Vortex-unbinding and finite-size effects in Tl2Ba2CaCu2O8 thin films

Current-voltage ($I$-$V$) characteristics of Tl$_2$Ba$_2$CaCu$_2$O$_8$ thin films in zero magnetic field are measured and analyzed with the conventional Kosterlitz-Thouless-Berezinskii (KTB) approach, dynamic scaling approach and finite-size scaling approach, respectively. It is found from these results that the $I$-$V$ relation is determined by the vortex-unbinding mechanism with the KTB dynamic critical exponent $z=2$. On the other hand, the evidence of finite-size effect is also found, which blurs the feature of a phase transition.Comment: Typo corrected & reference adde

Renormalization Group Study of the Intrinsic Finite Size Effect in 2D Superconductors

Vortices in a thin-film superconductor interact logarithmically out to a distance on the order of the two-dimensional (2D) magnetic penetration depth $\lambda_\perp$, at which point the interaction approaches a constant. Thus, because of the finite $\lambda_\perp$, the system exhibits what amounts to an {\it intrinsic} finite size effect. It is not described by the 2D Coulomb gas but rather by the 2D Yukawa gas (2DYG). To study the critical behavior of the 2DYG, we map the 2DYG to the massive sine-Gordon model and then perform a renormalization group study to derive the recursion relations and to verify that $\lambda_\perp$ is a relevant parameter. We solve the recursion relations to study important physical quantities for this system including the renormalized stiffness constant and the correlation length. We also address the effect of current on this system to explain why finite size effects are not more prevalent in experiments given that the 2D magnetic penetration depth is a relevant parameter.Comment: 8 pages inRevTex, 5 embedded EPS figure

Dynamic Impedance of Two-Dimensional Superconducting Films Near the Superconducting Transition

The sheet impedances, Z(w,T), of several superconducting a-Mo77Ge23 films and one In/InOx film have been measured in zero field using a two-coil mutual inductance technique at frequencies from 100 Hz to 100 kHz. Z(w,T) is found to have three contributions: the inductive superfluid, renormalized by nonvortex phase fluctuations; conventional vortex-antivortex pairs, whose contribution turns on very rapidly just below the usual Kosterlitz-Thouless-Berezinskii unbinding temperature; and an anomalous contribution. The latter is predominantly resistive, persists well below the KTB temperature, and is weakly dependent on frequency down to remarkably low frequencies, at least 100 Hz. It increases with T as e-U'(T)/kT, where the activation energy, U'(T), is about half the energy to create a vortex-antivortex pair, indicating that the frequency dependence is that of individual excitations, rather than critical behavior.Comment: 10 pages, 10 figs; subm PR

Anomalous finite-size effect in superconducting Josephson junction arrays

We report large-scale simulations of the resistively-shunted Josephson junction array in strip geometry. As the strip width increases, the voltage first decreases following the dynamic scaling ansatz proposed by Minnhagen {\it et al.} [Phys. Rev. Lett. {\bf 74}, 3672 (1995)], and then rises towards the asymptotic value predicted by Ambegaokar {\it et al.} [Phys. Rev. Lett. {\bf 40}, 783 (1978)]. The nonmonotonic size-dependence is attributed to shortened life time of free vortices in narrow strips, and points to the danger of single-scale analysis applied to a charge-neutral superfluid state.Comment: 4 pages, 2 figure

The Current-Temperature Phase Diagram of Layered Superconductors

The behavior of clean layered superconductors in the presence of a finite electric current and in zero-magnetic field behavior is addressed. The structure of the current temperature phase diagram and the properties of each of the four regions will be explained. We will discuss the expected current voltage and resistance characteristics of each region as well as the effects of finite size and weak disorder on the phase diagram. In addition, the reason for which a weakly non-ohmic region exists above the transition temperature will be explained.Comment: 8 pages (RevTeX), 4 encapsulated postscript figure

Temperature and Frequency Dependence of Complex Conductance of Ultrathin YBa2Cu3O7-x Films: A Study of Vortex-Antivortex Pair Unbinding

We have studied the temperature dependencies of the complex sheet conductance of 1-3 unit cell (UC) thick YBa2Cu3O7-x films sandwiched between semiconducting Pr0.6Y0.4Ba2Cu3O7-x layers at high frequencies. Experiments have been carried out in a frequency range between: 2 - 30 MHz with one-spiral coil technique, 100 MHz - 1 GHz frequency range with a new technique using the spiral coil cavity and at 30 GHz by aid of a resonant cavity technique. The real and imaginary parts of the mutual-inductance between a coil and a film were measured and converted to complex conductivity by aid of the inversion procedure. We have found a quadratic temperature dependence of the kinetic inductance, L_k^-1(T), at low temperatures independent of frequency, with a break in slope at T^dc_BKT, the maximum of real part of conductance and a large shift of the break temperature and the maximum position to higher temperatures with increasing frequency. We obtain from these data the universal ratio T^dc_BKT/L_k^-1(T^dc_BKT) = 25, 25, and 17 nHK for 1-, 2- and 3UC films, respectively in close agreement with theoretical prediction of 12 nHK for vortex-antivortex unbinding transition. The activated temperature dependence of the vortex diffusion constant was observed and discussed in the framework of vortex-antivortex pair pinning. PACS numbers: 74.80.Dm, 74.25.Nf, 74.72.Bk, 74.76.BzComment: PDF file, 10 pages, 6 figures, to be published in J. Low Temp. Phys.; Proc. of NATO ARW: VORTEX 200

