470 research outputs found
Processing and Characterization of Samarium and Manganese Modified Lead Titanate Thin Film
Samarium and manganese modified lead titanate thin films were fabricated by spin-coating an amorphous citrate precursor. These films transformed into an oxide film upon heat treatment at 400 degrees Celcius or above. Relatively large area and crack-free thin films could be obtained by this process both easily and inexpensively. The rheological behavior of the precursor solution, as well as its thermal decomposition and phase development were studied by means of DSC/TGA and XRD. The thickness and grain size of the oxide film were examined by TEM and SEM
Cross-Power Spectrum and Its Application on Window Functions in the WMAP data
Cross-power spectrum is a quadratic estimator between two maps that can
provide unbiased estimate of the underlying power spectrum of the correlated
signals, which is therefore used for extracting the power spectrum in the WMAP
data. In this paper we discuss the limit of cross-power spectrum and derive the
residual from uncorrelated signal, which is the source of error in power
spectrum extraction. We employ the estimator to extract window functions by
crossing pairs of extragalactic point sources. We desmonstrate its usefulness
in WMAP Difference Assembly maps where the window functions are measured via
Jupiter and then extract the window functions of the 5 WMAP frequency band
maps.Comment: added the part of applying cross power spectrum on WMAP DA maps and
frequency band maps and submitted to Ap
Use of Equivalent Relative Utility (ERU) to Evaluate Artificial Intelligence-Enabled Rule-Out Devices
We investigated the use of equivalent relative utility (ERU) to evaluate the
effectiveness of artificial intelligence (AI)-enabled rule-out devices that use
AI to identify and autonomously remove non-cancer patient images from
radiologist review in screening mammography.We reviewed two performance metrics
that can be used to compare the diagnostic performance between the
radiologist-with-rule-out-device and radiologist-without-device workflows:
positive/negative predictive values (PPV/NPV) and equivalent relative utility
(ERU). To demonstrate the use of the two evaluation metrics, we applied both
methods to a recent US-based study that reported an improved performance of the
radiologist-with-device workflow compared to the one without the device by
retrospectively applying their AI algorithm to a large mammography dataset. We
further applied the ERU method to a European study utilizing their reported
recall rates and cancer detection rates at different thresholds of their AI
algorithm to compare the potential utility among different thresholds. For the
study using US data, neither the PPV/NPV nor the ERU method can conclude a
significant improvement in diagnostic performance for any of the algorithm
thresholds reported. For the study using European data, ERU values at lower AI
thresholds are found to be higher than that at a higher threshold because more
false-negative cases would be ruled-out at higher threshold, reducing the
overall diagnostic performance. Both PPV/NPV and ERU methods can be used to
compare the diagnostic performance between the radiologist-with-device workflow
and that without. One limitation of the ERU method is the need to measure the
baseline, standard-of-care relative utility (RU) value for mammography
screening in the US. Once the baseline value is known, the ERU method can be
applied to large US datasets without knowing the true prevalence of the
dataset
Effects of Lower Limb Cycling Training on Different Components of Force and Fatigue in Individuals With Parkinson’s Disease
The strength of lower extremity is important for individuals to maintain balance and ambulation functions. The previous studies showed that individuals with Parkinson’s disease suffered from fatigue and strength loss of central origin. The purpose of this study was to investigate the effect of lower extremities’ cycling training on different components of force and fatigue in individuals with Parkinson’s disease. Twenty-four individuals (13 males, 11 females, mean age: 60.58 ± 8.21 years) diagnosed with idiopathic Parkinson’s disease were randomized into training and control groups. The maximum voluntary contraction (MVC) force, voluntary activation level (VA), and twitch force of knee extensors were measured using a custom-made system with surface electrical stimulation. The general, central, and peripheral fatigue indexes (GFI, CFI, and PFI) were calculated after a fatiguing cycling protocol. Subjects received 8 weeks of low resistance cycling training (training group) or self-stretching (control group) programs. Results showed that MVC, VA, and twitch force improved (p \u3c 0.05) only in the training group. Compared to the baseline, central fatigue significantly improved in the training group, whereas peripheral fatigue showed no significant difference in two groups. The cycling training was beneficial for individuals with Parkinson’s disease not only in muscle strengthening but also in central fatigue alleviation. Further in-depth investigation is required to confirm the effect of training and its mechanism on central fatigue
Direct measurement of the angular power spectrum of cosmic microwave background temperature anisotropies in the WMAP Data
Angular power spectrum of the cosmic microwave background (CMB) temperature
anisotropies is one of the most important on characteristics of the Universe
such as its geometry and total density. Using flat sky approximation and
Fourier analysis, we estimate the angular power spectrum from an ensemble of
least foreground-contaminated square patches from WMAP W and V frequency band
map. This method circumvents the issue of foreground cleaning and that of
breaking orthogonality in spherical harmonic analysis due to masking out the
bright Galactic plane region, thereby rendering a direct measurement of the
angular power spectrum. We test and confirm Gaussian statistical characteristic
of the selected patches, from which the first and second acoustic peak of the
power spectrum are reproduced, and the third peak is clearly visible albeit
with some noise residual at the tail.Comment: 13 pages, 5 figure
Microfluidic assisted synthesis of silver nanoparticle–chitosan composite microparticles for antibacterial applications
AbstractSilver nanoparticle (Ag NP)-loaded chitosan composites have numerous biomedical applications; however, fabricating uniform composite microparticles remains challenging. This paper presents a novel microfluidic approach for single-step and in situ synthesis of Ag NP-loaded chitosan microparticles. This proposed approach enables obtaining uniform and monodisperse Ag NP-loaded chitosan microparticles measuring several hundred micrometers. In addition, the diameter of the composites can be tuned by adjusting the flow on the microfluidic chip. The composite particles containing Ag NPs were characterized using UV–vis spectra and scanning electron microscopy-energy dispersive X-ray spectrometry data. The characteristic peaks of Ag NPs in the UV–vis spectra and the element mapping or pattern revealed the formation of nanosized silver particles. The results of antibacterial tests indicated that both chitosan and composite particles showed antibacterial ability, and Ag NPs could enhance the inhibition rate and exhibited dose-dependent antibacterial ability. Because of the properties of Ag NPs and chitosan, the synthesized composite microparticles can be used in several future potential applications, such as bactericidal agents for water disinfection, antipathogens, and surface plasma resonance enhancers
Genetic algorithm integrated with artificial chromosomes for multi-objective flowshop scheduling problems
a b s t r a c t Recently, a wealthy of research works has been dedicated to the design of effective and efficient genetic algorithms in dealing with multi-objective scheduling problems. In this paper, an artificial chromosome generating mechanism is designed to reserve patterns of genes in elite chromosomes and to find possible better solutions. The artificial chromosome generating mechanism is embedded in simple genetic algorithm (SGA) and the non-dominated sorting genetic algorithm (NSGA-II) to solve single-objective and multiobjective flowshop-scheduling problems, respectively. The single-objective problems are to minimize the makespan while the multi-objective scheduling problems are to minimize the makespan and the maximum tardiness. Extensive numerical studies are conducted and the results indicate that artificial chromosomes embedded with SGA and NSGAII are able to further speed up the convergence of the genetic algorithm and improve the solution quality. This promising result may be of interests to industrial practitioners and academic researchers in the field of evolutionary algorithm or machine scheduling
Computational fluid dynamics modeling of symptomatic intracranial atherosclerosis may predict risk of stroke recurrence.
