Equilibrium phases of dipolar lattice bosons in the presence of random diagonal disorder

Ultracold gases offer an unprecedented opportunity to engineer disorder and interactions in a controlled manner. In an effort to understand the interplay between disorder, dipolar interaction and quantum degeneracy, we study two-dimensional hard-core dipolar lattice bosons in the presence of on-site bound disorder. Our results are based on large-scale path-integral quantum Monte Carlo simulations by the Worm algorithm. We study the ground state phase diagram at fixed half-integer filling factor for which the clean system is either a superfluid at lower dipolar interaction strength or a checkerboard solid at larger dipolar interaction strength. We find that, even for weak dipolar interaction, superfluidity is destroyed in favor of a Bose glass at relatively low disorder strength. Interestingly, in the presence of disorder, superfluidity persists for values of dipolar interaction strength for which the clean system is a checkerboard solid. At fixed disorder strength, as the dipolar interaction is increased, superfluidity is destroyed in favor of a Bose glass. As the interaction is further increased, the system eventually develops extended checkerboard patterns in the density distribution. Due to the presence of disorder, though, grain boundaries and defects, responsible for a finite residual compressibility, are present in the density distribution. Finally, we study the robustness of the superfluid phase against thermal fluctuations

Equilibrium Phases of Tilted Dipolar Lattice Bosons

The recent advances in creating nearly degenerate quantum dipolar gases in optical lattices are opening the doors for the exploration of equilibrium physics of quantum systems with anisotropic and long-range dipolar interactions. In this paper we study the zero- and finite-temperature phase diagrams of a system of hard-core dipolar bosons at half-filling, trapped in a two-dimensional optical lattice. The dipoles are aligned parallel to one another and tilted out of the optical lattice plane by means of an external electric field. At zero-temperature, the system is a superfluid at all tilt angles $\theta$ provided that the strength of dipolar interaction is below a critical value $V_c(\theta)$. Upon increasing the interaction strength while keeping $\theta$ fixed, the superfluid phase is destabilized in favor of a checkerboard or a stripe solid depending on the tilt angle. We explore the nature of the phase transition between the two solid phases and find evidence of a micro-emulsion phase, following the Spivak-Kivelson scenario, separating these two solid phases. Additionally, we study the stability of these quantum phases against thermal fluctuations and find that the stripe solid is the most robust, making it the best candidate for experimental observation.Comment: 7 pages, 6 figure

Quantum phases of hard-core dipolar bosons in coupled one-dimensional optical lattices

Hard-core dipolar bosons trapped in a parallel stack of N ≥ 2 one-dimensional optical lattices (tubes) can develop several phases made of composites of particles from different tubes: superfluids, supercounterfluids, and insulators as well as mixtures of those. Bosonization analysis shows that these phases are thresholdless with respect to the dipolar interaction, with the key “control knob” being filling factors in each tube, provided the intertube tunneling is suppressed. The effective ab initio quantum Monte Carlo algorithm capturing these phases is introduced and some results are presented.National Science Foundation (U.S.) (Grant CNS-0855217)National Science Foundation (U.S.) (Grant CNS-0958379)National Science Foundation (U.S.) (Grant ACI-1126113

Chemotherapy-Response Monitoring of Breast Cancer Patients Using Quantitative Ultrasound-Based Intra-Tumour Heterogeneities

© 2017 The Author(s). Anti-cancer therapies including chemotherapy aim to induce tumour cell death. Cell death introduces alterations in cell morphology and tissue micro-structures that cause measurable changes in tissue echogenicity. This study investigated the effectiveness of quantitative ultrasound (QUS) parametric imaging to characterize intra-tumour heterogeneity and monitor the pathological response of breast cancer to chemotherapy in a large cohort of patients (n = 100). Results demonstrated that QUS imaging can non-invasively monitor pathological response and outcome of breast cancer patients to chemotherapy early following treatment initiation. Specifically, QUS biomarkers quantifying spatial heterogeneities in size, concentration and spacing of acoustic scatterers could predict treatment responses of patients with cross-validated accuracies of 82 ± 0.7%, 86 ± 0.7% and 85 ± 0.9% and areas under the receiver operating characteristic (ROC) curve of 0.75 ± 0.1, 0.80 ± 0.1 and 0.89 ± 0.1 at 1, 4 and 8 weeks after the start of treatment, respectively. The patients classified as responders and non-responders using QUS biomarkers demonstrated significantly different survivals, in good agreement with clinical and pathological endpoints. The results form a basis for using early predictive information on survival-linked patient response to facilitate adapting standard anti-cancer treatments on an individual patient basis

