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Kiwifruit vine artificial pollination was firstly studied in New Zealand and in Italy in the 80s in order to optimize the kiwifruit fruit set and production. Nowadays it is a crucial technique useful to increase fruit quality and size. However, artificial pollination efficiency depends on the timing of application and the pollination system. The main objective of this study is to decipher the relation between the floral stage and the pollination technique. Many parameters were analyzed in different environments in Italy for many years, such as pollen quality (germinability, humidity, conservation), pollination system (dry or liquid) and flowering stage. The petals fall and full bloom-early petal fall stages result in the best moments for dry and liquid pollination respectively. The dry blower pollination system gave the best results because, at the end of flowering, the pistil exudate is at its maximum and a larger number of ovaries are receptive with respect to the liquid pollination at full bloom. This observation leads to the definition of a new model crop fruit set that could be applied in other anemophilous pollinated tree such as olive tree, hazelnut, pistachio.

Pseudomonas syringae pv. actinidiae (Psa), the causal agent of bacterial canker of kiwifruit, was first isolated in 1989. A pandemic outbreak that started in 2008 is seriously threatening kiwifruit production worldwide. Very little is known about the molecular mechanisms involved in this host-pathogen interaction. In this study, an RNAseq approach was applied to identify the virulence genes of Psa involved in pathogenicity. Transcriptome analysis was carried out on Psa grown in LB medium (PsaLB) or in LB medium supplemented with plant extracts of Actinidia deliciosa (PsaAd) or Actinidia chinensis (PsaAc). Differential gene expression analysis under all three tested conditions highlighted widespread transcriptional modulation, with up to 2000 genes listed as significantly differentially expressed genes (DEGs), which represents about half of the total number of Psa genes. Many of the genes found to be upregulated in Psa cells exposed to plant extracts were involved in functions such as motility, chemotaxis, adherence and iron acquisition, which are functions associated with plant colonization. However, under the PsaAd and PsaAc conditions, genes coding for the type-III secretion system and type-III effector proteins, which are known to be essential for virulence of P. syringae, were downregulated. These data suggest that regulation of the expression of type-III secretion system genes was dependent on plant signals distinct from those that control expression of genes involved in motility, and invasion and might require direct interaction with plant cells in intact tissue.

Background Since 2007, bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) has become a pandemic disease leading to important economic losses in every country where kiwifruit is widely cultivated. Options for controlling this disease are very limited and rely primarily on the use of bactericidal compounds, such as copper, and resistance inducers. Among the latter, the most widely studied is acibenzolar-S-methyl. To elucidate the early molecular reaction of kiwifruit plants (Actinidia chinensis var. chinensis) to Psa infection and acibenzolar-S-methyl treatment, a RNA seq analysis was performed at different phases of the infection process, from the epiphytic phase to the endophytic invasion on acibenzolar-S-methyl treated and on non-treated plants. The infection process was monitored in vivo by confocal laser scanning microscopy. Results De novo assembly of kiwifruit transcriptome revealed a total of 39,607 transcripts, of which 3360 were differentially expressed during the infection process, primarily 3 h post inoculation. The study revealed the coordinated changes of important gene functional categories such as signaling, hormonal balance and transcriptional regulation. Among the transcription factor families, AP2/ERF, MYB, Myc, bHLH, GATA, NAC, WRKY and GRAS were found differentially expressed in response to Psa infection and acibenzolar-S-methyl treatment. Finally, in plants treated with acibenzolar-S-methyl, a number of gene functions related to plant resistance, such as PR proteins, were modulated, suggesting the set-up of a more effective defense response against the pathogen. Weighted-gene coexpression network analysis confirmed these results. Conclusions Our work provides an in-depth description of the plant molecular reactions to Psa, it highlights the metabolic pathway related to acibenzolar-S-methyl-induced resistance and it contributes to the development of effective control strategies in open field. Electronic supplementary material The online version of this article (10.1186/s12864-018-4967-4) contains supplementary material, which is available to authorized users.

