Computer-based stuttered speech detection system using Hidden Markov Model

Stuttering has attracted extensive research interests over the past decades. Most of the available stuttering diagnostics and assessment technique uses human perceptual judgment to overt stuttered speech characteristics. Conventionally, the stuttering severity is diagnosed by manual counting the number of occurrences of disfluencies of pre-recorded therapist-patient conversation. It is a time-consuming task, subjective, inconsistent and easily prone to error across clinics. Therefore, this thesis proposes a computerized system by deploying HMM-based speech recognition technique to detect the stuttered speech disfluency. The continuous Malay digit string has been used as the training and testing set for fluency detection. Hidden Markov Model (HMM) is a robust and powerful statistical-based acoustic modeling technique. With their efficient training algorithm (Forward-backward, Baum-Welch algorithms) and recognition algorithm, as well as its modeling flexibility in model topology and other knowledge sources, HMM has been successfully applied in solving various tasks. In this thesis, a set of normal voice for digit string as database is used for training HMM. Then, the pseudo stuttering voice was collected as testing set for proposed system. The generated experimental results were compared with the results made by Speech Language Pathologist (SLP) from Clinic of Audiology and Speech Sciences of Universiti Kebangsaan Malaysia (UKM). As a result, the proposed system is proven to be capable to achieve 100% average syllable repetition detection accuracy with 86.605% average sound prolongation detection accuracy. The SLP agreed with the result generated by the software. This system can be further enhanced for detecting stuttering disorder for daily speaking words where Microsoft Visual C++ 6.0 and Goldwave have been used for developing the software which can be executed under the window-based environment

Preventing shoulder-surfing attack with the concept of concealing the password objects' information

Traditionally, picture-based password systems employ password objects (pictures/icons/symbols) as input during an authentication session, thus making them vulnerable to “shoulder-surfing” attack because the visual interface by function is easily observed by others. Recent software-based approaches attempt to minimize this threat by requiring users to enter their passwords indirectly by performing certain mental tasks to derive the indirect password, thus concealing the user’s actual password. However, weaknesses in the positioning of distracter and password objects introduce usability and security issues. In this paper, a new method, which conceals information about the password objects as much as possible, is proposed. Besides concealing the password objects and the number of password objects, the proposed method allows both password and distracter objects to be used as the challenge set’s input. The correctly entered password appears to be random and can only be derived with the knowledge of the full set of password objects. Therefore, it would be difficult for a shoulder-surfing adversary to identify the user’s actual password. Simulation results indicate that the correct input object and its location are random for each challenge set, thus preventing frequency of occurrence analysis attack. User study results show that the proposed method is able to prevent shoulder-surfing attack

Nanoparticle sorting in silicon waveguide arrays

This paper presents the optical fractionation of nanoparticles in silicon waveguide arrays. The optical lattice is generated by evanescent coupling in silicon waveguide arrays. The hotspot size is tunable by changing the refractive index of surrounding liquids. In the experiment, 0.2-μm and 0.5-μm particles are separated with a recovery rate of 95.76%. This near-field approach is a promising candidate for manipulating nanoscale biomolecules and is anticipated to benefit the biomedical applications such as exosome purification, DNA optical mapping, cell-cell interaction, etc.NRF (Natl Research Foundation, S’pore)Published versio

Parallel alignment of bacteria using near-field optical force array for cell sorting

This paper presents a near-field approach to align multiple rod-shaped bacteria based on the interference pattern in silicon nano-waveguide arrays. The bacteria in the optical field will be first trapped by the gradient force and then rotated by the scattering force to the equilibrium position. In the experiment, the Shigella bacteria is rotated 90 deg and aligned to horizontal direction in 9.4 s. Meanwhile, ~150 Shigella is trapped on the surface in 5 min and 86% is aligned with angle < 5 deg. This method is a promising toolbox for the research of parallel single-cell biophysical characterization, cell-cell interaction, etc.NRF (Natl Research Foundation, S’pore)Published versio

An opto-mechanical coupled-ring reflector driven by optical force for lasing wavelength control

In this paper, an opto-mechanical coupled-ring reflector driven by optical gradient force is applied in an external-cavity tunable laser. A pair of mutually coupled ring resonators with a free-standing arc serves as a movable reflector. It obtains a 13.3-nm wavelength tuning range based on an opto-mechanical lasing-wavelength tuning coefficient of 127 GHz/nm. The potential applications include optical network, on-chip optical trapping, sensing, and biology detection.Published versio

Real-time measurement of single bacterium's refractive index using optofluidic immersion refractometry

