Mathematical Modeling of Textures: Application to Color Image Decomposition with a Projected Gradient Algorithm

In this paper, we are interested in texture modeling with functional analysis spaces. We focus on the case of color image processing, and in particular color image decomposition. The problem of image decomposition consists in splitting an original image f into two components u and v. u should contain the geometric information of the original image, while v should be made of the oscillating patterns of f, such as textures. We propose here a scheme based on a projected gradient algorithm to compute the solution of various decomposition models for color images or vector-valued images. We provide a direct convergence proof of the scheme, and we give some analysis on color texture modeling.     

Cartesian effect categories are Freyd-categories

Most often, in a categorical semantics for a programming language, the substitution of terms is expressed by composition and finite products. However this does not deal with the order of evaluation of arguments, which may have major consequences when there are side-effects. In this paper Cartesian effect categories are introduced for solving this issue, and they are compared with strong monads, Freyd-categories and Haskell’s Arrows. It is proved that a Cartesian effect category is a Freyd-category where the premonoidal structure is provided by a kind of binary product, called the sequential product. The universal property of the sequential product provides Cartesian effect categories with a powerful tool for constructions and proofs. To our knowledge, both effect categories and sequential products are new notions.     

Tuning of external-cavity semiconductor lasers with chirped diffraction gratings

We present a novel scheme of tunable semiconductor laser based on the use of a chirped grating in an external cavity. The chirped grating is fabricated using a simple holographic technique: two Gaussian beams having wavefronts with different radii of curvature are brought to interfere on a photoresist layer. The tuning properties of chirped gratings have been investigated with semiconductor lasers operated with an external cavity. With this type of grating positioned in Littrow configuration, the wavelength selection can be done by translating the grating without any need to rotate it. This cavity configuration provides a tunable output beam with an angle of propagation that is independent of the wavelength. The translation of chirped gratings was shown to tune a visible diode laser and an infrared diode laser over the same spectral band as the conventional tuning scheme where an unchirped grating is rotated.     

Characterization of furanocoumarin metabolites in parsnip webworm,Depressaria pastinacella

Although metabolites of furanocoumarins have been characterized in a wide range of organisms, to date they have been identified in only a single insect species, Papilio polyxenes. Depressaria pastinacella, the parsnip webworm, like P. polyxenes a specialist on Apiaceae, routinely consumes plant tissues higher in furanocoumarin content than does P. polyxenes and is capable of faster cytochrome P-450-mediated detoxification of these compounds. In this study, we characterized metabolites of xanthotoxin, a linear furanocoumarin, and sphondin, an angular furanocoumarin, in midguts and frass of parsnip webworms. Two metabolites were isolated and identified from webworms fed artificial diet containing xanthotoxin. LC-ESI-MS analysis resulted in the determination of a MW of 266 for the compound in the frass and one of the compounds in the midgut; ¹H NMR confirmed its structure as 6-(7-hydroxy-8-methoxycoumaryl)-hydroxyacetic acid (HCHA). The second compound from the midgut had a MW of 252 and was identified by ¹H NMR and ¹³C NMR analysis as 6-(7-hydroxy-8-methoxycoumaryl)-hydroxyethanol) (HMCH). Whereas HCHA has been found in frass of Papilio polyxenes fed xanthotoxin, HMCH has not been reported previously in insects. Although the first step of metabolism of xanthotoxin in webworms as well as P. polyxenes is likely the formation of an epoxide on the furan ring, angular furanocoumarin metabolism in webworms appears to differ. The principal metabolite of sphondin was identified as demethylated sphondin (6-hydroxy-2H-furo[2,3-h]-1-benzopyran-2-one) by LC-ESI-MS and confirmed by ¹H NMR and ¹³C NMR analyses. That webworms produce metabolites of xanthotoxin in common not only with other Lepidoptera (e.g., HCHA) but with other vertebrates (e.g., HMCH) suggests a remarkable conservatism in the metabolic capabilities of cytochrome P-450s and raises the possibility that insects may share other detoxification reactions with vertebrates with respect to toxins in foodplants.     

Effect of supplementary cementitious materials on the compressive strength and durability of short-term cured concrete

This research focuses on studying the effect different supplementary cementitious materials (silica fume, fly ash, slag, and their combinations) on strength and durability of concrete cured for a short period of time—14 days. This work primarily deals with the characteristics of these materials, including strength, durability, and resistance to wet and dry and freeze and thaw environments. Over 16 mixes were made and compared to the control mix. Each of these mixes was either differing in the percentages of the additives or was combinations of two or more additives. All specimens were moist cured for 14 days before testing or subjected to environmental exposure. The freeze-thaw and wet-dry specimens were also compared to the control mix.Results show that at 14 days of curing, the use of supplementary cementitious materials reduced both strength and freeze-thaw durability of concrete. The combination of 10% silica fume, 25% slag, and 15% fly ash produced high strength and high resistance to freeze-thaw and wet-dry exposures as compared to other mixes. This study showed that it is imperative to cure the concrete for an extended period of time, especially those with fly ash and slag, to obtain good strength and durability. Literature review on the use of different supplementary cementitious materials in concrete to enhance strength and durability was also reported.     

