590 research outputs found

    Oral mucosal melanoma: a malignant trap

    Get PDF
    Oral mucosal melanomas are highly malignant tumors. The 'chameleonic' presentation of a mainly asymptomatic condition, the rarity of these lesions, the poor prognosis and the necessity of a highly specialized treatment are factors that should be seriously considered by the involved health provider. We present the case of a 75-year-old man who was referred to the Ear, Nose and Throat department. His symptoms were voice alteration and saliva drooling, progressively worsening during the last few weeks. The absence of pain was the reason for the delay of seeking medical care. The diagnosis was an oversized oral melanoma. This is an example of how the time of diagnosis and the evolution of a disease could be seriously influenced by patient's behavior. Melanomas arising from oral mucosa have poor prognosis unless they are discovered and treated early. The vigilance of the physicians is necessary to have success in this difficult task

    Mobility of Knowledge and Local Innovation Activity

    Get PDF
    This paper studies the diffusion of knowledge and its consequences for local innovation production. In a common framework, we analyze the geographic reach of different channels of knowledge flows that thus far have been studied separately in the literature. To jointly estimate these flows, we develop and apply novel econometric techniques appropriate to the nature of the data. We find that geographic along with technological proximity to be more essential to the operation of market than to non-market channels of knowledge flows. External accessible disembodied knowledge has a strong positive effect on local innovation production as large as that of homegrown knowledge

    Mobility of Knowledge and Local Innovation Activity

    Get PDF
    This paper studies the diffusion of knowledge and its consequences for local innovation production. In a common framework, we analyze the geographic reach of different channels of knowledge flows that thus far have been studied separately in the literature. To jointly estimate these flows, we develop and apply novel econometric techniques appropriate to the nature of the data. We find that geographic along with technological proximity to be more essential to the operation of market than to non-market channels of knowledge flows. External accessible disembodied knowledge has a strong positive effect on local innovation production as large as that of homegrown knowledge

    Identification and differential expression dynamics of peach small GTPases encoding genes during fruit development and ripening

    Get PDF
    The function of monomeric GTPases of the RAS superfamily in fruit development and ripening has been partially characterized. Here the identification of peach (Prunus persica) small GTPases of the RAS superfamily expressed in fruit and the characterization of their expression profiles during fruit development are described. Extensive searches on expressed sequence tag (EST) databases led to the selection of a total of 24 genes from peach encoding proteins with significant similarity to Arabidopsis small GTPases. Sequence similarity analyses and identification of conserved motifs, diagnostic of specific RAS families and subfamilies, enabled bona fide assignment of fourteen PpRAB, seven PpARF/ARL/SAR, two PpROP and one PpRAN GTPases. Transcriptional expression profiles of peach monomeric GTPases, analysed by real-time quantitative reverse transcription-PCR, were obtained for mesocarp samples, collected in two consecutive years. Reproducible patterns of expression could be identified for five peach RAB-encoding genes (PpRABA1-1, PpRABA2, PpRABD2-1, PpRABD2-2, and PpRABC2), two ARFs (PpARFA1-1 and PpARLB1), and two ROPs (PpROP3 and PpROP4). Interestingly, the transient transcriptional up-regulation of PpARF genes and of PpRAB genes of the A and D clades, putatively controlling the exocytic delivery of cell wall components and modifying enzymes, appeared to coincide with peaks of growth speed and sugar accumulation and with the final phases of ripening. To our knowledge, this is the first description of the co-ordinated differential expression of a set of genes encoding small GTPases of the ARF and RAB families which takes place during key moments of fruit development and maturation

    Preparation of hydrogen, fluorine and chlorine doped and co-doped titanium dioxide photocatalysts: a theoretical and experimental approach

    Get PDF
    Titanium dioxide (TiO2) has a strong photocatalytic activity in the ultra-violet part of the spectrum combined with excellent chemical stability and abundance. However, its photocatalytic efficiency is prohibited by limited absorption within the visible range derived from its wide band gap value and the presence of charge trapping states located at the band edges, which act as electron-hole recombination centers. Herein, we modify the band gap and improve the optical properties of TiO2via co-doping with hydrogen and halogen. The present density functional theory (DFT) calculations indicate that hydrogen is incorporated in interstitial sites while fluorine and chlorine can be inserted both as interstitial and oxygen substitutional defects. To investigate the synergy of dopants in TiO2 experimental characterization techniques such as Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray and ultra-violet photoelectron spectroscopy (XPS/UPS), UV-Vis absorption and scanning electron microscopy (SEM) measurements, have been conducted. The observations suggest that the oxide’s band gap is reduced upon halogen doping, particularly for chlorine, making this material promising for energy harvesting devices. The studies on hydrogen production ability of these materials support the enhanced hydrogen production rates for chlorine doped (Cl:TiO2) and hydrogenated (H:TiO2) oxides compared to the pristine TiO2 reference

