117,335 research outputs found
New Capabilities of TOPICA Code: Lower Hybrid Antennas and Full Toroidal Plasmas
No full textTOPICA (TOrino Polytechnic Ion Cyclotron Antenna) code is a numerical suite aimed at the performance prediction and analysis of plasma-facing antennas. It is capable of handling real-life 3D antenna geometries (with housing, Faraday screen, etc.) as well as a realistic plasma model, including measured density and temperature profiles. Thanks to the approach underlying the code (i.e. the formal splitting of the problem into two parts: the vacuum region around the antenna and the plasma region inside the toroidal chamber), TOPICA can be extended to deal with lower hybrid (waveguide grill) antennas, as well as toroidal plasma. TOPICA has been upgraded to simulate and design lower hybrid (waveguide grill) antennas. On the other hand, to include plasma curvature effects, TOPICA can adopt the plasma impedance matrix computed independently via the fully toroidal TORIC plasma code. This way TOPICA both provides more accurate antenna parameters and yields the proper input (i.e. the electric field in front of the Faraday shield) to self-consistently run TORIC in a subsequent plasma analysis. In this work an account for the new capabilities of TOPICA will be presente
Platelet-activating factor (PAF) receptor antagonists inhibit mitogen-induced human peripheral blood T-cell proliferation
No full textThe addition of L-652, 731 and L-653, 150, two synthetic PAF-specific receptor antagonists, to 72 hour cultures of phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear leukocytes (PBML) caused a dose-dependent inhibition of (3H)-thymidine incorporation into T-cells (IC50: 25 μM and 3.2 μM, respectively). This inhibition was not reversed by exogenous interleukin (IL)-1 and IL-2. PAF receptor antagonists did not affect the expression of IL-2 receptors (TAC-antigen) on T-cells. Exogenous PAF which by itself had no significant effect on PHA-stimulated PBML proliferation, only partially reversed the inhibition of proliferation caused by PAF receptor antagonists. These results may suggest the involvement of endogenously produced PAF in the regulation of immune reaction
A simulation approach for ICRF plasma thruster antennas
No full textIn the past twenty years plasma‐based propulsion systems have found increasing aerospace interest; although they were initially conceived as rockets for interplanetary missions, more recent advances in plasma‐based concepts have led to the identification of radio‐frequency (RF) generation and acceleration systems as capable of providing not only continuous thrust, but also controllable exhaust velocities, as required in maneuvering applications. The most interesting such studies for plasma propulsion are those focused on the possibility of coupling radio frequency power to plasma, exploiting the possibility of having very efficient devices to generate and heat the plasma, magnetically confining it in a trap in the heating region, so that ion can escape the magnetic trap only when they are energetic enough to be converted into direct out‐going flow which provides the thrust. The structure of this system is therefore based on of three stages where plasma is respectively generated, heated and expanded in a magnetic nozzle. The heating stage acts as an amplifier; here plasma is heated by the radio frequency waves by the process of ion cyclotron resonance. It has been developed and tested a numerical tool for the electromagnetic modeling of the ICRF antenna, of the RF booster unit of plasma thrusters, and of the RF‐plasma interactions. The latter is studied in the critical ICRF acceleration region by setting up a convenient Electromagnetic (EM) analytical and numerical model based on the Moment‐Method solution of a suitable set of integral equations. Solution of the relevant integral equation directly provides the electric surface current density induced on antenna conductors, but the ultimate quantity to be computed is the circuit characterization (e.g. admittance matrix) at the input ports
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
Intestinal Microbiota in IgE-mediated Cow’s Milk Allergy: microbial dysbiosis and possible modulation through probiotics
No full textObjectives and study: The aim of the study was to evaluate gut microbiota (GM) in infants with cow milk allergy (CMA) compared to food-sensitized and healthy infants. Furthermore, we investigated colonization, persistence and possible effects of a probiotic mixture (B. breve M-16V (BB), B. longum subsp. longum BB536 (BL) and B. longum subsp. infantis M-63 (BI)) in the GM of allergic infants.
Methods: We enrolled a total of 40 infants aged 10 to 15 months: 14 CMA patients (Group1); 12 positive IgE and negative food challenge patients (Group2); 14 healthy infants (Group3). For each patient, a stool sample was collected at enrolment (T 0 ). Group1 received probiotic twice per day (3.5×109 UFC/dose) for 30 days. Stool samples, collected at T 1 (7 days from probiotic intake), T2 (30 days from probiotic intake) and T 3 (after 60 day from probiotic discontinuation), were analysed
by real-time PCR. The GM profile of groups was characterized by 16S rRNA targeted metagenomics. Data were analysed by QIIME and IBM SPSS Statistic software.
Results: At baseline, BB and BL were present in the GM in the three Groups without significant differences. At T 0 , BI median concentration value was 0 in all the three groups, while after probiotics administration, RT-PCR analysis revealed a significant increase, from 0 to 6.4 x 10 1 molecules/l at T 1 (p=0.003) and 1.6 x 10 2 molecules/l at T 2 (p=0.005) with a decreased to 4.56 x 10 1 molecules/l at T 3. From basal microbiota comparison, we demonstrated that allergic patients clustered in Beta-
diversity analysis (PERMANOVA test (p=0.019)) and showed a peculiar phylogenetic relatedness.
At phylum level, Verrucomicrobia were higher in healthy group and gradually decreased from Group2 to Group1 (pFDR<0.05). Firmicutes resulted more abundant in Group2 and lower in Group3, while Group1 showed an intermediate level (pFDR<0.05).
At genus level, Haemophilus, Actinobacillus, Prevotella and Streptococcus resulted associated to allergy, with a significant increase (p<0.05) in Group1 and less in Group2 compared to Group3. Klebsiella showed a higher abundance in Group1 but not in Group2 compared to Group3.
Parabacteroides and Granulicatella were instead more abundant in Group3. During probiotic intake, there was an increase of Verrucomicrobia with a peak of abundance at T 2. Proteobacteria showed a gradually increase during probiotic intake and this increment was maintained also at T 3 . On the contrary, Actinobacteria decreased during the time-course, even if there was an increase form point T 1 to point T 2 . At genus level, probiotic intake determined an increase of Akkermansia, Prevotella and Ruminococcus. Actinomyces, Enterococcus, Streptococcus and Sutterella resulted instead diminished after probiotic intervention. Blautia increased during all the period of probiotic intake, until T 2 point, while at T 3 it started to decrease and showed a level of abundances lower than T 0 .
Conclusion: GM of CMA infants is different from that of sensitized and healthy infants and BI can colonize and persist in CMA GM. Probiotic administration provoked an increase of anti-inflammatory and a decrease of pro-inflammatory bacteria. In conclusions, early infancy is a window during which gut microbiota may shape food allergy outcomes in childhood and probiotics could be a rational way to modulate it
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Andrological evaluation and rehabilitative therapy of erectile function in patients with multiple sclerosis
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