Strong Pinning and Plastic Deformations of the Vortex Lattice

We investigate numerically the dynamically generated plastic deformations of a 3D vortex lattice (VL) driven through a disorder potential with isolated, strong pinning centers (point-like or extended along the field direction). We find that the VL exhibits a very peculiar dynamical behavior in the plastic flow regime, in particular, topological excitations consisting of three or four entangled vortices are formed. We determine the critical current density $j_c$ and the activation energy for depinning $U_c$ in the presence of a finite density of strong pinning centers.Comment: 12 pages, TeX type, Postscript figure

Self-organization of vortices in type-II superconductors during magnetic relaxation

We revise the applicability of the theory of self-organized criticality (SOC) to the process of magnetic relaxation in type-II superconductors. The driving parameter of self-organization of vortices is the energy barrier for flux creep and not the current density. The power spectrum of the magnetic noise due to vortex avalanches is calculated and is predicted to vary with time during relaxation.Comment: RevTex, 5 pages, 2 PS figures. Accepted in Phys. Rev.

Dynamics of Flux Creep in Underdoped Single Crystals of Y_1-xPr_xBa_2Cu_3O_7-d

Transport as well as magnetic relaxation properties of the mixed state were studied on strongly underdoped Y_1-xPr_xBa_2Cu_3O_7-d crystals. We observed two correlated phenomena - a coupling transition and a transition to quantum creep. The distribution of transport current below the coupling transition is highly nonuniform, which facilitates quantum creep. We speculate that in the mixed state below the coupling transition, where dissipation is nonohmic, the current distribution may be unstable with respect to self-channeling resulting in the formation of very thin current-carrying layers.Comment: 11 pages, 9 figures, Submitted to Phys. Rev.

Plasticity and memory effects in the vortex solid phase of twinned YBa2Cu3O7 single crystals

We report on marked memory effects in the vortex system of twinned YBa2Cu3O7 single crystals observed in ac susceptibility measurements. We show that the vortex system can be trapped in different metastable states with variable degree of order arising in response to different system histories. The pressure exerted by the oscillating ac field assists the vortex system in ordering, locally reducing the critical current density in the penetrated outer zone of the sample. The robustness of the ordered and disordered states together with the spatial profile of the critical current density lead to the observed memory effects

Humanistic and economic impact of moderate to severe plaque psoriasis in Brazil

Introduction Psoriasis is an immune-mediated, chronic, inflammatory disease, which has a substantial humanistic and economic burden. This study aimed to assess the impact of this disease on health-related quality of life (HRQoL), work productivity, and direct and indirect costs from a societal perspective among Brazilian patients. Methods This is a cross-sectional, observational, multicenter study, enrolling patients with moderate to severe plaque psoriasis according to physician evaluation. Data collection was performed from December 2015 to November 2016 through face-to-face interviews using a structured questionnaire and five standardized patient-reported outcomes instruments. Direct costs were estimated by multiplying the amount of resources used (12-month recall period) by the corresponding unit cost. Indirect costs were grouped in two time horizons: annual costs (income reduction and absenteeism) and lifetime costs (demission and early retirement). Results A total of 188 patients with moderate to severe plaque psoriasis were included, with mean age of 48.0 (SD 13.1). “Anxiety and depression” and “pain and discomfort” were the most impaired dimensions, according to the EuroQol Five-Dimension-Three-Level (EQ-5D-3L). The highest effect was found for “symptoms and feelings” [mean (SD) 2.4 (1.7)] Dermatology Life Quality Index (DLQI) subscale. Psoriatic arthritis (PsA) presence and biologic-naïve status were associated with worse HRQoL. Presenteeism was more frequent than absenteeism, according to the Work Productivity and Activity Impairment questionnaire-General Health (WPAI-GH) [17.4% vs. 6.3%], while physical demands and time management were the most affected Work Limitations Questionnaire (WLQ) subscales [means (SD) 23.5 (28.5) and 17.7 (24.9), respectively]. The estimated annual cost per patient was USD 4034. Direct medical costs accounted for 87.7% of this estimate, direct non-medical costs for 2.4%, and indirect costs for 9.9%. Conclusions Results evidenced that moderate to severe plaque psoriasis imposes substantial costs to society. Our data showed that this disease negatively affects both work productivity and HRQoL of Brazilian patients. Subgroups with PsA and biologic-naïve patients presented lower HRQoL, showing the impact of this comorbidity and the relevance of biologics in psoriasis treatment

