Accurately computing the electronic properties of a quantum ring.

A promising approach to study condensed-matter systems is to simulate them on an engineered quantum platform1-4. However, the accuracy needed to outperform classical methods has not been achieved so far. Here, using 18 superconducting qubits, we provide an experimental blueprint for an accurate condensed-matter simulator and demonstrate how to investigate fundamental electronic properties. We benchmark the underlying method by reconstructing the single-particle band structure of a one-dimensional wire. We demonstrate nearly complete mitigation of decoherence and readout errors, and measure the energy eigenvalues of this wire with an error of approximately 0.01 rad, whereas typical energy scales are of the order of 1 rad. Insight into the fidelity of this algorithm is gained by highlighting the robust properties of a Fourier transform, including the ability to resolve eigenenergies with a statistical uncertainty of 10-4 rad. We also synthesize magnetic flux and disordered local potentials, which are two key tenets of a condensed-matter system. When sweeping the magnetic flux we observe avoided level crossings in the spectrum, providing a detailed fingerprint of the spatial distribution of local disorder. By combining these methods we reconstruct electronic properties of the eigenstates, observing persistent currents and a strong suppression of conductance with added disorder. Our work describes an accurate method for quantum simulation5,6 and paves the way to study new quantum materials with superconducting qubits.

Rate heterogeneity across Squamata, misleading ancestral state reconstruction and the importance of proper null model specification.

The binary-state speciation and extinction (BiSSE) model has been used in many instances to identify state-dependent diversification and reconstruct ancestral states. However, recent studies have shown that the standard procedure of comparing the fit of the BiSSE model to constant-rate birth-death models often inappropriately favours the BiSSE model when diversification rates vary in a state-independent fashion. The newly developed HiSSE model enables researchers to identify state-dependent diversification rates while accounting for state-independent diversification at the same time. The HiSSE model also allows researchers to test state-dependent models against appropriate state-independent null models that have the same number of parameters as the state-dependent models being tested. We reanalyse two data sets that originally used BiSSE to reconstruct ancestral states within squamate reptiles and reached surprising conclusions regarding the evolution of toepads within Gekkota and viviparity across Squamata. We used this new method to demonstrate that there are many shifts in diversification rates across squamates. We then fit various HiSSE submodels and null models to the state and phylogenetic data and reconstructed states under these models. We found that there is no single, consistent signal for state-dependent diversification associated with toepads in gekkotans or viviparity across all squamates. Our reconstructions show limited support for the recently proposed hypotheses that toepads evolved multiple times independently in Gekkota and that transitions from viviparity to oviparity are common in Squamata. Our results highlight the importance of considering an adequate pool of models and null models when estimating diversification rate parameters and reconstructing ancestral states.

Temporal and spatial discordance of programmed cell death-ligand 1 expression and lymphocyte tumor infiltration between paired primary lesions and brain metastases in lung cancer.

BACKGROUND: The dynamics of PD-L1 expression may limit its use as a tissue-based predictive biomarker. We sought to expand our understanding of the dynamics of PD-L1 expression and tumor-infiltrating lymphocytes (TILs) in patients with lung cancer-related brain metastases. EXPERIMENTAL DESIGN: Paired primary lung cancers and brain metastases were identified and assessed for PD-L1 and CD3 expression by immunohistochemistry. Lesions with 5% or greater PD-L1 expression were considered positive. Agreement statistics and the χ(2) or Fisher's exact test were used for analysis. RESULTS: We analyzed 146 paired lesions from 73 cases. There was disagreement of tumor cell PD-L1 expression in 10 cases (14%, κ = 0.71), and disagreement of TIL PD-L1 expression in 19 cases (26%, κ = 0.38). Most paired lesions with discordant tumor cell expression of PD-L1 were obtained 6 or more months apart. When specimens were categorized using a proposed tumor microenvironment categorization scheme based on PD-L1 expression and TILs, there were significant changes in the classifications because many of the brain metastases lacked either PD-L1 expression, tumor lymphocyte infiltration or both even when they were present in the primary lung cancer specimens (P = 0.009). CONCLUSIONS: We identified that there are significant differences between the tumor microenvironment of paired primary lung cancers and brain metastases. When physicians decide to treat patients with lung cancer with a PD-1 or PD-L1 inhibitor, they must do so in the context of the spatial and temporal heterogeneity of the tumor microenvironment.

