Synergies and price trends in sequential auctions

In this paper we consider sequential auctions where an individual’s value for a bundle of objects is either greater than the sum of the values for the objects separately (positive synergy) or less than the sum (negative synergy). We show that the existence of positive synergies implies declining expected prices. When synergies are negative, expected prices are increasing. There are several corollaries. First, the seller is indi¤erent between selling the objects simultaneously as a bundle or sequentially when synergies are positive. Second, when synergies are negative, the expected revenue generated by the simultaneous auction can be larger or smaller than the expected revenue generated by the sequential auction. In addition, in the presence of positive synergies, an option to buy the additional object at the price of the …rst object is never exercised in the symmetric equilibrium and the seller’s revenue is unchanged. Under negative synergies, in contrast, if there is an equilibrium where the option is never exercised, then equilibrium prices may either increase or decrease and, therefore, the net e¤ect on the seller’s revenue of the introduction of an option is ambiguous. Finally, we examine two special cases with asymmetric players. In the …rst case, players have distinct synergies. In this example, even if one player has positive synergies and the other has negative synergies, it is still possible for expected prices to decline. In the second case, one player wants two objects and the remaining players want one object each. For this example, we show that expected prices may not necessarily decrease as predicted by Branco (1997). The reason is that players with singleunit demand will generally bid less than their true valuations in the …rst period. Therefore, there are two opposing forces; the reduction in the bid of the player with multiple-demand in the last auction and less aggressive bidding in the …rst auction by the players with single-unit demand.

Sequential cost-reimbursement rules

This paper studies cost-sharing rules under dynamic adverse selection. We present a typical principal-agent model with two periods, set up in Laffont and Tirole's (1986) canonical regulation environment. At first, when the contract is signed, the firm has prior uncertainty about its efficiency parameter. In the second period, the firm learns its efficiency and chooses the level of cost-reducing effort. The optimal mechanism sequentially screens the firm's types and achieves a higher level of welfare than its static counterpart. The contract is indirectly implemented by a sequence of transfers, consisting of a fixed advance payment based on the reported cost estimate, and an ex-post compensation linear in cost performance.

Sequential auctions with continuation costs

In actual sequential auctions, 1) bidders typically incur a cost in continuing from one sale to the next, and 2) bidders decide whether or not to continue. To investigate the question "when do bidders drop out," we define a sequential auction model with continuation costs and an endogenously determined number of bidders at each sale, and we characterize the equilibria in this modele Simple examples illustrate the effect of several possible changes to this modele

Construção de um aparato experimental para monitoramento in situ da deposição de filmes finos de titânio por magnetron sputtering

The technique of surface coating using magnetron sputtering is one of the most widely used in the surface engineering, for its versatility in obtaining different films as well as in the micro / nanometric thickness control. Among the various process parameters, those related to the active species of the plasma are of the most fundamental importance in the mechanism and kinetics of deposition. In order to identify the active species of the plasma, parameters such as gas flow, pressure and density of electric power were varied during titanium coating on glass substrate. By flowing argon gas of 10, 20, 30, 40 and 50 sccm (cubic centimeters per minute) for each gas flow a sequential scan of the electric current of 0.10, 0.20, 0.30, 0.40 , 0.50 A. The maximum value of 0.50 A was chosen based both on literature data and on limitations of the equipment. The monitoring of plasma species present during the deposition was carried out in situ by the technique of optical emission spectroscopy (OES) through the spectrometer Ocean Optics USB2000 Series. For this purpose, an apparatus was developed to adapt the OES inside the plasma reactor to stay positioned closest to the target. The radiations emitted by the species were detected by an optical fiber placed behind the glass substrate and their intensities as a function of wavelength were, displayed on a monitor screen. The acquisition time for each condition of the plain parameters was related to the minima of spectral lines intensities due to the film formed on the substrate. The intensities of different emission lines of argon and titanium were then analyzed as a function of time, to determine the active species and estimate the thickness of the deposited films. After the deposition, the coated glasses thin films were characterized by optical transmittance through an infrared laser. It was found that the thickness and deposition rate determined by in situ analysis were consistent with the results obtained by laser transmittance