Prunus, in particular peach, is considered one of the most recalcitrant species for what concerns in vitro regeneration, especially when the starting plant material originates from mature tissues. Furthermore, in terms of peach genetic transformation, few examples exist in literature and most of them demonstrate the difficulty in obtaining stable transformants. The present study describes an efficient method of in vitro regeneration, via organogenesis, starting from meristematic bulk tissues, characterized by a high competence to produce adventitious shoots and useful for genetic transformation of Prunus persica cultivar 'Big Top® Zaitabo*' and rootstock GF677. This protocol constitutes one of the few examples of peach in vitro regeneration starting from adult tissue present in the literature. It has been used to genetically transform the rootstock GF677 and the cultivar 'Big Top® Zaitabo*', through the development of two different methods of transformation, one mediated by Agrobacterium tumefaciens, applied on slices from meristematic bulk, and the other by the biolistic technique applied on slices from meristematic bulks and on vegetative apex. The transformation experiments were conducted using hairpin genetic constructs for the induction of Plum pox virus (PPV) resistance through the mechanism of post-transcriptional gene silencing (PTGS). To our knowledge, this is the first example of a successful attempt of a peach rootstock and cultivar stable genetic transformation and it represents a good promise for the future production of silenced GF677 plants to be tested for the capacity to induce PPV resistance also in the grafted scion.

Flowers can provide a protected and nutrient-rich environment to the epiphytic microflora, thus representing a sensible entry point for pathogens such as Pseudomonas syringae pv. actinidiae (Psa). This bacterium can colonize both male and female Actinidia flowers, causing flower browning and fall, and systemic invasion of the host plant, eventually leading to its death. However, the process of flower colonization and penetration into the host tissues has not yet been fully elucidated. In addition, the presence of Psa in the pollen from infected flowers, and the role of pollination in the spread of Psa requires confirmation. The present study employed a Psa strain constitutively expressing the fluorescent GFPuv protein, to visualize in vivo flower colonization. Microscopy observations were performed by means of confocal laser scanning and wide-field fluorescent microscopy, and were coupled with the study of Psa population dynamics by quantitative PCR (q-PCR). The pathogen was shown to colonize stigmata, move along the stylar furrow, and penetrate the receptacles via the style or nectarhodes. Once the receptacle was invaded, the pathogen migrated along the flower pedicel and became systemic. Psa was also able to colonize the anthers epiphytically and endophytically. Infected male flowers produced contaminated pollen, which could transmit Psa to healthy plants. Finally, pollinators (Apis mellifera and Bombus terrestris) were studied in natural conditions, showing that, although they can be contaminated with Psa, the pathogen’s transmission via pollinators is contrasted by its short survival in the hive.

A vine decline of kiwifruit (A. deliciosa ‘Hayward’) was observed in 2012 and 2013 in about 600 ha in the province of Verona (Northern Italy). During the last two years, a progressive vine decline took place during summers with high temperatures (over 35°C) requiring copious furrow irrigation, and with mild temperatures and abundant rainfall during winter and spring that caused long periods of soil waterlogging. The diseased plants died after a gradual blight of the leaves. Rotting of the roots intermediate in diameter and of the distal rootlets were associated with all cases of decline. Phytophthora and Pythium species were isolated from the decayed roots, were plate purified and identified by sequence analysis of the internal transcribed spacer (ITS) region of the rDNA amplified with specific primers. Pathogenicity of the Phytophthora isolates was verified with experimental inoculations of kiwi plantlets. Typical symptoms of the decline in the leaves were caused by isolates of Phytophthora cryptogea. This is the first report of Phytophthora and Pythium presence in plants with root rot and vine decline of kiwifruit in Northern Italy associated to anomalous climate condition.

The collection of soil and climate data from kiwifruit orchards can constitute a reference for the proper management of kiwifruit cultivation, in particular for control of Pseudomonas syringae pv. actinidiae (Psa), plant nutrition and irrigation. The optimization of irrigation, fertilization, and copper treatment resulted in sustainable production of kiwifruit at reduced costs. The climate monitoring system can also be applied in field trials to study diseases epidemiology and orchard management.

