Mottness collapse and statistical quantum criticality

We forward here the case that the anomalous electron states found in cuprate superconductors and related systems are rooted in a deeply non-classical fermion sign structure. The collapse of Mottness as advocated by Phillips and supported by recent DCA results on the Hubbard model is setting the necessary microscopic conditions. The crucial insight is due to Weng who demonstrated that in the presence of Mottness the fundamental workings of quantum statistics changes and we will elaborate on the effects of this Weng statistics with an emphasis on characterizing these further using numerical methods. The pseudogap physics of the underdoped regime appears as a consequence of the altered statistics and the profound question is how to connect this by a continuous quantum phase transition to the overdoped regime ruled by normal Fermi-Dirac statistics. Proof of principle follows from Ceperley's constrained path integral formalism where states can be explicitly constructed showing a merger of Fermi-Dirac sign structure and scale invariance of the quantum dynamics.Comment: 27 pages, 4 figures, submitted to theme issue of Phil. Trans. R. Soc.

Long tunneling contact as a probe of fractional quantum Hall neutral edge modes

We study the tunneling current between edge states of quantum Hall liquids across a single long contact region, and predict a resonance at a bias voltage set by the scale of the edge velocity. For typical devices and edge velocities associated with charged modes, this resonance occurs outside the physically accessible bias domain. However, for edge states that are expected to support neutral modes, such as the $\nu={2/3}$, and $\nu={5/2}$ Pfaffian and anti-Pfaffian states, the neutral velocity can be orders of magnitude smaller than the charged mode and if so the resonance would be accessible. Therefore, such long tunneling contacts can resolve the presence of neutral edge modes in certain quantum Hall liquids.Comment: 5+ pages, 2 figures; v2 expanded versio

Effect of inter-edge Coulomb interactions on transport through a point contact in a \nu = 5/2 quantum Hall state

We study transport across a point contact separating two line junctions in a \nu = 5/2 quantum Hall system. We analyze the effect of inter-edge Coulomb interactions between the chiral bosonic edge modes of the half-filled Landau level (assuming a Pfaffian wave function for the half-filled state) and of the two fully filled Landau levels. In the presence of inter-edge Coulomb interactions between all the six edges participating in the line junction, the stable fixed point corresponds to a point contact which is neither fully opaque nor fully transparent. Remarkably, this fixed point represents a situation where the half-filled level is fully transmitting, while the two filled levels are completely backscattered; hence the fixed point Hall conductance is given by G_H = {1/2} e^2/h. We predict the non-universal temperature power laws by which the system approaches the stable fixed point from the two unstable fixed points corresponding to the fully connected case (G_H = {5/2} e^2/h) and the fully disconnected case (G_H = 0).Comment: 6 pages, 3 figures; made several changes -- this is the published versio

Inequivalent classes of interference experiments with non-abelian anyons

We present a theoretical analysis of inequivalent classes of interference experiments with non-abelian anyons using an idealized Mach-Zender type interferometer. Because of the non-abelian nature of the braid group action one has to distinguish the different possibilities in which the experiment can be repeated, which lead to different interference patterns. We show that each setup will, after repeated measurement, lead to a situation where the two-particle (or multi-particle) state gets locked into an eigenstate of some well defined operator. Also the probability to end up in such an eigenstate is calculated. Some representative examples are worked out in detail

Observing the origin of superconductivity in quantum critical metals

Despite intense efforts during the last 25 years, the physics of unconventional superconductors, including the cuprates with a very high transition temperature, is still a controversial subject. It is believed that superconductivity in many of these strongly correlated metallic systems originates in the physics of quantum phase transitions, but quite diverse perspectives have emerged on the fundamentals of the electron-pairing physics, ranging from Hertz style critical spin fluctuation glue to the holographic superconductivity of string theory. Here we demonstrate that the gross energy scaling differences that are behind these various pairing mechanisms are directly encoded in the frequency and temperature dependence of the dynamical pair susceptibility. This quantity can be measured directly via the second order Josephson effect and it should be possible employing modern experimental techniques to build a `pairing telescope' that gives a direct view on the origin of quantum critical superconductivity.Comment: 19 pages, 9 figures; minor changes in the experimental part; added a new appendix section calculating the pair susceptibility of marginal Fermi liqui

Long-Term Halo Follow-Up Confirms Less Invasive Treatment of Low-Grade Cartilaginous Tumors with Radiofrequency Ablation to Be Safe and Effective

