Encryption – use and control in E-commerce

The author describes how cryptography can be used to address modern business requirements such as identity protection, secure web access and digital signatures. Article by Robert Bond (Head of Innovation & Technology Group, Hobson Audley and Fellow of SALS). Published in Amicus Curiae - Journal of the Institute of Advanced Legal Studies and its Society for Advanced Legal Studies. The Journal is produced by the Society for Advanced Legal Studies at the Institute of Advanced Legal Studies, University of London

Formal and informal financing in a Chicago neighborhood

This article documents not only the actual use of banks, but also the widespread use of alternative financing mechanisms, using data from a survey of households and businesses in a Hispanic neighborhood of Chicago.Bank loans ; Chicago (Ill.) ; Consumer behavior ; Mortgages

Identifying multiple detachment horizons and an evolving thrust history through cross-section restoration and appraisal in the Moine Thrust Belt, NW Scotland

Peer reviewedPublisher PD

Fluctuation dynamics of a single magnetic chain

"Tunable" fluids such as magnetorheological "MR" and electrorheological "ER" fluids are comprised of paramagnetic or dielectric particles suspended in a low-viscosity liquid. Upon the application of a magnetic or electric field, these fluids display a dramatic, reversible, and rapid increase of the viscosity. This change in viscosity can, in fact, be tuned by varying the applied field, hence the name "tunable fluids". This effect is due to longitudinal aggregation of the particles into chains in the direction of the applied field and the subsequent lateral aggregation into larger semisolid domains. A recent theoretical model by Halsey and Toor "HT" explains chain aggregation in dipolar fluids by a fluctuation-mediated long-range interaction between chains and predicts that this interaction will be equally efficient at all applied fields. This paper describes video-microscopy observations of long, isolated magnetic chains that test HT theory. The measurements show that, in contrast to the HT theory, chain aggregation occurs more efficiently at higher magnetic field strength (H0) and that this efficiency scales as H0½. Our experiments also yield the steady-state and time-dependent fluctuation spectra C(x,x')≡ [h(x)-h(x')]²>½ and C(x,x',t,t')≡ ½ for the instantaneous deviation h(x,t) from an axis parallel to the field direction to a point x on the chain. Results show that the steady-state fluctuation growth is similar to a biased random walk with respect to the interspacing ͉ |x-x'| along the chain, C(x,x')≈|x-x'| α, with a roughness exponent α =0.53±0.02. This result is partially confirmed by Monte Carlo simulations. Time-dependent results also show that chain relaxation is slowed down with respect to classical Brownian diffusion due to the magnetic chain connectivity, C(x,x',t,t')≈|t-t'|β, with a growth exponent β=0.35±0.05<½. All data can be collapsed onto a single curve according to C(x,x',t,t')≈|x-x'| α ψ (|t-t'| / |x-x'| z ), with a dynamic exponent z= α /β≅ 1.42

Evaluating the Effectiveness of Shielding Material, Vehicle Shape and Astronaut Position for Deep Space Travel

Background: As future crewed, deep space missions are being planned, it is important to assess how spacecraft design can be used to minimize radiation exposure. Collectively with shielding material, vehicle shape and astronaut position must be used to protect astronauts from the two primary sources of space radiation: Galactic Cosmic Rays (GCRs) and Solar Particle Events (SPEs). Methods: The On-Line Tool for the Assessment of Radiation in Space (OLTARIS) version 4.1 analysis package is used to evaluate and analyze this detailed radiation field. Developed by the National Aeronautics and Space Administration\u27s (NASA) Langley Research Center, the tool enables engineering and research related space radiation calculations. Each configuration is evaluated in whole body effective dose equivalent (ED). This research evaluates 70 aerospace materials, 2 vehicle shapes and 3 astronaut positions. Results and Conclusions: The material analyses show that for metals, aluminum outperforms and therefore is the most feasible metal for deep space travel. But when evaluating all materials, polyethylene outperforms all feasible aerospace materials. The vehicle shape and astronaut position analyses show that moving a human phantom closer to a wall does significantly decrease the ED. This pattern is not dependent on material nor boundary condition, but the mean shielding thickness a source ray must travel through for the GCR boundary condition. For shielding thicknesses greater than 30 g/cm 2 for polyethylene and 100g/cm 2 for aluminum, the results suggest that having astronauts’ habitats and work areas located further from the center will help protect astronauts longer from deep space radiation.https://scholarscompass.vcu.edu/gradposters/1067/thumbnail.jp

