A Theory of Common Dealing with the Internet as an Innovative Distribution Channel

After the emergence of the Internet, an interesting question arises that what is its impact on the firms’ channel and pricing strategies. This paper applies game theory to study the strategic interactions between rational manufacturers, retailers, and consumers, and it generates the following results: 1. The presence of the Internet allows imperfectly competitive manufacturers to better coordinate their pricing, targeting, and channel strategies, thereby minimizing the agency costs involved in common dealing at the traditional outlets, which in turn enhances the manufacturers’ profits. 2. Exclusive dealing may and may not become more prevalent in the presence of the Internet. It all depends on the ratio of the population of switchers to the entire population of consumers. 3. The presence of the Internet allows a monopolistic manufacturer to screen consumers by serving different people at different outlets. Screening is less effective, however, in the case of imperfect competition. 4. A dynamic adjustment process is obtained which describes how a manufacturer should optimally change his channel and pricing strategies when the population of the Internet purchasers grows over time

Dosimetric verification of vmat dose distribution with DELTA4 Phantom

Radiation Oncology, has changed a great deal, undergoing an innovation and technical development; there has been an evolution from conformal radiotherapy techniques (3D-CRT), through advanced modalities like intensity-modulated radiation therapy (IMRT) and next volumetric modulated arc therapy (VMAT). VMAT technique requires a dedicated QA (Quality Assurance) procedure for dosimetric verification of a planned dose distribution to check for the agreement between a dose distribution calculated by the Treatment Planning System (TPS) and the corresponding measured dose distribution. Since November 2010, in Radiation Therapy Department of “V. Fazzi” hospital in Lecce (Italy), 257 patients were treated with VMAT and the corresponding dose distribution were verified with the Delta4 diode array phantom. Parameters used in the comparison between calculated e measured dose are the dose agreement (DA), the distance to agreement (DTA) and the -index. The phantom measurements closely match the planned dose distributions in high and low dose-gradient region

Atomistic modelling studies of fluorite- and perovskite-based oxide materials

Fast oxide-ion and proton conductors are the subject of considerable research due to their technological applications in sensors, ceramic membranes and solid oxide fuel cells (SOFCs). This thesis describes the use of computer modelling techniques to study point defects, dopants and clustering effects in fluorite-and perovskitetype ion conductors with potential SOFC applications. Bi2O3 related phases are being developed with the objective of high oxide-ion conductivities at lower operating temperatures than 1000°C, as in current generation SOFC electrolytes. Doped Bi2O3 phases have shown promise as materials capable of accomplishing this goal. First, the Y-doped phase, Bi3YO6, has been investigated including the ordering of intrinsic vacancies. The defect and dopant characteristics of Bi3YO6 have been examined and show that a highly mobile oxygen sub-lattice exists in this material. A preliminary structural modelling study of a new Re-doped Bi2O3 phase was also undertaken. A comprehensive investigation of the proton-conducting perovskites BaZrO3, BaPrO3 and BaThO3 is then presented. Our results suggest that intrinsic atomic disorder in BaZrO3 and BaThO3 is unlikely, but reduction of Pr4+ in BaPrO3 is favourable. The water incorporation energy is found to be less exothermic for BaZrO3 than for BaPrO3 and BaThO3, but in all cases the results suggest that the proton concentration would decrease with increasing temperature, in accord with experimental data. The high binding energies for all the dopant-OH pair clusters in BaPrO3 and BaThO3 suggest strong proton trapping effects. Finally, a study of multiferroic BiFeO3 is presented, in which the defect, dopant and migration properties of this highly topical phase are investigated. The reduction process involving the formation of oxygen vacancies and Fe2+ is the most favourable redox process. In addition, the results suggest that oxide-ion migration is anisotropic within this system.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

L’evoluzione tecnologica in Radioterapia: modulazione volumetrica del fascio ed Adaptavtive Radiation Therapy

