Biological laser action

The narrowing of the spectral linewidth and the increasing of the peak intensity characteristic of laser action were observed in emission spectra of dye-infused biological tissues. The tissue was infused with a solution of Rhodamine 640 perchlorate in ethanol and then excited with frequency-doubled Q-switched Nd:YAG laser pulses. The dependence of emission linewidth on the excitation radiant exposure and dye concentration was investigated. Laser action was also observed in biologically compatible fluorescein sodium dye dissolved in phosphate-buffered saline mixed with scattering polystyrene spheres. The sharp spectral peaks of laser action in tissues may find applications in the detection of superficial disease.     

Fluorescence spectroscopy of tissue: recovery of intrinsic fluorescence from measured fluorescence

We present a method for recovering the intrinsic fluorescence coefficient, defined as the product of the fluorophore absorption coefficient and the fluorescence energy yield, of an optically thick, homogeneous, turbid medium from a surface measurement of fluorescence and from knowledge of medium optical properties. The measured fluorescence signal is related to the intrinsic fluorescence coefficient by an optical property dependent path-length factor. A simple expression was developed for the path-length factor, which characterizes the penetration of excitation light and the escape of fluorescence from the medium. Experiments with fluorescent tissue phantoms demonstrated that intrinsic fluorescence line shape could be recovered and that fluorophore concentration could be estimated within ±15%, over a wide range of optical properties.     

Interactive evolution for cochlear implants fitting

Cochlear implants (CI) are devices that become more and more sophisticated and adapted to the need of patients, but at the same time they become more and more difficult to parameterize. After a deaf patient has been surgically implanted, a specialised medical practitioner has to spend hours during months to precisely fit the implant to the patient. This process is a complex one implying two intertwined tasks: the practitioner has to tune the parameters of the device (optimisation) while the patient’s brain needs to adapt to the new data he receives (learning). This paper presents a study that intends to make the implant more adaptable to environment (auditive ecology) and to simplify the process of fitting. Real experiments on volunteer implanted patients are presented, that show the efficiency of interactive evolution for this purpose.

A Software Agent Architecture for Network Management: Case Studies and Experience Gained

Current Network Management paradigms are rigid and lack flexibility. This makes the task of managing a highly evolving and dynamic network difficult to cope with. This paper presents the results of our work on Agent technology as a new paradigm for developing Network Management applications. First, we present our agent architecture that is built in a way that allows the agent to acquire new capabilities at runtime. Second, we present two case studies implemented with a prototype of this agent architecture. The first case study consists of an agent system in which faulty agents are automatically detected, their tasks then being reallocated to other agents, thus providing a fault-tolerant management system. The second case study deals with the configuration of heterogeneous ATM networks to establish end-to-end permanent virtual channels. Finally, we evaluate our agent architecture and the agent paradigm in general when applied to Network Management.     

Exact resolution of the one-machine sequencing problem with no machine idle time

This paper investigates the one-machine sequencing problem in a workshop where the machine has to satisfy the no-idle constraint, that is, the machine must process jobs without interruption. The objective is to minimize the makespan. Each job has a release date for which it is available for processing on the machine and a delivery time during which it must remain in the system after being processed by the machine. This problem has been studied without adding the no-idle constraint. It is solved in polynomial time, when the preemption of jobs is allowed, applying Jackson’s rule. But, when the preemption of jobs is not allowed, it becomes strongly NP-hard. Although, it can be solved in a very short time using Carlier’s branch and bound algorithm. Below, we propose to adapt Carlier’s branch and bound method in order to calculate an optimal nonpreemptive schedule for the problem when adding the no-idle constraint.     

