Unusual magnetotransport in twisted bilayer graphene from strain-induced open Fermi surfaces.

Anisotropic hopping in a toy Hofstadter model was recently invoked to explain a rich and surprising Landau spectrum measured in twisted bilayer graphene away from the magic angle. Suspecting that such anisotropy could arise from unintended uniaxial strain, we extend the Bistritzer-MacDonald model to include uniaxial heterostrain and present a detailed analysis of its impact on band structure and magnetotransport. We find that such strain strongly influences band structure, shifting the three otherwise-degenerate van Hove points to different energies. Coupled to a Boltzmann magnetotransport calculation, this reproduces previously unexplained nonsaturating [Formula: see text] magnetoresistance over broad ranges of density near filling [Formula: see text] and predicts subtler features that had not been noticed in the experimental data. In contrast to these distinctive signatures in longitudinal resistivity, the Hall coefficient is barely influenced by strain, to the extent that it still shows a single sign change on each side of the charge neutrality point-surprisingly, this sign change no longer occurs at a van Hove point. The theory also predicts a marked rotation of the electrical transport principal axes as a function of filling even for fixed strain and for rigid bands. More careful examination of interaction-induced nematic order versus strain effects in twisted bilayer graphene could thus be in order.

Unusual magnetotransport in twisted bilayer graphene.

SignificanceWhen two sheets of graphene are twisted to the magic angle of 1.1∘, the resulting flat moiré bands can host exotic correlated electronic states such as superconductivity and ferromagnetism. Here, we show transport properties of a twisted bilayer graphene device at 1.38∘, far enough above the magic angle that we do not expect exotic correlated states. Instead, we see several unusual behaviors in the device's resistivity upon tuning both charge carrier density and perpendicular magnetic field. We can reproduce these behaviors with a surprisingly simple model based on Hofstadter's butterfly. These results shed light on the underlying properties of twisted bilayer graphene.

Measured Potential Profile in a Quantum Anomalous Hall System Suggests Bulk-Dominated Current Flow.

Ideally, quantum anomalous Hall systems should display zero longitudinal resistance. Yet in experimental quantum anomalous Hall systems elevated temperature can make the longitudinal resistance finite, indicating dissipative flow of electrons. Here, we show that the measured potentials at multiple locations within a device at elevated temperature are well described by solution of Laplace's equation, assuming spatially uniform conductivity, suggesting nonequilibrium current flows through the two-dimensional bulk. Extrapolation suggests that at even lower temperatures current may still flow primarily through the bulk rather than, as had been assumed, through edge modes. An argument for bulk current flow previously applied to quantum Hall systems supports this picture.

Complex interventions can increase osteoporosis investigations and treatment: a systematic review and meta-analysis.

Osteoporosis is affecting over 200 million people worldwide. Despite available guidelines, care for these patients remains sub-optimal. We developed an osteoporosis tool to address the multiple dimensions of chronic disease management. Findings from its evaluation showed a significant increase from baseline in osteoporosis investigations and treatment, so we are revising this tool to include multiple chronic conditions including an update of evidence about osteoporosis. Our objectives were to conduct a systematic review of osteoporosis interventions in adults at risk for osteoporosis. We searched bibliometric databases for randomized controlled trials (RCTs) in any language evaluating osteoporosis disease management interventions in adults at risk for osteoporosis. Reviewer pairs independently screened citations and full-text articles, extracted data, and assessed risk of bias. Analysis included random effects meta-analysis. Primary outcomes were osteoporosis investigations and treatment, and fragility fractures. Fifty-five RCTs and one companion report were included in the analysis representing 165,703 patients. Our findings from 55 RCTs and 18 sub-group meta-analyses showed that complex implementation interventions with multiple components consisting of at least education + feedback + follow-up significantly increased the initiation of osteoporosis medications, and interventions with at least education + follow-up significantly increased the initiation of osteoporosis investigations. No significant impact was found for any type of intervention to reduce fracture. Complex interventions that include at least education + follow-up or feedback have the most potential for increasing osteoporosis investigations and treatment. Patient education appears to be an important component in osteoporosis disease management.

Thermocoagulation of the Medial Branch of the Dorsal Branch of the Lumbal Spinal Nerve: Flouroscopy Versus CT.

