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1.
Rev Sci Instrum ; 91(2): 023510, 2020 Feb 01.
Article in English | MEDLINE | ID: mdl-32113382

ABSTRACT

The requirements of ITER neutral beam injectors (1 MeV, 40 A negative deuterium ion current for 1 h) have never been simultaneously attained; therefore, a dedicated Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX (Padova, Italy). The NBTF includes two experiments: SPIDER (Source for the Production of Ions of Deuterium Extracted from Rf plasma), the full-scale prototype of the source of ITER injectors, with a 100 keV accelerator, to investigate and optimize the properties of the ion source; and MITICA, the full-scale prototype of the entire injector, devoted to the issues related to the accelerator, including voltage holding at low gas pressure. The present paper gives an account of the status of the procurements, of the timeline, and of the voltage holding tests and experiments for MITICA. As for SPIDER, the first year of operation is described, regarding the solution of some issues connected with the radiofrequency power, the source operation, and the characterization of the first negative ion beam.

2.
Rev Sci Instrum ; 89(10): 10J119, 2018 Oct.
Article in English | MEDLINE | ID: mdl-30399664

ABSTRACT

The measurements of the magnetic field in tokamaks such as ITER and DEMO will be challenging due to the long pulse duration, high neutron flux, and elevated temperatures. The long duration of the plasma pulse makes standard techniques, such as inductive coils, prone to errors. At the same time, the hostile environment, with repairs possible only on blanket exchange, if at all, requires a robust magnetic sensor. This contribution presents the final design of novel, steady-state, magnetic sensors for ITER. A poloidal array of 60 sensors mounted on the vacuum vessel outer shell contributes to the measurement of the plasma current, plasma-wall clearance, low-frequency MHD modes and will allow for crosscheck with the outer-vessel inductive coils. Each sensor hosts a pair of bismuth Hall probes, themselves an outcome of extensive R&D, including neutron irradiations (to 1023 n/m2), temperature cycling tests (73-473 K) and tests at high magnetic field (to 12 T). A significant effort has been devoted to optimize the sensor housing by design and prototyping. The production version features an indium-filled cell for in situ recalibration of the onboard thermocouple, vital for the interpretation of the Hall sensor measurement.

3.
BMC Genomics ; 17: 416, 2016 05 31.
Article in English | MEDLINE | ID: mdl-27245662

ABSTRACT

BACKGROUND: In wine grape production, management practices have been adopted to optimize grape and wine quality attributes by producing, or screening for, berries of smaller size. Fruit size and composition are influenced by numerous factors that include both internal (e.g. berry hormone metabolism) and external (e.g. environment and cultural practices) factors. Combined physiological, biochemical, and transcriptome analyses were performed to improve our current understanding of metabolic and transcriptional pathways related to berry ripening and composition in berries of different sizes. RESULTS: The comparison of berry physiology between small and large berries throughout development (from 31 to 121 days after anthesis, DAA) revealed significant differences in firmness, the rate of softening, and sugar accumulation at specific developmental stages. Small berries had significantly higher skin to berry weight ratio, lower number of seeds per berry, and higher anthocyanin concentration compared to large berries. RNA-sequencing analyses of berry skins at 47, 74, 103, and 121 DAA revealed a total of 3482 differentially expressed genes between small and large berries. Abscisic acid, auxin, and ethylene hormone pathway genes were differentially modulated between berry sizes. Fatty acid degradation and stilbenoid pathway genes were upregulated at 47 DAA while cell wall degrading and modification genes were downregulated at 74 DAA in small compared to large berries. In the late ripening stage, concerted upregulation of the general phenylpropanoid and stilbenoid pathway genes and downregulation of flavonoid pathway genes were observed in skins of small compared to large berries. Cis-regulatory element analysis of differentially expressed hormone, fruit texture, flavor, and aroma genes revealed an enrichment of specific regulatory motifs related to bZIP, bHLH, AP2/ERF, NAC, MYB, and MADS-box transcription factors. CONCLUSIONS: The study demonstrates that physiological and compositional differences between berries of different sizes parallel transcriptome changes that involve fruit texture, flavor, and aroma pathways. These results suggest that, in addition to direct effects brought about by differences in size, key aspects involved in the regulation of ripening likely contribute to different quality profiles between small and large berries.


Subject(s)
Energy Metabolism/genetics , Fruit/genetics , Fruit/metabolism , Gene Expression Regulation, Plant , Quantitative Trait, Heritable , Regulatory Sequences, Nucleic Acid , Transcriptome , Vitis/physiology , Gene Expression Profiling , Genetic Association Studies , Metabolic Networks and Pathways , Metabolomics/methods , Nucleotide Motifs , Plant Growth Regulators/metabolism , Signal Transduction
4.
Rev Sci Instrum ; 87(2): 02B309, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26932037

ABSTRACT

The megavolt ITER injector and concept advancement experiment is the prototype and the test bed of the ITER heating and current drive neutral beam injectors, currently in the final design phase, in view of the installation in Padova Research on Injector Megavolt Accelerated facility in Padova, Italy. The beam source is the key component of the system, as its goal is the generation of the 1 MeV accelerated beam of deuterium or hydrogen negative ions. This paper presents the highlights of the latest developments for the finalization of the MITICA beam source design, together with a description of the most recent analyses and R&D activities carried out in support of the design.