Multicenter Evaluation of BD Max Enteric Parasite Real-Time PCR Assay for Detection of Giardia duodenalis, Cryptosporidium hominis, Cryptosporidium parvum, and Entamoeba histolytica.

Common causes of chronic diarrhea among travelers worldwide include protozoan parasites. The majority of parasitic infections are caused by Giardia duodenalis, Entamoeba histolytica, Cryptosporidium parvum, and Cryptosporidium hominis Similarly, these species cause the majority of parasitic diarrhea acquired in the United States. Detection of parasites by gold standard microscopic methods is time-consuming and requires considerable expertise; enzyme immunoassays and direct fluorescent-antibody (DFA) stains have lowered hands-on time for testing, but improvements in sensitivity and technical time may be possible with a PCR assay. We performed a clinical evaluation of a multiplex PCR panel, the enteric parasite panel (EPP), for the detection of these common parasites using the BD Max instrument, which performs automated extraction and amplification. A total of 2,495 compliant specimens were enrolled, including 2,104 (84%) specimens collected prospectively and 391 (16%) specimens collected retrospectively. Approximately equal numbers were received in 10% formalin (1,273 specimens) and unpreserved (1,222 specimens). The results from the EPP were compared to those from alternate PCR and bidirectional sequencing (APCR), as well as DFA (G. duodenalis and C. parvum or C. hominis) or trichrome stain (E. histolytica). The sensitivity and specificity for prospective and retrospective specimens combined were 98.2% and 99.5% for G. duodenalis, 95.5% and 99.6 for C. parvum or C. hominis, and 100% and 100% for E. histolytica, respectively. The performance of the FDA-approved BD Max EPP compared well to the reference methods and may be an appropriate substitute for microscopic examination or immunoassays.

Multicenter evaluation of the BD max enteric bacterial panel PCR assay for rapid detection of Salmonella spp., Shigella spp., Campylobacter spp. (C. jejuni and C. coli), and Shiga toxin 1 and 2 genes.

Diarrhea due to enteric bacterial pathogens causes significant morbidity and mortality in the United States and worldwide. However, bacterial pathogens may be infrequently identified. Currently, culture and enzyme immunoassays (EIAs) are the primary methods used by clinical laboratories to detect enteric bacterial pathogens. We conducted a multicenter evaluation of the BD Max enteric bacterial panel (EBP) PCR assay in comparison to culture for the detection of Salmonella spp., Shigella spp., Campylobacter jejuni, and Campylobacter coli and an EIA for Shiga toxins 1 and 2. A total of 4,242 preserved or unpreserved stool specimens, including 3,457 specimens collected prospectively and 785 frozen, retrospective samples, were evaluated. Compared to culture or EIA, the positive percent agreement (PPA) and negative percent agreement (NPA) values for the BD Max EBP assay for all specimens combined were as follows: 97.1% and 99.2% for Salmonella spp., 99.1% and 99.7% for Shigella spp., 97.2% and 98.4% for C. jejuni and C. coli, and 97.4% and 99.3% for Shiga toxins, respectively. Discrepant results for prospective samples were resolved with alternate PCR assays and bidirectional sequencing of amplicons. Following discrepant analysis, PPA and NPA values were as follows: 97.3% and 99.8% for Salmonella spp., 99.2% and 100% for Shigella spp., 97.5% and 99.0% for C. jejuni and C. coli, and 100% and 99.7% for Shiga toxins, respectively. No differences in detection were observed for samples preserved in Cary-Blair medium and unpreserved samples. In this large, multicenter study, the BD Max EBP assay showed superior sensitivity compared to conventional methods and excellent specificity for the detection of enteric bacterial pathogens in stool specimens.

Mycobacterium llatzerense lung infection in a liver transplant recipient: case report and review of the literature.

Nontuberculous mycobacteria are increasingly encountered pathogens in organ transplant recipients. We report the first case of human disease attributed to Mycobacterium llatzerense that occurred in a liver transplant recipient in the midwestern United States who developed pneumonia and describe the treatment of this patient.

