Disordered asymmetric simple exclusion process: mean-field treatment

We provide two complementary approaches to the treatment of disorder in a fundamental nonequilibrium model, the asymmetric simple exclusion process. Firstly, a mean-field steady state mapping is generalized to the disordered case, where it provides a mapping of probability distributions and demonstrates how disorder results in a new flat regime in the steady state current--density plot for periodic boundary conditions. This effect was earlier observed by Tripathy and Barma but we provide treatment for more general distributions of disorder, including both numerical results and analytic expressions for the width $2\Delta_C$ of the flat section. We then apply an argument based on moving shock fronts to show how this leads to an increase in the high current region of the phase diagram for open boundary conditions. Secondly, we show how equivalent results can be obtained easily by taking the continuum limit of the problem and then using a disordered version of the well-known Cole--Hopf mapping to linearize the equation. Within this approach we show that adding disorder induces a localization transformation (verified by numerical scaling), and $\Delta_C$ maps to an inverse localization length, helping to give a new physical interpretation to the problem.Comment: 13 pages, 16 figures. Submitted to Phys. Rev.

Detailed Comparison of Next-to-Leading Order Predictions for Jet Photoproduction at HERA

The precision of new HERA data on jet photoproduction opens up the possibility to discriminate between different models of the photon structure. This requires equally precise theoretical predictions from perturbative QCD calculations. In the past years, next-to-leading order calculations for the photoproduction of jets at HERA have become available. Using the kinematic cuts of recent ZEUS analyses, we compare the predictions of three calculations for different dijet and three-jet distributions. We find that in general all three calculations agree within the statistical accuracy of the Monte Carlo integration yielding reliable theoretical predictions. In certain restricted regions of phase space, the calculations differ by up to 5%.Comment: 10 pages, 7 eps-figures. To appear in the Proceedings of the Workshop on ``Monte Carlo Generators for HERA Physics'', Hamburg 1998/9

Phase 2 and 3 wind tunnel tests of the J-97 powered, external augmentor V/STOL model

Static and forward speed tests were made in a 40 multiplied by 80 foot wind tunnel of a large-scale, ejector-powered V/STOL aircraft model. Modifications were made to the model following earlier tests primarily to improve longitudinal acceleration capability during transition from hovering to wingborne flight. A rearward deflection of the fuselage augmentor thrust vector was shown to be beneficial in this regard. Other augmentor modifications were tested, notably the removal of both endplates, which improved acceleration performance at the higher transition speeds. The model tests again demonstrated minimal interference of the fuselage augmentor on aerodynamic lift. A flapped canard surface also showed negligible influence on the performance of the wing and of the fuselage augmentor

Simultaneous calculation of the helical pitch and the twist elastic constant in chiral liquid crystals from intermolecular torques

We present a molecular simulation method that yields simultaneously the equilibrium pitch wave number q and the twist elastic constant K2 of a chiral nematic liquid crystal by sampling the torque density. A simulation of an untwisted system in periodic boundary conditions gives the product K2q; a further simulation with a uniform twist applied provides enough information to separately determine the two factors. We test our new method for a model potential, comparing the results with K2q from a thermodynamic integration route, and with K2 from an order fluctuation analysis. We also present a thermodynamic perturbation theory analysis valid in the limit of weak chirality

Comparing Wearer DNA Sample Collection Methods for the Recovery of Single Source Profiles

Wearer DNA is the deposit of epithelial cells on clothing worn by an individual. Detection of the last individual to handle or wear an item is often an important and desirable determination in forensic science. The most commonly used collection methods for wearer DNA include swabbing and scraping. These often result in mixture profiles. Recently, adhesives have been introduced as a possible reliable method for the collection of biological evidence. The goal of the research was to compare the current collection methods of swabbing and scraping with a gel film called Gel-Pak ‘0’ which shares similar properties with adhesives. Gel-Pak ‘0’ has been previously studied in comparison to other adhesives for the collection of epithelial cells, and was shown to recover the top layer of loose particulate. This particulate had a tendency to be deposited by the individual who last came in contact with an item. Therefore, in comparison to the other two collection methods, Gel-Pak ‘0’ was hypothesized to recover single source profiles on clothing items from the most recent wearer. DNA analysis was performed on samples collected by the three methods from various clothing items including baseball hats, t-shirts, sweatpants, socks, and other items commonly submitted to crime labs for DNA analysis. The habitual wearer and the second/last wearer wore each item for a predetermined amount of time. The results of the research showed that Gel-Pak ‘0’ recovered a similar number of CODIS (local and national) eligible profiles as swabbing. However, coupled with the fact that it is time consuming, costly, and cannot be used on all surfaces, Gel-Pak ‘0’ was determined to not make for an effective collection method of the most recent wearer’s DNA. Therefore, Gel-Pak ‘0’ will not be considered for casework. Although Gel-Pak ‘0’ will not be further used, the results did reveal some trends that may shed light on how DNA analysts may approach wearer DNA cases. Swabbing had a tendency to yield smaller amounts of DNA in comparison to scraping, but obtain DNA from the last wearer of the piece of clothing more effectively than the other two methods. Scraping had a tendency to yield greater quantities of DNA, recovering more DNA from the habitual wearer due to its invasive nature. Revealing individuals who last wore an item can be of great importance in forensic science, and therefore, further research with various adhesives and gel films could be vital for solving forensic investigations

Heavy Quark Production in Deep-Inelastic Scattering at HERA

We discuss two topics in the production of heavy quarks in deep-inelastic scattering: the next-to-leading order Monte-Carlo HVQDIS and the next-to-leading logarithmic resummation of soft gluon effects, including estimates of next-to-next-to-leading order corrections therefrom.Comment: 10 pages, 10 figures, To appear in Proceedings of Monte Carlo Generators for HERA Physics, Hamburg 1998/99 Figures update