5,219 research outputs found

    Editorial: Understanding developmental dyslexia: linking perceptual and cognitive deficits to reading processes

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    The problem of causation has proven particularly elusive in the case of developmental dyslexia (DD). The field has been dominated by very general hypotheses, such as the idea that DD is caused by a phonological deficit and/or an impairment of the magnocellular pathway. Results are contrasting and causal unidirectional links have not been persuasively demonstrated. Some studies in the Research Topic (RT) re-examine these general hypotheses from the critical perspective of more selective predictions. Others focus on less general deficit hypotheses and stay closer to reading by investigating specific aspects of the reading process such as orthographic learning ability or the ability to deal with multiple-stimulus displays. Studies benefit from new research paradigms as well as new information from research areas such as neuroimaging or genetics. Below, we sketch the general questions tackled by these studies

    Measurement of the ratio h/e with a photomultiplier tube and a set of LEDs

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    We propose a laboratory experience aimed at undergraduate physics students to understand the main features of the photoelectric effect and to perform a measurement of the ratio h/e, where h is the Planck's constant and e is the electron charge. The experience is based on the method developed by Millikan for his measurements on the photoelectric effect in the years from 1912 to 1915. The experimental setup consists of a photomultiplier tube (PMT) equipped with a voltage divider properly modified to set variable retarding potentials between the photocathode and the first dynode, and a set of LEDs emitting at different wavelengths. The photocathode is illuminated with the various LEDs and, for each wavelength of the incident light, the output anode current is measured as a function of the retarding potential applied between the cathode and the first dynode. From each measurement, a value of the stopping potential for the anode current is derived. Finally, the stopping potentials are plotted as a function of the frequency of the incident light, and a linear fit is performed. The slope and the intercept of the line allow respectively to evaluate the ratio h/e and the ratio W/e, where W is the work function of the photocathode.Comment: 14 pages, 4 figure

    The Lira’s purchasing power from Italy’s unification to the single European Currency

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    This article analyses the behaviour of several price indexes over the whole life of the Italian lira (1861-1998), and for various sub-periods defined by the exchange-rate regimes of the Italian monetary history. We focus on the persistence and stationarity properties of the inflation process and their dependence on the real cycle. An international comparison with the United States and the United Kingdom further supports the conclusion that Italian inflation was abnormal as far as its mean value, degree of persistence and relationship to the real cycle are concerned. In particular, we find that the output-inflation relationship had a textbook-like, positive slope only during periods of low inflation and low production volatility

    Exploring the phase diagram of the two-impurity Kondo problem

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    A system of two exchange-coupled Kondo impurities in a magnetic field gives rise to a rich phase space hosting a multitude of correlated phenomena. Magnetic atoms on surfaces probed through scanning tunnelling microscopy provide an excellent platform to investigate coupled impurities, but typical high Kondo temperatures prevent field-dependent studies from being performed, rendering large parts of the phase space inaccessible. We present an integral study of pairs of Co atoms on insulating Cu2N/Cu(100), which each have a Kondo temperature of only 2.6 K. In order to cover the different regions of the phase space, the pairs are designed to have interaction strengths similar to the Kondo temperature. By applying a sufficiently strong magnetic field, we are able to access a new phase in which the two coupled impurities are simultaneously screened. Comparison of differential conductance spectra taken on the atoms to simulated curves, calculated using a third order transport model, allows us to independently determine the degree of Kondo screening in each phase.Comment: paper: 14 pages, 4 figures; supplementary: 3 pages, 1 figure, 1 tabl

    Testicular endocrine activity is upregulated by D-Aspartic acid in the green frog Rana esculenta

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    This study investigated the involvement of D-aspartic acid (D-Asp) in testicular steroidogenesis of the green frog Rana esculenta and its effect on stimulation of thumb pad morphology and glandular activity, a typical testosterone-dependent secondary sexual characteristic in this amphibian species. In the testis, D-Asp concentrations vary significantly during the reproductive cycle: they are low in pre- and post-reproductive periods, but reach peak levels in the reproductive period (140-236 nmol/g wet tissue). Moreover, the concentrations of D-Asp in the testis through the sexual cycle positively match the testosterone levels in the gonad and the plasma. The racemase activity evaluated during the cycle expresses its peak when D-Asp and testosterone levels are highest, that is, during the reproductive period, confirming the synthesis of D-Asp from L-Asp by an aspartate racemase. Short-term in vivo experiments consisting of a single injection of D-Asp (2.0 micro mol/g body weight) demonstrated that this amino acid accumulates significantly in the testis, and after 3 h its uptake is coupled with a testosterone increase in both testis and plasma. Moreover, within 18 h of amino acid administration, the D-Asp concentration in the testis decreased along with the testosterone titer to prestimulation levels. Other amino acids (L-Asp, D-Glu and L-Glu) used instead of D-Asp were ineffective, confirming that the significant increase in testicular testosterone was a specific feature of this amino acid. In long-term experiments, D-Asp had been administered chronically to frogs caught during the three phases of the reproductive cycle, inducing testosterone increase and 17beta-estradiol decrease in the gonad during the pre- and post-reproductive period, and vice versa during the reproductive period

    Diversification of spatiotemporal expression and copy number variation of the echinoid hbox12/pmar1/micro1 multigene family

