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981.
This paper presents an assumption/commitment specification technique and a refinement calculus for networks of agents communicating asynchronously via unbounded FIFO channels in the tradition of Kahn. We define two types of assumption/commitment specifications, namely simple and general specifications. It is shown that semantically, any deterministic agent can be uniquely characterized by a simple specification, and any nondeterministic agent can be uniquely characterized by a general specification. We define two sets of refinement rules, one for simple specifications and one for general specifications. The rules are Hoare-logic inspired. In particular the feedback rules employ invariants in the style of a traditional while-rule. Both sets of rules have been proved to be sound and also (semantic) relative complete. Conversion rules allow the two logics to be combined. This means that general specifications and the rules for general specifications have to be introduced only at the point in a system development where they are really needed. 相似文献
982.
JO Larsson G Aurelius L Nordberg PA Rydelius R Zetterstr?m 《Canadian Metallurgical Quarterly》1996,85(12):1450-1455
Home visiting is a part of the Swedish child health surveillance programme. In the present study, part of a longitudinal prospective project, the predictive power of observations at home visits to 338 newborn babies was evaluated. The regular home visit was made by the nurse at a Child Welfare Centre also using a check-list developed for this project. Her check-list assessments seemed valid in identifying families with stressful psychosocial conditions. When the general home situation was judged as "poor" or "dubious", the boys showed signs of a delayed mental development at 4-5 years of age. Assessments of "feeding problems" among boys were associated with behavioural problems at 4-5 years of age. The results underline the importance of an early home visit as a base for the developmental surveillance at Child Welfare Centres. However, the results of the home visit observations were not followed by any extra interventions at CWC. It seems the nurse should feel confident in her check-list judgement and initiate interventions where appropriate. 相似文献
983.
This study presents a method that uses a standing surface acoustic wave (SSAW) to continuously separate particles in a size-gradient
manner in a microchannel flow. The proposed method was applied to a colloidal suspension containing poly dispersed particles
with three different sizes (1, 5, and 10 μm) but the same density and compressibility. Particle suspension was focused hydrodynamically
at an entrance region, and particles were forced actively toward the side wall where SSAW-pressure nodes were generated by
two interdigital transducers (IDTs) across the channel. The particles placed in the middle stream, in which the shear rate
was minimized, were separated successfully in a size-gradient manner by acoustic force. In addition, this study further developed
an analytical model to predict the displacement of particles in microchannel flow by considering viscous, acoustic, and diffusive
forces. The predicted values of particle displacement showed excellent agreement with the experimental results, and diffusion
was found to be important and not negligible. The advantage of this method is to minimize the shear rate on particles, which
would be useful for potential applications of shear-dependent cells such as platelets. 相似文献
984.
Changchun?Liu Michael?G.?Mauk Haim?H.?BauEmail author 《Microfluidics and nanofluidics》2011,11(2):209-220
An inexpensive, disposable, integrated, polymer-based cassette for loop-mediated isothermal amplification (LAMP) of target
nucleic acids was designed, fabricated, and tested. The LAMP chamber was equipped with single-use, thermally actuated valves
made with a composite consisting of a mixture of PDMS and expandable microspheres. The effect of the composite composition
on its expansion was investigated, and the valve’s performance was evaluated. In its closed state, the valve can hold pressures
as high as 200 kPa without any significant leakage. Both the LAMP chamber and the valves were actuated with thin film heaters.
The utility of the cassette was demonstrated by carrying out LAMP of Escherichia coli DNA target and reverse transcribed loop meditated isothermal amplification (RT-LAMP) of RNA targets. The amplicons were detected
in real time with a portable, compact detector. The system was capable of detecting as few as 10 target molecules per sample
in well under 1 h. The portable, integrated cassette system described here is particularly suited for applications at the
point of care and in resource-poor countries, where funds and trained personnel are in short supply. 相似文献
985.
Chia-Hsien?Yeh Ying-Chieh?Chen Yu-Cheng?LinEmail author 《Microfluidics and nanofluidics》2011,11(3):245-253
This study successfully uses the micro-mixers and flow-focusing devices, which are integrated into a gradient-microfluidic
droplet generator, to generate the different sizes of the droplets with different concentrations simultaneously and applies
these microcapsules for drug release. The sizes of these four types of droplet with different concentrations are uniformity
with a coefficient of variation less than 5% and can be precisely controlled by adjusting the water phase flow rate and oil
phase flow rate. Moreover, Ca-alginate microcapsules with different concentrations of the bovine serum albumin are used for
uniform size drug release, and the Ca-alginate microcapsule size is from 60 to 105 μm in diameter. This developed microfluidic
chip has the advantages of actively controlling the droplet diameter, simultaneously generating uniform-sized droplets with
different concentrations, and having a simple process and a high throughput. This preparation approach for Ca-alginate microcapsules
of four different concentrations will provide many potential applications for drug delivery and pharmaceutical area. 相似文献
986.