Dynamic scaling for 2D superconductors, Josephson junction arrays and superfluids

The value of the dynamic critical exponent $z$ is studied for two-dimensional superconducting, superfluid, and Josephson Junction array systems in zero magnetic field via the Fisher-Fisher-Huse dynamic scaling. We find $z\simeq5.6\pm0.3$, a relatively large value indicative of non-diffusive dynamics. Universality of the scaling function is tested and confirmed for the thinnest samples. We discuss the validity of the dynamic scaling analysis as well as the previous studies of the Kosterlitz-Thouless-Berezinskii transition in these systems, the results of which seem to be consistent with simple diffusion ($z=2$). Further studies are discussed and encouraged.Comment: 19 pages in two-column RevTex, 8 embedded EPS figure

The Changing Face of Drug-induced Adrenal Insufficiency in the Food and Drug Administration Adverse Event Reporting System

Context: Adrenal insufficiency (AI) is a life-threatening condition complicating heterogeneous disorders across various disciplines, with challenging diagnosis and a notable drug-induced component. Objective: This work aimed to describe the spectrum of drug-induced AI through adverse drug event reports received by the US Food and Drug Administration (FDA). Methods: A retrospective disproportionality analysis reporting trends of drug-induced AI was conducted on the FDA Adverse Event Reporting System (FAERS) (> 15 000 000 reports since 2004). AE reports were extracted from FAERS over the past 2 decades. Interventions included cases containing any of the preferred terms in the Medical Dictionary for Regulatory Activities describing AI, and signals of disproportionate reporting for drugs recorded in 10 or more cases as primary suspect. Results: We identified 8496 cases of AI: 97.5% serious, 41.1% requiring hospitalization. AI showed an exponential increase throughout the years, with 5282 (62.2%) cases in 2015 to 2020. We identified 56 compounds associated with substantial disproportionality: glucocorticoids (N = 1971), monoclonal antibodies (N = 1644, of which N = 1330 were associated with immune checkpoint inhibitors-ICIs), hormone therapy (N = 291), anti-infectives (N = 252), drugs for hypercortisolism or adrenocortical cancer diagnosis/treatment (N = 169), and protein kinase inhibitors (N = 138). Cases of AI by glucocorticoids were stable in each 5-year period (22%-27%), whereas those by monoclonal antibodies, largely ICIs, peaked from 13% in 2010 to 2015 to 33% in 2015 to 2020. Conclusion: We provide a comprehensive insight into the evolution of drug-induced AI, highlighting the heterogeneous spectrum of culprit drug classes and the emerging increased reporting of ICIs. We claim for the urgent identification of predictive factors for drug-induced AI, and the establishment of screening and educational protocols for patients and caregivers

Adrenal Insufficiency with Anticancer Tyrosine Kinase Inhibitors Targeting Vascular Endothelial Growth Factor Receptor: Analysis of the FDA Adverse Event Reporting System

Background: We described clinical features of adrenal insufficiency (AI) reported with tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factor receptor (VEGFR) in the Food and Drug Administration Adverse Event Reporting System (FAERS). Methods: Reports of AI recorded in FAERS (January 2004–March 2022) were identified through the high-level term “adrenal cortical hypofunctions”. Demographic and clinical features were inspected, and disproportionality signals were detected through the Reporting Odds Ratio (ROR) and Information Component (IC) with relevant 95% confidence/credibility interval (CI), using different comparators and adjusting the ROR for co-reported corticosteroids and immune checkpoint inhibitors (ICIs). Results: Out of 147,153 reports with VEGFR-TKIs, 314 cases of AI were retained, mostly of which were serious (97.1%; hospitalization recorded in 44.9%). In a combination regimen with ICIs (43% of cases), VEGFR-TKIs were discontinued in 52.2% of the cases (26% as monotherapy). The median time to onset was 72 days (IQR = 14–201; calculated for 189 cases). A robust disproportionality signal emerged, also in comparison with other anticancer drugs (ROR = 2.71, 95%CI = 2.42–3.04; IC = 0.25, 95%CI = 0.07–0.39). Cabozantinib, sunitinib and axitinib generated robust disproportionality even after ROR adjustment. Conclusions: We call pharmacologists, internists, oncologists and endocrinologists to raise awareness of serious AI with VEGFR-TKIs, and to develop dedicated guidelines, especially for combination regimens with immunotherapy