Assessing the efficiency of the Italian aquaculture firms     

Maria Bonaventura Forleo  Luca Romagnoli  Rosa Maria Fanelli  Nadia Palmieri  Angela Di Nocera 《Aquaculture Economics & Management (Blackwell Science)》2013,17(4):382-409

Abstract

The study investigates the efficiency of a sample of Italian aquaculture firms according to their legal status, size, and location. An efficiency analysis was conducted for a sample of 160 units using an output-oriented Data Envelopment Analysis. The average value of the efficiency scores reveals that it should be possible to significantly increase firm performance. The most inefficient farms are cooperatives, southern farms, and the smallest farms. The weight of efficient units is as follows: 34% of the cooperatives and 26% of the limited liability companies; 26% of units located in Northern-Central regions and 34% of those placed in Southern areas; 47% of the big and 23% of the small firms. Among subgroups of units, the only significant difference in the average efficiency score is related to the firm size. The sensitivity of the results to methodological choices reveals that the variable return to scale hypothesis fits the data better than the constant returns to scale and that bootstrapping while changing the value of the scores does not change findings in terms of size, location, and legal status. Actions which remove obstacles and increase firm size are the most obvious ways to improve the efficiency and competitiveness of the sector.  相似文献   

Genetic diversity and distinctiveness in tomato (Solanum lycopersicum L.) landraces: The Italian case study of ‘A pera Abruzzese’     

Andrea Mazzucato  Nadia Ficcadenti  Marcello Caioni  Pietro Mosconi  Enrico Piccinini  Venkata Rami Reddy Sanampudi  Sara Sestili  Valentino Ferrari 《Scientia Horticulturae》2010

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Characterization of Salmonella Typhimurium isolates associated with septicemia in swine     

Nadia Bergeron  Jonathan Corriveau  Ann Letellier  France Daigle  Sylvain Quessy 《Canadian journal of veterinary research》2010,74(1):11-17

Salmonella Typhimurium is frequently isolated from pigs and may also cause enteric disease in humans. In this study, 33 isolates of S. Typhimurium associated with septicemia in swine (CS) were compared to 33 isolates recovered from healthy animals at slaughter (WCS). The isolates were characterized using phenotyping and genotyping methods. For each isolate, the phage type, antimicrobial resistance, and pulsed-field gel electrophoresis (PFGE) DNA profiles were determined. In addition, the protein profiles of each isolate grown in different conditions were studied by Coomassie Blue-stained sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot. Various phage types were identified. The phage type PT 104 represented 36.4% of all isolates from septicemic pigs. Resistance to as many as 12 antimicrobial agents, including some natural resistances, was found in isolates from CS and WCS. Many genetic profiles were identified among the PT 104 phage types. Although it was not possible to associate one particular protein with septicemic isolates, several highly immunogenic proteins, present in all virulent isolates and in most isolates from clinically healthy animals, were identified. These results indicated that strains associated with septicemia belong to various genetic lineages that can also be recovered from asymptomatic animals at the time of slaughter.  相似文献   

Morphological and molecular identification of potato and cereal cyst nematode isolates from Algeria and their phylogenetic relationships with other populations from distant theirgeographical areas     

Nadia?Tirchi  Alberto?Troccoli  Elena?Fanelli  Aissa?Mokabli  Fazia?Mouhouche  Francesca?De?LucaEmail author 《European journal of plant pathology / European Foundation for Plant Pathology》2016,146(4):861-880

A nematode survey conducted in 2013 in Algeria, revealed that potato cyst nematodes (PCN) and cereal cyst nematodes (CCN) are widely distributed in several potato and cereal growing regions of the country. Sixteen PCN populations from five localities and five CCN populations from four of these localities were collected and characterized at the morphological and molecular levels. The PCN populations were identified as Globodera rostochiensis and G. pallida occurring separately or in mixed populations. Two species of CCN were detected. Heterodera avenae was found in four localities, whereas H. hordecalis only in one locality in association with H. avenae. The morphological and morphometric identification of PCN and CCN was confirmed by diagnostic ITS-RFLP profiles and sequencing. Phylogenetic analysis of the ITS, D2-D3 expansion domains of the 28S rRNA gene and 18S rRNA gene was made for PCN and CCN populations. Globodera pallida and G. rostochiensis from Algeria show great similarity with European and South American populations. Because of the high divergence among Algerian populations of G. pallida and G. rostochiensis it can be assumed that they were multi-introduced in Algeria. The most divergent population of G. pallida, that formed a well-separated group with some populations from Chile and Peru, suggests a later or independent introduction of this population into Algeria. Heterodera avenae and H. hordecalis formed a well-supported cluster with the corresponding populations.  相似文献   

How to Assess Temporal Changes of Point and Diffuse Contamination in a Rural Karstic Watershed? Relevance of Suspended Particulate Matter (SPM) for Efficient Monitoring     

Axelle Chiffre  François Degiorgi  Nadia Morin-Crini  Audrey Bolard  Etienne Chanez  Pierre-Marie Badot 《Water, air, and soil pollution》2016,227(10):384

