Artículos de revistas: "FFRP"

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Wang, Xian y Li. "Effects of Fiber Surface Grafting with Nano-Clay on the Hydrothermal Ageing Behaviors of Flax Fiber/Epoxy Composite Plates". Polymers 11, n.º 8 (31 de julio de 2019): 1278. http://dx.doi.org/10.3390/polym11081278.

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Flax fiber has high sensitivity to moisture, and moisture uptake leads to the decrease of mechanical properties and distortion in shape. This paper attempts to graft flax fabric with nano-clay, with assistance from a silane-coupling agent, in order to improve hygrothermal resistance. The nano-clay grafted flax fabric reinforced epoxy (FFRP) composite produced through vacuum assisted resin infusion (VARI) process were subjected to 80% RH chamber for 12 weeks at 20, 40 and 70 °C, respectively. Moisture uptake, dimensional stability, and tensile properties was studied as a function of humidity exposure. Through SEM and FTIR, the effects of hygrothermal exposure was elucidated. In comparison to control FFRP plates, nano-clay grafting decreases saturation moisture uptake and the coefficient of diffusion of FFRP by 38.4% and 13.2%, respectively. After exposure for six weeks, the retention rate of the tensile modulus of the nano-clay grafted flax fiber based FFRP increased by 33.8% compared with that of the control ones. Nano-clay grafting also reduces the linear moisture expansion coefficient of FFRPs by 8.4% in a radial direction and 10.9% in a weft direction.

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Yan, Libo, Nawawi Chouw y Bohumil Kasal. "Experimental study and numerical simulation on bond between FFRP and CFRC components". Journal of Reinforced Plastics and Composites 36, n.º 4 (13 de diciembre de 2016): 305–20. http://dx.doi.org/10.1177/0731684416683453.

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Natural flax fabric-reinforced polymer (FFRP) tube encased coir fibre-reinforced concrete (CFRC) structure (termed as FFRP-CFRC) is steel-free hybrid structure that has shown its potential as axial, flexural and earthquake-resistant structural members. An FFRP plate with a CFRC overlay has great potential to be light and environmentally friendly wall panel or pedestrian bridge deck. The overall structural performance of this panel or deck is highly dependent on the bond at the FFRP and CFRC interface. Therefore, this study proposed a novel interlocking at their interface to improve the bond and thus the composite action of the hybrid structures composed of FFRP and CFRC components. This interlocking was generated by creating numbers of perforations on the FFRP component (tube and plate) surface. To evaluate the effectiveness of using this interlocking on the bond behaviour between FFRP and CFRC, two stages experimental studies were conducted. In the first stage, 18 FFRP-CFRC cylindrical specimens were constructed and tested under push-out bond, bending and axial compression. In the second stage, 30 FFRP plate and CFRC sandwich block specimens were constructed and tested under push-out bond considering different experimental parameters, i.e. depth, diameter and number of perforations. Additionally, numerical simulation was performed to verify the failure modes of FFRP plate and CFRC sandwich blocks under push-out. This study revealed that the presence of interlocking is an effective way to improve the interfacial bond and composite action between FFRP (either tube or plate) and CFRC components.

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Yan, Li Bo, Nawawi Chouw y Krishnan Jayaraman. "Experimental Investigation of Flax FRP Tube Confined Coconut Fibre Reinforced Concrete". Key Engineering Materials 594-595 (diciembre de 2013): 416–20. http://dx.doi.org/10.4028/www.scientific.net/kem.594-595.416.

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The compressive and flexural performance of flax fibre reinforced polymer (FFRP) confined coconut fibre reinforced concrete (CFRC) structures were investigated. The mass content of coconut fibre considered was 1% of cement. Eighteen cylinders were tested under uniaxial compression and 12 beams were tested under four-point bending. Test results show that in compression, both FFRP tube and FFRP wrapping confinements enhance the axial compressive strength and ultimate strain of concrete significantly, e.g. the ultimate strength of 4-layer FFRP tube confined CFRC is 94% larger than that of the unconfined CFRC. In flexure, the FFRP tube increases the lateral load bearing capacity and the deflection several times larger than the unconfined concrete columns, e.g. the ultimate lateral load of 4-layer FFRP confined PC and CFRC are 1066% and 946% larger than the corresponding unconfined PC and CFRC specimens. In flexure, coir inclusion can affect the failure mode of the FFRP-CFRC composite structure significantly.

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4

Wang y Petrů. "Effect of Hygrothermal Aging and Surface Treatment on the Dynamic Mechanical Behavior of Flax Fiber Reinforced Composites". Materials 12, n.º 15 (25 de julio de 2019): 2376. http://dx.doi.org/10.3390/ma12152376.

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The recent developments of FRP (fiber reinforced polymer) are towards the growth and usage of natural FRP in the field of engineering due to both environmental and economic benefits. Flax fiber is one of the most commonly used natural fibers. One of the critical factors affecting the mechanical behavior of FFRP (flax fiber reinforced polymer) is hygrothermal aging. Some experimental works have been conducted to investigate the effect of hydrothermal aging on static behavior of FFRP. However, fewer efforts have been made to study its damping properties after hydrothermal aging. In this paper, the effect of surface treatment (including alkalization, silanization, acetylation and alkali-silanization) on dynamic mechanical behavior of FFRP under hygrothermal aging is studied. The results show that water resistance and damping properties of FFRP are improved after surface treatment. The acetylation treated FFRP exhibits excellent damping performance among all treated specimens.

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Bachtiar, Erik Valentine, Katarzyna Kurkowiak, Libo Yan, Bohumil Kasal y Torsten Kolb. "Thermal Stability, Fire Performance, and Mechanical Properties of Natural Fibre Fabric-Reinforced Polymer Composites with Different Fire Retardants". Polymers 11, n.º 4 (16 de abril de 2019): 699. http://dx.doi.org/10.3390/polym11040699.

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In this study, ammonium polyphosphate (APP) and aluminum hydroxide (ALH) with different mass contents were used as fire retardants (FRs) on plant-based natural flax fabric-reinforced polymer (FFRP) composites. Thermogravimetric analysis (TGA), limited oxygen index (LOI), and the Underwriters Laboratories (UL)-94 horizontal and vertical tests were carried out for evaluating the effectiveness of these FR treatments. Flat-coupon tensile test was performed to evaluate the effects of FR treatment on the mechanical properties of the FFRP composites. For both fire retardants, the results showed that the temperature of the thermal decomposition and the LOI values of the composites increased as the FR content increases. Under the UL-94 vertical test, the FFRP composites with 20% and 30% APP (i.e., by mass content of epoxy polymer matrix) were self-extinguished within 30 and 10 s following the removal of the flame without any burning drops, respectively. However, the mechanical tensile tests showed that the APP treated FFRP composites reduced their elastic modulus and strength up to 24% and 18%, respectively. Scanning electronic microscopic (SEM) for morphology examination showed an effective coating of the flax fibres with the FRs, which improved the flame retardancy of the treated composites.

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Yan, Weian, Hassen Riahi, Karim Benzarti, Robert Chlela, Laurence Curtil y David Bigaud. "Durability and Reliability Estimation of Flax Fiber Reinforced Composites Using Tweedie Exponential Dispersion Degradation Process". Mathematical Problems in Engineering 2021 (9 de febrero de 2021): 1–21. http://dx.doi.org/10.1155/2021/6629637.

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Flax fiber reinforced composites are demonstrating promising outcomes which make them potential candidates to replace synthetic composites in various industrial applications. However, there is limited information regarding their long-term performance, and it is usually acknowledged that natural fibers are less resistant than their synthetic counterparts. In this context, it is crucial to study their durability before considering their use for structural rehabilitation and strengthening in construction. This research aims to study and predict the performance of flax fiber reinforced polymer (FFRP) composites with a biobased epoxy matrix. The test program consists in exposing FFRP laminates and FFRP strengthened concrete slabs to different accelerated ageing conditions over a total period of two years. In the present study, not a single stress variable but various combinations and coupling of two environmental stress variables, temperature (T) and relative humidity (RH), are considered, thereby distinguishing this study from most of the works reported in the literature. Then, a series of mechanical destructive tests are performed periodically on aged samples to evaluate property evolutions over ageing time. The collected experimental data are analyzed to develop a performance evolution model and to evaluate the service lifetime performance of this new biobased FFRP composite. For that, the potential of the Tweedie exponential dispersion (TED) process model, which takes some famous stochastic processes (Wiener process, Gamma process, and inverse Gaussian process) as special cases, is investigated. The TED process modeling, particularly interesting in the cases of complicated degradation mechanisms, is written here for destructive tests and, finally, a reliability analysis based on the TED process model determined is carried out in order to update the FRP design equations provided by international codes in the specific case of FFRP.

