Adaptation of maximum entropy capitalizer: Little data can help a lot

A novel technique for maximum “a posteriori” (MAP) adaptation of maximum entropy (MaxEnt) and maximum entropy Markov models (MEMM) is presented.The technique is applied to the problem of automatically capitalizing uniformly cased text. Automatic capitalization is a practically relevant problem: speech recognition output needs to be capitalized; also, modern word processors perform capitalization among other text proofing algorithms such as spelling correction and grammar checking. Capitalization can be also used as a preprocessing step in named entity extraction or machine translation.A “background” capitalizer trained on 20 M words of Wall Street Journal (WSJ) text from 1987 is adapted to two Broadcast News (BN) test sets – one containing ABC Primetime Live text and the other NPR Morning News/CNN Morning Edition text – from 1996.The “in-domain” performance of the WSJ capitalizer is 45% better relative to the 1-gram baseline, when evaluated on a test set drawn from WSJ 1994. When evaluating on the mismatched “out-of-domain” test data, the 1-gram baseline is outperformed by 60% relative; the improvement brought by the adaptation technique using a very small amount of matched BN data – 25–70k words – is about 20–25% relative. Overall, automatic capitalization error rate of 1.4% is achieved on BN data.The performance gain obtained by employing our adaptation technique using a tiny amount of out-of-domain training data on top of the background data is striking: as little as 0.14 M words of in-domain data brings more improvement than using 10 times more background training data (from 2 M words to 20 M words).     

Defect-free wet etching through pyrex glass using Cr/Au mask

This paper reports the highest etch depth of annealed Pyrex glass achieved by wet etching in highly concentrated HF solution, using a low stress chromium–gold with assistance of photoresist as masking layer. The strategies to achieve that are: increasing the etch rate of glass and simultaneously increasing the resistance of Cr/Au mask in the etchant. By annealing the Pyrex glass and using a highly concentrated HF acid, a high etch rate can be obtained. Furthermore, a method to achieve a good resistance of the Cr/Au masking layer in the etching solution is to control the residual stress and to increase the thickness of Au deposition up to 1 μm. In addition, the presence of a hard baked photoresist can improve the etching performance. As a result, a 500-μm thick Pyrex glass wafer was etched through.     

Finite Size Effects on the Switching Dynamics of Spin‐Crossover Thin Films Photoexcited by a Femtosecond Laser Pulse

Using ultrafast optical absorption spectroscopy, the room‐temperature spin‐state switching dynamics induced by a femtosecond laser pulse in high‐quality thin films of the molecular spin‐crossover (SCO) complex [Fe(HB(tz)₃)₂] (tz = 1,2,4‐triazol‐1‐yl) are studied. These measurements reveal that the early, sub‐picosecond, low‐spin to high‐spin photoswitching event, with linear response to the laser pulse energy, can be followed under certain conditions by a second switching process occurring on a timescale of tens of nanoseconds, enabling nonlinear amplification. This out‐of‐equilibrium dynamics is discussed in light of the characteristic timescales associated with the different switching mechanisms, i.e., the electronic and structural rearrangements of photoexcited molecules, the propagation of strain waves at the material scale, and the thermal activation above the molecular energy barrier. Importantly, the additional, nonlinear switching step appears to be completely suppressed in the thinnest (50 nm) film due to the efficient heat transfer to the substrate, allowing the system to retrieve the thermal equilibrium state on the 100 ns timescale. These results provide a first milestone toward the assessment of the physical parameters that drive the photoresponse of SCO thin films, opening up appealing perspectives for their use as high‐frequency all‐optical switches working at room temperature.     

Characterisation of silicon carbide films deposited by plasma-enhanced chemical vapour deposition

The paper presents a characterisation of amorphous silicon carbide films deposited in plasma-enhanced chemical vapour deposition (PECVD) reactors for MEMS applications. The main parameter was optimised in order to achieve a low stress and high deposition rate. We noticed that the high frequency mode (13.56 MHz) gives a low stress value which can be tuned from tensile to compressive by selecting the correct power. The low frequency mode (380 kHz) generates high compressive stress (around 500 MPa) due to ion bombardment and, as a result, densification of the layer achieved. Temperature can decrease the compressive value of the stress (due to annealing effect). A low etching rate of the amorphous silicon carbide layer was noticed for wet etching in KOH 30% at 80 °C (around 13 A/min) while in HF 49% the layer is practically inert. A very slow etching rate of amorphous silicon carbide layer in XeF₂ -7 A/min- was observed. The paper presents an example of this application: PECVD-amorphous silicon carbide cantilevers fabricated using surface micromachining by dry-released technique in XeF₂.     