Background: Radiofrequency ablation (RFA) is a minimally invasive alternative in the treatment of bone tumors. Long-term follow-up has not been described in current literature. Detailed analysis of mid- and long-term follow-up after RFA treatment for a cohort of patients with low-grade cartilaginous tumors (atypical cartilaginous tumors and enchondroma) was performed. The results, complications, and development of halo dimensions over time are presented. Methods: Data of all patients with an RFA procedure for an ACT between 2007-2018 were included. Ablation area is visible on baseline MRI, 3 months post-procedure, and is called halo. Volume was measured on MR images and compared to different follow-up moments to determine the effect of time on halo volume. Follow-up was carried out 3 months and 1, 2, 5, and 7 years after the procedure. Occurrence of complications and recurrences were assessed. Results: Of the 137 patients included, 82 were analyzed. Mean follow-up time was 43.6 months. Ablation was complete in 73 cases (89.0%). One late complication occurred, while no recurrences were seen. Halo dimensions of height, width, and depth decreased with a similar rate, 21.5% on average in the first year. Subsequently, this decrease in halo size continues gradually during follow-up, indicating bone revitalization. Conclusion: RFA is a safe and effective treatment in low-grade cartilaginous tumors with an initial success rate of 89.0%. Extended follow-up shows no local recurrences and gradual substitution of the halo with normal bone

Can FDG-PET/CT replace blind bone marrow biopsy of the posterior iliac crest in Ewing sarcoma?

OBJECTIVE: To determine and compare the value of (18)F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) to blind bone marrow biopsy (BMB) of the posterior iliac crest in detecting metastatic bone marrow involvement in newly diagnosed Ewing sarcoma. MATERIALS AND METHODS: This retrospective study included 20 patients with newly diagnosed Ewing sarcoma who underwent pretreatment FDG-PET/CT and a total of 38 blind BMBs (two unilateral and 18 bilateral) of the posterior iliac crest. FDG-PET/CT scans were evaluated for bone marrow involvement, both in the posterior iliac crest and other sites, and compared to blind BMB results. RESULTS: FDG-PET/CT was positive for bone marrow involvement in 7/38 posterior iliac crests, whereas BMB was positive in 5/38 posterior iliac crests. FDG-PET/CT and BMB results in the posterior iliac crest agreed in 36/38 cases (94.7%, 95% confidence interval [CI]: 82.7-98.5%). On a patient level, FDG-PET/CT was positive for bone marrow involvement in 4/20 patients, whereas BMB of the posterior iliac crest was positive in 3/20 patients. On a patient level, FDG-PET/CT and BMB results agreed in 19/20 patients (95.0%, 95% CI: 76.4-99.1%). The only discrepancies between FDG-PET/CT and BMB were observed in two BMBs of one patient. Both BMBs in this patient were negative, whereas FDG-PET/CT indicated bilateral posterior iliac crest involvement and also extensive bone marrow involvement elsewhere. CONCLUSIONS: FDG-PET/CT appears to be a valuable method for metastatic bone marrow assessment in newly diagnosed Ewing sarcoma. The routine use of blind BMB of the posterior iliac crest should be reconsidered when FDG-PET/CT is available

Children's spatial analysis of simple and complex Hierarchical Patterns in a Drawing Task

BACKGROUND: Primary tumor volume is as an important and independent prognostic factor in Ewing sarcoma. However, the observer variability of magnetic resonance imaging (MRI)-based primary tumor volume measurements in newly diagnosed Ewing sarcoma has never been investigated. Furthermore, it is unclear how MRI-based volume measurements compare to (18)F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)-based volume measurements. This study aimed to determine the observer variability of simplified MRI-based primary tumor volume measurements in newly diagnosed treatment-naive Ewing sarcoma and to compare them to the actual primary tumor volume at MRI and the FDG-PET-based metabolically active tumor volume (MATV). MATERIAL AND METHODS: Twenty-nine newly diagnosed Ewing sarcoma patients with pretreatment MRI (of whom 11 also underwent FDG-PET) were included. Both exact and dichotomized (according to the proposed threshold of 200 mL) primary tumor volume measurements were analyzed. RESULTS: Mean inter- and intraobserver differences of MRI-based simplified tumor volume ± limits of agreement varied between 15-42 ± 155-204 mL and between 9-16 ± 64-250 mL, respectively. Inter- and intraobserver agreements of dichotomized MRI-based simplified tumor volume measurements was very good (κ = 0.827-1.000). Mean difference between simplified and actual tumor volumes at MRI ± limits of agreement was 60 ± 381 mL. Agreement between dichotomized simplified and actual tumor volumes at MRI was very good (κ = 0.839). Mean difference between MRI-based simplified tumor volume and MATV ± limits of agreement was 181 ± 549 mL and almost significantly different (p = .0581). Agreement between dichotomized MRI-based simplified tumor volume and MATV was moderate (κ = 0.560). CONCLUSIONS: Exact MRI-based simplified primary tumor volume measurements in Ewing sarcoma suffer from considerable observer variability, but observer agreement of dichotomized measurements (≤200 mL vs. >200 mL) is very good and generally matches MRI-based actual volume measurements. MRI-based primary tumor volume measurements poorly-moderately agree with and tend to be lower than the MATV