Properties of finite Gaussians and the discrete-continuous transition

Weyl's formulation of quantum mechanics opened the possibility of studying the dynamics of quantum systems both in infinite-dimensional and finite-dimensional systems. Based on Weyl's approach, generalized by Schwinger, a self-consistent theoretical framework describing physical systems characterised by a finite-dimensional space of states has been created. The used mathematical formalism is further developed by adding finite-dimensional versions of some notions and results from the continuous case. Discrete versions of the continuous Gaussian functions have been defined by using the Jacobi theta functions. We continue the investigation of the properties of these finite Gaussians by following the analogy with the continuous case. We study the uncertainty relation of finite Gaussian states, the form of the associated Wigner quasi-distribution and the evolution under free-particle and quantum harmonic oscillator Hamiltonians. In all cases, a particular emphasis is put on the recovery of the known continuous-limit results when the dimension $d$ of the system increases.Comment: 21 pages, 4 figure

Talbot effect in cylindrical waveguides

We extend the theory of Talbot revivals for planar or rectangular geometry to the case of cylindrical waveguides. We derive a list of conditions that are necessary to obtain revivals in cylindrical waveguides. A phase space approach based on the Wigner and the Kirkwood-Rihaczek functions provides a pictorial representation of TM modes interference associated with the Talbot effect

Received Cradling Bias During the First Year of Life: A Retrospective Study on Children With Typical and Atypical Development

A population-level left cradling bias exists whereby 60–90% of mothers hold their infants on the left side. This left biased positioning appears to be mutually beneficial to both the mother and the baby's brain organization for processing of socio-emotional stimuli. Previous research connected cradling asymmetries and Autism Spectrum Disorders (ASD), entailing impairment in socio-communicative relationships and characterized by an early hypo-lateralization of brain functions. In this explorative study, we aimed to provide a contribution to the retrospective investigations by looking for early behavioral markers of neurodevelopmental disorders such as ASD. We hypothesized that an atypical trajectory in maternal cradling might be one of the possible signs of an interference in mother-infant socio-emotional communication, and thus of potential neurodevelopmental dysfunctions. To this aim, we examined photos depicting mother-child early cradling interactions by consulting family albums of 27 children later diagnosed with ASD and 63 typically developing children. As regards the first half of the first year of life, no differences were shown between maternal cradling-side preferences in typical and ASD groups, both exhibiting the left-cradling bias in the 0–3 months period, but not in the 3–6 months period. However, our results show dissimilar patterns of cradling preferences during the second half of the first year of life. In particular, the absence of left-cradling shown in typical mothers was not observed in ASD mothers, who exhibited a significant left-cradling bias in the 6–12 months age group. This difference might reflect the fact that mother-infant relationship involving children later diagnosed with ASD might remain “basic” because mothers experience a lack of social activity in such children. Alternatively, it may reflect the overstimulation in which mothers try to engage infants in response to their lack of responsiveness and social initiative. However, further investigations are needed both to distinguish between these two possibilities and to define the role of early typical and reversed cradling experiences on neurodevelopment

Describing astronomy identity of upper primary and middle school students through structural equation modeling

We describe how young students situate themselves with respect to astronomy through an identity framework that features four dimensions: interest, utility value, confidence, and conceptual knowledge. Overall, about 900 Italian students, from 5th to 9th grade (9-14 years old), were involved in the study. We tested our model using confirmatory factor analysis and structural equation modeling. Differences between girls and boys and across school levels were also investigated. Results show that interest has both a direct and an indirect effect on astronomy identity. The indirect effect of interest on identity is mediated by utility value. Moreover, confidence mediates the effect of interest on conceptual knowledge. Concerning differences between girls and boys, we found that the effect of interest on identity is greater for girls than for boys and that the utility value mediates the effect of interest on identity for boys but not for girls. Finally, our findings show also that the students' interest in astronomy and confidence in their performance decrease with age, with a potential negative impact on conceptual knowledge and future career choice in astronomy. The astronomy identity framework can be employed to examine the role of affective variables on performance and persistence in astronomy and to improve the design of teaching-learning activities that can potentially stimulate a lasting interest in astronomy

Received cradling bias during the first year of life: A retrospective study on children with typical and atypical development

A population-level left cradling bias exists whereby 60-90% of mothers hold their infants on the left side. This left biased positioning appears to be mutually beneficial to both the mother and the baby’s brain organization for processing of socio-emotional stimuli. Previous research connected cradling asymmetries and Autism Spectrum Disorders (ASD), entailing impairment in socio- communicative relationships and characterized by an early hypo-lateralization of brain functions. In this explorative study, we aimed to provide a contribution to the retrospective investigations by looking for early behavioral markers of neurodevelopmental disorders such as ASD. We hypothesized that an atypical trajectory in maternal cradling might be one of the possible signs of an interference in mother-infant socio-emotional communication, and thus of potential neurodevelopmental dysfunctions. To this aim, we examined photos depicting mother-child early cradling interactions by consulting family albums of 27 children later diagnosed with autism and 63 typically developing children. As regards the first half of the first year of life, no differences were shown between maternal cradling-side preferences in typical and ASD groups, both exhibiting the left-cradling bias in the 0-3 months period, but not in the 3-6 months period. However, our results show dissimilar patterns of cradling preferences during the second half of the first year of life. In particular, the absence of left-cradling shown in typical mothers was not observed in ASD mothers, who exhibited a significant left-cradling bias in the 6-12 months age group. This difference might reflect the fact that mother-infant relationship involving children later diagnosed with ASD might remain “basic” because mothers experience a lack of social activity in such children. Alternatively, it may reflect the overstimulation in which mothers try to engage infants in response to their lack of responsiveness and social initiative. However, further investigations are needed both to distinguish between these two possibilities and to define the role of early typical and reversed cradling experiences on neurodevelopment