Background In this study we carried out a genome-wide association analysis for plant and grain morphology and root architecture in a unique panel of temperate rice accessions adapted to European pedo-climatic conditions. This is the first study to assess the association of selected phenotypic traits to specific genomic regions in the narrow genetic pool of temperate japonica. A set of 391 rice accessions were GBS-genotyped yielding—after data editing—57000 polymorphic and informative SNPS, among which 54% were in genic regions. Results In total, 42 significant genotype-phenotype associations were detected: 21 for plant morphology traits, 11 for grain quality traits, 10 for root architecture traits. The FDR of detected associations ranged from 3 · 10−7 to 0.92 (median: 0.25). In most cases, the significant detected associations co-localised with QTLs and candidate genes controlling the phenotypic variation of single or multiple traits. The most significant associations were those for flag leaf width on chromosome 4 (FDR = 3 · 10−7) and for plant height on chromosome 6 (FDR = 0.011). Conclusions We demonstrate the effectiveness and resolution of the developed platform for high-throughput phenotyping, genotyping and GWAS in detecting major QTLs for relevant traits in rice. We identified strong associations that may be used for selection in temperate irrigated rice breeding: e.g. associations for flag leaf width, plant height, root volume and length, grain length, grain width and their ratio. Our findings pave the way to successfully exploit the narrow genetic pool of European temperate rice and to pinpoint the most relevant genetic components contributing to the adaptability and high yield of this germplasm. The generated data could be of direct use in genomic-assisted breeding strategies.

Cultivated European rice germplasm is generally characterized by moderate to high sensitivity to blast, and blast resistance is therefore one of the most important traits to improve in rice breeding. We collected a panel of 25 rice genotypes containing 13 broad range rice resistance genes that are commonly used in breeding programs around the world: Pi1, Pi2, Pi5, Pi7, Pi9, Pi33, Pib, Pik, Pik-p, Pita, Pita 2 , Piz and Piz-t. The efficiency of the selected Pi genes towards Italian blast pathotypes was tested via artificial inoculation and under natural field infection conditions. To characterize haplotypes present in the chromosomal regions of the blast resistance genes, a polymorphism search was conducted in the sequence regions adjacent to the blast resistance by examining DNA from the Pi gene donors with a panel of 5–7 potential receivers (cultivated European rice genotypes). Seven InDel and 8 presence/absence polymorphisms were directly detected by gel analysis after DNA amplification, while sequencing of 12.870 bp through 32 loci in different genotypes revealed 85 SNP (one SNP every 151 bp). Seven SSRs were additionally tested revealing 5 polymorphic markers between donors and receivers. Polymorphisms were used to develop 35 PCR-based molecular markers suitable for introgressing of Pi genes into a set of the European rice germplasm. For this last purpose, allelic molecular marker variation was evaluated within a representative collection of about 95 rice genotypes. Polymorphic combinations allowing introgression of the broad spectrum resistance genes into a susceptible genetic background have been identified, thus confirming the potential of the identified markers for molecular-assisted breeding.

Leaf stripe of barley, caused by Pyrenophora graminea, is an important seed-borne disease in organically grown as well as in conventionally grown Nordic and Mediterranean barley districts. Two barley segregating populations represented by 103 recombinant inbred lines (RILs) of the cross L94 (susceptible) × Vada (resistant) and 194 RILs of the cross Arta (susceptible) × Hordeum spontaneum 41-1 (resistant) were analysed with two highly virulent leaf stripe isolates, Dg2 and Dg5, to identify loci for P. graminea resistance. A major gene with its positive allele contributed by Vada and H. spontaneum 41-1 was detected in both populations and for both pathogen isolates on chromosome 2HL explaining 44.1 and 91.8% R 2, respectively for Dg2 and Dg5 in L94 × Vada and 97.8 and 96.1% R 2, respectively for Dg2 and Dg5 in Arta × H. spontaneum 41-1. Common markers in the gene region of the two populations enabled map comparison and highlighted an overlapping for the region of the resistance locus. Since the map position of the resistance locus identified in this report is the same as that for the leaf stripe resistance gene Rdg1a, mapped earlier in Alf and derived from the ‘botanical’ barley line H. laevigatum, we propose that leaf stripe resistance in Vada and H. spontaneum 41-1 is governed by the same gene, namely by Rdg1a, and that Rdg1a resistance could be traced back to H. spontaneum, the progenitor of cultivated barley. PCR-based molecular markers that can be used for marker-assisted selection (MAS) of Rdg1a were identified. An Rdg1a syntenic interval with the rice chromosome arm 4L was identified on the basis of rice orthologs of EST-based barley markers. Analysis of the rice genes annotated into the syntenic interval did not reveal sequences strictly belonging to the major class (nucleotide-binding site plus leucine-rich repeat) of the resistance genes. Nonetheless, four genes coding for domains that are present in the major disease-resistance genes, namely receptor-like protein kinase and ATP/GTP-binding proteins, were identified together with a homolog of the barley powdery mildew resistance gene mlo. Three (out of five) homologs of these genes were mapped in the Rdg1a region in barley and the mlo homolog map position was tightly associated with the LOD score peak in both populations.

