An investigation of the search behaviour associated with Ingwersen’s three types of information needs

We report a naturalistic interactive information retrieval (IIR) study of 18 ordinary users in the age of 20–25 who carry out everyday-life information seeking (ELIS) on the Internet with respect to the three types of information needs identified by Ingwersen (1986): the verificative information need (VIN), the conscious topical information need (CIN), and the muddled topical information need (MIN). The searches took place in the private homes of the users in order to ensure as realistic searching as possible. Ingwersen (1996) associates a given search behaviour to each of the three types of information needs, which are analytically deduced, but not yet empirically tested. Thus the objective of the study is to investigate whether empirical data does, or does not, conform to the predictions derived from the three types of information needs. The main conclusion is that the analytically deduced information search behaviour characteristics by Ingwersen are positively corroborated for this group of test participants who search the Internet as part of ELIS.     

A simple method of fabricating mask-free microfluidic devices for biological analysis

We report a simple, low-cost, rapid, and mask-free method to fabricate two-dimensional (2D) and three-dimensional (3D) microfluidic chip for biological analysis researches. In this fabrication process, a laser system is used to cut through paper to form intricate patterns and differently configured channels for specific purposes. Bonded with cyanoacrylate-based resin, the prepared paper sheet is sandwiched between glass slides (hydrophilic) or polymer-based plates (hydrophobic) to obtain a multilayer structure. In order to examine the chip’s biocompatibility and applicability, protein concentration was measured while DNA capillary electrophoresis was carried out, and both of them show positive results. With the utilization of direct laser cutting and one-step gas-sacrificing techniques, the whole fabrication processes for complicated 2D and 3D microfluidic devices are shorten into several minutes which make it a good alternative of poly(dimethylsiloxane) microfluidic chips used in biological analysis researches.     

Facile fabrication processes for hydrogel-based microfluidic devices made of natural biopolymers

We present facile strategies for the fabrication of two types of microfluidic devices made of hydrogels using the natural biopolymers, alginate, and gelatin as substrates. The processes presented include the molding-based preparation of hydrogel plates and their chemical bonding. To prepare calcium-alginate hydrogel microdevices, we suppressed the volume shrinkage of the alginate solution during gelation using propylene glycol alginate in the precursor solution along with sodium alginate. In addition, a chemical bonding method was developed using a polyelectrolyte membrane of poly-L-lysine as the electrostatic glue. To prepare gelatin-based microdevices, we used microbial transglutaminase to bond hydrogel plates chemically and to cross-link and stabilize the hydrogel matrix. As an application, mammalian cells (fibroblasts and vascular endothelial cells) were cultivated on the microchannel surface to form three-dimensional capillary-embedding tissue models for biological research and tissue engineering.     

Advances in three-dimensional rapid prototyping of microfluidic devices for biological applications

The capability of 3D printing technologies for direct production of complex 3D structures in a single step has recently attracted an ever increasing interest within the field of microfluidics. Recently, ultrafast lasers have also allowed developing new methods for production of internal microfluidic channels within the bulk of glass and polymer materials by direct internal 3D laser writing. This review critically summarizes the latest advances in the production of microfluidic 3D structures by using 3D printing technologies and direct internal 3D laser writing fabrication methods. Current applications of these rapid prototyped microfluidic platforms in biology will be also discussed. These include imaging of cells and living organisms, electrochemical detection of viruses and neurotransmitters, and studies in drug transport and induced-release of adenosine triphosphate from erythrocytes.     

High throughput fabrication of disposable nanofluidic lab-on-chip devices for single molecule studies

An easy method is introduced allowing fast polydimethylsiloxane (PDMS) replication of nanofluidic lab-on-chip devices using accurately fabricated molds featuring cross-sections down to 60 nm. A high quality master is obtained through proton beam writing and UV lithography. This master can be used more than 200 times to replicate nanofluidic devices capable of handling single DNA molecules. This method allows to fabricate nanofluidic devices through simple PDMS casting. The extensions of YOYO-1 stained bacteriophage T4 and λ−DNA inside these nanochannels have been investigated using fluorescence microscopy and follow the scaling prediction of a large, locally coiled polymer chain confined in nanochannels.     

