282 research outputs found

    Fluctuating Dark Energy and the Luminosity Distance

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    The origin of dark energy driving the accelerated expansion of the universe is still mysterious. We explore the possibility that dark energy fluctuates, resulting in spatial correlations. Due to these fluctuations, the Hubble rate itself becomes a fluctuating quantity. We discuss the effect this has on measurements of type Ia supernovae, which are used to constrain the luminosity distance. We show that the luminosity distance is affected by spatial correlations in several ways. First, the luminosity distance becomes dressed by the fluctuations, thereby differing from standard Λ\LambdaCDM. Second, angular correlations become visible in the two-point correlation function of the luminosity distance. To investigate the latter we construct the angular power spectrum of luminosity distance fluctuations. We then perform a forecast for two supernova surveys, the ongoing Dark Energy Survey (DES) and the upcoming Legacy Survey of Space and Time (LSST), and compare this effect with relativistic lensing effects from perturbed Λ\LambdaCDM. We find that the signal can rise above the lensing effects and that LSST could test this effect for a large part of the parameter space. As an example, a specific realisation of such a scenario is that quantum fluctuations of some field in the early universe imprint spatial correlations with a predictable form in the dark energy density today. In this case, the Hubble rate fluctuates due to the intrinsic quantum nature of the dark energy density field. We study whether the signal of this specific model would be measurable, and conclude that testing this model with LSST would be challenging. However, taking into account a speed of sound cs<1c_s<1 of the dark energy fluid can make this model observable.Comment: 38 pages, 9 figure

    Prospects for detection and application of the alignment of galaxies with the large-scale velocity field

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    Studies of intrinsic alignment effects mostly focus on the correlations between the shapes of galaxies with each other or with the underlying density field of the large scale structure of the Universe. Lately, the correlation between the shapes of galaxies and the large-scale velocity field has been proposed as an additional probe of the large scale structure. We use a Fisher forecast to make a prediction for the detectability of this velocity-shape correlation with a combination of redshifts and shapes from the 4 MOST +LSST surveys, and radial velocity reconstruction from the Simons Observatory. The signal-to-noise ratio for the velocity-shape (dipole) correlation is 23, relative to 44 for the galaxy density-shape (monopole) correlation and for a maximum wave number of 0.2 Mpc-1 . Increasing the signal-to-noise ratio for higher values of the maximum wave numbers (respectively, 56 and 69, for a maximum wave number of 1 Mpc-1 ) indicate potential gains in the nonlinear regime. Encouraged by these predictions, we discuss two possible applications for the velocity-shape correlation. Measuring the velocity-shape correlation could improve the mitigation of selection effects induced by intrinsic alignments on galaxy clustering. We also find that velocity-shape measurements could potentially aid in determining the scale dependence of intrinsic alignments when multiple shape measurements of the same galaxies are provided

    Unveiling the nature of IGR J16283-4838

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    Context. One of the most striking discoveries of the INTEGRAL observatory is the existence of a previously unknown population of X-ray sources in the inner arms of the Galaxy. The investigations of the optical/NIR counterparts of some of them have provided evidence that they are highly absorbed high mass X-ray binaries hosting supergiants. Aims. We aim to identify the optical/NIR counterpart of one of the newly discovered INTEGRAL sources, IGR J16283-4838, and determine the nature of this system. Methods. We present optical and NIR observations of the field of IGR J16283-4838, and use the astrometry and photometry of the sources within it to identify its counterpart. We obtain its NIR spectrum, and its optical/NIR spectral energy distribution by means of broadband photometry. We search for the intrinsic polarization of its light, and its short and long-term photometric variability. Results. We demonstrate that this source is a highly absorbed HMXB located beyond the Galactic center, and that it may be surrounded by a variable circumstellar medium.Comment: 6 pages, 5 figures, accepted for publication in Astronomy & Astrophysic

    Eating and feeding disorders in pediatric age

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    Eating and feeding disorders are common in pediatric age and may be important to discover and recover the early symptoms in order to optimize the treatment and management

