The Developmental Chronnecto-Genomics (Dev-CoG) study: A multimodal study on the developing brain.

Brain development has largely been studied through unimodal analysis of neuroimaging data, providing independent results for structural and functional data. However, structure clearly impacts function and vice versa, pointing to the need for performing multimodal data collection and analysis to improve our understanding of brain development, and to further inform models of typical and atypical brain development across the lifespan. Ultimately, such models should also incorporate genetic and epigenetic mechanisms underlying brain structure and function, although currently this area is poorly specified. To this end, we are reporting here a multi-site, multi-modal dataset that captures cognitive function, brain structure and function, and genetic and epigenetic measures to better quantify the factors that influence brain development in children originally aged 9-14 years. Data collection for the Developmental Chronnecto-Genomics (Dev-CoG) study (http://devcog.mrn.org/) includes cognitive, emotional, and social performance scales, structural and functional MRI, diffusion MRI, magnetoencephalography (MEG), and saliva collection for DNA analysis of single nucleotide polymorphisms (SNPs) and DNA methylation patterns. Across two sites (The Mind Research Network and the University of Nebraska Medical Center), data from over 200 participants were collected and these children were re-tested annually for at least 3 years. The data collection protocol, sample demographics, and data quality measures for the dataset are presented here. The sample will be made freely available through the collaborative informatics and neuroimaging suite (COINS) database at the conclusion of the study.

Multi-directional beam steering using diffractive neural networks.

The modern-day resurgence of machine learning has encouraged researchers to revisit older problem spaces from a new perspective. One promising avenue has been implementing deep neural networks to aid in the simulation of physical systems. In the field of optics, densely connected neural networks able to mimic wave propagation have recently been constructed. These diffractive deep neural networks (D2NN) not only offer new insights into wave propagation, but provide a novel tool for investigating and discovering multi-functional diffractive elements. In this paper, we derive an efficient GPU-friendly D2NN methodology based on Rayleigh-Sommerfeld diffraction. We then use the implementation to virtually forge cascades of optical phase masks subject to different beam steering conditions. The input and output conditions we use to train each D2NN instance is based on commercial electro-optic modulated waveguide systems to encourage experimental follow-on. In total, we analyze the beam steering efficacy of 27 individual D2NN instances which explore different permutations of input sources, mask cascades, and output steering targets.

Artificial neural network discovery of a switchable metasurface reflector.

Optical materials engineered to dynamically and selectively manipulate electromagnetic waves are essential to the future of modern optical systems. In this paper, we simulate various metasurface configurations consisting of periodic 1D bars or 2D pillars made of the ternary phase change material Ge2Sb2Te5 (GST). Dynamic switching behavior in reflectance is exploited due to a drastic refractive index change between the crystalline and amorphous states of GST. Selectivity in the reflection and transmission spectra is manipulated by tailoring the geometrical parameters of the metasurface. Due to the immense number of possible metasurface configurations, we train deep neural networks capable of exploring all possible designs within the working parameter space. The data requirements, predictive accuracy, and robustness of these neural networks are benchmarked against a ground truth by varying quality and quantity of training data. After ensuring trustworthy neural network advisory, we identify and validate optimal GST metasurface configurations best suited as dynamic switchable mirrors depending on selected light and manufacturing constraints.

Spectrally tunable chiral Bragg reflectors for on-demand beam generation.

We demonstrate the generation of spectrally tunable phase-dependent wavefronts, using the 2D Airy as the primary test case, via a polymer-stabilized cholesteric liquid crystal (PSCLC) element. Specifically, we use a novel spatial light modulator (SLM) based projection system to photo-align the initial helix angle landscape of the PSCLC so that it imparts the appropriate cubic phase profile to the reflected beam. This element is spectrally selective, with a reflection bandwidth of ≈ 100 nm, and electrically tunable from λ = 530 nm to 760 nm. Under both green and red laser illumination, the element is shown to conditionally form an Airy beam depending on the position of the electrically tailored reflection band. We briefly demonstrate the generality of this approach by producing PSCLC elements which form a computer-generated hologram and a higher-order Mathieu beam.

Versatile supercontinuum generation in parabolic multimode optical fibers.

We demonstrate that the pump's spatial input profile can provide additional degrees of freedom in tailoring at will the nonlinear dynamics and the ensuing spectral content of supercontinuum generation in highly multimoded optical fibers. Experiments and simulations carried out at 1550 nm indicate that the modal composition of the input beam can substantially alter the soliton fission process as well as the resulting Raman and dispersive wave generation that eventually lead to supercontinuum in such a multimode environment. Given the multitude of conceivable initial conditions, our results suggest that it is possible to pre-engineer the supercontinuum spectral content in a versatile manner.

Dressed optical filaments.

