The pseudo-differential approach¶to finite differences revisited

We systematically derive arbitrary-order finite difference discretizations of linear (pseudo-) differential problems by appropriately approximating the symbols of the (pseudo) differential operators in frequency space. The convergence (i.e., stability and consistency) analysis of the difference schemes is based directly on micro-local properties of the exact and approximating symbols. The analytical approach presented here sheds new light on the general philosophy of finite differences. Received: November 1998 / Accepted: November 1998     

Towards SoC Validation Through Prototyping: A Systematic Approach Based on Reconfigurable Platform

Hardware/software covalidation is becoming one of the most critical issues in current System-on-Chip (SoC) design. Nowadays, covalidation is usually performed by cosimulation which is slow and lacks accuracy. The other alternative is to build a hardware prototype specific to the application. However, this alternative is expensive in terms of time, man-power, and cost. As SoCs increase in complexity, validation becomes more and more difficult, time consuming and error prone. Thus, a new approach for covalidation is inescapable. In this paper, we present a novel efficient prototyping approach for complex SoC covalidation. The proposed approach enables systematic prototyping of embedded applications on a reconfigurable platform. The process starts from the RT level model of the application. The application and the reconfigurable platform have to be adapted to obtain the prototype. We decompose the prototyping process into four steps, in order to match the application and the platform. Besides, we propose adapted solutions to deal with constraints typically encountered in existing reconfigurable platforms. The main advantages of this method are: fast and accurate validation, systematic prototyping flow, and large application field. Prototyping of a subset of VDSL using the ARM Integrator platform illustrates the effectiveness of our approach.     

Biology-based modeling to analyze uranium toxicity data on Daphnia magna in a multigeneration study

Recent studies have investigated chronic toxicity of waterborne depleted uranium on the life cycle and physiology of Daphnia magna. In particular, a reduction in food assimilation was observed. Our aims here were to examine whether this reduction could fully account for observed effects on both growth and reproduction, for three successive generations, and to investigate through microscope analyses whether this reduction resulted from direct damage to the intestinal epithelium. We analyzed data obtained by exposing Daphnia magna to uranium over three successive generations. We used energy-based models, which are both able to fit simultaneously growth and reproduction and are biologically relevant. Two possible modes of action were compared - decrease in food assimilation rate and increase in maintenance costs. In our models, effects were related either to internal concentration or to exposure concentration. The model that fitted the data best represented a decrease in food assimilation related to exposure concentration. Furthermore, observations of consequent histological damage to the intestinal epithelium, together with uranium precipitates in the epithelial cells, supported the assumption that uranium has direct effects on the digestive tract. We were able to model the data in all generations and showed that sensitivity increased from one generation to the next, in particular through a significant increase of the intensity of effect, once the threshold for appearance of effects was exceeded.     

Determination of pre-impact occupant postures and analysis of consequences on injury outcome. Part I: a driving simulator study

This paper considers pre-impact vehicle maneuvers and analyzes the resulting driver motion from their comfort seating position. Part I of this work consists of analyzing the driver behavior during a crash. The study is conducted using the LAMIH driving simulator and involves 76 participants. The emergency situation is created by a truck emerging from behind a tractor on the opposite side of the road and tearing along the participant. The driver positioning throughout the simulation is recorded via five video cameras allowing view of the front scene, the driver face, feet and pedals, hands on the steering wheel and global lateral view. Data related to braking force, seat pressure, muscular activity for major groups of muscles and actions on the steering wheel are also collected.The typical response to this type of emergency event is to brace rearward into the seat and to straighten the arms against the steering wheel, or, to swerve to attempt to avoid the impacting vehicle. While turning the steering wheel, the forearm can be directly positioned on the airbag module at time of crash which represents a potential injurious situation.These positions are used in Part II to determine scenario of positions for numerical simulation of a frontal collision.     

Single- and Multiscale Laser Patterning of 3D Printed Biomedical Titanium Alloy: Toward an Enhanced Adhesion and Early Differentiation of Human Bone Marrow Stromal Cells

This study explores the enhancement of biocompatible titanium-based implants through surface functionalization for improved bone healing. Specifically, a near-beta type Ti-13Nb-13Zr alloy is 3D printed using laser powder bed fusion and subsequently textured using nanosecond (ns) and picosecond (ps) direct laser interference patterning (DLIP) to create single-scale and multi-scale surface textures. On these textures, the cell behavior, morphology, metabolic activity and osteogenic differentiation potential of human bone marrow stromal cells are assessed using fluorescence microscopy and MTS assays. Moreover, tissue non-specific alkaline phosphatase activity served as an early osteoblast production marker. Compared to untextured specimens, both types of textures exhibited higher metabolic activity and cell proliferation. Single-scale ns-DLIP textures encouraged cell extensions anchored in groove regions, while ps-DLIP textures with hierarchical structures promoted cell extensions attaching to nanostructures on sidewalls. The groove width and nanotopographies in groove areas facilitated cell spreading. Surface topography, roughness, and surface chemistry (surface energy, wettability) influenced cell adhesion, proliferation, and differentiation. A comprehensive evaluation of DLIP-generated surface textures, including their topography and chemical states, complements the factors affecting in vitro cell behavior. Overall, this research demonstrates the potential of surface-functionalized 3Dprinted titanium for a novel generation of biocompatible implants.     