Novel fastidious, partially acid-fast, anaerobic Gram-positive bacillus associated with abscess formation and recovered from multiple medical centers.

We report a novel anaerobe causing abscess in four patients at three hospitals. In the clinical specimen, bacilli were branching, Gram positive, and acid fast. The organism grew slowly and was not identified by 16S rRNA sequencing. Our findings support the description of a new genus and species of the suborder Corynebacterineae.

Parity-preserving and magnetic field-resilient superconductivity in InSb nanowires with Sn shells.

Improving materials used to make qubits is crucial to further progress in quantum information processing. Of particular interest are semiconductor-superconductor heterostructures that are expected to form the basis of topological quantum computing. We grew semiconductor indium antimonide nanowires that were coated with shells of tin of uniform thickness. No interdiffusion was observed at the interface between Sn and InSb. Tunnel junctions were prepared by in situ shadowing. Despite the lack of lattice matching between Sn and InSb, a 15-nanometer-thick shell of tin was found to induce a hard superconducting gap, with superconductivity persisting in magnetic field up to 4 teslas. A small island of Sn-InSb exhibits the two-electron charging effect. These findings suggest a less restrictive approach to fabricating superconducting and topological quantum circuits.

Realizing topologically ordered states on a quantum processor.

The discovery of topological order has revised the understanding of quantum matter and provided the theoretical foundation for many quantum error­correcting codes. Realizing topologically ordered states has proven to be challenging in both condensed matter and synthetic quantum systems. We prepared the ground state of the toric code Hamiltonian using an efficient quantum circuit on a superconducting quantum processor. We measured a topological entanglement entropy near the expected value of ­ln2 and simulated anyon interferometry to extract the braiding statistics of the emergent excitations. Furthermore, we investigated key aspects of the surface code, including logical state injection and the decay of the nonlocal order parameter. Our results demonstrate the potential for quantum processors to provide insights into topological quantum matter and quantum error correction.

Understanding nanoparticle self-assembly for a strong improvement in functionality in thin film nanocomposites.

The striking influence of the growth kinetics and substrate enhanced surface mobility on the control of the self-assembly of rare earth tantalate particles (1.5 mol% of nanoparticles in YBa(2)Cu(3)O(7) thin films) is demonstrated. Strongly enhanced flux pinning, control of the anisotropy property and superior critical current densities were achieved. Owing to the unique ability to probe nanoparticle self-assembly through determination of the nature and extent of the anisotropy of the superconducting properties, this system serves as the perfect model system for understanding how to tune and control functional nanocomposite nanostructures for a wide range of multifunctional applications.

Pearls and Pitfalls in MR Enterography Interpretation for Pediatric Patients.

Magnetic resonance (MR) enterography is now the preferred modality for evaluation of acute and chronic presentations of Crohn disease in pediatric patients. There has been increasing standardization in the performance and interpretation of these studies, given the growth in volume and impact on clinical management. This article will focus on technical considerations in the performance of MR enterography in children and adolescents, as well as "do not miss" findings on MR enterography that will impact clinical management and potential problems encountered with MR enterography that may limit its diagnostic utility in some patients.

Correlation between vancomycin MIC values and those of other agents against gram-positive bacteria among patients with bloodstream infections caused by methicillin-resistant Staphylococcus aureus.

An increase in the distribution of vancomycin MIC values among methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) isolates has been noted. It is postulated that the shift in vancomycin MIC values may be associated with a concurrent rise in the MIC values of other anti-MRSA agents. Scant data are available on the correlation between vancomycin MIC values and the MIC values of other anti-MRSA agents. This study examined the correlation between vancomycin MIC values and the MIC values of daptomycin, linezolid, tigecycline, and teicoplanin among 120 patients with bloodstream infections caused by MRSA at a tertiary care hospital between January 2005 and May 2007. For each included patient, the MIC values of the antibiotics under study were determined by the Etest method and were separated into the following two categories: day 1 (index) and post-day 1 (subsequent). For subsequent isolates, the MIC values for each antibiotic from the post-day 1 terminal isolate were used. Among the index isolates, there was a significant correlation (P value, <0.01) between the MIC values for vancomycin and daptomycin and between the MIC values for vancomycin and teicoplanin. The MIC values for daptomycin were significantly correlated with linezolid, tigecycline, and teicoplanin MIC values. Among the 48 patients with subsequent isolates, vancomycin MIC values were significantly correlated with MIC values for daptomycin, linezolid, and teicoplanin (rho value of >or=0.38 for all comparisons). This study documented an association between vancomycin MIC values and the MIC values of other anti-MRSA antibiotics among patients with bloodstream infections caused by MRSA primarily treated with vancomycin.