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    Changes occurring during evolution in the cis-regulatory landscapes of individual members of multigene families might impart diversification in their spatiotemporal expression and function. The archetypal member of the echinoid hbox12/pmar1/micro1 family is hbox12-a, a homeobox-containing gene expressed exclusively by dorsal blastomeres, where it governs the dorsal/ventral gene regulatory network during embryogenesis of the sea urchin Paracentrotus lividus. Here we describe the inventory of the hbox12/pmar1/micro1 genes in P. lividus, highlighting that gene copy number variation occurs across individual sea urchins of the same species. We show that the various hbox12/pmar1/micro1 genes group into three subfamilies according to their spatiotemporal expression, which ranges from broad transcription throughout development to transient expression in either the animal hemisphere or micromeres of the early embryo. Interestingly, the promoter regions of those genes showing comparable expression patterns are highly similar, while differing from those of the other subfamilies. Strikingly, phylogenetic analysis suggests that the hbox12/pmar1/micro1 genes are species-specific, exhibiting extensive divergence in their noncoding, but not in their coding, sequences across three distinct sea urchin species. In spite of this, two micromere-specific genes of P. lividus possess a TCF/LEF-binding motif in a similar position, and their transcription relies on Wnt/ f-catenin signaling, similar to the pmar1 and micro1 genes, which in other sea urchin species are involved in micromere specification. Altogether, our findings suggest that the hbox12/pmar1/micro1 gene family evolved rather rapidly, generating paralogs whose cis-regulatory sequences diverged following multiple rounds of duplication from a common ancestor

    Relieving tensions related to the lensing of CMB temperature power spectra

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    The angular power spectra of the cosmic microwave background (CMB) temperature anisotropies reconstructed from Planck data seem to present too much gravitational lensing distortion. This is quantified by the control parameter ALA_L that should be compatible with unity for a standard cosmology. With the Class Boltzmann solver and the profile-likelihood method, for this parameter we measure a 2.6σ\sigma shift from 1 using the Planck public likelihoods. We show that, owing to strong correlations with the reionization optical depth τ\tau and the primordial perturbation amplitude AsA_s, a 2σ\sim2\sigma tension on τ\tau also appears between the results obtained with the low (30\ell\leq 30) and high (30<250030<\ell\lesssim 2500) multipoles likelihoods. With Hillipop, another high-\ell likelihood built from Planck data, this difference is lowered to 1.3σ1.3\sigma. In this case, the ALA_L value is still in disagreement with unity by 2.2σ2.2\sigma, suggesting a non-trivial effect of the correlations between cosmological and nuisance parameters. To better constrain the nuisance foregrounds parameters, we include the very high \ell measurements of the Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT) experiments and obtain AL=1.03±0.08A_L = 1.03 \pm 0.08. The Hillipop+ACT+SPT likelihood estimate of the optical depth is τ=0.052±0.035,\tau=0.052\pm{0.035,} which is now fully compatible with the low \ell likelihood determination. After showing the robustness of our results with various combinations, we investigate the reasons for this improvement that results from a better determination of the whole set of foregrounds parameters. We finally provide estimates of the Λ\LambdaCDM parameters with our combined CMB data likelihood.Comment: accepted by A&

    The unseen effect of pesticides: The impact on phytobiota structure and functions

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    In the last years, the diffusion and implementation of next-generation sequencing and the reduction of costs raised the interest in phytyobiome studies allowing to dissect the ecological interactions regulating the holobiont. Indeed, crop plants are associated with a wide diversity of microorganisms in all their parts. Crop microbiota influences plant phenotype, growth, yield and quality by contributing to plant resistance toward diseases, plant adaptation to abiotic stresses, and plant nutrition. The association between terrestrial plants and microbes developed at least 460 million years ago, as suggested by the fossil evidence of the earliest land plants, indicating the essential role of microbes for plants. Recent studies indicate that plants actively recruit beneficial microorganisms to facilitate their adaptation to environmental conditions. Cultivation methods and disease control measures can influence plant microbiome structure and functions. Both pesticide and biological control agent applications may alter the biodiversity inside the phytobiota and suppress beneficial functions. Nonetheless, to date, the effects of disease control measures on phytobiota and their possible side consequences on plant growth, crop productivity and quality remain a neglected field of study. The present work summarizes the known effects on phytobiota providing evidence about the role of plant microbial community in determining the overall efficacy of the applied control measure and suggests that future studies on plant disease control consider also the microbe-mediated effects on plant fitness

    The cardiovascular risk of young women with polycystic ovary syndrome: an observational, analytical, prospective case-control study

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    To evaluate the cardiovascular risk of polycystic ovary syndrome (PCOS), we investigated lipid profile, metabolic pattern, and echocardiography in 30 young women with PCOS and 30 healthy age- and body mass index (BMI)-matched women. PCOS women had higher fasting glucose and insulin levels, homeostasis model assessment score of insulin sensitivity, total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels, and TC/high density lipoprotein cholesterol (HDL-C) ratio and lower HDL-C levels than controls. Additionally, PCOS women had higher left atrium size (32.0 +/- 4.9 vs. 27.4 +/- 2.1 mm; P &lt; 0.0001) and left ventricular mass index (80.5 +/- 18.1 vs. 56.1 +/- 5.4 g/m(2); P &lt; 0.0001) and lower left ventricular ejection fraction (64.4 +/- 4.1 vs. 67.1 +/- 2.6%; P = 0.003) and early to late mitral flow velocity ratio (1.6 +/- 0.4 vs. 2.1 +/- 0.2; P &lt; 0.0001) than controls. When patients and controls were grouped according to BMI [normal weight (BMI, &gt;18 and &lt;25 kg/m(2)), overweight (BMI, 25.1-30 kg/m(2)), and obese (BMI, &gt;30 kg/m(2))], the differences between PCOS women and controls were maintained in overweight and obese women. In normal weight PCOS women, a significant increase in left ventricular mass index and a decrease in diastolic filling were observed, notwithstanding no change in TC, LDL-C, HDL-C, TC/HDL-C ratio, and TG compared with controls. In conclusion, our data show the detrimental effect of PCOS on the cardiovascular system even in young women asymptomatic for cardiac disease
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