Price and Cost Impacts of Concentration in Food Manufacturing Revisited

This study estimates the elasticities of wholesale food prices, cost efficiency, and market power with respect to industrial concentration in 35 food processing industries, modifying the model of Lopez, Azzam, and Lirón-España (2002). In contrast to the results of their earlier analysis, findings of this study indicate that further increases in concentration would result in significant processing cost savings (and Lerner index increases) in nearly all industries and that output prices would decline in nearly 50% of the industries, although significantly so in only 20% of them. As industrial concentration rises, price declines occur in industries with low levels of concentration while price increases occur in highly concentrated industries.cost efficiency, food prices, food processing, industrial concentration, market power, Marketing, Production Economics, Productivity Analysis,

When is Concentration Beneficial?

This paper separates market power and efficiency effects of concentration in a sample of 255 U.S. manufacturing industries and computes welfare changes from rises in concentration. The empirical findings reveal that in nearly two-third of the cases, consumers lose as efficiency gains are generally pocketed by the industries. From an aggregate welfare standpoint, concentration is found to be beneficial in nearly 70% of the cases, mostly for low and moderate levels of concentration being particularly against the public interest in highly concentrated markets. Overall, the results support the existing U.S. Federal Trade Commission guidelines for approval of mergers.concentration, marked power, efficiency, manufacturing, Industrial Organization,

Performance of digital silicon photomultipliers for time of flight PET scanners

The performance of Digital Silicon Photomultipliers (dSiPM) coupled to a LYSO array containing 15×15 pixels with a size of 2×2×22 mm3 is evaluated to determinate their potential for whole body Time of Flight (TOF) PET scanners. The detector pixels are smaller in size than the light sensors and therefore light spreading is required to determine the crystal where interaction occurred. A light guide of 1 mm was used to spread the light and neighbor logic (NL) configuration were employed to ensure correct crystals identification. We studied the energy resolution and coincidence resolving time (CRT) for different trigger levels. The measured average energy resolution across detector was 14.5 %. Prior to measurements of time resolution skew time calibration of dSiPM was performed. The average CRT achieved using trigger level 1 option was 376 ps FWHM. Finally, we studied the amount of events that are disregarded due to dark count effects for different trigger levels and temperatures. Our studies show that a trade-off must be made between the detector’s CRT and sensitivity due to its vulnerability to dark counts. To employ dSiPM in TOF PET systems without 1:1 coupling effective cooling is necessary to limit dark count influence

Clinical consequences of relative biological effectiveness variations in proton radiotherapy of the prostate, brain and liver

Proton relative biological effectiveness (RBE) is known to depend on the (alpha/beta)(x) of irradiated tissues, with evidence of similar to 60% variation over (alpha/beta)(x) values from 1-10 Gy. The range of (alpha/beta)(x) values reported for prostate tumors (1.2-5.0 Gy), brain tumors (10-15 Gy) and liver tumors (13-17 Gy) imply that the proton RBE for these tissues could vary significantly compared to the commonly used generic value of 1.1. Our aim is to evaluate the impact of this uncertainty on the proton dose in Gy(RBE) absorbed in normal and tumor tissues. This evaluation was performed for standard and hypofractionated regimens. RBE-weighted total dose (RWTD) distributions for 15 patients (five prostate tumors, five brain tumors and five liver tumors) were calculated using an in-house developed RBE model as a function of dose, dose-averaged linear energy transfer (LETd) and (alpha/beta)(x). Variations of the dose-volume histograms (DVHs) for the gross tumor volume (GTV) and the organs at risk due to changes of (alpha/beta)(x) and fractionation regimen were calculated and the RWTD received by 10% and 90% of the organ volume reported. The goodness of the plan, bearing the uncertainties, was then evaluated compared to the delivered plan, which considers a constant RBE of 1.1. For standard fractionated regimens, the prostate tumors, liver tumors and all critical structures in the brain showed typically larger RBE values than 1.1. However, in hypofractionated regimens lower values of RBE than 1.1 were observed in most cases. Based on DVH analysis we found that the RBE variations were clinically significant in particular for the prostate GTV and the critical structures in the brain. Despite the uncertainties in the biological input parameters when estimating RBE values, the results show that the use of a variable RBE with dose, LETd and (alpha/beta)(x) could help to further optimize the target dose in proton treatment planning. Most importantly, this study shows that the consideration of RBE variations could influence the comparison of proton and photon treatments in clinical trials, in particular in the case of the prostate