1,372 research outputs found

    Three dimensional imaging of short pulses

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    We exploit a slightly noncollinear second-harmonic cross-correlation scheme to map the 3D space-time intensity distribution of an unknown complex-shaped ultrashort optical pulse. We show the capability of the technique to reconstruct both the amplitude and the phase of the field through the coherence of the nonlinear interaction down to a resolution of 10 ÎĽ\mum in space and 200 fs in time. This implies that the concept of second-harmonic holography can be employed down to the sub-ps time scale, and used to discuss the features of the technique in terms of the reconstructed fields.Comment: 16 pages, 6 figure

    A geobotanical survey on acidophilous grasslands in the Abruzzo, Lazio and Molise National Park (Central Italy)

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    The acidophilous grasslands of the south-eastern part of the Abruzzo, Lazio and Molise National Park was studied by the phytosociological method and analyzed from a synecological viewpoint with the help of soil analysis. Four clusters of relevés resulted from the numerical classification. Syntaxonomically they were ascribed to the following associations: Poo violaceae-Nardetum strictae, Potentillo rigoanae-Festucetum paniculatae, Nardo strictae-Brachypodietum genuensis and Potentillo rigoanae-Brachypodietum genuensis. Since the original proposal of all the syntaxa identified in the present study were affected by nomenclatural mistakes, they were corrected in accordance with the rules of ICPN. The occurrence of Anthoxanto-Brachypodietum in central Apennines, is excluded since this association falls in syntaxonomical synonymy with Potentillo-Brachypodietum. The synecological analysis proved that the distribution of the different communities identified within the study area to be correlated with topographic, geomorphological and soil factors. Among these latter, the ratio H+/basic cations, pH behave as the most influencing parameters in the distribution of the communities identified

    Research Directions in the Study of Gaming-Related Escapism: a Commentary to Melodia, Canale, and Griffiths (2020)

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    Escapism motivations and related processes (e.g., avoidance, dissociation, relaxation, and emotion dysregulation) have been identified as risk factors for problematic gaming. However, the escapism construct has often been poorly conceptualized and operationalized in assessment instruments. In their systematic review, Melodia et al. (2020) proposed that conceptualizing escapism as an avoidant coping strategy could provide a sound basis for further study of problematic gaming. In this commentary, we critically examine some terminological and conceptual issues in relation to escapism to guide future research

    Reactions to treatment debriefing among the participants of a placebo controlled trial

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    BACKGROUND: A significant proportion of trial participants respond to placebos for a variety of conditions. Despite the common conduct of these trials and the strong emphasis placed on informed consent, very little is known about informing participants about their individual treatment allocation at trial closure. This study aims to address this gap in the literature by exploring treatment beliefs and reactions to feedback about treatment allocation in the participants of a placebo-controlled randomized clinical trial (RCT). METHODS: Survey of trial participants using a semi-structured questionnaire including close and open-ended questions administered as telephone interviews and postal questionnaires. Trial participants were enrolled in a double-blind placebo-controlled RCT evaluating the effectiveness of corticosteroid for heel pain (ISRCTN36539116). The trial had closed and participants remained blind to treatment allocation. We assessed treatment expectations, the percentage of participants who wanted to be informed about their treatment allocation, their ability to guess and reactions to debriefing. RESULTS: Forty-six (73%) contactable participants responded to our survey. Forty-two were eligible (four participants with bilateral disease were excluded as they had received both treatments). Most (79%) participants did not have any expectations prior to receiving treatment, but many 'hoped' that something would help. Reasons for not having high expectations included the experimental nature of their care and possibility that they may get a placebo. Participants were hopeful because their pain was so severe and because they trusted the staff and services. Most (83%) wanted to be informed about their treatment allocation and study results. Over half (55%) said they could not guess which treatment they had been randomized to, and many of those who attempted a guess were incorrect. Reactions to treatment debriefing were generally positive, including in placebo responders. CONCLUSION: Our study suggests that most trial participants want to be informed about their treatment allocation and trial results. Further research is required to develop measure of hope and expectancy and to rigorously evaluate the effects of debriefing prospectively