Ultrastructural and histochemical analysis reveals ethylene-induced responses underlying reduced peel collapse in detached citrus fruit

Fruits from many citrus cultivars develop depressed areas in the flavedo (outer part of the peel) and albedo (inner part) following detachment. Although ultrastructural analysis may provide important information about multiple plant responses to stresses and external stimuli at the cell and tissue levels, and despite the proved efficacy of ethylene in reducing peel damage in citrus fruit, cytological responses of this horticultural crop to protective ethylene concentrations have not yet been reported. We show that applying high ethylene levels (2 μL L(-1) for 14 days) causes sublethal stress as it favored the alteration of cuticle, vacuole, middle lamella and primary wall, especially in the albedo cells, but reduced peel collapse in detached mature "Navelate" oranges (C. sinensis, L. Osbeck) held under nonstressful environmental conditions (22°C and 90-95% RH). Ethylene did not induce relevant changes in lignification but favored the deposition of pectic exudates and the release of sugars from degradation of cell polysaccharides including starch, cellulose, and pectins. In contrast, inhibiting ethylene perception by applying 1-methylcyclopropene (1-MCP) reduced these ethylene-related responses and favored degradation of cell membranes and peel damage. The overall results reflect that mature oranges tolerate high ethylene levels that might favor the activation of defense responses involving oxidative-stress related mechanisms and recycling of nutrients and carbon supply to enable cells to sustain respiration and cope with carbon deprivation stress caused by detachment.     

Maximizing the positive influence of IT for improving organizational performance

In the analysis of whether information technology (IT) has an impact on organizational performance, focus is usually placed on the relationship between an organization’s investments in IT and that organization’s performance. Therefore, it is standard to devote special attention to the size and complexity of the organization, to the investments in other organizational resources that may affect the performance of IT, and to the manner in which the two variables are measured. However, one area that has not been well explored is the manner in which the relationship between investments in IT and organizational performance develops. In this article, we show empirically that the planning and management of IT influence the organization’s endowment of resources (physical and human), which consequently has positive effects on each of the IT-related areas usually found in organizations (applications, reliable and secure systems and communications, and training and support). In turn, the functioning of these areas influences the impact of IT on the organization, which then has positive effects on organizational performance. We have used data corresponding to IT management in Spanish universities, as well as independent rankings that are useful for evaluating their performance.     

A blueprint for system-level performance modeling of software-intensive embedded systems

Exploration of design alternatives and estimation of their key performance metrics such as latency and energy consumption is essential for making the proper design decisions in the early phases of system development. Often, high-level models of the dynamic behavior of the system are used for the analysis of design alternatives. Our work presents a blueprint for building efficient and re-usable models for this purpose. It builds on the well-known Y-chart pattern in that it gives more structure for the proper modeling of interaction on shared resources that plays a prominent role in software-intensive embedded systems. We show how the blueprint can be used to model a small yet illustrative example system with the Uppaal tool, and with the Java general-purpose programming language, and reflect on their respective strengths and weaknesses. The Java-based approach has resulted in a very flexible and fast discrete-event simulator with many re-usable components. It currently is used by TNO-ESI and Océ-Technologies B.V. for early model-based performance analysis that supports the design process for professional printing systems.     

Demonstration of a technological prototype of an active‐matrix BiNem liquid‐crystal display

Abstract— The first implementation of active‐matrix addressing on a BiNem bistable nematic liquid‐crystal display has been demonstrated. Compared to previous passive‐matrix addressing, major improvements have been made for the bistable mode: a smoother image refreshment, shorter refreshing frame time compatible with that of high‐resolution e‐book displays, the use of a touch screen for interactive functions such as hand‐writing, a virtual keyboard, improved functionality for scrolling menus, partial refreshment, etc. On the same display but in the monostable mode, by using electrically controlled birefringence (ECB), the potential of displaying moving pictures at a rate of 25 images/sec, at an extended room temperature, has been demonstrated. In the ECB monostable mode, static images can be displayed down to ?20°C. A new transflective single‐polarizer optical mode has been developed to optimize the indoor and outdoor readability of the display. By lowering the surface reflection and enhancing the panel transmission, a contrast ratio of 94:1 and a transmittance of 17% have been achieved.     

A decentralized energy-based diffusion algorithm to increase the lifetime of MANETs

In this paper, we introduce a novel approach to improve overall lifetime in mobile ad hoc networks. Given the energy constraint on each node, this problem is formulated as an energy-controlled load balancing problem. Thus, our approach is quite different from usual energy-efficient routing or topology control methods. The proposed algorithm is fully distributed and ensures that each node will cooperate in proportion to its remaining energy, increasing the network lifetime. The relevance of the algorithm is evaluated through both theoretical analysis and simulations.