CCD) that occur in insects, some helminths and throughout the plant kingdom. Since 2008, the prevailing opinion on lack of clinical relevance of IgE-binding glycans has been subject to a reevaluation. This was because IgE specific for the mammalian disaccharide galactose-alpha-1,3-galactose (alpha-gal) was identified as a cause of delayed anaphylaxis to mammalian meat in the United States, an observation that has been confirmed by allergists in many parts of the world. Several experimental studies have shown that oligosaccharides with one or more terminal alpha-gal epitopes can be attached as a hapten to many different mammalian proteins or lipids. The classical CCDs also behave like haptens since they can be expressed on proteins from multiple species. This is the explanation for extensive in vitro cross-reactivity related to CCDs. Because of these developments, the Allergen Nomenclature Sub-Committee recently decided to include glycans as potentially allergenic epitopes in an adjunct section of its website (www.allergen.org). In this article, the features of the main glycan groups known to be involved in IgE recognition are revisited, and their characteristic structural, functional, and clinical features are discussed., (© 2021 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.)
- Published
- 2021
- Full Text
- View/download PDF
44. The use of microarray and other multiplex technologies in the diagnosis of allergy.
- Author
-
Keshavarz B, Platts-Mills TAE, and Wilson JM
- Subjects
- Allergens immunology, Humans, Immunologic Tests, Technology Assessment, Biomedical, Hypersensitivity diagnosis, Hypersensitivity immunology, Immunoglobulin E immunology, Microarray Analysis methods
- Abstract
Objective: To give an overview and describe the strengths and weaknesses of immunoglobulin E (IgE) microarray and other multiplex assays that have been developed and are being used for allergy diagnostics., Data Sources: Queries for IgE microarray and multiplex assays were conducted with PubMed and Google Scholar, searching for primary articles and review papers., Study Selections: We focused on articles written in English on commercially available IgE multiplex assays that were reported in the allergy and immunology literature., Results: Several commercial IgE assays that use microarray or other multiplex technology have been developed, and some have been implemented into clinical practice in Europe and Asia, with the Immuno Solid-Phase Allergen Chip being the most widely studied. Results of these assays generally correlate with results using "singleplex" IgE assays (eg, ImmunoCAP), though there can be variability among products and among allergens. A strength of the microarray technology is that IgE to a large number of allergens can be detected simultaneously in a single test, and only a small amount of patient serum is required. Cost, inadequate sensitivity under some scenarios, and difficulties with data interpretation, in some cases of 100 or more allergens, can be limitations., Conclusion: IgE microarray assays are already a valuable tool in research applications. These assays, and also other forms of IgE multiplex assays, are likely to play an important role in the clinical practice of allergy in the future. Additional studies focused on clinical outcomes, and the development of more targeted allergen panels could facilitate increased clinical use., (Copyright © 2021 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2021
- Full Text
- View/download PDF
45. Lessons in Innate and Allergic Immunity From Dust Mite Feces and Tick Bites.
- Author
-
Keshavarz B, Erickson LD, Platts-Mills TAE, and Wilson JM
- Abstract
Allergic diseases represent a major cause of morbidity in modern industrialized and developing countries. The origins and development of allergic immune responses have proven difficult to unravel and remain an important scientific objective. House dust mites (HDM) and ticks represent two important causes of allergic disease. Investigations into HDM fecal particles and tick bites have revealed insights which have and will continue to shape our understanding of allergic immunity. In the present review, focus is given to the role of innate immunity in shaping the respective responses to HDM and ticks. The HDM fecal particle represents a rich milieu of molecules that can be recognized by pathogen-recognition receptors of the innate immune system. Factors in tick saliva and/or tissue damage resultant from tick feeding are thought to activate innate immune signaling that promotes allergic pathways. Recent evidence indicates that innate sensing involves not only the direct recognition of allergenic agents/organisms, but also indirect sensing of epithelial barrier disruption. Although fecal particles from HDM and bites from ticks represent two distinct causes of sensitization, both involve a complex array of molecules that contribute to an innate response. Identification of specific molecules will inform our understanding of the mechanisms that contribute to allergic immunity, however the key may lie in the combination of molecules delivered to specific sites in the body., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Keshavarz, Erickson, Platts-Mills and Wilson.)
