Showing papers by "Applied Science Private University published in 2012"

A monolithically integrated polarization entangled photon pair source on a silicon chip

Abstract: Integrated photonic circuits are one of the most promising platforms for large-scale photonic quantum information systems due to their small physical size and stable interferometers with near-perfect lateral-mode overlaps. Since many quantum information protocols are based on qubits defined by the polarization of photons, we must develop integrated building blocks to generate, manipulate, and measure the polarization-encoded quantum state on a chip. The generation unit is particularly important. Here we show the first integrated polarization-entangled photon pair source on a chip. We have implemented the source as a simple and stable silicon-on-insulator photonic circuit that generates an entangled state with 91 ± 2% fidelity. The source is equipped with versatile interfaces for silica-on-silicon or other types of waveguide platforms that accommodate the polarization manipulation and projection devices as well as pump light sources. Therefore, we are ready for the full-scale implementation of photonic quantum information systems on a chip.

Robust Nonlinear Predictive Controller for Permanent-Magnet Synchronous Motors With an Optimized Cost Function

Abstract: A robust nonlinear predictive controller for permanent-magnet synchronous motors is proposed. The nonlinear predictive control law is formulated by optimizing a novel cost function. A key feature of the proposed control is that it does not require the knowledge of the external perturbation and parameter uncertainties to enhance the robustness. A zero steady-state error is guaranteed by an integral action of the controller. The stability of the closed-loop system is ensured by convergence of the output-tracking error to the origin. The proposed control strategy is verified via simulation and experiment. High performance with respect to speed tracking and current control of the motor has been demonstrated.

An evaluation of the impact of antibiotic stewardship on reducing the use of high-risk antibiotics and its effect on the incidence of Clostridium difficile infection in hospital settings

Abstract: Results: The intervention was associated with a significant change in level of use of high-risk antibiotics (coefficient 217.3, P,0.0001) and with a borderline significant trend change in their use being reduced by 0.156 defined daily doses/100 bed-days per month (P ¼ 0.0597). The reduction in the use of high-risk antibiotics was associated with a significant change in the incidence trend of CDI (P ¼ 0.0081), i.e. the CDI incidence rate decreased by 0.0047/100 bed-days per month. Analysis showed that variations in the incidence of CDI were affected by the age-adjusted comorbidity index with a lag of 1 month (coefficient 0.137051, P ¼ 0.0182). Significant decreases in slope (coefficient 20.414, P ¼ 0.0309) post-intervention were also observed for the monitored medium-risk antibiotics. Conclusions: The restriction of the high-risk antibiotics contributed to both a reduction in their use and a reduction in the incidence of CDI in the study site hospital. Time-series analysis can be utilized as a risk classification tool with utility in antibiotic stewardship design and quality improvement programmes.

Robust Cascaded Nonlinear Predictive Control of a Permanent Magnet Synchronous Motor With Antiwindup Compensator

Abstract: A nonlinear predictive control (NPC) scheme in a cascaded structure for a permanent magnet synchronous motor drive is proposed. Taylor series expansion is used to predict the system response over a finite horizon. As NPC cannot remove completely the steady-state error in the presence of mismatched parameters and external perturbation, a disturbance observer is used to estimate the offset caused by parametric uncertainties and the load torque variation. In addition, input constraints (restrictions on the magnitude) are considered in the synthesis of the disturbance observer, resulting in an equivalent cascaded proportional integral action with an antiwindup compensator. The validity of the proposed controller was tested via simulation and experiment. Excellent results were obtained with respect to the speed trajectory tracking, stability, and disturbance rejection.

N-Doped graphene nanosheets for Li–air fuel cells under acidic conditions

Abstract: Nitrogen-doped graphene nanosheets (N-doped GNSs) show a high electrocatalytic activity for the air electrode of Li–air fuel cells based on hybrid electrolytes. N-Doped GNSs exhibit high discharge voltage under acidic conditions, which is near to that of commercial 20 wt% Pt/carbon black usually used in H2–O2 fuel cells.

