The 8th Habit from Effectiveness to Greatness

The 8th Habit shows how to solve such common dilemmas as : - People want peace of mind and good relationships, but also want to keep their listyle and habits. - Relationships are built on trust, but most people think more in terms of “me”- my wants, my needs, my rights. - Management wants more for less; employees want more of “what’s in it for me” for less time and effort. - Businesses are run by the economic rules of the marketplace; organizations are run by the cultural rules of the workplace. - Society operates by its dominant social values, mut must live the the consequences of the inviolable operation of natural laws and principles Covey’s new book will transform the way we think about ourselves and our purpose in life, about our organizations, and about humankind. Just as The 7 Habits of Highly Effective People helped us focus on effectiveness, The 8th Habit shows us the way to greatness

Evidence for Grain Growth in Molecular Clouds: A Bayesian Examination of the Extinction Law in Perseus

We investigate the shape of the extinction law in two $1^{\circ}$ square fields of the Perseus molecular cloud complex. We combine deep red-optical (r, i and z band) observations obtained using Megacam on the MMT with UKIRT (United Kingdom Infrared Telescope) Infrared Deep Sky Survey near-infrared (J, H and K band) data to measure the colours of background stars. We develop a new hierarchical Bayesian statistical model, including measurement error, intrinsic colour variation, spectral type and dust reddening, to simultaneously infer parameters for individual stars and characteristics of the population. We implement an efficient Markov chain Monte Carlo algorithm utilizing generalized Gibbs sampling to compute coherent probabilistic inferences. We find a strong correlation between the extinction $(A_V)$ and the slope of the extinction law (parametrized by $R_V)$. Because the majority of the extinction towards our stars comes from the Perseus molecular cloud, we interpret this correlation as evidence of grain growth at moderate optical depths. The extinction law changes from the ‘diffuse’ value of $R_V \sim 3$ to the 'dense cloud' value of $R_V \sim 5$ as the column density rises from $A_V = 2$ to 10 mag. This relationship is similar for the two regions in our study, despite their different physical conditions, suggesting that dust grain growth is a fairly universal process.Astronom

Young stars in the time domain

Variability is a defining characteristic of young stellar systems, and optical variability has been heavily studied to select and characterize the photospheric properties of young stars. In recent years, multi-epoch observations sampling a wider range of wavelengths and time-scales have revealed a wealth of time-variable phenomena at work during the star formation process. This splinter session was convened to summarize recent progress in providing improved coverage and understanding of time-variable processes in young stars and circumstellar disks. We begin by summarizing results from several multi-epoch Spitzer campaigns, which have demonstrated that many young stellar objects evidence significant mid-IR variability. While some of these variations can be attributed to processes in the stellar photosphere, others appear to trace short time-scale changes in the circumstellar disk which can be successfully modeled with axisymmetric or non-axisymmetric structures. We also review recent studies probing variability at shorter wavelengths that provide evidence for high frequency pulsations associated with accretion outbursts, correlated optical/X-ray variability in Classical T Tauri stars, and magnetic reversals in young solar analogs