Imaging spontaneous currents in superconducting arrays of pi-junctions

Superconductors separated by a thin tunneling barrier exhibit the Josephson effect that allows charge transport at zero voltage, typically with no phase shift between the superconductors in the lowest energy state. Recently, Josephson junctions with ground state phase shifts of pi proposed by theory three decades ago have been demonstrated. In superconducting loops, pi-junctions cause spontaneous circulation of persistent currents in zero magnetic field, analogous to spin-1/2 systems. Here we image the spontaneous zero-field currents in superconducting networks of temperature-controlled pi-junctions with weakly ferromagnetic barriers using a scanning SQUID microscope. We find an onset of spontaneous supercurrents at the 0-pi transition temperature of the junctions Tpi = 3 K. We image the currents in non-uniformly frustrated arrays consisting of cells with even and odd numbers of pi-junctions. Such arrays are attractive model systems for studying the exotic phases of the 2D XY-model and achieving scalable adiabatic quantum computers.Comment: Pre-referee version. Accepted to Nature Physic

Height and timing of growth spurt during puberty in young people living with vertically acquired HIV in Europe and Thailand.

OBJECTIVE: The aim of this study was to describe growth during puberty in young people with vertically acquired HIV. DESIGN: Pooled data from 12 paediatric HIV cohorts in Europe and Thailand. METHODS: One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1-10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters. RESULTS: At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and -1.2 (IQR: -2.3 to -0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20-0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21-1.78) years later in those starting with HAZ less than -3 compared with HAZ at least -1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than -1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least -1, there was no association with age. Girls and boys who initiated ART with HAZ at least -1 maintained a similar height to the WHO reference mean. CONCLUSION: Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least -1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age

Height and timing of growth spurt during puberty in young people living with vertically acquired HIV in Europe and Thailand

Objective: The aim of this study was to describe growth during puberty in young people with vertically acquired HIV. Design: Pooled data from 12 paediatric HIV cohorts in Europe and Thailand. Methods: One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1-10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters. Results: At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and -1.2 (IQR: -2.3 to -0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20-0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21-1.78) years later in those starting with HAZ less than -3 compared with HAZ at least -1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than -1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least -1, there was no association with age. Girls and boys who initiated ART with HAZ at least -1 maintained a similar height to the WHO reference mean. Conclusion: Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least -1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age

Inflammatory epidermolysis bullosa acquisita with coexistent IgA antibodies to plectin

We present a case of inflammatory epidermolysis bullosa acquisita (EBA) with IgA antibodies to plectin. Analysis of lesional skin biopsies by electron microscopy revealed the split level to be in the sublamina densa zone, corresponding to the diagnosis of EBA. Direct immunofluorescence of perilesional skin demonstrated u-serrated depositions of IgG and IgA that under immunoelectron microcopy were shown to be located in the sublamina densa. In contrast, indirect immunofluorescence on salt-split skin revealed circulating IgA antibodies that stained the roof rather than the floor of the blister. Immunoblotting showed these serum antibodies to be directed to the cytoplasmic hemidesmosomal antigen plectin. The antiplectin specificity of these antibodies was confirmed by 'knockout' immunofluorescence analysis; the serum IgA did not bind to skin sections of a patient with plectin-deficient epidermolysis bullosa. To our knowledge, this case demonstrates for the first time the existence of IgA antibodies against plectin

Novel radiopaque ultrahigh molecular weight polyethylene sublaminar wires in a growth-guidance system for the treatment of early-onset scoliosis:feasibility in a large animal study

\u3cp\u3eSTUDY DESIGN. In vivo analysis in an ovine model. OBJECTIVE. To evaluate the feasibility of radiopaque ultrahigh molecular weight polyethylene (UHMWPE) sublaminar wires in a growth-guidance spinal system by assessing stability, biocompatibility, and growth potential. SUMMARY OF BACKGROUND DATA. Several growth-guidance systems have been developed for the treatment of early-onset scoliosis. The use of gliding pedicle screws and metal sublaminar wires during these procedures can cause metal-on-metal debris formation and neurological deficits. Novel radiopaque UHMWPE wires are introduced to safely facilitate longitudinal growth and provide stability in a growth-guidance system for early-onset scoliosis. METHODS. Twelve immature sheep received posterior segmental spinal instrumentation; pedicle screws were inserted at L5 and radiopaque UHMWPE (bismuth trioxide) wires were passed sublaminarly at each level between L3 and T12 and fixed to dual cobalt-chromium rods. Four age-matched animals that were not operated were evaluated to serve as a control group. Radiographs were obtained to measure growth of the instrumented segment. After 24 weeks, the animals were killed and the spines were harvested for histological evaluation and high-resolution peripheral quantitative computed tomographic analysis. RESULTS. No neurological deficits occurred and all instrumentation remained stable. One animal died from an unknown cause. Substantial growth occurred in the instrumented segments (L5-T11) in the intervention group (27 ± 2 mm), which was not significantly different to the control group, (30 ± 4 mm, P = 0.42). High-resolution peripheral quantitative computed tomographic analysis clearly showed safe routing and fixation of the UHMWPE wires and instrumentation. Despite the noted growth, ectopic bone formation with the formation of bony bridges was observed in all animals. Histology revealed no evidence of chronic inflammation or wear debris. CONCLUSION. This study shows the first results of radiopaque UHMWPE sublaminar wires as part of a growth-guidance spinal system. UHMWPE sublaminar wires facilitated near-normal longitudinal spinal growth. All instrumentation remained stable throughout follow-up; no wire breakage or loosening occurred and no adverse local-tissue response to these wires was observed. Level of Evidence: N/A.\u3c/p\u3