Systematic characterization of degas-driven flow for poly(dimethylsiloxane) microfluidic devices

Degas-driven flow is a novel phenomenon used to propel fluids in poly(dimethylsiloxane) (PDMS)-based microfluidic devices without requiring any external power. This method takes advantage of the inherently high porosity and air solubility of PDMS by removing air molecules from the bulk PDMS before initiating the flow. The dynamics of degas-driven flow are dependent on the channel and device geometries and are highly sensitive to temporal parameters. These dependencies have not been fully characterized, hindering broad use of degas-driven flow as a microfluidic pumping mechanism. Here, we characterize, for the first time, the effect of various parameters on the dynamics of degas-driven flow, including channel geometry, PDMS thickness, PDMS exposure area, vacuum degassing time, and idle time at atmospheric pressure before loading. We investigate the effect of these parameters on flow velocity as well as channel fill time for the degas-driven flow process. Using our devices, we achieved reproducible flow with a standard deviation of less than 8% for flow velocity, as well as maximum flow rates of up to 3 nL∕s and mean flow rates of approximately 1-1.5 nL∕s. Parameters such as channel surface area and PDMS chip exposure area were found to have negligible impact on degas-driven flow dynamics, whereas channel cross-sectional area, degas time, PDMS thickness, and idle time were found to have a larger impact. In addition, we develop a physical model that can predict mean flow velocities within 6% of experimental values and can be used as a tool for future design of PDMS-based microfluidic devices that utilize degas-driven flow.     

定量专利分析的样本选取与数据清洗

定量专利分析工作离不开正确的样本选取和严谨的数据清洗。作为定量专利分析的前提和基础,样本选取和数据清洗影响着专利分析的结论,并决定着专利分析的效果。样本选取和数据清洗的基本步骤是:选择数据来源、限定数据范围、生成样本空间、数据规范、字段拆分以及数据标引。     

Controlled electroporation of the plasma membrane in microfluidic devices for single cell analysis

Chemical cytometry on a single cell level is of interest to various biological fields ranging from cancer to stem cell research. The impact chemical cytometry can exert in these fields depends on the dimensionality of the retrievable analytes content. To this point, the number of different analytes identifiable and additionally their subcellular localization is of interest. To address this, we present an electroporation based approach for selective lysis of only the plasma membrane, which permits analysis of the dissolved cytoplasm, while reducing contributions from the nucleus and membrane bound fractions of the cell analytes. The use of 100 μs long pulse and a well defined DC electric field gradient of ∼4.5 kV·cm⁻¹ generated by 3D electrodes initiates release of a cytoplasm marker in ≪1 s, while retaining nuclear fluorescence markers.     

Information management for investigation and prevention of white-collar crime

White-collar crime is financial crime committed by upper class members of society for personal or organizational gain. White-collar criminals are individuals who tend to be wealthy, highly educated, and socially connected, and they are typically employed by and in legitimate organizations. This article presents a stage of growth model for knowledge management systems to support investigation and prevention of white-collar crime in business organizations. The four stages are labelled investigator-to-technology, investigator-to-investigator, investigator-to-information and investigator-to-application, respectively.     

Use of a virtual wall valve in polydimethylsiloxane microfluidic devices for bioanalytical applications

