Using NMR to Measure Fractal Dimensions

A comment is made on the recent PFG NMR measurements by Stallmach, et al. on water-saturated sands [Phys. Rev. Lett. 88, 105505 (2002)]. It is pointed out that the usual law for the time-dependent diffusion coefficient D(t) used by these authors is not valid for a fractal surface. It is shown that (1-D(t)/D0) \~ t^[(3-Ds)/2] at short times for a surface of fractal dimension Ds, where D0 is the bulk diffusion coefficient. Preliminary PFG NMR data on water saturated limestone and plastic beads are presented to illustrate this analysis.Comment: 1 page, 1 figur

Complex Memory Formation in Frictional Granular Media

Using numerical simulations it is shown that a jammed, random pack of soft frictional grains can store an arbitrary waveform that is applied as a small time-dependent shear while the system is slowly compressed. When the system is decompressed at a later time, an approximation of the input waveform is recalled in time-reversed order as shear stresses on the system boundaries. This effect depends on friction between the grains, and is independent of some aspects of the friction model. This type of memory could potentially be observable in other types of random media that form internal contacts when compressed.Comment: 8 pages, 5 figure

Functional adaptivity for digital library services in e-infrastructures: the gCube approach

We consider the problem of e-Infrastructures that wish to reconcile the generality of their services with the bespoke requirements of diverse user communities. We motivate the requirement of functional adaptivity in the context of gCube, a service-based system that integrates Grid and Digital Library technologies to deploy, operate, and monitor Virtual Research Environments defined over infrastructural resources. We argue that adaptivity requires mapping service interfaces onto multiple implementations, truly alternative interpretations of the same functionality. We then analyse two design solutions in which the alternative implementations are, respectively, full-fledged services and local components of a single service. We associate the latter with lower development costs and increased binding flexibility, and outline a strategy to deploy them dynamically as the payload of service plugins. The result is an infrastructure in which services exhibit multiple behaviours, know how to select the most appropriate behaviour, and can seamlessly learn new behaviours

Adhesive capsulitis of the shoulder: pain intensity and distribution

Purpose Papers regarding adhesive capsulitis (AC) of the shoulder focused on etiology, epidemiology, diagnosis, and treatment; until now, information on shoulder pain characteristics is still scarce. Our aim was to analyze pain intensity and distribution in patients with AC. Methods The study group was composed of 278 (133M–145F) consecutive patients with AC. After diagnosis, shoulder pain distribution was assessed through an upper limb pain map and pain intensity through a visual analog scale. Patients were distinguished on the basis of gender, age, time elapsed from onset of symptoms, and severity of functional limitation. Data were submitted to statistical analysis. Results Intensity of shoulder pain caused by AC was higher in females (p 0.05). Conclusion Shoulder pain due to AC may be influenced by gender and severity of functional limitation. AC pain distribution principally involves anterior aspect of the shoulder with downward extension of the arm until its distal third

Measurements of Grain Motion in a Dense, Three-Dimensional Granular Fluid

We have used an NMR technique to measure the short-time, three-dimensional displacement of grains in a system of mustard seeds vibrated vertically at 15g. The technique averages over a time interval in which the grains move ballistically, giving a direct measurement of the granular temperature profile. The dense, lower portion of the sample is well described by a recent hydrodynamic theory for inelastic hard spheres. Near the free upper surface the mean free path is longer than the particle diameter and the hydrodynamic description fails.Comment: 4 pages, 4 figure

NMR Investigation of the Low Temperature Dynamics of solid 4He doped with 3He impurities

The lattice dynamics of solid 4He has been explored using pulsed NMR methods to study the motion of 3He impurities in the temperature range where experiments have revealed anomalies attributed to superflow or unexpected viscoelastic properties of the solid 4He lattice. We report the results of measurements of the nuclear spin-lattice and spin-spin relaxation times that measure the fluctuation spectrum at high and low frequencies, respectively, of the 3He motion that results from quantum tunneling in the 4He matrix. The measurements were made for 3He concentrations 16<x_3<2000 ppm. For 3He concentrations x_3 = 16 ppm and 24 ppm, large changes are observed for both the spin-lattice relaxation time T_1 and the spin-spin relaxation time T_2 at temperatures close to those for which the anomalies are observed in measurements of torsional oscillator responses and the shear modulus. These changes in the NMR relaxation rates were not observed for higher 3He concentrations.Comment: 23 pages, 10 figure

Revision of the Barremian fern Coniopteris laciniata from Las Hoyas and El Montsec (Spain): Highlighting its importance in the evolution of vegetation during the Early Cretaceous

The species Coniopteris laciniata and Sphenopteris wonnacottii are heterophyllous ferns recovered from two Spanish Barremian localities, Las Hoyas and El Montsec respectively. The similarities between these species, observed in a study of a total of 66 hand specimens from both localities, indicate that they are conspecific. Following the rule of priority in botanical nomenclature, and because there are doubts about the assignment of this species to a higher taxonomic rank, the name Coniopteris is maintained. Characters of this fern and additional characters of other species of Coniopteris would support a diversification of polypod ferns during the Early Cretaceous. Metric architecture analyses suggest that the heterophylly of the plant was probably caused by the submersion of the apical part of fronds in water during their development, which would be consistent with the taphonomy of the remains in both localitiesWe would like to thank El Montsec housed at the Muséum national d’Histoire naturelle (Paris, France), which was visited with support of a grant from the SYNTHESYS Project (http://www.synthesys.info/), financed by the European Community Research Infrastructure Action under the FP7 Integrating Activities Program. Candela Blanco-Moreno is supported by a Margarita Salas Postdoc CA1/RSUE/2021-00703 scholarship funded by the Spanish Ministry of Universities and Universidad Autónoma de Madrid. This work is part of the project PID2019-105546GB-I00 of the Spanish Ministry of Science, Innovation and Universitie