Is simultaneous yy and ξ\xi--scaling in the quasi-elastic region accidental?

We study the $y$ and $\xi$--scaling of the nuclear response at large momentum transfer in order to understand how scaling based on very different descriptions of the elementary interaction can occur simultaneously. We find that the approximate validity of $\xi$-scaling at low energy loss arises from the coincidental behavior of the quasielastic and deep inelastic cross sections.Comment: 4 pages, 3 Postscript figure

Alternative determinism principle for topological analysis of chaos

The topological analysis of chaos based on a knot-theoretic characterization of unstable periodic orbits has proved a powerful method, however knot theory can only be applied to three-dimensional systems. Still, the core principles upon which this approach is built, determinism and continuity, apply in any dimension. We propose an alternative framework in which these principles are enforced on triangulated surfaces rather than curves and show that in dimension three our approach numerically predicts the correct topological entropies for periodic orbits of the horseshoe map.Comment: Accepted for publication as Rapid Communication in Physical Review

Measurement of the SOC State Specific Heat in ^4He

When a heat flux Q is applied downward through a sample of liquid 4He near the lambda transition, the helium self organizes such that the gradient in temperature matches the gravity induced gradient in Tlambda. All the helium in the sample is then at the same reduced temperature tSOC = ((T[sub SOC] - T[sub lambda])/T[sub lambda]) and the helium is said to be in the Self-Organized Critical (SOC) state. We have made preliminary measurements of the 4He SOC state specific heat, C[del]T(T(Q)). Despite having a cell height of 2.54 cm, our results show no difference between C[del]T and the zero-gravity 4He specific heat results of the Lambda Point Experiment (LPE) [J.A. Lipa et al., Phys. Rev. B, 68, 174518 (2003)] over the range 250 to 450 nK below the transition. There is no gravity rounding because the entire sample is at the same reduced temperature tSOC(Q). Closer to Tlambda the SOC specific heat falls slightly below LPE, reaching a maximum at approximately 50 nK below Tlambda, in agreement with theoretical predictions [R. Haussmann, Phys. Rev. B, 60, 12349 (1999)]

Superconducting On-chip Fourier Transform Spectrometer

The kinetic inductance effect is strongly nonlinear with applied current in NbTiN, TiN and NbN thin films. This can be utilized to realize novel devices. We present results from transmission lines made with these materials, where DC (current) control is used to modulate the phase velocity thereby enabling on-chip spectrometers. Utility of such compact spectrometers is discussed, along with their natural connection with parametric amplifiers

Is the Yb2Ti2O7 pyrochlore a quantum spin ice?

We use numerical linked cluster (NLC) expansions to compute the specific heat, C(T), and entropy, S(T), of a quantum spin ice model of Yb2Ti2O7 using anisotropic exchange interactions recently determined from inelastic neutron scattering measurements and find good agreement with experimental calorimetric data. In the perturbative weak quantum regime, this model has a ferrimagnetic ordered ground state, with two peaks in C(T): a Schottky anomaly signalling the paramagnetic to spin ice crossover followed at lower temperature by a sharp peak accompanying a first order phase transition to the ferrimagnetic state. We suggest that the two C(T) features observed in Yb2Ti2O7 are associated with the same physics. Spin excitations in this regime consist of weakly confined spinon-antispinon pairs. We suggest that conventional ground state with exotic quantum dynamics will prove a prevalent characteristic of many real quantum spin ice materials.Comment: 8 pages (two-column), 9 figure

Parents understanding of vitamin D requirements, and the use of fortified foods

One in four toddlers are not achieving the recommended vitamin D intake crucial for their healthy development(1, 2). This study explored parents’ acceptability of factors affecting purchasing of foods and drinks fortified with Vitamin D in children aged 0-2 years old. A total of 194 parents completed an online parent questionnaire. Focus groups and interviews were used to explore in depth perceptions of vitamin D fortification. Thirteen participants participated in the 5 focus groups, 5 completed interviews. The majority of participants were female (mothers) and of White-British ethnic background, aged between 25-40 years, with 89% of the sample with a level 3 qualification (e.g. 2 or more A levels, NVQ level 3). Basic descriptive statistics were calculated from the questionnaire data and a thematic analysis methodology was applied to the qualitative data. The findings indicated low purchasing of vitamin D fortified foods/drinks by parents (21% of the sample). The foods/drinks most purchased were cereal, yogurts and alternative milks. Willingness to purchase certain products fortified with vitamin D to increase their child’s vitamin D was however high. After excluding formula milk, parents would be willing to buy yogurt, yogurt drinks, cereals, milk-based drinks, fruit juice and margarine. The table outlines parents’ views on the facilitators and barriers to purchasing vitamin D fortified foods and drinks. There is a potential for fortified foods to play a role in increasing the intake of vitamin D intake. Parents need quality education explaining the need to prevent vitamin D deficiency, though fortified products. Products also need to be suitable for babies and toddlers; better labelled, lower cost; with healthy options available with lower sugar and salt content, tasty, longer shelf life and better availability in local shops and supermarkets. Future research should determine if consumption of fortified foods/drinks alone rather than supplementation is sufficient to meet children’s daily intake of vitamin D(3)