Single-frequency travelling-wave erbium-doped fibre loop laser

A novel erbium-doped fibre laser cavity configuration with produces single-longitudinal-mode operation with less than 10 kHz linewidth is reported. The fibre laser operates in a travelling-wave mode which prevents spatial holeburning from occurring. A principal advantage of the configuration is that it allows the precise and stable setting of the lasing wavelength.<>     

Reactive ion etching of Ta-Si-N diffusion barriers in CHF3+O2

Reactive ion etching of Ta₃₆Si₁₄N₅₀ diffusion barrier layers was performed in CHF₃+O₂ plasmas. Etch depths and rates were determined as a function of etch gas composition, cathode power, and etching time. Etching proceeds only after an initial delay which depends on gas composition and cathode power. This delay is attributed to the presence of a native surface oxide which must first be removed before etching can commence. Maximum etch rate was attained at 62.5% O₂ concentration, which also corresponds to minimum delay     

What do I do now: suggestions for the frustrated mid-career professional

Librarians, like most professionals, may arrive at a stage in their careers when they start questioning themselves about their job satisfaction and importance. The reasons are many, from not being challenged by their work to abrupt changes in the workplace dictated by management and the economy. At this stage, professionals may begin to feel unappreciated by management and not in control of their work environment. In this piece, I offer some suggestions that could help mid-career librarians to re-energize themselves and survive in a workplace that is in constant flux. How you react to the anxiety of "job disconnect" will affect the rest of your career life. Should you become more proactive at your job, increasing your responsibility and value to your institution? What does your personality have to do with how you adjust to management changes? Does tenure fit into this equation? Should you even think about changing your job at this stage of your career? What other factors could "spice" up your career? Specific strategies and options for each of these questions will be discussed.     

The effect of spherical projectile speed in ricochet off water and sand

Experimental results are reported for the ricochet of steel and duralumin spheres ( and 1 in. dia.), from shallow depths of water and dry sand. The critical angle for ricochet off water is shown to increase with speed to approach the theoretical limit of . For ricochet off sand the critical angle decreases with speed but a cut-off angle exists, , for which no ricochet occurs at any speed.     

A Full Electromagnetic Analysis of Grooved-Dielectric Fresnel Zone Plate Antennas for Microwave and Millimeter-Wave Applications

Grooved-dielectric, phase-correcting, Fresnel zone plate antennas are analyzed using the body-of-revolution finite-difference time-domain (BOR-FDTD) method. Parametric studies of the focusing ability of these antennas are performed to examine the effects of the focal length, diameter, number of zones, and the thickness of the lens, as well as the number of phase corrections per zone. The results of these studies are presented as design graphs and are used to lend insight into the focusing mechanism of phase-correcting zone plates. The BOR-FDTD analysis is validated by comparison with previous measurements.     

无铅-电路板线路互连接点IST信赖度测试

在过去两年中,PWB的无铅制程已有稳定变化,无铅影响力在PWB设计、制造及组装过程中日趋重要。有越来越多的高密度互连应力产品,多是用一般易取得的材料制造,HDI产品逐渐增加,组装时常用的材料现在已经经由热循环测试来评估其信赖性,接着使材料通过多次高温无铅制程及重工的测试。     

Sustained‐Release Synthetic Biomarkers for Monitoring Thrombosis and Inflammation Using Point‐of‐Care Compatible Readouts

Postoperative infection and thromboembolism represent significant sources of morbidity and mortality but cannot be easily tracked after hospital discharge. Therefore, a molecular test that could be performed at home would significantly impact disease management. The laboratory has previously developed intravenously delivered “synthetic biomarkers” that respond to dysregulated proteases to produce a urinary signal. These assays, however, have been limited to chronic diseases or acute diseases initiated at the time of diagnostic administration. Here, a subcutaneously administered sustained‐release system, using small poly(ethylene glycol) scaffolds (<10 nm) to promote diffusion into the bloodstream over a day, is formulated. The utility of a thrombin sensor to identify thrombosis and an Matrix metalloproteinase (MMP) sensor to measure inflammation is demonstrated. Finally, a companion paper ELISA (Enzyme‐linked immunosorbent sssay), using printed wax barriers, with nanomolar sensitivity for urinary reporters for point‐of‐care detection is developed. The approach for subcutaneous delivery of nanosensors combined with urinary paper analysis may enable facile monitoring of at‐risk patients.     

Planar InP/InGaAs avalanche photodetector with integrated dielectric wavelength filter

Patterned bandpass dielectric interference filters with centre wavelengths around 1.3 mu m have been applied to top-entry photodiodes to produce high-speed, high-responsivity, photodetectors for wavelength division multiplexing. The measured responsivity exceeded 25 A/W with a full width half maximum of 19 nm and peak rejection of over 25 dB.<>     

Effective elastic properties of randomly distributed void models for porous materials

Many 2D analytical models are available for estimating the effective elastic properties of porous materials. Most of these models adopt circular voids of a uniform diameter in superlattice arrays, such as unit void or periodically positioned models. There are two principal issues in a realistic representation of porous materials: the random distribution of a statistically sufficiently large number of voids in the model, and the random distribution of the size and position of the voids. Numerical schemes such as the FEM or the BEM have also been presented to cater for regular patterned circular voids. However, due to the large number of elements needed to produce sufficient accuracy for the curved boundary of circular voids or modelling a statistically sufficient number of voids with a random distribution in both the void size and the position, no such model has yet been produced.Modelling based on an FEM approach using a simplified approximation for void geometry is proposed here for the calculation of the effective elastic properties of porous solids. A plane strain model of a square geometry is adopted for a 2D array of voids. This simplified square shape allows a large number of voids to be simulated with a random distribution for both void sizes and their locations. The problem of anisotropy, which arises from the square shape, is discussed. It is verified that along the two principal directions (parallel to the sides of the square voids), the elastic properties remain the same as those predicted by using a circular void geometry. This square-shaped approximation, with its reduced requirement for FE analysis, has the potential to be extended to 3-dimensional modelling for a realistic simulation of engineering materials.     

测量不可测的:与可步行性相关的城市设计品质

本研究试图全面客观地衡量城市街道环境的与人们感受有关的品质.使用专家小组评级的方法,使得根据街道及其边缘的物质环境特征来衡量城市设计的五个品质——意象、围合空间、人的尺度、透明度和复杂性——成为可能.可操作的定义并不总与定性的定义相一致,可操作定义针对城市设计品质(urban design qualities)的性质提供了新见解.本研究的直接目的是为研究者提供(这五个城市设计品质的)可操作性定义,这样他们可以测量街道环境并测试其与步行行为之间的显著性联系.纽约市目前正在进行验证研究.最终目的是,根据本研究和其他后续研究的成果,来指导城市设计实践.