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

Strategy for the development of a new stick formula without microplastics

Plastic is a synthetic, malleable, and durable material that has been used for various applications since its invention in the late 19th century. During its very long-time degradation process, mechanical and/or photochemical processes fragment plastic into increasingly smaller fragments called microplastics (MPs). In the cosmetic field, MPs are directly added to many products for various functions, including to exploit their exfoliating and structuring power. Unfortunately, it has been realized that MPs are not retained in purification plants and therefore end up in the aquatic environment causing a high problem of environmental pollution. Polyethene (PE) is the most widely used MP in cosmetics due to its use as a structuring agent, to provide consistency to formulations and as a key ingredient in lipsticks and mascaras. Given the limitations imposed by regulations and the growing demand from consumers for chemical-free and eco-friendly products, the common synthetic and petroleum-based waxes used in lipstick formulations, such as PE, must necessarily be replaced by natural waxes of plant origin. In this paper we report the development of a chemical-free and eco-friendly cosmetic stick. To achieve the goal, it was necessary to study the compatibility of the ABWAX® Revowax, natural alternative to PE, with oils and colours to predict the behaviour of these structuring waxes in more complex systems. Through a systematic comparative study, the two waxes showed similar thermal characteristics and showed similar penetration curves, presenting overall comparable performance in the MP-free finished product. We can therefore consider ABWAX® Revowax natural wax a valid alternative to PE

Does the use of playback affect the estimated numbers of red–legged partridge Alectoris rufa?

¿Afecta el uso de playback a las cifras estimadas de perdiz roja, Alectoris rufa? La perdiz roja, Alectoris rufa, vive en una situación de riesgo potencial en cuanto a su conservación a largo plazo en Italia, dado que su hábitat se ve cada vez más amenazado por la desaparición de los ambientes tradicionalmente relacionados con la agricultura. En tal situación, es importante aplicar métodos de control efectivos para estudiar los cambios poblacionales a través del tiempo, y la identificación de amenazas potenciales a la conservación. El objetivo de este estudio era evaluar la efectividad del método de playback para estimar la densidad de machos que vocalizaban. Comparamos el método del playback con las llamadas espontáneas de los machos al amanecer, y las observaciones directas a lo largo de transectos. El resultado de los datos sin procesar de los recuentos mediante playback revelaron una gran tasa de subestimación, comparados con el método que rindió los mejores resultados: el recuento de vocalizaciones espontáneas al amanecer. Nuestro estudio proporciona una evaluación crítica de un método que está ampliamente extendido, aunque los datos sobre su eficacia son escasos. Nuestros datos no evalúan la probabilidad de detección de los tres métodos. Nuestra intención era únicamente evaluar qué métodos arrojan los mejores resultados en términos de la estimación del tamaño de la población en las mismas condiciones de campo (misma densidad de población, mismo periodo, misma área de monitorización). Los resultados arrojan algunas dudas sobre la capacidad del método del playback para monitorizar las poblaciones de perdiz roja. Se discuten las implicaciones de nuestros resultados para su aplicación en la gestión de poblaciones de perdiz roja.¿Afecta el uso de playback a las cifras estimadas de perdiz roja, Alectoris rufa? La perdiz roja, Alectoris rufa, vive en una situación de riesgo potencial en cuanto a su conservación a largo plazo en Italia, dado que su hábitat se ve cada vez más amenazado por la desaparición de los ambientes tradicionalmente relacionados con la agricultura. En tal situación, es importante aplicar métodos de control efectivos para estudiar los cambios poblacionales a través del tiempo, y la identificación de amenazas potenciales a la conservación. El objetivo de este estudio era evaluar la efectividad del método de playback para estimar la densidad de machos que vocalizaban. Comparamos el método del playback con las llamadas espontáneas de los machos al amanecer, y las observaciones directas a lo largo de transectos. El resultado de los datos sin procesar de los recuentos mediante playback revelaron una gran tasa de subestimación, comparados con el método que rindió los mejores resultados: el recuento de vocalizaciones espontáneas al amanecer. Nuestro estudio proporciona una evaluación crítica de un método que está ampliamente extendido, aunque los datos sobre su eficacia son escasos. Nuestros datos no evalúan la probabilidad de detección de los tres métodos. Nuestra intención era únicamente evaluar qué métodos arrojan los mejores resultados en términos de la estimación del tamaño de la población en las mismas condiciones de campo (misma densidad de población, mismo periodo, misma área de monitorización). Los resultados arrojan algunas dudas sobre la capacidad del método del playback para monitorizar las poblaciones de perdiz roja. Se discuten las implicaciones de nuestros resultados para su aplicación en la gestión de poblaciones de perdiz roja.The red–legged partridge Alectoris rufa lives in a situation of potential conservation risk for its long–term preservation in Italy as its habitat is increasingly threatened by the disappearance of traditional agriculture–related environments. In such a situation, it is important to use effective and appropriate monitoring methods to assess population changes over time and to identify potential conservation threats. The objective of this study was to evaluate the effectiveness of the playback method to estimate the density of calling males. We compared playback method with spontaneous calling of males at dawn and direct observations along transects. The results on raw count data of playback counts revealed a strong underestimation rate compared to the method that gave the best results: count of spontaneous calls at dawn. Our study provides a critical evaluation of a method that is widely used even though data about its effectiveness are scarce. Our data do not evaluate detection probability of the three methods. Our aim was only to evaluate which methods give the best results in term of population size estimation under the same field condition (same population density, same period, same monitoring area). The results raise some doubts about the ability of the playback method to monitor red–legged partridge populations. The implications of our results for red–legged population management are discussed

