Identification and evaluation of linear damping models in beam vibrations

Sensitive method, identifying effective damping mechanisms, involves comparing experimentally determined ratio of first to second mode magnification factors related to common point on beam. Cluster size has little effect on frequencies of elements, magnification factor decreases with cluster size, and viscous and stress damping are dominant damping mechanisms

Research on processes for utilization of lunar resources quarterly report, 16 jul. - 15 oct. 1964

Lunar resource utilization - silicate reduction unit and carbon monoxide reduction reacto

Discovery of Blue Hook Stars in the Massive Globular Cluster M54

We present BV photometry centered on the globular cluster M54 (NGC 6715). The color-magnitude diagram clearly shows a blue horizontal branch extending anomalously beyond the zero age horizontal branch theoretical models. These kinds of horizontal branch stars (also called ``blue hook'' stars), which go beyond the lower limit of the envelope mass of canonical horizontal branch hot stars, have so far been known to exist in only a few globular clusters: NGC 2808, Omega Centauri (NGC 5139), NGC 6273, and NGC 6388. Those clusters, like M54, are among the most luminous in our Galaxy, indicating a possible correlation between the existence of these types of horizontal branch stars and the total mass of the cluster. A gap in the observed horizontal branch of M54 around T(eff)= 27000 K could be interpreted within the late helium flash theoretical scenario, a possible explanation for the origin of those stars.Comment: 10 pages, 2 figures, accepted for publication in the Astrophysical Journa

Parents' involvement in child care: do parental and work identities matter?

The current study draws on identity theory to explore mothers' and fathers' involvement in childcare. It examined the relationships between the salience and centrality of individuals’ parental and work-related identities and the extent to which they are involved in various forms of childcare. A sample of 148 couples with at least one child aged 6 years or younger completed extensive questionnaires. As hypothesized, the salience and centrality of parental identities were positively related to mothers' and fathers' involvement in childcare. Moreover, maternal identity salience was negatively related to fathers' hours of childcare and share of childcare tasks. Finally, work hours mediated the negative relationships between the centrality of work identities and time invested in childcare, and gender moderated this mediation effect. That is, the more central a mother's work identity, the more hours she worked for pay and the fewer hours she invested in childcare. These findings shed light on the role of parental identities in guiding behavioral choices, and attest to the importance of distinguishing between identity salience and centrality as two components of self-structure

Relativistic Lee Model on Riemannian Manifolds

We study the relativistic Lee model on static Riemannian manifolds. The model is constructed nonperturbatively through its resolvent, which is based on the so-called principal operator and the heat kernel techniques. It is shown that making the principal operator well-defined dictates how to renormalize the parameters of the model. The renormalization of the parameters are the same in the light front coordinates as in the instant form. Moreover, the renormalization of the model on Riemannian manifolds agrees with the flat case. The asymptotic behavior of the renormalized principal operator in the large number of bosons limit implies that the ground state energy is positive. In 2+1 dimensions, the model requires only a mass renormalization. We obtain rigorous bounds on the ground state energy for the n-particle sector of 2+1 dimensional model.Comment: 23 pages, added a new section, corrected typos and slightly different titl