    Motor skills in children with primary headache: A pilot case-control study

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    Background: Headache is the most common painful manifestation in the developmental age, often accompanied by severe disability such as scholastic absenteeism, low quality of academic performance and compromised emotional functioning. The aim of the study is to evaluate praxic abilities in a population of children without aural migraine. Materials and methods: The test population consists of 10 subjects without migraine without aura (MwA), (8 Males) (mean age 8.40, SD ± 1.17) and 11 healthy children (7 Males) (mean age 8.27; SD ± 1.10; p = 0.800). All subjects underwent evaluation of motor coordination skills through the Battery for Children Movement Assessment (M-ABC). Results: The two groups (10 MwA vs 11 Controls) were similar for age (8.40 ± 1.17 vs 8.27 ± 1.10; p = 0.800), sex (p = 0.730), and BMI (p = 0.204). The migraine subjects show an average worse performance than the Movement ABC; specifically, migraineurs show significantly higher total score values (31.00 ± 23.65 vs 4.72 ± 2.61; p = 0.001), manual dexterity (12.10 ± 11.20 vs 2.04 ± 2.65; p = 0.009) and balance (14.85 ± 10.08 vs. 1.04 ± 1.05; p &lt;0.001). The mean percentile of migraine performance is significantly reduced compared to controls (9.00 ± 3.82 vs 51.00 ± 24.34, p &lt;0.001) (Table 1). Conclusion: Migraine can alter many cognitive and executive functions such as motor skills in developmental age

    Neuropsychomotricity in water: A new rehabilitative tool for neruodevelop-mental disorders

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    Neuropsychomotricity in water is a rehabilitative practice that avails itself just of the liquid element, as a mediator of relationships: in water yes they upset all dynamics, be they relational, of equilibrium, of movement and perception, due to the fact that proprioceptive sensations, created by bodily contact with water, they are different than those generated by contact with air

    Visuospatial skills in children affected by primary nocturnal enuresis: Rehabilitative proposals

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    The sphincterial control problems in childhood are very common, with relevant comorbidities (i.e.: difficulty in academic performance, sleep disturbances, minor neurological signs) involved in the complex process of maturation and learning, such as to cause a great deal of discomfort and related disorders in affected subjects. Enuresis is characterized by the involuntary urination in the absence of a physical disorder, socially unacceptable in places and at one stage of life where such control is acquired by the majority of subjects (about 5 years). The present study aims to evaluate the visuospatial skills in children affected by primary monosymptomatic nocturnal enuresis (PMNE). 31 PMNE children (16 males and 15 females) (mean age 10.87, SD ± 1.68) and 61 healthy children (32 males, 29 females) (mean age 11.03, SD ± 1.85, p = 0687) were evaluated for visuomotor skills with the Visual-Motor Integration Scale (VMI). PMNE subjects show a worse performance on average to VMI, especially in the total visual-motor integration test. This finding emphasizes the importance of a framework for global and more complex than is commonly implemented, across the border but framing the subject of enuretic symptoms in a more global perspective

    Psychopathological and psychodynamic hypotheses for pediatric stuttering

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    Stuttering is a common language alteration in pediatric age consisting in repetitions and blocks, which entail a break in the rhythm and melody of the speech. According to the WHO it is a disorder of the rhythm of the word, the subject knows precisely what he would like to say, but at the same time he is not able to say it. It is a great inconvenience for those affected, also because the slowing down of speaking is not about thought or cognitive skills

    A brief review about anxiety and aggressive behavior in pediatric age

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    Anxiety can be considered a normal experience of the human being and as such also of the child. It manifests itself in different ways according to the level of development: in the smaller the child, the more anxiety is expressed with manifestations that involve the whole organism, becoming evident either with motor excitement or with physical discomfort. As the psychic apparatus is structured, anxiety is experienced as an inner phenomenon and is experienced as an unpleasant state. Fortunately, we are all a bit anxious, even if there are some people who are more, others less
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