A simple method for micromanipulation of liquids and∕or small groups of cells is presented in this study. Microfabricated sieving structures composed of PDMS (polydimethylsiloxane) were used to segregate aqueous solutions. This microfluidic valving scheme was an application of Cassie-Baxter wetting and was termed "virtual walls" as a nonsolid barrier exists at an air∕water interface. The manipulation of the virtual-air-wall valve was accomplished by controlling the strength of surface-tension and hydrostatic-pressure forces. Virtual walls with a range of feature sizes were designed and characterized by monitoring air and water displacement in response to hydrostatic pressure. Thresholds for the virtual-air-wall valves to be turned on or off were quantified. The walls could also be formed or dissipated by the focused microbeam of a pulsed laser. As an illustration of the virtual wall utility, a series of microfluidic applications were demonstrated. First, the capability of virtual walls to temporarily segregate liquids was integrated into a device utilized to establish a chemical gradient. In a second application, the arraying of nonadherent cells within individual aqueous cavities created by the virtual walls was demonstrated. Individual cells were also released from the cavities on demand using a focused microbeam. The virtual walls were simple and easy-to-fabricate without the requirement for surface treatment or precision alignment, and should find usage in bioanalytical applications.     

A practical guide for the fabrication of microfluidic devices using glass and silicon

This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow.     

A microfluidic platform for quantitative analysis of cancer angiogenesis and intravasation

Understanding the mechanism behind cancer metastasis is a major challenge in cancer biology. Several in vitro models have been developed to mimic a cancer microenvironment by engineering cancer–endothelial cell (EC) and cancer-stromal cell interactions. It has been challenging to realistically mimic angiogenesis, intravasation, and extravasation using macro-scale approaches but recent progress in microfluidics technology has begun to yield promising results. We present a metastasis chip that produce microvessels, where EC and stromal cells can be patterned in close proximity to tumor cells. The vessels are formed following a natural morphogenic process and have smooth boundaries with proper cell-cell junctions. The engineered microvessels are perfusable and have well-defined openings toward inlet and outlet channels. The ability to introduce cancer cells into different locations bordering to the microvessel wall allowed generation and maintenance of appropriate spatial gradients of growth factors and attractants. Cancer angiogenesis and its inhibition by anti-vascular endothelial growth factor (bevacizumab) treatment were successfully reproduced in the metastasis chip. Cancer intravasation and its modulation by treatment of tumor necrosis factor-α were also modeled. Compared to other models, the unique design of the metastasis chip that engineers a clear EC-cancer interface allows precise imaging and quantification of angiogenic response as well as tumor cell trans-endothelial migration. The metastasis chip presented here has potential applications in the investigation of fundamental cancer biology as well as in drug screening.     

优秀课堂教学质量奖量化评价方法的研究

科学准确地评价教学质量既能为学校管理层提供教师教学的可靠信息,也能激发老师本人不断改进教学方法。本研究从教师素质、教学态度、教学内容、教学方法以及教学效果等五个方面为观察点,提出同行量化评教的办法。同时结合学生评教的结果,综合评选出优秀课堂教学质量奖。还提出了提高课堂教学质量的建议。     

电能计量装置改造综合效益评价的研究

从经济、社会、管理和技术四个方面设计了电能计量装置改造综合效益的评价指标体系。将定性指标和定量指标相结合,采用熵权法结合专家权重建立了评价模型。具体案例说明了评价指标体系和模型的实用性以及有效性。     

Selection devices for user of an electronic encyclopedia: An empirical comparison of four possibilities

This study measured the speed, error rates, and subjective evaluation of arrow-jump keys, a jump-mouse, number keys, and a touch screen in an interactive encyclopedia. A summary of previous studies comparing selection devices and strategies is presented to provide the background for this study. We found the touch screen to be the fastest in time, the least accurate but the overall favorite of the participants. The results are discussed and improvements are suggested accordingly.     

An investigation into the application of ensemble learning for entailment classification

Textual entailment is a task for which the application of supervised learning mechanisms has received considerable attention as driven by successive Recognizing Data Entailment data challenges. We developed a linguistic analysis framework in which a number of similarity/dissimilarity features are extracted for each entailment pair in a data set and various classifier methods are evaluated based on the instance data derived from the extracted features. The focus of the paper is to compare and contrast the performance of single and ensemble based learning algorithms for a number of data sets. We showed that there is some benefit to the use of ensemble approaches but, based on the extracted features, Naïve Bayes proved to be the strongest learning mechanism. Only one ensemble approach demonstrated a slight improvement over the technique of Naïve Bayes.