Rider University

About: Rider University is a education organization based out in Lawrenceville, New Jersey, United States. It is known for research contribution in the topics: Dosimetry & Creativity. The organization has 881 authors who have published 1934 publications receiving 50752 citations.

A New Look at an Old Cluster: The Membership, Rotation, and Magnetic Activity of Low-mass Stars in the 1.3 Gyr Old Open Cluster NGC 752

Abstract: The nearby open cluster NGC 752 presents a rare opportunity to study stellar properties at ages >1 Gyr. However, constructing a membership catalog for it is challenging; most surveys have been limited to identifying its giants and dwarf members earlier than mid-K. We supplement past membership catalogs with candidates selected with updated photometric and proper-motion criteria, generating a list of 258 members, a >50% increase over previous catalogs. Using a Bayesian framework to fit MESA Isochrones & Stellar Tracks evolutionary models to literature photometry and the Tycho-Gaia Astrometric Solution data available for 59 cluster members, we infer the age of, and distance to, NGC 752: 1.34$\pm$0.06 Gyr and 438$_{-6}^{+8}$ pc. We also report the results of our optical monitoring of the cluster using the Palomar Transient Factory. We obtain rotation periods for 12 K and M cluster members, the first periods measured for such low-mass stars with a well-constrained age >1 Gyr. We compare these new periods to data from the younger clusters Praesepe and NGC 6811, and to a theoretical model for angular-momentum loss, to examine stellar spin down for low-mass stars over their first 1.3 Gyr. While on average NGC 752 stars are rotating more slowly than their younger counterparts, the difference is not significant. Finally, we use our spectroscopic observations to measure Halpha for cluster stars, finding that members earlier than $\approx$M2 are magnetically inactive, as expected at this age. Forthcoming Gaia data should solidify and extend the membership of NGC 752 to lower masses, thereby increasing its importance for studies of low-mass stars.

How Divergent Thinking Tests Mislead Us: Are the Torrance Tests Still Relevant in the 21st Century? The Division 10 Debate

Abstract: An adult observed a preschool child working assiduously on a drawing and asked, “What are you drawing?” Without looking up, the child responded, “I’m drawing the face of God.” The adult smiled and said, “But no one knows what God looks like.” The child answered, “They will in a couple minutes.” No one is really sure what creativity looks like either, but half a century ago Joy Guilford described one important piece of it—divergent production—and Guilford’s vision has shaped what many of us think creativity looks like, especially in the area of creativity assessment. The Torrance Tests are essentially divergent thinking tests based on Guilford’s model, and they are very widely used as creativity tests. Although the Torrance Tests have lost some of the edge they had quarter of a century ago, when Torrance and Presbury (1984) reported that the Torrance Tests had been used in three quarters of all recently published studies of creativity, they nonetheless remain an important force, although perhaps more in schools than in research. If they are valid measures of creativity, that’s wonderful. If they are not, it’s a huge problem. It would mean that we may think we know a lot of things—things we’ve learned from research by using a possibly invalid tool—that we don’t really know. Guilford grouped his divergent-production factors into four categories, and those four categories—fluency, flexibility, originality, and elaboration—were the basis of the Torrance Tests for many years. Torrance cautioned against the use of a composite score, recommending instead that the subscales be interpreted “in relation to one another” to get a picture of an individual’s skills:

Usf1, a suppressor of the circadian Clock mutant, reveals the nature of the DNA-binding of the CLOCK:BMAL1 complex in mice

Abstract: Circadian rhythms are biochemical, physiological and behavioral processes that follow a 24-hr cycle, responding primarily to the periods of light and dark, and they have been observed in bacteria, fungi, plants and animals. The circadian clock that drives these rhythms—which dictate our sleep patterns and other processes—involves a set of genes and proteins that participate in a collection of positive and negative feedback loops. Previous research has mainly focused on identifying core clock genes—that is, genes that make up the molecular clock—and studying the functions of these genes and the proteins they code for. However, it has become clear that other clock genes are also involved in circadian behavior, and it has been proposed that polymorphisms in these non-core clock genes could contribute to the variations in circadian behavior displayed by different mammals. One important feedback loop in mammals involves two key transcription factors, CLOCK and BMAL1, that combine to form a complex that initiates the transcription of the negative feedback genes, Period and Cryptochrome. Shimomura et al. discovered that Usf1, a gene that codes for a transcription factor that is typically involved in lipid and carbohydrate metabolism, as well as other cellular processes, is also important. In particular, this transcription factor is capable of partially rescuing an abnormal circadian rhythm caused by a mutation in the Clock gene in mice. Shimomura et al. showed that the proteins expressed by the mutant Clock gene can bind to the same regulatory sites in the genome as the normal CLOCK:BMAL1 complex, but that gene expression of these targets is reduced because transcriptional activation is lower and binding of the complex is not as strong. However, proteins expressed by the Usf1 gene are able to counter this by binding to the same sites in the genome and compensating for the mutant CLOCK protein. Further experiments are needed to explore how the interactions between the USF1 and CLOCK:BMAL1 transcriptional networks regulate circadian rhythms and, possibly, carbohydrate and lipid metabolism as well.