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Mak, Kenneth y Amir Fam. "Performance of SiO2-impregnated flax fibre reinforced polymers under wet dry and freeze thaw cycles". Journal of Composite Materials 55, n.º 2 (5 de agosto de 2020): 251–63. http://dx.doi.org/10.1177/0021998320946811.

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Flax fibres are of growing interest as a reinforcing fibre; however, they are susceptible to moisture and have demonstrated poor bond to conventional hydrophobic resins. Although there are multiple approaches to address these issues, research has heavily focused on their short-term performance. In this research program, the performance of flax fibre reinforced polymer (FFRP), manufactured using SiO2-impregnated flax fibre, is assessed for its short-term performance as well as its long-term performance when exposed to wet-dry (WD) and freeze-thaw (FT) cycles. Treated FFRP showed improved bond between the fibre and resin as well as resistance to fibre pull-out. It exhibited a tensile strength of 144 ± 15 MPa and a tensile modulus of 8.6 ± 0.35 GPa. When exposed to WD cycles, delamination between the fibre and resin were observed. The onset of statistically significant mechanical damage occurred after four WD cycles, with a final 3% reduction in strength and a 6% reduction in modulus post-exposure. When exposed to FT cycles, FFRP experienced cracking within the fibre, as well as delamination at the interface. The onset of statistically significant mechanical damage occurred after 50 FT cycles, which manifested as a final 5% reduction in tensile strength and 10% reduction in tensile modulus post-exposure. Regardless of treatment, FFRP demonstrated the same damage mechanisms as untreated variants.

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SUZUKI, Masashi, Naoki AMANO y Hideaki KOIKE. "The DNA-binding domain of feast/famine regulatory protein, FFRP." Proceedings of the Japan Academy, Series B 79B, n.º 3 (2003): 92–98. http://dx.doi.org/10.2183/pjab.79b.92.

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Zhang, Zhang, Shigeho Takarada y Sabee Molloi. "Quantification of absolute coronary flow reserve and relative fractional flow reserve in a swine animal model using angiographic image data". American Journal of Physiology-Heart and Circulatory Physiology 303, n.º 3 (1 de agosto de 2012): H401—H410. http://dx.doi.org/10.1152/ajpheart.00153.2012.

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Coronary flow reserve (CFR) and fractional flow reserve (FFR) are important physiological indexes for coronary disease. The purpose of this study was to validate the CFR and FFR measurement techniques using only angiographic image data. Fifteen swine were instrumented with an ultrasound flow probe on the left anterior descending artery (LAD). Microspheres were gradually injected into the LAD to create microvascular disruption. An occluder was used to produce stenosis. Contrast material injections were made into the left coronary artery during image acquisition. Volumetric blood flow from the flow probe (Q̇q) was continuously recorded. Angiography-based blood flow (Q̇a) was calculated by using a time-density curve based on the first-pass analysis technique. Flow probe-based CFR (CFRq) and angiography-based CFR (CFRa) were calculated as the ratio of hyperemic to baseline flow using Q̇q and Q̇a, respectively. Relative angiographic FFR (relative FFRa) was calculated as the ratio of the normalized Q̇a in LAD to the left circumflex artery (LCX) during hyperemia. Flow probe-based FFR (FFRq) was measured from the ratio of hyperemic flow with and without disease. CFRa showed a strong correlation with the gold standard CFRq (CFRa = 0.91 CFRq + 0.30; r = 0.90; P < 0.0001). Relative FFRa correlated linearly with FFRq (relative FFRa = 0.86 FFRq + 0.05; r = 0.90; P < 0.0001). The quantification of CFR and relative FFRa using angiographic image data was validated in a swine model. This angiographic technique can potentially be used for coronary physiological assessment during routine cardiac catheterization.

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Wang, Wenjie y Nawawi Chouw. "Flexural behaviour of FFRP wrapped CFRC beams under static and impact loadings". International Journal of Impact Engineering 111 (enero de 2018): 46–54. http://dx.doi.org/10.1016/j.ijimpeng.2017.08.010.

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Wang, Wenjie y Nawawi Chouw. "Behaviour of CFRC beams strengthened by FFRP laminates under static and impact loadings". Construction and Building Materials 155 (noviembre de 2017): 956–64. http://dx.doi.org/10.1016/j.conbuildmat.2017.08.031.

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12

Takai, Y., T. Kaneta, R. Iwata, S. Frumoto, Y. Ishikawa, M. Tsujitani, S. Yamada, H. Yasuda, E. Nakata y S. Maruoka. "1000 POSTER [18]FFRP-170: A novel hypoxia maker for PET: Initial clinical data for the usefulness and the correlation between tumor response to radiotherapy and [18]FFRP-170 uptake". European Journal of Cancer Supplements 5, n.º 4 (septiembre de 2007): 135. http://dx.doi.org/10.1016/s1359-6349(07)70595-5.

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KOIKE, Hideaki, Katsushi YOKOYAMA, Tsuyoshi KAWASHIMA, Tomoko YAMASAKI, Shin-ichi MAKINO, Lester CLOWNEY y Masashi SUZUKI. "GATC Methylation by Dam methylase in archaea: its roles and possible transcription regulation by an FFRP". Proceedings of the Japan Academy, Series B 81, n.º 7 (2005): 278–90. http://dx.doi.org/10.2183/pjab.81.278.

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Faheem, Muhammad, Rizwan Aslam Butt, Basit Raza, Hani Alquhayz, Muhammad Waqar Ashraf, Saleem Raza y MD Asri Bin Ngadi. "FFRP: Dynamic Firefly Mating Optimization Inspired Energy Efficient Routing Protocol for Internet of Underwater Wireless Sensor Networks". IEEE Access 8 (2020): 39587–604. http://dx.doi.org/10.1109/access.2020.2976105.

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Scully, Jason, Anne Moudon, Philip Hurvitz, Anju Aggarwal y Adam Drewnowski. "A Time-Based Objective Measure of Exposure to the Food Environment". International Journal of Environmental Research and Public Health 16, n.º 7 (2 de abril de 2019): 1180. http://dx.doi.org/10.3390/ijerph16071180.

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Exposure to food environments has mainly been limited to counting food outlets near participants’ homes. This study considers food environment exposures in time and space using global positioning systems (GPS) records and fast food restaurants (FFRs) as the environment of interest. Data came from 412 participants (median participant age of 45) in the Seattle Obesity Study II who completed a survey, wore GPS receivers, and filled out travel logs for seven days. FFR locations were obtained from Public Health Seattle King County and geocoded. Exposure was conceptualized as contact between stressors (FFRs) and receptors (participants’ mobility records from GPS data) using four proximities: 21 m, 100 m, 500 m, and ½ mile. Measures included count of proximal FFRs, time duration in proximity to ≥1 FFR, and time duration in proximity to FFRs weighted by FFR counts. Self-reported exposures (FFR visits) were excluded from these measures. Logistic regressions tested associations between one or more reported FFR visits and the three exposure measures at the four proximities. Time spent in proximity to an FFR was associated with significantly higher odds of FFR visits at all proximities. Weighted duration also showed positive associations with FFR visits at 21-m and 100-m proximities. FFR counts were not associated with FFR visits. Duration of exposure helps measure the relationship between the food environment, mobility patterns, and health behaviors. The stronger associations between exposure and outcome found at closer proximities (<100 m) need further research.

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Wang, Bachtiar, Yan, Kasal y Fiore. "Flax, Basalt, E-Glass FRP and Their Hybrid FRP Strengthened Wood Beams: An Experimental Study". Polymers 11, n.º 8 (29 de julio de 2019): 1255. http://dx.doi.org/10.3390/polym11081255.