Le innovazioni in radioterapia sono volte all’aumento del gradiente di dose tra neoplasia e tessuto sano attraverso un miglioramento sia dell’erogazione del fascio sia del controllo dell’errore. La più importante novità nel delivering è la modulazione volumetrica della intensità del fascio. La novità nel controllo dell’errore è rappresentata dalla Adaptative Radiation Therapy (ART), che prevede l’adattamento della distribuzione di dose ad un target mobile o deformabile, seguendo il movimento d’organo (IGRT) e la deformazione e cambio di volume di tumore e degli organi a rischio. La posizione iniziale del target viene riprodotta attraverso il movimento del lettino, il movimento elettronico del fascio, il movimento del braccio dell’acceleratore e la modifica dell’apertura del collimatore. La ART off line individua e corregge errori sistematici che possono avere origine in diverse fasi del processo e si propagano fino alla fine dello stesso, presentandosi in modo identico e ricorrente in ciascuna frazione attraverso il monitoraggio (IGRT) del posizionamento del paziente durante le prime frazioni, allo scopo di adattare i margini di trattamento e/o i piani di trattamento per le restanti sedutesu base individuale. La ART on line corregge errori random (di “esecuzione”), che possono variare di giorno in giorno, poiché si possono presentare in modo diverso per ciascuna frazione del trattamento, attraverso il monitoraggio (IGRT) del posizionamento del paziente durante tutte le frazioni per la misura e la correzione giornaliera degli errori di setup del paziente

SARS-CoV-2 serological profile in healthcare professionals of a Southern Italy hospital

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the first coronavirus that has caused a pandemic. Assessing the prevalence of anti-SARS-CoV-2 in healthcare worker groups offers a unique opportunity to study the correlation between seroconversion and immunization because of their occupational exposure and a higher risk of contagion. The study enrolled 3242 asymptomatic employees of “Policlinico Riuniti”, Foggia. After the first screening, we collected sequential serum samples for up to 23 weeks from the same subjects. In order to perform a longitudinal follow-up study and get information about the titration of IgG levels, we analyzed data from subjects (33) with at least two consecutive serological IgG—positive tests; 62 (1.9%; 95% CI: 1.4–2.3) tested positive for at least one anti-SARS-CoV-2 antibody. The seroprevalence was lower in the high-risk group 1.4% (6/428; 95% CI: 0.5–2.6) vs. the intermediate-risk group 2.0% (55/2736; 95% CI: 1.5–2.5). Overall, within eight weeks, we detected a mean reduction of –17% in IgG levels. Our data suggest a reduction of about 9.27 AU/mL every week (R2 = 0.35, p = 0.0003). This study revealed the prevalence of SARS-CoV-2 antibodies among Foggia’s hospital healthcare staff (1.9%). Moreover, the IgG level reduction suggests that the serological response fades fast in asymptomatic infections

Are radio galaxies and quiescent galaxies different? Results from the analysis of HST brightness profiles

We present a study of the optical brightness profiles of early type galaxies, using a number of samples of radio galaxies and optically selected elliptical galaxies. For the radio galaxy samples--B2 of Fanaroff-Riley type I and 3C of Fanaroff-Riley type II-- we determined a number of parameters that describe a "Nuker-law" profile, which were compared with those already known for the optically selected objects. We find that radio active galaxies are always of the "core" type (i.e. an inner Nuker law slope gamma < 0.3). However, there are core-type galaxies which harbor no significant radio source and which are indistinguishable from the radio active galaxies. We do not find any radio detected galaxy with a power law profile (gamma > 0.5). This difference is not due to any effect with absolute magnitude, since in a region of overlap in magnitude the dichotomy between radio active and radio quiescent galaxies remains. We speculate that core-type objects represent the galaxies that have been, are, or may become, radio active at some stage in their lives; active and non-active core-type galaxies are therefore identical in all respects except their eventual radio-activity: on HST scales we do not find any relationship between boxiness and radio-activity. There is a fundamental plane, defined by the parameters of the core (break radius r_b and break brightness mu_b), which is seen in the strong correlation between r_b and mu_b. The break radius is also linearly proportional to the optical Luminosity in the $I$ band. Moreover, for the few galaxies with an independently measured black hole mass, the break radius turns out to be tightly correlated with M_{BH}. The black hole mass correlates even better with the combination of fundamental plane parameters r_b and mu_b, which represents the central velocity dispersion.Comment: Accepted for publication in A&A, 20 Pages, 9 figure