On closures of discrete sets

The depth of a topological space X (g(X)) is defined as the supremum of the cardinalities of closures of discrete subsets of X. Solving a problem of Martínez-Ruiz, Ramírez-Páramo and Romero-Morales, we prove that the cardinal inequality |X|≤g(X)L(X)⋅F(X) holds for every Hausdorff space X, where L(X) is the Lindelöf number of X and F(X) is the supremum of the cardinalities of the free sequences in X

Small-scale flows in SUMER and TRACE high-cadence co-observations

We report on the physical properties of small-scale transient flows observed simultaneously at high cadence with the SUMER spectrometer and the TRACE imager in the plage area of an active region. Our major objective is to provide a better understanding of the nature of transient phenomena in the solar atmosphere by using high-cadence imager and spectrometer co-observations at similar spatial and temporal resolution. A sequence of TRACE Fe IX/X 171 A and high-resolution MDI images were analysed together with simultaneously obtained SUMER observations in spectral lines covering a temperature range from 10 000 K to 1 MK. We reveal the existence of numerous transient flows in small-scale loops (up to 30 Mm) observed in the plage area of an active region. These flows have temperatures from 10 000 K (the low temperature limit of our observations) to 250 000 K. The coronal response of these features is uncertain due to a blending of the observed coronal line Mg X 624.85 A. The duration of the events ranges from 60 s to 19 min depending on the loop size. Some of the flows reach supersonic velocities. The Doppler shifts often associated with explosive events or bi-directional jets can actually be identified with flows (some of them reaching supersonic velocities) in small-scale loops. Additionally, we demonstrate how a line-of-sight effect can give misleading information on the nature of the observed phenomena if only either an imager or a spectrometer is used.Comment: 7 pages, 6 figures, accepted by A&

P-spaces and the Whyburn Property

We investigate the Whyburn and weakly Whyburn property in the class of P-spaces, that is spaces where every countable intersection of open sets is open. We construct examples of non-weakly Whyburn P-spaces of size continuum, thus giving a negative answer under CH to a question of Pelant, Tkachenko, Tkachuk and Wilson. In addition, we show that the weak Kurepa Hypothesis (a set-theoretic assumption weaker than CH) implies the existence of a non-weakly Whyburn P-space of size ℵ2. Finally, we consider the behavior of the above-mentioned properties under products; we show in particular that the product of a Lindelöf weakly Whyburn P-space and a Lindelöf Whyburn P-space is weakly Whyburn, and we give a consistent example of a non-Whyburn product of two Lindelöf Whyburn P-spaces

Sustainability charter for innovative cities and safe mobility. Case study: Sestri Levante

In order to make our cities more innovative and responsive, the paper reports a study aimed at defining a new sustainability tool, in the context of Agenda 2030, to be adopted in urban realities. It has to do with the 'Sustainability Charter', a city decision-making process, designed with researchers, local communities and companies. The research analyses the Sustainability Charter and develops a methodological approach aiming at the systemization of all sustainable actions related to different urban topics. In particular, indicators were identified to assess the sustainability of these topics, graphically represented by chart and defined as sustainability maps. In the paper, among the priority issues at urban level, sustainable mobility is explored. The current health emergency has highlighted all the problems related to urban mobility. This situation can represent an opportunity to improve, revise or update cities\u2019 governance tools. It is necessary to build safe soft mobility infrastructures, and to reorganize the existing ones -redesigning urban space-, by promoting a new culture of sustainable mobility. The Sustainable Urban Mobility Plan (SUMP), should integrate the Urban Sustainability Charter and all the underlying strategies to promote sustainable mobility

