An alternative to Kitcher's theory of conceptual progress and his account of the change of the gene concept

The present paper discusses Kitcher’s framework for studying conceptual change and progress. Kitcher’s core notion of reference potential is hard to apply to concrete cases. In addition, an account of conceptual change as change in reference potential misses some important aspects of conceptual change and conceptual progress. I propose an alternative framework that focuses on the inferences and explanations supported by scientific concepts. The application of my approach to the history of the gene concept offers a better account of the conceptual progress that occurred in the transition from the Mendelian to the molecular gene than Kitcher’s theory

Proton charge radius from electron scattering

The rms-radius $R$ of the proton charge distribution is a fundamental quantity needed for precision physics. This radius, traditionally determined from elastic electron-proton scattering via the slope of the Sachs form factor $G_e(q^2)$ extrapolated to momentum transfer $q^2$=0, shows a large scatter. We discuss the approaches used to analyze the e-p data, partly redo these analyses in order to identify the sources of the discrepancies, and explore alternative parameterizations. The problem lies in the model dependence of the parameterized $G(q)$ needed for the extrapolation. This shape of $G(q<q_{min})$ is closely related to the shape of the charge density $\rho (r)$ at large radii $r$, a quantity which is ignored in most analyses. When using our {\em physics} knowledge about this large-$r$ density together with the information contained in the high-$q$ data, the model dependence of the extrapolation is reduced and different parameterizations of the pre-2010 data yield a consistent value for $R = 0.887 \pm 0.012fm$. This value disagrees with the more precise value $0.8409 \pm 0.0004 fm$ determined from the Lamb shift in muonic hydrogen.Comment: To be published in special issue of Atoms "High precision mesurements of fundamental constants

Sulfur and baking-quality of breadmaking wheat

It is well known in biological science that all factors applied to living organisms (light, water, warmth, fertilizers etc.) show an optimum, when their input is increased. Healthy organisms and sus-tainable systems are, on the long run, only achieved when care is taken not to destroy this equilibrium of factors producing an optimum. With regard to the baking quality of wheat breeders and cereal scientists obviously failed to achieve this aim by breeding their cultivars on the background of ample S depositions in the ecosystems. They (involuntarily) selected plants showing definite characteristics of S deficiency (higher proportions of HMW-glutenin, stronger gluten and dough) even under conditions of ample S supply. I suppose they also selected plants with a high warmth susceptibility as this also delivers firm protein structure. When this environ-mental pollution was stopped and S supplies returned to natural conditions, even with a non S craving plant like wheat, problems arose with the gluten structure as doughs turned out so strong that the baking volume decreased. So one may ask, particularly with regard to S, if the plant constitutions of our modern wheat cultivars are still harmonious and in balance. And as a consequence ot that also the nutritional quality of these cultivars is rather questionable

The theoretical derivation of credit market segmentation as the result of a free market process

Information asymmetries make it difficult for banks to assess accurately whether specific entrepreneurs are able and/or willing to repay their loans. This leads to implicit interest rate ceilings, i.e. banks "refuse" to increase their interest rates beyond this ceiling as this would lower their net returns. Although the maximum interest rate increases as the size of enterprises decreases, such ceilings nonetheless constrain the banks’ ability to set interest rates at a level that would enable them to cover costs. If transaction costs are high, the total costs associated with granting small and medium-sized loans will exceed the maximum average return which the banks can earn by issuing such loans. For this reason, banks do not lend to small and medium-sized enterprises, and, as a consequence, these businesses have no access to formal sector loans. Because micro and small enterprises have a very high RoI, it is worthwhile for them to rely on expensive informal loans to finance their operations, at least until they reach a certain size. Once they have reached this size, however, it does not make economic sense for them to continue taking out informal credits, and thus they face a growth constraint imposed by the credit market. Medium-sized enterprises earn a lower RoI than small ones, which is why borrowing in the informal credit market is not a worthwhile option for them. Moreover, they do not have access to credit from formal financial institutions, and are thus excluded from obtaining any kind of financing in either of the two credit markets. As the result of free, unregulated market forces we get a stable equilibrium in which the credit market is segmented into an informal (small loan) segment, a formal (large loan) segment and, in between, a "non-market" (medium loan) segment