In situ differentiation of labile/inert metal species in Brazilian tropical rivers by means of a time-controlled batch-procedure based on TEPHA resin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Anaerobic bio-digestion of concentrate obtained in the process of ultra filtration of effluents from tilapia processing unit

The objective of the present study was to evaluate the efficiency of the process of biodigestion of the protein concentrate resulting from the ultrafiltration of the effluent from a slaughterhouse freezer of Nile tilapia. Bench digesters were used with excrements and water (control) in comparison with a mixture of cattle manure and effluent from the stages of filleting and bleeding of tilapias. The effluent obtained in the continuous process (bleeding + filleting) was the one with highest accumulated population from the 37th day, as well as greatest daily production. Gases composition did not differ between the protein concentrates, but the gas obtained with the use of the effluent from the filleting stage presented highest methane gas average (78.05%) in comparison with those obtained in the bleeding stage (69.95%) and in the continuous process (70.02%) or by the control method (68.59%).

Aminophylline affects glycemia control and increases anaerobic glycolysis in horses during incremental exercise

A study was conducted on the effects of acute administration of aminophylline on physiological variables in purebred Arabian horses submitted to incremental exercise test. Twelve horses were submitted to two physical tests separated by a 10-day interval in a crossover study. These horses were divided into two groups: control (C, n = 12) and aminophylline (AM, n = 12). The drug at 10 mg/kg body weight or saline was given intravenously, 30 minutes before the incremental exercise test. The treadmill exercise test consisted of an initial warmup followed by gradually increasing physical exigency. Blood samples were assayed for lactic acid, glucose, and insulin. Maximal lactic acidemia was greater (P = .0238) in the AM group. Both V-2 and V-4 (velocities at which lactate concentrations were 2 and 4 mmol/ L, respectively) were reduced in the AM group by 15.85% (P = .0402) and 17.76% (P = .0 109), respectively. At rest as well as at 4 minutes, insulinemia was greater in the AM group (P = .0417 and .0393), Glycemia group at times 8 was statistically lower in the Al (P = .0138) and 10 minutes (P = .0432). Use of ammophylline in horses during incremental exercise does not seem to be beneficial, because this drug has a tendency to cause hypoglycemia and to increase dependence on anaerobic glucose metabolism.

Anaerobic biodigestion of pigs feces in the initial, growing and finishing stages fed with diets formulated with corn or sorghum

Objetivou-se avaliar a produção e a qualidade do biogás e do biofertilizante obtidos em biodigestores abastecidos com dejetos de suínos, nas fases inicial, crescimento e terminação, alimentados com dietas formuladas à base de milho ou sorgo. Foram utilizados 20 biodigestores de bancada, com tempo de retenção hidráulica de 30 dias, e cargas diárias que continham 4,0 a 6,0% de sólidos totais (ST) e 3,6 a 5,2% de sólidos voláteis (SV). Nos efluentes dos biodigestores, foram verificados teores médios de ST variando de 1,6 a 2,0% e de SV entre 1,2 e 1,6%. As reduções médias de ST foram de 57,7 a 64,7% e de SV de 61,7 a 69,0%, sendo que houve diferença somente na fase de terminação, na qual as maiores reduções médias foram para biodigestores abastecidos com dejetos de animais alimentados com dietas à base de milho. Nos biodigestores abastecidos com dejetos de animais em fase inicial e de crescimento, alimentados com dietas formuladas à base de milho, foram verificadas maiores produções médias de biogás e os maiores potenciais médios de produção de biogás. Os potenciais médios obtidos foram 0,033; 0,181; 0,685; 0,788 e 1,132 m³ por kg de afluente, estrume, ST adicionados, SV adicionados e SV reduzidos, respectivamente. Não foram verificadas diferenças quanto ao teor médio de metano no biogás entre dietas e fases. As concentrações médias dos nutrientes N, P, K, Ca, Mg, Na, Fe, Mn, Zn e Cu no afluente e efluente dos biodigestores variaram entre as dietas e fases.

