Critical bounds on noise and SNR for robust estimation of real-time brain activity from functional near infra-red spectroscopy

Aqil, Muhammad,Jeong, Myung Yung Elsevier 2018 NeuroImage Vol.176 No.-

<P><B>Abstract</B></P> <P>The robust characterization of real-time brain activity carries potential for many applications. However, the contamination of measured signals by various instrumental, environmental, and physiological sources of noise introduces a substantial amount of signal variance and, consequently, challenges real-time estimation of contributions from underlying neuronal sources. Functional near infra-red spectroscopy (fNIRS) is an emerging imaging modality whose real-time potential is yet to be fully explored. The objectives of the current study are to (i) validate a time-dependent linear model of hemodynamic responses in fNIRS, and (ii) test the robustness of this approach against measurement noise (instrumental and physiological) and mis-specification of the hemodynamic response basis functions (amplitude, latency, and duration). We propose a linear hemodynamic model with time-varying parameters, which are estimated (adapted and tracked) using a dynamic recursive least square algorithm. Owing to the linear nature of the activation model, the problem of achieving robust convergence to an accurate estimation of the model parameters is recast as a problem of parameter error stability around the origin. We show that robust convergence of the proposed method is guaranteed in the presence of an acceptable degree of model misspecification and we derive an upper bound on noise under which reliable parameters can still be inferred. We also derived a lower bound on signal-to-noise-ratio over which the reliable parameters can still be inferred from a channel/voxel. Whilst here applied to fNIRS, the proposed methodology is applicable to other hemodynamic-based imaging technologies such as functional magnetic resonance imaging.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Robust real-time estimation of time-varying activity parameters. </LI> <LI> Deals with the trial-to-trial variability (noises and model misspecifications). </LI> <LI> Robust convergence of activity parameters by stabilizing their estimation error dynamics. </LI> <LI> Robustness of the proposed method is guaranteed against bounded disturbances and SNR. </LI> <LI> The permissible limits of disturbances and SNR are revealed to sustain the basic statistics. </LI> </UL> </P>

Effect of Barrier Height on the Design of Stepped Spillway using Smoothed Particle Hydrodynamics and Particle Image Velocimetry

Aqil Azman,Fei Chong Ng,Mohd. Hafiz Zawawi,Aizat Abas,Mohd. Remy Rozainy M. A. Z.,Ismail Abustan,Mohd. Nordin Adlan,Wei Loon Tam 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.2

Three-dimensional stepped spillway problems are simulated numerically using smoothed particle hydrodynamics (SPH) to visualize the flow of water along the steps and its flow dynamics. In particular, two distinct scaled-down stepped spillway models were studied with each having barrier heights of 10 mm and 25 mm, respectively. The impact of varying the height of the barrier in the design of the stepped spillway is studied in terms of it flow pattern, flow dynamics, aeration efficiency and oxygenation performances. State-of-the-art particle image velocimetry (PIV) experiment was carried out to affirm the validity of SPH findings and it turns out that both the water flow patterns attained in the SPH and PIV are quantitatively comparable. Further quantitative analysis revealed that the flow velocities in both methodologies are in great consensus. Conclusively, this has demonstrated that the capability and reliability of SPH to precisely approximate the water using finite set of particles to model the flow along the stepped spillway. Both stepped spillway configurations show nappe flow regime as the water descends down the steps. Nonetheless, vigorous hydraulic jump phenomena that is associates with the formation of turbulence and vortices is prominently observed in the configuration with larger barrier height. Decisive SPH data obtained concluded that as the barrier height increases from 10 mm to 25 mm, the water flows down the steps faster at lower pressure value and the overall aeration efficiency is improved from 1.1% to 1.2%. The usage of the higher barrier would promote the occurrence of substantial air entrainment during water swirling that will increase the power dissipation in flow. Subsequently, this while lower the power drawn to achieve the desired aeration effect. Ultimately, this study has justified the critical influence of barrier height dimension on the stepped spillway flow behavior and aeration performance.

Comparison of microbial communities during the anaerobic digestion of Gracilaria under mesophilic and thermophilic conditions

Azizi, Aqil,Kim, Wonduck,Lee, Jung Hyun Rapid Communications of Oxford Ltd in association 2016 World journal of microbiology biotechnology Vol.32 No.10

