Low Temperature Hydrolysis of Carbonyl Sulfide Using γ-Alumina Catalysts

The hydrolysis of COS using alumina as catalyst in the temperature range 10–80°C is described in detail. The rate of COS hydrolysis is found to be approximately first order in [COS] but is significantly inhibited with increasing [H₂O]. Addition of CO₂ is also found to have an inhibiting effect on the rate of hydrolysis, but no marked effect is observed when additional H₂S is present in the feedstock. The reaction in this temperature range is contrasted with the previous studies at higher temperatures and it is suggested that the reaction proceeds via reaction of adsorbed COS with surface hydroxyl groups on the alumina. Supporting evidence for this is provided from experiments in which water was not co-fed with COS, or the flow of water vapour was interrupted. In both cases, an initial increase in the rate of COS hydrolysis is observed. The rate of COS hydrolysis can be significantly enhanced by the addition of Fe, Co, Ni, Cu and Zn to the alumina.     

Instantaneous envelope and phase extraction from real signals: Theory,implementation, and an application to EEG analysis

This paper presents a unified treatment of various important signal processing techniques for the extraction of the instantaneous envelope and phase of a real signal. These techniques include Complex Demodulation, Hilbert Transformation, In-Phase and In-Quadrature Filtering, Phase-Locked Loop Demodulation, and Peak Amplitude and Zero-Crossing Detection. The salient points in the mathematical theory and implementation of these techniques are outlined, as well as their interrelationships via the theory of analytic signals. The advantages and limitations of each of these techniques are elaborated upon, and Complex Demodulation is shown to be the most effective and flexible method from an implementation point of view. The relation of the above techniques to Fourier spectrum analysis is elucidated, and an example is presented of applying Complex Demodulation for the quantification of time nonstationarities in the electrographic morphology of an EEG waveform.     

Development of the agar-disc method for the rapid screening of strains with increased productivity

A simple model of colony growth and product accumulation in an agar disc was developed assuming constant rate of increase of colony biomass and a maturation- decay behaviour of the specific productivity of the biomass. Experimental data obtained with three erythromycin-producing strains of Streptomyces erythreus followed the predicted behaviour of the apparent specific productivity of the colony. The latter parameter exhibited a good correlation with the specific rate of product formation observed in liquid culture. A more sensitive correlation, and higher specific productivities, were obtained with agar discs made of a fermentation-type medium than with a maintenance-type medium. Estimation of the colony biomass through its surface area proved to be satisfactory in the conditions adopted, though it represents a major potential source of error.     

Some statistical properties of the minimum spanning forest

A minimum spanning forest method is described which finds cluster patterns in a random graph of points. A relation between the main number of clusters and a defined fixed thresholding value is obtained. Then, using the number of clusters as a parameter, a uniformity test suitable for low statistics data sets is proposed. Finally, some effective applications on simulated and real data are also discussed.     

Interferometric analysis of reorientational nonlinear phenomena at 10.6 microm in a nematic liquid crystal

We describe an infrared interferometric technique based on a two-dimensional spatial fringe analysis Fourier method for investigating the characteristic ring diffraction pattern generated by the self-phase-modulation effect induced in nematic liquid crystals (NLCs) by an infrared laser beam and for measuring the nonlinear refractive index of the NLCs. The experimental setup employs a Mach-Zehnder interferometer with a cw CO2 laser emitting at 10.6 microm and a pyroelectric optoelectronic sensor matrix to detect the modulated ring-pattern intensity distribution formed in the far field by a nematic E7 sample. A Fourier-transform-based analysis of the interference fringe pattern allows comparison of the measurements with the theoretical ring-pattern intensity distribution. We show that accurate determination of the nonlinear refractive index can be obtained by analyzing the two-dimensional phase distribution of the modulated ring pattern.     

Improving volcanic ash cloud detection by a robust satellite technique

Automated and reliable satellite-based techniques are strongly required for volcanic ash cloud detection and tracking. In fact, volcanic ash clouds pose a serious hazard for air traffic and the synoptic (and possibly frequent) coverage offered by satellites can provide exciting opportunities for monitoring activities as well as for risk mitigation purposes.A new, AVHRR-based technique for improved automatic detection of volcanic clouds by means of multi-temporal analysis of historical, long-term satellite records has been recently proposed. The technique basically rests on the Robust AVHRR Techniques (RAT) approach, which is an innovative strategy of satellite data analysis, devoted to a former characterisation of the measured signal, in terms of expected value and natural variability and a further recognition of signal anomalies by an automatic, unsupervised change detection step. In this work, an extension of this method to nighttime observations is presented, by using thermal infrared information coming from AVHRR bands centred approximately at 3.5, 11.0 and 12.0 μm. Results achieved for two recent eruptive events of Mount Etna (occurred in May 2000 and in July 2001) seem to be encouraging, showing clear improvements in terms of ash detection sensitivity as well as in terms of false alarms reduction. The technique performance is also evaluated by comparison with the traditional “split-window” brightness temperature difference method; this exercise revealed a general improvement obtained by the proposed approach, even though some common problems still remain unsolved. The main merits of such an approach are its intrinsic self-adaptability to different environmental/natural/observational conditions and its natural exportability also to different satellite sensors. The results here presented show the benefits of such a technique especially when different observational conditions (time of pass, seasonal period, atmospheric moisture, solar illumination, volcanic cloud composition, satellite angles of view, etc.) are considered.The future prospects, also in terms of possible operational scenarios, coming from the implementation of such an approach on the new generation of satellite sensors (like, for example, SEVIRI aboard Meteosat Second Generation platform) are also discussed.     

