603 research outputs found

    Supercurrent diode effect in thin film Nb tracks

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    We demonstrate nonreciprocal critical current in 65 nm thick polycrystalline and epitaxial Nb thin films patterned into tracks. The nonreciprocal behavior gives a supercurrent diode effect, where the current passed in one direction is a supercurrent and the other direction is a normal state (resistive) current. We study the variation of the diode effect with temperature and magnetic field, and find an unexpected dependence with the width of the Nb tracks from 2-10 μ\mum. For both polycrystalline and epitaxial samples, we find that tracks of width 4 μ\mum provides the largest supercurrent diode efficiency of up to 30%\approx30\%, with the effect reducing or disappearing in the widest tracks of 10 μ\mum. It is anticipated that the supercurrent diode will become a ubiquitous component of the superconducting computer.Comment: 15 pages, 4 figure

    The clinical and cost-effectiveness of a Victim Improvement Package (VIP) for the reduction of chronic symptoms of depression or anxiety in older victims of common crime (the VIP trial): study protocol for a randomised controlled trial.

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    BACKGROUND: Older people are vulnerable to sustained high levels of psychosocial distress following a crime. A cognitive behavioural therapy (CBT)-informed psychological therapy, the Victim Improvement Package (VIP) may aid recovery. The VIP trial aims to test the clinical and cost-effectiveness of the VIP for alleviating depressive and anxiety symptoms in older victims of crime. METHODS/DESIGN: People aged 65 years or more who report being a victim of crime will be screened by Metropolitan Police Service Safer Neighbourhood Teams within a month of the crime for distress using the Patient Health Questionnaire-2 and the Generalised Anxiety Disorder-2. Those who screen positive will be signposted to their GP for assistance, and re-screened at 3 months. Participants who screen positive for depression and/or anxiety at re-screening are randomised to a CBT informed VIP added to treatment as usual (TAU) compared to TAU alone. The intervention consists of 10 individual 1-h sessions, delivered weekly by therapists from the mental health charity Mind. The primary outcome measure is the Beck Depression Inventory-II (BDI-II) and the Beck Anxiety Inventory (BAI), used as a composite measure, assessed at 6 months after the crime (post therapy) with a 9-month post-crime follow-up. Secondary outcome measures include the EQ-5D, and a modified Client Service Receipt Inventory. A total of 226 participants will be randomised VIP:TAU with a ratio 1:1, in order to detect a standardised difference of at least 0.5 between groups, using a mixed-effects linear-regression model with 90% power and a 5% significance level (adjusting for therapist clustering and potential drop-out). A cost-effectiveness analysis will incorporate intervention costs to compare overall health care costs and quality of life years between treatment arms. An embedded study will examine the impact of past trauma and engagement in safety behaviours and distress on the main outcomes. DISCUSSION: This trial should provide data on the clinical and cost-effectiveness of a CBT-informed psychological therapy for older victims of crime with anxiety and/or depressive symptoms and should demonstrate a model of integrated cross-agency working. Our findings should provide evidence for policy-makers, commissioners and clinicians responding to the needs of older victims of crime. TRIAL REGISTRATION: International Standard Randomised Controlled Trials Number, ID: ISRCTN16929670. Registered on 3 August 2016

    Distortions to the penetration depth and coherence length of superconductor/normal-metal superlattices

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    Superconducting (S) thin film superlattices composed of Nb and a normal-metal spacer (N) have been extensively utilized in Josephson junctions given their favorable surface roughness compared to Nb films of comparable thickness. In this work, we characterize the London penetration depth and Ginzburg-Landau coherence lengths of S/N superlattices using polarized neutron reflectometry and electrical transport. Despite the normal-metal spacer layers being only approximately 8% of the total superlattice thickness, we surprisingly find that the introduction of these thin N spacers between S layers leads to a dramatic increase in the measured London penetration depth compared to that of a single Nb film of comparable thickness. Using the measured values for the effective in- and out-of-plane coherence lengths, we quantify the induced anisotropy of the superlattice samples and compare to a single Nb film sample. From these results, we find that the superlattices behave similarly to layered 2D superconductors