Causes of the liability insurance crisis.

In this article the reasons for recent dramatic premium increases for liability insurance are explored by examination of available data on industry premiums, losses, and expenses. The suggestions that the premium increases were primarily caused by collusion among insurers, cyclical behavior, or systematic errors in forecasting losses are rejected. Instead, the evidence indicates that the jump in liability insurance premiums is most plausibly due to the growth in the discounted value of expected liability losses.

The original Ivor Lewis two stage esophagectomy revisited in the era of minimally invasive surgery.

BACKGROUND: Esophagectomy has high cardiac and pulmonary complication rates that can reach 43% and 58% respectively. The original Ivor Lewis esophagectomy was a two-stage procedure. We revisited this procedure using a hybrid minimally-invasive approach. METHODS: Thirty-five consecutive patients with esophageal cancer were operated on over an eight-year period. The first stage used laparoscopic mobilization of the stomach, while the second stage used open thoracotomy. Six patients were aborted due to unresectable disease. RESULTS: Twenty-nine patients were studied. The mean operative times for stage-one and stage-two were 108 ±â€¯18 and 226 ±â€¯63 min respectively. All patients were extubated in the operating room. One (3.4%) patients had cardiac complication and one (3.4%) patient had pulmonary complication. CONCLUSION: Metachronous hybrid two-stage esophagectomy was associated with a low rate of cardio-pulmonary complications. It may be considered as an alternative to the one-stage esophagectomy, especially in low-volume centers, to decrease these high-risk cardio-pulmonary complications.

Positive consequences of head and neck cancer: key correlates of finding benefit.

The identification of positive outcomes from adversity has been commonly termed benefit finding. This cross-sectional questionnaire study aimed to identify the extent to which benefit finding occurs among head and neck cancer (HNC) patients and what factors are associated. HNC patients treated 6 months to 10 years previously (n = 76), completed the following measures: the LOT-R, HADS, the Brief COPE, and a measure of benefit finding. Moderate to high levels of benefit finding were reported. Optimism and positive reappraisal were positively associated with benefit finding, with optimism acting independently of positive reappraisal coping. These findings have implications for the development of interventions to maximize positive psychological outcomes after treatment.

The transcriptional landscape of polyploid wheat.

The coordinated expression of highly related homoeologous genes in polyploid species underlies the phenotypes of many of the world's major crops. Here we combine extensive gene expression datasets to produce a comprehensive, genome-wide analysis of homoeolog expression patterns in hexaploid bread wheat. Bias in homoeolog expression varies between tissues, with ~30% of wheat homoeologs showing nonbalanced expression. We found expression asymmetries along wheat chromosomes, with homoeologs showing the largest inter-tissue, inter-cultivar, and coding sequence variation, most often located in high-recombination distal ends of chromosomes. These transcriptionally dynamic genes potentially represent the first steps toward neo- or subfunctionalization of wheat homoeologs. Coexpression networks reveal extensive coordination of homoeologs throughout development and, alongside a detailed expression atlas, provide a framework to target candidate genes underpinning agronomic traits in wheat.