    T1 at 1.5T and 3T compared with conventional T2* at 1.5T for cardiac siderosis

    Get PDF
    Background: Myocardial black blood (BB) T2* relaxometry at 1.5T provides robust, reproducible and calibrated non-invasive assessment of cardiac iron burden. In vitro data has shown that like T2*, novel native Modified Look-Locker Inversion recovery (MOLLI) T1 shortens with increasing tissue iron. The relative merits of T1 and T2* are largely unexplored. We compared the established 1.5T BB T2* technique against native T1 values at 1.5T and 3T in iron overload patients and in normal volunteers. Methods: A total of 73 subjects (42 male) were recruited, comprising 20 healthy volunteers (controls) and 53 patients (thalassemia major 22, sickle cell disease 9, hereditary hemochromatosis 9, other iron overload conditions 13). Single mid-ventricular short axis slices were acquired for BB T2* at 1.5T and MOLLI T1 quantification at 1.5T and 3T. Results: In healthy volunteers, median T1 was 1014 ms (full range 939–1059 ms) at 1.5T and modestly increased to 1165ms (full range 1056–1224 ms) at 3T. All patients with significant cardiac iron overload (1.5T T2* values <20 ms) had T1 values <939 ms at 1.5T, and <1056 ms at 3T. Associations between T2* and T1 were found to be moderate with y =377 · x0.282 at 1.5T (R2 = 0.717), and y =406 · x0.294 at 3T (R2 = 0.715). Measures of reproducibility of T1 appeared superior to T2*. Conclusions: T1 mapping at 1.5T and at 3T can identify individuals with significant iron loading as defined by the current gold standard T2* at 1.5T. However, there is significant scatter between results which may reflect measurement error, but it is also possible that T1 interacts with T2*, or is differentially sensitive to aspects of iron chemistry or other biology. Hurdles to clinical implementation of T1 include the lack of calibration against human myocardial iron concentration, no demonstrated relation to cardiac outcomes, and variation in absolute T1 values between scanners, which makes inter-centre comparisons difficult. The relative merits of T1 at 3T versus T2* at 3T require further consideration

    Anomaly detection search for new resonances decaying into a Higgs boson and a generic new particle X in hadronic final states using Formula Presented pp collisions with the ATLAS detector

    Get PDF
    A search is presented for a heavy resonance Formula Presented decaying into a Standard Model Higgs boson Formula Presented and a new particle Formula Presented in a fully hadronic final state. The full Large Hadron Collider run 2 dataset of proton-proton collisions at Formula Presented collected by the ATLAS detector from 2015 to 2018 is used and corresponds to an integrated luminosity of Formula Presented. The search targets the high Formula Presented-mass region, where the Formula Presented and Formula Presented have a significant Lorentz boost in the laboratory frame. A novel application of anomaly detection is used to define a general signal region, where events are selected solely because of their incompatibility with a learned background-only model. It is constructed using a jet-level tagger for signal-model-independent selection of the boosted Formula Presented particle, representing the first application of fully unsupervised machine learning to an ATLAS analysis. Two additional signal regions are implemented to target a benchmark Formula Presented decay into two quarks, covering topologies where the Formula Presented is reconstructed as either a single large-radius jet or two small-radius jets. The analysis selects Higgs boson decays into Formula Presented, and a dedicated neural-network-based tagger provides sensitivity to the boosted heavy-flavor topology. No significant excess of data over the expected background is observed, and the results are presented as upper limits on the production cross section Formula Presented) for signals with Formula Presented between 1.5 and 6 TeV and Formula Presented between 65 and 3000 GeV. A search is presented for a heavy resonance Y decaying into a Standard Model Higgs boson H and a new particle X in a fully hadronic final state. The full Large Hadron Collider run 2 dataset of proton-proton collisions at √ s = 13     TeV collected by the ATLAS detector from 2015 to 2018 is used and corresponds to an integrated luminosity of 139     fb − 1 . The search targets the high Y -mass region, where the H and X have a significant Lorentz boost in the laboratory frame. A novel application of anomaly detection is used to define a general signal region, where events are selected solely because of their incompatibility with a learned background-only model. It is constructed using a jet-level tagger for signal-model-independent selection of the boosted X particle, representing the first application of fully unsupervised machine learning to an ATLAS analysis. Two additional signal regions are implemented to target a benchmark X decay into two quarks, covering topologies where the X is reconstructed as either a single large-radius jet or two small-radius jets. The analysis selects Higgs boson decays into b ¯ b , and a dedicated neural-network-based tagger provides sensitivity to the boosted heavy-flavor topology. No significant excess of data over the expected background is observed, and the results are presented as upper limits on the production cross section σ ( p p → Y → X H → q ¯ q b ¯ b ) for signals with m Y between 1.5 and 6 TeV and m X between 65 and 3000 GeV

    Measurement of substructure-dependent jet suppression in Pb+Pb collisions at 5.02 TeV with the ATLAS detector

    Get PDF
    The ATLAS detector at the Large Hadron Collider has been used to measure jet substructure modification and suppression in Pb+Pb collisions at a nucleon–nucleon center-of-mass energy √sNN = 5.02 TeV in comparison with proton–proton (pp) collisions at √s = 5.02 TeV. The Pb+Pb data, collected in 2018, have an integrated luminosity of 1.72 nb−1, while the ppdata, collected in 2017, have an integrated luminosity of 260 pb−1. Jets used in this analysis are clustered using the anti-kt algorithm with a radius parameter R = 0.4. The jet constituents, defined by both tracking and calorimeter information, are used to determine the angular scale rg of the first hard splitting inside the jet by reclustering them using the Cambridge–Aachen algorithm and employing the soft-drop grooming technique. The nuclear modification factor, RAA, used to characterize jet suppression in Pb+Pb collisions, is presented differentially in rg, jet transverse momentum, and in intervals of collision centrality. The RAA value is observed to depend significantly on jet rg. Jets produced with the largest measured rg are found to be twice as suppressed as those with the smallest rg in central Pb+Pb collisions. The RAA values do not exhibit a strong variation with jet pT in any of the rg intervals. The rg and pT dependence of jet RAA is qualitatively consistent with a picture of jet quenching arising from coherence and provides the most direct evidence in support of this approach
    corecore