What Can the Price Gap between Branded and Private Label Products Tell Us about Markups?

In this paper we investigate the size of markups for nationally branded products sold in the U.S. retail grocery industry. Using scanner data from a large Midwestern supermarket chain, we compute several measures of upper and lower bounds on markup ratios for over 230 nationally branded products in 19 categories. Our method is based on the insight that retail and wholesale prices of private label products provide information on marginal costs that are also applicable to the appropriately matched nationally branded products. Under reasonable assumptions - the accuracy of which we consider in some detail - the wholesale price of a private label product is an upper bound for the marginal manufacturing cost of its nationally branded equivalent, while the retailer's margin on the national brand is an upper bound on the retailer's marginal handling cost for both the brand and private label versions. We find that lower bounds on the 'full' markup ratio range from 3.44 for toothbrushes and 2.23 for soft drinks to about 1.15-1.20 for canned tuna and frozen entrees, with the majority of categories falling in the range 1.40-2.10. Lower bounds on manufacturers' markups are even higher. Thus the data indicate that markups on nationally branded products sold in U.S. supermarkets are large.

On the genesis of BBP formulas

We present a general procedure to generate infinitely many BBP and BBP-like formulas for the simplest transcendental numbers. This provides some insight and a better understanding into their nature. In particular, we can derive the main known BBP formulas for π. We can understand why many of these formulas are rearrangements of each other. We also understand better where some null BBP formulas representing 0 come from. We also explain what is the observed relation between some BBP formulas for log 2 and π, that are obtained by taking real and imaginary parts of a general complex BBP formula. Our methods are elementary, but motivated by transal-gebraic considerations, and offer a new way to obtain and to search many new BBP formulas and, conjecturally, to better understand transalgebraic relations between transcendental constants

Randomly Crosslinked Macromolecular Systems: Vulcanisation Transition to and Properties of the Amorphous Solid State

As Charles Goodyear discovered in 1839, when he first vulcanised rubber, a macromolecular liquid is transformed into a solid when a sufficient density of permanent crosslinks is introduced at random. At this continuous equi- librium phase transition, the liquid state, in which all macromolecules are delocalised, is transformed into a solid state, in which a nonzero fraction of macromolecules have spontaneously become localised. This solid state is a most unusual one: localisation occurs about mean positions that are distributed homogeneously and randomly, and to an extent that varies randomly from monomer to monomer. Thus, the solid state emerging at the vulcanisation transition is an equilibrium amorphous solid state: it is properly viewed as a solid state that bears the same relationship to the liquid and crystalline states as the spin glass state of certain magnetic systems bears to the paramagnetic and ferromagnetic states, in the sense that, like the spin glass state, it is diagnosed by a subtle order parameter. In this review we give a detailed exposition of a theoretical approach to the physical properties of systems of randomly, permanently crosslinked macromolecules. Our primary focus is on the equilibrium properties of such systems, especially in the regime of Goodyear's vulcanisation transition.Comment: Review Article, REVTEX, 58 pages, 3 PostScript figure

The Mechanical Properties of PCNA: Implications for the Loading and Function of a DNA Sliding Clamp

Sliding clamps are toroidal proteins that encircle DNA and act as mobile platforms for DNA replication and repair machinery. To be loaded onto DNA, the eukaryotic sliding clamp Proliferating Cell Nuclear Antigen (PCNA) must be splayed open at one of the subunit-subunit interfaces by the ATP-dependent clamp loader, Replication Factor C, whose clamp-interacting sites form a right-handed spiral. Earlier molecular dynamics (MD) studies suggested that when PCNA opens, it preferentially adopts a right-handed spiral to match the spiral of the clamp loader. Here, analysis of considerably longer MD simulations shows that although the opened form of PCNA can achieve conformations matching the helical pitch of Replication Factor C, it is not biased toward a right-handed spiral structure. A coarse-grained elastic model was also built; its strong correspondence to the all-atom MD simulations of PCNA suggests that the behavior of the open clamp is primarily due to elastic deformation governed by the topology of the clamp domains. The elastic model was further used to construct the energy landscape of the opened PCNA clamp, including conformations that would allow binding to the clamp loader and loading onto double-stranded DNA. A picture of PCNA emerges of a rather flexible protein that, once opened, is mechanically compliant in the clamp opening process