Aim The present study focused on nine patients with hepatocellular carcinoma (HCC) associated with Child A liver cirrhosis undergoing first-line liver resection and salvage liver transplantation (SLT) for liver tumor recurrence. Patients and methods Forty-six patients with HCC underwent liver transplantation (OLT); 37 (80.5%) were primary liver transplantations (PLTs) and 9 (19.5%) were SLTs. All patients who underwent SLT received minor transabdominal liver resections. Results The posttransplant 1-, 3-, and 5-year overall survival rates for SLT (88.9%, 88.9%, and 88.9%) were similar to those for PLT (78%, 62.7%, and 62.7%). Four (10.8%) patients in the PLT group had HCC recurrence, while there was zero recurrence in the SLT group. The 1-, 3-, 5-year disease-free survival rates for PLT (89%, 74%, and 74%) were similar to those for SLT (100%, 100%, and 100%). The 1-, 3-, 5-year disease-free survival rates after PLT were 89%, 74%, and 74%, and after SLT were 100%, 100%, and 100%, respectively. The operative mortality, intraperioperative bleeding, operative time, intensive care unit stay, in-hospital stay, and overall incidence of postoperative complications were similar in the two groups. Conclusions In our experience, SLT for HCC is a feasible procedure with similar results in terms of overall survival, disease-free survival, and postoperative complications to those reported for patients who underwent PLT at our institute. An important role exists for SLT as shown by the fact that such a strategy has been used in the 20% of the patients undergoing OLT for HCC.

Aims: The aim of this study was to examine the effect of Melaleuca alternifolia essential oil (TTO) and its principal components on four cereal-pathogenic fungi. Methods and Results: The antimycotic properties of TTO and of terpinen-4-ol, γ-terpinen and 1,8-cineole (eucalyptol) were evaluated in vitro on Fusarium graminearum, Fusarium culmorum and Pyrenophora graminea. Moreover, barley leaves infected with Blumeria graminis were treated with whole TTO. All the tested fungi were susceptible to TTO and its components. Conclusions: TTO exerted a wide spectrum of antimycotic activity. Single TTO purified components were more active than the whole oil in reducing in vitro growth of fungal mycelium and, among the tested compounds, terpinen-4-ol was the most effective. Significance and Impact of the Study: TTO and its components can be considered potential alternative natural fungicides.

The authors describe the performance of a multi-sensor package designed to measure the electromagnetic properties of the subsurface during future landing missions to Mars. The package consists of a soil dielectric spectroscopy probe (SDSP), a ground penetrating radar (GPR) and a time domain electromagnetic measurement (TDEM) system that, using different methods, estimate the electromagnetic properties of the shallow subsurface at different depths (0– 100 m ). A data fusion approach is considered to improve the reliability and accuracy of the measurements.

Pyrenophora graminea is the seed-borne pathogen causal agent of barley leaf stripe disease. Near-isogenic lines (NILs) carrying resistance of the cv ”Thibaut” against the highly virulent isolate Dg2 were obtained by introgressing the resistance into the genetic background of the susceptible cv ”Mirco”. The segregation of the resistance gene was followed in a F2 population of 128 plants as well as on the F3 lines derived from the F2 plants; the segregation fitted the 1:2:1 ratio for a single gene. By using NILs, a RAPD marker associated with the resistance gene was identified; sequence-specific (STS) primers were designed on the basis of the amplicon sequence and a RILs mapping population with an AFLP-based map were used to position this molecular marker to barley chromosome 1 S (7HS). STS and CAPS markers were developed from RFLPs mapped to the telomeric region of barley chromosome 7HS and three polymorphic PCR-based markers were developed. The segregation of these markers was followed in the F2 population and their map position with respect to the resistance gene was determined. Our results indicate that the Thibaut resistance gene, which we designated as Rdg2a, maps to the telomeric region of barley chromosome 7HS and is flanked by the markers OPQ-9700 and MWG 2018 at distances of 3.1 and 2.5 cM respectively. The suitability of the PCR-based marker MWG2018 in selection- assisted barley breeding programs is discussed.

