Model-based approach to control over concurrency in interactive CSCW applications. Application to telemedicine

The aim of this paper is to present a model-based approach (Petri Net) to control over concurrency and solve the problem of event collision in cscw interactive software applications. Theoretical background is provided and experimental results are illustrated through telemedicine applications. From the user viewpoint, progress is achieved: the natural use of these applications is strongly enhanced and the reliability level is increased. This new approach may be applied to a large set of interactive collaborative applications as well as in the control of user interfaces. It led to an international patent application n^o pct/fr02/04472 entitled: “Management procedure for synchronous collaborative session integrated in a distributed supervisored application”.     

Two-way chromatography: Flow reversal in non-linear preparative liquid chromatography

A liquid chromatographic process is described in which the mixture to be separates and the eluant are introduced alternately at either end of the colum The products are also withdrawn alternately at either end or in side-streams. Difrerent operating schemes are shown to be possible, according as the el is more, or less strongly retained by the adsorbent than the components to be separated.Experiments are presented on the ion-exchange chromatography of Na⁺ = K⁺ mixtures with H⁺ as eluant. A theoretical analysis is given using the non-linear multicomponent equilibrium theory and performance criteria are determined. Both experiments and theory lead to the following salient fea of the process, which permit to distinguish it from existing, analytical or preparative chromatographic processes: the process is preparative: it treats large injections of highly concentrated components; the process is separative: it does not merely remove solutes from a solvant, it separates solutes from each other; the process is a binary split: it gives two products; thus multicomponent mixtures require several steps if complete separation is desired; the process is non-linear, as a result of the high concentrations used; the tailing of the peaks induced by the non-linearity is counteracted by recompression due to flow-reversal; the process reduces dilution and saves eluant: one of the components may be collected highly concentrated, even pure, avoiding thus secondary separation; the process requires slightly more adsorbent capacity than conven chromatography, for the same production; the process works best when the eluant is more, or less strongly retained than the components to be separated, but not intermediately; the process uses intermediate storage of part of the effluents, and their “reflux” in subsequent steps.     

Tissue culture assays using Caco-2 cell line differentiate virulent from non-virulent Listeria monocytogenes strains

OBJECTIVE: Fibroblast growth factor 9 (FGF-9) is a relatively new member of the FGF family isolated from the conditioned medium of a human glioblastoma cell line as a secreting type factor that exhibits a growth-stimulating effect on primary glial cells. To elucidate the roles of FGF-9 in human brain tumors, the expression and biological activities of FGF-9 were studied using culture cells and surgically obtained tumor specimens. METHODS: Measurement of FGF-9 and basic FGF in conditioned media of cell cultures was performed by using a sandwich enzyme immunoassay. The mitogenic effect of FGF-9 was evaluated by cell growth studies. FGF-9 expression in vivo was demonstrated by immunohistochemistry. RESULTS: One of 4 glioma cell lines and 4 of 16 human meningiomas examined actually secreted detectable amounts of FGF-9 proteins. In comparison, basic FGF production was detected from 3 of 4 glioma cell lines and 11 of 16 human meningiomas. Similarly to basic FGF, recombinant human FGF-9 significantly stimulated the in vitro cell proliferation in three of four glioma cell lines investigated in a dose-dependent manner. A time course growth study using U87 MG cells revealed an accelerated growth stimulation by FGF-9 after Day 4. The growth stimulatory activity was also shown in three of four human meningiomas studied. Moderate to strong immunoreactivity for FGF-9 was observed in 40 (82%) of 49 human brain tumors examined irrespective of origin, tumor type, grade of malignancy, or whether initial or recurrent. In contrast, strong immunostaining was localized in neurons in the normal human cerebral cortex. CONCLUSION: The present findings suggest that FGF-9 may be involved in the biology of human brain tumors with a possible importance in tumor cell growth. Whether the growth factor is more generally involved in oncogenesis of human tumors awaits further investigation.     

Reversibility and performances in productive chromatography

Irreversibilities in industrial chromatographic processes imply dissipation of free enthalpy in the form of dilution of the products by the eluent. It is shown that an important source of entropy is related to the propagation in the column of sharp concentration fronts of large amplitude (shocks).Some unconventional chromatographic modes are presented (two-way chromatography, segmented recycle chromatography) which reduce this particular source of entropy, and thus reduce the eluent consumption required to reach a given product purity. The performances of these modes are compared with those of the two conventional operating modes (classical single-pass chromatography, and chromatography with intermediate cut and recycle). The analysis is illustrated by experiments on the separation of K⁺ and Na⁺ cations with H⁺ as eluent on a sulfonic ionic exchanger bed.     

Blind separation of piecewise stationary non-Gaussian sources

We address independent component analysis (ICA) of piecewise stationary and non-Gaussian signals and propose a novel ICA algorithm called Block EFICA that is based on this generalized model of signals. The method is a further extension of the popular non-Gaussianity-based FastICA algorithm and of its recently optimized variant called EFICA. In contrast to these methods, Block EFICA is developed to effectively exploit varying distribution of signals, thus, also their varying variance in time (nonstationarity) or, more precisely, in time-intervals (piecewise stationarity). In theory, the accuracy of the method asymptotically approaches Cramér–Rao lower bound (CRLB) under common assumptions when variance of the signals is constant. On the other hand, the performance is practically close to the CRLB even when variance of the signals is changing. This is demonstrated by comparing our algorithm with various methods that are asymptotically efficient within ICA models based either on the non-Gaussianity or the nonstationarity. The benefit of our algorithm is demonstrated by examples with real-world audio signals.     

