719 research outputs found

    TRACE and ground-based observations of microflares

    Get PDF
    We present high temporal and spatial resolution, multiwavelength observations of small-scale activity phenomena. The data were obtained during a coordinated campaign between ground-based and space observatories. Our analysis supports the concept that small flares are just miniature flares, i.e. that the same physical processes are at work, but that it is mandatory to have an excellent resolution in order to clearly identify them. In particular, we find that chromospheric downward motions are a very distinctive characteristic of the flare phenomenon even in tiny events

    Flare model sensitivity of the Balmer spectrum

    Get PDF
    Careful studies of various chromospheric spectral signatures are very important in order to explore their possible sensitivity to the modifications of the thermodynamic quantities produced by the flare occurrence. Pioneer work of Canfield and co-workers have shown how the H alpha behavior is able to indicate different changes in the atmospheric parameters structure associated to the flare event. It was decided to study the behavior of the highest Balmer lines and of the Balmer continuum in different solar flare model atmospheres. These spectral features, originating in the deep photosphere in a quiet area, may have a sensitivity different from H alpha to the modification of a flare atmosphere. The details of the method used to compute the Stark profile of the higher Balmer line (n is greater than or equal to 6) and their merging were extensively given elsewhere (Donati-Falchi et al., 1985; Falchi et al., 1989). The models used were developed by Ricchiazzi in his thesis (1982) evaluating the chromospheric response to both the nonthermal electron flux, for energy greater than 20 kev, (F sub 20) and to the thermal conduction, (F sub c). The effect of the coronal pressure values (P sub O) at the apex of the flare loop is also included

    Helium Line Formation and Abundance in a Solar Active Region

    Get PDF
    An observing campaign (SOHO JOP 139), coordinated between ground-based and Solar and Heliospheric Observatory (SOHO) instruments, has been planned to obtain simultaneous spectroheliograms of the same active region in several spectral lines. The chromospheric lines Ca ii K, H , and Na i D, as well as He i 10830, 5876, 584, and He ii 304 8 lines have been observed. The EUV radiation in the range k < 500 8 and in the range 260 < k < 340 8 has also been measured at the same time. These simultaneous observations allow us to build semiempirical models of the chromosphere and low transition region of an active region, taking into account the estimated total number of photoionizing photons impinging on the target active region and their spectral distribution. We obtained a model that matches very well all the observed line profiles, using a standard value for the He abundance (½He ¼ 0:1) and a modified distribution of microturbulence. For this model we study the influence of the coronal radiation on the computed helium lines. We find that, even in an active region, the incident coronal radiation has a limited effect on the UV He lines, while it is of fundamental importance for the D3 and 10830 8 lines. Finally, we build two more models, assuming values of He abundance ½He ¼ 0:07 and 1.5, only in the region where temperatures are >1 ; 104 K. This region, between the chromosphere and transition region, has been indicated as a good candidate for processes that might be responsible for strong variations of [He]. The set of our observables can still be well reproduced in both cases, changing the atmospheric structure mainly in the low transition region. This implies that, to choose between different values of [He], it is necessary to constrain the transition region with different observables, independent of the He lines.Fil: Mauas, Pablo Jacobo David. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Andretta, V.. Osservatorio Astronomico di Capodimonte; ItaliaFil: Falchi, A.. Osservatorio Astrofisico di Arcetri; ItaliaFil: Falciani, R.. Universita Degli Studi Di Firenze; ItaliaFil: Teriaca, L.. Max-Planck-Institut fur Sonnensystemforschung; AlemaniaFil: Cauzzi, G.. Osservatorio Astrofisico di Arcetri; Itali

    A deep learning-based pipeline for whitefly pest abundance estimation on chromotropic sticky traps

    Get PDF
    Integrated Pest Management (IPM) is an essential approach used in smart agriculture to manage pest populations and sustainably optimize crop production. One of the cornerstones underlying IPM solutions is pest monitoring, a practice often performed by farm owners by using chromotropic sticky traps placed on insect hot spots to gauge pest population densities. In this paper, we propose a modular model-agnostic deep learning-based counting pipeline for estimating the number of insects present in pictures of chromotropic sticky traps, thus reducing the need for manual trap inspections and minimizing human effort. Additionally, our solution generates a set of raw positions of the counted insects and confidence scores expressing their reliability, allowing practitioners to filter out unreliable predictions. We train and assess our technique by exploiting PST - Pest Sticky Traps, a new collection of dot-annotated images we created on purpose and we publicly release, suitable for counting whiteflies. Experimental evaluation shows that our proposed counting strategy can be a valuable Artificial Intelligence-based tool to help farm owners to control pest outbreaks and prevent crop damages effectively. Specifically, our solution achieves an average counting error of approximately compared to human capabilities requiring a matter of seconds, a large improvement respecting the time-intensive process of manual human inspections, which often take hours or even days

    Boosting grapevine breeding for climate-smart viticulture: from genetic resources to predictive genomics

    Get PDF
    The multifaceted nature of climate change is increasing the urgency to select resilient grapevine varieties, or generate new, fitter cultivars, to withstand a multitude of new challenging conditions. The attainment of this goal is hindered by the limiting pace of traditional breeding approaches, which require decades to result in new selections. On the other hand, marker-assisted breeding has proved useful when it comes to traits governed by one or few genes with great effects on the phenotype, but its efficacy is still restricted for complex traits controlled by many loci. On these premises, innovative strategies are emerging which could help guide selection, taking advantage of the genetic diversity within the Vitis genus in its entirety. Multiple germplasm collections are also available as a source of genetic material for the introgression of alleles of interest via adapted and pioneering transformation protocols, which present themselves as promising tools for future applications on a notably recalcitrant species such as grapevine. Genome editing intersects both these strategies, not only by being an alternative to obtain focused changes in a relatively rapid way, but also by supporting a fine-tuning of new genotypes developed with other methods. A review on the state of the art concerning the available genetic resources and the possibilities of use of innovative techniques in aid of selection is presented here to support the production of climate-smart grapevine genotypes

    Population variability in some genes involving the haemostatic system: data on the general population of Corsica (France), Sardinia and Sicily (Italy)

    Get PDF
    Three different population samples from Corsica (France), Sardinia and Sicily (Italy) were studied using nine genetic markers. For the first time, allele distributions of FGA TaqI, FGB Bcl I, FGB Hind III, PAI-1 Hind III, PLAT TPA-25, GPIIIa Taq I, GPIIb I/D 9bp, FVII HVR4 and FVII -323 10 bp markers, which are thought to be associated with cardiovascular disease risk, were studied in the general population of the three islands. The frequencies of the markers analysed in the present work show some peculiarities: the locus FVII HVR4 is characterized by the presence of a rare allele (H5), found in Corsicans and in Sardinians; the locus FBG BcII shows a low frequency of the B1 allele and the absence of the B1B1 genotype. The frequencies of some alleles have a distribution that is in agreement with the low risk for cardiovascular diseases in south European countries. The results highlight a genetic differentiation between the three Mediterranean islands and the other European populations
    • …
    corecore