This paper presents a biophysical method to characterize single bacterium in water by using an on-chip optofluidic immersion refractometer. Water safety is a major factor in the well-being of people, but the presence of bacteria such as Escherichia coli (E. coli), bacillus subtilis, Shigella flexneri and vibrio cholera in drinking water can lead to infectious diseases such as typhoid fever. Hence, it is crucial to detect and identify bacteria to prevent bacterial outbreaks. In this paper, an optofluidic immersion refractometer is developed to measure three biophysical parameters, i.e. size, shape and refractive index. The refractive index of a single bacterium is measured in high sensitivity of 0.005 RIU. This system is an innovative method to allow on-site real-time detection of single bacterium in water. It significantly reduces the amount of detection time and do not require trained personnel or additional chemical and biological reagents.Published versio

Optical potential-well array for high-selectivity, massive trapping and sorting at nanoscale

Optical tweezers are versatile tools capable of sorting microparticles, yet formidable challenges are present in the separation of nanoparticles smaller than 200 nm. The difficulties arise from the controversy on the requirement of a tightly focused light spot in order to create strong optical forces while a large area is kept for the sorting. To overcome this problem, we create a near-field potential well array with connected tiny hotspots in a large scale. This situation can sort nanoparticles with sizes from 100 to 500 nm, based on the differentiated energy depths of each potential well. In this way, nanoparticles of 200, 300, and 500 nm can be selectively trapped in this microchannel by appropriately tuning the laser power. Our approach provides a robust and unprecedented recipe for optical trapping and separation of nanoparticles and biomolecules, such that it presents a huge potential in the physical and biomedical sciences.Ministry of Education (MOE)National Research Foundation (NRF)Accepted versionThis work was supported by the Singapore National Research Foundation under the Competitive Research Program (NRFCRP13-2014-01), EWI Research & Innovation Scheme (1102- IRIS-05- 04), and the Singapore Ministry of Education (MOE) Tier 3 grant (MOE2017-T3-1-001). M.N.- V. acknowledges Spanish Ministerio de Ciencia, Innovación y Universidades, Grants No. FIS2014-55563-REDC, No. FIS2015-69295-C3-1-P, and No. PGC2018-095777-B-C21

Optofluidic Detection for Virus Infection Monitoring using Effective Refractive Index

International audienc

Fructose-1,6-bisphosphatase deficiency as a cause of recurrent hypoglycemia and metabolic acidosis: Clinical and molecular findings in Malaysian patients

Background: Fructose-1,6-bisphosphatase (FBPase) deficiency is a rare autosomal recessive inborn error of gluconeogenesis. We reported the clinical findings and molecular genetic data in seven Malaysian patients with FBPase deficiency. Methods: All patients diagnosed with FBPase deficiency from 2010 to 2015 were included in this study. Their clinical and laboratory data were collected retrospectively. Results: All the patients presented with recurrent episodes of hypoglycemia, metabolic acidosis, hyperlactacidemia and hepatomegaly. All of them had the first metabolic decompensation prior to 2 years old. The common triggering factors were vomiting and infection. Biallelic mutations in FBP1 gene (MIM*611570) were identified in all seven patients confirming the diagnosis of FBPase deficiency. In four patients, genetic study was prompted by detection of glycerol or glycerol-3-phosphate in urine organic acids analysis. One patient also had pseudo-hypertriglyceridemia. Seven different mutations were identified in FBP1, among them four mutations were new: three point deletions (c.392delT, c.603delG and c.704delC) and one splice site mutation (c.568-2A > C). All four new mutations were predicted to be damaging by in silico analysis. One patient presented in the neonatal period and succumbed due to sepsis and multi-organ failure. Among six survivors (current age ranged from 4 to 27 years), four have normal growth and cognitive development. One patient had short stature and another had neurological deficit following status epilepticus due to profound hypoglycemia. Conclusion: FBPase deficiency needs to be considered in any children with recurrent hypoglycemia and metabolic acidosis. Our study expands the spectrum of FBP1 gene mutations. Key Words: Fructose-1,6-bisphosphatase, FBPase deficiency, FBP1 gene mutatio

A silicon-nanowire memory driven by optical gradient force induced bistability

In this paper, a bistable optical-driven silicon-nanowire memory is demonstrated, which employs ring resonator to generate optical gradient force over a doubly clamped silicon-nanowire. Two stable deformation positions of a doubly clamped silicon-nanowire represent two memory states (“0” and “1”) and can be set/reset by modulating the light intensity (<3 mW) based on the optical force induced bistability. The time response of the optical-driven memory is less than 250 ns. It has applications in the fields of all optical communication, quantum computing, and optomechanical circuits.ASTAR (Agency for Sci., Tech. and Research, S’pore)MOE (Min. of Education, S’pore)Published versio