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Evidence on long-term influences of maternal vitamin B12 deficiency or concentrations on infant cognition is limited. We examined associations between maternal plasma vitamin B12 and cognitive development in 24-month-old infants. Maternal plasma vitamin B12 concentrations were measured at 26–28 weeks’ gestation; infant cognitive development was assessed with the Bayley Scales of Infant and Toddler Development-III at 24 months, for 443 mother–infant pairs from the Growing Up in Singapore Towards Healthy Outcomes cohort. Linear regressions adjusted for key confounders examined associations of maternal vitamin B12 with cognitive, receptive and expressive language, fine and gross motor subscales. Co-occurrence of maternal vitamin B12 with folate or vitamin B6 insufficiencies on child’s cognition was explored. Average maternal plasma vitamin B12 concentrations was 220·5 ± 80·5 pmol/l; 15 % and 41 % of mothers were vitamin B12 deficient (<148 pmol/l) and insufficient (148–220·9 pmol/l), respectively. Infants of mothers with vitamin B12 deficiency had 0·42 (95 % CI −0·70, −0·14) sd lower cognitive scores, compared with infants of mothers with sufficient vitamin B12. Co-occurrence of maternal vitamins B12 and B6 insufficiencies was associated with 0·37 (95 % CI −0·69, −0·06) sd lower cognitive scores in infants compared with infants of mothers sufficient in both vitamins. No significant associations were observed with other subscales. Study findings suggest the possible need to ensure adequate vitamin B12 during pregnancy. The impact of co-occurrence of maternal B-vitamins insufficiencies on early cognitive development warrants further investigation.
Adolescence is a critical time point in the lifecourse. LifeLab is an educational intervention engaging adolescents in understanding Developmental Origins of Health and Disease (DOHaD) concepts and the impact of the early life environment on future health, benefitting both their long-term health and that of the next generation. We aimed to assess whether engaging adolescents with DOHaD concepts improves scientific literacy and whether engagement alone improves health behaviours.
Six schools were randomized, three to intervention and three to control. Outcome measures were changed in knowledge, and intended and actual behaviour in relation to diet and lifestyle. A total of 333 students completed baseline and follow-up questionnaires. At 12 months, intervention students showed greater understanding of DOHaD concepts. No sustained changes in behaviours were identified.
Adolescents’ engagement with DOHaD concepts can be improved and maintained over 12 months. Such engagement does not itself translate into behaviour change. The intervention has consequently been revised to include additional components beyond engagement alone.
The holotype partial skull of Agorophius pygmaeus (the monotypic form for both the genus Agorophius and the Family Agorophiidae) has been missing for approximately 140 years. Since the discovery of Agorophius pygmaeus, many additional taxa and specimens have been placed in the Family Agorophiidae, only to be reclassified and removed later. This has created confusion as to what is and what is not an agorophiid and a lack of clarity as to what characteristics delimit the Agorophiidae. A newly discovered skull of an agorophiid recently collected from an underwater cliff face of the Ashley River, South Carolina, USA, is assigned to Agorophius pygmaeus. It derives from the base of the Ashley Formation (early Oligocene). The new specimen consists of most of the skull and periotics, which are well preserved and described for the first time in an agorophiid. The new specimen provides an opportunity to diagnose the Agorophiidae and place the genus and species within the phylogenetic context of the early odontocete radiation in the Oligocene, along with other taxa such as the Ashleycetidae, Mirocetidae, Patriocetidae, Simocetidae, Waipatiidae, and Xenorophidae. Based on this new understanding, Agorophiidae are known with certainty only from the early Oligocene of South Carolina, with other undescribed, potential agorophiid specimens from the Oligocene of the North Pacific region (Japan, Mexico, and Washington State).
