Critical holes in undercooled wetting layers

The profile of a critical hole in an undercooled wetting layer is determined by the saddle-point equation of a standard interface Hamiltonian supported by convenient boundary conditions. It is shown that this saddle-point equation can be mapped onto an autonomous dynamical system in a three-dimensional phase space. The corresponding flux has a polynomial form and in general displays four fixed points, each with different stability properties. On the basis of this picture we derive the thermodynamic behaviour of critical holes in three different nucleation regimes of the phase diagram.Comment: 18 pages, LaTeX, 6 figures Postscript, submitted to J. Phys.

Mechanical tension and spontaneous muscle twitching precede the formation of cross-striated muscle in vivo

Muscle forces are produced by repeated stereotypical actomyosin units called sarcomeres. Sarcomeres are chained into linear myofibrils spanning the entire muscle fiber. In mammalian body muscles, myofibrils are aligned laterally, resulting in their typical cross-striated morphology. Despite this detailed textbook knowledge about the adult muscle structure, it is still unclear how cross-striated myofibrils are built in vivo. Here, we investigate the morphogenesis of Drosophila abdominal muscles and establish them as an in vivo model for cross-striated muscle development. By performing live imaging, we find that long immature myofibrils lacking a periodic actomyosin pattern are built simultaneously in the entire muscle fiber and then align laterally to give mature cross-striated myofibrils. Interestingly, laser micro-lesion experiments demonstrate that mechanical tension precedes the formation of the immature myofibrils. Moreover, these immature myofibrils do generate spontaneous Ca2+-dependent contractions in vivo, which, when chemically blocked, result in cross-striation defects. Taken together, these results suggest a myofibrillogenesis model in which mechanical tension and spontaneous muscle twitching synchronize the simultaneous self-organization of different sarcomeric protein complexes to build highly regular cross-striated myofibrils spanning the length of large muscle fibers

Ein Status Quo: Haben Milchkühe Zahnprobleme?

Dental abnormalities in cows have seldomly been examined in research and veterinary check-up. This study estimated the prevalence of dental problems in cows. The skulls of 151 adult (> 4 years) dairy cows (Brown Swiss cattle n=81, Swiss Fleckvieh n=70) were categorized into three age groups (AK1: 4-6 / AK2: 7-9 / AK3: 10-16 years old) and examined for the existence of 11 dental cheek teeth abnormalities, based on well-known dental pathologies in horses. The four most prevalent dental abnormalities found were presence of abnormal spaces between 2 adjacent cheek teeth (Diastema), parodontosis, wavemouth, and food packing between cheek teeth. In 85% of all recorded skulls, 1 or more abnormalities were recorded. There were no differences in the occurrence of dental abnormalities in the two breeds. Older animals of AK3 showed more abnormalities than younger animals, but also in the lower age categories, in average 2 abnormalities per skull were recorded. 36% of all skulls showed the presence of Diastema, which has been described as one of the most painful oral abnormalities in horse. Dental abnormalities are prevalent in cows and probably a not recognized cause of health disorders

Evapotranspiration of native vegetation in the closed basin of the San Luis Valley, Colorado

June 1987.Bibliography: page 21.Grant nos. 14-08-001-G895 and 14-08-0001-G1006; project no. 06; financed in part by the U.S. Department of the Interior, Geological Survey and Bureau of Reclamation, through the Colorado Water Resources Research Institute in cooperation with the U.S.D.A. Agricultural Research Service

One-Bead Microrheology with Rotating Particles

We lay the theoretical basis for one-bead microrheology with rotating particles, i.e, a method where colloids are used to probe the mechanical properties of viscoelastic media. Based on a two-fluid model, we calculate the compliance and discuss it for two cases. We first assume that the elastic and fluid component exhibit both stick boundary conditions at the particle surface. Then, the compliance fulfills a generalized Stokes law with a complex shear modulus whose validity is only limited by inertial effects, in contrast to translational motion. Secondly, we find that the validity of the Stokes regime is reduced when the elastic network is not coupled to the particleComment: 7 pages, 5 figures, submitted to Europhys. Let

Grain Boundary Scars and Spherical Crystallography

We describe experimental investigations of the structure of two-dimensional spherical crystals. The crystals, formed by beads self-assembled on water droplets in oil, serve as model systems for exploring very general theories about the minimum energy configurations of particles with arbitrary repulsive interactions on curved surfaces. Above a critical system size we find that crystals develop distinctive high-angle grain boundaries, or scars, not found in planar crystals. The number of excess defects in a scar is shown to grow linearly with the dimensionless system size. The observed slope is expected to be universal, independent of the microscopic potential.Comment: 4 pages, 3 eps figs (high quality images available from Mark Bowick

Alpine Space Prospective Study. Sustainable territorial development in the Alpine Space: Towards long term transnational cooperation

This "Prospective Study" argues that a long term transnational cooperation will be able to pursue the sustainable territorial development in the Alpine Space only at the condition of a substantial improvement of the current experience. This regards an increased awareness of the complexity of issues and challenges currently at stake in the Alpine area but especially, in this light, the capacity of involving all relevant institutional and socioeconomic stakeholders in the building of shared transnational strategie

Outbreak of Marburg hemorrhagic fever among miners in Kamwenge and Ibanda Districts, Uganda, 2007

Marburg hemorrhagic fever was detected among 4 miners in Ibanda District, Uganda, from June through September, 2007. Infection was likely acquired through exposure to bats or bat secretions in a mine in Kamwenge District, Uganda, and possibly human-to-human transmission between some patients. We describe the epidemiologic investigation and the health education response

Alpine Space Prospective Study. Sustainable territorial development in the Alpine Space: Towards long term transnational cooperation

This "Prospective Study" argues that a long term transnational cooperation will be able to pursue the sustainable territorial development in the Alpine Space only at the condition of a substantial improvement of the current experience. This regards an increased awareness of the complexity of issues and challenges currently at stake in the Alpine area but especially, in this light, the capacity of involving all relevant institutional and socioeconomic stakeholders in the building of shared transnational strategies