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In this study, the structural behavior of small-scale wood beams externally strengthened with various fiber strengthened polymer (FRP) composites (i.e., flax FRP (FFRP), basalt FRP (BFRP), E-glass FRP (“E” stands for electrical resistance, GFRP) and their hybrid FRP composites (HFRP) with different fiber configurations) were investigated. FRP strengthened wood specimens were tested under bending and the effects of different fiber materials, thicknesses and the layer arrangements of the FRP on the flexural behavior of strengthened wood beams were discussed. The beams strengthened with flax FRP showed a higher flexural loading capacity in comparison to the beams with basalt FRP. Flax FRP provided a comparable enhancement in the maximum load with beams strengthened with glass FRP at the same number of FRP layers. In addition, all the hybrid FRPs (i.e., a combination of flax, basalt and E-glass FRP) in this study exhibited no significant enhancement in load carrying capacity but larger maximum deflection than the single type of FRP composite. It was also found that the failure modes of FRP strengthened beams changed from tensile failure to FRP debonding as their maximum bending load increased.

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ISHIJIMA, Sanae A., Lester CLOWNEY, Hideaki KOIKE y Masashi SUZUKI. "An electron microscopic study of the archaeal feast/famine regulatory protein 2. Crystal formation by a full length FFRP, pot0434017 (FL11)". Proceedings of the Japan Academy, Series B 80, n.º 1 (2004): 22–27. http://dx.doi.org/10.2183/pjab.80.22.

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YOKOYAMA, Katsushi, Sonomi EBIHARA, Tomoko KIKUCHI y Masashi SUZUKI. "Binding of the feast/famine regulatory protein (FFRP) FL11 (pot0434017) to DNA in the "promoter to coding" region of gene fl11". Proceedings of the Japan Academy, Series B 81, n.º 2 (2005): 64–75. http://dx.doi.org/10.2183/pjab.81.64.

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White-Schwoch, Travis, Samira Anderson, Jennifer Krizman, Trent Nicol y Nina Kraus. "Case studies in neuroscience: subcortical origins of the frequency-following response". Journal of Neurophysiology 122, n.º 2 (1 de agosto de 2019): 844–48. http://dx.doi.org/10.1152/jn.00112.2019.

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The auditory frequency-following response (FFR) reflects synchronized and phase-locked activity along the auditory pathway in response to sound. Although FFRs were historically thought to reflect subcortical activity, recent evidence suggests an auditory cortex contribution as well. Here we present electrophysiological evidence for the FFR’s origins from two cases: a patient with bilateral auditory cortex lesions and a patient with auditory neuropathy, a condition of subcortical origin. The patient with auditory cortex lesions had robust and replicable FFRs, but no cortical responses. In contrast, the patient with auditory neuropathy had no FFR despite robust and replicable cortical responses. This double dissociation shows that subcortical synchrony is necessary and sufficient to generate an FFR. NEW & NOTEWORTHY The frequency-following response (FFR) reflects synchronized and phase-locked neural activity in response to sound. The authors present a dual case study, comparing FFRs and cortical potentials between a patient with auditory neuropathy (a condition of subcortical origin) and a patient with bilateral auditory cortex lesions. They show that subcortical synchrony is necessary and sufficient to generate an FFR.

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Ordin, Mikhail y Ineke Mennen. "Cross-Linguistic Differences in Bilinguals' Fundamental Frequency Ranges". Journal of Speech, Language, and Hearing Research 60, n.º 6 (10 de junio de 2017): 1493–506. http://dx.doi.org/10.1044/2016_jslhr-s-16-0315.

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Purpose We investigated cross-linguistic differences in fundamental frequency range (FFR) in Welsh-English bilingual speech. This is the first study that reports gender-specific behavior in switching FFRs across languages in bilingual speech. Method FFR was conceptualized as a behavioral pattern using measures of span (range of fundamental frequency—in semitones—covered by the speaker's voice) and level (overall height of fundamental frequency maxima, minima, and means of speaker's voice) in each language. Results FFR measures were taken from recordings of 30 Welsh-English bilinguals (14 women and 16 men), who read 70 semantically matched sentences, 35 in each language. Comparisons were made within speakers across languages, separately in male and female speech. Language background and language use information was elicited for qualitative analysis of extralinguistic factors that might affect the FFR. Conclusions Cross-linguistic differences in FFR were found to be consistent across female bilinguals but random across male bilinguals. Most female bilinguals showed distinct FFRs for each language. Most male bilinguals, however, were found not to change their FFR when switching languages. Those who did change used different strategies than women when differentiating FFRs between languages. Detected cross-linguistic differences in FFR can be explained by sociocultural factors. Therefore, sociolinguistic factors are to be taken into account in any further study of language-specific pitch setting and cross-linguistic differences in FFR.

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Bergman, Michael S., Dennis J. Viscusi, Brian K. Heimbuch, Joseph D. Wander, Anthony R. Sambol y Ronald E. Shaffer. "Evaluation of Multiple (3-Cycle) Decontamination Processing for Filtering Facepiece Respirators". Journal of Engineered Fibers and Fabrics 5, n.º 4 (diciembre de 2010): 155892501000500. http://dx.doi.org/10.1177/155892501000500405.

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Disposable N95 filtering facepiece respirators (FFRs) certified by the National Institute for Occupational Safety and Health (NIOSH) are widely used by healthcare workers to reduce exposures to infectious biological aerosols. There is currently major concern among public health officials about a possible shortage of N95 FFRs during an influenza pandemic. Decontamination and reuse of FFRs is a possible strategy for extending FFR supplies in an emergency; however, the NIOSH respirator certification process does not currently include provisions for decontamination and reuse. Recent studies have investigated the laboratory performance (filter aerosol penetration and filter airflow resistance) and physical integrity of FFRs following one-cycle (1X) processing of various decontamination treatments. The studies found that a single application of some methods did not adversely affect laboratory performance. In the event that healthcare facilities experience dramatic shortages of FFR supplies, multiple decontamination processing may become necessary. This study investigates three-cycle (3X) processing of eight different methods: ultraviolet germicidal irradiation, ethylene oxide, hydrogen peroxide gas plasma, hydrogen peroxide vapor, microwave-oven-generated steam, bleach, liquid hydrogen peroxide, and moist heat incubation (pasteurization). A four-hour 3X submersion of FFR in deionized water was performed for comparison (control). Following 3X treatment by each decontamination and control method, FFRs were evaluated for changes in physical appearance, odor, and laboratory filtration performance. Only the hydrogen peroxide gas plasma treatment resulted in mean penetration levels > 5% for four of the six FFR models; FFRs treated by the seven other methods and the control samples had expected levels of filter aerosol penetration (< 5%) and filter airflow resistance. Physical damage varied by treatment method. Further research is still needed before any specific decontamination methods can be recommended.

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Seligman, Henry, Matthew J. Shun-Shin, Anushkumar Vasireddy, Christopher Cook, Yousif Y. Ahmad, James Howard, Sayan Sen et al. "Fractional flow reserve derived from microcatheters versus standard pressure wires: a stenosis-level meta-analysis". Open Heart 6, n.º 1 (marzo de 2019): e000971. http://dx.doi.org/10.1136/openhrt-2018-000971.

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AimsTo determine the agreement between sensor-tipped microcatheter (MC) and pressure wire (PW)-derived fractional flow reserve (FFR).Methods and resultsStudies comparing FFR obtained from MC (FFRMC, Navvus Microcatheter System, ACIST Medical Systems, Eden Prairie, Minnesota, USA) versus standard PW (FFRPW) were identified, and a meta-analysis of numerical and categorical agreement was performed. The relative levels of drift and device failure of MC and PW systems from each study were assessed. Six studies with 440 lesions (413 patients) were included. The mean overall bias between FFRMC and FFRPW was −0.029 (FFRMC lower). Bias and variance were greater for lesions with lower FFRPW (p<0.001). Using a cut-off of 0.80, 18 % of lesions were reclassified by FFRMC versus FFRPW (with 15 % being false positives). The difference in reported drift between FFRPW and FFRMC was small. Device failure was more common with MC than PW (7.1% vs 2%).ConclusionFFRMC systematically overestimates lesion severity, with increased bias in more severe lesions. Using FFRMC changes revascularisation guidance in approximately one out of every five cases. PW drift was similar between systems. Device failure was higher with MC.

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Fisher, Edward M., Aaron W. Richardson, Shannon D. Harpest, Kent C. Hofacre y Ronald E. Shaffer. "Reaerosolization of MS2 Bacteriophage from an N95 Filtering Facepiece Respirator by Simulated Coughing". Annals of Occupational Hygiene 56, n.º 3 (29 de noviembre de 2011): 315–25. http://dx.doi.org/10.1093/annhyg/mer101.

