Flat-band localization and interaction-induced delocalization of photons

Advances in quantum engineering have enabled the design, measurement, and precise control of synthetic condensed matter systems. The platform of superconducting circuits offers two particular capabilities: flexible connectivity of circuit elements that enables a variety of lattice geometries, and circuit nonlinearity that provides access to strongly interacting physics. Separately, these features have allowed for the creation of curved-space lattices and the realization of strongly correlated phases and dynamics in one-dimensional chains and square lattices. Missing in this suite of simulations is the simultaneous integration of interacting particles into lattices with unique band dispersions, such as dispersionless flat bands. An ideal building block for flat-band physics is the Aharonov-Bohm cage: a single plaquette of a lattice whose band structure consists entirely of flat bands. Here, we experimentally construct an Aharonov-Bohm cage and observe the localization of a single photon, the hallmark of all-bands-flat physics. Upon placing an interaction-bound photon pair into the cage, we see a delocalized walk indicating an escape from Aharonov-Bohm caging. We further find that a variation of caging persists for two particles initialized on opposite sites of the cage. These results mark the first experimental observation of a quantum walk that becomes delocalized due to interactions and establish superconducting circuits for studies of flat-band-lattice dynamics with strong interactions.Comment: 8 + 9 pages, 4 + 12 figures, 0 + 2 tables; modified title, added a supplementary figure, and modified the definition used for tunneling tim

Barriers and Challenges to Treatment Alternatives for Early-Stage Cervical Cancer in Lower-Resource Settings

Cervical cancer is one of the most common cancers among women worldwide, and approximately 85% of new diagnoses occur in less-developed regions of the world. Global efforts in cervical cancer to date have focused on primary and secondary prevention strategies of human papillomavirus vaccination and cervical cancer screening. Cervical cancer screening is effective to reduce the incidence of cervical cancer and can result in diagnosis at earlier stages, but it will take time to realize its full impact. With expansion of screening programs, there is now a greater imperative to increase access to treatment for women who have cervical cancer, particularly in earlier stages of disease, when it is still curable. Resources for multimodality treatment can be limited—or even absent—in many less-developed regions of the world and may be associated with geographic, social, and financial barriers for the patient. However, there is evidence that, in many cases, less-invasive and less–resource-intensive treatment options are still effective. To this end, the National Comprehensive Cancer Network and American Society of Clinical Oncology have published guideline adaptations for specific resource constraints, and research about more conservative approaches to the treatment of cervical cancer continues. This review focuses on potential barriers and challenges to provision of safe and effective treatment of early-stage cervical cancer in lower-resource settings, and it suggests future directions for expansion of access to cervical cancer treatment around the world

Immunohistochemical and Biochemical Characterization of Mucin in Pseudomyxoma Peritonei: A Case Study

We previously reported the presence of MUC2, MUC5AC and, for the first time, MUC5B in a 58-year-old male with pseudomyxoma peritonei (PMP). This is a report on the biochemical and immunohistochemical characterization of mucin in a 50-year-old female with the same rare illness. A right oophorectomy and appendicectomy and a resection of the involved omentum were performed. Approximately a litre of crude material in the sol and gel phases was obtained from the patient during laparotomy. This was briefly homogenized in 6 M guanidinium hydrochloride and proteolytic inhibitors and purified by density gradient centrifugation in caesium chloride. At laparotomy it was noted that the patient had appendiceal and ovarian masses as well as extensive mucinous deposits in the omentum and peritoneum. A mucinous adenocarcinoma of the appendix and ovary was confirmed on histology. The cells expressed both sulphated and non-sulphated acidic mucins. The presence of MUC2, MUC5AC, MUC5B and a-1-acid glycoprotein was shown by Western blotting and MUC4 by immunohistochemical staining. MUC1 and MUC6 were not detectable in the tissue. The study confirms that MUC2, MUC5AC and MUC5B are produced in the mucus of patients with PMP. The expression of MUC4 in this disease has not been previously reported

Certified Reduced Basis Methods and Output Bounds for the Harmonic Maxwell's Equations

We propose certified reduced basis methods for the efficient and reliable evaluation of a general output that is implicitly connected to a given parameterized input through the harmonic Maxwell's equations. The truth approximation and the development of the reduced basis through a greedy approach is based on a discontinuous Galerkin approximation of the linear partial differential equation. The formulation allows the use of different approximation spaces for solving the primal and the dual truth approximation problems to respect the characteristics of both problem types, leading to an overall reduction in the off-line computational effort. The main features of the method are the following: (i) rapid convergence on the entire representative set of parameters, (ii) rigorous a posteriori error estimators for the output, and (iii) a parameter independent off-line phase and a computationally very efficient on-line phase to enable the rapid solution of many-query problems arising in control, optimization, and design. The versatility and performance of this approach is shown through a numerical experiment, illustrating the modeling of material variations and problems with resonant behavior

Improved successive constraint method based a posteriori error estimate for reduced basis approximation of 2D Maxwell's problem

