A very convenient setup to generate intense VUV coherent light at 125 nm with use of nonlinear effects in mercury vapor at room temperature

Using only one dye laser, efficient generation of VUV radiation (10^13 photons/pulse) is demonstrated at 125.140 nm and 125.053 nm by four-wave sum-frequency mixing in a room-temperature mercury vapor. The emission at 125.053 nm, which is out of two-photon resonance but near three-photon resonance, has been observed for the first time and is carefully analyzed. In particular, numerical calculations have been carried out for gaussian pump beams taking into account absorption of VUV photons and optical Kerr effect. The results of the calculations reproduce the VUV emission lineshape and power saturation effects measured in the experiment

Scaling of anisotropy flows in intermediate energy heavy ion collisions

Anisotropic flows ($v_1$, $v_2$ and $v_4$) of light nuclear clusters are studied by a nucleonic transport model in intermediate energy heavy ion collisions. The number-of-nucleon scalings of the directed flow ($v_1$) and elliptic flow ($v_2$) are demonstrated for light nuclear clusters. Moreover, the ratios of $v_4/v_2^2$ of nuclear clusters show a constant value of 1/2 regardless of the transverse momentum. The above phenomena can be understood by the coalescence mechanism in nucleonic level and are worthy to be explored in experiments.Comment: Invited talk at "IX International Conference on Nucleus-Nucleus Collisions", Rio de Janeiro, Aug 28- Sept 1, 2006; to appear on the proceeding issue in Nuclear Physics

Scaling of Anisotropic Flow and Momentum-Space Densities for Light Particles in Intermediate Energy Heavy Ion Collisions

Anisotropic flows ($v_2$ and $v_4$) of light nuclear clusters are studied by Isospin-Dependent Quantum Molecular Dynamics model for the system of $^{86}$Kr + $^{124}$Sn at intermediate energy and large impact parameters. Number-of-nucleon scaling of the elliptic flow ($v_2$) are demonstrated for the light fragments up to $A$ = 4, and the ratio of $v_4/v_2^2$ shows a constant value of 1/2. In addition, the momentum-space densities of different clusters are also surveyed as functions of transverse momentum, in-plane transverse momentum and azimuth angle relative to the reaction plane. The results can be essentially described by momentum-space power law. All the above phenomena indicate that there exists a number-of-nucleon scaling for both anisotropic flow and momentum-space densities for light clusters, which can be understood by the coalescence mechanism in nucleonic degree of freedom for the cluster formation.Comment: 8 pages, 3 figures; to be published in Physics Letters

Azimuthal asymmetry of direct photons in intermediate energy heavy-ion collisions

Hard photon emitted from energetic heavy ion collisions is of very interesting since it does not experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we have presented a first calculation of azimuthal asymmetry, characterized by directed transverse flow parameter $F$ and elliptic asymmetry coefficient $v_2$, for proton-neutron bremsstrahlung hard photons in intermediate energy heavy-ion collisions. The positive $F$ and negative $v_2$ of direct photons are illustrated and they seem to be anti-correlated to the corresponding free proton's flow.Comment: 7 pages, 4 figures; accepted by Physics Letters

Improved Voice Activity Detection based on support vector machine with high separable speech feature vectors

Voice Activity Detection (VAD) is one of the key techniques for many speech applications. Existing VAD algorithms have shown unsatisfied performance under nonstationary noise and low Signal-to-Noise-Ratio (SNR) situations. Motivated by the fact that people is able to distinguish the speech and non-speech even in low SNR situations, this paper studies the VAD technique from the pattern recognition point of view, where the VAD essentially is formulated as a binary classification problem. Specifically, the VAD is implemented by classifying the speech signal into speech and non-speech segments. The radial basis function (RBF) based support vector machine (SVM) is employed with supervised manner, which is perfectly suitable for binary classification tasks with some training samples. Aiming at achieving improved accuracy and robustness of the VAD technique to noise, the feature selection has been conducted by introducing the class separation measure (CSM) criterion to evaluate the capability of the feature vectors extracted for classifying speech and non-speech segments. Most famous speech features have been taken into account, including Mel-frequency cepstral coefficients (MFCC), the principal component analysis of the MFCC (PCA-MFCC), linear predictive coding (LPC) and linear predictive cepstral coding (LPCC). Intensive experimental results show that the MFCC features capture the most relevant information of speech and keep good separability of classification in different noisy conditions, so do the PCA-MFCC features. Moreover, the PCA-MFCC features are more robust to the noise with less computational cost. As a result, a VAD method by using the PCA-MFCC and the RBF-SVM as the classifier has been developed, which is termed as PCA-SVM-VAD for short. The experimental results with the NOIZEUS database show that the proposed PCA-SVM-VAD method has clear improvements over other VAD methods and performs much more robust in car noisy environment at various SNRs. ? 2014 IEEE.EI763-7672014-Januar