Potential anticancer agents. XXVI. Spin Labelled Nitrosoureas

In order to obtain more information about the in vivo mechanism of action of nitrosoureas, the synthesis of spin labelled nitrosoureas derived from 1-oxyl-2.2.6.6-tetramethyl-4-aminopiperidine was undertaken. The synthesis of four spin labelled ureas 4a–4d was reported as well as two spin labelled nitrosoureas:1-methyl-3-(2′.2′.6′.6.′-tetramethyl-piperidin-4′-yl-1′-oxyl)-1-nitrosourea( 9a ) and 1-(2′-chloroethyl)-3-(2″,2″.6″.6″-tetramethyl-piperidin-4″-yl-1″-oxyl)-nitrosourea (9b) . Their e.s.r. spectra were recorded. None of these compounds proved to be active against L1210.     

Unified verification and monitoring of executable UML specifications

Software and Systems Modeling - The increasing complexity of embedded systems renders software verification more complex, requiring monitoring and formal techniques, like model-checking. However,...     

Review: Scalable Fabrication of Polymeric Nanofibers from Nano- Spinning Techniques to Emerging Applications

综述：规模化制备聚合物纳米纤维，从纳米纺丝技术到新兴应用

陆腱^?，胡泽旭^?，王倩倩，Matteo Ciprian，费翔^*，朱美芳^*

（纤维材料改性国家重点实验室，东华大学 材料科学与工程学院，上海 201620）

中文说明

由于纳米纤维具有高比表面积、高孔隙率、物理/化学改性多样化、易于实现杂化的特性，对纳米纤维的研究越来越受到产业界和学术界的关注。本文综述了近年来聚合物纳米纤维（PNFs）的制备技术进展，重点介绍了PNF的规模化生产及其在新兴领域的应用。首先简要介绍了制备PNFs的加工工艺和设备，说明了聚合物前驱体、加工工艺参数和环境条件对纳米纤维成形的影响，并讨论了过去在工业生产中制备PNF所取得的成就和面临的挑战。同时综述了制备多功能复合纳米纤维的杂化方法，包括引入有机组分进行改性、负载功能性无机纳米材料、在纳米纤维表面或内部负载生物活性组分等。基于以上杂化方法和功能性，讨论了聚合物纳米纤维以环境保护和生物医用为主的新兴应用。最后对本文的研究成果进行了总结和展望。

关键词：纳米纤维，聚合物，纳米纺丝技术，杂化，应用

     

Rolling Friction in a Micro Tribosystem

Pin-on-disc apparatus was used to investigate the effect of temperature on the dry sliding friction characteristics of a Zr-based bulk metallic glass (BMG) near its glass transition temperature (T _g = 625 K) (an analogous phenomenon in crystalline metals called the ductile-brittle transition). Unexpected variation in frictional behavior was observed in the temperature range of 603–643 K, suggesting that the glass transition and formation of protective oxide layers played roles in the tribological properties of BMG. An explanation of the behavior is given based on Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) analysis.     

Radio frequency heating pasteurization of pine wood nematode (Bursaphelenchus xylophilus) infected wood

The research was aimed to establish whether dielectric heating at radio frequencies (RF)??an alternative method to ozone-depleting methyl bromide fumigation and to convective heating??could bring green lodgepole pine boards infested with pinewood nematodes (PWN) to pasteurization requirements. Artificially infected specimens were treated using a laboratory RF oven and post-treatment nematode survival levels were assessed. Both tested combinations of?56°C/30?min and 60°C/15?min were effective in eradicating PWN. A?power density of 50?kW/m³ maintained for 75?minutes fully pasteurized all the tested boards and proved to be the right combination if no temperature sensors are used. The data gathered supports the idea that pasteurization by RF heating is a reliable and swift alternative treatment to fumigation and convective heat treatment.