5.
J Theor Biol ; 359: 80-91, 2014 Oct 21.
Article in English | MEDLINE | ID: mdl-24907672

ABSTRACT

The cell-pressure-probe is a unique tool to study plant water relations in-situ. Inaccuracy in the estimation of cell volume (νo) is the major source of error in the calculation of both cell volumetric elastic modulus (ε) and cell hydraulic conductivity (Lp). Estimates of νo and Lp can be obtained with the pressure-clamp (PC) and pressure-relaxation (PR) methods. In theory, both methods should result in comparable νo and Lp estimates, but this has not been the case. In this study, the existing νo-theories for PC and PR methods were reviewed and clarified. A revised νo-theory was developed that is equally valid for the PC and PR methods. The revised theory was used to determine νo for two extreme scenarios of solute mixing between the experimental cell and sap in the pressure probe microcapillary. Using a fully automated cell-pressure-probe (ACPP) on leaf epidermal cells of Tradescantia virginiana, the validity of the revised theory was tested with experimental data. Calculated νo values from both methods were in the range of optically determined νo (=1.1-5.0nL) for T. virginiana. However, the PC method produced a systematically lower (21%) calculated νo compared to the PR method. Effects of solute mixing could only explain a potential error in calculated νo of <3%. For both methods, this discrepancy in νo was almost identical to the discrepancy in the measured ratio of ΔV/ΔP (total change in microcapillary sap volume versus corresponding change in cell turgor) of 19%, which is a fundamental parameter in calculating νo. It followed from the revised theory that the ratio of ΔV/ΔP was inversely related to the solute reflection coefficient. This highlighted that treating the experimental cell as an ideal osmometer in both methods is potentially not correct. Effects of non-ideal osmotic behavior by transmembrane solute movement may be minimized in the PR as compared to the PC method.


Subject(s)
Cell Size , Elastic Modulus/physiology , Models, Theoretical , Osmotic Pressure/physiology , Plant Cells/metabolism , Water/metabolism , Biological Transport/physiology , Movement/physiology , Plant Cells/physiology
6.
J Exp Bot ; 63(18): 6445-55, 2012 Nov.
Article in English | MEDLINE | ID: mdl-23136166

ABSTRACT

Vitis vinifera scions are commonly grafted onto rootstocks of other grape species to influence scion vigour and provide resistance to soil-borne pests and abiotic stress; however, the mechanisms by which rootstocks affect scion physiology remain unknown. This study characterized the hydraulic physiology of Vitis rootstocks that vary in vigour classification by investigating aquaporin (VvPIP) gene expression, fine-root hydraulic conductivity (Lp(r)), % aquaporin contribution to Lp(r), scion transpiration, and the size of root systems. Expression of several VvPIP genes was consistently greater in higher-vigour rootstocks under favourable growing conditions in a variety of media and in root tips compared to mature fine roots. Similar to VvPIP expression patterns, fine-root Lp(r) and % aquaporin contribution to Lp(r) determined under both osmotic (Lp(r)(Osm)) and hydrostatic (Lp(r)(Hyd)) pressure gradients were consistently greater in high-vigour rootstocks. Interestingly, the % aquaporin contribution was nearly identical for Lp(r)(Osm) and Lp(r)(Hyd) even though a hydrostatic gradient would induce a predominant flow across the apoplastic pathway. In common scion greenhouse experiments, leaf area-specific transpiration (E) and total leaf area increased with rootstock vigour and were positively correlated with fine-root Lp(r). These results suggest that increased canopy water demands for scion grafted onto high-vigour rootstocks are matched by adjustments in root-system hydraulic conductivity through the combination of fine-root Lp(r) and increased root surface area.


Subject(s)
Aquaporins/metabolism , Gene Expression Regulation, Plant , Plant Proteins/metabolism , Plant Roots/genetics , Plant Roots/metabolism , Vitis/metabolism , Aquaporins/genetics , Biological Transport , Osmosis , Plant Leaves/growth & development , Plant Leaves/metabolism , Plant Proteins/genetics , Plant Roots/growth & development , Polymerase Chain Reaction , Pressure , Vitis/genetics , Vitis/growth & development
7.
G Chir ; 29(1-2): 33-7, 2008.
Article in Italian | MEDLINE | ID: mdl-18252146

ABSTRACT

The Authors describe four cases of gastrointestinal stromal tumours (GIST) two of them were localized in the stomach, the others in the ileum. GIST are neoplasms of mesenchymal origin which develop inside the wall of the digestive tract. The most frequent site is the stomach, followed by the small bowel; less commonly these tumors can affect the oesophagus, the colon and the rectum. GIST originate from precursors of the interstitial cells of Cajal, which are localized in the gastro-intestinal wall and are involved in the regulation of the peristalsis. The treatment is surgical resection. For advanced disease there is a new interesting treatment based on the imatinib, a tyrosine kinase inhibitor.


