Neutral carbon in post-asymptotic giant branch stars and planetary nebulae

The 492 GHz ( 3P 1 → 3P 0) fine-structure line of neutral atomic carbon (C I) has been observed in the planetary nebulae (PNe) NGC 6302, IRAS 21282+5050, and NGC 7027, and in the protoplanetary nebula (PPN) AFGL 2688. The estimated C I/CO abundance ratio is higher for a more evolved object, consistent with a trend that the C I/CO ratio increases with the evolution of a post-asymptotic giant branch system from a PPN to a PN. Nondetections are also reported on 11 PPNe and extreme carbon stars. The upper limits placed on these objects suggest that they have C I abundances lower than the level found in the PPN AFGL 2688, again consistent with an increasing C I/CO ratio with evolution.published_or_final_versio

Molecular line emissions from the photodissociation region of NGC 7027

We have observed or searched for 11 molecular species in 17 transitions in the 200 and 300 GHz bands in the young planetary nebula NGC 7027. The results include a first detection of C 2H in this source. The observed spectra of HCO +, H 13CO +, HCN, CN, C 2H, and CO + show line widths wider than that of bulk CO emission but coincident with the full width at detection limit of weak wings in CO spectra. The HCO +, HCN, and CN emitting regions have a size of about 13″, significantly smaller than that of the CO emitting region. Thus, the emission of all the observed molecules other than CO and 13CO must originate from a very small volume compared with the entire CO envelope. Excitation analyses of six molecules with electron and neutral collisions at a gas temperature of 800 K yield similar density estimates ranging from 1.3 to 5 × 10 5 cm -3. Estimated column densities for HCO +, HCN, CN, CO +, and C 2H are in good agreement with predictions by a chemical model for the photodissociation region of NGC 7027. These analyses suggest that photochemistry is active in NGC 7027 and the observed molecular emissions (except CO) originate from the H 2 photodissociation zone of the object. © 2001. The American Astronomical Society. All rights reserved.published_or_final_versio

What is the value of built heritage? Assessing spillover effects of conserving historic sites in Singapore

10.1016/j.landusepol.2019.104393Land Use Policy9110439

Cost-effectiveness of a physical exercise programme for residents of care homes: a pilot study

BACKGROUND: Oomph! Wellness organises interactive exercise and activity classes (Oomph! classes) for older people in care homes. We investigated the cost-effectiveness of Oomph! classes. METHODS: Health-related quality of life was measured using the EQ-5D-5 L questionnaire at three time points; 3 months and 1 week prior to the start of the classes and after 3 months of Oomph! classes. Costs included the costs of organising the classes, training instructors and health service use (General Practitioner (GP) and hospital outpatient visits). To determine the cost-effectiveness of Oomph! classes, total costs and quality-adjusted life-years (QALYs) during the 3 months after initiation of the classes were compared to the total costs and QALYs of the 3 months prior to the classes and extrapolated to a 1-year time horizon. Uncertainty was taken into account using one-way and probabilistic sensitivity analysis. RESULTS: Sixteen residents completed all three EQ-5D-5 L questionnaires. There was a decrease in mean health related quality of life per participant in the 3 months before Oomph! classes (0.56 to 0.52, p = 0.26) and an increase in the 3 months after the start of Oomph! classes (0.52 to 0.60, p = 0.06), but the changes were not statistically significant. There were more GP visits after the start of Oomph! classes and fewer hospital outpatient visits, leading to a slight decrease in NHS costs (mean £132 vs £141 per participant), but the differences were not statistically significant (p = 0.79). In the base case scenario, total costs for Oomph! classes were £113 higher per participant than without Oomph! classes (£677 vs £564) and total QALYs were 0.074 higher (0.594 vs 0.520). The incremental costs per QALY gained were therefore £1531. The 95 % confidence intervals around the cost/QALY gained varied from dominant to dominated, meaning there was large uncertainty around the cost-effectiveness results. Given a willingness to pay threshold of £20,000 per QALY gained, Oomph! classes had a 62 %-86 % probability of being cost-effective depending on the scenario used. CONCLUSIONS: Preliminary evidence suggests that Oomph! classes may be cost-effective, but further evidence is needed about its impact on health-related quality of life and health service use

A realistic model of evaporation for a liquid droplet

An intuitive delineation along with dimensional considerations and experimental evidences are presented to show that in a general case, the evaporation of a liquid droplet undergoes three regimes through the process. Initially, the heat transfer inside the evaporating droplets is conduction controlled; then, in the second stage, convective heat transfer may take over; finally, the convections subside, and the process returns to conduction controlled mode

Optically powered communication system with distributed amplifiers

An optically powered communication system with distributed amplification is demonstrated using either distributed parametric amplification (DPA) or distributed Raman amplification (DRA) within the dispersion-shifted fiber (DSF) and single-mode fiber (SMF). At the fiber output the residual pump after the distributed amplification is recycled to power the receiver component. Our scheme is also a potential candidate for the last mile transmission. Based on our scheme, 4 channels of 10 Gb/s WDM signals are used to obtain practical performance evaluation. In the presence of 10-dB gain for signals, the power penalties of-dB at the BER of are achieved for DPA in DSF, and as the comparing counterpart of DPA, counter-pumping DRA induce approximately the same level of power penalty in DSF and -dB in SMF. Co-pumping DRA are also tested in both kind of fibers. Finally, the energy-efficiency issue for different pumping schemes is analyzed. © 2006 IEEE.published_or_final_versio