Stem respiration rates are often quantified by measuring the CO(2) efflux from stems into chambers. It has been suggested that these measurements underestimate respiration because some of the respired CO(2) can be either retained or transported upwards in the transpiration stream. If the stem CO(2) efflux does not represent all respired CO(2), then the interpretation of its isotopic signal may be compromised as well. The C-isotope composition of the respired CO(2) and the measured efflux could differ due to (i) the release of CO(2) produced elsewhere into the stem and transported upwards in xylem water (soil CO(2) or root respired CO(2)); (ii) the retention or release of CO(2) storage pools within the tree stem and (iii) the removal of CO(2) by the transpiration stream. We investigated the effects of these processes in large conifer trees using two manipulative experiments: a labelling experiment and a crown removal experiment. The labelling experiment used an extreme enrichment of dissolved CO(2) in soil water to assess the C uptake by the roots. In this experiment, we found no contamination of the stem CO(2) pool despite clear evidence that the water itself had been taken up. The crown removal experiment tested for vertical CO(2) flux in xylem water by eliminating transpiration. Here, we found no change in the delta(13)C of stem CO(2) efflux (delta(EA); P > 0.05). We concluded that for these large conifers, sap-flow influenced neither delta(13)C of stem efflux nor that of the stem CO(2) pool. By parameterizing Henry's Law for conditions inside the stem, we estimated the transport flux to represent 1-3% of the stem CO(2) efflux to the atmosphere. Finally, assuming a 2 per thousand difference between delta(13)C of root and stem respiration, we estimated that potential contamination of delta(EA) by root respired CO(2) would be < 0.1 per thousand. Thus, neither the release of soil or root CO(2), nor storage in the stem, nor vertical transport of CO(2) in the xylem sap had any detectable influence on delta(13)C of the CO(2) measured in stem efflux.

We report on quaternary AlInGaN/InGaN multiple quantum well (MQW) light emitting diode structures grown on sapphire substrates. The structures demonstrate high quality of the p–n junctions with quaternary MQW. At low forward bias (below 2 V), the temperature dependent of current–voltage characteristics are exponential with the ideality factor of 2.28, which is in a good agreement with the model of the injected carrier recombination in the space charge region. This ideality factor value is approximately three times lower than for conventional GaN/InGaN light emitting diodes (LEDs). The obtained data indicate the recombination in p–n junction space charge region to be responsible for a current transport in LED structures with quaternary quantum wells. This is in contrast to InGaN based LEDs, where carrier tunneling dominates either because of high doping of the active layer or due to the high density of localized states.

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Background:This study was done to assess the determinants of morbidity pattern, quality of life (QoL) and awareness of elderly about various government schemes and social security legislations.Materials and Methods:Data was collected by house to house survey among participants aged 60 years and above using a structured interview schedule. The QoL was assessed using Kannada version of WHOQOL-BREF instrument following language validation.Results:Mean age of 206 participants was 69.6±6.7 years. Half of them were males and majority were graduates 54 (26.2%). Morbidity was present among 194 (94.2%) participants (95% CI 89.5–98.9%), most common being hypertension 96 (46.6%). Morbid conditions were seen more among less educated (P = 0.007). Only 68 (33%) were under medical insurance coverage, 17 (8.3%) were under old age government pension and 74 (35.9%) were under retirement pension scheme. Social relationships, psychological health and environmental domain scores were associated with socio-economic status. Social relationship domain score was significantly better among well educated participants and those without morbidities. Level of ambulation was significantly associated with QoL scores in all domains (P < 0.001). Majority of the participants 132 (64.1%) had moderate level of awareness about government facilities for senior citizens. Awareness level was significantly better among males (P < 0.001), well educated (P < 0.001), better socio-economic status respondents (P < 0.001) and those currently working (P = 0.026).Conclusion:Health status of elderly needs improvement which would also improve their QoL. Awareness about various government schemes needs to be enhanced to improve its utilization. The results of this study are expected to help policy makers in planning comprehensive services for elderly residing in this area.