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Fulltext Closed form solutions for unsteady free convection flow of a second grade fluid over an oscillating vertical plate

Ali F, Khan I, Shafie S

PLoS One, 2014;9(2):e85099.
PMID: 24551033 DOI: 10.1371/journal.pone.0085099

Closed form solutions for unsteady free convection flows of a second grade fluid near an isothermal vertical plate oscillating in its plane using the Laplace transform technique are established. Expressions for velocity and temperature are obtained and displayed graphically for different values of Prandtl number Pr, thermal Grashof number Gr, viscoelastic parameter α, phase angle ωτ and time τ. Numerical values of skin friction τ 0 and Nusselt number Nu are shown in tables. Some well-known solutions in literature are reduced as the limiting cases of the present solutions.

Matched MeSH terms: Oscillometry/instrumentation*
Reduced dynamics of two oscillators collectively coupled to a thermal bath

Tay BA

Phys Rev E Stat Nonlin Soft Matter Phys, 2013 May;87(5):052117.
PMID: 23767497

We study the reduced dynamics of a pair of nondegenerate oscillators coupled collectively to a thermal bath. The model is related to the trilinear boson model where the idler mode is promoted to a field. Due to nonlinear coupling, the Markovian master equation for the pair of oscillators admits non-Gaussian equilibrium states, where the modes distribute according to the Bose-Einstein statistics. These states are metastable before the nonlinear coupling is taken over by linear coupling between the individual oscillators and the field. The Gibbs state for the individual modes lies in the subspace with infinite occupation quantum number. We present the time evolution of a few states to illustrate the behaviors of the system.

Matched MeSH terms: Oscillometry/methods*
Investigation on the effect of EDFA location in ring cavity Brillouin-Erbium fiber laser

Hambali NA, Mahdi MA, Al-Mansoori MH, Abas AF, Saripan MI

Opt Express, 2009 Jul 06;17(14):11768-75.
PMID: 19582091

We have investigated the characteristics of Brillouin-Erbium fiber laser (BEFL) with variation of Erbium-doped fiber amplifier (EDFA) locations in a ring cavity configuration. Three possible locations of the EDFA in the laser cavity have been studied. The experimental results show that the location of EDFA plays vital role in determining the output power and the tuning range. Besides the Erbium gain, Brillouin gain also contributes to the performance of the BEFL. By placing the EDFA next to the Brillouin gain medium (dispersion compensating fiber), the Brillouin pump signal is amplified thereby generating higher intensities of Brillouin Stokes line. This efficient process suppresses the free running self-lasing cavity modes from oscillating in cavity as a result of higher Stokes laser power and thus provide a wider tuning range. At the injected Brillouin pump power of 1.6 mW and the maximum 1480 nm pump power of 135 mW, the maximum Stokes laser power of 25.1 mW was measured and a tuning range of 50 nm without any self-lasing cavity modes was obtained.

Matched MeSH terms: Oscillometry/methods
Circadian and solar clocks interact in seasonal flowering

Yeang HY

Bioessays, 2009 Nov;31(11):1211-8.
PMID: 19795408 DOI: 10.1002/bies.200900078

The plant maintains a 24-h circadian cycle that controls the sequential activation of many physiological and developmental functions. There is empirical evidence suggesting that two types of circadian rhythms exist. Some plant rhythms appear to be set by the light transition at dawn, and are calibrated to circadian (zeitgeber) time, which is measured from sunrise. Other rhythms are set by both dawn and dusk, and are calibrated to solar time that is measured from mid-day. Rhythms on circadian timing shift seasonally in tandem with the timing of dawn that occurs earlier in summer and later in winter. On the other hand, rhythms set to solar time are maintained independently of the season, the timing of noon being constant year-round. Various rhythms that run in-phase and out-of-phase with one another seasonally may provide a means to time and induce seasonal events such as flowering.

Matched MeSH terms: Oscillometry/methods
Fulltext Comparative study of popular objective functions for damping power system oscillations in multimachine system

Islam NN, Hannan MA, Shareef H, Mohamed A, Salam MA

ScientificWorldJournal, 2014;2014:549094.
PMID: 24977210 DOI: 10.1155/2014/549094

Power oscillation damping controller is designed in linearized model with heuristic optimization techniques. Selection of the objective function is very crucial for damping controller design by optimization algorithms. In this research, comparative analysis has been carried out to evaluate the effectiveness of popular objective functions used in power system oscillation damping. Two-stage lead-lag damping controller by means of power system stabilizers is optimized using differential search algorithm for different objective functions. Linearized model simulations are performed to compare the dominant mode's performance and then the nonlinear model is continued to evaluate the damping performance over power system oscillations. All the simulations are conducted in two-area four-machine power system to bring a detailed analysis. Investigated results proved that multiobjective D-shaped function is an effective objective function in terms of moving unstable and lightly damped electromechanical modes into stable region. Thus, D-shape function ultimately improves overall system damping and concurrently enhances power system reliability.