BackgroundPatients with symptomatic intracranial atherosclerosis (ICAS) of ≥ 70% luminal stenosis are at high risk of stroke recurrence. We aimed to evaluate the relationships between hemodynamics of ICAS revealed by computational fluid dynamics (CFD) models and risk of stroke recurrence in this patient subset.MethodsPatients with a symptomatic ICAS lesion of 70-99% luminal stenosis were screened and enrolled in this study. CFD models were reconstructed based on baseline computed tomographic angiography (CTA) source images, to reveal hemodynamics of the qualifying symptomatic ICAS lesions. Change of pressures across a lesion was represented by the ratio of post- and pre-stenotic pressures. Change of shear strain rates (SSR) across a lesion was represented by the ratio of SSRs at the stenotic throat and proximal normal vessel segment, similar for the change of flow velocities. Patients were followed up for 1 year.ResultsOverall, 32 patients (median age 65; 59.4% males) were recruited. The median pressure, SSR and velocity ratios for the ICAS lesions were 0.40 (-2.46-0.79), 4.5 (2.2-20.6), and 7.4 (5.2-12.5), respectively. SSR ratio (hazard ratio [HR] 1.027; 95% confidence interval [CI], 1.004-1.051; P = 0.023) and velocity ratio (HR 1.029; 95% CI, 1.002-1.056; P = 0.035) were significantly related to recurrent territorial ischemic stroke within 1 year by univariate Cox regression, respectively with the c-statistics of 0.776 (95% CI, 0.594-0.903; P = 0.014) and 0.776 (95% CI, 0.594-0.903; P = 0.002) in receiver operating characteristic analysis.ConclusionsHemodynamics of ICAS on CFD models reconstructed from routinely obtained CTA images may predict subsequent stroke recurrence in patients with a symptomatic ICAS lesion of 70-99% luminal stenosis
Multilayered Clouds Identification and Retrieval for CERES Using MODIS
Traditionally, analyses of satellite data have been limited to interpreting the radiances in terms of single layer clouds. Generally, this results in significant errors in the retrieved properties for multilayered cloud systems. Two techniques for detecting overlapped clouds and retrieving the cloud properties using satellite data are explored to help address the need for better quantification of cloud vertical structure. The first technique was developed using multispectral imager data with secondary imager products (infrared brightness temperature differences, BTD). The other method uses microwave (MWR) data. The use of BTD, the 11-12 micrometer brightness temperature difference, in conjunction with tau, the retrieved visible optical depth, was suggested by Kawamoto et al. (2001) and used by Pavlonis et al. (2004) as a means to detect multilayered clouds. Combining visible (VIS; 0.65 micrometer) and infrared (IR) retrievals of cloud properties with microwave (MW) retrievals of cloud water temperature Tw and liquid water path LWP retrieved from satellite microwave imagers appears to be a fruitful approach for detecting and retrieving overlapped clouds (Lin et al., 1998, Ho et al., 2003, Huang et al., 2005). The BTD method is limited to optically thin cirrus over low clouds, while the MWR method is limited to ocean areas only. With the availability of VIS and IR data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and MW data from the Advanced Microwave Scanning Radiometer EOS (AMSR-E), both on Aqua, it is now possible to examine both approaches simultaneously. This paper explores the use of the BTD method as applied to MODIS and AMSR-E data taken from the Aqua satellite over non-polar ocean surfaces
Compensating for the Threshold Voltages of Both the Driving Thin-Film Transistor and the Organic Light-Emitting Diode for Active-Matrix Organic Light-Emitting Diode Displays
This paper proposes a novel pixel circuit design and driving method for active-matrix organic light-emitting diode (AM-OLED) displays that use low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) as driving element. The automatic integrated circuit modeling simulation program with integrated circuit emphasis (AIM-SPICE) simulator was used to verify that the proposed pixel circuit, which comprises five transistors and one capacitor, can supply uniform output current. The voltage programming method of the proposed pixel circuit comprises three periods: reset, compensation with data input, and emission periods. The simulated results reflected excellent performance. For instance, when Δ TH = ±0.33 V, the average error rate of the OLED current variation was low (< 0.8%), and when Δ TH OLED = +0.33 V, the error rate of the OLED current variation was 4.7%. Moreover, when the × (current × resistance) drop voltage of a power line was 0.3 V, the error rate of the OLED current variation was 5.8%. The simulated results indicated that the proposed pixel circuit exhibits high immunity to the threshold voltage deviation of both the driving poly-Si TFTs and OLEDs, and simultaneously compensates for the × drop voltage of a power line
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