Pinning-induced transition to disordered vortex phase in layered superconductors

Destruction of the vortex lattice by random point pinning is considered as a mechanism of the ``second peak'' transition observed experimentally in weakly coupled layered high temperature superconductors. The transition field separating the topologically ordered quasilattice from the amorphous vortex configuration is strongly influenced by the layered structure and by the nonlocal nature of the vortex tilt energy due to the magnetic interlayer coupling. We found three different regimes of transition depending on the relative strength of the Josephson and magnetic couplings. The regimes can be distinguished by the dependence of the transition fieldComment: 8 pages, 3 Postscript figures. Accepted to Phys. Rev.B. (regular article

Mixed origin of neovascularization of human endometrial grafts in immunodeficient mouse models

peer reviewedBACKGROUND: In vivo mouse models have been developed to study the physiology of normal and pathologic endometrium. Although angiogenesis is known to play an important role in endometrial physiology and pathology, the origin of neovasculature in xenografts remains controversial. The aim of this study was to assess the origin of the neovasculature of endometrial grafts in different mouse models. METHODS: Human proliferative endometrium (n = 19 women) was grafted s.c. in two immunodeficient mouse strains: nude (n = 8) and severely compromised immunodeficient (SCID; n = 20). Mice were also treated with estradiol, progesterone or levonorgestrel. Fluorescence in-situ hybridization using a centromeric human chromosome X probe, immunohistochemistry (von Willebrand factor and collagen IV) and lectin perfusion were performed to identify the origin of the vessels. RESULTS: More than 90% of vessels within xenografts were of human origin 4 weeks after implantation. Some vessels (9.67 +/- 2.01%) were successively stained by human or mouse specific markers, suggesting the presence of chimeric vessels exhibiting a succession of human and murine portions. No difference in staining was observed between the two strains of mouse or different hormone treatments. Furthermore, erythrocytes were found inside human vessels, confirming their functionality. CONCLUSION: This article shows that human endometrial grafts retain their own vessels, which connect to the murine vasculature coming from the host tissue and become functional

Fish-tail Effect and Irreversibility Field of (Cu,C)Ba2_{2}Ca3_{3}Cu4_{4}Ox_{x}-(LiF)y_{y} superconductor

Addition of (LiF)$_{y<0.15}$, and of proper amount of (AgO)$_{z=0.45-0.8}$ as oxidizing agent, to (Cu,C)Ba$_{2}$Ca$_{3}$Cu$_{4}$O$_{10+d}$ superconductor is useful to control and shift the doping characteristics (hole density and distribution, and level of disorder) into the region where the irreversible properties, i.e. fish-tail effect (FTE) and irreversibility field H$_{irr}$, are improved. Among notable effects are the development of the second magnetization peak with a higher amplitude J$_{c}$, max and the enhancement of H$_{irr}$ at high temperatures, above a certain value T* which depends on both y$_{LiF}$ and z$_{AgO}$. The best results are obtained for the sample with y$_{LiF}$=0.1 and z$_{AgO}$=0.73. This sample preserves its single phase Cu,C-1234 composition. The influence on the FTE and H$_{irr}$ of the interplay between doping characteristics, controlled by LiF and AgO content, is discussed.Comment: 28 pages, accepted to J. Supercon

Vortex phase diagram in BSCCO with damage tracks created by 30 MeV fullerene irradiation

Using 30 MeV C60 fullerene irradiation, we have produced latent tracks of diameter 20 nm and length 200 nm, near the surface of single crystalline BSCCO. A preliminary transmission electron microscopy study shows evidence for a very high density of deposited energy, and the ejection of material from the track core in very thin specimens. The latent tracks reveal themselves to be exceptionally strong pinning centers for vortices in the superconducting mixed state. Both the critical current density and magnetic irreversibility line are significantly enhanced. The irradiated crystals present salient features of the (B,T) phase diagram of vortex matter both of pristine crystals, such as the first order vortex phase transition, and the exponential Bose-glass line characteristic of heavy ion-irradiated crystals. We show that the latter is manifestly independent of the pinning potential.Comment: 10 pages, 13 figure