Bioregulators Application in Pear Production

This short review report the results obtained with the main plant growth regulators/plant bioregulators (PGRs or PBRs) that are currently tested or used as registered pre-harvest and post-harvest compounds. The PBRs used in pre-harvest concern the regulation of fruit setting, bearing, fruit thinning and of shoot growth control. The auxin-like compounds are mainly used for fruit set and for pre-harvest drop control; Gibberellins for fruit set; auxins and citokinins for fruit thinning/quality improvement and prohexadione-Ca (Regalis) for shoot growth and fire-blight control. The PBRs for improving fruit quality and storability can be used in pre- and post-harvest. Aminoethoxyvinylglycine (AVG) is used in pre-harvest while 1- methylcyclopropene (1-MCP) can be used in cold storage room or, in some countries, also in pre-harvest (Harvista) to affect fruit post-harvest maturation and storability management

Evolution of rotating stars with PARSEC: implementation and comparison with observations

The goal of this thesis is to study the effects of stellar rotation onto the evolution of stars.o this purpose, I have dedicated a good part of my PhD to study and implement the main rotation effects on our stellar evolutionary code parsec (PAdova tRieste Stellar Evolutionary Code). The first project in which I was involved was to investigate the possible concurrence between the convective core overshooting phenomenon and the rotation in intermediate-mass stars. For such study, I analyzed a sample of double-line eclipsing binaries (DLEBs, with very well determined masses radii and metallicities) by means of a Bayesian method and the new parsec v2.0 rotating tracks. This study allowed me to calibrate the overshooting efficiency in the code and to conclude that a constant efficiency of overshooting in concurrence with a star-to-star variation of the rotational mixing might be crucial in the interpretation of intermediate-mass stars observations. The second project consisted of a study of the effects of rotation in the stellar photometry. As the rotation grows the star becomes more and more oblate, this induces a thermal imbalance between the poles and the equator that is known as the Von Zeipel effect. Rotating stars do not have a constant effective temperature along the surface and for higher rotational velocity such difference increases. Since the temperature is proportional to the emitted flux, a fast-rotating star will look very different if observed at the pole or at the equator (this is also called gravity darkening). In this work, we developed a tool to compute the rotating isochrones with the gravity darkening. This work is fundamental to interpret the observed stellar clusters CMD and their features that are emerging thanks to the recent excellent photometry provided by the extit{Hubble Space Telescope} (HST). These two projects have been fundamental steps in the building of a new collection of tools to study stellar clusters populations. My third project was the first attempt to use these tools to analyze the Large Magellanic Cloud (LMC) stellar cluster NGC~1866. Instead of looking at individual features in the CMD, like the split main sequence (MS), eMSTO, and evolved stars, we seek to reinterpret the entire available data, in particular exploiting Cepheids that have accurate pulsational mass determinations. I found that four Cepheids out of five, belong to a young (of $176 pm 5$~Myr) and slowly rotating (omegai~ < 0.3) population, while the fifth belongs to an older population (of $288 pm 20$~Myr) of rapidly rotating stars (omegai~$sim 0.9$). Later, I fitted the observed CMD of the cluster with isochrones with selected ages and initial rotations obtained from the Cepheids analysis and corrected with the gravity darkening effect. I found that the two isochrones well fit the split-MS and the cluster turn-off. This study goes in the direction to confirm that some young clusters like NGC~1866 harbour multiple populations, but gives also hints on its formation

Impact of Estimation Uncertainty in PMU-Based Resynchronization of Continental Europe Synchronous Areas

