13 research outputs found

    Temperature and magnetic-field dependence of the conductivity of YBaCuO films in the vicinity of superconducting transition: Effect of Tc-inhomogeneity

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    Temperature and magnetic field dependences of the conductivity of YBaCuO films in the transition region are analyzed taking into account spatial inhomogeneity in transition temperature, Tc. (i) An expression for the superconducting contribution to conductivity, \sigma_s(T,H,Tc), of a homogeneous superconductor for H<<Hc2(T=0) is obtained using the solution of the Ginzburg-Landau equation in form of perturbation expansions [S.Ullah, A.T.Dorsey, PRB 44, 262 (1991)]. (ii) The error in \sigma_s(T,H,Tc) occurring due to the presence of Tc-inhomogeneity is calculated and plotted on an H-T plane diagram. These calculations use an effective medium approximation and a Gaussian distribution of Tc. (iii) Measuring the temperature dependences of a voltage, induced by a focused electron beam, we determine spatial distributions of the critical temperature for YBaCuO microbridges with a 2 micron resolution. A typical Tc-distribution dispersion is found to be approximately 1K. For such dispersion, error in \sigma_s(T,H,Tc) due to Tc-inhomogeneity exceeds 30% for magnetic fields H < 1 T and temperatures |T-Tc| < 0.5 K. (iv) Experimental R(T,H) dependences of resistance are well described by a numerical solution of a set of Kirchoff equations for the resistor network based on the measured spatial distributions of Tc and the expression for \sigma_s(T,H,Tc).Comment: REVTeX, 12 pages including 7 figures, resubmitted to Phys. Rev.

    Effectiveness and Safety of Adalimumab Biosimilar SB5 in IBD:Outcomes in Originator to SB5 Switch, Double Biosimilar Switch and Bio-Naieve SB5 Observational Cohorts

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    BACKGROUND AND AIMS: Multiple adalimumab [ADA] biosimilars are now approved for use in inflammatory bowel disease [IBD]; however, effectiveness and safety data remain scarce. We aimed to investigate long-term outcomes of the ADA biosimilar SB5 in IBD patients following a switch from the ADA originator [SB5-switch cohort] or after start of SB5 [SB5-start cohort]. METHODS: We performed an observational cohort study in a tertiary IBD referral centre. All IBD patients treated with Humira underwent an elective switch to SB5. We identified all these patients in a biological prescription database that prospectively registered all ADA start and stop dates including brand names. Data on IBD phenotype, C-reactive protein [CRP], drug persistence, ADA drug and antibody levels, and faecal calprotectin were collected. RESULTS: In total, 481 patients were treated with SB5, 256 in the SB5-switch cohort (median follow-up: 13.7 months [IQR 8.6–15.2]) and 225 in the SB5-start cohort [median follow-up: 8.3 months [4.2–12.8]). Of the SB5-switch cohort, 70.8% remained on SB5 beyond 1 year; 90/256 discontinued SB5, mainly due to adverse events [46/90] or secondary loss of response [37/90]. In the SB5-start cohort, 81/225 discontinued SB5, resulting in SB5-drug persistence of 60.3% beyond 1 year. No differences in clinical remission [p = 0.53], CRP [p = 0.80], faecal calprotectin [p = 0.40] and ADA trough levels [p = 0.55] were found between baseline, week 26 and week 52 following switch. Injection site pain was the most frequently reported adverse event. CONCLUSION: Switching from ADA originator to SB5 appeared effective and safe in this study with over 12 months of follow-up

    Inferring connection proximity in networks of electrically coupled cells by subthreshold frequency response analysis

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    Electrical synapses continuously transfer signals bi-directionally from one cell to another, directly or indirectly via intermediate cells. Electrical synapses are common in many brain structures such as the inferior olive, the subcoeruleus nucleus and the neocortex, between neurons and between glial cells. In the cortex, interneurons have been shown to be electrically coupled and proposed to participate in large, continuous cortical syncytia, as opposed to smaller spatial domains of electrically coupled cells. However, to explore the significance of these findings it is imperative to map the electrical synaptic microcircuits, in analogy with in vitro studies on monosynaptic and disynaptic chemical coupling. Since "walking" from cell to cell over large distances with a glass pipette is challenging, microinjection of (fluorescent) dyes diffusing through gap-junctions remains so far the only method available to decipher such microcircuits even though technical limitations exist. Based on circuit theory, we derive analytical descriptions of the AC electrical coupling in networks of isopotential cells. We then suggest an operative electrophysiological protocol to distinguish between direct electrical connections and connections involving one or more intermediate cells. This method allows inferring the number of intermediate cells, generalizing the conventional coupling coefficient, which provides limited information. We validate our method through computer simulations, theoretical and numerical methods and electrophysiological paired recordings. \ua9 Springer Science+Business Media, LLC 2007
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