Matched MeSH terms: Oscillometry/instrumentation; Oscillometry/methods*
Correlation between impulse oscillometry with bronchodilator reversibility in asthmatic population in a tertiary referral centre

Mas Fazlin MJ, Ching ZH, Azat AA, Mohamed Faisal AH

Med J Malaysia, 2024 Jan;79(1):21-27.
PMID: 38287753

INTRODUCTION: Spirometry is considered as a 'gold standard' for diagnosis of asthma. Impulse oscillometry (IOS) is an alternative diagnostic tool which requires less cooperation by the participants. We performed a study to determine the correlation of IOS with bronchodilator reversibility from spirometry in asthmatic participants. We studied the correlation between forced expiratory flow (FEF25%-75%) and differences between the resistance at 5Hz and 20Hz (R5-R20) in small airway disease (SAD) and the proportion of SAD diagnosed using IOS.
MATERIALS AND METHODS: This was a cross-sectional study involving 82 asthmatic participants in Hospital Canselor Tuanku Muhriz (HCTM), Universiti Kebangsaan Malaysia (UKM) conducted between December 2020 till January 2022. Participants performed pre- and post-bronchodilator IOS and spirometry within the same day. Correlation between spirometry and IOS parameters and FEF25%-75% with IOS were determined and analysed.
RESULTS: The change of forced expiratory volume in 1 second (FEV1) was statistically correlated with a change of R5 in IOS. A decrement of 14.5% in R5 can be correlated with positive bronchodilator response (BDR) with a sensitivity of 63.9% and specificity of 60.9%, p=0.007. Pre-bronchodilator FEF25%-75% correlated with all parameters of SAD in IOS, e.g., R5-R20, reactance at 5Hz (X5) and area of reactance (AX), p < 0.05. IOS detection for SAD is higher compared to FEF25%-75% in the BDR negative group (91.3% vs 58.7%).
CONCLUSION: IOS detected both bronchodilator reversibility and SAD hence can be considered as an alternative tool to spirometry for diagnosis of asthma in adults. IOS detected SAD more than FEF25%-75%, especially in BDR-negative group.

Matched MeSH terms: Oscillometry
Fulltext Surface plasmon resonance sensing detection of mercury and lead ions based on conducting polymer composite

Abdi MM, Abdullah LC, Sadrolhosseini AR, Mat Yunus WM, Moksin MM, Tahir PM

PLoS One, 2011;6(9):e24578.
PMID: 21931763 DOI: 10.1371/journal.pone.0024578

A new sensing area for a sensor based on surface plasmon resonance (SPR) was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI) conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU) were obtained for PPy-CHI film due to a specific binding of chitosan with Pb(2+) and Hg(2+) ions. The Pb(2+) ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb(2+) compared to Hg(2+). The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.

Matched MeSH terms: Oscillometry/methods
Mode-locked thulium-bismuth codoped fiber laser using graphene saturable absorber in ring cavity

Zen DI, Saidin N, Damanhuri SS, Harun SW, Ahmad H, Ismail MA, et al.

Appl Opt, 2013 Feb 20;52(6):1226-9.
PMID: 23434993 DOI: 10.1364/AO.52.001226

We demonstrate mode locking of a thulium-bismuth codoped fiber laser (TBFL) operating at 1901.6 nm, using a graphene-based saturable absorber (SA). In this work, a single layer graphene is mechanically exfoliated using the scotch tape method and directly transferred onto the surface of a fiber pigtail to fabricate the SA. The obtained Raman spectrum characteristic indicates that the graphene on the core surface has a single layer. At 1552 nm pump power of 869 mW, the mode-locked TBFL self starts to generate an optical pulse train with a repetition rate of 16.7 MHz and pulse width of 0.37 ps. This is a simple, low-cost, stable, and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required, such as sensing and biomedical diagnostics.

Matched MeSH terms: Oscillometry/methods
Fulltext Improved Measurement of Blood Pressure by Extraction of Characteristic Features from the Cuff Oscillometric Waveform

Lim PK, Ng SC, Jassim WA, Redmond SJ, Zilany M, Avolio A, et al.

Sensors (Basel), 2015 Jun 16;15(6):14142-61.
PMID: 26087370 DOI: 10.3390/s150614142

We present a novel approach to improve the estimation of systolic (SBP) and diastolic blood pressure (DBP) from oscillometric waveform data using variable characteristic ratios between SBP and DBP with mean arterial pressure (MAP). This was verified in 25 healthy subjects, aged 28 ± 5 years. The multiple linear regression (MLR) and support vector regression (SVR) models were used to examine the relationship between the SBP and the DBP ratio with ten features extracted from the oscillometric waveform envelope (OWE). An automatic algorithm based on relative changes in the cuff pressure and neighbouring oscillometric pulses was proposed to remove outlier points caused by movement artifacts. Substantial reduction in the mean and standard deviation of the blood pressure estimation errors were obtained upon artifact removal. Using the sequential forward floating selection (SFFS) approach, we were able to achieve a significant reduction in the mean and standard deviation of differences between the estimated SBP values and the reference scoring (MLR: mean ± SD = -0.3 ± 5.8 mmHg; SVR and -0.6 ± 5.4 mmHg) with only two features, i.e., Ratio2 and Area3, as compared to the conventional maximum amplitude algorithm (MAA) method (mean ± SD = -1.6 ± 8.6 mmHg). Comparing the performance of both MLR and SVR models, our results showed that the MLR model was able to achieve comparable performance to that of the SVR model despite its simplicity.

