Force networks and the dynamic approach to jamming in sheared granular media

Diverging correlation lengths on either side of the jamming transition are used to formulate a rheological model of granular shear flow, based on the propagation of stress through force chain networks. The model predicts three distinct flow regimes, characterized by the shear rate dependence of the stress tensor, that have been observed in both simulations and experiments. The boundaries separating the flow regimes are quantitatively determined and testable. In the limit of jammed granular solids, the model predicts the observed anomalous scaling of the shear modulus and a new relation for the shear strain at yield

Monetary policy and the federal funds futures market

How well did the federal funds futures market anticipate recent monetary policy actions? The authors examine the predictive content of fed funds futures rates, which provide the Federal Open Market Committee with a clear reading of market expectations for policy, in the context of 1994 policy moves and analyze the fed funds futures market outlook in early 1995.Monetary policy ; Federal funds market (United States)

WHO EATS WHAT, WHEN, AND FROM WHERE?

The popular impression that over half of our food does not come from a retail food (grocery) store is based on food expenditure data and is misleading. This research set out to learn where people obtain the food they report eating and to determine whether there are significant differences between people who buy most of their food from retail food stores and those who do not. Research on food consumption often focuses on household expenditures at retail food stores and various types of restaurants, but tracking the volume of various types of foods purchased from various retail places is not well established. The Continuing Survey of Food Intake of Individuals survey for 1994 showed that 72 percent of the volume of food consumed was from retail food stores. Age had the largest impact on where people shopped, and when and how many meals they ate. Income and household composition had relatively little impact. Cluster analysis grouped consumers based on where they obtained their food. The largest cluster, nearly half of the individuals, were labeled the Home Cookers. They obtained 93 percent of their food from stores and account for 59 percent of food sold from retail food stores. The High Service cluster is only 10 percent of the sample, but they consumed 50 percent of the food sold in restaurants and only 6 percent of food sold by grocers. Looking at the diets of people in the various clusters reveal that those in the Fast Food clusters ate less fat than the average of the sample while High Service (restaurant) users ate more fat. Home Cookers ate less than the average amount of meat, eggs, and vegetables.Food Consumption/Nutrition/Food Safety,

Coevolutionary immune system dynamics driving pathogen speciation

We introduce and analyze a within-host dynamical model of the coevolution between rapidly mutating pathogens and the adaptive immune response. Pathogen mutation and a homeostatic constraint on lymphocytes both play a role in allowing the development of chronic infection, rather than quick pathogen clearance. The dynamics of these chronic infections display emergent structure, including branching patterns corresponding to asexual pathogen speciation, which is fundamentally driven by the coevolutionary interaction. Over time, continued branching creates an increasingly fragile immune system, and leads to the eventual catastrophic loss of immune control.Comment: main article: 16 pages, 5 figures; supporting information: 3 page

Preparation of C2 symmetric transition metal complexes as potential chiral catalysts

Catalytic asymmetric synthesis is of great importance to the industrial production of biologically active substances such as pharmaceuticals, flavoring and sweetening agents, and insecticides. A special class of C2 symmetric transition chiral metal complexes has proven very useful in catalytic asymmetric synthesis