    Probing the Spiral Magnetic Phase in 6 nm Textured Erbium using Polarised Neutron Reflectometry

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    We characterise the magnetic state of highly-textured, sputter deposited erbium for a film of thickness 6 nm. Using polarised neutron reflectometry it is found the film has a high degree of magnetic disorder, and we present some evidence that the films’ local magnetic state is consistent with bulk-like spiral magnetism. This, combined with complementary characterisation techniques, show that thin film erbium is a strong candidate material for incorporation into device structures

    Matrix metalloproteinase-9 mediated shedding of syndecan-4 in glomerular endothelial cells

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    Background - Diabetic nephropathy is the most common cause of end‐stage renal failure in the western world and Asia. The mechanisms are not fully elucidated, but disruption of glomerular endothelial glycocalyx and shedding of its components including syndecans has been implicated. Aims - We hypothesize that reduced glomerular filtration in diabetes is caused by disruption of endothelial glycocalyx in glomeruli, including increased shedding of syndecan‐4. The aim of this study was to determine the effects of experimental diabetic conditions by means of hyperglycemia and IL‐1β exposure on syndecan‐4 shedding in GEnC, and to investigate regulation of shedding by sheddases. Results - We found that in GEnC the expression of syndecan‐4 is higher than that of the other syndecans. In polarized GEnC, apical shedding of syndecan‐4 and syndecan‐4 gene expression was increased by 60% after IL‐1β‐stimulation, but not affected by hyperglycemic conditions. This was accompanied by a 50% increase in MMP9 gene expression in IL‐1β‐stimulated cells but not hyperglycemia. MMP9 knockdown reduced syndecan‐4 shedding by 50%. Conclusion - IL‐1β but not hyperglycemia increases the shedding of syndecan‐4 from GEnC in an MMP9‐dependent manner. This provides a potential mechanism of GEnC damage in diabetes and other inflammatory conditions

    Matrix metalloproteinase-9 mediated shedding of syndecan-4 in glomerular endothelial cells

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    Background - Diabetic nephropathy is the most common cause of end‐stage renal failure in the western world and Asia. The mechanisms are not fully elucidated, but disruption of glomerular endothelial glycocalyx and shedding of its components including syndecans has been implicated. Aims - We hypothesize that reduced glomerular filtration in diabetes is caused by disruption of endothelial glycocalyx in glomeruli, including increased shedding of syndecan‐4. The aim of this study was to determine the effects of experimental diabetic conditions by means of hyperglycemia and IL‐1β exposure on syndecan‐4 shedding in GEnC, and to investigate regulation of shedding by sheddases. Results - We found that in GEnC the expression of syndecan‐4 is higher than that of the other syndecans. In polarized GEnC, apical shedding of syndecan‐4 and syndecan‐4 gene expression was increased by 60% after IL‐1β‐stimulation, but not affected by hyperglycemic conditions. This was accompanied by a 50% increase in MMP9 gene expression in IL‐1β‐stimulated cells but not hyperglycemia. MMP9 knockdown reduced syndecan‐4 shedding by 50%. Conclusion - IL‐1β but not hyperglycemia increases the shedding of syndecan‐4 from GEnC in an MMP9‐dependent manner. This provides a potential mechanism of GEnC damage in diabetes and other inflammatory conditions

    Observation of anomalous Meissner screening in Cu/Nb and Cu/Nb/Co thin films

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    We have observed the spatial distribution of magnetic flux in Nb, Cu/Nb and Cu/Nb/Co thin films using muon-spin rotation. In an isolated 50 nm thick Nb film we find a weak flux expulsion (Meissner effect) which becomes significantly enhanced when adding an adjacent 40 nm layer of Cu. The added Cu layer exhibits a Meissner effect (due to induced superconducting pairs) and is at least as effective as the Nb to expel flux. These results are confirmed by theoretical calculations using the quasiclassical Green’s function formalism. An unexpected further significant enhancement of the flux expulsion is observed when adding a thin (2.4 nm) ferromagnetic Co layer to the bottom side of the Nb. This observed cooperation between superconductivity and ferromagnetism, by an unknown mechanism, forms a key ingredient for developing superconducting spintronics
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