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Abstract The supply of N95 filtering facepiece respirators (FFRs) may not be adequate to match demand during a pandemic outbreak. One possible strategy to maintain supplies in healthcare settings is to extend FFR use for multiple patient encounters; however, contaminated FFRs may serve as a source for the airborne transmission of virus particles. In this study, reaerosolization of virus particles from contaminated FFRs was examined using bacteriophage MS2 as a surrogate for airborne pathogenic viruses. MS2 was applied to FFRs as droplets or droplet nuclei. A simulated cough (370 l min−1 peak flow) provided reverse airflow through the contaminated FFR. The number and size of the reaerosolized particles were measured using gelatin filters and an Andersen Cascade Impactor (ACI). Two droplet nuclei challenges produced higher percentages of reaerosolized particles (0.21 and 0.08%) than a droplet challenge (<0.0001%). Overall, the ACI-determined size distribution of the reaerosolized particles was larger than the characterized loading virus aerosol. This study demonstrates that only a small percentage of viable MS2 viruses was reaerosolized from FFRs by reverse airflow under the conditions evaluated, suggesting that the risks of exposure due to reaerosolization associated with extended use can be considered negligible for most respiratory viruses. However, risk assessments should be updated as new viruses emerge and better workplace exposure data becomes available.

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Zhu, Jintuo, Xinjian He, Steve Guffey, Liang Wang, Haifeng Wang y Jianwei Cheng. "Performance Comparison of N95 and P100 Filtering Facepiece Respirators with Presence of Artificial Leakage". Annals of Work Exposures and Health 64, n.º 2 (30 de noviembre de 2019): 202–16. http://dx.doi.org/10.1093/annweh/wxz086.

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Abstract Objectives National Institute for Occupational Safety and Health–approved P100 filtering facepiece respirators (FFRs) have a higher filter efficiency compared to the N95 filters. However, the former typically produce higher flow resistance (Rf). Consequently, when faceseal leakage is present, the proportion of leakage airflow for P100 FFRs may exceed that of N95s, resulting in a higher total inward leakage (TIL) of the P100. Methods In this manikin-based study, the performance of two pairs of N95 and P100 FFRs (N95-A versus P100-A; N95-B versus P100-B) were compared under five sealing conditions (fully sealed and partially sealed with one, two, or three leaks of 0.8-mm, and one 2-mm leak). Sodium chloride particles (CMD ~45 nm) were used as the challenge aerosol. Respirators were tested under three constant flows (15, 50, and 85 L/min) and three cyclic flows (mean inspiratory flow = 15, 50, and 85 L/min). Both filter penetration (Pfilter) and TIL were determined. The Rf under constant flows was recorded. Based on Pfilter, TIL, and Rf, the quality factor (qf) was calculated to compare the overall performance of N95 and P100 FFRs. Results For a fully sealed condition, the Pfilter was much lower for the P100 FFRs than for the N95 FFRs. When small leaks were inserted (0.8-mm and 2 × 0.8-mm), the TIL was higher for the P100 FFRs than for the N95 FFRs under the lowest tested flow (15 L/min), while for greater leaks (3 × 0.8-mm and 2-mm), the TIL of the P100 FFRs was always higher regardless of the flow. The Rf of P100 FFRs was measured twice as high as the N95. The qf values were also found higher for the N95 FFRs than for the P100 FFRs regardless of leak size and breathing flow. Conclusions With the presence of artificial leakage, a P100 FFR with high-flow-resistance may not be as protective as a low-flow-resistance N95 FFR. This finding suggests that future efforts should be directed to reducing the breathing resistance when designing P100 FFRs.

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Harnish, Delbert A., Brian K. Heimbuch, Michael Husband, April E. Lumley, Kimberly Kinney, Ronald E. Shaffer y Joseph D. Wander. "Challenge of N95 Filtering Facepiece Respirators with Viable H1N1 Influenza Aerosols". Infection Control & Hospital Epidemiology 34, n.º 5 (mayo de 2013): 494–99. http://dx.doi.org/10.1086/670225.

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Objective.Specification of appropriate personal protective equipment for respiratory protection against influenza is somewhat controversial. In a clinical environment, N95 filtering facepiece respirators (FFRs) are often recommended for respiratory protection against infectious aerosols. This study evaluates the ability of N95 FFRs to capture viable H1N1 influenza aerosols.Methods.Five N95 FFR models were challenged with aerosolized viable H1N1 influenza and inert polystyrene latex particles at continuous flow rates of 85 and 170 liters per minute. Virus was assayed using Madin-Darby canine kidney cells to determine the median tissue culture infective dose (TCID50). Aerosols were generated using a Collison nebulizer containing H1N1 influenza virus at 1 × 108 TCID50/mL. To determine filtration efficiency, viable sampling was performed upstream and downstream of the FFR.Results.N95 FFRs filtered 0.8-μm particles of both H1N1 influenza and inert origins with more than 95% efficiency. With the exception of 1 model, no statistically significant difference in filtration performance was observed between influenza and inert particles of similar size. Although statistically significant differences were observed for 2 models when comparing the 2 flow rates, the differences have no significance to protection.Conclusions.This study empirically demonstrates that a National Institute for Occupational Safety and Health-approved N95 FFR captures viable H1N1 influenza aerosols as well as or better than its N95 rating, suggesting that a properly fitted FFR reduces inhalation exposure to airborne influenza virus. This study also provides evidence that filtration efficiency is based primarily on particle size rather than the nature of the particle's origin.

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Wilson, James R. y Ananthanarayan Krishnan. "Human Frequency-Following Responses to Binaural Masking Level Difference Stimuli". Journal of the American Academy of Audiology 16, n.º 03 (marzo de 2005): 184–95. http://dx.doi.org/10.3766/jaaa.16.3.6.

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Binaural masking level difference is the behavioral threshold difference between a diotic condition (SoNo) and a dichotic condition with a 180° interaural phase delay of either the signal (SπNo) or the masker (SoNπ). Threshold disparity is partially related to coincidence-detecting units in the medial superior olive that are sensitive to low-frequency binaural stimuli with interaural phase differences. Previous surface evoked potential studies report significant latency and amplitude differences to SπNo stimuli with respect to SoNo stimuli in the P1-N1 auditory event related potential, but no study has reported physiologic masking level differences in a brain stem evoked potential. The human frequency-following response (FFR) represents activity from low-frequency, phase locking neural units in the upper brainstem. Unmasked FFRs to 500 Hz tone bursts and masked FFRs using a 1.5 kHz low-pass masker were recorded from nine normal-hearing adult subjects. Significant reduction in FFR amplitude occurred in the SoNo condition, re the So condition, with masker intensities near the psychoacoustic SoNo masking level. Significant FFR amplitude recovery was observed for both the SoNπ and SπNo conditions. These results support the role of phase-locked neural activity in brainstem mechanisms involved in perceptual masking release.

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Schnell, Eric, Elham Karamooz, Melanie J. Harriff, Jane E. Yates, Christopher D. Pfeiffer y Stephen M. Smith. "Construction and validation of an ultraviolet germicidal irradiation system using locally available components". PLOS ONE 16, n.º 7 (23 de julio de 2021): e0255123. http://dx.doi.org/10.1371/journal.pone.0255123.

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Coronavirus disease (COVID-19), the disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, is responsible for a global pandemic characterized by high transmissibility and morbidity. Healthcare workers (HCWs) are at risk of contracting COVID-19, but this risk has been mitigated through the use of personal protective equipment such as N95 Filtering Facepiece Respirators (FFRs). At times the high demand for FFRs has exceeded supply, placing HCWs at increased exposure risk. Effective FFR decontamination of many FFR models using ultraviolet-C germicidal irradiation (UVGI) has been well-described, and could maintain respiratory protection for HCWs in the face of supply line shortages. Here, we detail the construction of an ultraviolet-C germicidal irradiation (UVGI) device using previously existing components available at our institution. We provide data on UV-C dosage delivered with our version of this device, provide information on how users can validate the UV-C dose delivered in similarly constructed systems, and describe a simple, novel methodology to test its germicidal effectiveness using in-house reagents and equipment. As similar components are readily available in many hospitals and industrial facilities, we provide recommendations on the local construction of these systems, as well as guidance and strategies towards successful institutional implementation of FFR decontamination.