In this Letter we show that by appropriately providing an auxiliary "dress" beam one can extend the longevity of an optical filament by almost one order of magnitude. These optical dressed filaments can propagate substantially further by judiciously harnessing energy from their secondary beam reservoir. This possibility is theoretically investigated in air when the filament is dressed with a conically convergent annular Gaussian beam.

Propagation of Gaussian-apodized paraxial beams through first-order optical systems via complex coordinate transforms and ray transfer matrices.

We investigate the linear propagation of Gaussian-apodized solutions to the paraxial wave equation in free-space and first-order optical systems. In particular, we present complex coordinate transformations that yield a very general and efficient method to apply a Gaussian apodization (possibly with initial phase curvature) to a solution of the paraxial wave equation. Moreover, we show how this method can be extended from free space to describe propagation behavior through nonimaging first-order optical systems by combining our coordinate transform approach with ray transfer matrix methods. Our framework includes several classes of interesting beams that are important in applications as special cases. Among these are, for example, the Bessel-Gauss and the Airy-Gauss beams, which are of strong interest to researchers and practitioners in various fields.

Women's attitudes towards management of breech presentation at term.

Current advice on the management of breech presentation at term is that all uncomplicated cases should be offered external cephalic version (ECV) or an elective caesarean section. Clinical experience suggests that ECV is currently not offered as widely as advised and that the majority are delivered electively by caesarean section. We present the results of a patient attitude survey of term breech deliveries in a university teaching hospital over 12 months. The results show that half of respondents were not offered ECV and that two-thirds of these women were not eligible for ECV, either having had a previous caesarean or breech presentation diagnosed in labour. One-third of women, potentially suitable for ECV, were not made aware of their options. The majority are offered elective caesarean section with a small minority (10%) opting for planned vaginal breech delivery.

Degradation of herbicides in shallow Danish aquifers: an integrated laboratory and field study.

Degradation of pesticides in aquifers has been evaluated based on a number of co-ordinated field and laboratory studies carried out in Danish aquifers. These studies included investigations of vertical and horizontal variability in degradation rates from the vadose zone to an aquifer, the effects of aerobic versus anaerobic conditions, and the importance of concentration on degradation kinetics for a selected range of herbicides. The studies were based on different experimental approaches ranging from simple batch experiments to column studies to field injection experiments and, where appropriate, results were compared. Some herbicides were degraded under aerobic conditions (some phenoxy acids, DNOC and glyphosate) and others under aerobic conditions (other phenoxy acids, DNOC; there was some indication of atrazine transformation). Certain pesticides were not degraded in any investigations (dichlobenil, the dichlobenil metabolite 2,6-dichlorobenzamide (BAM), bentazone, isoproturon, metamitron and metsulfuron-methyl). The spatial variability was substantial, since hardly any of the investigated pesticides were degraded in all comparable samples. This means that it is very difficult to claim that a given pesticide is readily degradable in aquifers. However, the experimental approaches used (with incubations lasting more than a year) may not be sensitive enough to verify the low degradation rates that may be significant as a result of the long retention time of groundwaters.

Quantification of acetochlor degradation in the unsaturated zone using two novel in situ field techniques: comparisons with laboratory-generated data and implications for groundwater risk assessments.

Degradation of the herbicide acetochlor in the unsaturated zone was quantified using two unique in situ field techniques. The DT50 values generated at two different sites on surface soil and two subsoil depths using these techniques were compared with values generated under aerobic laboratory-incubation conditions (typically 20 degrees C, 40% maximum water holding capacity). Additionally, laboratory-degradation data were generated on surface and subsoils from four other sites. All subsoils were treated with acetochlor at 5% of the surface soil application rate. Acetochlor degradation in both field- and laboratory-incubated subsoils was rapid and often exceeded surface soil rates. Field and laboratory DT50 values from all sites ranged from 2 to 88 days in subsoil, compared with a range of 1 to 18 days in surface soils. The DT50 results from in situ field techniques were comparable with those generated from laboratory incubations in the same soils, confirming the validity of performing laboratory-based degradation studies to determine pesticide DT50 values in subsoils. Microbiological characterisation of selected soils revealed that subsoils had a viable and active population, although direct counts of bacteria were consistently lower in subsoil (10(8)-10(9) g-1 dry soil) compared with surface soils (10(10) g-1 dry soil). The leaching models used to perform groundwater risk assessments (e.g. PELMO, PESTLA, MACRO-DB, PRZM and the FOCUS EU leaching scenarios) have provision for inclusion of subsoil degradation rates. However, conservative default estimates are typically used, as no other alternative is available. Results presented here show that these default values may significantly underestimate true subsoil degradation contributions, and therefore not accurately predict pesticide concentrations in groundwater. The degradation data generated for acetochlor were applied to the mathematical model PELMO to demonstrate the importance of the inclusion of subsoil degradation data in groundwater risk assessment models and thereby in the registration of pesticides in Europe.

