Force-induced unfolding of a homopolymer on fractal lattice: exact results vs. mean field predictions

We study the force-induced unfolding of a homopolymer on the three dimensional Sierpinski gasket. The polymer is subject to a contact energy between nearest neighbour sites not consecutive along the chain and to a stretching force. The hierarchical nature of the lattice we consider allows for an exact treatment which yields the phase diagram and the critical behaviour. We show that for this model mean field predictions are not correct, in particular in the exact phase diagram there is {\em not} a low temperature reentrance and we find that the force induced unfolding transition below the theta temperature is second order.Comment: 15 pages, 5 eps figure

A mineralized zone in Western Candor Chasma, Mars

Spectral evidence from Viking and Phobos orbiting spacecraft suggests the local development of crystalline ferric oxides in a small region within Mars' equatorial Valles Marineris canyon system. This is the same area noted for its anomalous coloration in Viking Orbiter image 583 A by McEwen. The unique hue of the region in Viking color data is due to a reduced green filter reflectance, relative to violet and red, in comparison to surrounding materials of similar albedo or average reflectance. For this reason, the region does not appear spectrally distinctive in later Survey Mission images which were acquired without the green filter. In high resolution, the spectral unit can be seen to correspond to two 20 km long depressions on the margins of Candor Mensa, a heavily eroded plateau-forming deposit on the canyon floor. Laminae are conspicuous in several places on the plateau, particularly where 15 to 20 cycles of alternating bright and dark laminae are exposed at approximately 200 meter vertical intervals. Laminae are also visible on the steep, vertically fluted cliffs to the south of this depression. Concentric laminae indicate a basis in the depression on the southeastern margin of Candor Mensa at the location of the less pronounced hue anomaly. A distinct lineation at the base of the scarp at the western end of the canyon transects mottled canyon floor deposits believed to be among the youngest in the Valles marineris. Water is implicated in the formation of the iron oxides, since the steep surfaces of layered sediments elsewhere on Candor Mensa show no evidence of unusual coloration despite the fact that these materials were deposited concurrently with the strata exposed in the depressions. This suggests that the mineralization is secondary in nature and developed locally in association with the depressions, which could have ponded surface runoff or groundwater seepage

Transferable Pair Potentials for CdS and ZnS Crystals

A set of interatomic pair potentials is developed for CdS and ZnS crystals. We show that a simple energy function, which has been used to describe the properties of CdSe [J. Chem. Phys. 116, 258 (2002)], can be parametrized to accurately describe the lattice and elastic constants, and phonon dispersion relations of bulk CdS and ZnS in the wurtzite and rocksalt crystal structures. The predicted coexistence pressure of the wurtzite and rocksalt structures, as well as the equation of state are in good agreement with experimental observations. These new pair potentials enable the study of a wide range of processes in bulk and nanocrystalline II-VI semiconductor materials

Reducing the Spread of Infectious Disease Through Hand Washing

According to the Centers for Disease Control (2002), hand washing is the simplest, most effective measure for preventing the spread of bacteria, pathogens, and viruses. Recent studies by the American Society for Microbiology (2005) indicate that Americans do not wash their hands after going to the bathroom and before handling or eating food. The study reported here sought to determine the presence of publications encouraging the public to wash hands in two North Carolina counties. Public restrooms located in rest areas, convenience stores, restaurants, and childcare facilities were examined. Findings indicate that literature encouraging hand washing is not present

Investigating Rare Events by Transition Interface Sampling

We briefly review simulation schemes for the investigation of rare transitions and we resume the recently introduced Transition Interface Sampling, a method in which the computation of rate constants is recast into the computation of fluxes through interfaces dividing the reactant and product state.Comment: 12 pages, 1 figure, contributed paper to the proceedings of NEXT 2003, Second Sardinian International Conference on News and Expectations in Thermostatistics, 21-28 Sep 2003, Cagliari (Italy

The design and implementation of a continuously updated class evaluation guide

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (p. 79).by Miguel G. Hall.M.Eng

Peptide-directed assembly of functional supramolecular polymers for biomedical applications: electroactive molecular tongue-twisters (oligoalanine-oligoaniline-oligoalanine) for electrochemically enhanced drug delivery

We report the preparation and characterization of films of electroactive supramolecular polymers based on non-electroactive oligoalanines and electroactive oligoanilines. Fibroblasts adhered to and proliferated on the films, and the delivery of the clinically relevant anti-inflammatory drug dexamethasone phosphate could be enhanced upon the application of an electrical stimulus

The case for new rural centralities in agricultural enclaves: three scenarios for Muggiano

Agricultural enclaves represent for cities both a challenge, they have to deal with connectivity and development issues, and an opportunity, they can be considered as resources for achieving major policy objectives such as better environmental protection or increased local food production. Among European metropolises, Milan’s case is quite original since it presents unique institutional arrangements and chiefly its agricultural park (Parco Agricolo Sud Milano – PASM). The territory of Muggiano is part of the PASM, at the fringe of the municipal territory, cut out from both the rest of the city and the rest of the park, it is undergoing a slow decline both in its agricultural and urban functions. Yet, field exploration revealed a more complex territory than expected, carrying a strong latent potential and presenting different challenges than expected. In a prospective effort, we elaborated 3 scenarios for the development of Muggiano: from a fully agricultural production one to another extreme one, focusing on residential uses. Our exploration led us to concluding that the “rural centrality” scenario, investing fully on agriculture but not only for its productive function, and spatially balancing the development along a “backbone”, was the best option Muggiano could go for

Galileo dust data from the jovian system: 2000 to 2003

The Galileo spacecraft was orbiting Jupiter between Dec 1995 and Sep 2003. The Galileo dust detector monitored the jovian dust environment between about 2 and 370 R_J (jovian radius R_J = 71492 km). We present data from the Galileo dust instrument for the period January 2000 to September 2003. We report on the data of 5389 particles measured between 2000 and the end of the mission in 2003. The majority of the 21250 particles for which the full set of measured impact parameters (impact time, impact direction, charge rise times, charge amplitudes, etc.) was transmitted to Earth were tiny grains (about 10 nm in radius), most of them originating from Jupiter's innermost Galilean moon Io. Their impact rates frequently exceeded 10 min^-1. Surprisingly large impact rates up to 100 min^-1 occurred in Aug/Sep 2000 when Galileo was at about 280 R_J from Jupiter. This peak in dust emission appears to coincide with strong changes in the release of neutral gas from the Io torus. Strong variability in the Io dust flux was measured on timescales of days to weeks, indicating large variations in the dust release from Io or the Io torus or both on such short timescales. Galileo has detected a large number of bigger micron-sized particles mostly in the region between the Galilean moons. A surprisingly large number of such bigger grains was measured in March 2003 within a 4-day interval when Galileo was outside Jupiter's magnetosphere at approximately 350 R_J jovicentric distance. Two passages of Jupiter's gossamer rings in 2002 and 2003 provided the first actual comparison of in-situ dust data from a planetary ring with the results inferred from inverting optical images.Comment: 59 pages, 13 figures, 6 tables, submitted to Planetary and Space Scienc