670 research outputs found

    History of nematology in Italy

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    Notwithstanding nematology is a rather new science, in Italy the first observations and publications on nematodes date back to several centuries ago and are from physicians and botanists. Among them are U. Aldrovandi (1522-1605), who was the first in the word to observe nematodes in insects, and F. Redi, who published in 1684 his observations about “living animals occurring in living animals”. However, the first observations on plant parasitic nematodes were made from the second half of 1800 to early 1900. They refer to Anguina tritici in wheat kernels (1867), Meloidogyne spp. (1875-1904) on several host plants, Ditylenchus dipsaci (1897) in oats. The sugar beet cyst nematode, Heterodera schachtii, was reported in 1931 and the citrus nematode, Tylenchulus semipenetrans, in 1940. The turning point in Italian plant nematology occurred during 1950-1970, when investigations and control trials started on Xiphinema index, the natural vector of the Grape fan leaf virus. In the same period, the Phytosanitary Service of Pescara addressed much of his efforts on plant parasitic nematodes and the Section of Nematology is established at the Experimental Institute of Agricultural Zoology, of the Ministry of Agriculture, in Florence. Moreover, in 1970, the Italian National Research Councils founded in Bari the Laboratory (later Institute) of Agricultural Nematology Applied to Plants. Later on, nematology attracted also the interest of several other Phytosanitary Services, Universities and firms producing nematicides. While nematology was growing up, research objectives evolved from mainly faunistic and chemical control to many more to encompass all aspects of agricultural nematology and that for number and quality made Italian nematology one of the leading nematology at world level

    THE PHENOMENON OF CYBERCRIME: FROM THE TRANSNATIONAL CONNOTATION TO THE NEED FOR GLOBALIZATION OF JUSTICE

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    Information technology has brought about epochal changes in every area of society, offering opportunities for development on a social, cultural, and economic level, but also a fertile ground for activities with criminal purposes that take place in cyberspace. The threat present in the intangible world of cyberspace is extremely concrete and is one of the major sources of concern and investment by States, given that the Internet is considered the critical infrastructure for excellence. Cybercrime, characterized by a transnational connotation of borderless or aspatial crime, provides a position of advantage to the cybercriminal compared to the traditional criminal. The development of information technologies has led to the digitization of organized crime which thus succeeds in maximizing profits by exploiting the opportunities offered by new communication technologies and minimizing the risk of being identified, arrested, convicted and of suffering the seizure of the proceeds of criminal activities. Considering the contradictory and inhomogeneous international legal framework due to the transnational scope of cybercrime, the identification of the locus commissi delicti is difficult and the legal prosecution of cybercrimes is complex; therefore, cybercriminals could operate without an adequate response from some states in terms of prevention, sanction, containment and contrast. The sovereignty of States, in the context of cybercrime repression, is identified as an insurmountable obstacle in the creation of a supranational union of law. Therefore, to put legal operators in the real conditions to suppress transnational cybercrime, globalization of justice is needed. Article visualizations

    Cosmic Birefringence: Cross-Spectra and Cross-Bispectra with CMB Anisotropies

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    Parity-violating extensions of Maxwell electromagnetism induce a rotation of the linear polarization plane of photons during propagation. This effect, known as cosmic birefringence, impacts on the Cosmic Microwave Background (CMB) observations producing a mixing of EE and BB polarization modes which is otherwise null in the standard scenario. Such an effect is naturally parametrized by a rotation angle which can be written as the sum of an isotropic component α0\alpha_0 and an anisotropic one δα(n^)\delta\alpha(\hat{\mathbf{n}}). In this paper we compute angular power spectra and bispectra involving δα\delta\alpha and the CMB temperature and polarization maps. In particular, contrarily to what happens for the cross-spectra, we show that even in absence of primordial cross-correlations between the anisotropic birefringence angle and the CMB maps, there exist non-vanishing three-point correlation functions carrying signatures of parity-breaking physics. Furthermore, we find that such angular bispectra still survive in a regime of purely anisotropic cosmic birefringence, which corresponds to the conservative case of having α0=0\alpha_0=0. These bispectra represent an additional observable aimed at studying cosmic birefringence and its parity-violating nature beyond power spectrum analyses. They provide also a way to perform consistency checks for specific models of cosmic birefringence. Moreover, we estimate that among all the possible birefringent bispectra, ⟨δα TB⟩\langle\delta\alpha\, TB\rangle and ⟨δα EB⟩\langle\delta\alpha\,EB\rangle are the ones which contain the largest signal-to-noise ratio. Once the cosmic birefringence signal is taken to be at the level of current constraints, we show that these bispectra are within reach of future CMB experiments, as LiteBIRD.Comment: 22 pages, 5 figures; added references; typos corrected; matches published versio