The barley Rdg2a locus confers resistance to the leaf stripe pathogen Pyrenophora graminea and, in the barley genotype Thibaut, it is composed of a gene family with three highly similar paralogs. Only one member of the gene family (called as Rdg2a) encoding for a CC-NB-LRR protein is able to confer resistance to the leaf stripe isolate Dg2. To study the genome evolution and diversity at the Rdg2a locus, sequences spanning the Rdg2a gene were compared in two barley cultivars, Thibaut and Morex, respectively, resistant and susceptible to leaf stripe. An overall high level of sequence conservation interrupted by several rearrangements that included three main deletions was observed in the Morex contig. The main deletion of 13,692 bp was most likely derived from unequal crossing over between Rdg2a paralogs leading to the generation of a chimeric Morex rdg2a gene which was not associated to detectable level of resistance toward leaf stripe. PCR-based analyses of genic and intergenic regions at the Rdg2a locus in 29 H. vulgare lines and one H. vulgare ssp. spontaneum accession indicated large haplotype variability in the cultivated barley gene pool suggesting rapid and recent divergence at this locus. Barley genotypes showing the same haplotype as Thibaut at the Rdg2a locus were selected for a Rdg2a allele mining through allele re-sequencing and two lines with polymorphic nucleotides leading to amino acid changes in the CC-NB and LRR encoding domains, respectively, were identified. Analysis of nucleotide diversity of the Rdg2a alleles revealed that the polymorphic sites were subjected to positive selection. Moreover, strong positively selected sites were located in the LRR encoding domain suggesting that both positive selection and divergence at homologous loci are possibly representing the molecular mechanism for the generation of high diversity at the Rdg2a locus in the barley gene pool.

MicroRNAs (miRNAs) are short non-coding RNA molecules produced from hairpin structures and involved in gene expression regulation with major roles in plant development and stress response. Although each annotated miRNA in miRBase (www.mirbase.org) is a single defined sequence with no further details on possible variable sequence length, isomiRs - namely the population of variants of miRNAs coming from the same precursors - have been identified in several species and could represent a way of broadening the regulatory network of the cell. Next-gen-based sequencing makes it possible to comprehensively and accurately assess the entire miRNA repertoire including isomiRs. The aim of this work was to survey the complexity of the peach miRNome by carrying out Illumina high-throughput sequencing of miRNAs in three replicates of five biological samples arising from a set of different peach organs and/or phenological stages. Three hundred-ninety-two isomiRs (miRNA and miRNA*-related) corresponding to 26 putative miRNA coding loci, have been highlighted by mirDeep-P and analyzed. The presence of the same isomiRs in different biological replicates of a sample and in different tissues demonstrates that the generation of most of the detected isomiRs is not random. The degree of mature sequence heterogeneity is very different for each individual locus. Results obtained in the present work can thus contribute to a deeper view of the miRNome complexity and to better explore the mechanism of action of these tiny regulators.

The outflow venovenous anastomosis represent a crucial aspect during orthotopic liver transplantation (OLT) with inferior vena cava (IVC) preservation. The modified Belghiti liver hanging maneuver applied to the last phase of hepatectomy, lifting the liver, provides a better exposure of the suprahepatic region and allows easier orthogonal clamping of the three suprahepatic veins with a minimal portion of IVC occlusion. The outflow anastomosis constructed with a common cloacae of the three native suprahepatic veins is associated with a lower incidence of graft related venous outflow complications. The procedure planned in 120 consecutive OLT was achieved in 118 (99%). The outflow anastomosis was constructed on the common cloaca of the three hepatic veins in 111/120 cases (92.5%). No major complications were observed (bleeding during tunnel creation, graft outflow dysfunction, etc) except in one patient with acute Budd-Chiari, who successfully underwent retransplantation.