Sensor fault reconstruction and observability for unknown inputs,with an application to wastewater treatment plants

In this article, we propose a general methodology for identifying and reconstructing sensor faults on dynamical processes. This methodology is issued from the general identification theory developed in the previous papers (Busvelle, E., and Gauthier, J.-P. (2003), ‘On Determining Unknown Functions in Differential Systems, with an Application to Biological Reactor’, ESAIM: Control, Optimisation and Calculus of Variations, 9, 509–553; Busvelle, E., and Gauthier, J.-P. (2004), ‘New Results on Identifiability of Nonlinear Systems’, in 2nd Symposium on Systems, Structure and Control, Oaxaca, Mexico; Busvelle, E., and Gauthier, J.-P. (2005), ‘Observation and Identification Tools for Non Linear Systems. Application to a Fluid Catalytic Cracker’, International Journal of Control, 78, 208–234): in fact, this identification theory also provides a general framework for the problem of ‘observability with unknown inputs’. Indeed, many problems of fault detection can be formulated as such observability problems, the (eventually additive) faults being just considered as unknown inputs. Our application to ‘sensor fault detection’ for wastewater treatment plants (WWTP) constitutes an ideal academic context to apply the theory: first, in this 3-5 case (3 sensors, 5 states), the theory applies generically and, second, any system is naturally under the ‘observability canonical form’ required to apply the basic high-gain observer from Gauthier and Kupka (Gauthier, J.-P., and Kupka, I. (1994), ‘Observability and Observers for Nonlinear Systems’, SIAM Journal on Control, 32, 975–994). A simulation study on the Bleesbrük WWTP is proposed to show the effectiveness of this approach.     

Large area 15.8% n-type mc-Si screen-printed solar cell with screen printed Al-alloyed emitter

A record efficiency of 15.8% (independently confirmed at Fraunhofer ISE calibration laboratory) is reported on large area (120 cm²) n-type mc-Si rear junction Si solar cell. Minor modifications to the industrial process for p-type, such as optimization of Al-alloyed screen-printed emitter and phosphorus front surface field, led to an improvement in cell properties. Large improvement in short-circuit current of the cell was possible by decreasing the cell thickness to 130 μm.     

Capillary gas-liquid chromatographic separation of oxo and oxo-hydroxy bile acid isomers of theallo and normal series

Capillary gas-liquid chromatographic separation was studied for 60 oxo and oxo-hydroxy bile acids of theallo (5α-H, A/B-trans) and normal (5β-H, A/B-cis) series, which differ from one another in the number, position, and configuration of oxo and hydroxy groups at positions C−3, C−4, C−6, C−7, and/or C−12. Good separation of the isomers was achieved by the use of an aluminum-clad fused-silica capillary column coated with bonded and cross-linked methyl polysiloxane.     

Gastric versus duodenal feeding and gastric tonometric measurements

OBJECTIVE: To compare the influence of gastric and postpyloric enteral feeding on the gastric tonometric PCO2 gap (tonometric PCO2 - PaCO2). DESIGN: A prospective, clinical trial. SETTING: Two intensive care units in a university hospital. PATIENTS: Twenty patients undergoing mechanical ventilation and enteral feeding without catecholamines, sepsis, or sign of hypoxia. INTERVENTIONS: Patients were randomized to receive feeding through the tonometer (gastric group), or through a postpyloric tube (postpyloric group). MEASUREMENTS AND MAIN RESULTS: The patients received tube feeding at a rate of 50 mL/hr during 4 hrs. Baseline measurements included: mean arterial pressure, heart rate, tonometric parameters, arterial gases, and arterial lactate concentration. Except for lactate concentration, these measurements were repeated after 1 and 4 hrs of enteral feeding and 2 hrs after stopping enteral feeding. During the study, arterial pH and PaCO2 did not change. During enteral feeding, the PCO2 gap increased in the gastric group from a mean of 7+/-5 to 17+/-14 (SD) torr (0.9 0.7 to 2.3+/-1.9 kPa) (p< .O01) and did not change in the postpyloric group (5+/-5 to 3+/-1 torr [0.7+/-0.7 to 0.4+/-0.1 kPa]). Two hours after stopping enteral feeding, the PCO2 gap was still increased in the gastric group (15+/-9 vs. 7+/-5 torr [2.0+/-1.2 vs. 0.9+/-0.7 kPa]) (p < .01). CONCLUSION: The results indicate that gastric enteral feeding increased the PCO2 gap. However, postpyloric enteral feeding does not interact with gastric tonometric measurements and should be used when using gastric tonometry in enterally fed patients.     

Rapid progress of cirrhosis in hepatitis C: the role of age at the time of viral contamination

OBJECTIVE: The aim of this study was to assess predictive factors for the progression to liver cirrhosis in hepatitis C. METHODS: One hundred thirty six patients (79 men; 57 women; mean age 39 years) with transfusion or intravenous drug use-associated hepatitis C virus (HCV) infection were studied. Sex, cause of infection, duration of contamination, and genotype were studied as predictive factors of progression to liver cirrhosis. RESULTS: One hundred twenty three patients presented with chronic hepatitis without cirrhosis and 13 had cirrhosis. At the time of liver biopsy, rates of cirrhosis were: 0% before 40 years, 10% between 40 and 60 years, and 47% after 60 years. (p < 0.05). Rates of cirrhosis according to the age at the time of contamination were as follows: 3% before 30 years; 16% between 30 and 50 years; 46% after 50 years even though duration of the disease was comparable in the three groups. In multivariate analysis, two independent factors were associated with liver cirrhosis: age at contamination and duration of infection. CONCLUSION: Duration of infection and especially age at contamination seem better correlated with the probability of cirrhosis than the route of transmission or the genotype 1b. The results of this study suggest that progression to cirrhosis is slower in cases of contamination before 30 years of age than later on. Age at the time of contamination is an important predictive factor of progression to cirrhosis.