A Study of Cool White Dwarfs in the Sloan Digital Sky Survey Data Release 12

In this work we study white dwarfs where $30\,000\,\text{K} {>} \mathrm{T}_{\rm{eff}} {>} 5\,000\,\text{K}$ to compare the differences in the cooling of DAs and non-DAs and their formation channels. Our final sample is composed by nearly $13\,000$ DAs and more than $3\,000$ non-DAs that are simultaneously in the SDSS DR12 spectroscopic database and in the \textit{Gaia} survey DR2. We present the mass distribution for DAs, DBs and DCs, where it is found that the DCs are ${\sim}0.15\,\mathrm{M}_\odot$ more massive than DAs and DBs on average. Also we present the photometric effective temperature distribution for each spectral type and the distance distribution for DAs and non-DAs. In addition, we study the ratio of non-DAs to DAs as a function of effective temperature. We find that this ratio is around ${\sim}0.075$ for effective temperature above ${\sim}22\,000\,\text{K}$ and increases by a factor of five for effective temperature cooler than $15\,000\,\text{K}$. If we assume that the increase of non-DA stars between ${\sim}22\,000\,\text{K}$ to ${\sim}15\,000\,\text{K}$ is due to convective dilution, $14{\pm}3$ per cent of the DAs should turn into non-DAs to explain the observed ratio. Our determination of the mass distribution of DCs also agrees with the theory that convective dilution and mixing are more likely to occur in massive white dwarfs, which supports evolutionary models and observations suggesting that higher mass white dwarfs have thinner hydrogen layers.Comment: 9 pages, 10 figures, accepted by MNRA

Micro-bias and macro-performance

We use agent-based modeling to investigate the effect of conservatism and partisanship on the efficiency with which large populations solve the density classification task--a paradigmatic problem for information aggregation and consensus building. We find that conservative agents enhance the populations' ability to efficiently solve the density classification task despite large levels of noise in the system. In contrast, we find that the presence of even a small fraction of partisans holding the minority position will result in deadlock or a consensus on an incorrect answer. Our results provide a possible explanation for the emergence of conservatism and suggest that even low levels of partisanship can lead to significant social costs.Comment: 11 pages, 5 figure

Desert Palms

DESERT PALMS is a contemporary women’s novel set in an Arizona RV park. When Miamians Margie Campos and her husband, Carlos, unexpectantly inherit Desert Palms, a rundown retirement community, Margie reluctantly agrees to stay in Arizona to overhaul the park. With the discovery of a secret letter that threatens to unravel the family, an unscrupulous broker determined to buy the park on the cheap, and a husband bent on hitting it big, Margie digs in and starts to find purpose amidst a desert microcosm. Told from Margie’s perspective in a closely attached third person, DESERT PALMS is a realistic and humorous narrative that falls somewhere between the style of Liane Moriarty in, “The Husband’s Secret” and Anne Tyler in her novel, “Back When We Were Grownups.” DESERT PALMS offers an offbeat cast of central characters who help Margie gain a deeper understanding of herself and what makes life worth living

Cooling by sweeping: a new operation method to achieve ferroic refrigeration without fluids or thermally switchable components

So far, all ferroic-based refrigerator prototypes have relied either in fluids or thermally switchable components as main heat exchangers, which brings some issues in terms of their applicability, such as the use of pumps for moving the fluid and the availability of thermally switchable components. We show that such heat exchangers are not necessary if field dynamics are explored. By using the example of magnetocaloric refrigeration, we show numerically that the operation of a simple apparatus constituted only by a magnetocaloric material and a magnet sweeping at a given frequency results in refrigeration. With the optimization of the type of motion, resting times after the complete application and removal of the magnetic field and frequency, a temperature span of 0.87 K is reached, which represents  ∼ 20% of the maximum adiabatic temperature span of the material used in modeling, gadolinium.publishe