The impact of antibiotic use on the incidence and resistance pattern of extended-spectrum beta-lactamase-producing bacteria in primary and secondary healthcare settings

Abstract: WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • The emergence and spread of bacteria producing extended-spectrum beta-lactamases (ESBLs) has important therapeutic and epidemiologic implications. • A key target for the establishment of hospital antibiotic stewardship is reducing the occurrence of additional antibiotic resistance. • Further research is needed to accumulate supporting evidence that reducing antibiotic use will result in a parallel reduction in antibiotic resistance. WHAT THIS STUDY ADDS • Fluoroquinolone restriction reversed ciprofloxacin resistance in primary and secondary healthcare settings. • Fluoroquinolone restriction reduced ESBL-producing bacteria incidence rates in both the primary and secondary healthcare settings. • This study highlights the value of time-series analysis in designing efficient antibiotic stewardship. AIMS The objective of the present study was to study the relationship between hospital antibiotic use, community antibiotic use and the incidence of extended-spectrum beta-lactamase (ESBL)-producing bacteria in hospitals, while assessing the impact of a fluoroquinolone restriction policy on ESBL-producing bacteria incidence rates. METHODS The study was retrospective and ecological in design. A multivariate autoregressive integrated moving average (ARIMA) model was built to relate antibiotic use to ESB-producing bacteria incidence rates and resistance patterns over a 5 year period (January 2005–December 2009). RESULTS Analysis showed that the hospital incidence of ESBLs had a positive relationship with the use of fluoroquinolones in the hospital (coefficient = 0.174, P= 0.02), amoxicillin-clavulanic acid in the community (coefficient = 1.03, P= 0.03) and mean co-morbidity scores for hospitalized patients (coefficient = 2.15, P= 0.03) with various time lags. The fluoroquinolone restriction policy was implemented successfully with the mean use of fluoroquinolones (mainly ciprofloxacin) being reduced from 133 to 17 defined daily doses (DDDs)/1000 bed days (P < 0.001) and from 0.65 to 0.54 DDDs/1000 inhabitants/day (P= 0.0007), in both the hospital and its surrounding community, respectively. This was associated with an improved ciprofloxacin susceptibility in both settings [ciprofloxacin susceptibility being improved from 16% to 28% in the community (P < 0.001)] and with a statistically significant reduction in ESBL-producing bacteria incidence rates. DISCUSSION This study supports the value of restricting the use of certain antimicrobial classes to control ESBL, and demonstrates the feasibility of reversing resistance patterns post successful antibiotic restriction. The study also highlights the potential value of the time-series analysis in designing efficient antibiotic stewardship.

Exploring Think-Alouds in Usability Testing: An International Survey

Abstract: Research problem: The study explored think-aloud methods usage within usability testing by examining the following questions: How, and why is the think-aloud method used? What is the gap between theory and practice? Where does this gap occur? Literature review: The review informed the survey design. Usability research based on field studies and empirical tests indicates that variations in think-aloud procedures may reduce test reliability. The guidance offered on think-aloud procedures within a number of handbooks on usability testing is also mixed. This indicates potential variability in practice, but how much and for what reasons is unknown. Methodology: An exploratory, qualitative survey was conducted using a web-based questionnaire (during November-December 2010). Usability evaluators were sought via emails (sent to personal contacts, usability companies, conference attendees, and special interest groups) to be cascaded to the international community. As a result we received 207 full responses. Descriptive statistics and thematic coding were used to analyze the data sets. Results: Respondents found the concurrent technique particularly suited usability testing as it was fast, easy for users to relate to, and requires limited resources. Divergent practice was reported in terms of think-aloud instructions, practice, interventions, and the use of demonstrations. A range of interventions was used to better understand participant actions and verbalizations, however, respondents were aware of potential threats to test reliability, and took steps to reduce this impact. Implications: The reliability considerations underpinning the classic think-aloud approach are pragmatically balanced against the need to capture useful data in the time available. A limitation of the study is the focus on the concurrent method; other methods were explored but the differences in application were not considered. Future work is needed to explore the impact of divergent use of think-aloud instructions, practice tasks, and the use of demonstrations on test reliability.

Antiproliferative, antimicrobial and apoptosis inducing effects of compounds isolated from Inula viscosa

Abstract: The antiproliferative and antimicrobial effects of thirteen compounds isolated from Inula viscosa (L.) were tested in this study. The antiproliferative activity was tested against three cell lines using the MTT assay. The microdilution method was used to study the antimicrobial activity against two Gram positive bacteria, two Gram negative bacteria and one fungus. The apoptotic activity was determined using a TUNEL colorimetric assay. Scanning electron microscopy was used to study the morphological changes in treated cancer cells and bacteria. Antiproliferative activity was observed in four flavonoids (nepetin, 3,3'-di-O-methylquercetin, hispidulin, and 3-O-methylquercetin). 3,3'-di-O-Methylquercetin and 3-O-methylquercetin showed selective antiproliferative activity against MCF-7 cells, with IC(50) values of 10.11 and 11.23 µg/mL, respectively. Both compounds exert their antiproliferative effect by inducing apoptosis as indicted by the presence of DNA fragmentation, nuclear condensation, and formation of apoptotic bodies in treated cancer cells. The antimicrobial effect of Inula viscosa were also noticed in 3,3'-di-O-methylquercetin and 3-O-methyquercetin that inhibited Bacillus cereus at MIC of 62.5 and 125 µg/mL, respectively. Salmonella typhimurium was inhibited by both compounds at MIC of 125 µg/mL. 3,3'-di-O-Methylquercetin induced damage in bacterial cell walls and cytoplasmic membranes. Methylated quercetins isolated from Inula viscosa have improved anticancer and antimicrobial properties compared with other flavonoids and are promising as potential anticancer and antimicrobial agents.