Power system stability is a task that every system operator (SO) is required to achieve daily to ensure an uninterruptible power supply. Especially at the transmission level, for each SO it is of utmost importance to ensure proper exchange of information with other SOs, mainly in case of contingencies. However, in the last years, two major events led to the splitting of Continental Europe into two synchronous areas. These events were caused by anomalous conditions which involved in one case the fault of a transmission line and in the other a fire outage in proximity to high-voltage lines. This work analyzes these two events from the measurement point of view. In particular, we discuss the possible impact of estimation uncertainty on control decisions based on measurements of instantaneous frequency. For this purpose, we simulate five different configurations of phasor measurement units (PMUs), as characterized by different signal models, processing routines, and estimation accuracy in the presence of off-nominal or dynamic conditions. The objective is to establish the accuracy of the frequency estimates in transient conditions, more specifically during the resynchronization of the Continental Europe area. Based on this knowledge, it is possible to set more suitable conditions for resynchronization operations: the idea is to consider not only the frequency deviation between the two areas but also to take into account the respective measurement uncertainty. As confirmed by the analysis of the two real-world scenarios, such an approach would allow for minimizing the probability of adverse or even dangerous conditions such as dampened oscillations and inter-modulations

Formation of black holes in the pair-instability mass gap: evolution of a post-collision star

The detection of GW190521 by the LIGO-Virgo collaboration revealed the existence of black holes (BHs) in the pair-instability (PI) mass gap. Here, we investigate the formation of BHs in the PI mass gap via star -- star collisions in young stellar clusters. To avoid PI, the stellar-collision product must have a relatively small core and a massive envelope. We generate our initial conditions from the outputs of a hydro-dynamical simulation of the collision between a core helium burning star ($\sim 58$ M$_\odot$) and a main-sequence star ($\sim 42$ M$_\odot$). The hydro-dynamical simulation allows us to take into account the mass lost during the collision ($\sim 12$ M$_\odot$) and to build the chemical composition profile of the post-collision star. We then evolve the collision product with the stellar evolution codes PARSEC and MESA. We find that the post-collision star evolves through all the stellar burning phases until core collapse, avoiding PI. At the onset of core collapse, the post-collision product is a blue super-giant star. We estimate a total mass loss of about 1 M$_\odot$ during the post-collision evolution, due to stellar winds and shocks induced by neutrino emission in a failed supernova. The final BH mass is $\approx{87}$ M$_\odot$. Therefore, we confirm that the collision scenario is a suitable formation channel to populate the PI mass gap.Comment: 9 pages, 6 figures, comments welcome

Comparative transcriptomic analysis of plum fruit treated with 1-MCP

Microarray technology has allowed the large scale transcriptomic analysis of fruit ripening. The μPEACH1.0 microarray containing 4,806 probes corresponding to genes expressed in peach fruit tissues has been used in a heterologous fashion in two studies of plums ripening behavior. Gene expression of different cultivars of plums treated with the ethylene antagonist, 1-methylcyclopropene (1-MCP) and stored for short periods at room temperature or for longer periods of cold storage was examined. In the first study, mature fruit of a suppressed ethylene climacteric cultivar 'Shiro' and a cultivar characterized by a typical increase of ethylene production during ripening ('Santa Rosa') were harvested and incubated for 24h in air (control) or 1-MCP and allowed to ripen at room temperature. Different levels of transcripts of genes implicated in cell wall metabolism, hormone (ethylene and auxin) regulation, stress and defense, and in the transcription/translation machinery, as well as others involved with ripening were identified. In the second study, the effects of 1-MCP on gene expression in relation to the development of chilling injury (CI) in the climacteric cultivars 'Ruby Red' (RR) and 'October Sun' (OS) and 'Zee Lady' peaches (ZP) were analyzed. The fruit were treated for 24h at room temperature with 1-MCP prior to storage at 0°C. For RR, there was no significant effect of 1-MCP on the level of CI symptoms, while 1-MCP significantly reduced CI symptoms in OS fruit and an increase of CI in treated ZP fruit. Microarray analysis showed that immediately following treatment, 186, 134 and 56 genes were differentially expressed between the control and 1-MCP-treated fruit of these cultivars, respectively: after 4 weeks cold storage, 311, 52 and 224 genes for RR, OS and ZP, respectively, were differentially expressed between control and treated fruit. Thus, for OS, the number of differentially expressed genes reduced during storage while the number increased in RR and ZP. Comparisons of the data suggest that the transcript profile is altered by 1-MCP more in plums than peaches. These studies, carried out within an international collaborative network, will increase our understanding of the regulation of pathways involved in plum fruit ripening and in metabolic processes related to storage and shelf lif

