On the dynamics of bubbles in boiling water

We investigate the dynamics of many interacting bubbles in boiling water by using a laser scattering experiment. Specifically, we analyze the temporal variations of a laser intensity signal which passed through a sample of boiling water. Our empirical results indicate that the return interval distribution of the laser signal does not follow an exponential distribution; contrariwise, a heavy-tailed distribution has been found. Additionally, we compare the experimental results with those obtained from a minimalist phenomenological model, finding a good agreement.Comment: Accepted for publication in Chaos, Solitons & Fractal

Agricultural Production and Technical Change Around the World, 1961-2010

This paper extends the induced innovation research of Hayami and Ruttan by including 129 more countries, extending the time frame to 50 years and explaining the production process for those countries using a Cobb-Douglas function. From this data, the paper illustrates trade-offs between five inputs in agricultural production in empirical isoquants, and measures the progress of agricultural productivity by the magnitude of the shift in isoquants toward the origin. We can further test the implications of technical change on the productivity of the inputs: labor, land, fertilizer, and capital. We illustrate the response of input demands to rising agricultural wages and estimate scale and substitution effects using the fundamental law of derived demand. Lastly, we explore possible explanations for variation in agricultural productivity increases across countries by examining the relationship between countries’ trade protection policies and democracy level and unit labor costs

Relationship between molecular connectivity and carcinogenic activity: a confirmation with a new software program based on graph theory.

For a database of 826 chemicals tested for carcinogenicity, we fragmented the structural formula of the chemicals into all possible contiguous-atom fragments with size between two and eight (nonhydrogen) atoms. The fragmentation was obtained using a new software program based on graph theory. We used 80% of the chemicals as a training set and 20% as a test set. The two sets were obtained by random sorting. From the training sets, an average (8 computer runs with independently sorted chemicals) of 315 different fragments were significantly (p < 0.125) associated with carcinogenicity or lack thereof. Even using this relatively low level of statistical significance, 23% of the molecules of the test sets lacked significant fragments. For 77% of the molecules of the test sets, we used the presence of significant fragments to predict carcinogenicity. The average level of accuracy of the predictions in the test sets was 67.5%. Chemicals containing only positive fragments were predicted with an accuracy of 78.7%. The level of accuracy was around 60% for chemicals characterized by contradictory fragments or only negative fragments. In a parallel manner, we performed eight paired runs in which carcinogenicity was attributed randomly to the molecules of the training sets. The fragments generated by these pseudo-training sets were devoid of any predictivity in the corresponding test sets. Using an independent software program, we confirmed (for the complex biological endpoint of carcinogenicity) the validity of a structure-activity relationship approach of the type proposed by Klopman and Rosenkranz with their CASE program

The influence of the copper content in grape must on alcoholic fermentation kinetics and wine quality. A survey on the performance of 50 commercial Active Dry Yeasts

The effects of copper on the viability and fermentative activity of 50 active dry yeasts purchased on the northern Italian market were studied, and revealed that Copper excess may cause massive death of yeast cells, leading to a significant delay in the start and progress of alcoholic fermentation. A two-log units reduction in cell viability was observed when copper content of musts was around 20 mg∙L-1. Despite this, the difference noted in the kinetics after 20 days' fermentation was lower than that observed 48 hours after in the grape must. An excess of copper in must affected also the composition of the produced wines. The increase in acetic acid and in the sulphur dioxide concentration, observed in wines made using grape must with a high copper concentration, raises serious doubts both regarding the possibility of obtaining good wines from these raw materials and in relation to the progress of subsequent steps of winemaking, such as malolactic fermentation. While it is an important tool in preventing vine diseases, copper must be used very carefully to avoid serious troubles during wine fermentation, even if some yeasts seem more suited to ferment musts containing up to 20-30 mg∙L-1 copper.

On the equivalence of the self-dual and Maxwell-Chern-Simons models coupled to Fermions

We study the exact equivalence between the self-dual model minimally coupled with a Dirac field and the Maxwell-Chern-Simons model with non-minimal magnetic coupling to fermions. We show that the fermion sectors of the models are equivalent only if a Thirring like interaction is included. Using functional methods we verify that, up to renormalizations, the equivalence persists at the quantum level.Comment: 8 pages, revte

Cardiac Autonomic Effects of Yearly Athletic Retreats on Elite Basket Players. Usefulness of a Unitary Autonomic Nervous System Indicator

In most sports athletic performance is determined by a combination of hard and soft modifiable components, encompassing physical and psychological elements that can be assessed with modern techniques based respectively on simple friendly methods: analysis of HRV and questionnaires. Specifically a novel % rank Autonomic Nervous System Indicator (ANSI) seems particularly useful also in elite sports. In this investigation we assessed ANSI capacity to detect the expected changes in cardiac autonomic regulation induced in the Italian basketball team by the participation (18 subjects) to the yearly biweekly Alpine training summer camp. We observed that ANSI increased from 58.8 +/- 32.5 to 81.7 +/- 27.5 (at the end of training camp) and did not change further in the subsequent initial weeks of competition season (overall p &lt; 0.001). Congruent changes were observed in non-linear indices. Concomitantly indices of somatic symptoms were slightly reduced just at the end of the alpine training. We conclude that analysis of HRV and questionnaires might offer a simple, useful technique to monitor changes in cardiac autonomic regulation and psychological state in elite athletes providing a convenient additional element to evaluation of training routines also in the fields