Randomized study of intravenous fluid preload before epidural analgesia during labour.

We performed a randomized controlled trial of the effect of intravenous fluid preload on maternal hypotension and fetal heart rate (FHR) changes in labour after the first epidural injection. Group 1 (49 women) received 1 litre of crystalloid preload. Group 2 (46 women) received no preload. No statistically significant difference was shown between the two groups for either of the outcomes. Hypotension was found in three women in group 1 and five in group 2 (P = 0.4). Deterioration in FHR pattern was found in four women in group 1 and 11 in group 2 (P = 0.08). This study has not shown a significant increase in the incidence of hypotension when intravenous preload is omitted before epidural analgesia using a low concentration of bupivacaine during labour. Because of the clinical importance of the difference in the rate of FHR deterioration between the two groups, we continue to administer preload for high-risk cases.

Infusion clearance of subcutaneous iothalamate versus standard renal clearance.

Accurate, timed urine collections for the measurement of glomerular filtration rate (GFR) may be impractical in infants or in patients with urological abnormalities. GFR may be measured without urine collection using a constant subcutaneous infusion of iothalamate. We compare the infusion clearance with conventional renal clearance in 14 children and young adults. The mean clearance ratio (infusion clearance/renal clearance +/- 1 SD) was 0.99 +/- 0.1 and the mean discrepancy between the two methods was 8.5% +/- 4.7%. The 95% limits of agreement for the ratio of the two methods are 0.83-1.23. These data indicate that subcutaneous infusion of iothalamate is a practical method for measuring GFR in children without a urine collection.

Expectations of assisted conception for infertility.

OBJECTIVE: To provide reliable prognostic information for couples seeking assisted conception. DESIGN: Analysis of four years' practice (1988-91). SETTING: Private university service linked with NHS reproductive medicine services. PATIENTS: 804 couples with various causes of subfertility, median duration five years, median age of women 34 years. INTERVENTIONS: 1280 completed cycles: 950 in vitro fertilisation, 144 gamete intrafallopian transfer, and 186 intrauterine insemination and superovulation. MAIN OUTCOME MEASURES: Pregnancy and birth rates per cycle and cumulative pregnancy and take home baby rates per couple. RESULTS: In women under 40 years and men with normal sperm, whatever the cause of infertility, results with in vitro fertilisation improved steadily reaching a pregnancy rate per cycle of 30% (95% confidence interval 26% to 35%) during 1990-1 and birth rate per cycle of 29% (23% to 35%) in 1990. Pregnancy and birth rates for gamete intrafallopian transfer were 36% (28% to 44%) and 26% (17% to 37%) and for intrauterine insemination 18% (12% to 24%) and 16% (10% to 22%). After six cycles cumulative probability of pregnancy was 82% and cumulative take home baby rate 70%. Considering only in vitro fertilisation and gamete intrafallopian transfer after four cycles the pregnancy rate was 78% (66% to 91%). CONCLUSIONS: Conception is less likely in women over 40 and men with sperm dysfunction. For other couples the prognosis for a live birth is at least as good as for fertile couples if they persist with treatment.

A prospective controlled study of in-vitro fertilization, gamete intra-fallopian transfer and intrauterine insemination combined with superovulation.

The relative effectiveness of in-vitro fertilization (IVF), gamete intra-Fallopian transfer (GIFT) and intrauterine insemination (IUI) combined with superovulation in the treatment of infertility were compared in 151 couples undergoing a single cycle of treatment. Treatment was selected as appropriate (IVF for tubal disease, GIFT or IUI/superovulation for nontubal infertility) but possible bias due to non-randomization was overcome by all couples having had favourable fertilization in a previous cycle of IVF. Furthermore, in a preliminary study of initial IVF treatment in 265 couples from whom the study patients were drawn, implantation and pregnancy rates in the diagnostic groups were similar. In the definitive study comparing IVF, GIFT and IUI/superovulation, the pregnancy rate observed with GIFT was highest (40%) but this was not significantly higher than with IVF (28%) or IUI/superovulation (20%). However, the implantation rate per egg transferred by GIFT (21%) was significantly higher than the implantation rate per embryo transferred by IVF (11%). Although the pregnancy rates with GIFT were not statistically greater than with IVF, a significant advantage is likely to be observed in larger groups in view of the better implantation rate. The lower pregnancy rates with IUI superovulation are to be expected because of limited ovarian stimulation, they are nevertheless of comparative interest.

Subclavian vein thrombosis: a late complication of ovarian hyperstimulation syndrome.

Two cases of subclavian vein thrombosis following ovarian stimulation for in-vitro fertilization and subsequent ovarian hyperstimulation syndrome (OHSS) are described. Both occurred several weeks after complete resolution of the OHSS. The site of the lesions and their timing suggest that there is a generalized disturbance of coagulation associated with OHSS, which persists beyond the duration of the clinical syndrome.