Merging black hole binaries with the SEVN code

Studying the formation and evolution of black hole binaries (BHBs) is essential for the interpretation of current and forthcoming gravitational wave (GW) detections. We investigate the statistics of BHBs that form from isolated binaries, by means of a new version of the SEVN population-synthesis code. SEVN integrates stellar evolution by interpolation over a grid of stellar evolution tracks. We upgraded SEVN to include binary stellar evolution processes and we used it to evolve a sample of 1.5 x 10(8) binary systems, with metallicity in the range [10(-4); 4 x 10(-2)]. From our simulations, we find that the mass distribution of black holes (BHs) in double compact-object binaries is remarkably similar to the one obtained considering only single stellar evolution. The maximum BH mass we obtain is similar to 30, 45, and 55 M-circle dot at metallicity Z = 2 x 10(-2), 6 x 10(-3), and 10(-4), respectively. A few massive single BHs may also form (less than or similar to 0.1 per cent of the total number of BHs), with mass up to similar to 65, 90, and 145 M-circle dot at Z = 2 x 10(-2), 6 x 10(-3), and 10(-4), respectively. These BHs fall in the mass gap predicted from pair-instability supernovae. We also show that the most massive BHBs are unlikely to merge within a Hubble time. In our simulations, merging BHs like GW151226 and GW170608, form at all metallicities, the high-mass systems (like GW150914, GW170814, and GW170104) originate from metal-poor (Z less than or similar to 6 x 10(-3)) progenitors, whereas GW170729-like systems are hard to form, even at Z = 10(-4). The BHB merger rate in the local Universe obtained from our simulations is similar to 90Gpc(-3)yr(-1), consistent with the rate inferred from LIGO-Virgo data

On the photometric signature of fast rotators

Rapidly rotating stars have been recently recognized as having amajor role in the interpretation of colour-magnitude diagrams of young and intermediate-age star clusters in the Magellanic Clouds and in the Milky Way. In this work, we evaluate the distinctive spectra and distributions in colour-colour space that follow from the presence of a substantial range in effective temperatures across the surface of fast rotators. The calculations are inserted in a formalism similar to the one usually adopted for non-rotating stars, which allows us to derive tables of bolometric corrections as a function not only of a reference effective temperature, surface gravity and metallicity, but also of the rotational speed with respect to the break-up value, omega, and the inclination angle, i. We find that only very fast rotators (omega &gt; 0.95) observed nearly equator-on (i&gt;45 degrees) present sizable deviations from the colour-colour relations of non-rotating stars. In light of these results, we discuss the photometry of the similar to 200-Myr-old cluster NGC 1866 and its split main sequence, which has been attributed to the simultaneous presence of slow and fast rotators. The small dispersion of its stars in colour-colour diagrams allows us to conclude that fast rotators in this cluster either have rotational velocities omega&lt;0.95, or are all observed nearly pole-on. Such geometric colour-colour effects, although small, might be potentially detectable in the huge, high-quality photometric samples in the post-Gaia era, in addition to the evolutionary effects caused by rotation-induced mixing

