Neointimal formation by circulating bone marrow cells

The origin of smooth muscle cells involved in vascular healing was examined. Eighteen C57BL/6 (Ly 5.2) female mice underwent whole body irradiation followed by transfusion with 10(6) bone nucleated marrow cells from congenic (Ly 5.1) male donors. Successful repopulation by donor marrow was demonstrated after 4 weeks by flow cytometry with FITC-conjugated A20.1/Ly 5.1 monoclonal antibody. The iliac artery of six of the chimeric mice was scratch-injured by five passes of a probe, causing severe medial damage. After 4 weeks the arterial lumen was obliterated by a cell-rich neointima, with alpha-smooth muscle actin-containing cells present around the residual lumen. Approximately half of these cells were of male donor origin, as evidenced by in situ hybridization with a Y chromosome-specific probe. An organized arterial thrombus was formed in the remaining 12 chimeric mice by inserting an 8.0 silk suture into the left common carotid artery. Donor cells staining with alpha-smooth muscle actin were found in those arteries sustaining serious damage but not in arteries with minimal damage. Our results suggest that bone marrow-derived cells are recruited in vascular healing as a complementary source of smooth muscle-like cells when the media is severely damaged and few resident smooth muscle cells are available to effect repair.

Halo formation in directional solidification

A new model of halo formation in directional solidification is presented. The model describes halo formation in terms of competitive growth between the halo phase and coupled eutectic in liquid with a nominal composition that follows the primary phase liquidus extension with decreasing temperature. The model distinguishes between the effects of constitutional, capillarity and (where applicable) kinetic undercooling and avoids a number of theoretical inconsistencies associated with previous models. The critical growth rate for halo formation in directionally solidified hypereutectic Al-Si alloys is calculated using the model in conjunction with models of primary phase and coupled eutectic growth from the literature. The calculated result agrees reasonably well with the experimental result of Yilmaz and Elliott (Met. Sci. 18 (1984) 362), given the use of a relatively simple isolated dendrite tip model to calculate the growth undercooling of the halo tip. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

Indirect certainty equivalents for the firm facing price and production uncertainty

Producer decisionmaking under uncertainty is characterized using indirect objective functions. The characterization is for the class of producers with continuous and nondecreasing preferences over stochastic incomes who face both price and production uncertainty. (C) 2002 Elsevier Science B.V. All rights reserved.

Price dispersion and price indexes

The traditional theory of price index numbers is based on the law of one price. But in the real world, we frequently observe the existence of an equilibrium price dispersion instead of one price of equilibrium. This article discusses the effects of price dispersion on two price indexes: the cost of living index and the consumer price index. With price dispersion and consumer searching for the lowest price, these indexes cannot be interpreted as deterministic indicators, but as stochastic indicators, and they can be biased if price dispersion is not taken into account. A measure for the bias of the consumer price index is proposed and the article ends with an estimation of the bias based on data obtained from the consumer price index calculated for the city of Sao Paulo, Brazil, from January 1988 through December 2004. The period analysed is very interesting, because it exhibits different inflationary environments: high levels and high volatility of the rates of inflation with great price dispersion until July 1994 and low and relatively stable rates of inflation with prices less dispersed after August 1994.

A comparative study of similarity measures for manufacturing cell formation

We introduced a spectral clustering algorithm based on the bipartite graph model for the Manufacturing Cell Formation problem in [Oliveira S, Ribeiro JFF, Seok SC. A spectral clustering algorithm for manufacturing cell formation. Computers and Industrial Engineering. 2007 [submitted for publication]]. It constructs two similarity matrices; one for parts and one for machines. The algorithm executes a spectral clustering algorithm on each separately to find families of parts and cells of machines. The similarity measure in the approach utilized limited information between parts and between machines. This paper reviews several well-known similarity measures which have been used for Group Technology. Computational clustering results are compared by various performance measures. (C) 2008 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.

A spectral clustering algorithm for manufacturing cell formation

A graph clustering algorithm constructs groups of closely related parts and machines separately. After they are matched for the least intercell moves, a refining process runs on the initial cell formation to decrease the number of intercell moves. A simple modification of this main approach can deal with some practical constraints, such as the popular constraint of bounding the maximum number of machines in a cell. Our approach makes a big improvement in the computational time. More importantly, improvement is seen in the number of intercell moves when the computational results were compared with best known solutions from the literature. (C) 2009 Elsevier Ltd. All rights reserved.

Flex cars and the alcohol price

We build a model that incorporates the effect of the innovative ""flex"" car, an automobile that is able to run with either gasoline or alcohol, on the dynamics of fuel prices in Brazil. Our model shows that differences regarding fuel prices will now depend on the proportions of alcohol, gasoline and flex cars in the total stock. Conversely, the demand for each type of car will also depend on the expected future prices of alcohol and gasoline (in addition to the car prices). The model reflects our findings that energy prices are tied in the long run and that causality runs stronger from gasoline to alcohol. The estimated error correction parameter is stable, implying that the speed of adjustment towards equilibrium remains unchanged. The latter result is probably due to a still small fraction of flex cars in the total stock (approx. 5%), despite the fact that its sales nearly reached 100% in 2006. (C) 2009 Elsevier B.V. All rights reserved.