Distal radius plate of CFR-PEEK has minimal effect compared to titanium plates on bone parameters in high-resolution peripheral quantitative computed tomography: a pilot study

\u3cp\u3eBACKGROUND: Carbon-fiber-reinforced poly-ether-ether-ketone (CFR-PEEK) has superior radiolucency compared to other orthopedic implant materials, e.g. titanium or stainless steel, thus allowing metal-artifact-free postoperative monitoring by computed tomography (CT). Recently, high-resolution peripheral quantitative CT (HRpQCT) proved to be a promising technique to monitor the recovery of volumetric bone mineral density (vBMD), micro-architecture and biomechanical parameters in stable conservatively treated distal radius fractures. When using HRpQCT to monitor unstable distal radius fractures that require volar distal radius plating for fixation, radiolucent CFR-PEEK plates may be a better alternative to currently used titanium plates to allow for reliable assessment. In this pilot study, we assessed the effect of a volar distal radius plate made from CFR-PEEK on bone parameters obtained from HRpQCT in comparison to two titanium plates.\u3c/p\u3e\u3cp\u3eMETHODS: Plates were instrumented in separate cadaveric human fore-arms (n = 3). After instrumentation and after removal of the plates duplicate HRpQCT scans were made of the region covered by the plate. HRpQCT images were visually checked for artifacts. vBMD, micro-architectural and biomechanical parameters were calculated, and compared between the uninstrumented and instrumented radii.\u3c/p\u3e\u3cp\u3eRESULTS: No visible image artifacts were observed in the CFR-PEEK plate instrumented radius, and errors in bone parameters ranged from -3.2 to 2.6%. In the radii instrumented with the titanium plates, severe image artifacts were observed and errors in bone parameters ranged between -30.2 and 67.0%.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: We recommend using CFR-PEEK plates in longitudinal in vivo studies that monitor the healing process of unstable distal radius fractures treated operatively by plating or bone graft ingrowth.\u3c/p\u3

Effect of a cast on short-term reproducibility and bone parameters obtained from HR-pQCT measurements at the distal end of the radius

\u3cp\u3eBACKGROUND: High-resolution peripheral quantitative computed tomography (HR-pQCT) is a promising tool to assess the fracture-healing process at the microscale in vivo. Since casts are often used during fracture treatment, they might affect the assessment of bone density, microarchitectural, and biomechanical parameters and the short-term reproducibility of those parameters, e.g., as a result of beam-hardening. The aim of this study was to assess the effect of a plaster-of-Paris and/or fiberglass cast on bone parameters and on the short-term reproducibility of the HR-pQCT measurements of those parameters.\u3c/p\u3e\u3cp\u3eMETHODS: The effects of a cast on HR-pQCT-derived bone parameters were evaluated by comparing HR-pQCT scans of fifteen human cadaveric distal radial specimens from one male and fourteen female donors (median age, eighty-four years [range, sixty-two to ninety years] at the time of death) in three conditions: with a plaster-of-Paris cast, with a fiberglass cast, or without a cast. Short-term reproducibility was assessed using duplicate scans of the distal end of the radius in sixteen healthy volunteers without a fracture (nine men and seven women with a median age of twenty-six years; range, twenty-two to thirty-nine years) while wearing and not wearing a fiberglass cast.\u3c/p\u3e\u3cp\u3eRESULTS: Compared with measurements made with no cast, the plaster-of-Paris cast introduced a systematic error in the bone parameters ranging from -2.6% in trabecular separation to -9.8% in cortical thickness. Bone parameters were affected only marginally by fiberglass, with errors between -0.6% and -1.6% in trabecular separation and cortical thickness, respectively. Short-term reproducibility with a fiberglass cast was similar to that with no cast: approximately 1% for bone density parameters, 4% to 5% for microarchitectural parameters, and 3% to 4% for biomechanical parameters.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: A plaster-of-Paris cast has a considerable effect on HR-pQCT measurements. A fiberglass cast only marginally affects the bone parameters, and the short-term reproducibility of HR-pQCT measurements in patients with a fiberglass cast is comparable with that in patients without a cast. In studies on fracture-healing using HR-pQCT, a fiberglass cast is desirable if immobilization is indicated. The use of a plaster-of-Paris cast should be avoided if possible; however, if not avoidable, corrections after the scan are desirable to adjust for the error introduced in the bone parameters.\u3c/p\u3