181 Studies on Fruit Thinning and Growth in Apple Cultivars

Experiments were carried out for 3 years on `Gala' and `Fuji' apple cultivars. The efficacy of the compounds applied during blooming (ATS, Armothin) and at 10 mm king fruit diameter (BA, CPPU, and NAA) was studied. Results showed a poor efficacy of the chemicals applied during bloom, while compounds applied at fruit set showed interesting results. Among the new chemicals, citokinins were the most effective, although their effects were related to the cultivar: BA performs better than CPPU on `Fuji' while vice versa on `Gala'. In addition, both chemicals induced a slightly higher °Brix content, and acidity level showed the tendency to increase L/D ratio of the fruits as compared to controls. Fruit thinning and the strategies to enhance fruit size are applied early in the season and the problem remains, to assess their effectiveness as early as possible in order to adapt the management techniques (e.g., further thinning, if applicable, or fine-tuning of nutrition and irrigation, etc.) to enable the fruit to reach their maximum potential development. A modelling approach proposed by Lakso et al. (1995) postulates that apples grow in weight according to an equation termed "expolinear" (Goudriaan and Monteith, 1990) because after an initial phase of exponential growth (cell division), the apple enters a phase of linear growth (cell expansion) lasting up to harvest. The effectiveness of a thinning agent can therefore be evaluated-and explained-in terms either of the number of cells of the cortex tissue, or of their volume, or both. In addition, assessing the slope of the linear phase as early as possible might provide a prediction tool to evaluate size at harvest. This paper presents data from apple thinning trials on several cultivars. The effectiveness of these applications has been evaluated via an analysis of the cell parameters (number, volume and intercellular spaces) of the fruit's parenchyma cortex tissue. Also, fruit growth data have been used to test the possibility to predict fruit size at harvest once the fruit reaches the phase of linear growth

Micro-scale {UHI} risk assessment on the heat-health nexus within cities by looking at socio-economic factors and built environment characteristics: The Turin case study (Italy)

Today the most substantial threats facing cities relate to the impacts of climate change. Extreme temperature such as heat waves and the occurrence of Urban Heat Island (UHI) phenomena, present the main challenges for urban planning and design. Climate deterioration exacerbates the already existing weaknesses in social systems, which have been created by changes such as population increases and urban sprawl. Despite numerous attempts by researchers to assess the risks associated with the heat-health nexus in urban areas, no common metrics have yet been defined yet. The objective of this study, therefore, is to provide an empirical example of a flexible and replicable methodology to estimate the micro-scale UHI risks within an urban context which takes into account all the relevant elements regarding the heat-health nexus. For this purpose, the city of Turin has been used as a case study. The methodological approach adopted is based on risk assessment guidelines suggested and approved by the most recent scientific literature. The risk framework presented here used a quantitative estimate per each census tract within the city based on the interaction of three main factors: hazard, exposure, and vulnerability. Corresponding georeferenced maps for each indicator have been provided to increase the local knowledge on the spatial distribution of vulnerability drivers. The proposed methodology and the related findings represent an initial stage of the urban risk investigation within the case study. This will include participatory processes with local policymakers and health-stakeholders with a view to guiding the local planning agenda of climate change adaptation and resilience strategies in the City of Turin

Massive binary black holes from Population II and III stars

Population III stars, born from the primordial gas in the Universe, lose a negligible fraction of their mass via stellar winds and possibly follow a top-heavy mass function. Hence, they have often been regarded as the ideal progenitors of massive black holes (BHs), even above the pair instability mass gap. Here, we evolve a large set of Population III binary stars (metallicity $Z=10^{-11}$) with our population-synthesis code SEVN, and compare them with Population II binary stars ($Z=10^{-4}$). In our models, the lower edge of the pair-instability mass gap corresponds to a BH mass of $\approx{86}$ ($\approx{91}$) M$_\odot$ for single Population III (II) stars. Overall, we find only mild differences between the properties of binary BHs (BBHs) born from Population III and II stars, especially if we adopt the same initial mass function and initial orbital properties. Most BBH mergers born from Population III and II stars have primary BH mass below the pair-instability gap, and the maximum secondary BH mass is $< 50$ M$_\odot$. Only up to $\approx{3.3}$% ($\approx{0.09}$%) BBH mergers from Population III (II) progenitors have primary mass above the gap. Unlike metal-rich binary stars, the main formation channel of BBH mergers from Population III and II stars involves only stable mass transfer episodes in our fiducial model.Comment: 15 pages, 17 figures, comments are welcom