187^{187}Re(\gamm,n) cross section close to and above the neutron threshold

The neutron capture cross section of the unstable nucleus $^{186}$Re is studied by investigating the inverse photodisintegration reaction $^{187}$Re($\gamma$,n). The special interest of the {\it s}-process branching point $^{186}$Re is related to the question of possible {\it s}-process contributions to the abundance of the {\it r}-process chronometer nucleus ^{187}$Re. We use the photoactivation technique to measure photodisintegration rates. Our experimental results are in good agreement with two different statistical model calculations. Although the cross sections predicted by both models for the inverse reaction$^{186}$Re(n,$\gamma$) is too low to remove the overproduction of$^{186}$Os; the two predicted neutron-capture cross sections differ by a factor of 2.4; this calls for future theoretical study.Comment: Phys. Rev. C, in pres

Tuning the Re/Os Clock: Stellar-Neutron Cross Sections

The neutron-capture cross sections of 186,187Os have been recently measured at the CERN neutron time-of-flight facility n_TOF for an improved evaluation of the Re/Os cosmo-chronometer. This experimental information was complemented by nuclear model calculations for obtaining the proper astrophysical reaction rates at s-process temperatures. The calculated results and their implications for the determination of the time-duration of nucleosynthesis during galactic chemical evolution is discusse

The role of cerebellar circuitry alterations in the pathophysiology of autism spectrum disorders

The cerebellum has been repeatedly implicated in gene expression, rodent model and post-mortem studies of autism spectrum disorder (ASD). How cellular and molecular anomalies of the cerebellum relate to clinical manifestations of ASD remains unclear. Separate circuits of the cerebellum control different sensorimotor behaviors, such as maintaining balance, walking, making eye movements, reaching, and grasping. Each of these behaviors has been found to be impaired in ASD, suggesting that multiple distinct circuits of the cerebellum may be involved in the pathogenesis of patients' sensorimotor impairments. We will review evidence that the development of these circuits is disrupted in individuals with ASD and that their study may help elucidate the pathophysiology of sensorimotor deficits and core symptoms of the disorder. Preclinical studies of monogenetic conditions associated with ASD also have identified selective defects of the cerebellum and documented behavioral rescues when the cerebellum is targeted. Based on these findings, we propose that cerebellar circuits may prove to be promising targets for therapeutic development aimed at rescuing sensorimotor and other clinical symptoms of different forms of ASD

Correlation functions of disorder operators in massive ghost theories

The two-dimensional ghost systems with negative integral central charge received much attention in the last years for their role in a number of applications and in connection with logarithmic conformal field theory. We consider the free massive bosonic and fermionic ghost systems and concentrate on the non-trivial sectors containing the disorder operators. A unified analysis of the correlation functions of such operators can be performed for ghosts and ordinary complex bosons and fermions. It turns out that these correlators depend only on the statistics although the scaling dimensions of the disorder operators change when going from the ordinary to the ghost case. As known from the study of the ordinary case, the bosonic and fermionic correlation functions are the inverse of each other and are exactly expressible through the solution of a non-linear differential equation.Comment: 8 pages, late

Clustering or scattering? The spatial distribution of cropland in a metropolitan region, 1960-2010

This article presents empirical results of a multivariate analysis run with the aim to identify (apparent and latent) socioeconomic transformations that shape the distribution pattern of cropland in a metropolitan region of southern Europe (Athens, Greece) over a sufficiently long time interval spanning from 1960 to 2010. The study area is representative of monocentric cities expanding in an unregulated fashion and experiencing sequential cycles of economic growth and recession. Percent share of cropland in total municipal area increased moderately over time. A non-linear relationship with the distance from downtown Athens was also observed, indicating that the highest rates of cropland were observed at a distance ranging between 20 and 30 km from the inner city. A multivariate regression was run by decade at each municipality of the study area using 11 predictors with the aim to identify the factors most associated with cropland decline along urban fringes. Distance from downtown Athens, soil and climate quality, population growth rate, and competing land use were the most relevant factors correlated with cropland expansion (or decline) in the study area. Competing land use was particularly important for cropland decline in a first urbanization phase (1960-1980), while population growth rate-and hence an increased human pressure-was positively associated with agricultural areas in a subsequent phase (1990-2010). In these regards, per capita urban land had a non-linear spatial behavior, being correlated negatively with cropland in 1960 and 1970 and positively in 2010, possibly indicating a moderate change from a monocentric model towards a more dispersed metropolitan configuration impacting distribution of agricultural areas. Empirical findings of this study suggest that effective strategies supporting peri-urban agriculture require a comprehensive knowledge of the local socioeconomic context and relevant biophysical conditions-specifically focusing on the dominant soil and climate attributes

A first assessment of genetic variability in the longhorn beetle Rosalia alpina (Coleoptera: Cerambycidae) from the Italian Apennines