Subject(s)
Digestive System Surgical Procedures , Gastrointestinal Stromal Tumors/surgery , Ileal Neoplasms/surgery , Stomach Neoplasms/surgery , Aged , Aged, 80 and over , Antineoplastic Agents/therapeutic use , Benzamides , Chemotherapy, Adjuvant , Coiled Bodies , Female , Gastrointestinal Stromal Tumors/drug therapy , Humans , Ileal Neoplasms/drug therapy , Imatinib Mesylate , Male , Middle Aged , Piperazines/therapeutic use , Protein-Tyrosine Kinases/antagonists & inhibitors , Pyrimidines/therapeutic use , Stomach Neoplasms/drug therapy
8.
J Exp Bot ; 58(15-16): 4037-46, 2007.
Article in English | MEDLINE | ID: mdl-18037677

ABSTRACT

Xylella fastidiosa (Xf) is a xylem-limited bacterium that lives as a harmless endophyte in most plant species but is pathogenic in several agriculturally important crops such as coffee, citrus, and grapevine (Vitis vinifera L.). In susceptible cultivars of grapevine, Xf infection results in leaf scorch, premature leaf senescence, and eventually vine death; a suite of symptoms collectively referred to as Pierce's disease. A qPCR assay was developed to determine bacterial concentrations in planta and these concentrations were related to the development of leaf-scorch symptoms. The concentration of Xf in leaves of experimental grapevines grown in the greenhouse was similar to the concentration of Xf in leaves of naturally infected plants in the field. The distribution of Xf was patchy within and among leaves. Some whole leaves exhibited severe leaf-scorch symptoms in the absence of high concentrations of Xf. Despite a highly sensitive assay and a range of Xf concentrations from 10(2) to 10(9) cells g(-1) fresh weight, no clear relationship between bacterial population and symptom development during Pierce's disease was revealed. Thus, high and localized concentrations of Xf are not necessary for the formation of leaf-scorch symptoms. The results are interpreted as being consistent with an atiology that involves a systemic plant response.


Subject(s)
Host-Pathogen Interactions/physiology , Plant Leaves/microbiology , Vitis/microbiology , Xylella/physiology , Plant Diseases , Polymerase Chain Reaction
9.
Ann Bot ; 97(5): 903-15, 2006 May.
Article in English | MEDLINE | ID: mdl-16390845

ABSTRACT

BACKGROUND AND AIMS: The basic regulatory mechanisms that control lateral root (LR) initiation are still poorly understood. An attempt is made to characterize the pattern and timing of LR initiation, to define a developmental window in which LR initiation takes place and to address the question of whether LR initiation is predictable. METHODS: The spatial patterning of LRs and LR primordia (LRPs) on cleared root preparations were characterized. New measures of LR and LRP densities (number of LRs and/or LRPs divided by the length of the root portions where they are present) were introduced and illustrate the shortcomings of the more customarily used measure through a comparative analysis of the mutant aux1-7. The enhancer trap line J0121 was used to monitor LR initiation in time-lapse experiments and a plasmolysis-based method was developed to determine the number of pericycle cells between successive LRPs. KEY RESULTS: LRP initiation occurred strictly acropetally and no de novo initiation events were found between already developed LRs or LRPs. However, LRPs did not become LRs in a similar pattern. The longitudinal spacing of lateral organs was variable and the distance between lateral organs was proportional to the number of cells and the time between initiations of successive LRPs. There was a strong tendency towards alternation in LR initiation between the two pericycle cell files adjacent to the protoxylem poles. LR density increased with time due to the emergence of slowly developing LRPs and appears to be unique for individual Arabidopsis accessions. CONCLUSIONS: In Arabidopsis there is a narrow developmental window for LR initiation, and no specific cell-count or distance-measuring mechanisms have been found that determine the site of successive initiation events. Nevertheless, the branching density and lateral organ density (density of LRs and LRPs) are accession-specific, and based on the latter density the average distance between successive LRs can be predicted.


Subject(s)
Arabidopsis/growth & development , Plant Roots/growth & development , Arabidopsis/anatomy & histology , Arabidopsis/genetics , Plant Roots/anatomy & histology , Plants, Genetically Modified/growth & development , Time Factors
10.
Alerg. inmunol. clin ; 23(3/4): 72-75, 2005.
Article in Spanish | LILACS | ID: lil-429483

ABSTRACT

La criptococosis es la infeccion micotica grave mas comun en pacientes infectados por el virus de inmunodeficiencia humana (HIV) (1), siendo el SIDA el factor predisponente en el 80-90 por ciento de los casos y suele ocurrir con recuentos de CD4 menores a 200/mm3 (2). Presentamos un caso de criptococosis en un paciente con serologia negativa para HIV, en el cual encotramos una hipogammaglubulinemia, que podria corresponder a una Inmunodeficiencia Comun Variable


Subject(s)
HIV
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