Multicusped crocodyliform teeth from the Upper Cretaceous (Sao Jose do Rio Preto Formation, Bauru Group) of Sao Paulo, Brazil

The six peculiar multicusped teeth described here were collected from sediments of the Upper Cretaceous of Sao Jose do Rio Preto Formation, near Ibira (northeastern Sao Paulo, Brazil). Their bulbous crowns are slightly labio-lingual compressed, and bear a main plus two accessory cusps, which conceal a well developed cingulum. Wear facets are seen on the main and distal accessory cusps. Comparison to the known Crocodyliformes with multicusped teeth show that the new material is not referable to ""protosuchians"" or eusuchians, nor related to two unnamed forms from Morocco and ""notosuchians"" such as Uruguaysuchus, Chiamaerasuchus, and Simosuchus. On the other hand, possible affinities with Candidodon and Malawisuchus were maintained based on shared traits. This includes teeth with the main cusp and some accessory cusps arranged in more than one axis, a previously defined unambiguous apomorphy of the putative clade composed of Candidodon plus Malawisuchus. The term Candidodontidae can be applied to this group, and defined as all taxa closer to Candidodon itapecuruensis than to Notosuchus terrestris, Uruguaysuchus aznarezi, Comahuesuchus brachybuccalis, Sphagesaurus huenei, Baurusuchus pachecoi, and Crocodylus niloticus. (C) 2009 Elsevier Ltd. All rights reserved.

Auction price anomalies: Evidence from wool auctions in Australia

Using detailed Australian wool auction data we test for further evidence of pricing anomalies at sequential auctions. We find that an anomaly frequently exists and order is frequently endogenously determined. Moreover, prices increase through some sales and decrease through others. We examine whether it is possible to explain the variation in the anomaly across sales and conclude that there is no systematic relationship between the direction of the price anomaly and the characteristics of the wool or the auction. We do, however, find evidence that an anomaly, is more likely in longer sales.

Modification-related porosity formation in hypoeutectic aluminum-silicon alloys

A series of aluminum-10 wt pet silicon castings were produced in sand molds to investigate the effect of modification on porosity formation. Modification with individual additions of either strontium or sodium resulted in a statistically significant increase in the level of porosity compared to unmodified castings. The increase in porosity with modification is due to the presence of numerous dispersed pores, which were absent in the unmodified casting. It is proposed that these pores form as a result of differences in size of the aluminum-silicon eutectic grains between unmodified and modified alloys. A geometric model is developed to show how the size of eutectic grains can influence the amount and distribution of porosity. Unlike traditional feeding-based models, which incorporate the effect: of microstructure on permeability, this model considers what happens when liquid is isolated from the riser and can no longer flow. This simple isolation model complements rather than contradicts existing theories on modification-related porosity formation and should be considered in the development of future comprehensive models.

Evaluation of the enthalpy of formation, proton affinity, and gas-phase basicity of gamma-butyrolactone and 2-pyrrolidinone by isodesmic reactions

The knowledge of thermochemical parameters such as the enthalpy of formation, gas-phase basicity, and proton affinity may be the key to understanding molecular reactivity. The obtention of these thermochemical parameters by theoretical chemical models may be advantageous when experimental measurements are difficult to accomplish. The development of ab initio composite models represents a major advance in the obtention of these thermochemical parameters,. but these methods do not always lead to accurate values. Aiming at achieving a comparison between the ab initio models and the hybrid models based on the density functional theory (DFT), we have studied gamma-butyrolactone and 2-pyrrolidinone with a goal of obtaining high-quality thermochemical parameters using the composite chemical models G2, G2MP2, MP2, G3, CBS-Q, CBS-4, and CBS-QB3; the DFT methods B3LYP, B3P86, PW91PW91, mPW1PW, and B98; and the basis sets 6-31G(d), 6-31+G(d), 6-31G(d,p), 6-31+G(d,p), 6-31++G(d,p), 6-311G(d), 6-311+G(d), 6-311G(d,p), 6-311+G(d,p), 6-311++G(d,p), aug-cc-pVDZ, and aug-cc-pVTZ. Values obtained for the enthalpies of formation, proton affinity, and gas-phase basicity of the two target molecules were compared to the experimental data reported in the literature. The best results were achieved with the use of DFT models, and the B3LYP method led to the most accurate data.

Reserve price commitments in auctions

It is well known that the optimal auction-one that maximizes the seller's expected revenue-can be implemented using a standard auction format with a suitably chosen reserve price. This reserve price is above the seller's value of retaining the object and the mechanism requires a commitment not to sell the object below the reserve. This commitment is what makes the reserve valuable to the seller. However, in practice, a reserve price commits the seller to sell the object if the reserve is reached, but does not commit her to withhold the object from sale if bidding falls short of the reserve. In this note we investigate whether reserve prices remain valuable for the seller when she may negotiate with the highest bidder if the reserve is not met. We show that the value of the reserve price may be completely undermined if the seller is a sufficiently weak bargainer. (c) 2004 Elsevier B.V. All rights reserved.

Electrochemical degradation of glyphosate formulations at DSA(A (R)) anodes in chloride medium: an AOX formation study

The electrochemical degradation of different glyphosate herbicide formulations on RuO(2) and IrO(2) DSA(A (R)) electrodes is investigated. Parameters that could influence the formation of organochloride compounds during electrolysis are studied. The effects of chloride concentration, electrodic composition, current density, and electrolysis time are reported. The influence of the oxide composition on herbicide degradation seems to be almost insignificant; however, there is a straight relationship between anode composition and organic halides formation. Commercial herbicide formulations have lower degradation rates and lead to the formation of a larger quantities of organochloride compounds. In high chloride concentrations, there is a significant increase in organic mineralization, and the relationship between chloride concentration and organic halides formation is direct. Only in low chloride medium investigated the organochloride concentration obtained was below the limit values allowed in Brazil. The determination of organic halides absorbable (AOX) during electrolysis increases significantly with the applied current. Even during long-term electrolysis, a large amount of organochloride compounds is formed.