Memory-based controller design for neutral time-delay systems with input saturations: A novel delay-dependent polytopic approach

In this paper, a new memory-based control problem is addressed for neutral systems with time-varying delay, input saturations and energy bounded disturbances. Attention is focused on the design of a memory-based state feedback controller such that the closed-loop system achieves the desirable performance indices including the boundedness of the state trajectories, the H_∞ disturbance rejection/attenuation level as well as the asymptotic stability. By using the combination of a novel delay-dependent polytopic approach, augmented Lyapunov–Krasovskii functionals and some integral inequalities, delay-dependent sufficient conditions are first proposed in terms of linear matrix inequalities. Then, three convex optimization problems are formulated whose aims are to, respectively, maximize the disturbance tolerance level, minimize the disturbance attenuation level and maximize the initial condition set. Finally, simulation examples demonstrate the effectiveness and benefits of the obtained results.     

Membrane-integrated microfluidic device for high-resolution live cell imaging

The design and fabrication of a membrane-integrated microfluidic cell culture device (five layers,≤500 μm total thickness) developed for high resolution microscopy is reported here. The multi-layer device was constructed to enable membrane separated cell culture for tissue mimetic in vitro model applications and pharmacodynamic evaluation studies. The microdevice was developed via a unique combination of low profile fluidic interconnect design, substrate transfer methodology, and wet silane bonding. To demonstrate the unique high resolution imaging capability of this device, we used oil immersion microscopy to image stained nuclei and mitochondria in primary hepatocytes adhered to the incorporated membrane     

The crucial role of theoretical scholarship for learning design and technology

Educational technology research and development -     

Preservice teachers’ use of contrasting cases in mathematics instruction

Drawing comparisons between students’ alternative solution strategies to a single mathematics problem is a powerful yet challenging instructional practice. We examined 80 preservice teachers’ when asked to design a short lesson when given a problem and two student solutions—one correct and one incorrect. These micro-teaching events were videotaped and coded, revealing that fewer than half of participants (43%) made any explicit comparison or contrasts between the two solution strategies. Those who did were still not likely to use additional support strategies to draw students’ attention to key elements of the comparison. Further, correlations suggest that participants’ mathematical content knowledge may be related to whether participants’ showed contrasting cases but not to whether they used specific pedagogical cues to support those comparisons. While these micro-teaching events differ from the interactive constraints of a classroom, they reveal that participants did not immediately orient toward differing student solutions as a discussion opportunity, and that future instruction on contrasting cases must highlight the utility of this practice.     

The Benjamin Franklin Medal in Life Science presented to Judah Folkman

The Franklin Institute, Philadelphia, Pennsylvania awarded the 2001 Benjamin Franklin Medal in Life Science to Judah Folkman for his founding of the field of angiogenesis research and demonstration that angiogenesis is a necessary factor in the conversion of abnormal cells to malignant tumors.     

Comparative evaluation of ultramicro—and macro-chemo enzyme based assays of glucose, cholesterol and triglycerides

A comparison of the absorbance, enzyme/substrate concentration, reaction efficiency and sensitivity has been made for enzyme-based clinical chemistry assays, using a conventional colorimeter versus a strip-microwell reader, in order to establish the value of ultra-microchemical procedure, with reaction volume 87 μl (light path length=0.25 cm). By utilizing commercial kits available for the quantitation of serum glucose, cholesterol and triglycerides, it has been established that the micro method is highly cost effective (9–30 fold), reproducible and sensitive. Comparison of blood drawn by a finger prick (capillary) and venipuncture for normal and pathological specimens show reproducibility between different laboratory technologists and in reference with the values reported by an accredited reference laboratory. Since the micro method uses very little serum, it is most suitable for analyses of small smaples, from large population-based field trials. However, the assay range has to be titrated for each commercial kit to establish the enzyme/substrate equivalence.