Chamber sampling is a common method for measuring nitrous oxide (N2O) emissions from agricultural soils. However, for grazed pastures, the patchy nature of urine deposition results in very high levels of spatial variability in N2O emissions. In the present study, the behaviour of the sample mean was examined by simulating a large number (9999) of random N2O chamber samples under different assumptions regarding the underlying N2O distribution. Using sample sizes of up to 100 chambers, the Central Limit Theorem did not apply. The distribution of the sample mean was always right-skewed with a standard deviation varying between 12·5 and 135% of the true mean. However, the arithmetic mean was an unbiased estimator and the mean of the sample mean distribution was close to the true mean of the simulated N2O distribution. The properties of the sample mean distribution (variance, skewness) were affected significantly by the assumed distribution of the emission factor, but not by distribution of the urine patch concentration. The geometric mean was also investigated as a potential alternative estimator. However, although its distribution had lower variance, it was also biased. Two methods for bias correcting the mean were investigated. These methods reduced the bias, but at the cost of increasing the variance. Neither of the bias-corrected estimators were consistently better than the arithmetic mean in terms of skewness and variance. To improve the estimation of N2O emissions from a grazed pasture using chambers, techniques need to be developed to identify urine patch and non-urine patch areas before sampling.
We have completed a Chandra snapshot survey of 54 radio jets that are extended on arcsec scales. These are associated with flat spectrum radio quasars spanning a redshift range z=0.3 to 2.1. X-ray emission is detected from the jet of approximately 60% of the sample objects. We assume minimum energy and apply conditions consistent with the original Felten-Morrison calculations in order to estimate the Lorentz factors and the apparent Doppler factors. This allows estimates of the enthalpy fluxes, which turn out to be comparable to the radiative luminosities.
The gut microbiota plays an important role in the development of the immune and gastrointestinal systems of infants. In the present study, we investigated whether increased salmon consumption during pregnancy, maternal weight gain during pregnancy or mode of infant feeding alter the markers of gut immune defence and inflammation. Women (n 123) who rarely ate oily fish were randomly assigned to continue consuming their habitual diet or to consume two 150 g portions of farmed salmon per week from 20 weeks of pregnancy to delivery. Faecal samples were collected from the mothers (n 75) at 38 weeks of gestation and from their infants (n 38) on days 7, 14, 28 and 84 post-partum. Fluorescence in situ hybridisation was used to determine faecal microbiota composition and ELISA to measure faecal secretory IgA (sIgA) and calprotectin concentrations. There was no effect of salmon consumption on maternal faecal microbiota or on maternal or infant faecal sIgA and calprotectin concentrations. The degree of weight gain influenced maternal faecal microbiota, and the mode of infant feeding influenced infant faecal microbiota. Faecal samples collected from infants in the salmon group tended to have lower bacterial counts of the Atopobium cluster compared with those collected from infants in the control group (P= 0·097). This difference was significant in the formula-fed infants (P< 0·05), but not in the exclusively breast-fed infants. In conclusion, the impact of oily fish consumption during pregnancy on maternal and infant gut microbiota composition is limited, but significant differences are associated with maternal weight gain during pregnancy and mode of infant feeding.
Decreased productivity on verbal fluency tasks by persons with schizophrenia has been attributed to semantic system abnormalities. Semantic structure is often assessed using multidimensional scaling (MDS) to detect normal and aberrant semantic clustering. However, MDS has limitations that may be particularly problematic for such assessments. Here, we introduce a different clustering technique, singular value decomposition (SVD), to elucidate abnormalities of the semantic system in schizophrenia. We compared 102 treated outpatients with schizophrenia to 109 healthy adults on two category-cued word fluency tasks. Patients with schizophrenia showed semantic clustering patterns that differ markedly from those of healthy adults. However, SVD revealed more detailed and critical semantic system abnormalities than previously appreciated using MDS. Patients with schizophrenia showed less coherent semantic clustering of both low- and high-frequency category exemplars than healthy adults. These results suggest the intriguing possibility that impaired automatic activation of semantic information is a key deficit in schizophrenia. (JINS, 2012, 18, 565–575)
The formation of silicon-on-insulator structures, by recrystallising polycrystalline silicon films with a dual electron beam technique, has been studied over a wide range of conditions. The quality of the layers has been assessed by examining cross-sections in the SEM and optical microscopy of the surface after a Secco etch. The range of line powers which gives device-worthy single crystal material becomes greater as the sweep speed increases and as the background temperature is reduced. The extent of melting into the substrate in the seed windows and below the isolating oxide was determined from the movement of an arsenic implant. The experimental results are compared to the predictions from a one dimensional model for the heat flow.
