Prenatal cocaine exposure and prematurity: Neurodevelopmental growth

The consequences of prematurity and prenatal cocaine exposure on early neurobehavior and physical growth were examined longitudinally in a sample of 20 cocaine-exposed and 20 nonexposed preterm neonates. The magnitude of the difference in physical growth acceleration related to prenatal cocaine exposure increased with increasing birth gestational age, whereas growth rate differences in irritability decreased. In contrast, prenatal cocaine exposure, independent of prematurity, was related to reduced attention skills at 36 wks conceptional age and increased rates of neurobehavioral change. The effects of prenatal cocaine exposure differed with respect to the degree of prematurity, depending on the nature of the outcome examined, suggesting differing windows of vulnerability for different outcome domains. The usefulness of a developmental growth perspective was demonstrated

Comment on ``Measurement of the 3^3He mass diffusion coefficient in superfluid 4^4He over the 0.45--0.95 K temperature range

The role of 3He-3He collisions in our diffusion experiment is addressed and shown to not be relevant to the measurement of 3He diffusion against phonons in superfluid helium.Comment: Two pages, in Europhysics Letters forma

The effect of energetic electron precipitation on middle mesospheric night-time ozone during and after a moderate geomagnetic storm

Using a ground-based microwave radiometer at Troll Station, Antarctica (72°S, 2.5°E, L = 4.76), we have observed a decrease of 20–70% in the mesospheric ozone, coincident with increased nitric oxide, between 60 km and 75 km altitude associated with energetic electron precipitation (E > 30 keV) during a moderate geomagnetic storm (minimum Dst of −79 nT) in late July 2009. NOAA satellite data were used to identify the precipitating particles and to characterize their energy, spatial distribution and temporal variation over Antarctica during this isolated storm. Both the ozone decrease and nitric oxide increase initiate with the onset of the storm, and persist for several days after the precipitation ends, descending in the downward flow of the polar vortex. These combined data present a unique case study of the temporal and spatial morphology of chemical changes induced by electron precipitation during moderate geomagnetic storms, indicating that these commonplace events can cause significant effects on the middle mesospheric ozone distribution

Application of Resonance Perturbation Theory to Dynamics of Magnetization in Spin Systems Interacting with Local and Collective Bosonic Reservoirs

We apply our recently developed resonance perturbation theory to describe the dynamics of magnetization in paramagnetic spin systems interacting simultaneously with local and collective bosonic environments. We derive explicit expressions for the evolution of the reduced density matrix elements. This allows us to calculate explicitly the dynamics of the macroscopic magnetization, including characteristic relaxation and dephasing time-scales. We demonstrate that collective effects (i) do not influence the character of the relaxation processes but merely renormalize the relaxation times, and (ii) significantly modify the dephasing times, leading in some cases to a complicated (time inhomogeneous) dynamics of the transverse magnetization, governed by an effective time-dependent magnetic field

Measurement of the 3He mass diffusion coefficient in superfluid 4He over the 0.45-0.95 K temperature range

We have measured the mass diffusion coefficient D of 3He in superfluid 4He at temperatures lower than were previously possible. The experimental technique utilizes scintillation light produced when neutron react with 3He nuclei, and allows measurement of the 3He density integrated along the trajectory of a well-defined neutron beam. By measuring the change in 3He density near a heater as a function of applied heat current, we are able to infer values of D with 20% accuracy. At temperatures below 0.7 K and for concentrations of order 10^{-4} we find D=(2.0+2.4-1.2)T^-(6.5 -/+ 1.2) cm^2/s, in agreement with a theoretical approximation.Comment: 8 pages, 5 figures. Submitted to Europhysics Letters and prepared in that journal's forma