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Toxicity of some juvenile hormone-active compounds forspodoptera littoralis boisd. larvae     

K. R. S. Ascher  Nadia E. Nemny 《Phytoparasitica》1974,2(1):41-44

Six juvenile hormone analogues, compounds 6–9550, 8–4314, and 20–3600 of Dr. R. Maag Ltd., Switzerland, and compounds ZR-512, ZR-515 and ZR-619 of Zoecon Corp., U.S.A., were tested against big and medium-size larvae ofS. littoralis Boisd. by topical application. Compounds 6–9550 and 8–4314 were slightly active against big larvae and inactive against medium-size larvae; ZR-512 was moderately active against big and inactive against medium-size larvae. The other three compounds caused 90% mortality in big larvae: 20–3600 at 20μg/larva and ZR-515 and ZR-619 at 5μg/larva. ZR-512 and ZR-619 were less toxic for medium-size larvae than for big larvae, whereas 20–3600 was about equitoxic for larvae of both sizes  相似文献   

The ovicidal effect of ph 60-40 [l-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea] inspodoptera littoralis boisd     

K. R. S. Ascher  Nadia E. Nemny 《Phytoparasitica》1974,2(2):131-133

PH 60-40 is of very high toxicity toSpodoptera littoralis eggs in laboratory experiments; 100% kill was obtained by dipping young eggs in a 0.000 025% a.i. dilution in water of a 5% liquid formulation of the compound.  相似文献   

Molecular differentiation of Mycobacterium bovis isolates. Review of main techniques and applications     

Haddad N  Masselot M  Durand B 《Research in veterinary science》2004,76(1):1-18

Until recently, none of the Mycobacterium bovis typing techniques permitted a satisfactory differentiation of isolates. During the last 10 years, the genome of pathogenic mycobacteria has been extensively studied, and phylogenetic analyses have shown that all (except Mycobacterium avium) belong to a single genetic species: the Mycobacterium tuberculosis complex. This increase in knowledge about the genome of these bacteria has lead to the discovery of molecular markers that allow us to differentiate isolates. Because of the phylogenetic proximity of the strains, even if most of these markers have been discovered in M. tuberculosis, they could be successfully adapted to the other bacteria of the M. tuberculosis complex, especially M. bovis. The most common markers in use today are the IS6110 insertion sequence, the direct repeat (DR) region, the poly(GC) rich (PGRS) sequences and the variable number tandem repeats (VNTR) sequences. The corresponding typing techniques are briefly described, and current knowledge of polymorphism and marker stability is detailed. If molecular markers are to offer wide perspectives for field studies, these two characteristics (polymorphism and stability) must be taken into account when choosing the marker(s) used in a study. In this context, examples of the application of molecular typing techniques for M. bovis are reviewed, on the one hand with epidemiological studies for which the major problem is the comparison between isolates and, on the other, with more general studies about the population genetics of M. bovis in a given country, and about its history and its phylogeny.  相似文献   

Multiple pathogenic factors influence aphid transmission of cauliflower mosaic virus from infected plants     

Nadia S. Al-Kaff  David S. Turner  Simon N. Covey 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(1):65-71

Aphid transmission of cauliflower mosaic virus (CaMV) is mediated by a polypeptide (P18) encoded by the viral gene II. We have investigated the factors which influence acquisition by aphids of CaMV variants from infected plants. Aphid non-transmissible (AT^-) CaMV isolates with a full-length gene II sequence share two amino acid changes, gly to arg at position 94 and ile to val at 105, relative to wild type transmissible (AT⁺) isolates. We have mutated the gly to arg at position 94 in the AT⁺ isolate Cabb B-JI which then exhibited the AT^- phenotype as predicted. However, replacement of a DNA fragment in Cabb B-JI with one containing the gly to arg change from the AT^- isolate Campbell to produce hybrid pBJIC1 resulted in a change in symptom phenotype as well as in aphid transmissibility. pBJIC1 also showed characteristics of partial transmissibility related to the stage of infection when it was tested. The level of P18 was measured in plants and showed that recombinants based upon the Campbell (AT^-) genome accumulated P18 later than those based upon the Cabb B-JI genome (AT⁺). However, the Campbell P18 or recombinant proteins like it, were still not able to mediate transmission even when the P18 level in plants was relatively high and by employing large numbers of aphids. We conclude that aphid transmissibility of CaMV is influenced by multiple factors including P18 levels, inherent functionality of the protein, pathogenic characters of the infecting strain, and the number of aphids used to test transmissibility.  相似文献   

Diflubenzuron delays the onset of mortality caused by sodium fluosilicate and fluoroacetamide in the housefly     

K. R. S. Ascher  Nadia E. Nemny 《Phytoparasitica》1980,8(3):217-219

The toxic effect of sucrose-containing Na₂SiF₆ solutions fed to houseflies is delayed when diflubenzuron (DFB) is added to the solutions. A similar, though less pronounced effect is exerted by DFB on fluoroacetamide toxicity.  相似文献