Microfluidic system for high throughput characterisation of echogenic particles

Echogenic particles, such as microbubbles and volatile liquid micro/nano droplets, have shown considerable potential in a variety of clinical diagnostic and therapeutic applications. The accurate prediction of their response to ultrasound excitation is however extremely challenging, and this has hindered the optimisation of techniques such as quantitative ultrasound imaging and targeted drug delivery. Existing characterisation techniques, such as ultra-high speed microscopy provide important insights, but suffer from a number of limitations; most significantly difficulty in obtaining large data sets suitable for statistical analysis and the need to physically constrain the particles, thereby altering their dynamics. Here a microfluidic system is presented that overcomes these challenges to enable the measurement of single echogenic particle response to ultrasound excitation. A co-axial flow focusing device is used to direct a continuous stream of unconstrained particles through the combined focal region of an ultrasound transducer and a laser. Both the optical and acoustic scatter from individual particles are then simultaneously recorded. Calibration of the device and example results for different types of echogenic particle are presented, demonstrating a high throughput of up to 20 particles per second and the ability to resolve changes in particle radius down to 0.1 ?m with an uncertainty of less than 3%

Direct medical cost of type 2 diabetes in Singapore

10.1371/joumal.pone.0122795PLoS ONE103e012279

An Explanatory Case Study on Passenger Service Systems Adoption: A Taiwanese Air Carrier

This study explains the adoption of Passenger Service Systems (PSS) in airlines through the lens of Inter-organizational Systems adoption and home-region orientation. It examined 20 causal factors influencing PSS adoption and tested an original research model in the technology–organization–environment context, by applying transactional cost theory and neo-institutional theory. Prior to a cross-case study across multiple airlines, the explanatory single-case research analyzed interview data from four informants with a Taiwanese carrier and multiple industry reports; the key findings highlight: (i) interoperable functionality and industry standards as external technological drivers strongly influenced full conversion to the PSS platform; (ii) within the organizational context, commitment to global network, organizational transformation and top management support were identified as salient internal factors in decision-making and resource allocation, while normative pressures from an alliance body exerted a stronger influence over the airline than any other isomorphic forces; and (iii) in the context of environment, full conversion was also facilitated by PSS vendors and powered by the need for mutual worldwide learning to effectively operate foreign markets from home region. This in-depth case study provides insights that PSS in a common-use environment can bring business value to PSS user airlines in accessing a broader global market, offering greater competitive services and expanding distribution channels. To increase causality and generalizability, future work involving an embedded multi-case study with three East Asian carriers will be undertaken. Available at: https://aisel.aisnet.org/pajais/vol11/iss1/2

On Mobility Management in Multi-Sink Sensor Networks for Geocasting of Queries

In order to efficiently deal with location dependent messages in multi-sink wireless sensor networks (WSNs), it is key that the network informs sinks what geographical area is covered by which sink. The sinks are then able to efficiently route messages which are only valid in particular regions of the deployment. In our previous work (see the 5th and 6th cited documents), we proposed a combined coverage area reporting and geographical routing protocol for location dependent messages, for example, queries that are injected by sinks. In this paper, we study the case where we have static sinks and mobile sensor nodes in the network. To provide up-to-date coverage areas to sinks, we focus on handling node mobility in the network. We discuss what is a better method for updating the routing structure (i.e., routing trees and coverage areas) to handle mobility efficiently: periodic global updates initiated from sinks or local updates triggered by mobile sensors. Simulation results show that local updating perform very well in terms of query delivery ratio. Local updating has a better scalability to increasing network size. It is also more energy efficient than ourpreviously proposed approach, where global updating in networks have medium mobility rate and speed

Highly Efficient Q-switched Ho:YLF Laser Pumped by Tm:Fiber Laser

A highly efficient Q-switched Ho:YLF laser pumped by a Tm:fiber laser has been designed and demonstrated. When the pump power is 30 W, the pulse energy is 30mJ at the repetition rate of 100Hz

Efficient Operation of Conductively Cooled Ho:Tm:LuLiF Laser Oscillator/Amplifier

A conductively-cooled Ho:Tm:LuLiF laser oscillator generates 1.6J normal mode pulses at 10Hz with optical to optical efficiency of 20%. When the laser head module is used as the amplifier, the double-pass small-signal amplification excesses 25

Performance of the international physical activity questionnaire (short form) in subgroups of the Hong Kong chinese population

Background: The International Physical Activity Questionnaire (IPAQ-SF) has been validated and recommended as an efficient method to assess physical activity, but its validity has not been investigated in different population subgroups. We examined variations in IPAQ validity in the Hong Kong Chinese population by six factors: sex, age, job status, educational level, body mass index (BMI), and visceral fat level (VFL).Methods: A total of 1,270 adults (aged 42.9 ± SD 14.4 years, 46.1% male) completed the Chinese version of IPAQ (IPAQ-C) and wore an accelerometer (ActiGraph) for four days afterwards. The IPAQ-C and the ActiGraph were compared in terms of estimated Metabolic Equivalent Task minutes per week (MET-min/wk), minutes spent in activity of moderate or vigorous intensity (MVPA), and agreement in the classification of physical activity.Results: The overall Spearman correlation (ρ) of between the IPAQ-C and ActiGraph was low (0.11 ± 0.03; range in subgroups 0.06-0.24) and was the highest among high VFL participants (0.24 ± 0.05). Difference between self-reported and ActiGraph-derived MET-min/wk (overall 2966 ± 140) was the smallest among participants with tertiary education (1804 ± 208). When physical activity was categorized into over or under 150 min/wk, overall agreement between self-report and accelerometer was 81.3% (± 1.1%; subgroup range: 77.2%-91.4%); agreement was the highest among those who were employed full-time in physically demanding jobs (91.4% ± 2.7%).Conclusions: Sex, age, job status, educational level, and obesity were found to influence the criterion validity of IPAQ-C, yet none of the subgroups showed good validity (ρ = 0.06 to 0.24). IPAQ-SF validity is questionable in our Chinese population. © 2011 Lee et al; licensee BioMed Central Ltd.published_or_final_versio

High Repetition Rate Pulsed 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed at NASA Langley Research Center. Such a laser transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of approximately 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. The measured standard deviation of the laser frequency jitter is about 3 MHz

Dual focus polarisation splitting lens

We have successfully designed and measured a unique polarisation splitting lens which focuses the orthogonal linear polarisations side-by-side in the lens focal plane. This concept can find application in situations where there is limited space for the beam splitters and focusing optics that are required for incoherent detectors