Mesospheric nitric oxide model from SCIAMACHY data

We present an empirical model for nitric oxide (NO) in the mesosphere (≈60–90&thinsp;km) derived from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartoghraphY) limb scan data. This work complements and extends the NOEM (Nitric Oxide Empirical Model; Marsh et al., 2004) and SANOMA (SMR Acquired Nitric Oxide Model Atmosphere; Kiviranta et al., 2018) empirical models in the lower thermosphere. The regression ansatz builds on the heritage of studies by Hendrickx et al. (2017) and the superposed epoch analysis by Sinnhuber et al. (2016) which estimate NO production from particle precipitation. Our model relates the daily (longitudinally) averaged NO number densities from SCIAMACHY (Bender et al., 2017b, a) as a function of geomagnetic latitude to the solar Lyman-α and the geomagnetic AE (auroral electrojet) indices. We use a non-linear regression model, incorporating a finite and seasonally varying lifetime for the geomagnetically induced NO. We estimate the parameters by finding the maximum posterior probability and calculate the parameter uncertainties using Markov chain Monte Carlo sampling. In addition to providing an estimate of the NO content in the mesosphere, the regression coefficients indicate regions where certain processes dominate.</p

Predictors of cognitive enhancement after training in preschoolers from diverse socioeconomic backgrounds

The association between socioeconomic status and child cognitive development, and the positive impact of interventions aimed at optimizing cognitive performance, are well-documented. However, few studies have examined how specific socio-environmental factors may moderate the impact of cognitive interventions among poor children. In the present study, we examined how such factors predicted cognitive trajectories during the preschool years, in two samples of children from Argentina, who participated in two cognitive training programs (CTPs) between the years 2002 and 2005: the School Intervention Program (SIP;N=745) and the Cognitive Training Program (CTP;N=333). In both programs children were trained weekly for 16 week sand tested before and after the intervention using a battery of tasks assessing several cogntive control processes (attention, inhibitory control, working memory, flexibility and planning). After applying mixed model analyses, we identified sets of socio-environmental predictors that were associated with higher levels of pre-intervention cognitive control performance and with increased improvement in cognitive control from pre- to post-intervention. Child age, housing conditions, social resources, parental occupation and family composition were associated with performance in specific cognitive domains at baseline. Housing conditions, social resources, parental occupation, family composition, maternal physical health, age, group (intervention/control) and the number of training sessions were related to improvements in specific cognitive skills from pre- to post-training

Microtesla MRI of the human brain combined with MEG

One of the challenges in functional brain imaging is integration of complementary imaging modalities, such as magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI). MEG, which uses highly sensitive superconducting quantum interference devices (SQUIDs) to directly measure magnetic fields of neuronal currents, cannot be combined with conventional high-field MRI in a single instrument. Indirect matching of MEG and MRI data leads to significant co-registration errors. A recently proposed imaging method - SQUID-based microtesla MRI - can be naturally combined with MEG in the same system to directly provide structural maps for MEG-localized sources. It enables easy and accurate integration of MEG and MRI/fMRI, because microtesla MR images can be precisely matched to structural images provided by high-field MRI and other techniques. Here we report the first images of the human brain by microtesla MRI, together with auditory MEG (functional) data, recorded using the same seven-channel SQUID system during the same imaging session. The images were acquired at 46 microtesla measurement field with pre-polarization at 30 mT. We also estimated transverse relaxation times for different tissues at microtesla fields. Our results demonstrate feasibility and potential of human brain imaging by microtesla MRI. They also show that two new types of imaging equipment - low-cost systems for anatomical MRI of the human brain at microtesla fields, and more advanced instruments for combined functional (MEG) and structural (microtesla MRI) brain imaging - are practical.Comment: 8 pages, 5 figures - accepted by JM

Elastic Scattering of Pions From the Three-nucleon System

We examine the scattering of charged pions from the trinucleon system at a pion energy of 180 MeV. The motivation for this study is the structure seen in the experimental angular distribution of back-angle scattering for pi+ 3He and pi- 3H but for neither pi- 3He nor pi+ 3H. We consider the addition of a double spin flip term to an optical model treatment and find that, though the contribution of this term is non-negligible at large angles for pi+ 3He and pi- 3H, it does not reproduce the structure seen in the experiment.Comment: 15 pages + 5 figure