Studio sperimentale degli effetti dei campi elettrici e termici sulla formazione delle bolle di gas in gravità terrestre e progettazione di un apparato per le prove in microgravità

In qesta tesi viene studiato l' effetto che un campo termico o elettrico ha sulla formazione di bolle di gas. Le prove sono state eseguite utilizzando fluidi con densità, tensione superficiale e costante dielettrica diverse. In base ai risultati ottenuti è stato possibile progettare un apparato che può essere utilizzato nella torre di caduta del centro ZARM, a Brema in Germania, per prove in microgravità

Fringe Benefits and Import Competition

In the United States fringe benefits are now more than 30% of compensation. While many studies have focused on the impact of trade with developing countries on U.S. wages, not much attention has been given to the impact of such trade on other components of compensation. But if trade affects the share of benefits in compensation, the studies which focus on wages and ignore fringe benefits likely give us biased estimates of the effect of trade on workers’ total compensation and consumption. I use data about individual workers’ fringe benefits from the NLSY79. I focus on workers who worked in manufacturing in 1991 and I follow them up to 2006. I then combine this individual level dataset with a measure of exposure to Chinese imports at the industry level and with an instrument for it, as in Autor et al. (2014). I estimate the effect of Chinese import competition on fringe benefits to be positive and economically and statistically significant. The results are robust to the inclusion of several individual and industry level control variables. Differently from previous studies, my results suggest a more optimistic view of the effect of trade with China on U.S. workers’ overall compensation

Small-scale desalination plant driven by solar energy for isolated communities

In the last years, an increasing number of countries has been affected by water shortage. Seawater desalination driven by solar energy, which is usually available in arid regions, might be a solution to satisfy the freshwater demand. In this study, the feasibility of a stand-alone multi-effect desalination (MED) plant driven by solar energy for an isolated community was studied. The system was made up of a solar field, a MED unit, and a thermal storage that mitigated solar energy fluctuations. Simulations with different top brine temperature and inclination and number of the solar panels were carried out in Matlab and Aspen Plus on an hourly basis by considering one typical meteorological year for ambient temperature and solar radiation. Two different sources of electrical energy were considered: A photovoltaic (PV) field and a diesel generator. The results were compared from an energetic and economic point of view, by considering the adoption of plastic as a material for MED heat exchangers. The maximum water production was obtained with December as the design month. Polytetrafluoroethylene heat exchangers allowed the cost of water to be reduced up to 9.5% compared to conventional exchangers. The lowest cost of water (7.09 $/m3) was obtained with September as the design month and a tilt angle of 45◦ with the PV field as the electrical power source

Fringe Benefits and Import Competition

In the United States fringe benefits are now more than 30% of compensation. While many studies have focused on the impact of trade with developing countries on U.S. wages, not much attention has been given to the impact of such trade on other components of compensation. But if trade affects the share of benefits in compensation, the studies which focus on wages and ignore fringe benefits likely give us biased estimates of the effect of trade on workers’ total compensation and consumption. I use data about individual workers’ fringe benefits from the NLSY79. I focus on workers who worked in manufacturing in 1991 and I follow them up to 2006. I then combine this individual level dataset with a measure of exposure to Chinese imports at the industry level and with an instrument for it, as in Autor et al. (2014). I estimate the effect of Chinese import competition on fringe benefits to be positive and economically and statistically significant. The results are robust to the inclusion of several individual and industry level control variables. Differently from previous studies, my results suggest a more optimistic view of the effect of trade with China on U.S. workers’ overall compensation

Improving the Environmental Sustainability of Flash Geothermal Power Plants—A Case Study

The sustainability of geothermal energy production is analyzed with reference to a production plant located in a specific area (Monte Amiata, Italy). Four solutions combining a flash power plant with an Organic Rankine Cycle in a hybrid configuration are analyzed in terms of production of electricity, exergy balance and emissions level (CO2, H2S, Hg). The different solutions correspond to increasing environmental performance, and for the most advanced case achieve near-zero emissions (complete reinjection of the natural resource, including incondensable gases). The results show that this can be achieved at the price of a progressive reduction of electrical productivity