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Yokoyama, K., H. Koike, S. A. Ishijima, L. Clowney, T. Kikuchi y M. Suzuki. "2P101 Structure and function of feast/famine regulatory proteins : 3.interaction between the FL11 protein and the fl11 promoter". Seibutsu Butsuri 44, supplement (2004): S135. http://dx.doi.org/10.2142/biophys.44.s135_1.

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Galbraith, Gary C. y John M. Kane. "Brainstem Frequency-Following Responses and Cortical Event-Related Potentials during Attention". Perceptual and Motor Skills 76, n.º 3_suppl (junio de 1993): 1231–41. http://dx.doi.org/10.2466/pms.1993.76.3c.1231.

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Human brainstem frequency-following responses (FFRs) and cortical event-related potentials (ERPs) were evoked by a low-frequency (230 Hz) tone during directed attention. ERPs showed significant amplitude differences consistent with expected attention effects, viz., largest to attended stimuli and smallest to ignored stimuli. The ERP data thereby confirm that attention effectively modulated cortical responses. The FFR, however, did not differ between conditions. The present results agree with one earlier FFR study and a majority of studies using click stimuli to elicit the brainstem auditory evoked response (BAER). However, several BAER studies and two recent FFR studies have shown that attention can influence human brainstem responses. The present results are therefore interpreted in the context of specific task requirements that optimize early selective attention effects.

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Krizman, Jennifer, Tory Lindley, Silvia Bonacina, Danielle Colegrove, Travis White-Schwoch y Nina Kraus. "Play Sports for a Quieter Brain: Evidence From Division I Collegiate Athletes". Sports Health: A Multidisciplinary Approach 12, n.º 2 (9 de diciembre de 2019): 154–58. http://dx.doi.org/10.1177/1941738119892275.

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Background: Playing sports has many benefits, including boosting physical, cardiovascular, and mental fitness. We tested whether athletic benefits extend to sensory processing—specifically auditory processing—as measured by the frequency-following response (FFR), a scalp-recorded electrophysiological potential that captures neural activity predominately from the auditory midbrain to complex sounds. Hypothesis: Given that FFR amplitude is sensitive to experience, with enrichment enhancing FFRs and injury reducing them, we hypothesized that playing sports is a form of enrichment that results in greater FFR amplitude. Study Design: Cross-sectional study. Level of Evidence: Level 3. Methods: We measured FFRs to the speech syllable “da” in 495 student-athletes across 19 Division I teams and 493 age- and sex-matched controls and compared them on 3 measures of FFR amplitude: amplitude of the response, amplitude of the background noise, and the ratio of these 2 measures. Results: Athletes have larger responses to sound than nonathletes, driven by a reduction in their level of background neural noise. Conclusion: These findings suggest that playing sports increases the gain of an auditory signal by turning down the background noise. This mode of enhancement may be tied to the overall fitness level of athletes and/or the heightened need of an athlete to engage with and respond to auditory stimuli during competition. Clinical Relevance: These results motivate athletics overall and engagement in athletic interventions for populations that struggle with sensory processing, such as individuals with language disorders. Also, because head injuries can disrupt these same auditory processes, it is important to consider how auditory processing enhancements may offset injury.

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Yang, Jie. "Measurement and Feature Analysis of Plantar Pressure Center in Athletes under Different Exercise Modes". Instrumentation Mesure Métrologie 19, n.º 5 (15 de noviembre de 2020): 399–403. http://dx.doi.org/10.18280/i2m.190511.

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Walking and running, two essential exercises in daily training for athletes, are major causes to foot injuries. The plantar pressure center (PPC) can accurately reflect the gait process, and effectively measure the function of foot. This paper measures the PPC trajectories of a total of 45 athletes during the support period of walking and running, and analyzes their regularities under different exercise modes. The time percentage of PPC trajectory and foot progression angle were selected as the main observation indices. The support period under each exercise mode was divided into four phases: the initial contact phase (ICP), the forefoot contact phase (FFCP), the foot flat phase (FFP), and the forefoot push off phase (FFPOP). The statistical analysis shows that: Under the running mode, the time of the heel landing on the ground and the relative load on the heel decrease with the growing speed. Under the same exercise mode, the left and right feet differ slightly in the PPC trajectory; the foot progression angle peaks in FFPOP and minimizes in FFP. In ICP and FFPOP, the foot progression angle under running is smaller than that under walking; in FFP and FFCP, the foot progression angle under running is larger than that under walking. The research results provide the scientific basis for the reasonable arrangement of athlete training.

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Clinard, Christopher G. y Kelly L. Tremblay. "Aging Degrades the Neural Encoding of Simple and Complex Sounds in the Human Brainstem". Journal of the American Academy of Audiology 24, n.º 07 (julio de 2013): 590–99. http://dx.doi.org/10.3766/jaaa.24.7.7.

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Background: Older adults, with or without normal peripheral hearing sensitivity, have difficulty understanding speech. This impaired speech perception may, in part, be due to desynchronization affecting the neural representation of acoustic features. Here we determine if phase-locked neural activity generating the brainstem frequency-following response (FFR) exhibits age-related desynchronization and how this degradation affects the neural representation of simple and complex sounds. Purpose: The objectives of this study were to (1) characterize the effects of age on the neural representation of simple tones and complex consonant-vowel stimuli, (2) determine if sustained and transient components of the FFR are differentially affected by age, and (3) determine if the inability to encode a simple signal predicts degradation in representation for complex speech signals. Research Design: Correlational Study Sample: Thirty four adults (aged 22–77 yr) with hearing thresholds falling within normal limits. Data Collection and Analysis: Stimuli used to evoke FFRs were 1000 Hz tone bursts as well as a consonant-vowel /da/ sound. Results: The neural representation of simple (tone) and complex (/da/) stimuli declines with advancing age. Tone-FFR phase coherence decreased as chronological age increased. For the consonant-vowel FFRs, transient onset and offset response amplitudes were smaller, and offset responses were delayed with age. Sustained responses at the onset of vowel periodicity were prolonged in latency and smaller in amplitude as age increased. FFT amplitude of the consonant-vowel FFR fundamental frequency did not significantly decline with increasing age. The ability to encode a simple signal was related to degradation in the neural representation of a complex, speechlike sound. Tone-FFR phase coherence was significantly related to the later vowel response components but not the earlier vowel components. Conclusions: FFR components representing the tone and consonant-vowel /da/ stimulus were negatively affected by age, showing age-related reductions in response synchrony and amplitude, as well as prolonged latencies. These aging effects were evident in middle age, even in the absence of significant hearing loss.

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Huh, Yu Jung, Hye Min Jeong, Juhye Lim, Ha Yan Park, Min Young Kim, Hong Sang Oh y Kyungmin Huh. "Fit Characteristics of N95 Filtering Facepiece Respirators and the Accuracy of the User Seal Check among Koreans". Infection Control & Hospital Epidemiology 39, n.º 1 (enero de 2018): 104–7. http://dx.doi.org/10.1017/ice.2017.271.

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Adequate facepiece fit of N95 filtering facepiece respirators (FFRs) is crucial for optimal protection against airborne pathogens. The quantitative fit test (QNFT) pass rates of the 4 N95 FFR models commonly used in Korea were below 50%. Male sex was identified as a single independent predictive factor for QNFT pass.Infect Control Hosp Epidemiol 2018;39:104–107

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Bidelman, Gavin M. "Objective Information-Theoretic Algorithm for Detecting Brainstem-Evoked Responses to Complex Stimuli". Journal of the American Academy of Audiology 25, n.º 08 (septiembre de 2014): 715–26. http://dx.doi.org/10.3766/jaaa.25.8.2.

