2,544 research outputs found

    IBIS (Interferometric BIdimensional spectrometer)

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    IBIS is a new instrument for solar bidimensional spectroscopy, now under construction at the Arcetri Astrophysical Observatory. It essentially consists of two Fabry-Perot interferometers, piezo-scanned and capacity servo-controlled, which are used in classic mount and in axial-mode, in series with a narrow-band interference filter. This instrument will operate on a large field of view (80����) and on a large wavelength range (5800–8600 ˚A), with high spectral (λ/Δλ � 250000), spatial (�0.2) and temporal (� 5 frames s−1) resolution. When completed in 2002, it will be one of the leading instruments for solar research, well suited for a new generation telescopes such as THEMIS

    Enumerating 3-generated axial algebras of Monster type

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    An axial algebra is a commutative non-associative algebra generated by axes, that is, primitive, semisimple idempotents whose eigenvectors multiply according to a certain fusion law. The Griess algebra, whose automorphism group is the Monster, is an example of an axial algebra. We say an axial algebra is of Monster type if it has the same fusion law as the Griess algebra. The 22-generated axial algebras of Monster type, called Norton-Sakuma algebras, have been fully classified and are one of nine isomorphism types. In this paper, we enumerate and construct the 33-generated axial algebras of Monster type which do not contain a 5A5\textrm{A}, or 6A6\textrm{A} subalgebra.Comment: 27 pages. arXiv admin note: text overlap with arXiv:1804.0058

    3D photospheric velocity field of a Supergranular cell

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    We investigate the plasma flow properties inside a Supergranular (SG) cell, in particular its interaction with small scale magnetic field structures. The SG cell has been identified using the magnetic network (CaII wing brightness) as proxy, applying the Two-Level Structure Tracking (TST) to high spatial, spectral and temporal resolution observations obtained by IBIS. The full 3D velocity vector field for the SG has been reconstructed at two different photospheric heights. In order to strengthen our findings, we also computed the mean radial flow of the SG by means of cork tracing. We also studied the behaviour of the horizontal and Line of Sight plasma flow cospatial with cluster of bright CaII structures of magnetic origin to better understand the interaction between photospheric convection and small scale magnetic features. The SG cell we investigated seems to be organized with an almost radial flow from its centre to the border. The large scale divergence structure is probably created by a compact region of constant up-flow close to the cell centre. On the edge of the SG, isolated regions of strong convergent flow are nearby or cospatial with extended clusters of bright CaII wing features forming the knots of the magnetic network.Comment: 7 pages, submitted to A&A, referee's comments include

    Radiative transfer effects on Doppler measurements as sources of surface effects in sunspot seismology

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    We show that the use of Doppler shifts of Zeeman sensitive spectral lines to observe wavesn in sunspots is subject to measurement specific phase shifts arising from, (i) altered height range of spectral line formation and the propagating character of p mode waves in penumbrae, and (ii) Zeeman broadening and splitting. We also show that these phase shifts depend on wave frequencies, strengths and line of sight inclination of magnetic field, and the polarization state used for Doppler measurements. We discuss how these phase shifts could contribute to local helioseismic measurements of 'surface effects' in sunspot seismology.Comment: 12 pages, 4 figures, Accepted for publication in the Astrophysical Journal Letter