Enhanced activity of Ru/TiO2 catalyst using bisupport, bentonite-TiO2 for hydrogenolysis of glycerol in aqueous media

Abstract: A combination of bentonite-TiO2 was used as support to enhance the activity of Ru/TiO2 catalyst in hydrogenolysis of aqueous glycerol to 1,2-propanediol. A series of bentonite, TiO2, SiO2 and Al2O3 supported Ru catalyst were fabricated and characterized by XRD, XPS, BET, FESEM-EDX and TEM to establish some physicochemical properties of the catalysts. The activity of the catalysts was tested in glycerol hydrogenolysis reaction and were found to be in the following increasing order: Ru/SiO2 < Ru/TiO2 ≈ Ru/Al2O3 < Ru/bentonite. In particular, Ru/bentonite catalyst recorded the highest conversion (62.8%) of glycerol (20 wt%) with 80.1% selectivity to 1,2-pronediol at 150 ◦C, 20–30 bar H2 with a reaction duration of 7 h. The Ru/TiO2 catalyst exhibited the highest selectivity (83.7%) for hydrogenolysis of glycerol to 1,2-propanediol and with 38.8% conversion only. The activity of Ru/TiO2 catalyst was enhanced by adding bentonite to the titania support at 1:2 ratio resulting in an 80% increasing the activity from 38.8% to 69.8% under the same optimum condition for Ru/TiO2 while maintaining an 80% selectivity to 1,2-propanediol. TPD-NH3 analysis found that mixed support could increase catalyst acidity. CO pulse chemisorption analysis revealed that Ru particles was well dispersed with the smallest average size particles (1.5 nm) which could contribute to high activity of Ru/TiO2 catalyst for hydrogenolysis of glycerol

A Smart Nanofiber Web That Captures and Releases Cells

Abstract: Caught in a web: Photo-cross-linkable temperature-responsive polymer-based nanofiber webs have been synthesized that have the ability to capture, encapsulate, and release cells by dynamically transforming the fibrous structure into hydrogel-like structures by wrapping, swelling, and deswelling processes in response to external temperature changes (see picture).

Thermal relaxation of residual stress in laser shock peened Ti–6Al–4V alloy

Abstract: Laser shock peening (LSP) induced residual stresses in Ti–6Al–4V, and their thermal relaxation due to short-term exposure at elevated temperatures are investigated by an integrated modeling/simulation and experimental approach. A rate and temperature-dependent plasticity model in the form of Johnson–Cook (JC) has been employed to represent the nonlinear constitutive behavior under both LSP and thermal loads. By comparing the simulation results with experimental data, model parameters for Ti–6Al–4V are first calibrated and subsequently applied in analyzing the thermal stability of the residual stress in LSP-treated Ti–6Al–4V. The analysis shows that the magnitude of stress relaxation increases with the increase of applied temperature due to material softening. Most of stress relaxation occurs before 10 min to 20 min exposure in this study, and stress distribution becomes more uniform after thermal exposure. An analytical model based on the Zener–Wert–Avrami formula is then developed based on the simulation results. The activation enthalpy of the relaxation process for laser shock peened Ti–6Al–4V is determined to be in the range of 0.71 eV to 1.37 eV.

Immersed smoothed finite element method for fluid---structure interaction simulation of aortic valves

Abstract: This paper presents a novel numerical method for simulating the fluid---structure interaction (FSI) problems when blood flows over aortic valves. The method uses the immersed boundary/element method and the smoothed finite element method and hence it is termed as IS-FEM. The IS-FEM is a partitioned approach and does not need a body-fitted mesh for FSI simulations. It consists of three main modules: the fluid solver, the solid solver and the FSI force solver. In this work, the blood is modeled as incompressible viscous flow and solved using the characteristic-based-split scheme with FEM for spacial discretization. The leaflets of the aortic valve are modeled as Mooney-Rivlin hyperelastic materials and solved using smoothed finite element method (or S-FEM). The FSI force is calculated on the Lagrangian fictitious fluid mesh that is identical to the moving solid mesh. The octree search and neighbor-to-neighbor schemes are used to detect efficiently the FSI pairs of fluid and solid cells. As an example, a 3D idealized model of aortic valve is modeled, and the opening process of the valve is simulated using the proposed IS-FEM. Numerical results indicate that the IS-FEM can serve as an efficient tool in the study of aortic valve dynamics to reveal the details of stresses in the aortic valves, the flow velocities in the blood, and the shear forces on the interfaces. This tool can also be applied to animal models studying disease processes and may ultimately translate to a new adaptive methods working with magnetic resonance images, leading to improvements on diagnostic and prognostic paradigms, as well as surgical planning, in the care of patients.