In a posteriori error analysis of reduced basis approximations to affinely parametrized partial differential equations, the construction of lower bounds for the coercivity and inf-sup stability constants is essential. In [Huynh et al., C. R. Acad. Sci. Paris Ser. I Math. 345 ( 2007) 473-478], the authors presented an efficient method, compatible with an off-line/on-line strategy, where the online computation is reduced to minimizing a linear functional under a few linear constraints. These constraints depend on nested sets of parameters obtained iteratively using a greedy algorithm. We improve here this method so that it becomes more efficient and robust due to two related properties: (i) the lower bound is obtained by a monotonic process with respect to the size of the nested sets; (ii) less eigen-problems need to be solved. This improved evaluation of the inf-sup constant is then used to consider a reduced basis approximation of a parameter dependent electromagnetic cavity problem both for the greedy construction of the elements of the basis and the subsequent validation of the reduced basis approximation. The problem we consider has resonance features for some choices of the parameters that are well captured by the methodology

RNA elements directing in vivo assembly of the 7SK/MePCE/Larp7 transcriptional regulatory snRNP

Through controlling the nuclear level of active positive transcription elongation factor b (P-TEFb), the 7SK small nuclear RNA (snRNA) functions as a key regulator of RNA polymerase II transcription. Together with hexamethylene bisacetamide-inducible proteins 1/2 (HEXIM1/2), the 7SK snRNA sequesters P-TEFb into transcriptionally inactive ribonucleoprotein (RNP). In response to transcriptional stimulation, the 7SK/HEXIM/P-TEFb RNP releases P-TEFb to promote polymerase II-mediated messenger RNA synthesis. Besides transiently associating with HEXIM1/2 and P-TEFb, the 7SK snRNA stably interacts with the La-related protein 7 (Larp7) and the methylphosphate capping enzyme (MePCE). In this study, we used in vivo RNA-protein interaction assays to determine the sequence and structural elements of human 7SK snRNA directing assembly of the 7SK/MePCE/Larp7 core snRNP. MePCE interacts with the short 5'-terminal G1-U4/U106-G111 helix-tail motif and Larp7 binds to the 3'-terminal hairpin and the following U-rich tail of 7SK. The overall RNA structure and some particular nucleotides provide the information for specific binding of MePCE and Larp7. We also demonstrate that binding of Larp7 to 7SK is a prerequisite for in vivo recruitment of P-TEFb, indicating that besides providing stability for 7SK, Larp7 directly participates in P-TEFb regulation. Our results provide further explanation for the frequently observed link between Larp7 mutations and cancer development

Productivity of three sugarcane cultivars under dry and drip irrigated management

O objetivo neste trabalho foi estudar o efeito da tecnologia de irrigação por gotejamento, em cultivares de cana-de-açúcar, em dois ciclos de produção (cana-planta e cana-soca). O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições, constituídos pela combinação de três cultivares de cana-de-açúcar: RB867515; RB855536 e SP80-3280, e dois manejos da cultura: sistema de irrigação por gotejamento subterrâneo e sistema de sequeiro, totalizando seis tratamentos. O primeiro ciclo teve duração de 336 dias, ocorrendo precipitação de 1.480 mm. O volume de água disponibilizado pelo sistema de irrigação por gotejamento foi de 400 mm, totalizando 1.880 mm. O segundo ciclo teve duração de 365 dias, cujo volume de água por meio de precipitação foi de 1.394 mm; somados aos 320 mm fornecidos pelo sistema de irrigação, totalizaram 1.714 mm. Ocorreu interação entre manejo e cultivar para as variáveis: produtividade de colmos (TCH) e produtividade de açúcar (TPH) em que a maior diferença foi observada para a cultivar SP80-3280. As cultivares apresentaram respostas diferenciadas na eficiência de utilização da água. No manejo irrigado por gotejamento houve elevação de 24% na produtividade de colmos e de 23% na produtividade de açúcar, em relação ao manejo de sequeiro.This study aimed to evaluate the effect of drip irrigation technology in different sugarcane varieties in two crop cycles (plant cane and ratoon). The experimental design was in completly randomized blocks, in split-plot with four replications, constituted by three sugarcane genotypes: RB867515; RB855536 and SP80-3280 and two crop management: drip irrigation system and rainfed system, totalizing six treatments. The first cycle lasted for 336 days, with rainfall of 1,480 mm. The volume of water provided by the system of drip irrigation was 400 mm, totaling 1,880 mm. The second cycle lasted for 365 days, the volume of water through rainfall was 1,394 mm, added to 320 mm provided by the system of irrigation, totaled 1,714 mm. Interaction between management and cultivars was found significant for the variables: productivity of stalks (TCH) and sugar yield (TPH), in which the largest difference was observed for cultivar SP80-3280. There was significant response to drip irrigation, on average the increase of production of stalks and sugar was 24 and 23%, respectively

Certified reduced basis method for electromagnetic scattering and radar cross section estimation

We study nontrivial applications of the reduced basis method (RBM) for electromagnetic applications with an emphasis on scattering and the estimation of radar cross section (RCS). The method and several extensions are explained with two examples with different characteristics. Parameters that are allowed to vary within the model include frequency, incident angle and measurement angle as well as the geometry of the scatterers. With appropriate applications of the empirical interpolation method (EIM), transformation of the domain, configuration of perfectly matched layer, exponential convergence of the reduced basis solution over the entire parameter domain is achieved. Moreover, we demonstrate that this approach allows for the effective capture of the critical behavior, in this case through shapes that minimize scattering. This further highlights the robustness and quality of the greedy approximation and the reduced basis method approach. (C) 2012 Elsevier B.V. All rights reserved