Implications of heterogeneous fracture distribution on reservoir quality; an analogue from the Torridon Group sandstone, Moine Thrust Belt, NW Scotland

This research was funded by a NERC CASE studentship (NERC code NE/I018166/1) in partnership with Midland Valley. Midland Valley's Move software was used for cross section construction and strain modelling. 3D Field software is acknowledged for contour map creation. Mark Cooper is thanked for constructive comments. Steven Laubach and Bill Dunne are thanked overseeing the editorial process and Magdalena Ellis Curry, Bertrand Gauthier and Arthur Lavenu are thanked for constructive reviews.Peer reviewedPublisher PD

OCD as a Dynamical Disease and the Familial Context of Ritual Rigidity: A Nonlinear Dynamics Perspective

Comparatively few studies of obsessive compulsive disorder (OCD) have addressed the interpersonal dynamical patterns within families that could exacerbate or quell symptom severity in the ill relatives or hypothesize other roles for familial variables. Furthermore, the extant studies have relied primarily upon linear models. Methodological limitations of linear models, such as assuming that change occurs as the result of unidirectional influences and that the scores obtained for each variable are independent of each other are at variance with temporal, dynamic phenomena and have restricted the empirical investigations of the dynamics of OCD. The current study investigated whether OCD could be considered a dynamical disease such that the complex rhythmic processes that are the norm for living things would be replaced by relatively constant dynamics or by periodic dynamics. Determining whether OCD could be a dynamical disease could improve our current treatment strategies or lead to the development of new treatment strategies, by finding ways to best control or alter the dynamics of the family system and determining when the best time for change could take place. To accomplish this, this study analyzed both the occurrence of rituals as they transpired over time and the influence the family may have had upon the spatiotemporal structure of symptoms. This information was obtained by using the time-diary method and comparing the time-series of 17 clinical cases with 16 matched controls. Comparisons of nonlinear regression parameters and Lyapunov exponents revealed that OCD exhibited a low-dimensional deterministic structure. The average nonlinear model (R2 = 0.32) explained more than 10 times the variance of its linear counterpart (R2 = 0.03). Family reactions and emotional responses accounted for only a very modest increase in the variance explained by the nonlinear regression model or in the amount of turbulence. Family reactions and emotional responses do little to make the rituals go away, but instead may strengthen the dynamics. Finally, significant rank order correlations were found between the R2 for each logbook and Lyapunov exponents with symptom severity and family reactions. Theoretical and practical implications of the results are discussed, including implications for treatment

Results of a sub-scale model rotor icing test

A heavily instrumented sub-scale model of a helicopter main rotor was tested in the NASA Lewis Research Center Icing Research Tunnel (IRT) in September and November 1989. The four-bladed main rotor had a diameter of 1.83 m (6.00 ft) and the 0.124 m (4.9 in) chord rotor blades were specially fabricated for this experiment. The instrumented rotor was mounted on a Sikorsky Aircraft Powered Force Model, which enclosed a rotor balance and other measurement systems. The model rotor was exposed to a range of icing conditions that included variations in temperature, liquid water content, and median droplet diameter, and was operated over ranges of advance ratio, shaft angle, tip Mach number (rotor speed) and weight coefficient to determine the effect of these parameters on ice accretion. In addition to strain gage and balance data, the test was documented with still, video, and high speed photography, ice profile tracings, and ice molds. The sensitivity of the model rotor to the test parameters, is given, and the result to theoretical predictions are compared. Test data quality was excellent, and ice accretion prediction methods and rotor performance prediction methods (using published icing lift and drag relationships) reproduced the performance trends observed in the test. Adjustments to the correlation coefficients to improve the level of correlation are suggested

Influence of structural position on fracture networks in the Torridon Group, Achnashellach fold and thrust belt, NW Scotland

Acknowledgements This research is funded by a NERC CASE studentship (NERC code NE/I018166/1) in partnership with Midland Valley. The authors thank Midland Valley for use of FieldMove Clino software for fracture data collection, and Move software for cross section construction, and strain modelling. 3D Field software is acknowledged for contour map creation. We also thank Toru Takeshita for overseeing the editorial process, and Catherine Hanks and Ole Petter Wennberg for constructive reviews.Peer reviewedPublisher PD