Alpha-plutonium's polycrystalline elastic moduli over its full temperature range.

alpha-plutonium's volume-corrected polycrystal elastic moduli were measured between 18 K and the upper limit of its occurrence, near 400 K. The two independent moduli for a polycrystal-bulk and shear-behave smoothly, indicating no phase transition. Both moduli show the same 50% increase on cooling, an order of magnitude larger than in other metals. The Debye temperature obtained from low-temperature elastic moduli, 207 K, significantly exceeds most previous estimates. The Gruneisen parameter gamma=5.3, obtained from the temperature dependence of the bulk modulus, is intermediate among previous estimates using other approaches, alpha-plutonium's Poisson ratio nu is low: 0.18, nearly temperature independent, and its small decrease on warming opposes usual behavior. The high gamma, large but equal bulk modulus and shear modulus fractional stiffening on cooling, and near-temperature-invariant nu are attributed to a single mechanism: 5-f electron localization-delocalization.

The loss of CCR6+ and CD161+ CD4+ T-cell homeostasis contributes to disease progression in SIV-infected rhesus macaques.

Although previous studies have shown that CD4+ T cells expressing CCR6 and CD161 are depleted from blood during HIV infection, the mechanisms underlying their loss remain unclear. In this study, we investigated how the homeostasis of CCR6+ and CD161+ CD4+ T cells contributes to SIV disease progression and the mechanisms responsible for their loss from circulation. By comparing SIV infection in rhesus macaques (RMs) and natural host sooty mangabeys (SMs), we found that the loss of CCR6+ and CD161+ CD4+ T cells from circulation is a distinguishing feature of progressive SIV infection in RMs. Furthermore, while viral infection critically contributes to the loss of CD161+CCR6-CD4+ T cells, a redistribution of CCR6+CD161- and CCR6+CD161+CD4+ T cells from the blood to the rectal mucosa is a chief mechanism for their loss during SIV infection. Finally, we provide evidence that the accumulation of CCR6+CD4+ T cells in the mucosa is damaging to the host by demonstrating their reduction from this site following initiation of antiretroviral therapy in SIV-infected RMs and their lack of accumulation in SIV-infected SMs. These data emphasize the importance of maintaining CCR6+ and CD161+ CD4+ T-cell homeostasis, particularly in the mucosa, to prevent disease progression during pathogenic HIV/SIV infection.

Observation of a topologically non-trivial surface state in half-Heusler PtLuSb (001) thin films.

The discovery of topological insulators, materials with bulk band gaps and protected cross-gap surface states in compounds such as Bi2Se3, has generated much interest in identifying topological surface states (TSSs) in other classes of materials. In particular, recent theoretical calculations suggest that TSSs may be found in half-Heusler ternary compounds. If experimentally realizable, this would provide a materials platform for entirely new heterostructure spintronic devices that make use of the structurally identical but electronically varied nature of Heusler compounds. Here we show the presence of a TSS in epitaxially grown thin films of the half-Heusler compound PtLuSb. Spin- and angle-resolved photoemission spectroscopy, complemented by theoretical calculations, reveals a surface state with linear dispersion and a helical tangential spin texture consistent with previous predictions. This experimental verification of topological behaviour is a significant step forward in establishing half-Heusler compounds as a viable material system for future spintronic devices.

Inferences on the genome structure of progenitor maize through comparative analysis of rice, maize and the domesticated panicoids.

Corn and rice genetic linkage map alignments were extended and refined by the addition of 262 new, reciprocally mapped maize cDNA loci. Twenty chromosomal rearrangements were identified in maize relative to rice and these included telomeric fusions between rice linkage groups, nested insertion of rice linkage groups, intrachromosomal inversions, and a nonreciprocal translocation. Maize genome evolution was inferred relative to other species within the Panicoideae and a progenitor maize genome with eight linkage groups was proposed. Conservation of composite linkage groups indicates that the tetrasomic state arose during maize evolution either from duplication of one progenitor corn genome (autoploidy) or from a cross between species that shared the composite linkages observed in modern maize (alloploidy). New evidence of a quadruplicated homeologous segment on maize chromosomes 2 and 10, and 3 and 4, corresponded to the internally duplicated region on rice chromosomes 11 and 12 and suggested that this duplication in the rice genome predated the divergence of the Panicoideae and Oryzoideae subfamilies. Charting of the macroevolutionary steps leading to the modern maize genome clarifies the interpretation of intercladal comparative maps and facilitates alignments and genomic cross-referencing of genes and phenotypes among grass family members.