The Incidence of Debris Disks at 24 {\mu}m and 670 Myr

We use Spitzer Space Telescope 24 {\mu}m data to search for debris disks among 122 AFGKM stars from the \sim 670 Myr clusters Hyades, Coma Ber, and Praesepe, utilizing a number of advances in data reduction and determining the intrinsic colors of main sequence stars. For our sample, the 1{\sigma} dispersion about the main sequence V-K, K-[24] locus is approximately 3.1%. We identify seven debris disks at 10% or more (\geq 3{\sigma} confidence level) above the expected K-[24] for purely photospheric emission. The incidence of excesses of 10% or greater in our sample at this age is 5.7 +3.1/-1.7%. Combining with results from the literature, the rate is 7.8 +4.2/-2.1% for early- type (B9 - F4) stars and 2.7 +3.3/-1.7% for solar-like (F5 - K9) stars. Our primary sample has strict criteria for inclusion to allow comparison with other work; when we relax these criteria, three additional debris disks are detected. They are all around stars of solar-like type and hence reinforce our conclusion that disks around such stars are still relatively common at 670 Myr and are similar to the rate around early-type stars. The apparently small difference in decay rates between early-type and solar-like stars is inconsistent with the first order theoretical predictions that the later type stellar disks would decay an order of magnitude more quickly than the earlier type ones.Comment: 26 pages, 3 figures, accepted for publication in Ap

Bandwidth enhancement : correcting magnitude and phase distortion in wideband piezoelectric transducer systems

Acoustic ultrasonic measurements are widespread and commonly use transducers exhibiting resonant behaviour due to the piezoelectric nature of their active elements, being designed to give maximum sensitivity in the bandwidth of interest. We present a characterisation of such transducers that provides both magnitude and phase information describing the way in which the receiver responds to a surface displacement over its frequency range. Consequently, these devices work efficiently and linearly over only a very narrow band of their overall frequency range. In turn, this causes phase and magnitude distortion of linear signals. To correct for this distortion, we introduce a software technique, which considers only the input and the final output signals of the whole systemwhich is therefore generally applicable to any acoustic system. By correcting for the distortion of the magnitude and phase responses, we have ensured the signal seen at the receiver replicates the desired signal. We demonstrate a bandwidth extension on the received signal from 60-130 kHz at -6dB to 40-200 kHz at -1dB in a test system. The linear chirp signal we used to demonstrate this method showed the received signal to be almost identical to the desired linear chirp. Such systemcharacterisation will improve ultrasonic techniques when investigating material properties by maximising the accuracy of magnitude and phase estimations

Intraday REIT Liquidity

Real Estate Investment Trusts (REITs) may be classified as a real estate investment or more generally as an equity investment. While REITs are more liquid than direct real estate investments, the liquidity relationship between REITs and common stocks is less clear-cut. This study measures and analyzes the liquidity differences between REITs and other common stocks. The intraday variations documented in this study have implications for: 1) the appropriate timing of trades to minimize transaction costs and, 2) the substitutability of investments if illiquidity is priced. Our results reveal intraday patterns indicating lower liquidity for REITs than for common stocks when the liquidity measure is friction-based. In contrast, activity measures exhibit higher liquidity levels for REITs than for common stocks but this difference is only statistically significant at the beginning of the trading day. Finally, from an economic perspective we find that the ability to trade without influencing prices is 15-25% greater for non-REITS compared to REITs, and the price of immediacy is 7% higher for REITs.

Longer Lives Better Health: Helping Seniors Preserve Their Physical, Mental and Social Well-Being

This ROOTS is intended to celebrate the work the Foundation has done with many good partners to re-envision aging. By addressing the physical, social, technological, and environmental factors that minimize disability and foster prevention, we aim to change the trajectories of decline and dependence. But our aspirations go further. We believe that the years post-65 can be truly golden. Worries and challenges of youth and middle age are in the past. There can and should be much joy in the present. But our systems of care must change to better meet the needs of those who want independent living and community engagement. My hope is that this ROOTS will inspire others to join us in enhancing the well-being of older adults. And I encourage other foundations -- if not already engaged -- to contemplate the satisfactions of an aging agenda. If we do it right, while advances in medicine and technology are adding years to life, we can also add life to years

Policy Brief No. 1 - Cognitive Function, Aging and Paid Work

In the context of an aging population and aging workforce, we consider the relationship between cognitive function and paid work. Cognitive function is maintained for most adults as they age, and there is evidence of a positive relationship between stimulating and engaging work environments and both levels of cognitive function and their maintenance over time. At the same time, irregular and long work hours are associated with poorer cognitive outcomes. However, the relationship between paid work and cognitive function is complex; education and training as well as health status are also related to cognitive function and work. We discuss implications for policy makers and areas where further research is required

New technique joins the fight against footrot

The diagnosis of footrot in sheep and goats is not an easy task. Two main techniques are used for diagnosis - inspection of diseased feet on a farm and laboratory testing of bacteria isolated from foot scrapings. The interpretation of the results obtained by these methods requires a good understanding of the various forms of footrot. A new laboratory technique has halved the time taken to detect those strains of the bacterium, Bacteroides (Dichelobacter) nodosus, that cause each form of the disease

Mental Health Consequences of Romantic Betrayal: An Investigation of Depression and Anxiety

A report submitted by Laurie L. Couch and David R Olson to the Research and Creative Productions Committee in 2001 on the role of one\u27s personality characteristics in the experience of depressive and anxious symptomology after romantic betrayal