Association between Physical Functionality and Falls Risk in Community-Living Older Adults

Abstract: Ageing-related declines in physiological attributes, such as muscle strength, can bring with them an increased risk of falls and subsequently greater risk of losing independence. These declines have substantial impact on an individual's functional ability. However, the precise relationship between falls risk and physical functionality has not been evaluated. The aims of this study were to determine the association between falls risk and physical functionality using objective measures and to create an appropriate model to explain variance in falls risk. Thirty-two independently living adults aged 65–92 years completed the FallScreen, the Continuous-Scale Physical Functional Performance 10 (CS-PFP10) tests, and the 12-Item Short-Form Health Survey (SF-12). The relationships between falls risk, physical functionality, and age were investigated using correlational and multiple hierarchical regression analyses. Overall, total physical functionality accounted for 24% of variance in an individual's falls risk while age explained a further 13%. The oldest-old age group had significantly greater falls risk and significantly lower physical functional performance. Mean scores for all measures showed that there were substantial (but not significant) differences between males and females. While increasing age is the strongest single predictor of increasing falls risk, poorer physical functionality was strongly, independently related to greater falls risk.

An Improved CO2–Oil Minimum Miscibility Pressure Correlation for Live and Dead Crude Oils

Abstract: An improved CO2–oil minimum miscibility pressure (MMP) correlation has been successfully developed to more accurately determine the CO2–oil MMP for a wide range of live and dead crude oils. Experimentally, slim-tube tests have been conducted to determine the CO2–oil MMPs for four crude oil samples with high molecular weights of C7+ fraction. Theoretically, the newly developed CO2–oil MMP correlation is originated from a CO2–oil MMP database from the literature that covers 51 CO2–oil MMP data for various live and dead oil samples, especially those with high C7+ molecular weights. The new CO2–oil MMP correlation is expressed as a function of reservoir temperature, C7+ molecular weight, and mole fraction ratio of volatile components (N2 and CH4) to intermediate components (CO2, H2S, and C2–C6). Compared to nine commonly used CO2–oil MMP correlations in the literature, it is found that the new CO2–oil MMP correlation provides the best reproduction of the literature CO2–oil MMP data with a percentage average a...

The effect of route of administration in thymoquinone toxicity in male and female rats.

Abstract: The maximum tolerated dose for intraperitoneal injection and oral ingestion of thymoquinone was determined in male and female Wistar rats. A range of dose levels of thymoquinone: 20, 30 and 40 mg/kg body weight for intraperitoneal injection and 200, 300 and 500 mg/kg body weight for oral ingestion were tested for acute toxicity in rats. The results showed that the maximum tolerated dose for intraperitoneal injection was 22.5 mg/kg in male rats and 15 mg/kg in females, whereas for oral ingestion it was 250 mg/kg in both male and female rats. There were different signs of toxicity shown in rats which received intraperitoneal injection from those that received oral ingestion of thymoquinone. Rats which received intraperitoneal injection of thymoquinone showed toxicity signs which were related to acute pancreatitis. Meanwhile, rats which received oral ingestion of thymoquinone showed transient toxicity signs. Two deaths were reported at dose of 500 mg/kg as a result of bowel obstruction complications. The data presented in this study indicate that the route of administration of thymoquinone could have an influence on thymoquinone toxicity outcome in both genders.

Error-Correction Coded Orbital-Angular-Momentum Modulation for FSO Channels Affected by Turbulence

Abstract: The performance of LDPC-precoded, orbital-angular-momentum (OAM) modulation is studied over a 1-km free-space laser communication link subject to OAM modal crosstalk induced by atmospheric turbulence. The multidimensional signal constellation is designed as the Cartesian product of a one-dimensional non-negative pulse-amplitude modulation and a set of orthogonal OAM modes. We evaluate the performance of this modulation scheme by first determining conditional probability density functions (PDFs) of the modal crosstalk for each symbol, resulting from the propagation in weak turbulence using a numerical propagation model. It is observed that OAM modulation is more sensitive to atmospheric turbulence as the number of dimensions increases. However, this can be efficiently mitigated by an error-correction code. The coded OAM modulation scheme provides an energy-efficient alternative to single-mode transmission, since a larger rate can be obtained per given bandwidth.