Many reports have claimed that the duration of the swelling cycle in female bonobos (Pan paniscus) is longer than that of chimpanzees, and that the bonobo maximum swelling phase is markedly prolonged. Field data on intermenstrual intervals (IMIs) in female bonobos are limited and restricted to interswelling intervals (ISIs), which are assumed to reflect the IMI, though a direct comparison between the duration of ISIs and IMIs is still lacking. Reports on bonobo sexual activity as a function of the swelling phase are often contradictory. Moreover, the function of female homosexual interactions (genito-genital (GG) rubbing) is still debated. This study examines the reliability of the ISI as an approximation of the IMI, and the attractivity of female sexual swellings for other individuals. An analysis of 51 ISI-IMI pairs showed that ISIs are a fair representation of the reproductive cycle. The cycle length was 35.6±1.1 SE days relying on the ISI, whereas it was 35.0±1.1 SE days considering the IMI. This result is similar to the cycle length reported for chimpanzees. Female homosexual interactions and copulatory rates were higher during maximum tumescence, suggesting that the sexual swelling may be attractive for both males and other females. Furthermore, the GG-rubbing was performed free of a hierarchical postural imposition, and was not correlated with affinitive interactions. We suggest that GG-rubbing, which is generally the most frequent female sexual interaction, is a tool for social assessments among females. Am. J. Primatol. 67:333–347, 2006. © 2006 Wiley-Liss, Inc.

This paper explores the applicability of reconfigurable control techniques to an AUV (Autonomous Underwater Vehicle). The development of a reconfigurable control system for an underwater vehicle is intended to achieve overall reliability, maintainability and safe operation without resorting to excessive component redundancy. The underwater vehicle is modelled as a linear multivariable system controlled by means of a number of hydroplanes, rudders and propellers. Typical mission tasks are considered and different types of faults are taken into account, which regard sensors and or actuators. The efficiency of a number of reconfigurable control strategies are considered and compared with respect to the level of system performance degradation. Such strategies are comprehensive of the following steps: - robust multivariable LQG design - on-line monitoring and fault detection - optimal control reconfiguration

Genetic mapping of major genes and quantitative traits loci (QTLs) for many important agricultural traits is increasing the integration of biotechnology with the conventional breeding process. Exploitation of the information derived from the map position of traits with agronomical importance and of the linked molecular markers, can be achieved through marker assisted selection (MAS) of the traits during the breeding process. However, empirical applications of this procedure have shown that the success of MAS depends upon several factors, including the genetic base of the trait, the degree of the association between the molecular marker and the target gene, the number of individuals that can be analyzed and the genetic background in which the target gene has to be transferred. MAS for simply inherited traits is gaining increasing importance in breeding programs, allowing an acceleration of the breeding process. Traits related to disease resistance to pathogens and to the quality of some crop products are offering some important examples of a possible routinary application of MAS. For more complex traits, like yield and abiotic stress tolerance, a number of constraints have determined severe limitations on an efficient utilization of MAS in plant breeding, even if there are a few successful applications in improving quantitative traits. Recent advances in genotyping technologies together with comparative and functional genomic approaches are providing useful tools for the selection of genotypes with superior agronomical performancies.

The dominant gene Rdg2a of barley conferring resistance to the hemi-biotrophic seed-borne pathogen Pyrenophora graminea is located in the distal region of chromosome arm 1 (7H)S. As the first step towards isolating the gene, a high-resolution genetic map of the region was constructed using an F(2) population of 1,400 plants (Thibaut Rdg2axMirco). The map included six classes of resistance gene analogues (RGAs) tightly associated with Rdg2a. Rdg2a was delimited to a genetic interval of 0.14 cM between the RGAs ssCH4 and MWG851. Additional markers were generated using the sequence from the corresponding region on rice chromosome 6, allowing delimitation of the Rdg2a syntenic interval in rice to a 115 kbp stretch of sequence. Analysis of the rice sequence failed to reveal any genes with similarity to characterized resistance genes. Therefore, either the rice-barley synteny is disrupted in this region, or Rdg2a encodes a novel type of resistance protein.