Matched MeSH terms: Oscillometry/methods*
Fulltext Characterization of structural stability of palm oil esters-based nanocosmeceuticals loaded with tocotrienol

Ng SH, Woi PM, Basri M, Ismail Z

J Nanobiotechnology, 2013;11:27.
PMID: 24059593 DOI: 10.1186/1477-3155-11-27

Palm oil esters (POEs) are esters derived from palm oil and oleyl alcohol have great potential in the cosmetic and pharmaceutical industries due to the excellent wetting behavior of the esters without the oily feel. The role of oil-in-water nanoemulsions loaded with tocotrienol sedimentation behavior was studied. LUMiFuge® 116 particle separation analyzer was used to investigate the sedimentation behavior of POEs/tocotrienol/xanthan gum nanoemulsion system during centrifugation. Analyzing the sedimentation kinetics of dispersions in a centrifugal field also yields information about the rheological behavior and structural stability.

Matched MeSH terms: Oscillometry
Generalized variable projective synchronization of time delayed systems

Banerjee S, Theesar SJ, Kurths J

Chaos, 2013 Mar;23(1):013118.
PMID: 23556955 DOI: 10.1063/1.4791589

We study generalized variable projective synchronization between two unified time delayed systems with constant and modulated time delays. A novel Krasovskii-Lyapunov functional is constructed and a generalized sufficient condition for synchronization is derived analytically using the Lyapunov stability theory and adaptive techniques. The proposed scheme is valid for a system of n-numbers of first order delay differential equations. Finally, a new neural oscillator is considered as a numerical example to show the effectiveness of the proposed scheme.

Matched MeSH terms: Oscillometry
Some observations on the mechanics of oscillation of ultrasonic files

Ahmad M

Endod Dent Traumatol, 1990 Feb;6(1):12-5.
PMID: 2202589

The resonant characteristics of ultrasonic files driven by the Cavi-Endo unit were examined. The investigation was carried out by evaluating the pattern of oscillation and the power emitted by the ultrasonic files. It was observed that the files oscillated in a sinusoidal fashion, exhibiting a standing wave pattern along the file. The power emitted was found to be directly proportional to the flexibility of the file. Such behaviour is typical of a system that exhibits resonance.

Matched MeSH terms: Oscillometry
Fulltext Biomedical engineer's guide to the clinical aspects of intensive care mechanical ventilation

Major VJ, Chiew YS, Shaw GM, Chase JG

Biomed Eng Online, 2018 Nov 12;17(1):169.
PMID: 30419903 DOI: 10.1186/s12938-018-0599-9

BACKGROUND: Mechanical ventilation is an essential therapy to support critically ill respiratory failure patients. Current standards of care consist of generalised approaches, such as the use of positive end expiratory pressure to inspired oxygen fraction (PEEP-FiO2) tables, which fail to account for the inter- and intra-patient variability between and within patients. The benefits of higher or lower tidal volume, PEEP, and other settings are highly debated and no consensus has been reached. Moreover, clinicians implicitly account for patient-specific factors such as disease condition and progression as they manually titrate ventilator settings. Hence, care is highly variable and potentially often non-optimal. These conditions create a situation that could benefit greatly from an engineered approach. The overall goal is a review of ventilation that is accessible to both clinicians and engineers, to bridge the divide between the two fields and enable collaboration to improve patient care and outcomes. This review does not take the form of a typical systematic review. Instead, it defines the standard terminology and introduces key clinical and biomedical measurements before introducing the key clinical studies and their influence in clinical practice which in turn flows into the needs and requirements around how biomedical engineering research can play a role in improving care. Given the significant clinical research to date and its impact on this complex area of care, this review thus provides a tutorial introduction around the review of the state of the art relevant to a biomedical engineering perspective.
DISCUSSION: This review presents the significant clinical aspects and variables of ventilation management, the potential risks associated with suboptimal ventilation management, and a review of the major recent attempts to improve ventilation in the context of these variables. The unique aspect of this review is a focus on these key elements relevant to engineering new approaches. In particular, the need for ventilation strategies which consider, and directly account for, the significant differences in patient condition, disease etiology, and progression within patients is demonstrated with the subsequent requirement for optimal ventilation strategies to titrate for patient- and time-specific conditions.
CONCLUSION: Engineered, protective lung strategies that can directly account for and manage inter- and intra-patient variability thus offer great potential to improve both individual care, as well as cohort clinical outcomes.

Matched MeSH terms: Oscillometry