<P>Mesophilic and thermophilic anaerobic digesters (MD and TD, respectively) utilizing Gracilaria and marine sediment as the substrate and inoculum, respectively, were compared by analyzing their performances and microbial community changes. During three successive transfers, the average cumulative methane yields in the MD and TD were 222.6 +/- 17.3 mL CH4/g volatile solids (VS) and 246.1 +/- 11 mL CH4/g VS, respectively. The higher hydrolysis rate and acidogenesis in the TD resulted in a several fold greater accumulation of volatile fatty acids (acetate, propionate, and butyrate) followed by a larger pH drop with a prolonged recovery than in the MD. However, the operational stability between both digesters remained comparable. Pyrosequencing analyses revealed that the MD had more complex microbial diversity indices and microbial community changes than the TD. Interestingly, Methanomassiliicoccales, the seventh methanogen order was the predominant archaeal order in the MD along with bacterial orders of Clostridiales, Bacteriodales, and Synergistales. Meanwhile, Coprothermobacter and Methanobacteriales dominated the bacterial and archaeal community in the TD, respectively. Although the methane yield is comparable, both MD and TD show a different profile of pH, VFA and the microbial communities.</P>

The Effects of the Hot, Humid Tropical Climate and Early Age Feed Restriction on Stress and Fear Responses, and Performance in Broiler Chickens

Al-Aqil, A.,Zulkifli, I.,Sazili, A.Q.,Omar, A.R.,Rajion, M.A. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.11

The present study was conducted to determine the effects of two types of housing systems and early age feed restriction on stress and fear reactions, and performance in broiler chickens raised in a hot, humid tropical climate. On day 1, chicks were housed either in windowless environmentally controlled chambers (temperature was set at 32$^{\circ}C$ on day 1 and gradually reduced to 23$^{\circ}C$ by day 21) or in conventional open-sided houses (OH) with cyclic temperatures (minimum, 24$^{\circ}C$; maximum, 34$^{\circ}C$). An equal number of chicks from each housing system was subjected to either ad libitum feeding (AL) or 60% feed restriction on day 4, 5 and 6 (FR). The CH birds showed greater weight gain, higher feed consumption and better feed conversion ratios (FCR) than their OH counterparts. Feeding regimen had negligible effect on overall performance. Neither housing nor feeding regimen had a significant (p<0.05) effect on mortality rate. Although the CH birds were less stressed, as measured by plasma corticosterone concentration (CORT), than those of OH, the former showed longer TI duration suggesting higher magnitude of underlying fearfulness. A significant (p<0.05) effect of housing on heterophil/lymphocyte ratios was only noted among the AL birds where the CH birds had higher values than OH. Collectively, these results suggest that although OH birds had poorer performance and higher level of stress than CH, the former were less fearful. Although FR had negligible effect on growth performance, the regimen alleviated both stress and fear reactions in broilers.

Orthogonal functions based estimation of fNIRS signal strength as GLM parameters, in the course of real-time brain activation detection

Muhammad Aqil,Keum-Shik Hong,Myung-Yung Jeong 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

This paper presents a method to estimate the signal strength of the functional near infrared spectroscopy (fNIRS) as parameters of orthogonalized form of general linear model (GLM). The idea is to convert the basis function (design matrix) or explanatory variables of a GLM into orthogonal functions using the usual Gram-Schmidt orthogonalization procedure. The coefficients associated with the orthogonal functions are then easily estimated by applying the orthogonality condition. The original GLM coefficients are computed from these estimates. With this formulation, the estimation can be done recursively, making the approach applicable for real-time estimation. The results verify the effectiveness of the proposed technique by providing the activity levels at the measuring channels simultaneously while performing the motor-task experiment. It is worth mentioning that the technique is also providing the tracking of the motor tasks along with the activity of the channels during the experiment. The proposed method can be utilized for fNIRS based real-time brain imaging technology to cope the delay, inserted by the currently available off-line methods, in obtaining the medical diagnostics. It can further be utilized in applications demanding the real-time biofeedbacks.

Birmingham Mid-Head Resection Periprosthetic Fracture

Adeel Aqil,Hassaan Q. Sheikh,Milad Masjedi,Jonathan Jeffers,Justin Cobb 대한정형외과학회 2015 Clinics in Orthopedic Surgery Vol.7 No.3

Total hip arthroplasty in the young leads to difficult choices in implant selection. Until recently bone conserving options were not available for younger patients with deficient femoral head bone stock. The novel Birmingham Mid-Head Resection (BMHR) device offers the option of bone conserving arthroplasty in spite of deficient femoral head bone stock. Femoral neck fracture is a known complication of standard resurfacing arthroplasty and is the most common reason for revision. It is unknown whether this remains to be the case for the BMHR neck preserving implants. We report a case of a 57-year-old male, who sustained a periprosthetic fracture following surgery with a BMHR arthroplasty. This paper illustrates the first reported case of a BMHR periprosthetic fracture. The fracture pattern is spiral in nature and reaches to the subtrochanteric area. This fracture pattern is different from published cadaveric studies, and clinicians using this implant should be aware of this as revision is likely to require a distally fitting, rather than a metaphyseal fitting stem. We have illustrated the surgical technique to manage this rare complication.