Biodigestão anaeróbia dos dejetos de cabritos Saanen alimentados com dietas com diferentes proporções volumoso e concentrado

Avaliaram-se os efeitos da idade do animal e da proporção de volumoso nas dietas sobre a biodigestão anaeróbia dos dejetos de cabritos Saanen. Foram utilizadas as fezes produzidas por cabritos Saanen aos 90, 120 e 150 dias de idade e alimentados com dietas de três relações volumoso:concentrado (80:20, 60:40 e 40:60), representando as dietas 1, 2 e 3, respectivamente. Utilizaram-se biodigestores tipo batelada de bancada com capacidade para 12 litros de substrato em fermentação e 8% de sólidos totais iniciais para determinação das produções e dos potenciais de produção de biogás e metano, da redução de sólidos voláteis e quantificação dos teores de minerais no afluente e efluente. As maiores reduções de sólidos voláteis foram observadas nos substratos preparados com as fezes de cabritos aos 150 dias alimentados com a dieta com relação volumoso:concentrado de 40:60. Os melhores rendimentos de substrato ou fezes foram obtidos com os dejetos dos cabritos de 120 e 150 dias de idade alimentados com a dieta com relação volumoso:concentrado 40:60. As maiores concentrações de minerais nos biodigestores foram observadas para as fezes de cabritos de 150 dias de idade alimentados com a dieta com relação volumoso:concentrado 40:60. A biodigestão anaeróbia é eficiente na remoção de coliformes nos dejetos de caprinos, proporcionando efluentes com no máximo 4,3 × 10² coliformes totais termotolerantes por grama de material.

Biodigestão anaeróbia de dejetos de caprinos obtidos nas diferentes estações do ano

Foram utilizados dejetos produzidos por caprinos, em diferentes estádios fisiológicos e submetidos ao mesmo regime alimentar, nas quatro estações do ano. O objetivo foi avaliar o efeito das estações do ano sobre a digestão anaeróbia de resíduos de caprinos em biodigestores modelo batelada com volume útil de 60 L de substrato em fermentação e mantidos sob temperatura ambiente. Foram avaliadas as produções de biogás, as reduções de sólidos voláteis (SV), os potenciais de produção (m³ de biogás/kg de substrato, de estrume, de sólidos totais (ST) ou sólidos voláteis), os números mais prováveis de coliformes totais e fecais, e a composição do biogás. As reduções de SV foram de 38; 34; 33 e 39% para o verão, outono, inverno e primavera, respectivamente. Os totais de biogás produzidos foram de 1,06 m³ no verão, 0,88 m³ no outono, 0,88 m³ no inverno e 0,99 m³ na primavera, e os potenciais de produção médios foram de 0,02 m³ de biogás/kg de substrato e 0,2 m³ de biogás/kg de estrume para todas as estações. As reduções médias de coliformes totais e fecais foram de 99,99% em todas as estações, e os teores máximos de CH4 no biogás foram 88,3; 84,6; 80,6 e 79,2%, para o verão, outono, inverno e primavera, respectivamente.

Remoção de matéria orgânica, de nutrientes e de coliformes no processo anaeróbio em dois estágios (reator compartimentado seguido de reator UASB) para o tratamento de águas residuárias de suinocultura

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Parâmetros de dimensionamento para biodigestores batelada operados com dejetos de vacas leiteiras com e sem uso de inóculo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sequential histopathology at the Rhipicephalus sanguineus tick feeding site on dogs and guinea pigs

The tick Rhipicephalus sanguineus is a very common parasite of dogs worldwide. Dogs seem unable to acquire resistance against this tick species, whereas guinea pigs demonstrate a very strong resistance following primary infestation. We studied the inflammatory reaction at the R. sanguineus tick feeding site on dogs and guinea pigs during primary and tertiary infestations at different time intervals after attachment. Biopsies were collected after 4, 24, 48 and 96 hours. Changes that were found in all experimental groups included a cone of cement around the mouthparts of the tick, epidermal hyperplasia, edema and inflammatory cell infiltration in the dermis directly underneath the tick attachment site. Dogs reacted to ticks mainly with neutrophils, particularly after repeated exposure. Mast cells and mononuclear leukocytes were also present. Guinea pigs reacted to R. sanguineus mainly with mononuclear cells, eosinophils and basophils. These cells were particularly numerous after repeated exposure to R. sanguineus. Our results suggest that basophils and eosinophils are involved in resistance of guinea pigs to R. sanguineus and that neutrophils in dogs have little effect against this tick species.

The contribution of genes required for anaerobic respiration to the virulence of Salmonella enterica serovar Gallinarum for chickens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)