    A knowledge-intensive approach to process similarity calculation

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    Process model comparison and similar processes retrieval are key issues to be addressed in many real world situations, and particularly relevant ones in some applications (e.g., in medicine), where similarity quantification can be exploited in a quality assessment perspective. Most of the process comparison techniques described in the literature suffer from two main limitations: (1) they adopt a purely syntactic (vs. semantic) approach in process activity comparison, and/or (2) they ignore complex control flow information (i.e., other than sequence). These limitations oversimplify the problem, and make the results of similarity-based process retrieval less reliable, especially when domain knowledge is available, and can be adopted to quantify activity or control flow construct differences. In this paper, we aim at overcoming both limitations, by introducing a framework which allows to extract the actual process model from the available process execution traces, through process mining techniques, and then to compare (mined) process models, by relying on a novel distance measure. The novel distance measure, which represents the main contribution of this paper, is able to address issues (1) and (2) above, since: (1) it provides a semantic, knowledge-intensive approach to process activity comparison, by making use of domain knowledge; (2) it explicitly takes into account complex control flow constructs (such as AND and XOR splits/joins), thus fully considering the different semantic meaning of control flow connections in a reliable way. The positive impact of the framework in practice has been tested in stroke management, where our approach has outperformed a state-of-the art literature metric on a real world event log, providing results that were closer to those of a human expert. Experiments in other domains are foreseen in the future

    Small-scale swirl events in the quiet Sun chromosphere

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    Recent progress in instrumentation enables solar observations with high resolution simultaneously in the spatial, temporal, and spectral domains. We use such high-resolution observations to study small-scale structures and dynamics in the chromosphere of the quiet Sun. We analyze time series of spectral scans through the Ca II 854.2nm spectral line obtained with the CRISP instrument at the Swedish 1-m Solar Telescope. The targets are quiet Sun regions inside coronal holes close to disc-centre. The line core maps exhibit relatively few fibrils compared to what is normally observed in quiet Sun regions outside coronal holes. The time series show a chaotic and dynamic scene that includes spatially confined "swirl" events. These events feature dark and bright rotating patches, which can consist of arcs, spiral arms, rings or ring fragments. The width of the fragments typically appears to be on the order of only 0.2", which is close to the effective spatial resolution. They exhibit Doppler shifts of -2 to -4 km/s but sometimes up to -7 km/s, indicating fast upflows. The diameter of a swirl is usually of the order of 2". At the location of these swirls, the line wing and wide-band maps show close groups of photospheric bright points that move with respect to each other. A likely explanation is that the relative motion of the bright points twists the associated magnetic field in the chromosphere above. Plasma or propagating waves may then spiral upwards guided by the magnetic flux structure, thereby producing the observed intensity signature of Doppler-shifted ring fragments.Comment: 4 pages, 3 figures, A&A Letter, accepted (final version

    Eating Disorders

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    Anorexia and bulimia are diseases known since ancient times, but in recent years their frequency has been continuously increasing in most industrialized countries. The etiology of these disorders can be traced back to the interaction between genetic predisposition, childhood experiences, and cultural pressures. As regards the course, a certain tendency to chronicity can be observed, and in extreme cases, they can cause death. According to the diagnostic classification of the DSM-5, eating disorders include anorexia nervosa, bulimia nervosa, binge eating disorder (which, compared to DSM-IV, becomes a diagnostic category in its own right), and other specified feeding and eating disorders (OSFED). Both anorexia and bulimia cause potentially serious medical complications. To maximize the chances of good outcomes a multidisciplinary intervention is necessary with staff including professionally heterogeneous figures: a psychiatrist, a psychologist, and a nutritionist. Therapeutic success for these patients is limited. Eating disorders require, among psychiatric disorders, the greatest possible collaboration between different professional figures with different specializations

    The Stability of TSH, and Thyroid Hormones, in Patients Treated With Tablet, or Liquid Levo-Thyroxine

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    Approximately, 5% of the population is affected by hypothyroidism, mainly women and persons aged more than 60 years. After the diagnosis of hypothyroidism the usual therapy is tablet levothyroxine (L-T4), with a monitoring of the thyroid-stimulating hormone (TSH) level in primary hypothyroidism every 6-8 weeks and L-T4 is adjusted as necessary to reach an euthyroid state. Once TSH is stabilized in the normal range, it is recommended to conduct annual testing in the treated subjects to warrant suitable replacement. More recently advances regarding L-T4 treatment are the introduction of new oral formulations: the liquid solution, and soft gel capsule. The soft gel capsule permits a quick dissolution in the acid gastric pH. The liquid preparation does not require an acid gastric environment. Many pharmacokinetic studies demonstrated a more rapid absorption for the liquid L-T4, or capsule, than with tablet. Many studies have shown that the liquid, or capsule, formulations can overcome the interaction with foods, drugs or malabsorptive conditions, that are able to impair the tablet L-T4 absorption. Lately studies have suggested that liquid L-T4 can permit to maintain more efficiently normal TSH levels in hypothyroid patients in the long-term follow-up, than tablet L-T4, both in patients with malabsorptive states, and in those without malabsorption. Further large, prospective, longitudinal studies are needed to evaluate the stability of TSH, in hypothyroid patients treated with different L-T4 formulations