Real-Time Brain Activation Detection by FPGA Implemented Kalman Filter

Muhammad Shahid Nazir,Muhammad Aqil,Ambreen Mustafa,Ameer Hamza Khan,Fatima Shams 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper presents an embedded system for real-time multi-channel brain activity detection by implementing the Kalman filter (KF) core on a field-programmable gate array (FPGA). The KF with a model driven approach is implemented on an FPGA, for the first time as per our knowledge. The model driven based brain activation model and its parameters" estimation methodology by KF is depicted from Aqil et al., 2012 (Detection of event-related hemodynamic response to neuroactivation by dynamic modeling of brain activity). The multiple instantiations of the KF core along with the coding of necessary compatibilities amongst the KF cores and with a single communication core, allow the parallel processing of multiple measurement channels. Through a serial universal asynchronous receiver/transmitter core, the fNIRS data is communicated to the system where it is being concurrently processed in 32-bit single precision IEEE754 format. The proposed fNIRS-KF embedded system is verified by an fNIRS dataset in real-time.

Deep Foundation Testing using Immunity-based Displacement Measurement in Successive-Sparse Images

Ali Raza,Umair Aqil,Ummul Baneen,Muhammad Q. Saleem 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.10

This paper presents a new immunity-based approach to measure the displacement of nodes (or points of interest) in successive-yet-sparse images, in order to measure the settlement of deep-foundations under heavy loads. It is developed as a close-range photogrammetric technique to search the nodes, similar to immune-cells searching bacteria in their vicinity. The immunological concepts of chemotaxis, biased random walk, diffusion and inflammation are implemented herein to accomplish the task. The technique greatly reduces the errors and is also validated on site of a mega project to record the settlements in deep foundations. The accuracy levels are found to be conforming to ASTM's standards for static load testing, including both compression and lateral-load tests. Unlike other techniques, such as particle image velocimetry, this approach is able to handle successive-images with varying ΔTbetween them. Furthermore, the technique is completely autonomous and does not require any embedded instrumentation.

Microstructural, mechanical, and electrochemical analysis of carbon doped AISI carbon steels

Ishtiaq Muhammad,Inam Aqil,Tiwari Saurabh,설재복 한국현미경학회 2022 Applied microscopy Vol.52 No.1

The effect of carbon doping contents on the microstructure, hardness, and corrosion properties of heat-treated AISI steel grades of plain carbon steel was investigated in this study. Various microstructures including coarse ferrite-pearlite, fine ferrite-pearlite, martensite, and bainite were developed by different heat treatments i.e. annealing, normalizing, quenching, and austempering, respectively. The developed microstructures, micro-hardness, and corrosion properties were investigated by a light optical microscope, scanning electron microscope, electromechanical (Vickers Hardness tester), and electrochemical (Gamry Potentiostat) equipment, respectively. The highest corrosion rates were observed in bainitic microstructures (2.68–12.12 mpy), whereas the lowest were found in the fine ferritic-pearlitic microstructures (1.57–6.36 mpy). A direct correlation has been observed between carbon concentration and corrosion rate, i.e. carbon content resulted in an increase in corrosion rate (2.37 mpy for AISI 1020 to 9.67 mpy for AISI 1050 in annealed condition).

The 2nd Metacarpal Cortical Index as a Simple Screening Tool for Osteopenia

Bhavika Patel,Adeel Aqil,Osman Riaz,Russ Jeffers,David Dickson 대한골대사학회 2020 대한골대사학회지 Vol.27 No.4

Background: Osteopenia is a known risk factor for sustaining skeletal fractures. Prevention of fragility fractures has obvious clinical and economic advantages, however screening all patients using a dual energy X-ray absorptiometry (DXA) is controversial not only because of the cost implications but also because it would potentially involve exposing a percentage of normal patients to unnecessary radiation. We wished to assess whether a simple hand X-ray measuring the 2nd metacarpal cortical index (2MCI) could be used as a simple screening tool for identifying patients with osteopenia. Methods: We retrospectively collected the radiographic data of 206 patients who had a simple radiograph of the hand and a DXA scan within one year of each other from our picture archiving and communication system database. The 2MCI was calculated for all patients. As data was parametric, a Pearson’s correlation was performed to assess association between T scores and 2MCI. Further analysis involved the construction of receiver operating characteristic (ROC) curves to identify a 2MCI index, which would give the most appropriate sensitivity and specificity values for identifying the presence of osteopenia. Results: A statistically significant and moderate correlation between DXA T-scores and 2MCI values was found (r=0.54, n=206, P<0.001). Further ROC curve analysis of normal and osteopenic subjects identified that a 2MCI of 41.5 had a sensitivity of 100% and specificity of 53% for detecting osteopenia. Conclusions: Our results support the use of the 2MCI as a simple screening tool for identifying patients with osteopenia.