Stability and collapse of localized solutions of the controlled three-dimensional Gross-Pitaevskii equation

On the basis of recent investigations, a newly developed analytical procedure is used for constructing a wide class of localized solutions of the controlled three-dimensional (3D) Gross-Pitaevskii equation (GPE) that governs the dynamics of Bose-Einstein condensates (BECs). The controlled 3D GPE is decomposed into a two-dimensional (2D) linear Schr\"{o}dinger equation and a one-dimensional (1D) nonlinear Schr\"{o}dinger equation, constrained by a variational condition for the controlling potential. Then, the above class of localized solutions are constructed as the product of the solutions of the transverse and longitudinal equations. On the basis of these exact 3D analytical solutions, a stability analysis is carried out, focusing our attention on the physical conditions for having collapsing or non-collapsing solutions.Comment: 21 pages, 14 figure

Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes

postprin

The genetic architecture of the human cerebral cortex

INTRODUCTION The cerebral cortex underlies our complex cognitive capabilities. Variations in human cortical surface area and thickness are associated with neurological, psychological, and behavioral traits and can be measured in vivo by magnetic resonance imaging (MRI). Studies in model organisms have identified genes that influence cortical structure, but little is known about common genetic variants that affect human cortical structure. RATIONALE To identify genetic variants associated with human cortical structure at both global and regional levels, we conducted a genome-wide association meta-analysis of brain MRI data from 51,665 individuals across 60 cohorts. We analyzed the surface area and average thickness of the whole cortex and 34 cortical regions with known functional specializations. RESULTS We identified 306 nominally genome-wide significant loci (P < 5 × 10−8) associated with cortical structure in a discovery sample of 33,992 participants of European ancestry. Of the 299 loci for which replication data were available, 241 loci influencing surface area and 14 influencing thickness remained significant after replication, with 199 loci passing multiple testing correction (P < 8.3 × 10−10; 187 influencing surface area and 12 influencing thickness). Common genetic variants explained 34% (SE = 3%) of the variation in total surface area and 26% (SE = 2%) in average thickness; surface area and thickness showed a negative genetic correlation (rG = −0.32, SE = 0.05, P = 6.5 × 10−12), which suggests that genetic influences have opposing effects on surface area and thickness. Bioinformatic analyses showed that total surface area is influenced by genetic variants that alter gene regulatory activity in neural progenitor cells during fetal development. By contrast, average thickness is influenced by active regulatory elements in adult brain samples, which may reflect processes that occur after mid-fetal development, such as myelination, branching, or pruning. When considered together, these results support the radial unit hypothesis that different developmental mechanisms promote surface area expansion and increases in thickness. To identify specific genetic influences on individual cortical regions, we controlled for global measures (total surface area or average thickness) in the regional analyses. After multiple testing correction, we identified 175 loci that influence regional surface area and 10 that influence regional thickness. Loci that affect regional surface area cluster near genes involved in the Wnt signaling pathway, which is known to influence areal identity. We observed significant positive genetic correlations and evidence of bidirectional causation of total surface area with both general cognitive functioning and educational attainment. We found additional positive genetic correlations between total surface area and Parkinson’s disease but did not find evidence of causation. Negative genetic correlations were evident between total surface area and insomnia, attention deficit hyperactivity disorder, depressive symptoms, major depressive disorder, and neuroticism. CONCLUSION This large-scale collaborative work enhances our understanding of the genetic architecture of the human cerebral cortex and its regional patterning. The highly polygenic architecture of the cortex suggests that distinct genes are involved in the development of specific cortical areas. Moreover, we find evidence that brain structure is a key phenotype along the causal pathway that leads from genetic variation to differences in general cognitive function

Track D Social Science, Human Rights and Political Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd

Impact damage detection in carbon fibre composites using HTS SQUIDs and neural networks

