Non-linearity of the interactions between bottom-up and top-down signals in multistable visual perception

Summary Both bottom-up sensory information and top-down influences contribute to the perception processes. We studied the perceptual alternations of a multistable ambiguous pattern. We observed that it is possible to interfere on the process of the perception alternance by means of subliminal visual stimuli, which either contrast or second the previous perception. We investigated also the effect of the top-down volitional factor on the perceptual alternation. By using a combination of such top-down factor and bottom-up stimulation, we ascertained that a non-linear type of interaction occurs between the two above factors. Paper presented at the International Workshop ?Fluctuations in Physics and Biology: Stochastic Resonance, Signal Processing and Related Phenomena?, Elba, 5–10 June 1994.     

Evaluation of low-dose irradiation on microbiological quality of white carrots and string beans

The minimally processed food provided the consumer with a product quality, safety and practicality. However, minimal processing of food does not reduce pathogenic population of microorganisms to safe levels. Ionizing radiation used in low doses is effective to maintain the quality of food, reducing the microbiological load but rather compromising the nutritional values and sensory property. The association of minimal processing with irradiation could improve the quality and safety of product. The purpose of this study was to evaluate the effectiveness of low-doses of ionizing radiation on the reduction of microorganisms in minimally processed foods. The results show that the ionizing radiation of minimally processed vegetables could decontaminate them without several changes in its properties.     

Trends in computational simulations of electrochemical processes under hydrodynamic flow in microchannels

Computational modeling and theoretical simulations have recently become important tools for the development, characterization, and validation of microfluidic devices. The recent proliferation of commercial user-friendly software has allowed researchers in the microfluidics community, who might not be familiar with computer programming or fluid mechanics, to acquire important information on microsystems used for sensors, velocimetry, detection for microchannel separations, and microfluidic fuel cells. We discuss the most popular computational technique for modeling these systems—the finite element method—and how it can be applied to model electrochemical processes coupled with hydrodynamic flow in microchannels. Furthermore, some of the limitations and challenges of these computational models are also discussed.     

Evaluation of γ-radiation on oolong tea odor volatiles

The aim of this study was to evaluate the gamma radiation effects on odor volatiles in oolong tea at doses of 0, 5, 10, 15 and 20 kGy. The volatile organic compounds were extracted by hydrodistillation and analyzed by GC/MS. The irradiation has a large influence on oolong tea odor profile, once it was identified 40% of new compounds after this process, the 5 kGy and 20 kGy were the doses that degraded more volatiles found naturally in this kind of tea and the dose of 10 kGy was the dose that formed more new compounds. Statistical difference was found between the 5 kGy and 15 kGy volatile profiles, however the sensorial analysis showed that the irradiation at dose up 20 kGy did not interfere on consumer perception.     

Flow characterization of a microfluidic device to selectively and reliably apply reagents to a cellular network

A three-dimensional microfluidic device has been successfully fabricated and the flow streams characterized for eventual use in studying communication in an in vitro network of nerve cells. The microfluidic system is composed of two layers of channels: a lower layer for the delivery of pharmacological solutions and an upper layer of channels used to direct the flow of the pharmacological solution streams and perfuse the cells with media and nutrients. Flow profiles have been characterized with computational fluid dynamics simulations, confocal fluorescence microscopy, and carbon-fiber amperometry, which have been used to map changes in flow profiles at different bulk flow rates. Ultimately, the microfluidic system and incorporated cell network will show how networked neurons adapt, compensate, and recover after being exposed to different chemical compounds.     

Recent advances in capillary electrophoretic analysis of individual cells

Because variability exists within populations of cells, single-cell analysis has become increasingly important for probing complex cellular environments. Capillary electrophoresis (CE) is an excellent technique for identifying and quantifying the contents of single cells owing to its small volume requirements and fast, efficient separations with highly sensitive detection. Recent progress in both whole-cell and subcellular sampling has allowed researchers to study cellular function in the areas of neuroscience, oncology, enzymology, immunology, and gene expression.      

A periodic review policy for a coordinated single vendor-multiple buyers supply chain with controllable lead time and distribution-free approach

4OR - In this paper, we study a single vendor-multiple buyer integrated inventory model with controllable lead time and backorders-lost sales mixture. Each buyer adopts a periodic review policy in...