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.

Spatial aspects of trade liberalization in Colombia: A general equilibrium approach

This paper offers some preliminary steps in the marriage of some of the theoretical foundations of new economic geography with spatial computable general equilibrium models. Modelling the spatial economy of Colombia using the traditional assumptions of computable general equilibrium (CGE) models makes little sense when one territorial unit, Bogota, accounts for over one quarter of GDP and where transportation costs are high and accessibility low compared to European or North American standards. Hence, handling market imperfections becomes imperative as does the need to address internal spatial issues from the perspective of Colombia`s increasing involvement with external markets. The paper builds on the Centro de Estudios de Economia Regional (CEER) model, a spatial CGE model of the Colombian economy; non-constant returns and non-iceberg transportation costs are introduced and some simulation exercises carried out. The results confirm the asymmetric impacts that trade liberalization has on a spatial economy in which one region, Bogota, is able to more fully exploit scale economies vis--vis the rest of Colombia. The analysis also reveals the importance of different hypotheses on factor mobility and the role of price effects to better understand the consequences of trade opening in a developing economy.

Adjusting prices in the multiple-partners assignment game

Starting with an initial price vector, prices are adjusted in order to eliminate the excess demand and at the same time to keep the transfers to the sellers as low as possible. In each step of the auction, to which set of sellers should those transfers be made is the key issue in the description of the algorithm. We assume additively separable utilities and introduce a novel distinction by considering multiple sellers owing multiple identical objects and multiple buyers with an exogenously defined quota, consuming more than one object but at most one unit of a seller`s good and having multi-dimensional payoffs. This distinction induces a necessarily more complicated construction of the over-demanded sets than the constructions of these sets for the other assignment games. For this approach, our mechanism yields the buyer-optimal competitive equilibrium payoff, which equals the buyer-optimal stable payoff. The symmetry of the model allows to getting the seller-optimal stable payoff and the seller-optimal competitive equilibrium payoff can then be also derived.

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.

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.

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.

Constipation in intensive care unit: Incidence and risk factors

Purpose: Although gastrointestinal motility disorders are common in critically ill patients, constipation and its implications have received very little attention. We aimed to determine the incidence of constipation to find risk factors and its implications in critically ill patients Materials and Methods: During a 6-month period, we enrolled all patients admitted to an intensive care unit from an universitary hospital who stayed 3 or more days. Patients submitted to bowel surgery were excluded. Results: Constipation occurred in 69.9% of the patients. There was no difference between constipated and not constipated in terms of sex, age, Acute Physiology and Chronic Health Evaluation II, type of admission (surgical, clinical, or trauma), opiate use, antibiotic therapy, and mechanical ventilation. Early (<24 hours) enteral nutrition was associated with less constipation, a finding that persisted at multivariable analysis (P < .01). Constipation was not associated with greater intensive care unit or mortality, length of stay, or days free from mechanical ventilation. Conclusions: Constipation is very common among critically ill patients. Early enteral nutrition is associated with earlier return of bowel function. (C) 2009 Elsevier Inc. All rights reserved.

Price regulation in Australia: How consistent has it been?

We assemble a database consisting of 52 regulatory decisions made by seven different regulators across five different industries. We examine how the proportion of firms' revenue requirements that were disallowed by the regulator vary by regulator, industry and time. Despite the differences in the implementation of price regulation across industries and across jurisdictions in Australia, outcomes are surprisingly consistent. For example, we show that it is not possible to reject the hypothesis that the regulators outcomes in South Australia, New South Wales, the Australian Capital Territory and Victoria are similar despite the different regulatory approaches undertaken in these jurisdictions.

Time- and Fluid-Sensitive Resuscitation for Hemodynamic Support of Children in Septic Shock Barriers to the Implementation of the American College of Critical Care Medicine/Pediatric Advanced Life Support Guidelines in a Pediatric Intensive Care Unit in a Developing World

Objectives: To analyze mortality rates of children with severe sepsis and septic shock in relation to time-sensitive fluid resuscitation and treatments received and to define barriers to the implementation of the American College of Critical Care Medicine/Pediatric Advanced Life Support guidelines in a pediatric intensive care unit in a developing country. Methods: Retrospective chart review and prospective analysis of septic shock treatment in a pediatric intensive care unit of a tertiary care teaching hospital. Ninety patients with severe sepsis or septic shock admitted between July 2002 and June 2003 were included in this study. Results: Of the 90 patients, 83% had septic shock and 17% had severe sepsis; 80 patients had preexisting severe chronic diseases. Patients with septic shock who received less than a 20-mL/kg dose of resuscitation fluid in the first hour of treatment had a mortality rate of 73%, whereas patients who received more than a 40-mL/kg dose in the first hour of treatment had a mortality rate of 33% (P < 0.05.) Patients treated less than 30 minutes after diagnosis of severe sepsis and septic shock had a significantly lower mortality rate (40%) than patients treated more than 60 Minutes after diagnosis (P < 0.05). Controlling for the risk of mortality, early fluid resuscitation was associated with a 3-fold reduction in the odds of death (odds ratio, 0.33; 95% confidence interval, 0.13-0.85). The most important barriers to achieve adequate severe sepsis and septic shock treatment were lack of adequate vascular access, lack of recognition of early shock, shortage of health care providers, and nonuse of goals and treatment protocols. Conclusions: The mortality rate was higher for children older than years, for those who received less than 40 mL/kg in the first hour, and for those whose treatment was not initiated in the first 30 Minutes after the diagnosis of septic shock. The acknowledgment of existing barriers to a timely fluid administration and the establishment of objectives to overcome these barriers may lead to a more successful implementation of the American College of Critical Care Medicine guidelines and reduced mortality rates for children with septic shock in the developing world.