Experimental and Theoretical Determination of Equilibrium Interfacial Tension for the Solvent(s)–CO2–Heavy Oil Systems

Abstract: Equilibrium interfacial tension (IFT) between heavy oil and CO2 with the addition of C3H8 and/or n-C4H10 has been experimentally and theoretically determined. Experimentally, an axisymmetric drop shape analysis (ADSA) technique is used to measure both the dynamic and equilibrium IFTs between heavy oil and three pure solvents (i.e., CO2, C3H8, and n-C4H10) together with seven solvent mixtures. Theoretically, the Peng–Robinson equation of state (PR EOS) with a newly developed α function has been incorporated into a mechanistic parachor model to determine the equilibrium IFTs between heavy oil and pure solvents together with their corresponding mixtures. The addition of C3H8 and/or n-C4H10 into CO2 stream leads to an obvious reduction of IFT between heavy oil and CO2, although the degree of reduction depends upon the added amount of rich solvent(s). The mechanistic parachor model with the optimized parachor of the heavy oil and mass-transfer exponent provides a qualitative agreement with the measured equilib...

Durability of mortar and concretes containing slag with low hydraulic activity

Abstract: Granulated blast furnace slag has been widely used as a partial substitute for Portland cement in many applications because of advantages which include cost reduction, reduction in heat evolution and improvement of durability properties. However, the effectiveness of slag depends on its hydraulic reactivity. In this paper, the results of an experimental study on the effect of slag with low hydraulicity on the mechanical and durability properties of concrete and the performance of mortar under sulfate attack are discussed. Special attention is given to gas permeability and water absorption of slag concrete. The durability of slag concrete is improved at long term at low Water/Binder ratio. Sulfate resistance of mortar is improved by slag replacement up to 30%.

Slow Steaming in Container Shipping

Abstract: International supply chains heavily rely on maritime shipping. Since the beginning of the latest economical crisis, the containership fleet is slowing down. This paper gives a short overview of the slow steaming history as well as the widely assumed coherence between a ship's speed and its fuel consumption. Calculating fuel consumption as a function of speed provides decision support regarding the decision to which extent slowing down should be performed. It can be assumed that, compared to sailing at full speed, a speed reduction has a positive economic and also environmental impact. This paper is focused on the economic aspects. We show the considerable cost saving potential of a lower ship speed as a result of the decreasing fuel consumption. In combination with other variables of a container vessels' profit function, this may lead to the profit optimizing speed of a container carrier.

A Treeboost Model for Software Effort Estimation Based on Use Case Points

Abstract: Software effort prediction is an important task in the software development life cycle. Many models including regression models, machine learning models, algorithmic models, expert judgment and estimation by analogy have been widely used to estimate software effort and cost. In this work, a Tree boost (Stochastic Gradient Boosting) model is put forward to predict software effort based on the Use Case Point method. The inputs of the model include software size in use case points, productivity and complexity. A multiple linear regression model was created and the Tree boost model was evaluated against the multiple linear regression model, as well as the use case point model by using four performance criteria: MMRE, PRED, MdMRE and MSE. Experiments show that the Tree boost model can be used with promising results to estimate software effort.

Melt Homogenization and Self-Organization in Chalcogenides-Part II

Abstract: An FT-Raman profiling method is developed to monitor growth of structural homogeneity of binary GexSe100-x melts in real time (tR) non-invasively as starting materials are reacted over days Raman spectra of quenched melts were acquired along a one inch long column of a sample in a quartz tube In the first step of reaction, tR < 2 days, Ge-rich crystalline- and glassy- phases form and coexist with Se-rich glasses In the second step, tR extending up to 7 days, local structures characteristic of melts/glasses form, and steadily homogenize as Ge and Se atoms diffuse The process terminates when all Raman lineshapes taken along the length of a sample coalesce into unique profile Several factors contribute to the long reaction time tR for melts to homogenize, including liquid density difference of Ge and Se, diffusion controlled nanoscale mixing of melts, batch dryness, batch sizes, and laser spot size Physical properties of such homogeneous GexSe100-x glasses are found to be quite different from their inhomogeneous counterparts realized after the first step of reaction Slow homogenization of chalcogenides melts may occur generally Variations in physical properties of chalcogenide glasses possessing nominally the same composition may have their origin in structural heterogeneity and purity