A comprehensive study of the liquid transfer from the front to the back of a vertical perforated sheet

Perforations contribute to liquid redistribution in corrugated sheet packings. We focus on a simplified but relevant experimental configuration where a vertical perforated flat sheet is supplied with liquid on its front side. We examine how the perforations irrigate the back of the plate. We successively consider a single perforation, a spanwise row of perforations, and a staggered array of perforations. We quantify the liquid transfer through a single row of perforations and find that the transferred flow rate per unit perforation diameter varies linearly with the supply flow rate per unit width. We also analyze the spreading of the rivulets leaking from the perforations, their merging into a continuous wavy film, and the leveling of this film as it falls down the plate. The spreading and the merging exhibit a power-law behavior in agreement with theoretical models. The leveling exhibits exponential decay behavior.     

Static and dynamic light scattering from polystyrene/cyclohexane/toluene solutions

Summary Static and dynamic light scattering data from polystyrene in cyclohexane and toluene mixed solvent are reported. It is found from the Zimm plot analysis of the static data that if the subtraction of solvent signal is made properly then, the results are consistent with those in toluene indicating a preferential adsorption of the good solvent. Contin analysis of the dynamic data yields two modes unlike the dynamics of polystyrene in single solvent solutions which exhibit a single mode at all polymer concentrations covered here. A possible interpretation of the fast and slow modes is given. Keywords: Mixed Solvent; Dilute Polymer Solution; Preferential Adsorption; Static and Dynamic Light Scattering; Relaxation Modes. Received: 28 May 1999/Accepted: 8 September 1999     

Behaviors of liver and kidney explants from chicken embryos inside plasma treated PDMS microchannels

The behavior of liver and kidney explants from chicken embryos was studied inside plasma treated rectangular PDMS (PolyDiMethylSiloxane) microchannels. We found that the plasma treatments enhance the migration of the liver and kidney cells when compared to the untreated PDMS. Liver migration was faster than kidney migration inside the microchannels. In liver cultures, cell migration resulted in the formation of a large and dense 3D tissue. After 96h of cultures, we estimated a velocity of the migration of the liver tissues inside the microchannels about 120 ± 20, 170 ± 50, 100 ± 15 μm/day respectively for the15s, 40s and 900s of plasma durations. In the case of the kidney, we estimated a velocity of migration of 50 ± 20, 50 ± 25, 100 ±50 μm/day respectively for the 15s, 40s and 900s plasma durations. In addition, we found that the migration of the embryonic cells of both organs was faster when a plasma treatment of PDMS is applied as a surface treatment when compared to our previous work using fibronectin-coated PDMS microchannels. Finally, in the case of the co-cultures on plasma treated microchannels, the liver and kidney cells migrated toward each other and merged after 5days whereas only the kidney migration was triggered in co-cultures using the fibronectin treatments. In term of liver and kidney tissue engineering, our results suggest that in vitro scaffolds filling (and cell colonisation) can be accelerated selectively a specific co-culture condition and surface treatment.     

Geochemistry of bed and suspended sediment in the Mississippi river system: provenance versus weathering and winnowing

Stream-bed sediment for the size fraction less than 150 microm, examined in 14,000 samples collected mostly from minor tributaries to the major rivers throughout the Mississippi River drainage system, is composed of 5 mineral fractions identified by factor analysis-Al-silicate minerals, quartz, calcite and dolomite, heavy minerals, and an Fe-Mn fraction. The Al-silicate fraction parallels its distribution in the regolith, emphasizing the local sediment source as a primary control to its distribution. Quartz and the heavy-mineral fraction, and associated trace elements, exhibit a complementary distribution to that of the Al-silicate fraction, with a level of enrichment in the bed sediment that is achieved through winnowing and sorting. The carbonate fraction has a distribution suggesting its dissolution during transport. Trace elements partitioned onto the Fe-Mn, possibly amorphous oxyhydride, fraction are introduced to the streams, in part, through human activity. Except for the heavy-mineral fraction, these fractions are identified in suspended sediment from the Mississippi River itself. Although comparison of the tributary bed sediment with the riverine suspended sediment is problematic, the geochemistry of the suspended sediment seems to corroborate the interpretation of the geochemistry of the bed sediment.     

The duval triangle for load tap changers, non-mineral oils and low temperature faults in transformers

Dissolved gas analysis (DGA) is widely used to detect incipient faults in oil-filled electrical equipment. IEC Standard 60599-1999 [1] and IEEE Standard C57.104-1991 [2] provide guidance for the interpretation of DGA results in service. Several diagnosis methods, such as the Rogers and Duval Triangle methods, are available to identify the different types of fault occurring in service (arcing, partial discharges, or hot spots). These methods apply to transformers filled with mineral oils, but not directly to load tap changers (LTCs) of the oil type, where normal operation involves arcing in oil, and to equipment filled with non-mineral oils (e.g., natural or synthetic esters and silicones). Also, diagnosis for low-temperature faults may be affected by the "stray gassing" of some types of oils. The present paper proposes new versions of the Duval Triangle for such cases.