    Breakdown at Medium Frequencies of Thermally-Aged Polyester Films

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    This article investigates the evolution of electrical properties of polyethylene terephthalate (PET) with thermal aging. Electrical tests are performed within a wide range of frequencies in order to simulate the application conditions of insulating materials in inverter-fed machines. In particular, for the aging conditions considered, the real part of permittivity showed to be correlated with the concentration of the degradation species, investigated through FTIR. On the contrary, the dielectric breakdown at high frequencies showed to be independent from the corresponding values of the dissipation factor (tanδ). This behavior would imply that thermal runaway is not the principal phenomenon leading to the dielectric failure

    Decoding the Genomic Landscape of Pomegranate: A Genome-Wide Analysis of Transposable Elements and Their Structural Proximity to Functional Genes

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    Transposable elements (TEs) significantly drive dynamic changes that characterize genome evolution. However, understanding the variability associated with TE insertions among different cultivars remains challenging. The pomegranate (Punica granatum L.) has yet to be extensively studied regarding the roles of TEs in the diversification of cultivars. Herein, we explored the genome distribution of TEs and its potential functional implications among four pomegranate cultivars, ‘Bhagwa’, ‘Dabenzi’, ‘Taishanhong’ and ‘Tunisia’, whose genome sequences are available. A total of 8404 full-length TEs were isolated. The content of TEs varied among the cultivars, ranging from 41.67% of ‘Taishanhong’ to 52.45% of ‘Bhagwa’. In all cultivars, the Gypsy superfamily of retrotransposons accounted for a larger genome proportion than the Copia superfamily. Seventy-three full-length TEs were found at the same genomic loci in all four cultivars. By contrast, 947, 297, 311, and 874 TEs were found exclusively in ‘Bhagwa’, ‘Dabenzi’, ‘Taishanhong’, and ‘Tunisia’ cultivars, respectively. Phylogenetic clustering based on the presence of TE insertions in specific loci reflected the geographic origins of the cultivars. The insertion time profiles of LTR-REs were studied in the four cultivars. Shared elements across the four cultivars exhibited, on average, a more ancient insertion date than those exclusive to three, two, or one cultivars. The majority of TEs were located within 1000 bp from the nearest gene. This localization was observed for 57% of DNA TEs and 55% of long-terminal repeat retrotransposons (LTR-RE). More than 10% of TEs resulted inserted within genes. Concerning DNA TEs, 3.91% of insertions occurred in introns, while 2.42% occurred in exons. As to LTR-REs, 4% of insertions occurred in exons and 1.98% in introns. Functional analysis of the genes lying close to TEs was performed to infer if differences in TE insertion can affect the fruit quality. Two TE insertions were found close to two genes encoding 4-coumarate--CoA ligase, an enzyme involved in the phenylpropanoid pathway. Moreover, a TIR/Mariner element was found within the exon of a gene encoding anthocyanidin reductase in the ‘Tunisia’ genotype, crucial in the biosynthesis of flavan-3-ols and proanthocyanidins, strictly correlated with the nutraceutical properties of pomegranate. Although functional and metabolomic studies are essential to elucidate the consequences of TE insertions, these results contribute to advancing our comprehension of the role of TEs in pomegranate genomics, providing insights for crop breeding
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