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Background: The scalp-recorded frequency-following response (FFR), an auditory-evoked potential with putative neural generators in the rostral brainstem, provides a robust representation of the neurophysiologic encoding of complex stimuli. The FFR is rapidly becoming a valuable tool for understanding the neural transcription of speech and music, language-related processing disorders, and brain plasticity at initial stages of the auditory pathway. Despite its potential clinical and empirical utility, determining the presence of a response is still dependent on the subjective interpretation by an experimenter/clinician. Purpose: The purpose of the present work was to develop and validate a fully objective procedure for the automatic detection of FFRs elicited by complex auditory stimuli, including speech. Research Design: Mutual information (MI) was computed between the spectrographic representation of neural FFRs and their evoking acoustic stimuli to quantify the amount of shared time-frequency information between electrophysiologic responses and stimulus acoustics. To remove human subjectivity associated with typical response evaluation, FFRs were first simulated at known signal-to-noise ratios using a computational model of the auditory periphery. The MI at which model FFRs contained +3 dB Signal-to-noise ratio was taken as the criterion threshold (θMI) for the presence of a response. θMI was then applied as a binary classifier on actual neurophysiologic responses recorded previously in human participants (n = 35). Sham recordings, in which no stimulus was presented to participants, allowed us to determine the receiver operating characteristics of the MI metric and the capabilities of the algorithm to segregate true evoked responses from sham recordings. Results: Results showed high overall accuracy (93%) in the metric’s ability to identify true responses from sham recordings. The metric’s overall performance was considerably better than trained human observers who, on average, accurately identified only ˜75% of the true neural responses. Complementary results were found in the metric’s receiver operating characteristic test performance characteristics with a sensitivity and specificity of 97% and 85%, respectively. Additionally, MI increased monotonically and was asymptotic with increasing trials (i.e., sweeps) contributing to the averaged FFR and, thus, can be used as a stopping criteria for signal averaging. Conclusions: The present results demonstrate that the mutual information between a complex acoustic stimulus and its corresponding brainstem response can provide a completely objective and robust method for automated FFR detection. Application of the MI metric to evoked potential speech audiometry testing may provide clinicians with a more robust tool to quantitatively evaluate the presence and quality of speech-evoked brainstem responses ultimately minimizing subjective interpretation and human error.

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Paul, Diptanu, Ayush Gupta y Anand Kumar Maurya. "Exploring options for reprocessing of N95 Filtering Facepiece Respirators (N95-FFRs) amidst COVID-19 pandemic: A systematic review". PLOS ONE 15, n.º 11 (20 de noviembre de 2020): e0242474. http://dx.doi.org/10.1371/journal.pone.0242474.

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Background There is global shortage of Personal Protective Equipment due to COVID-19 pandemic. N95 Filtering Facepiece Respirators (N95-FFRs) provide respiratory protection against respiratory pathogens including SARS-CoV-2. There is scant literature on reprocessing methods which can enable reuse of N95-FFRs. Aim We conducted this study to evaluate research done, prior to COVID-19 pandemic, on various decontamination methods for reprocessing of N95-FFRs. Methods We searched 5 electronic databases (Pubmed, Google Scholar, Crossref, Ovid, ScienceDirect) and 1 Grey literature database (OpenGrey). We included original studies, published prior to year 2020, which had evaluated any decontamination method on FFRs. Studies had evaluated a reprocessing method against parameters namely physical changes, user acceptability, respirator fit, filter efficiency, microbicidal efficacy and presence of chemical residues post-reprocessing. Findings and conclusions Overall, we found 7887 records amongst which 17 original research articles were finally included for qualitative analysis. Overall, 21 different types of decontamination or reprocessing methods for N95-FFRs were evaluated. Most commonly evaluated method for reprocessing of FFRs was Ultraviolet (Type-C) irradiation (UVGI) which was evaluated in 13/17 (76%) studies. We found published literature was scant on this topic despite warning signs of pandemic of a respiratory illness over the years. Promising technologies requiring expeditious evaluation are UVGI, Microwave generated steam (MGS) and based on Hydrogen peroxide vapor. Global presence of technologies, which have been given Emergency use authorisation for N95-FFR reprocessing, is extremely limited. Reprocessing of N95-FFRs by MGS should be considered for emergency implementation in resource limited settings to tackle shortage of N95-FFRs. Systematic review identifier PROSPERO, PROSPERO ID: CRD42020189684, (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020189684).

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Zhang, Jun-Mei, Gaurav Chandola, Ru-San Tan, Ping Chai, Lynette L. S. Teo, Ris Low, John Carson Allen et al. "Quantification of effects of mean blood pressure and left ventricular mass on noninvasive fast fractional flow reserve". American Journal of Physiology-Heart and Circulatory Physiology 319, n.º 2 (1 de agosto de 2020): H360—H369. http://dx.doi.org/10.1152/ajpheart.00135.2020.

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While brachial mean blood pressure (MBP) and left ventricular mass (LVM) measured from CTCA are the two CFD simulation input parameters, their effects on noninvasive fractional flow reserve (FFRB) have not been systematically investigated. We demonstrate that inaccurate MBP and LVM inputs differing from patient-specific values could result in misclassification of borderline ischemic lesions. This is important in the clinical application of noninvasive FFR in coronary artery disease diagnosis.

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Ferreira, Laís, Piotr Henryk Skarzynski, Magdalena Beata Skarzynska, Milaine Dominici Sanfins y Eliara Pinto Vieira Biaggio. "Effect of Auditory Maturation on the Encoding of a Speech Syllable in the First Days of Life". Brain Sciences 11, n.º 7 (25 de junio de 2021): 844. http://dx.doi.org/10.3390/brainsci11070844.

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(1) Background: In neonates and infants, the physiological modifications associated with language development are reflected in their Frequency Following Responses (FFRs) in the first few months of life. (2) Objective: This study aimed to test the FFRs of infants in the first 45 days of life in order to evaluate how auditory maturation affects the encoding of a speech syllable. (3) Method: In total, 80 healthy, normal-hearing infants, aged 3 to 45 days old, participated in this study. The sample was divided into three groups: GI, 38 neonates from 3 to 15 days; GII, 25 infants from 16 to 30 days; and GIII, 17 infants from 31 to 45 days. All participants underwent FFR testing. Results: With age, there was a decrease in the latency of all FFR waves, with statistically significant differences among the groups studied for waves V, A, E, F, and O. The mean amplitudes showed an increase, with a statistically significant difference only for wave V. The slope measure increased over the 45 days, with a statistically significant difference between GIII and GI and between GIII and GII. (4) Conclusions: The encoding of a speech sound changes with auditory maturation over the first 45 days of an infant’s life.

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Okrasa, Małgorzata, Justyna Szulc, Agnieszka Brochocka y Beata Gutarowska. "Application of Olfactometry to Assess the Anti-Odor Properties of Filtering Facepiece Respirators Containing Activated Carbon Nonwovens". International Journal of Environmental Research and Public Health 18, n.º 15 (1 de agosto de 2021): 8157. http://dx.doi.org/10.3390/ijerph18158157.

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Filtering facepiece respirators (FFR) with anti-odor properties are used to reduce odor nuisance occurring both in everyday life and at workplaces. Unfortunately, there are no standardized methods to measure the efficiency of odor reduction of such personal protective devices. This paper aims to determine whether olfactometric-based methods, commonly used in environmental studies, can be employed for this purpose. The proposed procedure is based on the detection of n-butanol by study participants, and it consists of three subsequent stages: (i) defining the individual levels of odor sensitivity of each study participant; (ii) determining THE odor detection level while using FFRs with varying anti-odor properties; and (iii) completing a questionnaire concerning the subjective perceptions of study participants. As a measure of odor reduction efficiency, a coefficient W, defined as a quotient of the degree of odor reduction by the FFR, and the individual odor sensitivity of the subject, was proposed. The experimental results showed the ability of our measure to differentiate the effectiveness of odor reduction of tested FFRs. This indicates that it can be potentially employed as the assessment tool to confirm the effectiveness of such respiratory protective devices as a control measure mitigating the adverse effects of malodors on workers’ health, cognition, and behavior.

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Lo, Ernest, Leon Menezes y Ryo Torii. "Impact of Inflow Boundary Conditions on the Calculation of CT-Based FFR". Fluids 4, n.º 2 (28 de marzo de 2019): 60. http://dx.doi.org/10.3390/fluids4020060.

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Background: Calculation of fractional flow reserve (FFR) using computed tomography (CT)-based 3D anatomical models and computational fluid dynamics (CFD) has become a common method to non-invasively assess the functional severity of atherosclerotic narrowing in coronary arteries. We examined the impact of various inflow boundary conditions on computation of FFR to shed light on the requirements for inflow boundary conditions to ensure model representation. Methods: Three-dimensional anatomical models of coronary arteries for four patients with mild to severe stenosis were reconstructed from CT images. FFR and its commonly-used alternatives were derived using the models and CFD. A combination of four types of inflow boundary conditions (BC) was employed: pulsatile, steady, patient-specific and population average. Results: The maximum difference of FFR between pulsatile and steady inflow conditions was 0.02 (2.4%), approximately at a level similar to a reported uncertainty level of clinical FFR measurement (3–4%). The flow with steady BC appeared to represent well the diastolic phase of pulsatile flow, where FFR is measured. Though the difference between patient-specific and population average BCs affected the flow more, the maximum discrepancy of FFR was 0.07 (8.3%), despite the patient-specific inflow of one patient being nearly twice as the population average. Conclusions: In the patients investigated, the type of inflow boundary condition, especially flow pulsatility, does not have a significant impact on computed FFRs in narrowed coronary arteries.