Virial Coefficients from Burnett Measurements for the R116 + CO<Subscript>2</Subscript> System

PVTx measurements for the R116 + CO₂ system for four isotherms (283, 304, 325 and 346 K) were performed. In total, 16 runs were performed in a pressure range from 5100 to 140 kPa. Seven runs along four isotherms in a pressure range from 3400 to 280 kPa were performed for pure hexafluoroethane (R116), and the second and third virial coefficients were derived. The values of the virial coefficients for CO₂ were adopted from our previous measurements. The second and third virial coefficients along with the second and third cross-virial coefficients were derived from the mixture results. The Burnett apparatus was calibrated using helium. The experimental uncertainty in second and third virial coefficients was estimated to be within ±2 cm³· mol^–1 and ±500 cm⁶ ·mol ^–2, respectively.     

Functional repertoire of dendritic cells generated in granulocyte macrophage-colony stimulating factor and interferon-alpha

Monocyte-derived dendritic cells (DCs) generated in granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin-4 (IL-4-DCs) are used to enhance antitumor immunity in cancer patients, although recent evidence suggests that their functional repertoire may be incomplete; in particular, IL-4-DCs appear unable to induce type 2 cytokine-producing T helper (Th) cells. To assess whether type 1 interferon (IFN) could replace IL-4 and generate DCs with a more complete repertoire, we characterized in detail DCs generated from human monocytes cultured with GM-CSF and IFN-alpha (IFN-DCs). We found that IFN-alpha induces DC differentiation more efficiently than IL-4, yielding similar numbers of DCs in a shorter time and that this differentiation persists upon removal of cytokines. Although IFN-DCs had a more mature immunophenotype than IL-4-DCs, showing higher expression of CD80, CD86, and CD83, they still preserved comparable endocytic and phagocytic capacities and responsiveness to maturation stimuli. IFN-DCs had strong antigen-presenting capacity, inducing intense proliferation of T cells to alloantigens or influenza virus. Moreover, IFN-DCs produced lower levels of IL-12p70 and higher levels of IFN-alpha, IL-4, and IL-10 than IL-4-DCs. As a consequence of this different pattern of cytokine secretion, IFN-DCs induced T cells to produce type 1 (IFN-gamma) and type 2 (IL-4 and IL-10) cytokines, and as expected, IL-4-DCs induced only Th1 differentiation. As immune responses with extreme Th1 bias are considered inadequate for the induction of optimal, systemic antitumor immunity, the ability of IFN-DCs to promote more balanced cytokine responses may suggest the advisability to consider these cells in the development of future, DC-based immunotherapy trials.     

Relation Between Naming and Literacy in Children With Word-Finding Difficulties.

Difficulties with picture naming tasks are associated with literacy problems. When given naming tasks, children with dyslexia are slower to produce words and have a higher proportion of errors (M. Wolf & P. G. Bowers, 1999). However, little is known about the relation between literacy and naming in other populations. This study investigated this relation in 20 children (age 6 years 6 months to 7 years 11 months) with word-finding difficulties. The children in the sample performed very poorly on assessments of naming, but unlike children with dyslexia, they were found to have decoding and spelling abilities within the normal range. In addition, their abilities on phonological awareness tasks were at a similar level to their decoding abilities. In contrast, their performance on reading comprehension and language comprehension measures was significantly worse than their performance on decoding, spelling, and rhyme awareness measures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A memory-based approach to sensory-motor coordination

In this work a visual-based autonomous system capable of memorizing and recalling sensory-motor associations is presented. The robot's behaviors are based on learned associations between its sensory inputs and its motor actions. Perception is divided into two stages. The first one is functional: algorithmic procedures extract in real time visual features such as disparity and local orientation from the input images. The second stage is mnemonic: the features produced by the different functional areas are integrated with motor information and memorized or recalled. An efficient memory organization and fast information retrieval enables the robot to learn to navigate and to avoid obstacles without need of an internal metric reconstruction of the external environment. Received: 22 November 1996 / Accepted: 18 November 1997