Ultrasonic Monitoring of Material Degradation in FRP Composites

This research uses laser ultrasonic techniques to monitor a (directly measurable) ultrasonic property—frequency-dependent Rayleigh wave velocity (material dispersion)—and then relates changes in this acoustic property to changes in the material's properties (such as stiffness) that characterize damage. The subject material system is a thick, glass-reinforced, vinylester (thermosetting) fiber-reinforced polymer (FRP) composite. Laser ultrasonics is an ideal methodology to monitor changes in the Rayleigh phase (or group) velocity of this material because of its high fidelity, broad bandwidth, point source∕receiver, and noncontact nature. The experimental procedure consists of measuring a series of transient elastic waveforms in a thick FRP specimen and then operating on these waveforms with the 2D fast Fourier transform to develop the dispersion relationship for that specimen. Material degradation (damage) is introduced into these specimens with environmental aging, and the dispersion curves are used to quantitatively track changes in material properties as a function of degradation.     

A Civil Engineering Curriculum for the Future: The Georgia Tech Case

This paper presents the results of an undergraduate civil engineering curriculum revision at the Georgia Institute of Technology. The process of revision included a variety of important constituencies that provided important input into the adopted curriculum. The curriculum provides emphasis on civil engineering systems, technical communications, sustainability, and computer-based analysis and design. In addition, the paper discusses efforts to encourage students to pursue a masters degree and the use of distance learning technologies as a platform for instruction.     

Neutrophils,Cancer and Thrombosis: The New Bermuda Triangle in Cancer Research

Spontaneous venous thrombosis is often the first clinical sign of cancer, and it is linked to a worsened survival rate. Traditionally, tumor-cell induced platelet activation has been the main actor studied in cancer-associated-thrombosis. However, platelet involvement alone does not seem to be sufficient to explain this heightened pro-thrombotic state. Neutrophils are emerging as key players in both thrombus generation and cancer progression. Neutrophils can impact thrombosis through the release of pro-inflammatory cytokines and expression of molecules like P-selectin and Tissue Factor (TF) on their membrane and on neutrophil-derived microvesicles. Their role in cancer progression is evidenced by the fact that patients with high blood-neutrophil counts have a worsened prognosis. Tumors can attract neutrophils to the cancer site via pro-inflammatory cytokine secretions and induce a switch to pro-tumoral (or N2) neutrophils, which support metastatic spread and have an immunosuppressive role. They can also expel their nuclear contents to entrap pathogens forming Neutrophil Extracellular Traps (NETs) and can also capture coagulation factors, enhancing the thrombus formation. These NETs are also known to have pro-tumoral effects by supporting the metastatic process. Here, we strived to do a comprehensive literature review of the role of neutrophils as drivers of both cancer-associated thrombosis (CAT) and cancer progression.     

责任制与业绩测量法并非万能管理手段

很难想象在商业活动中,会有过多的责任一说. 20年前,马里兰大学的爱德·洛克教授研究了能够带来更好成果的4种最流行的管理手段.其中,确立与责任挂钩的目标这一手段高居榜首,它是经理人可以实施的最有效的战略,可以把业绩平均提高16%.     

分享目标,推动员工全身心达成任务的伟大力量

我们并不在一个完美的世界里工作.问题是有什么东西挡住了我们的去路,一个我们没有看到的绊脚石. 这意味着经理人需要做的不仅仅是执行和清除障碍.领导们必须帮助员工找到一个专注于工作的理由,使他们战胜困难并发挥必要的主动性,确保他们达到组织的期望.     

Polyfluorinated compounds: past, present, and future

Interest and concern about polyfluorinated compounds (PFCs), such as perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and an increasing number of other related compounds is growing as more is learned about these ubiquitous anthropogenic substances. Many of these compounds can be toxic, and they are regularly found in the blood of animals and humans worldwide. A great deal of research has been conducted in this area, but a surprising amount remains unknown about their distribution in the environment and how people ultimately become exposed. The utility of these compounds seems to ensure their continued use in one form or another for the foreseeable future, presenting a long-term challenge to scientists, industry leaders, and public health officials worldwide.     

An automated noncontact deposition interface for liquid chromatography matrix-assisted laser desorption/ionization mass spectrometry

A new multichannel deposition system was developed for off-line liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry (LC/MALDI-MS). This system employs a pulsed electric field to transfer the eluents from multiple parallel columns directly onto MALDI targets without the column outlets touching the target surface. The deposition device performs well with a wide variety of solvents that have different viscosities, vapor pressures, polarities, and ionic strengths. Surface-modified targets were used to facilitate concentration and precise positioning of samples, allowing for efficient automation of high-throughput MALDI analysis. The operational properties of this system allow the user to prepare samples using MALDI matrixes whose properties range from hydrophilic to hydrophobic. The latter, exemplified by alpha-cyano-4-hydroxycinnamic acid, were typically processed with a multistep deposition method consisting of precoating of individual spots on the target plate, sample deposition, and sample recrystallization steps. Using this method, 50 amol of angiotensin II was detected reproducibly with high signal-to-noise ratio after LC separation. Experimental results show that there is no significant decrease in chromatographic resolution using this device. To assess the behavior of the apparatus for complex mixtures, 5 microg of a tryptic digest of the cytosolic proteins of yeast was analyzed by LC/MALDI-MS and more than 13,500 unique analytes were detected in a single LC/MS analysis.     

Biofeedback and behavioral medicine: Treating the symptom, the syndrome, or the person?

Suggests that if behavioral medicine is to fulfill its promise as a valid and effective contributor to the health care field, its practitioners must face a number of theoretical and practical realities. The author reviews the pitfalls and potentialities of a number of behavioral medicine subdisciplines, such as biofeedback, relaxation, coping skills training, and risk-behavior management. The importance of a solid background in the psychobiological sciences is emphasized, as is the need to understand and respect individual differences in the patients who present for treatment with ostensibly similar symptoms and syndromes. Finally, the role of behavioral medicine in the broader context of health and personality is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

P2P网络中沉默型蠕虫传播建模与分析

蠕虫给 Internet 带来巨大威胁,给作为 Internet 覆盖网的P2P网络带来的威胁更大,这主要是由P2P网络本身的特点决定的(就是这些特点为用户带来巨大方便).考虑到威胁P2P网络的3种蠕虫中沉默型蠕虫传播模型还没有被提出(其他2种分别为被动型蠕虫和主动型蠕虫)和沉默型蠕虫的巨大危害性,提出了沉默型蠕虫的传播模型和免疫模型,并基于该模型推导出了沉默型蠕虫不会流行的条件.为了考查各个P2P参数对蠕虫传播的影响和从实践上验证推导出的蠕虫不会流行的条件,使用Matlab进行了大量仿真实验.实验表明,理论推导出的蠕虫不会流行的条件是正确的;实验还进一步表明,蠕虫的流行程度是由流行指数来决定的,这为提出蠕虫控制策略提供了依据.通过对决定流行指数的几个参数的分析表明,在发现蠕虫时迅速降低下载率是补丁发布前控制蠕虫最有效的办法.