5,219 research outputs found
Editorial: Understanding developmental dyslexia: linking perceptual and cognitive deficits to reading processes
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
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
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
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
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
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
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 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 2.6 shift from 1 using the Planck public
likelihoods. We show that, owing to strong correlations with the reionization
optical depth and the primordial perturbation amplitude , a
tension on also appears between the results obtained with
the low () and high () multipoles
likelihoods. With Hillipop, another high- likelihood built from Planck
data, this difference is lowered to . In this case, the value
is still in disagreement with unity by , 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
measurements of the Atacama Cosmology Telescope (ACT) and South Pole
Telescope (SPT) experiments and obtain . The
Hillipop+ACT+SPT likelihood estimate of the optical depth is
which is now fully compatible with the low
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 CDM parameters with our combined
CMB data likelihood.Comment: accepted by A&
The unseen effect of pesticides: The impact on phytobiota structure and functions
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
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 < 0.0001) and left ventricular mass index (80.5 +/- 18.1 vs. 56.1 +/- 5.4 g/m(2); P < 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 < 0.0001) than controls. When patients and controls were grouped according to BMI [normal weight (BMI, >18 and <25 kg/m(2)), overweight (BMI, 25.1-30 kg/m(2)), and obese (BMI, >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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