Synthesis, Crystal Structure and Interaction With DNA of N,N'-(Butane-1,4-Diyl)Bis(Guanidinium) Tetrachloroplatinate (II)

The design, synthesis, crystal structure and interaction with DNA of the N,N'-(butane-1,4-diyl)bis(guanidinium) tetrachloroplatinate(ll) are described. Crystal data: a = 8.152(1), b = 8.889(4), c = 10.700(3) A , alpha = 81.59(3), beta = 87.99(5), gamma = 78.48(6) degrees , V = 752(1) A(3), Z = 2 , space group P-1. The structure was refined to R = 0.039 and Rw = 0.046 from 1853 reflections (I > 3sigma(I)). This compound, named PtC(4)Gua, does not exhibit a center of symmetry and the center linker chain C(2) - C(3) - C(4) - C(5) is in gauche conformation. The cation is bisprotonated with the H(+) attached to the imine group of each terminal guanidinium function. The presence of the platinum moiety reinforces the binding of the butane(bis)guanidinium structure with double stranded DNA as judged from thermal denaturation studies and DNA unwinding experiments.     

Anthropogenic aerosol emissions mapping and characterization by imaging spectroscopy – application to a metallurgical industry and a petrochemical complex

This paper is focused on the retrieval of industrial aerosol optical thickness (AOT) and microphysical properties by means of airborne imaging spectroscopy. Industrial emissions generally lead to optically thin plumes requiring an adapted detection method taking into account the weak proportion of particles sought in the atmosphere. To this end, a semi-analytical model combined with the Cluster-Tuned Matched Filter (CTMF) algorithm is presented to characterize those plumes, requiring the knowledge of the soil under the plume. The model allows the direct computation of the at-sensor radiance when a plume is included in the radiative transfer. When applied to industrial aerosol classes as defined in this paper, simulated spectral radiances can be compared to ‘real’ MODTRAN (Moderate Resolution Atmospheric Transmission) radiances using the Spectral Angle Mapper (SAM). On the range from 0.4 to 0.7 µm, for three grounds (water, vegetation, and bright one), SAM scores are lower than 0.043 in the worst case (a both absorbing and scattering particle over a bright ground), and usually lower than 0.025. The darker the ground reflectance is, the more accurate the results are (typically for reflectance lower than 0.3). Concerning AOT retrieval capabilities, with a pre-calculated model for a reference optical thickness of 0.25, we are able to retrieve plume AOT at 550 nm in the range 0.0 to 0.4 with an error usually ranging between 9% and 13%. The first test case is a CASI (Compact Airborne Spectrographic Imager) image acquired over the metallurgical industry of Fos-sur-Mer (France). First results of the use of the model coupled with CTMF algorithm reveal a scattering aerosol plume with particle sizes increasing with the distance from the stack (from detection score of 54% near the stack for particles with a diameter of 0.1 µm, to 69% away from it for 1.0 µm particles). A refinement is made then to estimate more precisely aerosol plume properties, using a multimodal distribution based on the previous results. It leads to find a mixture of sulfate and brown carbon particles with a plume AOT ranging between 0.2 and 0.5. The second test case is an AHS (Airborne Hyperspectral Scanner) image acquired over the petrochemical site of Antwerp (Belgium). The first CTMF application results in detecting a brown carbon aerosol of 0.1 µm mode (detection score is 51%). Refined results show the evolution of the AOT decreasing from 0.15 to 0.05 along the plume for a mixture of brown carbon fine mode and 0.3 µm radius of sulfate aerosol.     

Experimental and numerical study of granular medium-rough wall interface friction

Wall roughness plays a crucial role in granular medium - rough wall interface friction. In this study, an experimental device has been designed to study the influence of boundary conditions, more specifically wall roughness, on the behavior of sheared granular medium. The study is based on use of an analog model, and consists of simulating roughness by means of notches and grains in the medium by monodisperse beads and on use of a numerical model based on the discrete element method. The test protocol entails displacing at fixed speed notched rods under confined granular medium. Movement of the beads layer near the rods as well as friction of the beads against the rods are both studied herein. Results indicate that the parameter controlling friction at the granular medium - rough wall interface is primarily the depth of beads embedment in surface asperities. The objective of the associated numerical modeling is to supplement the experimental results.     

Golden-ratio as a substitute to geometric and harmonic counting to determine multi-author publication credit

Countless bibliometric indexes have been proposed to assess researchers’ productivities, in particular, in fields where the author sequence is regarded helpful in determining authors’ individual credits. Unfortunately, the most popular h-index ignores author ranks and leads to bias with multi-author publications; and of the many bibliometric counting methods proposed for assigning credit to authors, such as harmonic or geometric counting, none seems to have been widely adopted yet. In this work, I challenge the assumption that the total credit for a publication be equal to 1. This total-credit normalization assumption diminishes first-author credit and may impede adoption of multi-author-aware credit assignment rules. Other than on relative contributions, author credit could be based on variables such as accountability, which remains unchanged for the first (and potentially, the last) author regardless of additional coauthors. Therefore, I study the adequacy of several counting methods for first-author-normalized credit, giving full credit to the first author while also crediting coauthors. Harmonic counting has been shown to agree well with empirical data; however, unlike geometric counting, harmonic counting results in unbounded total credit for a publication with first-author-credit normalization in the limit of many authors. I therefore propose adaptable geometric counting and evaluate how it combines the advantages of harmonic and geometric counting through an additional parameter. I show that the golden ratio is a parameter for geometric counting that agrees as well as harmonic counting with empirical data for total-credit normalization; and I discuss the impact of using adaptable geometric counting with first-author-normalized credit. In particular, the latter features bounded total credits even when full credit is given to first authors. In conclusion, geometric counting with the golden ratio can be used for credit assignment without having to choose a parameter value, yet offers customization potential and can be combined with either normalization assumption.