The 2-dimensional electron gas (2DEG) in an Al0.6Ga0.4Sb/InAs single quantum well (SQW) is studied using cyclotron resonance (CR) and Shubnikov - de Haas (SdH) techniques. SdH results show spin-splitting in Landau levels at magnetic field strength (B) as low as 1.5T. The effective mass (m*) of the 2DEG was obtained from the peak positions of the CR transmission spectra. The results exhibit oscillatory behavior as a function of B. The m* value extracted from die temperature dependence of the SdH oscillations is in good agreement with the average value of m* obtained from CR measurements. The effective mass is calculated as a function of B using an electron self-energy model based on the Hartree-Fock approximation. The calculated m* values also show oscillatory behavior similar to that of the measured CR m*. Both experiment and theory show that m* maxima are shifted from the integral values (both odd and even) of the filling factors.
The diffusion and activation of implanted boron in silicon during rapid thermal annealing (RTA) has been studied using the analytical techniques of SIMS, TEM, and sheet resistance measurements. Both crystalline and pre-amorphised silicon substrates were investigated. Data analysis in conjunction with a range of numerical models indicates some novel features of boron RTA, as well as accounting for previously observed features. In particular, a large transient diffusion enhancement coupled with an increase of electrical activity, are seen at short anneal times, in the case of crystalline silicon substrates. A non-equilibrium diffusion enhancement of a different type is also seen at much longer times, in both crystalline and pre-amorphised samples implanted to high doses. This second enhancement persists after all the precipitated boron formed on implantation has become substitutional. TEM studies show that the transient enhancement may be associated with the evolution of extended defect structures during the early stages of annealing. Both types of enhancement can be well represented by multiplying the ‘normal’ concentration-dependent diffusivity (with β=0.5) by a factor f>1.
A dual electron beam machine has been used to anneal boron implanted layers in order to study the diffusion and activation behaviour over a wide range of doses. The annealed implants have been characterized by spreading resistance profiling and secondary ion mass spectroscopy (SIMS). Carrier concentration profiles show that millisecond duration anneals can activate boron implants. A boron dose of 1E16 ions/cm2 was annealed to give a sheet resistance of 30 Ωsq with 40% of the implant activated. The SIMS technique showed there were no significant differences between the atomic profiles of the as-implanted samples and specimens subjected to a millisecond anneal or to a low temperature 850°C rapid isothermal anneal for 10s.
The annealing behaviour of B implants in the millisecond time regime using a
combination of swept line beam and background heating is compared with
isothermal annealing with heating cycles of a few seconds. Carrier
concentration profiles derived from spreading resistance measurements show
that under annealing conditions which restrict diffusion, millisecond
processing gives higher activation of B implants than isothermal heating.
Transmission electron microscopy shows that millisecond annealing also
results in a lower defect density than that following an equivalent
The annealing and diffusion behaviour of ion implanted boron over a wide range of doses in as-received and pre-amorphised silicon (180 keV 5 × 1015 cm−2 silicon implants) has been studied using conventional furnace annealing and multiple scan electron beam heating in the rapid isothermal annealing mode. The layers obtained have been characterised using spreading resistance profiling (SRP), SIMS and TEM.
For furnace annealing the silicon implantation produces improved electrical activation for boron doses in excess of 1015 cm−2. SIMS and SRP data indicate that a higher level of peak activation has been achieved, whilst the overall amount of redistribution has been restricted. The reduction in diffusion achieved (∼0.2 μm) is greater than the maximum difference attributable to the effect of lower ion channelling for the silicon implanted samples. Cross-sectional TEM has been used to determine the resulting defect structure and provides insight into the details of the stable precipitated boron surface peak observed. A numerical diffusion model has been developed to allow interpretation of these experimental findings.
Similar samples have been annealed using multiple scan electron beam heating (peak temperatures up to 1100°C for times up to 300 s). For silicon implanted with boron alone, where cooling commenced once the peak temperature of 1100°C had been reached, diffusion was restricted to 0.05 μm while the sheet resistance (32 Ω/square) was reduced by ∼25% compared to furnace anneals at 950°C. Identical annealing of silicon implanted samples produced improved activation with a sheet resistance of 26 Ω/square. Results from SIMS, SRP and TEM analysis of these experiments are reported.