Numerical simulations of light scattering in soft anisotropic fibrous structures and validation of a novel optical setup from fibrous media characterization

The insight of biological microstructures is at the basis of understanding the mechanical features and the potential pathologies of tissues, like the blood vessels. Different techniques are available for this purpose, like the Small Angle Light Scattering (SALS) approach. The SALS method has the advantage of being fast and non-destructive, however investigation of its physical principles is still required. Within this work, a numerical study for SALS irradiation of soft biological fibrous tissues was carried out through in-silico simulations based on a Monte Carlo approach to evaluate the effect of the thickness of the specimen. Additionally, the numerical results were validated with an optical setup based on SALS technique for the characterization of fibrous samples with dedicated tests on four 3D-printed specimens with different fibers architectures. The simulations revealed two main regions of interest according to the thickness (thk) of the analyzed media: a Fraunhofer region (thk < 0.6 mm) and a Multiple Scattering region (thk > 1 mm). Semi-quantitative information about the tissue anisotropy was successfully gathered by analyzing the scattered light spot. Moreover, the numerical results revealed a remarkable coherence with the experimental data, both in terms of mean orientation and dispersion of fibers

The built environment as determinant of childhood obesity: a systematic literature review

We evaluated the epidemiological evidence on the built environment and its link to childhood obesity, focusing on environmental factors such as traffic noise and air pollution, as well as physical factors potentially driving obesity-related behaviours, such as neighbourhood walkability and availability and accessibility of parks and playgrounds. Eligible studies were i) conducted on human children below the age of 18 years, ii) focused on body size measurements in childhood, iii) examined at least one built environment characteristic, iv) reported effect sizes and associated confidence intervals, and v) were published in English language. A z-Test, as alternative to the meta-analysis, was used to quantify associations due to heterogeneity in exposure and outcome definition. We found strong evidence for an association of traffic-related air pollution (nitrogen dioxide and nitrogen oxides exposure; p<0.001) and built environment characteristics supportive of walking (street intersection density; p<0.01 and access to parks; p<0.001) with childhood obesity. We identified a lack of studies which account for interactions between different built environment exposures or verify the role and mechanism of important effect modifiers such as age

Phase noise mitigation in photonics-based radio frequency multiplication

Two photonics-based radio frequency multiplication schemes for the generation of high-frequency carriers with low phase noise are proposed and experimentally demonstrated. With respect to conventional frequency multiplication schemes, the first scheme induces a selective cancelation of phase noise at periodic frequency-offset values, whereas the second scheme provides a uniform 3-dB mitigation of phase noise. The two schemes are experimentally demonstrated for the generation of a 110-GHz carrier by sixfold multiplication of an 18.3-GHz carrier. In both cases, the experimental results confirm the phase noise reduction predicted by theory

New strategies for Botrytis bunch rot control for a sustainable viticulture

Grapevine (Vitis vinifera L.) is cultivated throughout the world in a wide range of climates, from temperate to tropical ones. It’s highly susceptible to fungi, being Botrytis cinerea (Bc) among the most important pathogens causing bunch rot (BR), a disease mostly observed on ripe berries, normally controlled through use of chemicals. To date, the defence against Bc is still guaranteed by an intensive use of chemical fungicides. Consequently, the development of alternative strategies for Bc control with benefits both for human health and the environment is of high importance and a priority. In the last years, the concept of “integrated defence” against Bc is increasingly widespread, using defence protocols integrating agronomic control tools with interventions based on synthetic fungicides and natural antagonists to be carried out in the periods of higher susceptibility. In this project, a molecular method for monitoring Bc load in the field was setted-up in order to quantify the colonization by Bc of vineyards of V. vinifera cv Sangiovese and Trebbiano at different locations (hilly site vs plain site) and cultivated applying different integrated defence protocols against Bc. Samples at were collected at three different developmental stages (full flowering, bunch enclosure and veraison) from different biological replicates of different thesis of treatment and molecularly analyzed calculating the colonization coefficient for each sample. The correlation between molecular data with BcBR severity and incidence data at harvest in the different thesis for the two cultivars are here presented. The molecular assay will be useful both to quantify Bc load at the early season in order to predict BcBR severity at harvest, and more in general to evaluate the effect of disease management protocols adopted on the reduction of Bc inoculum

Logarithmic diffusion and porous media equations: a unified description

In this work we present the logarithmic diffusion equation as a limit case when the index that characterizes a nonlinear Fokker-Planck equation, in its diffusive term, goes to zero. A linear drift and a source term are considered in this equation. Its solution has a lorentzian form, consequently this equation characterizes a super diffusion like a L\'evy kind. In addition is obtained an equation that unifies the porous media and the logarithmic diffusion equations, including a generalized diffusion equation in fractal dimension. This unification is performed in the nonextensive thermostatistics context and increases the possibilities about the description of anomalous diffusive processes.Comment: 5 pages. To appear in Phys. Rev.