- Published
- 2021
- Full Text
- View/download PDF
46. An Overview of the Relevance of IgG4 Antibodies in Allergic Disease with a Focus on Food Allergens.
- Author
-
Platts-Mills TAE, Keshavarz B, Wilson JM, Li RC, Heymann PW, Gold DR, McGowan EC, and Erwin EA
- Abstract
Antibodies of the IgG4 isotype are strongly associated with allergic disease but have several properties such as not precipitating with allergens, not activating complement and poor binding to Fcγ receptors that argue against a pro-inflammatory role. In keeping with that, IgG4 antibodies are a striking feature of the response to immunotherapy. In two naturally occurring situations IgG4 antibodies are common with low or absent IgE antibodies. The first example is children raised in a house with a cat and the second is eosinophilic esophagitis (EoE). In many population-based cohorts, the ownership of a cat in early childhood is associated with a decreased prevalence of a cat allergy at age 10. The second example (i.e., EoE) is a novel form of food allergy that is not mediated by IgE and is related to consuming cow's milk or wheat. In EoE, patients have IgG4 to milk proteins in high > 10 µg/mL or very high > 100 µg/mL titers. Enigmatically these patients are found to have deposits of IgG4 in the wall of their inflamed esophagus. The factors that have given rise to EoE remain unclear; however, changes in food processing over the past 50 years, particularly ultra-heat treatment and the high pressure homogenization of milk, represent a logical hypothesis.
- Published
- 2021
- Full Text
- View/download PDF
47. Characterizing viscoelastic properties of synthetic and natural fibers and their coatings with a torsional pendulum.
- Author
-
Keshavarz B, Zarket B, Amin S, Rughani R, Muthukrishnan S, Holten-Andersen N, and McKinley GH
- Abstract
Characterizing and understanding the viscoelastic mechanical properties of natural and synthetic fibers is of great importance in many biological and industrial applications. Microscopic techniques such as micro/nano indentation have been successfully employed in such efforts, yet these tests are often challenging to perform on fibers and come with certain limitations in the interpretation of the obtained results within the context of the macroscopic viscoelasticity in the fiber. Here we instead explore the properties of a series of natural and synthetic fibers, using a freely-oscillating torsional pendulum. The torsional oscillation of the damped mass-fiber system is precisely recorded with a simple HD video-camera and an image processing algorithm is used to analyze the resulting videos. Analysis of the processed images show a viscoelastic damped oscillatory response and a simple mechanical model describes the amplitude decay of the oscillation data very well. The natural frequency of the oscillation and the corresponding damping ratio can be extracted using a logarithmic decrement method and directly connected to the bulk viscoelastic properties of the fiber. We further study the sensitivity of these measurements to changes in the chemo-mechanical properties of the outer coating layers on one of the synthetic fibers. To quantify the accuracy of our measurements with the torsional pendulum, a complementary series of tests are also performed on a strain-controlled rheometer in both torsional and tensile deformation modes.
- Published
- 2021
- Full Text
- View/download PDF
48. The role of cognitive factors and personality traits in the perception of illusory self-motion (vection).
- Author
-
D'Amour S, Harris LR, Berti S, and Keshavarz B
- Subjects
- Adult, Cognition, Humans, Motion, Personality, Illusions, Motion Perception
- Abstract
Vection is a perceptual phenomenon that describes the visually induced subjective sensation of self-motion in the absence of physical motion. Previous research has discussed the potential involvement of top-down cognitive mechanisms on vection. Here, we quantified how cognitive manipulations such as contextual information (i.e., expectation) and plausibility (i.e., chair configuration) alter vection. We also explored how individual traits such as field dependence, depersonalization, anxiety, and social desirability might be related to vection. Fifty-one healthy adults were exposed to an optic flow stimulus that consisted of horizontally moving black-and-white bars presented on three adjacent monitors to generate circular vection. Participants were divided into three groups and given experimental instructions designed to induce either strong, weak, or no expectation with regard to the intensity of vection. In addition, the configuration of the chair (rotatable or fixed) was modified during the experiment. Vection onset time, duration, and intensity were recorded. Results showed that expectation altered vection intensity, but only when the chair was in the rotatable configuration. Positive correlations for vection measures with field dependence and depersonalization, but no sex-related effects were found. Our results show that vection can be altered by cognitive factors and that individual traits can affect the perception of vection, suggesting that vection is not a purely perceptual phenomenon, but can also be affected by top-down mechanisms.