Marc Karle Johannes W?hrle Junichi Miwa Nils Paust G��nter Roth Roland Zengerle Felix von Stetten 《Microfluidics and nanofluidics》2011,10(4):935-939
We demonstrate controlled transport of superparamagnetic beads in the opposite direction of a laminar flow. A permanent magnet
assembles 200 nm magnetic particles into about 200 μm long bead chains that are aligned in parallel to the magnetic field
lines. Due to a magnetic field gradient, the bead chains are attracted towards the wall of a microfluidic channel. A rotation
of the permanent magnet results in a rotation of the bead chains in the opposite direction to the magnet. Due to friction
on the surface, the bead chains roll along the channel wall, even in counter-flow direction, up to at a maximum counter-flow
velocity of 8 mm s−1. Based on this approach, magnetic beads can be accurately manoeuvred within microfluidic channels. This counter-flow motion
can be efficiently be used in Lab-on-a-Chip systems, e.g. for implementing washing steps in DNA purification. 相似文献
987.
In this paper, we study singularly perturbed impulsive stochastic delay differential systems (SPISDDSs). By establishing an
L-operator delay differential inequality and using the stochastic analysis technique, we obtain some sufficient conditions
ensuring the exponential p-stability of any solution of SPISDDSs for sufficiently small ɛ > 0. The results extend and improve the earlier publications. An example is also discussed to illustrate the efficiency of
the obtained results. 相似文献
988.
Jin-Xing?LinEmail author Xian-Lin?Zhao Shu-Min?Fei 《International Journal of Control, Automation and Systems》2011,9(2):218-227
This paper considers the problem of exponential stability for continuous-time singular systems with interval time-varying
delay. By defining a novel Lyapunov-Krasovskii function and giving a tighter upper bound of its derivative, a new delay-range-dependent
exponential admissibility criterion, which not only guarantees the regularity, absence of impulses and exponential stability
of the system but also gives the estimates of decay rate and decay coefficient, is established in terms of linear matrix inequality
(LMI). The resulting criterion has advantages over the result previously reported by Haidar et al. [17] in that it involves fewer matrix variables but has less conservatism, which is established theoretically. Examples are
provided to demonstrate the advantage of the proposed criterion. 相似文献
989.
We present a non-intrusive molecular dye based method, i.e., laser-induced fluorescence photobleaching anemometer (LIFPA),
to significantly increase temporal resolution (TR) for velocity measurement of fast transient electrokinetic flows. To our
knowledge, the TR has been for the first time achieved to 5–10 μs, about 100 times better than that published from state-of-the-art
micro particle image velocimetry (μPIV), which is currently the most widely used velocimetry in the microfluidics community.
The new method provides us with new opportunities to study experimentally the fundamental phenomena of unsteady electrokinetics
(EK) and to validate relevant theoretical models. One application of the new method is demonstrated by measuring the rise
time of DC electroosmotic flows (EOFs) in a microcapillary of 10 μm in diameter. 相似文献
990.
Thomas?Lavergne Tanguy?Urvoy Fran?ois?YvonEmail author 《Language Resources and Evaluation》2011,45(1):25-43
Fake content is flourishing on the Internet, ranging from basic random word salads to web scraping. Most of this fake content
is generated for the purpose of nourishing fake web sites aimed at biasing search engine indexes: at the scale of a search
engine, using automatically generated texts render such sites harder to detect than using copies of existing pages. In this
paper, we present three methods aimed at distinguishing natural texts from artificially generated ones: the first method uses
basic lexicometric features, the second one uses standard language models and the third one is based on a relative entropy
measure which captures short range dependencies between words. Our experiments show that lexicometric features and language
models are efficient to detect most generated texts, but fail to detect texts that are generated with high order Markov models.
By comparison our relative entropy scoring algorithm, especially when trained on a large corpus, allows us to detect these
“hard” text generators with a high degree of accuracy. 相似文献