Selective Inner Hair Cell Loss in Prematurity: A Temporal Bone Study of Infants from a Neonatal Intensive Care Unit

Premature birth is a well-known risk factor for sensorineural hearing loss in general and auditory neuropathy in particular. However, relatively little is known about the underlying causes, in part because there are so few relevant histopathological studies. Here, we report on the analysis of hair cell loss patterns in 54 temporal bones from premature infants and a control group of 46 bones from full-term infants, all of whom spent time in the neonatal intensive care unit at the Hospital de Nios in San Jose, Costa Rica, between 1977 and 1993. The prevalence of significant hair cell loss was higher in the preterm group than the full-term group (41% vs. 28%, respectively). The most striking finding was the frequency of selective inner hair cell loss, an extremely rare histopathological pattern, in the preterm vs. the full-term babies (27% vs. 3%, respectively). The findings suggest that a common cause of non-genetic auditory neuropathy is selective loss of inner hair cells rather than primary damage to the cochlear nerve.

Program for Prostate Cancer Screening Using a Mobile Unit: Results From Brazil

OBJECTIVES To evaluate the initial results of a prostate cancer screening program using mobile units in Brazil. METHODS Since 2004, we have conducted a program of prostate cancer screening using mobile units across 231 municipalities from 6 Brazilian states. RESULTS A total of 17 571 men were evaluated by clinical history, digital rectal examination (DRE), and serum free and total prostate-specific antigen (PSA) levels. The recommendations for biopsy were a PSA level of >= 4.0 ng/mL, DRE findings suspicious for cancer, or a PSA level of 2.5-4.0 ng/mL with a percent-free PSA level <15%. The biopsy protocol included 12 biopsy cores from the peripheral zone, 2 from the transition zone, and additional sampling of suspicious areas. The cumulative cancer detection rate was 3.7%. The main indication for biopsy was a PSA level of >= 4.0 ng/mL (51.2%), with a positive predictive value (PPV) of 44.1%. Another 19.7% of biopsied men had suspicious DRE findings with a normal PSA level (PPV 23.5%). A percent-free PSA level of <15% in men with a PSA level of 2.5-4.0 ng/mL and normal DRE findings yielded a PPV of 31.1%. The PPV was greater (70.9%) for the 7.1% of men with both suspicious DRE findings and a PSA level of >4.0 ng/mL. Most cancers were Stage T1-T2 (93.4%), and the percentage of Gleason score of >= 7 was 32.5%. The proportion of insignificant cancers according to Epstein`s criteria was 13.5%. CONCLUSIONS A mobile prostate cancer screening unit enabled an underserved population to gain access to specialized care through the public healthcare system. The cancer detection rate in this population was similar to those from international studies. UROLOGY 76: 1052-1057, 2010. (C) 2010 Published by Elsevier Inc.

Direct measurement of instantaneous source speed for a HDR brachytherapy unit using an optical fiber based detector

Purpose: Several attempts to determine the transit time of a high dose rate (HDR) brachytherapy unit have been reported in the literature with controversial results. The determination of the source speed is necessary to accurately calculate the transient dose in brachytherapy treatments. In these studies, only the average speed of the source was measured as a parameter for transit dose calculation, which does not account for the realistic movement of the source, and is therefore inaccurate for numerical simulations. The purpose of this work is to report the implementation and technical design of an optical fiber based detector to directly measure the instantaneous speed profile of a (192)Ir source in a Nucletron HDR brachytherapy unit. Methods: To accomplish this task, we have developed a setup that uses the Cerenkov light induced in optical fibers as a detection signal for the radiation source moving inside the HDR catheter. As the (192)Ir source travels between two optical fibers with known distance, the threshold of the induced signals are used to extract the transit time and thus the velocity. The high resolution of the detector enables the measurement of the transit time at short separation distance of the fibers, providing the instantaneous speed. Results: Accurate and high resolution speed profiles of the 192Ir radiation source traveling from the safe to the end of the catheter and between dwell positions are presented. The maximum and minimum velocities of the source were found to be 52.0 +/- 1.0 and 17.3 +/- 1:2 cm/s. The authors demonstrate that the radiation source follows a uniformly accelerated linear motion with acceleration of vertical bar a vertical bar = 113 cm/s(2). In addition, the authors compare the average speed measured using the optical fiber detector to those obtained in the literature, showing deviation up to 265%. Conclusions: To the best of the authors` knowledge, the authors directly measured for the first time the instantaneous speed profile of a radiation source in a HDR brachytherapy unit traveling from the unit safe to the end of the catheter and between interdwell distances. The method is feasible and accurate to implement on quality assurance tests and provides a unique database for efficient computational simulations of the transient dose. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3483780]