    Probing Axions through Tomography of Anisotropic Cosmic Birefringence

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    Cosmic birefringence is the in-vacuo rotation of the linear polarization plane experienced by photons of the Cosmic Microwave Background (CMB) radiation when theoretically well-motivated parity-violating extensions of Maxwell electromagnetism are considered. If the angle, parametrizing such a rotation is dependent on the photon's direction, then this phenomenon is called Anisotropic Cosmic Birefringence (ACB). In this paper, we perform for the first time a tomographic treatment of the ACB, by considering photons emitted both at the recombination and reionization epoch. This allows one to extract additional and complementary information about the physical source of cosmic birefringence with respect to the isotropic case. We focus here on the case of an axion-like field χ\chi, whose coupling with the electromagnetic sector induces such a phenomenon, by using an analytical and numerical approach (which involves a modification of the CLASS code). We find that the anisotropic component of cosmic birefringence exhibits a peculiar behavior: an increase of the axion mass implies an enhancement of the anisotropic amplitude, allowing to probe a wider range of masses with respect to the purely isotropic case. Moreover, we show that at large angular scales, the interplay between the reionization and recombination contributions to ACB is sensitive to the axion mass, so that at sufficiently low multipoles, for sufficiently light masses, the reionization contribution overtakes the recombination one, making the tomographic approach to cosmic birefringence a promising tool for investigating the properties of this axion-like field.Comment: 24 pages, 5 figures. Added brief information about the algorithms used for reionization and recombination in Fig

    Nematode-wild plant interactions and their implication in nematode management

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    Many species of plant parasitic nematodes are known to have hundreds of host plant species, both cultivated and wild. In the absence of host crop plants, wild plants often are good alternative hosts for the nematodes of which they not only ensure survival but also soil population densities larger than the tolerance levels for different host crop plants. This is known to occur for a few cyst nematodes, such as the sugar beet cyst nematode, Heterodera schachtii, in the presence of several crucifers and chenopodiaceous wild plants, and for many other nematodes known to have rather large host ranges. These include the bulb and stem nematode, Ditylenchus dipsaci, the root-knot nematodes, Meloidogyne spp., and the lesion nematodes, Pratylenchus spp., which have as host plants many wild plants infesting crops during a period of the year suitable for the nematodes. The control of infesting weeds not only improves the growth of the cultivated host plants because of absence of competitors, but also prevents increase of soil nematode densities in their absence and, therefore, may serve as an effective and useful control option of nematodes, especially suggested for inclusion in integrated pest management programmes based on control methods alternative to synthetic nematicides

    Nematode-wild plant interactions and their implication in nematode management

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    Many species of plant parasitic nematodes are known to have hundreds of host plant species, both cultivated and wild. In the absence of host crop plants, wild plants often are good alternative hosts for the nematodes of which they not only ensure survival but also soil population densities larger than the tolerance levels for different host crop plants. This is known to occur for a few cyst nematodes, such as the sugar beet cyst nematode, Heterodera schachtii, in the presence of several crucifers and chenopodiaceous wild plants, and for many other nematodes known to have rather large host ranges. These include the bulb and stem nematode, Ditylenchus dipsaci, the root-knot nematodes, Meloidogyne spp., and the lesion nematodes, Pratylenchus spp., which have as host plants many wild plants infesting crops during a period of the year suitable for the nematodes. The control of infesting weeds not only improves the growth of the cultivated host plants because of absence of competitors, but also prevents increase of soil nematode densities in their absence and, therefore, may serve as an effective and useful control option of nematodes, especially suggested for inclusion in integrated pest management programmes based on control methods alternative to synthetic nematicides

