Probabilistic linear models for multiresolution estimation in gray-level images

A multiresolution analysis of digital gray-level images is presented. A gray-level multi-scale framework is determined from two main assumptions: the gray scale is binary at the finest spatial resolution, and the gray levels of composed regions are obtained additively. In order to interrelate the gray-level histograms of the same image at different resolutions, probabilistic linear models are developed, which are then applied for estimation. Linear-optimization theory is used as a way of constructing such models. A general procedure for image processing is sketched, based on gray-level estimation. A versatile algorithm for nonlinear filtering is derived. Some examples of prospective applications are given.This work was partially supported by grant TIC91-646 from the DGYCIT of the Spanish Government.     

A genetic model for undifferentiated cell tumor formation: similar tumors formed by different cell lines transformed by the E1A oncogene

The activation of oncogenes and the mutation/deletion of suppressor genes may be involved in tumor heterogeneity. In an attempt to study tumor heterogeneity, we transformed cell lines from epithelial (PAM 212), mesenchymal (NIH-3T3), or melanocytic origin (L-BIOBR) with the wild type E1a oncogene. To make the cell lines tumorigenic, cells were infected with Harvey sarcoma virus carrying the v-H-ras oncogene. The transformed cells were injected into nude mice and the tumors studied by optical and electron microscopy. The tumors formed by v-H-ras-transformed cells consisted of epitheliod melanomas, spindle cells sarcomas and poorly-differentiated carcinomas, depending on the cell of origin. In contrast, the tumors obtained from cells also carrying the E1a oncogene showed a predominant small and undifferentiated cell pattern regardless of the cell of origin. We conclude that the E1a oncogene products induce a negative control of differentiation, independent of the cell type, and that tumors formed by cells carrying the E1a oncogene display an undifferentiated cell pattern.     

Effect of microwave heating on quality and mycoflora of sorghum grain

Sorghum (cv. Maldandi M35-1) was modified to 12, 14 and 16% moisture content (m.c.) and heat-treated with microwave energy at 3 levels, for 30 sec (=4.5, 9 and 18 kJ), and 60 sec (=9, 18 and 36 kJ). The effect of microwave heating on rise and subsequent fall in grain temperature, reduction in m.c. and quality characteristics including germination, seedling dry matter, free fatty acids (FFA) and contaminant fungi was determined. The temperature attained and the moisture loss in the sorghum grain was affected by grain m.c. and the time of exposure. At the lowest and highest microwave treatment level grain temperatures reached 30–40°C and 90–101°C, respectively. However, a 60-sec treatment at the highest energy level was lethal for the grain, particularly at 14 and 16% m.c. The FFA values were unaffected by microwave treatment. Statistical analyses showed that the microwave power level and time individually, and power level × time interactions were significant for most quality characteristics. The fungi present most abundantly on the sorghum grain were Eurotium spp., Aspergillus candidus, A. niger and Penicillium spp. Increasing m.c. and microwave heating resulted in elimination of most fungi after a 30-sec exposure time. With a 60-sec exposure period, practically all fungi were eliminated from the grain.     

Cyclic variations in the permeability of the cell wall of Saccharomyces cerevisiae.

To study cell-cycle-related variations in wall permeability of Saccharomyces cerevisiae, two approaches were used. First, an asynchronous culture was fractionated by centrifugal elutriation into subpopulations containing cells of increasing size. The subpopulations represented different stages of the cell cycle as judged by light microscopy. Cell wall porosity increased when these subpopulations became enriched with budded cells. Secondly, synchronous cultures were obtained by releasing MATa cells from alpha-factor induced G1-arrest. These cultures grew synchronously for at least two generations. The cell wall porosity increased sharply in these cultures, shortly before buds became visible and was maximal during the initial stages of bud growth. It decreased in cells which had completed nuclear migration and before abscission of the bud had occurred. The porosity reached its lowest value during abscission and in unbudded cells. We examined the incorporation of mannoproteins into the wall during the cell cycle. SDS-extractable mannoproteins were incorporated continuously. However, the incorporation of glucanase-extractable mannoproteins, which are known to affect cell wall porosity, showed cyclic oscillations and reached its maximum after nuclear migration. This coincided with a rapid decrease in cell wall porosity, indicating that glucanase-extractable mannoproteins might contribute to this decrease.     

Process-based cost modeling of photonics manufacture: the cost competitiveness of monolithic integration of a 1550-nm DFB laser and an electroabsorptive modulator on an InP platform

The monolithic integration of components holds promise to increase network functionality and reduce packaging expense. Integration also drives down yield due to manufacturing complexity and the compounding of failures across devices. Consensus is lacking on the economically preferred extent of integration. Previous studies on the cost feasibility of integration have used high-level estimation methods. This study instead focuses on accurate-to-industry detail, basing a process-based cost model of device manufacture on data collected from 20 firms across the optoelectronics supply chain. The model presented allows for the definition of process organization, including testing, as well as processing conditions, operational characteristics, and level of automation at each step. This study focuses on the cost implications of integration of a 1550-nm DFB laser with an electroabsorptive modulator on an InP platform. Results show the monolithically integrated design to be more cost competitive over discrete component options regardless of production scale. Dominant cost drivers are packaging, testing, and assembly. Leveraging the technical detail underlying model projections, component alignment, bonding, and metal-organic chemical vapor deposition (MOCVD) are identified as processes where technical improvements are most critical to lowering costs. Such results should encourage exploration of the cost advantages of further integration and focus cost-driven technology development.     

Radiation effects in a model ceramic for nuclear waste disposal

The safe immobilization of nuclear waste in geological repositories is one of the major scientific challenges facing humanity today. Crystalline ceramics hold the promise of locking up actinides from nuclear fuel and excess weapons plutonium in their structure thereby isolating them from the environment. This paper presents the atomistic details of radiation damage in a model ceramic, zircon.     

Confidence voting method ensemble applied to off-line signature verification

In this paper, a new approximation to off-line signature verification is proposed based on two-class classifiers using an expert decisions ensemble. Different methods to extract sets of local and a global features from the target sample are detailed. Also a normalization by confidence voting method is used in order to decrease the final equal error rate (EER). Each set of features is processed by a single expert, and on the other approach proposed, the decisions of the individual classifiers are combined using weighted votes. Experimental results are given using a subcorpus of the large MCYT signature database for random and skilled forgeries. The results show that the weighted combination outperforms the individual classifiers significantly. The best EER obtained were 6.3 % in the case of skilled forgeries and 2.31 % in the case of random forgeries.     

IR and Raman studies and effect of γ radiation on crystallization of some lead borate glasses containing Al2O3

IR and Raman spectra of glass ceramics based on PbO-Cr₂O₃-B₂O₃glass composition system have been studied. The bands characteristic of BO₃. and BO₄ functional groups are present in all the samples. An incorporation of Al₂O₃(up to 5 mol%) in the initial glass composition considerably changes the glass network structure and relative concentrations of BO₃ and BO₄ groups. The composition 50 PbO-20 Cr₂O₃-25 B₂O₃-5 Al₂O₃(in mol%) reveals a maximum fraction of boron in the BO₄ group. A sample of this composition heat treated at 850° C for 25 h shows a maximum crystallization fraction with Pb₂O · CrO₄ as a prominent crystalline phase. The glasses irradiated with rays inhibit the crystallization into the Pb₂O · CrO₄ phase. They also show relatively smaller thermal conductivity.