Nanoscale precipitation in aged Al-3.5Cu-0.4Mg-0.2Ge alloy

During ageing at 200 °C, a trace (0.2 wt%) addition of Ge to a base Al–3.5Cu–0.4Mg alloy resulted in anomalous precipitation processes by stimulating the formation of nanoscale precipitate and suppressing the formation of S′(Al2CuMg) precipitate. This behavior was demonstrated to be closely related to the preferential Mg–Ge cluster which formed in the early ageing stage. The increased hardening response and enhanced hardness in Ge-containing alloy were due to the rapid precipitation of high density of fine nanoscale precipitate. The transmission electron microscopy (TEM) investigation indicated that nanoscale precipitate, θ′ (Al2Cu), θ′II (Al2Cu) and σ (Al5Cu6Mg2) precipitates could coexist in Al matrix for prolonged ageing at 200 °C. And the nanoscale precipitate was demonstrated to own 〈001〉α needle-shaped morphology and be enriched with aluminum, copper, magnesium and germanium. The Mg/(Cu+Ge) atomic ratio in them is close to 1:1. High-resolution TEM observation indicated that the nanoscale precipitates appeared to be coherent with Al matrix and their orientation relationship is 〈100〉nano//〈100〉Al and {010}nano//{010}Al. A modified structure with composition of Al10Mg3Cu3−xGex (

Prognostic value of bronchioloalveolar carcinoma component in lung adenocarcinoma

BAC is a common pattern in conventional lung adenocarcinoma. In the past, however, there were no well-defined criteria for BAC. As a result, it was difficult to evaluate the prognosis on this type of lung adenocarcinoma. Though the 1999 WHO classification of BAC provides a useful framework, it does not provide detailed enough information to predict prognosis in lung adenocarcinomas with BAC feature. The aim of this study was to address the prognostic value of bronchioloalveolar carcinoma (BAC) component in lung adenocarcinoma. Ninety-one consecutive surgically treated patients with adenocarcinoma exhibiting various degrees of BAC features and complete follow-up records were retrospectively studied. According to the percentage of BAC component designed as less than 50%, 50%-79%, 80%-99%, and 100% , tumors were classified as type I, type II, type III, and type IV respectively. The overall 5- year survival rate was 64.84%. Multivariate analysis revealed that the four classified types are independent prognostic factors (P=0.0008), as is tumor stage (P=0.0000). The 5-year survival rates were 39.29%, 58.82%, 81.25%, 85.71% for the four classified types respectively, and were 88.89% for stage I, 46.15% for stage II, and 23.81% for stage III. However, the size of tumor (>2 cm) was significant only in the univariate analysis (P=0.0275). In the patients with tumor size exceeding 2 cm in diameter, the BAC component was also significant to predict prognosis (p=0.0008). In lung adenocarcinoma, the BAC component may prove to be useful to predict the outcome of the patients, and the percentage of BAC pattern and pathological stage appear to be two independent prognostic factors

An index guiding temporal planting policies for wind erosion reduction

Vegetation cover has spatial as well as temporal characteristics, but the latter are often neglected. Temporal cover characteristics were explored to recommend planting policies for returning arable land into land better protected from serious wind erosion during late autumn, winter, and particularly early spring, when crop cover is non existent. An index combining a wind erosive factor and a soil cover factor permits relative quantification of expected erosion, allowing a forecasting of the wind erosion hazard. This index was quantified under the conditions of Wuchuan County, Inner Mongolia, but derived planting policies using the index can be extended to other regions. Because ground cover with much surface contact or undergrowth is needed to reduce wind erosion, it is recommended to grow perennial grasses with shrubs rather than planting forests/woodland, annual pasture, and crops that are totally removed during harvest. If such land stays under annual cropping, geometrically efficient winter stubble patterns assisted by shrub planting will have to be develope