This paper presents the project TESEO (TEM sounding for Geophysical Exploration) for planetary TEM (Time Electromagnetic Methods) survey, focused on the main issue of the search for water on Mars. The project aims to extend the TEM (largely and successfully employed on the Earth) to the planetary environment, where the many unknown variables (above all the background EM noise and the subsoil composition), together with the limited resources availability (mission constraints in mass, time and power) pose a formidable obstacle to performing operations and measurements. In such a context, we first investigated the opportunity for a TEM system to be housed as a payload in a future mission with special attention given to those ones deploying a network of carrier (landers, rovers, robots). Secondly, we evaluated the sounding capability of a TEM for a simple case study verifying the role played by the system and survey parameters.

Statistical mathematical models arising from the acoustic scattering of an underwater object are derived. Global and local models that are obtained by the singularity expansion method are considered. A parametric inverse problem is formulated on the basis of ARMAX models. The related identification algorithms and parameter estimation problems are examined, and an identification algorithm is developed for the multistatic case. >

Within the framework of the Tethered Satellite System (TSS-1) Project (bilateral cooperation between NASA and ASI, the Italian Space Agency) a measurement programme on the electromagnetic background noise has been carried out. From theoretical consideration on the cold plasma theory in the ionosphere, the expected frequency band of these emissions should be from about 1 Hz up to 60 Hz. The paper outlines some recently proposed applications of nonGaussian signal processing techniques based on higher order statistics, which can be usefully applied to ELF (extremely low frequency) electromagnetic noise characterization for detection and parameter estimation purposes. >

This paper is originated from the desire to obtain classification and characterization of a vast category of signals which have been ignored in conventional classical applications, like the ones concerning shipping traffic underwater noise. Current interest in the field of communications, the falling price of personal computers (based on 80486 or pentium), and the availability of extremely high level languages, have lead the authors to develop this work. The paper is documented in several stages: initially the non parametric and parametric approach, for the nongaussian and nonlinear signal processing are described, and proposed by system which divides interferences sources into classes A, B and C is introduced. In order to achieve to the main goal of the present paper various mathematical techniques have been adopted such as example the bispectrum approach (H.O.S. Theory), and Gabor expansion. After the nonlinearity identification due to transient signals, the processing system is applied to class B interferences. Although the heavy computational complexity in various stages, i.e. the calculation of the coefficients used for the Gabor processing and the routine for the bispectrum estimation, the results confirm the wide extendibility of the D. Middleton approach. This work has been developed in the contest of the MAST-I-SNECOW Project ( Shipping Noise Evaluation in Coastal Waters) of the European Community Marine Science and Technology Program. >

This paper aims to provide realistic modelling of generic noise probability density functions (pdfs). The target is to obtain a parametric model depending on few parameters, and being so general to be able to describe many kinds of noise (e.g., symmetric or asymmetric, with variable sharpness). A very general and easy-to-use function which is based on HOS parameters is presented and compared with other HOS-based pdfs; it is called asymmetric generalized Gaussian. A real case study is considered for comparing the various pdfs; it consists in modelling real underwater acoustic noise at low frequencies and applying the estimated models to designed locally optimum detection (LOD) tests.

During two different space missions involving tethered satellites, two ground measurement experiments were performed. The aim of both experiments was the observation at the Earth's surface of spontaneous and man-made emissions propagating from the orbiting system through the Earth-ionosphere cavity. The first one was carried out in July 1992 on Tenerife (Canary island, Spain), within the framework of the ASI (Italian Space Agency) and NASA mission STS46-TSSI (Tethered Satellite System 1). The second one, related to NASA-PMG (Plasma Motor Generator) space mission, was carried out at Hilo, Hawaii, in June 1993. In this paper some results of data analysis are presented and comparisons between Tenerife and Hilo measurements are shown. >

Conventional signal processing algorithms and detection criteria, optimised in presence of Gaussian noise, may degrade their performances in non-Gaussian environments. Higher Order Statistics (HOS) theory is a powerful means both for characterizing non-Gaussian noise and, then, for designing efficient and robust signal detectors. In particular, a method for detecting signals in additive independent non-Gaussian background noise have been investigated, analysed and compared with the bispectrum-based Hinich test and with a conventional spectrum-based detection criterion. In order to compare their respective performances, the different approaches have been applied on real underwater acoustic data, recording the passage of a target ship, in presence of background shipping traffic noise. >

The paper describes a nonlinear operator, based on frequency domain Kurtosis (FDK), that is able to distinguish between transients (impulses and unsteady harmonic components) and stationary sinusoidal signals in background Gaussian noise. For problems involving signal detection in burst noise, filtering by an FDK operator may improve detection results by reducing noise variance and amplifying narrow-band transient signals. To evaluate the FDK operator's efficiency, different processes are considered: impulsive noise and narrow-band interferences in background Gaussian noise and real electromagnetic non-Gaussian noise. The filter robustness is discussed.