Insights in disease management - Editorial

Editorial on the Research Topic Insights in disease management The Research Topic “Insights in Disease Management” brings together innovative Research Topics from the disease management sector. This is a key time to reduce losses to diseases so that we can produce more food that we need for the growing global population but also to control diseases in a way that minimises the environmental footprint of crop production. The issue covers insights using examples in both protected and field crops, covering most pathogen groups – bacteria (Reglinski et al.), viruses (Codod et al.), fungi (Dutta et al.; Sangiorgio et al.), and oomycetes (Sharma et al.). Underpinning many current approaches to disease management is the idea of integrated pest management, which is often portrayed as a triangle representing different tiers of approaches. The foundations of the IPM triangle are practices such as crop rotation to separate crops and pathogens in space and time, use of resistant varieties, and various effects of management practices such as under-sowing or inter-cropping to alter the microclimate, release biofumigants, maintain beneficial microbes or to act as a physical barrier. Papers in this issue connected with this layer of the IPM triangle cover aspects such as improved host resistance with marker-assisted selection, genome sequencing, and improved understanding of resistance genes (Sharma et al.). Also connected to host resistance is the paper by Reglinski et al. except that this concerns host resistance induced by application of a chemical elicitor. This human intervention is preferable to applications of chemical pesticides (usually depicted at the top of the IPM triangle to represent a measure used only as a last resort), which despite often providing efficient disease control and associated benefits of enhanced yield, is acknowledged to have potential non-target effects in the environment. One such non-target effect is the impact of fungicides and other pesticides on microbial endophytes and more broadly, the phytobiome, which Sangiorgio et al. argue, has potential to confer a degree of natural biological control, protecting against pathogens both on the plant surface and within host tissues. They review how genetic sequencing techniques are providing new insights into the degree of protection conferred by the phytobiome towards pathogens in addition to other roles affecting resistance to abiotic stress and nutrient uptake, ultimately affecting plant phenotype, growth, yield and quality. They conclude that future research on plant disease control should also consider impacts to microbe-mediated plant fitness. Indeed, even applications of biological control agents have potential to affect the phytobiome, but this approach is nevertheless regarded as less damaging to the environment compared to chemical control. One of the main biocontrol agents that has been used successfully for over 50 years is Trichoderma. This fungal genus is reviewed by Dutta et al., covering its use as a bio-fungicide, long-term biocontrol agent, defence activator and plant growth stimulator. The use of available biologicals or chemical control options are greatly enhanced by monitoring and forecasting schemes to indicate exactly when the target pathogen will occur. This is increasingly being seen as a form of precision agriculture, directing not only where but also when to make an intervention to protect crops from imminent disease. Various processes have been investigated, ranging from optical sensing from platforms such as satellites, drones or tractor and hand-held devices, to weather-based forecasts, or taking environmental samples (irrigation water, soil or the air) and performing various diagnostic tests, some of which are compatible with being automated and linked to wireless reporting. One key step in determining an efficient sampling or monitoring regime is to understand the spatial distribution of the pest or pathogen in question. The paper by Codod et al. is an example of this – explaining how the whitefly-transmitted virus complex affecting yellow squash (Cucurbita pepo) occurs initially in a sparse, random pattern, mainly around edges of fields but becomes aggregated, with spread mainly along rows, which will inform future developments to improve scouting, monitoring, and management strategies. This issue therefore brings together the core components of IPM, including traditional epidemiological studies, bio-control and cutting-edge ‘omics’, which are currently reshaping IPM, particularly through studies of functional genomics and the microbiome. These approaches are increasingly necessary to deliver sustainable crop production that will feed the world, while having a low environmental impact

Taxonomic remarks and distribution of Smyrnium dimartinoi (Apiaceae)

Smyrnium L., an Eurasian genus of the family Apiaceae, includes about 20 taxa of which only 7 are accepted at specific rank; among these, 5 are native to Europe (Tutin & al. 1968; Gomez 2003). In the Italian flora, the genus is represented by 3 taxa also occurring in Sicily (Pignatti 1982; Giardina & al. 2007); these are Smyrnium olusatrum L., S. perfoliatum L. and S. rotundifolium Mill. The last one has also been treated at the rank of subspecies under S. perfoliatum [S. perfoliatum subsp. rotundifolium (Mill.) Hartvig] (Strid 1986; Conti & al. 2005), or as a variety [S. perfoliatum var. rotundifolium (Mill.)Fiori (Fiori 1925)]. In Sicily, same populations related to S. perfoliatum differ from this taxon for both morphological and ecological characteristics, especially on the Madonie Mountains and the Mountains around Palermo. The study of the morphological characteristics \u2013 namely of the root, stem, and leaf \u2013 allowed to clearly distinguish these populations that, therefore, represented a taxonomically and perhaps even chorologically critical case, since similar plants occurring in Greece were described as S. rotundifolium var. ovatifolium Hal\ue1csy (Hal\ue1csy 1901). In Sicily the same population was finally described as a new species named Smyrnium dimartinoi (Raimondo et al., 2015) to commemorate Andrea Di Martino (1926-2009), professor of botany and director of the Botanical Garden and Herbarium Mediterraneum in the Palermo University. The occurrence of the new taxon related to S. perfoliatum \u2013 ascertained only in Central-Western Sicily and in Crete \u2013 has also been supposed in other countries of the Mediterranean Europe; this, owing to some critical specimens observed in PAL and PAL-Gr. In this contribution, the analytical key of S. perfoliatum group is presented. Furthermore, the geographical distribution of S. dimartinoi is specified after the study of selected exsiccata from other Italian and foreign herbaria. The results found in this research show that S. dimartinoi belongs to the Eurimediterranean element, spread in various countries of the Southern Europe, from Greece to Italy and Spain

