InGaN µLEDs integrated onto colloidal quantum dot functionalized ultra-thin glass.

Red-, orange-, and green-emitting integrated optoelectronic sources are demonstrated by transfer printing blue InGaN µLEDs onto ultra-thin glass platforms functionally enhanced with II-VI colloidal quantum dots (CQDs). The forward optical power conversion efficiency of these heterogeneously integrated devices is, respectively, 9%, 15%, and 14% for a blue light absorption over 95%. The sources are demonstrated in an orthogonal frequency division multiplexed (OFDM) visible light communication link reaching respective data transmission rates of 46 Mbps, 44 Mbps and 61 Mbps.

Heterogeneous integration of gallium nitride light-emitting diodes on diamond and silica by transfer printing.

We report the transfer printing of blue-emitting micron-scale light-emitting diodes (micro-LEDs) onto fused silica and diamond substrates without the use of intermediary adhesion layers. A consistent Van der Waals bond was achieved via liquid capillary action, despite curvature of the LED membranes following release from their native silicon growth substrates. The excellence of diamond as a heat-spreader allowed the printed membrane LEDs to achieve optical power output density of 10 W/cm(2) when operated at a current density of 254 A/cm(2). This high-current-density operation enabled optical data transmission from the LEDs at 400 Mbit/s.

Prospects of III-nitride optoelectronics grown on Si.

The use of III-nitride-based light-emitting diodes (LEDs) is now widespread in applications such as indicator lamps, display panels, backlighting for liquid-crystal display TVs and computer screens, traffic lights, etc. To meet the huge market demand and lower the manufacturing cost, the LED industry is moving fast from 2 inch to 4 inch and recently to 6 inch wafer sizes. Although Al2O3 (sapphire) and SiC remain the dominant substrate materials for the epitaxy of nitride LEDs, the use of large Si substrates attracts great interest because Si wafers are readily available in large diameters at low cost. In addition, such wafers are compatible with existing processing lines for 6 inch and larger wafers commonly used in the electronics industry. During the last decade, much exciting progress has been achieved in improving the performance of GaN-on-Si devices. In this contribution, the status and prospects of III-nitride optoelectronics grown on Si substrates are reviewed. The issues involved in the growth of GaN-based LED structures on Si and possible solutions are outlined, together with a brief introduction to some novel in situ and ex situ monitoring/characterization tools, which are especially useful for the growth of GaN-on-Si structures.

Emotions and eating. Self-reported and experimentally induced changes in food intake under stress.

Two studies investigated the stress-eating relationship. The first examined self-reported changes in intake of snack foods, whilst the second investigated stress-induced overconsumption in a laboratory setting comparing high (HF) and low-fat (LF) snacks. Eighty-nine females completed the Dutch Eating Behaviour Questionnaire (DEBQ) [Van Strien, T., Fritjers, J. E. R., Bergers, G. P. A., & Defares, P. B. (1986). Dutch Eating Behaviour Questionnaire for assessment of restrained, emotional and external eating behaviour. International Journal of Eating Disorders, 5, 295-315] and a self-report measure designed to evaluate changes in eating in response to stress. Increased intake of HF snacks was associated with high emotional eating but not with restraint. A laboratory-based experiment compared intake of HF and LF snacks after ego-threatening and neutral Stroop colour-naming tasks. Intake was suppressed by 31.8% in restrained compared to unrestrained eaters across tasks. Restrained eaters consumed significantly less after ego-threat than after the neutral manipulation, but this was associated only with intake of the LF snack. Restrained eaters' intake of dried fruit was suppressed by 33.2% after ego-threat relative to the neutral task, despite a significant increase in hunger for this group following ego-threat. These results suggest that the type and variety of foods offered influences the link between stress and eating in laboratory settings. Further research should aim to replicate and extend these findings, with a view to informing potential interventions for stress-related eating.

Childhood obesity and socioeconomic status: a novel role for height growth limitation.

OBJECTIVE: To assess prevalence and socioeconomic context of overweight and obesity in a cohort of Scottish children. DESIGN: Cross-sectional study. SETTING: Primary schools in Dundee, Angus, and Fife, Eastern Scotland, UK. PARTICIPANTS: A total of 1240 boys and 1214 girls aged between 4-10 y. MAIN OUTCOME MEASURE: Weight, height and body mass index (weight/height2). RESULTS: Overall overweight or obesity prevalence was 24.6%, while prevalence of obesity alone was 6.1%. Individuals from schools with a high level of low-income families were 65% more likely to be overweight as judged by BMI. However, these children weighed the same as more affluent children of the same age, but were 1.26 cm shorter. CONCLUSION: These data confirm the continued increase in childhood obesity in the UK and reveal a role for height-growth limitation in the absence of overall growth restriction, among children from low-income groups. This observation raises important questions regarding socioeconomic environmental factors in promoting the currently increasing levels of obesity.

Stress and eating: the effects of ego-threat and cognitive demand on food intake in restrained and emotional eaters.

Restrained and emotional eaters overeat in response to stress. To compare differential effects of cognitive demand and ego-threatening stressors on subsequent chocolate intake, 38 females completed a neutral (control), an ego threatening and an incongruent Stroop colour-naming task on three separate occasions. Participants were assigned to four groups based on median-split scores on the restrained and emotional eating scales of the Dutch Eating Behaviour Questionnaire-high restraint/high emotional, high restraint/low emotional, low restraint/high emotional and low restraint/low emotional. Higher response latencies were observed in the incongruent task, confirming its greater cognitive (attentional) demand. Overall intake was enhanced by 23% after ego-threat and 15% after the incongruent Stroop task relative to control. Restraint was associated with greater intake after both ego-threat and the incongruent task than in the control condition. In contrast, emotional eating was associated with greater intake after only the ego-threat, relative to control. A positive association between reaction time and subsequent intake in all conditions for high restraint/low emotional eaters provided support for the limited capacity hypothesis. Enhanced intake in emotional eaters is proposed to relate to escape from self-awareness. These findings demonstrate differential effects of threat and demand on stress-related eating in restrained and emotional eaters.

Stimulation of appetite by alcohol.

To investigate the effects of alcohol on appetite and food intake, 26 males attended the laboratory on three occasions. On each occasion, they were given a standard breakfast. Visual analog scale ratings of hunger, desire to eat and fullness (appetite ratings) were recorded from before breakfast until their return to the laboratory for lunch. Thirty minutes before lunch, subjects either rested (baseline), were given 330 ml of a no-alcohol lager (264 kJ: no-alcohol condition) or 330 ml of the same lager spiked with 3 units of alcohol (24 g ethyl alcohol; total energy=969 kJ: alcohol condition). Ratings of appetite were taken before and after the preload or baseline rest period and again before and hourly after lunch. The test meal at lunch consisted of a buffet-style array of foods and chilled water. Ad libitum intake at lunch (excluding energy from alcohol) was significantly higher following alcohol (7301+/-442 kJ) compared to both baseline (6365+/-334 kJ) and the no-alcohol conditions (6479+/-289 kJ). Appetite ratings failed to demonstrate any differences between alcohol and the no-alcohol condition. Total energy intake (including energy from alcohol) was enhanced in the alcohol condition by 30%, suggesting that energy from alcohol is not compensated in the short-term and may even have a stimulatory effect on food intake.