Superconductivity in an Einstein Solid AxV2Al20 (A = Al and Ga)

A cage compound AxV2Al20 (Al10V), that was called an Einstein solid by Caplin and coworkers 40 years ago, is revisited to investigate the low-energy, local vibrations of the A atoms and their influence on the electronic and superconducting properties of the compound. Polycrystalline samples with A = Al, Ga, Y, and La are studied through resistivity and heat capacity measurements. Weak-coupling BCS superconductivity is observed below Tc = 1.49, 1.66, and 0.69 K for Ax = Al0.3, Ga0.2, and Y, respectively, but not above 0.4 K for Ax = La. Low-energy modes are detected only for A = Al and Ga, which are approximately described by the Einstein model with Einstein temperatures of 24 and 8 K, respectively. A weak but significant coupling between the low-energy modes, which are almost identical to those called rattling in recent study, and conduction electrons manifests itself as anomalous enhancement in resistivity at around low temperatures corresponding to the Einstein temperatures.Comment: 12 pages, 5 figures, to be published in J. Phys. Soc. Jp

Mapping the dynamic interactions between vortex species in highly anisotropic superconductors

Here we use highly sensitive magnetisation measurements performed using a Hall probe sensor on single crystals of highly anisotropic high temperature superconductors $Bi_{2}Sr_{2}CaCu_{2}O_{8}$ to study the dynamic interactions between the two species of vortices that exist in such superconductors. We observe a remarkable and clearly delineated high temperature regime that mirrors the underlying vortex phase diagram. Our results map out the parameter space over which these dynamic interaction processes can be used to create vortex ratchets, pumps and other fluxonic devices.Comment: 7 pages, 3 figures, to be published in Supercond. Sci. Techno

Anisotropies of the lower and upper critical fields in MgB2_2 single crystals

The temperature dependence of the London penetration depth ($\lambda$) and coherence length ($\xi$) has been deduced from Hall probe magnetization measurements in high quality MgB$_2$ single crystals in the two main crystallographic directions. We show that, in contrast to conventional superconductors, MgB$_2$ is characterized by two different anisotropy parameters ($\Gamma_\lambda = \lambda_c/\lambda_{ab}$ and $\Gamma_\xi = \xi_{ab}/\xi_c$) which strongly differ at low temperature and merge at $T_c$. These results are in very good agreement with recent calculations in weakly coupled two bands suprerconductors (Phys. Rev. B, 66, 020509(R) (2002).Comment: 4 pages, 4 figure

First order magnetic transition in CeFe2_2 alloys: Phase-coexistence and metastability

First order ferromagnetic (FM) to antiferromagnetic (AFM) phase transition in doped-CeFe$_2$ alloys is studied with micro-Hall probe technique. Clear visual evidence of magnetic phase-coexistence on micrometer scales and the evolution of this phase-coexistence as a function of temperature, magnetic field and time across the first order FM-AFM transition is presented. Such phase-coexistence and metastability arise as natural consequence of an intrinsic disorder-influenced first order transition. Generality of this phenomena involving other classes of materials is discussed.Comment: 11 pages of text and 3 figure

Effects of Aerobic Exercise Training on Daily Psychological Processes in Family Caregivers: Secondary Analyses of a Randomized Controlled Trial

The aim of this study was to examine the effects of a 24-week aerobic exercise training program on daily psychological processes and occurrence of stressors in a group of previously physically underactive family caregivers of patients with dementia. As part of the Fitness, Aging, and STress (FAST) randomized controlled trial, 68 participants (F = 55; M = 13) were randomized to either a staff-supported, 24-week aerobic training (N = 34) program or waitlist control (N = 34) group. Approximately 2 weeks prior to randomization, ecological momentary assessments were completed 6 times per day for 7 days and again in the 24th week of the trial to assess exposure to levels of momentary positive affect, negative affect, rumination, control, and the occurrence of stressors throughout the day. These secondary analyses with data from 56 of the participants revealed that the intervention group showed a significantly larger increase in daily positive affect and perceptions of control compared to control participants over the course of the intervention. A treatment effect was also found for negative affect and rumination, whereby both decreased to a greater extent in the intervention group when compared with participants in the control condition. The 24-week aerobic training program had significant impacts on daily psychological processes in family caregivers, deepening our understanding of the robust effects of exercise on mental health

Evidence for Nodal superconductivity in Sr2_{2}ScFePO3_{3}

Point contact Andreev reflection spectra have been taken as a function of temperature and magnetic field on the polycrystalline form of the newly discovered iron-based superconductor Sr2ScFePO3. A zero bias conductance peak which disappears at the superconducting transition temperature, dominates all of the spectra. Data taken in high magnetic fields show that this feature survives until 7T at 2K and a flattening of the feature is observed in some contacts. Here we inspect whether these observations can be interpreted within a d-wave, or nodal order parameter framework which would be consistent with the recent theoretical model where the height of the P in the Fe-P-Fe plane is key to the symmetry of the superconductivity. However, in polycrystalline samples care must be taken when examining Andreev spectra to eliminate or take into account artefacts associated with the possible effects of Josephson junctions and random alignment of grains.Comment: Published versio

Safety, tolerability and clinical implementation of 'ready-to-use' 68gallium-DOTA0-Tyr3-octreotide (68Ga-DOTATOC) (SomaKIT TOC) for injection in patients diagnosed with gastroenteropancreatic neuroendocrine tumours (GEP-NETs)

BACKGROUND: 68Ga-DOTA0-Tyr3-octreotide (68Ga-DOTATOC) positron emission tomography-CT (PET-CT) has superior diagnostic performance compared to the licensed tracer OctreoScan single photon emission CT-CT in patients with gastroenteropancreatic neuroendocrine tumours (GEP-NETs). A new preparation of 68Ga-DOTATOC using a new 'ready-to-use' 68Ga-DOTATOC formulation for injection has been developed (68Ga-DOTATOC (SomaKIT TOC)). OBJECTIVES: This study aimed to assess the safety and tolerability of 68Ga-DOTATOC (SomaKIT TOC) and evaluate the feasibility and robustness of implementing it in a NET clinical imaging service. METHODS: A first-in-human phase I/II multicentre, open-label study of a single dose of 68Ga-DOTATOC (SomaKIT TOC) 2 MBq/kg±10% (range 100-200 MBq) in patients with biopsy-proven grade 1-2 GEP-NETs. PET-CT was performed post injection. Patients were followed up for 28 days. We next implemented this new synthesis methodology in a clinical service assessed over 11 months. RESULTS: Twenty consenting patients were recruited; 14 males, 6 females; mean (SD) age 58 years (12); NET grade 1 (70%), grade 2 (30%); and 75% with stage IV disease. Twelve patients experienced at least one adverse event (AE) during the study with no grade 3-4 toxicities. Only four AEs were classified as possibly (headache (n=1; 4%), nausea (1; 4%)) or probably (dysgeusia (1; 4%), paraesthesia (1; 4%)) related to the study preparation. One hundred thirteen vials of 68Ga-DOTATOC (SomaKIT TOC) were synthesised with the 'kit' over a period of 11 months for clinical utility. Only 2/113 vials (1.77%) were rejected. CONCLUSIONS: The new ready-to-use preparation of 68Ga-DOTATOC (SomaKIT TOC) for injection was safe and well tolerated. This has led to the world's first (EMA) licensed 68Ga-DOTATOC (SomaKIT TOC) radiopharmaceutical for the utility of PET imaging in patients with NETs. This preparation can be robustly implemented into routine clinical practice