Breaking the 400 ppm barrier: Physical and Social implications of the recent CO2 rise

6 p.The concentration of carbon dioxide (CO2) in the atmosphere has achieved its highest levels in the last 800,000 years, and probably even in the last 2.1 million years, recently topping briefly the atmospheric concentration target of 400 ppm. Whereas this mark does not set Earth’s climate in an apocalyptic mode, it does represent a grave global sociopolitical risk, because it highlights the inaction and indifference of government and society to our self-triggered climate changes and their consequences, especially for the poor and the weak. *Since pre-industrial times (i.e. since 1750), atmospheric CO2 concentrations have increased by over 40%, primarily from fossil fuel emissions and decondarily from net land use change emissions, at a rate unprecedented in the last 22,000 years, reaching an average of 2 ppm/ year in the last decade. About 30% of the emitted anthropogenic CO2 has been absorbed by the ocean, causing ocean acidification that poses serious risks to marine ecosystems, resources, and services. *Ice core paleoclimate records teach us that, under typical conditions, global surface temperature never changes much in the long term (of centuries) without a corresponding change in atmospheric CO2 concentration, and vice-versa. In order to explain the amount of warming observed in the temperature records, one must take into account the greenhouse effect caused by the corresponding Atmospheric CO2 concentrations in that period. This does not preclude, however, the occurrence of short-term (decadal) climate variability, which can enhance or counteract the prevailing temperature trend (e.g. the current 15-year hiatus in global temperature rise). *In a business as usual scenario, atmospheric CO2 concentrations by the middle of the 21st century would reach just over 500 ppm, a change of 25% above the present value, which would probably lead to an increase of more than 2ºC in the global mean surface temperature On the other hand, reducing emissions by 2% per year starting no later than 2020 would limit the global carbon dioxide concentration to below 450 ppm. Delaying emission cuts will only enhance the risks of dangerous, and potentially irreversible, climatic changes and increase the costs of future mitigation and adaptation measures

New molecular tool for a quick and easy detection of apple scab in the field

Venturia inaequalis, an agent of apple scab, is the most important pathogen of Malus x domestica. Control measures against this pathogen rely on intensive phytosanitary programs based on predictive models to identify the meteorological conditions conducive to the primary infection. The detection of the pathogen in field, both in naturally infected symptomatic and asymptomatic leaves, is desirable. Loop-mediated isothermal amplification (LAMP) assays are profitable molecular diagnostic tools for the direct detection of pathogens in field. A LAMP assay for V. inaequalis has been designed on the elongation factor 1-alpha sequence. The validation of the LAMP assay was carried out following the international EPPO standard PM 7/98 in terms of specificity, sensitivity, repeatability and reproducibility. Specificity testing was performed using target and non-target species, such as phylogenetically related Venturia species and other pathogens commonly found in apple, resulting in positive amplification only for the target with a time to positive ranging from 20 to 30 min. Sensitivity testing was performed with serial dilutions of DNA of the target and by artificial inoculation of young apple leaves. The reliability of the LAMP assay as an early-detection tool and its user-friendly application make it suitable for the diagnosis of apple scab in the field

DELAMINAZIONE INTERLAMINARE DI COMPOSITI CFRP AL VARIARE DELLE CONDIZIONI DI CURA DELLA MATRICE

In questo lavoro si è condotto uno studio sperimentale del comportamento a delaminazione interlaminare in Modo I di laminati compositi unidirezionali in fibra di carbonio e matrice epossidica (CFRP), al variare delle condizioni di cura della matrice. Tutti i sistemi analizzati hanno utilizzato lo stesso tessuto e lo stesso monomero epossidico DGEBA. Variando il processo di cura (cura termica o mediante radiazioni), gli agenti di cura (ammine o anidridi per i sistemi curati termicamente), e l’impiego di additivi tenacizzanti (es. il PES per i sistemi irradiati), è stato possibile controllare e modificare sia il grado di adesione fibra/matrice, che il grado di fragilità della matrice (monitorato attraverso il Fattore Critico di Intensificazione degli Sforzi KIC). Il lavoro quindi propone una analisi critica dei meccanismi di resistenza alla delaminazione controllati dalla tenacità della matrice e dalla resistenza dell’interfaccia fibra-matrice, mediante la determinazione delle Curve di Resistenza e dei valori di GIC di Innesco e di Propagazione ottenuti per i diversi sistemi presi in esame