Magnetic skin effect in Pb(Fe _{1/2}$Nb _{1/2}$)O3.

Relaxor-ferroelectrics display exceptional dielectric properties resulting from the underlying random dipolar fields induced by strong chemical inhomogeneity. An unusual structural aspect of relaxors is a skin-effect where the near-surface region in single crystals exhibit structures and critical phenomena that differ from the bulk. Relaxors are unique in that this skin effect extends over a macroscopic lengthscale of ∼100 µmwhereas usual surface layers only extend over a few unit cells (or ∼nm). We present a muon spectroscopy study of Pb(Fe_{1/2}Nb_{1/2})O3(PFN) which displays ferroelectric order, including many relaxor-like dielectric properties such as a frequency broadened dielectric response, and antiferromagnetism with spatially short-range polar correlations and hence can be termed a multiferroic. In terms of the magnetic behavior determined by the Fe3+(S=5/2,L ≈ 0) ions, PFN has been characterized as a unique example of a 'cluster spin-glass'. We use variable momentum muon spectroscopy to study the depth dependence of the slow magnetic relaxations in a large 1 cm3crystal of PFN. Zero-fieldpositivemuon spin relaxation is parameterized using a stretched exponential, indicative of a distribution of relaxation rates of the Fe3+spins. This bandwidth of frequencies changes as a function of muon momentum, indicative of a change in the Fe3+relaxation rates as a function of muon implantation depth in our single crystal. Usingnegativemuon elemental analysis, we find small-to-no measurable change in the Fe3+/Nb5+concentration with depth implying that chemical concentration alone cannot account for the change in the relaxational dynamics. PFN displays an analogous magnetic skin effect reported to exist in the structural properties of relaxor-ferroelectrics.

Development and validation of a questionnaire to assess owner and canine quality-of-life and treatment satisfaction in canine allergic dermatitis.

BACKGROUND: Animal and owner quality-of-life (QoL) is pivotal in treatment decisions. Accurate measurement of owner-reported QoL and treatment satisfaction (TS) supports disease burden and treatment benefit evaluation. OBJECTIVES: Develop and evaluate an owner-completed canine dermatitis QoL and TS questionnaire (CDQoL-TSQ) in allergic dogs. MATERIALS AND METHODS: The CDQoL-TSQ was drafted following review of existing measures and expert input. Content validity was assessed through interviews with owners of allergic dogs. Psychometric properties of the QoL domains (Canine QoL, Owner QoL) were evaluated. Score interpretation was derived. RESULTS: Twenty dog owners were interviewed. Item wording was amended following the first 10 interviews. Data from 211 owners were used in the psychometric evaluation. The Canine QoL domain demonstrated strong internal consistency (α = 0.89), test-retest reliability (ICC2,1 = 0.844), moderate convergent validity (r = 0.41) and moderate-high known-groups validity (effect size 0.37-0.64). The Owner QoL domain demonstrated strong internal consistency (α = 0.73), high convergent validity (r = 0.63) and moderate-high known-groups validity (0.43-0.63). Test-retest reliability approached moderate strength (ICC2,1 = 0.490). Group-level interpretation analysis showed minimal important difference of 7.0-13.6 points for dogs and 13.0-13.6 for owners. For individual dogs a change of 6.3 or 12.5 points for dogs, and 12.5 or 18.8 for owners indicates a response. CONCLUSIONS AND CLINICAL RELEVANCE: The CDQOL-TSQ is a two-part assessment to evaluate QoL and TS in canine allergic dermatitis. The QoL questionnaire demonstrated validity and reliability, and interpretation of scores was derived, making it suitable for use in research and practice. The TS module is suitable for clinical setting use to improve owner-veterinarian communication.