The amorphous silicon memory device shows promise as an analogue weight element in neural networks. The device resistance can be programmed to within 5% of any specific value between lkΩ and lMΩ using 10ns to 1μ voltage pulses in the range 1–5V. In this paper we describe the physical structure of the element and its electrical characteristics. Finally, a simple example is discussed of a small neural network implementing the EXOR function using amorphous silicon memory elements as a resistive array of weights and external op-amps as the current summing nodes.
We present electric-field dependent electroreflectance and photocurrent spectra of visible-bandgap Inx(AlyGa1-y)1-xP/Inx’(Aly’Ga1-y’)1-x’P multiple-quantum-well (MQW) structures. These structures, grown by metal-organic vapor phase epitaxy on 6°-misoriented (100) GaAs substrates, have undoped MQWs sandwiched between doped Ino 5AI0.5P layers, forming p-i-n diodes. Quantum-well compositions in the range 0.46≤x≤0.52 and 0≤y≤0.4, corresponding to bandgaps in the red to yellow range, were used. The Stark shifts in these various samples were measured and found to depend on the details of the Mg p-type doping profile, confirming important diffusion effects, in agreement with secondary ion mass spectrometry and capacitance-voltage data. Our results show that these new materials are promising for visible-wavelength optical modulator applications.
The response of a range of porous Si and poly Si films to storage in acellular simulated body fluids is summarised and its implications discussed. It is suggested that the combination of VLSI technology, micromachining and surface microstructuring achievable with silicon, could establish this prominent semiconductor as a very useful biomaterial by the next century. The ‘biocompatibility’ of a variety of silicon microstructures, and even bulk silicon has received surprisingly little study, but now warrants detailed in-vitro and in-vivo assessment.
A variety of polymer materials including polyimide (PI), polyarylate (PAR), polynorbonene (PNB) and polyethersulphone (PES) have been studied for use as substrates in the formation of active matrix displays based upon polycrystalline silicon (poly-Si) thin film transistors (TFTs). A process used to fabricate transflective mobile phone displays at 250°C on such substrates is described in detail. The NMOS TFTs show a mobility of 100cm2/Vs, and a threshold voltage of 3.9V; the PMOS devices have a mobility of 52cm2/Vs, and a threshold voltage of -6V. Issues relating to performance of these devices, yield of the arrays, and manufacturability are discussed.
Regression-based normative techniques account for variability in test performance associated with multiple predictor variables and generate expected scores based on algebraic equations. Using this approach, we show that estimated IQ, based on oral word reading, accounts for 1–9% of the variability beyond that explained by individual differences in age, sex, race, and years of education for most cognitive measures. These results confirm that adding estimated “premorbid” IQ to demographic predictors in multiple regression models can incrementally improve the accuracy with which regression-based norms (RBNs) benchmark expected neuropsychological test performance in healthy adults. It remains to be seen whether the incremental variance in test performance explained by estimated “premorbid” IQ translates to improved diagnostic accuracy in patient samples. We describe these methods, and illustrate the step-by-step application of RBNs with two cases. We also discuss the rationale, assumptions, and caveats of this approach. More broadly, we note that adjusting test scores for age and other characteristics might actually decrease the accuracy with which test performance predicts absolute criteria, such as the ability to drive or live independently. (JINS, 2009, 15, 1012–1022.)
Synaptic development and elimination are normal neurodevelopmental processes, which if altered could contribute to various neuropsychiatric disorders. 31P-1H magnetic resonance spectroscopic imaging (MRSI) and structural magnetic resonance imaging (MRI) exams were conducted on 105 healthy children ages 6–18 years old to identify neuromolecular indices of synaptic development and elimination. Over the age range studied, age-related changes in high-energy phosphate (phosphocreatine), membrane phospholipid metabolism (precursors and breakdown products), and percent gray matter volume were found. These neuromolecular and structural indices of synaptic development and elimination are associated with development of several cognitive domains. Monitoring of these molecular markers is essential for devising treatment strategies for neurodevelopmental disorders. (JINS, 2009, 15, 671–683.)