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Koike, H., S. A. Ishijima, M. Sakuma, K. Minahiro y M. Suzuki. "2P100 Structure and function of feast/famine regulatory proteins : 2. Interacton of DM1 with ligands studied using a crystal structure". Seibutsu Butsuri 44, supplement (2004): S134. http://dx.doi.org/10.2142/biophys.44.s134_4.

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Paramonov, Yuri, Sergey Tretyakov y Maris Hauka. "Inspection Program Development for an Aircraft Fleet and an Airline on the Basis of the Acceptance Fatigue Test Result". Transport and Telecommunication Journal 16, n.º 1 (28 de febrero de 2015): 1–8. http://dx.doi.org/10.1515/ttj-2015-0001.

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Abstract An inspection interval planning is considered in order to limit the probability of any fatigue failure (FFP) in a fleet of N aircraft (AC) and to provide an economical effectiveness of airline (AL) under the limitation of fatigue failure rate (FFR). A solution of these two problems is based on the processing of the result of acceptance fatigue test of a new type of aircraft. During this test an estimate of the parameter ϴ, of a fatigue crack growth trajectory has been obtained. If the result of this acceptance test is too bad then this new type of aircraft will not be used in service. A redesign of this project should be done. If the result the acceptance test is pretty good then the reliability of the aircraft fleet and the airline will be provided without inspections. For this strategy there is a maximum of FFP (a maximum of FFR) as a function of an unknown parameter ᶿ. This maximum can be limited by the use of the offered here procedure of the choice of the inspection number. The economic effectiveness of the AL operation is considered using the theory of Markov process with rewords.

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Van Loon, Joren, Lore Veelaert, Sander Van Goethem, Regan Watts, Stijn Verwulgen, Jouke C. Verlinden y Els Du Bois. "Reuse of Filtering Facepiece Respirators in the COVID-19 Era". Sustainability 13, n.º 2 (15 de enero de 2021): 797. http://dx.doi.org/10.3390/su13020797.

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The current COVID-19 pandemic has resulted in an immense and unforeseen increase in demand for personal protective equipment (PPE) for healthcare workers worldwide. Amongst other products, respirator masks are crucial to protect the users against transmission of the virus. Decontamination and reuse of the existing stock could be a solution to the shortage of new respirators. Based upon existing studies, it was found that (I) a solid quality control method is essential to test product reuse, (II) in-depth evaluation of the different parts of the filtering facepiece respirator (FFR) should be considered, and (III) communication of the reuse cycle is essential to take track of the amount of reuse, as this is limited to ensure quality. The goal of this paper is two-fold. First, we identify the impact of decontamination on the different parts of the FFRs and how the quality control should be performed. Two different types of FFRs are analysed within this paper, resulting in the recommendation of combining quantitative respirator mask fit testing with a thorough sensory evaluation of decontaminated FFRs to qualify them for reuse. Secondly, the possibilities of communication of this reuse to the eventual user are mapped through in-depth reasoning.

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Richard, Céline, Mary Lauren Neel, Arnaud Jeanvoine, Sharon Mc Connell, Alison Gehred y Nathalie L. Maitre. "Characteristics of the Frequency-Following Response to Speech in Neonates and Potential Applicability in Clinical Practice: A Systematic Review". Journal of Speech, Language, and Hearing Research 63, n.º 5 (22 de mayo de 2020): 1618–35. http://dx.doi.org/10.1044/2020_jslhr-19-00322.

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Purpose We sought to critically analyze and evaluate published evidence regarding feasibility and clinical potential for predicting neurodevelopmental outcomes of the frequency-following responses (FFRs) to speech recordings in neonates (birth to 28 days). Method A systematic search of MeSH terms in the Cumulative Index to Nursing and Allied HealthLiterature, Embase, Google Scholar, Ovid Medline (R) and E-Pub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily, Web of Science, SCOPUS, COCHRANE Library, and ClinicalTrials.gov was performed. Manual review of all items identified in the search was performed by two independent reviewers. Articles were evaluated based on the level of methodological quality and evidence according to the RTI item bank. Results Seven articles met inclusion criteria. None of the included studies reported neurodevelopmental outcomes past 3 months of age. Quality of the evidence ranged from moderate to high. Protocol variations were frequent. Conclusions Based on this systematic review, the FFR to speech can capture both temporal and spectral acoustic features in neonates. It can accurately be recorded in a fast and easy manner at the infant's bedside. However, at this time, further studies are needed to identify and validate which FFR features could be incorporated as an addition to standard evaluation of infant sound processing evaluation in subcortico-cortical networks. This review identifies the need for further research focused on identifying specific features of the neonatal FFRs, those with predictive value for early childhood outcomes to help guide targeted early speech and hearing interventions.

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Mulieri, Louis A., Marc D. Tischler, Barbara J. Martin, Bruce J. Leavitt, Frank P. Ittleman, Norman R. Alpert y Martin M. LeWinter. "Regional differences in the force-frequency relation of human left ventricular myocardium in mitral regurgitation: implications for ventricular shape". American Journal of Physiology-Heart and Circulatory Physiology 288, n.º 5 (mayo de 2005): H2185—H2191. http://dx.doi.org/10.1152/ajpheart.00905.2003.

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Sphericalization of the left ventricular (LV) chamber shape in patients with mitral regurgitation (MR) contributes to increased LV wall stress and energy consumption. On the basis of previous observations, we hypothesized the existence of regional differences in the force-frequency relation (FFR) within the LV that may contribute to its shape. Accordingly, in the present study, we assessed regional variation in the FFR in patients undergoing surgery for chronic, nonischemic MR with class II–III heart failure symptoms and related our findings to the in vivo LV shape. FFRs (steady-state isometric twitches, 0.2–3.4 Hz, 37°C) were evaluated in MR myocardium from the LV subepicardial free wall (MR-FW) and papillary muscle (MR-PM) and from the subepicardial free wall in coronary artery bypass graft patients with normal LV contraction patterns [nonfailing (NF)]. Ascending slope, optimal stimulation frequency, and maximal twitch tension of the FFR were depressed in MR-FW and MR-PM compared with NF ( P < 0.05). FFR depression was greater in MR-PM than in MR-FW. Between 107 and 134 beats/min, twitch tension became weaker in MR-PM, whereas it increased in MR-FW. Elevation of intracellular cAMP with forskolin eliminated FFR depression in MR-FW but not in MR-PM. MR-PM also had a 35% lower myosin heavy chain content and slowed twitch kinetics. In MR patients, the echocardiographic end-diastolic LV shape (end-diastolic eccentricity index = long axis/short axis) correlated with the ratio of ascending FFR slopes such that the end-diastolic eccentricity index increased 10% per 15% increase in slope ratio ( r = 0.88, P = 0.01). These regional differences in the frequency dependence of contractility between the free wall and papillary myocardium may contribute to changes in LV shape in MR as well as during exercise.

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Rouhbakhsh, Nematollah, John Mahdi, Jacob Hwo, Baran Nobel y Fati Mousave. "Human Frequency Following Response Correlates of Spatial Release From Masking". Journal of Speech, Language, and Hearing Research 62, n.º 11 (22 de noviembre de 2019): 4165–78. http://dx.doi.org/10.1044/2019_jslhr-h-18-0353.