Photophysical and photodynamic analysis of different formulations of riboflavin

Background: Riboflavin (Rb) has been used in the ophthalmological procedure known as corneal cross-linking (CXL). Pathologies requiring this treatment include keratoconus, corneal ectasia, and infectious keratitis. Rb is instilled via different molecules that are transported into the tissues. However, each vehicle imparts different properties that alter the photodynamic behavior of Rb, leading to variable concentrations of free radicals within the medium. The objective of this study was to measure the concentrations of free radicals produced by commonly used Rb formulations. To determine the free radical production level of each formulation, L-tryptophan (L-Tryp) was used as a model substrate because it can be efficiently photo-oxidized. Methods: We investigated the photodegradation of L-Tryp and its kinetics upon light exposure. The spectra were recorded using a Shimadzu UV-1800 PC spectrophotometer and a Cary Eclipse fluorescence spectrophotometer. A high-power solid-state LED light source was used for irradiation. L-Tryp degradation was performed using a 9-W LED lamp, and steady-state photolysis was conducted in quartz cells. The observed rate constants for L-Tryp degradation were determined by analyzing the changes in absorbance and fluorescence intensity. Data analysis was performed using Origin software. Results: We examined the characteristics of the photophysical and photodynamic action of the carriers in different commercially available Rb formulations. These included a) Rb with dextran, b) Rb without dextran, c) VibeX Rapid® (hydroxypropylmethylcellulose as a vehicle), d) Trans-Epithelial Kit (I) (sodium chloride as a vehicle), and e) Trans-Epithelial Kit (II) (benzalkonium chloride as a vehicle), using L-Tryp as a model substrate, and focusing on absorption and emission spectra. VibeX Rapid® exhibited the highest photo-degradation constant. The study affirmed the stability of Rb formulations for CXL and highlighted the efficacy of VibeX Rapid® in L-Tryp photo-oxidation and this rationalizes its current use as a CXL agent. Conclusions: We demonstrated that formulations for transport of Rb are of crucial importance in CXL applications. Rb in the VibeX Rapid® formulation is more effective in generating photo-degradation, and this reflects its superior performance in CXL. Future experiments should be designed and conducted to quantitatively differentiate the production of free radicals. Studies involving human participants could shed light on the clinical efficacy and safety of the available Rb formulations

Workers’ Health and Establishment Size

I document the relationship between establishment size and various measures of workers' health. Workers at larger establishments are more likely to have chronic health conditions, have had a bed disability day in the last 12 months and be obese. They are also less likely to be smokers. Results for other health measures depend on the specification. My results may help in more effectively targeting workplace wellness programs. The results may also inform the design of better public interventions aimed at reducing occupational injuries. I discuss the relevance of my results for the establishment size-wage premium

From Bidirectional Associative Memory to a noise-tolerant, robust Protein Processor Associative Memory

AbstractProtein Processor Associative Memory (PPAM) is a novel architecture for learning associations incrementally and online and performing fast, reliable, scalable hetero-associative recall. This paper presents a comparison of the PPAM with the Bidirectional Associative Memory (BAM), both with Kosko's original training algorithm and also with the more popular Pseudo-Relaxation Learning Algorithm for BAM (PRLAB). It also compares the PPAM with a more recent associative memory architecture called SOIAM. Results of training for object-avoidance are presented from simulations using player/stage and are verified by actual implementations on the E-Puck mobile robot. Finally, we show how the PPAM is capable of achieving an increase in performance without using the typical weighted-sum arithmetic operations or indeed any arithmetic operations

Estudio de procesos que ocurren con transferencias de electrones : acople radical-nucleofilo, posibilidades sintéticas

Tesis (Dr. en Ciencias Químicas)-- Universidad Nacional de Córdoba. Facultad de Ciencias Químicas, 2007