    Cross-Sectional Compactness and Bracing Requirements for Hybrid HPS Girders

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    Current American steel building and bridge design specifications (AISC 1999, AASHTO 1998) simplify the flexural design of both homogeneous and hybrid I-shaped members by treating local and global inelastic stability phenomenon independently. According to both specifications, if a homogeneous or hybrid section is compact and sufficiently braced against lateral instability, the member will achieve or exceed its theoretical plastic moment capacity and maintain this capacity so as to allow sufficient rotation capacity for inelastic force redistribution to take place (Yura et al. 1978). Treating local and global buckling independently has been proven by past experience to be successful when formulating flexural design provisions for lower strength steels. However, new research (Earls 1999, 2000a, 2000b, 2001) is proving that this approach is much more difficult to apply to the design of High Performance Steel (HPS) I-shaped flexural members. The main objective of the current study is to investigate the effect HPS flanges have on hybrid girder flexural ductility. Finite element models of hybrid HPS girders, employing nonlinear shell elements, are used to study the influence of flange slenderness ratios, and bracing configuration on hybrid HPS girder response at ultimate

    Strong and Tough Silk for Resilient Attachment Discs: The Mechanical Properties of Piriform Silk in the Spider Cupiennius salei (Keyserling, 1877)

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    Spiders are able to produce different types of silk with different mechanical and biological properties. Piriform silk is produced to secure spiders and their webs to surfaces by using a nano-fibril network embedded in a cement-like matrix. Despite their fundamental role, the mechanical properties and function of these anchorages are still poorly understood due to the practical difficulties in nano-fibril sample preparation, the complexity of the system, and the high variation of attachment disc structures. Here we estimated the mechanical properties of this nano-fibril silk and those of the whole silk membrane in the large wandering spider Cupiennius salei through a combination of nanoindentation and nanotensile techniques and with the support of a simple analytical model. The results highlight the mechanical properties of the piriform silk, facilitating the modeling of silk composite mechanics. This could inspire the design of more efficient bio-inspired adhesives and fabrics

    Applicazione della normativa ISO26262 a veicoli ibridi elettrici

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    La tesi ha riguardato lo studio e l'applicazione della normativa di sicurezza ISO 26262 a veicoli ibridi elettrici. E' stata svolta una analisi di rischio relativamente ai malfunzionamenti cui può essere soggetta la macchina elettrica, e sono stati sviluppati un sistema di diagnosi e di recupero del guasto al fine di mantenere il veicolo in sicurezza anche in presenza di un guasto

    Magic Sets for Disjunctive Datalog Programs

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    In this paper, a new technique for the optimization of (partially) bound queries over disjunctive Datalog programs with stratified negation is presented. The technique exploits the propagation of query bindings and extends the Magic Set (MS) optimization technique. An important feature of disjunctive Datalog is nonmonotonicity, which calls for nondeterministic implementations, such as backtracking search. A distinguishing characteristic of the new method is that the optimization can be exploited also during the nondeterministic phase. In particular, after some assumptions have been made during the computation, parts of the program may become irrelevant to a query under these assumptions. This allows for dynamic pruning of the search space. In contrast, the effect of the previously defined MS methods for disjunctive Datalog is limited to the deterministic portion of the process. In this way, the potential performance gain by using the proposed method can be exponential, as could be observed empirically. The correctness of MS is established thanks to a strong relationship between MS and unfounded sets that has not been studied in the literature before. This knowledge allows for extending the method also to programs with stratified negation in a natural way. The proposed method has been implemented in DLV and various experiments have been conducted. Experimental results on synthetic data confirm the utility of MS for disjunctive Datalog, and they highlight the computational gain that may be obtained by the new method w.r.t. the previously proposed MS methods for disjunctive Datalog programs. Further experiments on real-world data show the benefits of MS within an application scenario that has received considerable attention in recent years, the problem of answering user queries over possibly inconsistent databases originating from integration of autonomous sources of information.Comment: 67 pages, 19 figures, preprint submitted to Artificial Intelligenc
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