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Purpose Speech recognition in complex listening environments is enhanced by the extent of spatial separation between the speech source and background competing sources, an effect known as spatial release from masking (SRM). The aim of this study was to investigate whether the phase-locked neural activity in the central auditory pathways, reflected in the frequency following response (FFR), exhibits SRM. Method Eighteen normal-hearing adults (8 men and 10 women, ranging in age from 20 to 42 years) with no known neurological disorders participated in this study. FFRs were recorded from the participants in response to a target vowel /u/ presented with spatially colocated and separated competing talkers at 3 ranges of signal-to-noise ratios (SNRs), with median SNRs of −5.4, 0.5, and 6.8 dB and for different attentional conditions (attention and no attention). Results Amplitude of the FFR at the fundamental frequency was significantly larger in the spatially separated condition as compared to the colocated condition for only the lowest (< −2.4 dB SNR) of the 3 SNR ranges tested. A significant effect of attention was found when subjects were actively focusing on the target stimuli. No significant interaction effects were found between spatial separation and attention. Conclusions The enhanced representation of the target stimulus in the separated condition suggests that the temporal pattern of phase-locked brainstem neural activity generating the FFR may contain information relevant to the binaural processes underlying SRM but only in challenging listening environments. Attention may modulate FFR fundamental frequency amplitude but does not seem to modulate spatial processing at the level of generating the FFR. Supplemental Material https://doi.org/10.23641/asha.9992597

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Roeckner, Jared T., Nevena Krstić, Bradley H. Sipe y Sarah G. Običan. "N95 Filtering Facepiece Respirator Use during Pregnancy: A Systematic Review". American Journal of Perinatology 37, n.º 10 (21 de mayo de 2020): 995–1001. http://dx.doi.org/10.1055/s-0040-1712475.

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Objective This study was aimed to systematically review the use of filtering facepiece respirators, such asN95 masks, during pregnancy. Study Design A comprehensive search for primary literature using Medline, Embase, Scopus, Web of Science, and ClinicalTrials.gov was conducted from inception until April 2020 to find articles reporting outcomes of pregnant women using filtering facepiece respirator (FFR). Studies were selected if they included the use of FFR in pregnant women and reported an outcome of interest including physiologic changes (heart rate, respiratory rate, pulse oximetry, and fetal heart rate tracing) or subjective measures (thermal or exertional discomfort or fit). The Newcastle-Ottawa Quality Assessment scale was used to assess the risk of bias. The main outcome was to describe the physiologic changes in pregnant women compared with nonpregnant women. Due to the small number of studies and heterogeneity of reported outcomes a meta-analysis was not conducted. Results of the studies were synthesized into a summary of evidence table. Results We identified four studies, three cohort studies and one crossover study, comprising 42 women using FFR during pregnancy. Risk of bias was judged to be low. Studies were consistent in showing no significant increase in maternal heart rate, respiratory rate, oxygen saturation, and fetal heart rate between pregnant and nonpregnant women using N95 FFRs for short durations. Repeat fit testing was not supported for women gaining the recommended amount of weight during pregnancy. No evidence was found to reach conclusions about prolonged N95 FFR use in pregnancy. Conclusion Limited duration N95 FFR use during pregnancy is unlikely to impart risk to the pregnant women or her fetus. Key Points

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Ishijima, S. A., H. Koike, L. Clowney, M. Tokuyoshi y M. Suzuki. "2P102 Structuer and function of feast/famine regulatory proteins : 1. 3D-Reconstruction of various assembly forms by cryo-electron microscopy". Seibutsu Butsuri 44, supplement (2004): S135. http://dx.doi.org/10.2142/biophys.44.s135_2.

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Jeng, Fuh-Cherng, Brandie Nance, Karen Montgomery-Reagan y Chia-Der Lin. "Exponential Modeling of Frequency-Following Responses in American Neonates and Adults". Journal of the American Academy of Audiology 29, n.º 02 (febrero de 2018): 125–34. http://dx.doi.org/10.3766/jaaa.16135.

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AbstractThe scalp-recorded frequency-following response (FFR) has been widely accepted in assessing the brain’s processing of speech stimuli for people who speak tonal and nontonal languages. Characteristics of scalp-recorded FFRs with increasing number of sweeps have been delineated through the use of an exponential curve-fitting model in Chinese adults; however, characteristics of speech processing for people who speak a nontonal language remain unclear.This study had two specific aims. The first was to examine the characteristics of speech processing in neonates and adults who speak a nontonal language, to evaluate the goodness of fit of an exponential model on neonatal and adult FFRs, and to determine the differences, if any, between the two groups of participants. The second aim was to assess effective recording parameters for American neonates and adults.This investigation employed a prospective between-subject study design.A total of 12 American neonates (1–3 days old) and 12 American adults (24.1 ± 2.5 yr old) were recruited. Each neonate passed an automated hearing screening at birth and all adult participants had normal hearing and were native English speakers.The English vowel /i/ with a rising pitch contour (117–166 Hz) was used to elicit the FFR. A total of 8,000 accepted sweeps were recorded from each participant. Three objective indices (Frequency Error, Tracking Accuracy, and Pitch Strength) were computed to estimate the frequency-tracking acuity and neural phase-locking magnitude when progressively more sweeps were included in the averaged waveform. For each objective index, the FFR trends were fit to an exponential curve-fitting model that included estimates of asymptotic amplitude, noise amplitude, and a time constant.Significant differences were observed between groups for Frequency Error, Tracking Accuracy, and Pitch Strength of the FFR trends. The adult participants had significantly smaller Frequency Error (p < 0.001), better Tracking Accuracy (p = 0.001), and larger Pitch Strength (p = 0.003) values than the neonate participants. The adult participants also demonstrated a faster rate of improvement (i.e., a smaller time constant) in all three objective indices compared to the neonate participants. The smaller time constants observed in adults indicate that a larger number of sweeps will be needed to adequately assess the FFR for neonates. Furthermore, the exponential curve-fitting model provided a good fit to the FFR trends with increasing number of sweeps for American neonates (mean r 2 = 0.89) and adults (mean r 2 = 0.96).Significant differences were noted between the neonatal and adult participants for Frequency Error, Tracking Accuracy, and Pitch Strength. These differences have important clinical implications in determining when to stop a recording and the number of sweeps needed to adequately assess the frequency-encoding acuity and neural phase-locking magnitude in neonates and adults. These findings lay an important foundation for establishing a normative database for American neonates and adults, and may prove to be useful in the development of diagnostic and therapeutic paradigms for neonates and adults who speak a nontonal language.

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Boonme, Kittipong, Bartlomiej Hanus, Victor R. Prybutok, Daniel A. Peak y Christopher Ryan. "Visual information influences consumer fast-food choices". Nutrition & Food Science 44, n.º 4 (8 de julio de 2014): 279–93. http://dx.doi.org/10.1108/nfs-03-2013-0036.

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Purpose – The purpose of this paper is to investigate the influence of visual information cues such as a heart icon vs the calories and fat content on the selection of healthy food in fast-food restaurants (FFRs). Design/methodology/approach – An online survey design providing a fast-food menu was implemented to collect responses from the participants. The survey respondents were recruited from a large South-western university in the USA. The research model was tested using logistic regression. Findings – Data analysis shows that visual information plays a significant role in healthy food selection in FFRs. The authors findings show that the heart icons have a statistically significant effect on food choices, while calories and fat content information did not affect the participants’ selections vs no information. Originality/value – Dietary choices and obesity are a serious social concern. This study provides support for the effect of a heart icon symbol on food choice in fast-food selection. The implication is that labelling FFR menus with symbols such as our heart icon will have a positive impact on healthy food selection vs the more usual inclusion of calorie and fat information.

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Liu, Dongxin, Shuo Wang, Qi Gao, Ruijuan Dong, Xinxing Fu, Esther Pugh y Jiong Hu. "Learning a Second Language in Adulthood Changes Subcortical Neural Encoding". Neural Plasticity 2020 (20 de octubre de 2020): 1–9. http://dx.doi.org/10.1155/2020/8836161.

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Second language learning has been shown to impact and reshape the central nervous system, anatomically and functionally. Most of the studies on second language learning and neuroplasticity have been focused on cortical areas, whereas the subcortical neural encoding mechanism and its relationship with L2 learning have not been examined extensively. The purpose of this study was to utilize frequency-following response (FFR) to examine if and how learning a tonal language in adulthood changes the subcortical neural encoding in hearing adults. Three groups of subjects were recruited: native speakers of Mandarin Chinese (native speakers (NS)), learners of the language (L2 learners), and those with no experience (native speakers of foreign languages (NSFL)). It is hypothesized that differences would exist in FFRs obtained from the three language experience groups. Results revealed that FFRs obtained from L2 learners were found to be more robust than the NSFL group, yet not on a par with the NS group. Such results may suggest that in human adulthood, subcortical neural encoding ability may be trainable with the acquisition of a new language and that neuroplasticity at the brainstem level can indeed be influenced by L2 learning.

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