- Published
- 2021
- Full Text
- View/download PDF
49. Time-connectivity superposition and the gel/glass duality of weak colloidal gels.
- Author
-
Keshavarz B, Rodrigues DG, Champenois JB, Frith MG, Ilavsky J, Geri M, Divoux T, McKinley GH, and Poulesquen A
- Abstract
Colloidal gels result from the aggregation of Brownian particles suspended in a solvent. Gelation is induced by attractive interactions between individual particles that drive the formation of clusters, which in turn aggregate to form a space-spanning structure. We study this process in aluminosilicate colloidal gels through time-resolved structural and mechanical spectroscopy. Using the time-connectivity superposition principle a series of rapidly acquired linear viscoelastic spectra, measured throughout the gelation process by applying an exponential chirp protocol, are rescaled onto a universal master curve that spans over eight orders of magnitude in reduced frequency. This analysis reveals that the underlying relaxation time spectrum of the colloidal gel is symmetric in time with power-law tails characterized by a single exponent that is set at the gel point. The microstructural mechanical network has a dual character; at short length scales and fast times it appears glassy, whereas at longer times and larger scales it is gel-like. These results can be captured by a simple three-parameter constitutive model and demonstrate that the microstructure of a mature colloidal gel bears the residual skeleton of the original sample-spanning network that is created at the gel point. Our conclusions are confirmed by applying the same technique to another well-known colloidal gel system composed of attractive silica nanoparticles. The results illustrate the power of the time-connectivity superposition principle for this class of soft glassy materials and provide a compact description for the dichotomous viscoelastic nature of weak colloidal gels., Competing Interests: The authors declare no competing interest.
- Published
- 2021
- Full Text
- View/download PDF
50. α-Gal specific-IgE prevalence and levels in Ecuador and Kenya: Relation to diet, parasites, and IgG 4 .
- Author
-
Wilson JM, Keshavarz B, James HR, Retterer MKC, Schuyler AJ, Knoedler A, Workman LJ, Ng'ang'a L, Chico ME, Rönmark E, Heymann PW, Perzanowski MS, Platts-Mills TAE, and Cooper PJ
- Subjects
- Adolescent, Adult, Animals, Ascaris immunology, Ascaris isolation & purification, Child, Child, Preschool, Diet, Ecuador epidemiology, Feces parasitology, Female, Food Hypersensitivity blood, Food Hypersensitivity epidemiology, Food Hypersensitivity parasitology, Humans, Immunoglobulin E blood, Immunoglobulin G blood, Kenya epidemiology, Male, Prevalence, Red Meat, Trichuris isolation & purification, Virginia epidemiology, Young Adult, Disaccharides immunology, Food Hypersensitivity immunology, Immunoglobulin E immunology, Immunoglobulin G immunology
- Abstract
Background: IgE to α-Gal is a cause of mammalian meat allergy and has been linked to tick bites in North America, Australia, and Eurasia. Reports from the developing world indicate that α-Gal sensitization is prevalent but has been little investigated., Objective: We sought evidence for the cause(s) of α-Gal sensitization and lack of reported meat allergy among children in less developed settings in Ecuador and Kenya., Methods: IgE to α-Gal and total IgE were assessed in children from Ecuador (n = 599) and Kenya (n = 254) and compared with children with (n = 42) and without known (n = 63) mammalian meat allergy from the southeastern United States. Information on diet, potential risk factors, and helminth infections was available for children from Ecuador. IgG
4 to α-Gal and antibodies to regionally representative parasites were assessed in a subset of children., Results: In Ecuador (32%) and Kenya (54%), α-Gal specific IgE was prevalent, but levels were lower than in children with meat allergy from the United States. Sensitization was associated with rural living, antibody markers of Ascaris exposure, and total IgE, but not active infections with Ascaris or Trichuris species. In Ecuador, 87.5% reported consuming beef at least once per week, including 83.9% of those who had α-Gal specific IgE. Levels of α-Gal specific IgG4 were not high in Ecuador, but were greater than in children from the United States., Conclusions: These results suggest that in areas of the developing world with endemic parasitism, α-Gal sensitization is (1) common, (2) associated with Ascaris exposure, and (3) distinguished by a low percentage of specific/total IgE compared with individuals with meat allergy in the United States., (Copyright © 2021. Published by Elsevier Inc.)- Published
- 2021
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.