Systems able to retrieve objects embedded in the sea bottom are of crucial importance for many different tasks, In this paper, an assessment of different advanced signal processing techniques for object detection classification is proposed, Such an assessment based on real data acquired by a parametric sonar, A detector based on the "classify-before-detect" paradigm has been developed that is well suited to exploit the available statistical and spectral a priori information. In other words, a statistical classifier has been employed to distinguish between two classes (i.e., target presence and target absence) exactly like detectors. Concerning classification, the focus has been placed on the exploitation of the object resonances and a neural network has been designed. As a first step the possibility for the network to be properly trained has been assessed, while as a second step the discrimination capability has been verified. The above methods have been tested with an experimental data set in which the echoes of a steel cylinder were embedded in real reverberation echoes, according to low signal-to-reverberation ratios.

This paper investigates the problem of providing reliable data about wave time-varying parameters by using three simple and low-cost acoustic altimeters installed on a buoy moored in the Mediterranean Sea. This research is performed in order to provide users with reliable and realtime information about sea conditions measured by a permanent installation in the open sea. Measures about sea conditions may be mainly used to safely operate navigation, to provide complementary information for weather forecasts, and to define the far field for the purpose of studying the behaviour of offshore structures with respect to the sea heave. The system provides reliable information about standard wave parameter (significant wave height, mean sea level, average period, spectral width, and so on). Moreover, wave motion direction can be estimate by correlating the measurements from the three devices. Results from a preliminary tests carried out by installing the described system on the sea bottom in shallow waters are presented.

This communication deals with the design of a TDEM (Time Domain Electromagnetic Measurement) system suitable for Martian subsoil investigation. An experiment, called MASTER (Mars subsurfAce Sounding by Time-domain Electromagnetic measuRements) is described. MASTER is expected to achieve the following main objectives: measure electrical conductivity profiles of Martian subsoil layers; identify Martian ground water/ice signatures; and perform passive measurements of the Martian electromagnetic environment. The particular application leads to the design of a system satisfying some specific requirements that, if not met, could compromise the quality performances of the data obtained. In the paper, a proposed configuration for the measurement system is described. Data acquisition and analysis strategy, required by the extreme environmental conditions, will be presented. This project, funded by the Italian Space Agency, has been proposed to fly aboard DEEDRI, the Italian Drill Payload for the Mars Surveyor Program 2003.

Publisher Summary This chapter deals with the analysis of the ELF signal, taking into account the Near-Field hypothesis conditions and the main problems related to this specific task. The chapter describes a non-linear adaptive pre-processing step, devoted to the preparation of the signal for a subsequent detection step through the deletion of random acquisition noise from SQUID magnetometers. To prove the validity of the proposed method, a spectral analysis of the processed signal is reported, where the features expected from the theoretical model can be easily detected even when analyzing a very short time interval. Finally, the contemporary exploitation of the two magnetometer systems by means of a data fusion process allows an increase in the information data set, while maintaining limited analysis time interval, effectively increasing the detection probability. By the method presented in the chapter, a precise analysis of the ELF signal and its temporal evolution can be performed.

The paper presents an optimization framework for quality assessment applied to a communication system. It is described as a network of processing modules, each of which characterized by a set of parameters influencing the quality of local processing and, as a consequence, the quality of the whole system results. In particular, the detection task is considered: the most significant sets of parameters influencing quality inside each of the system modules are selected and a quality-assessment criterion is developed in order to determine which values of these parameters allow one to reach optimized signal defection. A set of detection methods is examined and compared in order to establish their feasibility and performances by considering detection probability values as the selected parameters vary. The developed quality assessment framework was applied to a real case of detection of underwater acoustic signals in non Gaussian noise.