Rod-like Polyelectrolytes in Presence of Monovalent Salt

We investigate the properties of rigid polyelectrolyte solutions in presence of monovalent salt. The free energy within the Debye-H\"uckel-Bjerrum (DHBj) theory [M. E. Fisher and Y. Levin, {\it Phys. Rev. Lett.} 71, 3826 (1993)] is constructed. It is found that at thermodynamic equilibrium the polyelectrolyte solution consists of clusters composed of one polyion and various counterions. The distribution of the cluster densities is determined by finding the minimum of the Helmholtz free energy. The osmotic pressure and the average charge of the cluster are found and their dependence on Manning parameter $\xi$ is elucidated. A good agreement with the experimental results is obtained.Comment: 11 pages, Revtex (using twocolumn style), 15 figures and postscript file. Submitted to Macromomelecule

Coparenting in Fragile Families

Nonmarital childbearing has increased dramatically in the U.S. since the early 1960s, rising from 6% of all births in 1960 to fully 40% in 2007 (Hamilton, Martin, & Ventura, 2009). Whereas similar trends have occurred in many developed nations, the U.S. stands out in the extent to which such births are associated with socioeconomic disadvantage and relationship instability. This has given rise to a new term ‘fragile families,’ which we define as unmarried couples who have a child together. The increase in fragile families reflects changes not only in the initial context of births but also in the fundamental nature and patterns of childrearing.Fragile families, childbearing, nonmarital childbearing

Fathers in Fragile Families

Nonmarital childbearing has increased dramatically in the U.S. since the early 1960s, rising from 6% of all births in 1960 to fully 40% in 2007 (Hamilton, Martin, & Ventura, 2009; Ventura & Bachrach, 2000). Whereas similar trends have occurred in many developed nations, the U.S. stands out in the extent to which such births are associated with socioeconomic disadvantage and relationship instability, giving rise to a new term ‘fragile families.’ The increase in fragile families reflects changes not only in the context of births but also in the fundamental nature and patterns of childrearing, particularly with respect to fathers’ roles and involvement with children.Fragile families, childbearing, nonmarital childbearing, fartherhood, fathers

Liquid Polymorphism and Density Anomaly in a Lattice Gas Model

We present a simple model for an associating liquid in which polymorphism and density anomaly are connected. Our model combines a two dimensional lattice gas with particles interacting through a soft core potential and orientational degrees of freedom represented through thermal \char`\"{}ice variables\char`\"{} . The competition between the directional attractive forces and the soft core potential leads to a phase diagram in which two liquid phases and a density anomaly are present. The coexistence line between the low density liquid and the high density liquid has a positive slope contradicting the surmise that the presence of a density anomaly implies that the high density liquid is more entropic than the low density liquid

Amphiphile Adsorption on Rigid Polyelectrolytes

A theory is presented which quantitatively accounts for the cooperative adsorption of cationic surfactants to anionic polyelectrolytes. For high salt concentration we find that the critical adsorption concentration (CAC) is a bilinear function of the polyion monomer and salt concentrations, with the coefficients dependent only on the type of surfactant used. The results presented in the paper might be useful for designing more efficient gene delivery systems

HAWAII LONGLINE VESSEL ECONOMICS

Public Economics,

The Basil and Josephine stories: Fitzgerald\u27s incompatible worlds

Typically, members of the middle-class of American society are fascinated by the extremely wealthy people of the upper-class. One can spend hours lost in daydreams about the lifestyles of the rich -- the intriguing and even famous people they encounter, the costly, luxurious garments they wear, or the delicacies they relish. To imagine such a life seems to lighten the drudgery of one\u27s own, possibly acting as a stimulus and driving one towards seemingly unattainable goals. The lives of the extremely wealthy are virtually impossible for most middle-class people to imagine, and likewise life in middle America may be difficult for the wealthy to comprehend. Few authors have been more interested in this relationship between the middle-class and the upper-class of America than F. Scott Fitzgerald was. In virtually all of his works, whether in his novels, short stories, poetry, essays or letters, this author\u27s fascination with the relationship between these two classes is ever-present