Latest Triassic onset of the Central Atlantic Magmatic Province (CAMP) volcanism in the Fundy Basin (Nova Scotia): New stratigraphic constraints

In this paper we investigate the stratigraphic relationship between the emplacement of the CAMP basalts and the Triassic–Jurassic (Tr–J) boundary in the Fundy Basin (Nova Scotia, Canada). This is one of the best exposed of the synrift basins of eastern North America (ENA) formed as a consequence of the rifting that led to the formation of the Atlantic Ocean. The Triassic palynological assemblages found in the sedimentary rocks below (uppermost Blomidon Formation) and just above the North Mountain Basalt (Scots Bay Member of the McCoy Brook Formation) indicate that CAMP volcanism, at least in Nova Scotia, is entirely of Triassic age, occurred in a very short time span, and may have triggered the T–J boundary biotic and environmental crisis. The palynological assemblage from the Blomidon Formation is characterised by the dominance of the Circumpolles group (e.g. Gliscopollis meyeriana, Corollina murphyae, Classopollis torosus) which crosses the previously established Tr–J boundary.The Triassic species Patinasporites densus disappears several centimetres below the base of the North Mountain basalt, near the previously interpreted Tr–J boundary. The lower strata of the Scots Bay Member yielded a palynological assemblage dominated by Triassic bisaccate pollens (e.g Lunatisporites acutus, L. rhaeticus Lueckisporites sp., Alisporites parvus) with minor specimens of the Circumpolles group. Examination of the state of preservation and thermal alteration of organic matter associated with the microfloral assemblages precludes the possibility of recycling of the Triassic sporomorphs from the older strata. Our data argue against the previous definition of the Tr–J boundary in the ENA basins, which was based mainly on the last occurrence of P. densus. Consequently, it follows that the late Triassic magnetostratigraphic correlations should be revised considering that chron E23r, which is correlated with the last occurrence of P. densus in the Newark basin, does not occur at the Tr–J boundary but marks rather a late Triassic (probably Rhaetian) reversal

40Ar/39Ar ages of CAMP in North America: implications for the Triassic-Jurassic boundary and the 40K decay constant bias

The Central Atlantic magmatic province (CAMP) is one of the largest igneous provinces on Earth (>107 km²) and spanning four continents. Recent high-precision 40Ar/39Ar dating of mineral separates has provided important constraints on the age, duration, and geodynamic history of CAMP. Yet, the North American CAMP is strikingly under-represented in this dating effort. Here we present 13 new statistically robust plateau, mini-plateau and isochron ages obtained on plagioclase and sericite separates from lava flows from the Fundy (n = 10; Nova Scotia, Canada) and Hartford and Deerfield (n = 3; U.S.A.) basins. Ages mostly range from 198.6 ± 1.1 to 200.1 ± 1.4 Ma (2σ), with 1 date substantially younger at 190.6 ± 1.0 Ma. Careful statistical regression shows that ages from the upper (199.7.0 ± 1.5 Ma) and bottom (200.1 ± 0.9 Ma) units of the lava pile in the Fundy basin are statistically indistinguishable, confirming a short duration emplacement (<< 1.8 Ma; ≤1 Ma). Three ages obtained on the Hartford (198.6 ± 2.0 Ma and 199.8 ± 1.1 Ma) and Deerfield (199.3 ± 1.2 Ma) basins were measured on sericite from the upper lava flow units. We interpret these dates as reflecting synemplacement hydrothermal activity within these units. Collectively, CAMP ages gathered so far suggest a short duration of the main magmatic activity (2-3 Ma), but also suggest the possibility of a temporal migration of the active magmatic centers from north to south. Such a migration challenges a plume model that would postulate a radial outward migration of the magmatism and is more compatible with other models such as the supercontinent global warming hypothesis. When compared to the age of the Triassic-Jurassic boundary, the filtered CAMP age database suggests that the onset of the magmatic activity precedes the limit by at least few hundred thousand years, therefore suggesting a causal relationship between CAMP and the end of Triassic mass extinction. An age at 191 Ma possibly suggests a minor CAMP late tailing activity (190-194 Ma) which has already observed for dykes and sills in Africa and Brazil. We speculate that, if real, this late activity can be due to a major extensional event, possibly heralding the oceanisation process at ~190 Ma. Comparison between high quality U/Pb and 40Ar/39Ar ages of pegmatite lenses from the North Mountain basalts confirms a ~1% bias between the two chronometers. This discrepancy is likely attributed to the miscalibration of the 40K decay constants, in particular the electron capture branch

Optical Galton board

Quantum Matter and Optic

Pixel segmented ionization chamber for therapeutical beams of photons and hadrons

Abstract A fast and precise detector to monitor on-line the dose delivered by an active scanning therapeutical beam has been built and tested

Electron-radiation interaction in a Penning trap: beyond the dipole approximation

We investigate the physics of a single trapped electron interacting with a radiation field without the dipole approximation. This gives new physical insights in the so-called geonium theory.Comment: 12 pages, RevTeX, 6 figures, Approved for publication in Phys. Rev.