The Rosalia longicorn (Rosalia alpina) is a strictly protected saproxylic beetle, widely distributed in Central and Southern Europe and mainly associated with ancient beech forests. To improve knowledge about the conservation status of R. alpina in Italy, available molecular markers (microsatellites and mitochondrial cytochrome c oxidase I(COI)) were tested for the first time on Italian populations. The study was performed in four sampling sites distributed in two areas placed in Northern (“Foreste Casentinesi” National Park) and Central Apennines (“Abruzzo, Lazio and Molise” National Park) where populational data about Rosalia longicorn were collected in the framework of the European LIFE MIPP Project. The genetic relationship among Apennine and Central/South-eastern European populations was explored by a comparison with mitochondrial DNA (mtDNA) data from literature. Microsatellite markers were only partially informative when applied to R. alpina Italian individuals, although providing some preliminary indication on an extensive gene flow among populations from the Apennines and local ongoing processes of genetic erosion. Genetic data are consistent with previous ecological data suggesting that the maintenance of variability in this species could be related to both habitat continuity and preservation of large senescent or standing dead trees in forests. Finally, a peculiar origin of the Apennine populations of R. alpina from a putative “Glacial Refugium” in Italy was inferred through COI data. The high genetic distance scored among the analysed populations and those from Central and South-eastern Europe indicates that the R. alpina deme from Apennine Mountains might represent a relevant conservation unit in Europe. Further genetic analyses will allow assessing other possible conservation units of R. alpina and, thus, defining large-scale conservation strategies to protect this endangered longhorn beetle in Europe

Saccadic eye movement abnormalities in autism spectrum disorder indicate dysfunctions in cerebellum and brainstem

BACKGROUND: Individuals with autism spectrum disorder (ASD) show atypical scan paths during social interaction and when viewing faces, and recent evidence suggests that they also show abnormal saccadic eye movement dynamics and accuracy when viewing less complex and non-social stimuli. Eye movements are a uniquely promising target for studies of ASD as their spatial and temporal characteristics can be measured precisely and the brain circuits supporting them are well-defined. Control of saccade metrics is supported by discrete circuits within the cerebellum and brainstem - two brain regions implicated in magnetic resonance (MR) morphometry and histopathological studies of ASD. The functional integrity of these distinct brain systems can be examined by evaluating different parameters of visually-guided saccades. METHODS: A total of 65 participants with ASD and 43 healthy controls, matched on age (between 6 and 44-years-old), gender and nonverbal IQ made saccades to peripheral targets. To examine the influence of attentional processes, blocked gap and overlap trials were presented. We examined saccade latency, accuracy and dynamics, as well as the trial-to-trial variability of participants’ performance. RESULTS: Saccades of individuals with ASD were characterized by reduced accuracy, elevated variability in accuracy across trials, and reduced peak velocity and prolonged duration. In addition, their saccades took longer to accelerate to peak velocity, with no alteration in the duration of saccade deceleration. Gap/overlap effects on saccade latencies were similar across groups, suggesting that visual orienting and attention systems are relatively spared in ASD. Age-related changes did not differ across groups. CONCLUSIONS: Deficits precisely and consistently directing eye movements suggest impairment in the error-reducing function of the cerebellum in ASD. Atypical increases in the duration of movement acceleration combined with lower peak saccade velocities implicate pontine nuclei, specifically suggesting reduced excitatory activity in burst cells that drive saccades relative to inhibitory activity in omnipause cells that maintain stable fixation. Thus, our findings suggest that both cerebellar and brainstem abnormalities contribute to altered sensorimotor control in ASD. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/2040-2392-5-47) contains supplementary material, which is available to authorized users

Nitrogen Abundances in DLA Systems: The Combined Effects of SNII and SNIa in a Hierarchical Clustering Scenario

The combined enrichment of Supernovae II and I in a hierarchical clustering scenario could produce regions with low N content respect to $\alpha$-elements consistent with observed values measured in Damped Ly-$\alpha$ (DLAs). We have studied the formation of DLAs in a hierarchical clustering scenario under the hypothesis that the building blocks of current field galaxies could be part of the structures mapped by DLAs. In our models the effects of the non-linear evolution of the structure (which produces bursty star formation histories, gas infall, etc.) and the contributions of SNIa and SNII are found to be responsible of producing these N regions with respect to the $\alpha$-elements. Although SNIa are not main production sites for Si or O, because of the particular timing Consistently, we found the simulated low nitrogen DLAs to have sub-solar [Fe/H]. We show that low nitrogen DLAs have experienced important star formation activity in the past with higher efficiency than normal DLAs. Our chemical model suggests that SNIa play a relevant role in the determination of the abundance pattern of DLA and, that the observed low nitrogen DLA frequency could be explained taking into account the time-delay of $\approx$ 0.5 Gyr introduced by these supernova to release metals.Comment: 4 pages, 2 Postscript figures. Accepted for publication in MNRAS (pink pages