Single crystalline beta-SiAlON nanowhiskers: preparation and enhanced properties at high temperature

Single crystalline β-SiAlON (z = 1.0) nanowhiskers with uniform morphology were prepared using a reaction sintering method at 1773 K for 6 h under flowing nitrogen atmosphere. The as-synthesized whiskers were well-crystallized with about 100-200 nm in diameter and a few hundred microns in length. According to the thermodynamic calculation, Al(g) and SiO(g) are important intermediate reactants to synthesize β-SiAlON whiskers. In the experiment, the two phases was controlled by changing the flow rate of nitrogen to make β-SiAlON whiskers grow in a stable way. The formation of β-SiAlON whiskers occurred through a vapor-solid (VS) mechanism. SiAlON was found to grow as a single crystal whisker from the (1010) plane of the granule. Furthermore, an enhanced oxidation resistance for β-SiAlON whiskers at high temperature was also observed using the thermogravimetry method (TG), demonstrating that β-SiAlON whiskers with uniform morphology is a promising candidate as a reinforcing agent in composite

Decay Constants of Pseudoscalar DD-mesons in Lattice QCD with Domain-Wall Fermion

We present the first study of the masses and decay constants of the pseudoscalar $D$ mesons in two flavors lattice QCD with domain-wall fermion. The gauge ensembles are generated on the $24^3 \times 48$ lattice with the extent $N_s = 16$ in the fifth dimension, and the plaquette gauge action at $\beta = 6.10$, for three sea-quark masses with corresponding pion masses in the range $260-475$ MeV. We compute the point-to-point quark propagators, and measure the time-correlation functions of the pseudoscalar and vector mesons. The inverse lattice spacing is determined by the Wilson flow, while the strange and the charm quark masses by the masses of the vector mesons $\phi(1020)$ and $J/\psi(3097)$ respectively. Using heavy meson chiral perturbation theory (HMChPT) to extrapolate to the physical pion mass, we obtain $f_D = 202.3(2.2)(2.6)$ MeV and $f_{D_s} = 258.7(1.1)(2.9)$ MeV.Comment: 15 pages, 3 figures. v2: the statistics of ensemble (A) with m_sea = 0.005 has been increased, more details on the systematic error, to appear in Phys. Lett.

Stationary Light Pulses in Cold Atomic Media

Stationary light pulses (SLPs), i.e., light pulses without motion, are formed via the retrieval of stored probe pulses with two counter-propagating coupling fields. We show that there exist non-negligible hybrid Raman excitations in media of cold atoms that prohibit the SLP formation. We experimentally demonstrate a method to suppress these Raman excitations and realize SLPs in laser-cooled atoms. Our work opens the way to SLP studies in cold as well as in stationary atoms and provides a new avenue to low-light-level nonlinear optics.Comment: 4 pages, 4 figure

Changes in corneal curvature after wearing the orthokeratology lens

AbstractIntroductionThe orthokeratology lens (OK lens) is designed to reshape the cornea and correct refraction error. Owing to the convenience of ceasing the use of glasses during the day, the use of the OK lens is increasing in myopic children. In this study, changes in corneal curvature and astigmatism after wearing the OK lens were analyzed.MethodsThis retrospective cohort study included 65 children (130 eyes) who underwent full and regular examinations. None of the participants had any ocular disease other than myopia and astigmatism. The OK lenses used in this study were four-zone, reverse-geometry lenses. The corneal curvature of each patient was checked annually after the patients discontinued daily wearing of the OK lens for 10 days. Student t test and repeated measures analysis of variance (ANOVA) analyses were performed to compare the results.ResultsThe radius of corneal curvature showed a progressive annual increase with significant differences, both in the steepest and flattest radius of the corneal curvature (p < 0.001 and p = 0.001, respectively). The mean radius of the steepest and flattest corneal curvature increased significantly from baseline to the following years consecutively (all p < 0.001). Nevertheless, astigmatism did not change significantly in any of the tests.ConclusionCorneal curvature changed as the patients grew older. There was a statistically significant increase in the radius of the corneal curvature in the myopic children studied. For correct fit of OK lenses, the radius of the corneal curvature should be regularly checked prior to dispensing a new set of lenses

High Altitude Pulmonary Edema in a Patient with Previous Pneumonectomy

High altitude pulmonary edema (HAPE) is a life-threatening illness that can occur in individuals ascending to altitudes exceeding 2400 m. The risk factors are rapid ascent, physical exertion and a previous history of HAPE. This work presents a case study of a 74-year-old man who underwent left side pneumonectomy 40 years ago and subsequently experienced several instances of HAPE. The well-known risk factors for HAPE were excluded in this patient. We suspect that the post-pneumonectomy condition may be a risk factor for HAPE based on this case. [J Formos Med Assoc 2007;106(4):320-322

Project dispute prediction by hybrid machine learning techniques

This study compares several well-known machine learning techniques for public-private partnership (PPP) project dispute problems. Single and hybrid classification techniques are applied to construct models for PPP project dispute prediction. The single classification techniques utilized are multilayer perceptron (MLP) neural networks, decision trees (DTs), support vector machines, the naïve Bayes classifier, and k-nearest neighbor. Two types of hybrid learning models are developed. One combines clustering and classification techniques and the other combines multiple classification techniques. Experimental results indicate that hybrid models outperform single models in prediction accuracy, Type I and II errors, and the receiver operating characteristic curve. Additionally, the hybrid model combining multiple classification techniques perform better than that combining clustering and classification techniques. Particularly, the MLP+MLP and DT+DT models perform best and second best, achieving prediction accuracies of 97.08% and 95.77%, respectively. This study demonstrates the efficiency and effectiveness of hybrid machine learning techniques for early prediction of dispute occurrence using conceptual project information as model input. The models provide a proactive warning and decision-support information needed to select the appropriate resolution strategy before a dispute occurs

Thrombolysis in Myocardial Infarction Frame Count in Single-Vessel Disease After Angioplasty

SUMMARYBackgroundWe compared the thrombolysis in myocardial infarction (TIMI) frame count and examined the impact of angioplasty on the count between patients with normal coronary angiograms and those with single-vessel disease (SVD).MethodsIn 780 consecutive patients referred for coronary angiography, TIMI frame count was measured for 149 patients who had SVD and 32 patients with normal angiograms who underwent the procedure for electro-physiologic study or valvular heart disease survey.ResultsComparison of each of the three vessels in the normal vessel group with the corresponding non-stenotic vessels in the SVD group showed similar counts in each of the left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA). For the stenotic vessels, after successful angioplasty, the counts were all reduced (LAD, 54.5 ±28.8 vs. 34.0 ±19.3; LCX, 67.3 ±31.1 vs. 34.1 ±19.0; RCA, 33.2 ±28.1 vs. 19.3 ±7.9; all p <0.05). In addition, the count in the RCA after angioplasty was lower, compared with the RCA of the normal group (19.3 ±7.9 vs. 29.1 ±14.6, p = 0.001). Multivariate analysis showed that the use of oral calcium channel blockers was the only independent predictor for the reduction in RCA after angioplasty.ConclusionIn patients with SVD, the data of TIMI frame count in the nonstenotic vessels were similar to those without the disease, suggesting that the count in the normal artery is not affected by the adjacent stenotic artery. For the stenotic vessels, angioplasty had differential effects on each of the three arteries, indicating the existence of distinct properties, which is affected by calcium channel blockers, for individual coronary arteries in response to atherosclerosis and/or angioplasty