A neural network-based data analysis tool, developed to speed the damage detection process for the NDE of impact damaged carbon fibre composites, is discussed. A feature extraction method utilising a gradient threshold search function and a feed forward neural network for pattern recognition were used to develop the system. Impact damaged carbon composite sample plates were scanned with an eddy current-based NDE setup using HTS SQUID gradiometers and double-D excitation coils. Detection of damage sites in data affected by noise spikes caused by environmental disturbances is demonstrated. Finally, a possible design for a future entirely automated scanning system is also introduced

Squid-based nondestructive evaluation of carbon fiber reinforced polymer

Recent work with HTS SQUIDs in nondestructive evaluation has concentrated on the detection of flaws in aircraft-grade aluminum, with particular emphasis on surface-breaking tears beside rivets. More complex materials are now also being used in aircraft manufacture, with carbon fiber reinforced polymer (CFRP) being one of the most common. Existing technologies such as ultrasound are particularly well suited to the detection of impact-damaged sites and until now there have only been a few reports of eddy current examination of CFRP samples. Here we present results on samples with regions of heat damage, impact damage and with nonmagnetic inserts using eddy current detection techniques. We compare the signal to noise ratio and spatial resolution for a variety of sensors including HTS SQUIDs and gradiometers and conventional induction coils, and discuss variations in detection efficiency with field component measured

Electronic gradiometry for NDE in an unshielded environment with stationary and moving HTS SQUIDs

Difficulties in the fabrication of multilayer high-temperature superconductor (HTS) devices have led to recent interest in the use of simpler HTS SQUID magnetometers in electronic gradiometers. One application of such systems is electromagnetic non-destructive evaluation. We have developed a prototype two-SQUID system and we present recent results in this paper. We first demonstrate the level of interference suppression by comparing magnetometer and gradiometer signals. Then we present several results taken conventionally with the HTS SQUIDs stationary above moving specimens and, for the first time, with the SQUIDs unshielded in motion above stationary specimens. The specimens comprise a pair of wires in a return current loop as a calibration source, and an aircraft-grade aluminium plate with fine slits mimicking fatigue cracks, first exposed and then covered with an additional aluminium sheet to simulate internal flaws. These results are an important, though by no means final, step towards practical non-destructive evaluation of real test subjects with HTS SQUIDs

Electromagnetic nondestructive evaluation with simple HTS SQUIDs: measurements and modelling

For AC EM NDE research, the field sensitivity of a SQUID should be around 100 pT, in a bandwidth of 5 Hz or less in the frequency range from 1 Hz to 10 kHz or more. Existing HTS SQUIDs and commercial electronics can already satisfy these demands. Moreover, the small size of HTS SQUIDs and the large dynamic range of SQUID systems permit measurements even in some magnetically unshielded environments. Here, we describe non-contacting AC EM NDE with a simple, small, single layer HTS SQUID. We present results demonstrating the detection of a subsurface feature in aircraft-grade aluminium by horizontal field measurement. Although they indicate the potential usefulness of HTS SQUIDs, variation between nominally identical data has been much greater than expected. This is because of fundamental HTS SQUID problems and the fact that experimental constraints on SQUID position, induction coil geometry and stand-off led to a far from optimum system design. We have analysed the problem using FEM; here we present selected results and indicate how they may affect future designs

Electromagnetic nondestructive evaluation: moving HTS SQUIDs, inducing field nulling and dual frequency measurements

We have previously shown that simple, single layer HTS SQUIDs can be used effectively in electromagnetic nondestructive evaluation (NDE) using eddy current techniques in a magnetically unshielded environment. HTS SQUID systems for NDE applications are expected to be small and portable allowing non-stationary measurements to be carried out in the Earth's field above a stationary sample. Here we present application-oriented results showing the ability of our HTS electronic gradiometer to cope with the movement of the sensors above a series of simulated flaws in aircraft grade aluminum samples. To permit the detection of fine surface and subsurface structures we have applied active field nulling to the two SQUIDs to increase the effective signal to noise ratio. The excitation signal is applied via a non-superconducting coil to provide a lower field environment for each device. We also present results using a dual frequency eddy current technique to allow depth profiling of flaws in multilayer structures