    Wind-aided flame spread under oblique forced flow

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    he wind-aided flame spread process along a solid fuel rod under oblique forced flow is analyzed in absence of gravity or when the forced flow dominates the gravity-induced flow. The transverse velocity is large enough to ensure that mixing of the fuel vapors and air occurs in a thin boundary layer surrounding the fuel rod and we can use the boundary layer approximation to describe the gas-phase chemical reaction and downwind flame spread process. A global, second-order, Arrhenius expression is employed to describe the gas-phase reaction, while the solid surface gasification reaction is modeled in terms of a constant pyrolysis temperature. The solid is heated by the hot gases convected from the flame by the axial component of the velocity in the direction of the flame spread. The solid will be considered thermally thick, assuming the thickness of the heated layer in the solid to be small compared with the rod radius. The analysis determines the flame spread velocity and the flow structure in the flame front region. The analysis also shows that flame spread is not possible at large flow velocities due to finite rate effects, while at low velocities the gas-phase reaction is diffusion-controlled. By including radiation losses from the surface a flame spread limit, at low velocities, is also found in the present analysis. The wind-aided flame spread process along a solid fuel rod under oblique forced flow is analyzed in absence of gravity or when the forced flow dominates the gravity-induced flow. The transverse velocity is large enough to ensure that mixing of the fuel vapors and air occurs in a thin boundary layer surrounding the fuel rod and we can use the boundary layer approximation to describe the gas-phase chemical reaction and downwind flame spread process. A global, second-order, Arrhenius expression is employed to describe the gas-phase reaction, while the solid surface gasification reaction is modeled in terms of a constant pyrolysis temperature. The solid is heated by the hot gases convected from the flame by the axial component of the velocity in the direction of the flame spread. The solid will be considered thermally thick, assuming the thickness of the heated layer in the solid to be small compared with the rod radius. The analysis determines the flame spread velocity and the flow structure in the flame front region. The analysis also shows that flame spread is not possible at large flow velocities due to finite rate effects, while at low velocities the gas-phase reaction is diffusion-controlled. By including radiation losses from the surface a flame spread limit, at low velocities, is also found in the present analysis

    Dark Matter detection via lepton cosmic rays

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    Recent observations of lepton cosmic rays, coming from the PAMELA and FERMI experiments, have pushed our understanding of the interstellar medium and cosmic rays sources to unprecedented levels. The imprint of dark matter on lepton cosmic rays is the most exciting explanation of both PAMELA's positron excess and FERMI's total flux of electrons. Alternatively, supernovae are astrophysical objects with the same potential to explain these observations. In this work, we present an updated study of the astrophysical sources of lepton cosmic rays and the possible trace of a dark matter signal on the positron excess and total flux of electrons.Comment: 6 pages and 3 figures. Proceedings for PASCOS 2010, Valencia, Spai

    Fine characterization of immunological mechanisms mediated by the major allergens of Parietaria judaica and hypoallergenic hybrid, rPjEDcys

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    Purpose: Allergy is a hypersensitivity disease IgE-mediated, affecting more than 25% of the population. The symptoms of IgE-mediated allergies reactions can be transiently ameliorated pharmacologically, but the only curative treatment of allergies is Allergen-Specific Immunotherapy (SIT). Recombinant hypoallergenic allergen derivatives with reduced allergenic activity have been engineered to reduce side effects during SIT. Parietaria judaica (Pj) pollen contains two major allergens belonging to the family of Lipid Tranfer Proteins (Par j 1 and Par j 2). By means of DNA recombinant technology, a hybrid hypoallergenic (PjEDcys), expressing disulphide bond variants of Par j 1 and Par j 2, was generated. The aim of this research project is to study the immunological mechanisms activated by the major allergens of Parietaria judaica, Par j 1 and Par j 2, and hypoallergenic hybrid rPjEDcys. Moreover, the project I am involved is trying to address the question whether this engineered hypoallergenic derivative can be a potential products for safer Allergen Specific Immunotherapy (SIT). Methods: Par j 1, Par j 2 and PjEDcys were produced as recombinant proteins. Human Peripheral Blood Mononuclear Cell (PBMC) from P. judaica allergic patients were stimulated in vitro with wild-type recombinant allergens and hybrid. PBMC proliferation assay, cytokine secretion assay, magnetic cell sorting of different subset of regulatory T cells, multiparametric flow cytometric analysis and molecular characterization using Real Time-PCR on sorted cells allow to study the biological properties of wild-type recombinant allergens and hybrid hypoallergenic derivate. Results: In vitro analysis suggested that PjEDcys have a reduced allergenity and maintained T cells reactivity. PBMC of P. judaica allergic patients stimulated in vitro with the hybrid and the wild-type recombinant allergens scored a percentage of proliferating CD4+ and CD56+ cell higher than unstimulated sample. Consistent with these data, cytokine secretion assay on CD4+ cells demonstrated that PBMC stimulation with rPjEDcys showed a percentage of IL-5 and IL-13 secreting T CD4+ cells lower than the wild-type allergens. Both rPjEDcys and wild-type stimulation promote the secretion of IFN- \u3b3 and IL-10 by T CD4+ cells. Finally whit the aim to study which subset of regulatory cells respond to wild-tipe allergens and hypoallergenic hybrid new experiment are setting. Discussion: In this experimental setting, the use of the major allergens of Pj and the hybrid polypeptides, rPjEDcys allows me to study the immunological mechanisms activated by the two different antigen stimulation and to investigate differences between the wild-type allergen and the hypoallergenic mutant rPjEDcys. Our data showed that CD4+ cells are clearly the predominant cell population proliferating in response to mixture of Par j 1 and Par j 2 allergens. The hypoallergenic derivate rPjEDcys retain the ability to stimulate CD4+ cells proliferation like the mixture of allergens (rPar j 1 and rPar j 2). Moreover these results highlighted a particular interesting datum; the mixture of allergens and the rPjEDcys hybrid showed the ability to stimulate an innate immune response, inducing CD56+ cells proliferative response. Cytokine secretion assay demonstrate that rPjEDcys reduce the secretion of IL-5 and IL-13, Th2 cytokines with a critical role in the development of allergy, compared to wild-type allergens. This may reflect the different biological function exerted by rPjEDcys. Conclusion: Collectivelly, our findings demonstrate that PjEDcys show a reduced allergenicity but maintained its immunogenicity and maybe it is also capable to regulate and redirect the immune response. These results suggest that PjEDcys represent a useful approach for immunotherapy of allergic disease