Breast-Lesion Characterization using Textural Features of Quantitative Ultrasound Parametric Maps

© 2017 The Author(s). This study evaluated, for the first time, the efficacy of quantitative ultrasound (QUS) spectral parametric maps in conjunction with texture-analysis techniques to differentiate non-invasively benign versus malignant breast lesions. Ultrasound B-mode images and radiofrequency data were acquired from 78 patients with suspicious breast lesions. QUS spectral-analysis techniques were performed on radiofrequency data to generate parametric maps of mid-band fit, spectral slope, spectral intercept, spacing among scatterers, average scatterer diameter, and average acoustic concentration. Texture-analysis techniques were applied to determine imaging biomarkers consisting of mean, contrast, correlation, energy and homogeneity features of parametric maps. These biomarkers were utilized to classify benign versus malignant lesions with leave-one-patient-out cross-validation. Results were compared to histopathology findings from biopsy specimens and radiology reports on MR images to evaluate the accuracy of technique. Among the biomarkers investigated, one mean-value parameter and 14 textural features demonstrated statistically significant differences (p < 0.05) between the two lesion types. A hybrid biomarker developed using a stepwise feature selection method could classify the legions with a sensitivity of 96%, a specificity of 84%, and an AUC of 0.97. Findings from this study pave the way towards adapting novel QUS-based frameworks for breast cancer screening and rapid diagnosis in clinic

The relative frequency, clinical and laboratory findings of adult glomerulonephritidies in Tehran

Background: Renal diseases information is population-based and has great geographic variability. Due to the lack of national renal data registry system, there is no information on the prevalence rate, and clinical and laboratory features of various glomerulonephritidies (GNs) in Iran. Methods: In a retrospective cross sectional study, we analyzed 462 adult renal biopsies in Hashemi Nejad hospital, Tehran, Iran. We determined the prevalence rate and the frequency of different clinical and laboratory findings in patients with different GNs. We also compared our results with the reports from other countries. Results: There were 267(57.8) males and 195(42.2) females. The mean age (± SD) was 33.6 ± 15.7 (range, 13-75) years old. After exclusion of 55 biopsies with pathologies other than GNs and in the remaining 407 biopsies, membranous glomerulopathy (MGN) was the most common GN (23.6), followed by IgAN (13.5), membranoproliferative GN (11.5), systemic lupus nephritis (10.6), focal segmental glomerulosclerosis (10.3), and minimal change disease (9.8). These 6 GNs comprised the majority (79.4) of all GNs. Conclusion: MGN is the most common form of GN, followed by IgAN, MPGN, SLE-GN, FSGS and MCD in adult patients in our study. The multi-center studies with a larger sample size are needed for more comprehensive data in Iranian population

Multiworm algorithm quantum Monte Carlo

We review the path-integral quantum Monte Carlo method and discuss its implementation by multiworm algorithms. We analyze in details the features of the algorithms, and focus our attention on the computation of the $N$-body density matrix to study N-body correlations. Finally, we demonstrate the validity of the algorithms on a system of dipolar bosons trapped in a stack of $N$ one-dimensional layers in the case of zero and finite inter-layer hopping.Comment: 20 pages, 10 figure

Monitoring Breast Cancer Response to Neoadjuvant Chemotherapy Using Ultrasound Strain Elastography

© 2019 The Authors Strain elastography was used to monitor response to neoadjuvant chemotherapy (NAC) in 92 patients with biopsy-proven, locally advanced breast cancer. Strain elastography data were collected before, during, and after NAC. Relative changes in tumor strain ratio (SR) were calculated over time, and responder status was classified according to tumor size changes. Statistical analyses determined the significance of changes in SR over time and between response groups. Machine learning techniques, such as a naïve Bayes classifier, were used to evaluate the performance of the SR as a marker for Miller-Payne pathological endpoints. With pathological complete response (pCR) as an endpoint, a significant difference (P < .01) in the SR was observed between response groups as early as 2 weeks into NAC. Naïve Bayes classifiers predicted pCR with a sensitivity of 84%, specificity of 85%, and area under the curve of 81% at the preoperative scan. This study demonstrates that strain elastography may be predictive of NAC response in locally advanced breast cancer as early as 2 weeks into treatment, with high sensitivity and specificity, granting it the potential to be used for active monitoring of tumor response to chemotherapy