    Examining bi-directionality between Fear of Missing Out and problematic smartphone use. A two-wave panel study among adolescents

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    Background: In recent years, the Fear of Missing Out (FoMO) construct has been the object of growing attention in digital technology research with previous studies finding support for the relationship between FoMO and problematic smartphone use (PSU) among adolescents and young adults. However, no previous studies clarified the causal link between FoMO and PSU using a longitudinal design. Methods: An auto-regressive, cross-lagged panel design was tested by using a longitudinal dataset with two waves of data collection (T0 and T1, one year apart). Participants included two hundred and forty-two adolescents (109 males and 133 females), with a mean age of 14.16 years, who filled out the Fear of Missing Out scale (FoMOs) and the Smartphone Addiction Scale (SAS). Moreover, participants filled out the Difficulties in Emotion Regulation Scale (DERS), at the first time-point of data collection. Results: The findings of the study show that FoMO (both FoMO-Fear and FoMO-Control subscales) and PSU are positively related at both time-points (i.e. at a cross-sectional level). However no cross-lagged associations between them were longitudinally supported. Females and older adolescents show higher FoMO-Fear at T1. Conclusions: The findings of the present study suggest caution when causal links between FoMO and PSU are inferred

    Study of uptake mechanisms of halloysite nanotubes in different cell lines

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    Purpose: Halloysite nanotubes (HNTs) are a natural aluminosilicate clay with a chemical formula of Al2Si2O5(OH)4Ă—nH2O and a hollow tubular structure. Due to their peculiar structure, HNTs can play an important role as a drug carrier system. Currently, the mechanism by which HNTs are internalized into living cells, and what is the transport pathway, is still unclear. Therefore, this study aimed at establishing the in vitro mechanism by which halloysite nanotubes could be internalized, using phagocytic and non-phagocytic cell lines as models. Methods: The HNT/CURBO hybrid system, where a fluorescent probe (CURBO) is confined in the HNT lumen, has been used as a model to study the transport pathway mechanisms of HNTs. The cytocompatibility of HNT/CURBO on cell lines model was investigated by MTS assay. In order to identify the internalization pathway involved in the cellular uptake, we performed various endocytosis-inhibiting studies, and we used fluorescence microscopy to verify the nanomaterial internalization by cells. We evaluated the haemolytic effect of HNT/CURBO placed in contact with human red blood cells (HRBCs), by reading the absorbance value of the supernatant at 570 nm. Results: The HNT/CURBO is highly biocompatible and does not have an appreciable haemolytic effect. The results of the inhibition tests have shown that the internalization process of nanotubes occurs in an energy-dependent manner in both the investigated cell lines, although they have different characteristics. In particular, in non-phagocytic cells, clathrin-dependent and independent endocytosis are involved. In phagocytic cells, in addition to phagocytosis and clathrin-dependent endocytosis, microtubules also participate in the halloysite cellular trafficking. Upon internalization by cells, HNT/CURBO is localized in the cytoplasmic area, particularly in the perinuclear region. Conclusion: Understanding the cellular transport pathways of HNTs can help in the rational design of novel drug delivery systems and can be of great value for their applications in biotechnology
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