Objective: For radiofrequency neurotomy of the medial branch of the lumbar dorsal rami, physicians use techniques guided either by fluoroscopy or computerized tomography (CT), and advocate for their respective techniques. Crucial to the choice of technique is how well each can capture the target nerve. The present study was, therefore, undertaken to assess in cadavers the accuracy of fluoroscopic-guided and CT-guided techniques. Design: In10 cadavers preserved with Thiel's method, electrodes with 10mm active tips were placed in supine position on the right using a fluoroscopic-guided technique, and on the left using a CT-guided technique. Using a special dissection approach, the relationship between the target nerve and the tip of the electrode was revealed. The displacement between electrode and the nerve, and the extent to which the electrode was parallel to the nerve, were measured with callipers. Results: Under fluoroscopy guidance, electrodes were placed accurately beside the nerve, and were parallel to it for 9 ±1.9 mm. In only two cases did the electrode pass too deeply. Under CT guidance, electrodes often failed to reach the nerve, but when they did they were parallel to it for only 3.2 ± 3.2 mm. In seven cases, the electrode passed too deeply beyond the target nerve. Conclusion: The fluoroscopy-guided technique can be relied upon to achieve optimal placement of electrodes on the lumbar medial branches. The CT-guided technique fails to do so, and should not be used in practice until a modified version has been developed and validated.

Potential energy landscape of the two-dimensional XY model: higher-index stationary points.

The application of numerical techniques to the study of energy landscapes of large systems relies on sufficient sampling of the stationary points. Since the number of stationary points is believed to grow exponentially with system size, we can only sample a small fraction. We investigate the interplay between this restricted sample size and the physical features of the potential energy landscape for the two-dimensional XY model in the absence of disorder with up to N = 100 spins. Using an eigenvector-following technique, we numerically compute stationary points with a given Hessian index I for all possible values of I. We investigate the number of stationary points, their energy and index distributions, and other related quantities, with particular focus on the scaling with N. The results are used to test a number of conjectures and approximate analytic results for the general properties of energy landscapes.

COX-2, p16 and Ki67 expression in DCIS, microinvasive and early invasive breast carcinoma with extensive intraductal component.

BACKGROUND: Recent studies have showed a significant association between the combination of COX-2, p16 and Ki67 overexpression and incidence of subsequent invasive carcinoma in a subgroup of treated ductal carcinoma in situ (DCIS) and the indicated prognostic value of COX-2, p16 and Ki67 in early breast cancer. Based on the continual model of carcinogenesis and the mentioned results, we hypothesize, that if COX-2, p16 and Ki67 expression is prognostic for DCIS future behaviour, the expression level of the markers correlates also with different stages of breast carcinomas such as DCIS, microinvasive cancer and early invasive cancer with an extensive intraductal compound. The aim of this study was to compare the expression of COX-2, p16 and Ki67 in different stages of breast carcinoma such as pure DCIS, microinvasive cancer (T1mic) and invasive ductal carcinoma with an extensive intraductal component (IDC with EIC). The expression was assessed only in in situ component of the three subgroups (DCIS, T1mic, EIC) in order to show a possible correlation of COX-2, p16 and Ki67 with different stages of carcinogenesis. METHODS: We carried out a retrospective study using immunohistochemical staining to evaluate the expression of the markers COX-2, p16 and Ki67 in in situ lesions within three subgroups of tumors with the rising extant of invasive compound: in pure DCIS, microinvasive carcinoma (T1mic) and invasive carcinoma with extensive in situ component (IDC with EIC). Additionally, we performed a correlation analysis between the tumor subgroups and patients history data (age, parity, age of menarche, family and personal cancer history, breast feeding lengths, contraception intake, chest irradiation) as well as some of the tumor characteristics (tumor grade, multicentricity, necrosis). RESULTS: Distribution of p16 expression differed significantly among the three diagnoses. P16 score 1 was highest in the DCIS group whereas the lowest proportion was in IDC and p16 overexpression (score 2, 3) maintained this tendency (overexpression proportion in DCIS < T1mic < IDC), though this was not significant. The frequency of COX-2 and p16 overexpression (phenotype COX-2+p16+) was higher in EIC within invasive carcinoma in comparison to DCIS and T1mic and was rising gradually with the severity of the diagnosis (proportion in DCIS < T1mic < IDC). CONCLUSION: This is the first published study ever assessing the expression of COX-2, p16 and Ki67 markers in different breast tumors containing DCIS compound. Our results showed an increasing expression pattern of COX-2 and p16 with the rising severity of the diagnosis (expression was measured exclusively in in situ lesions within tumors containing different extant of invasiveness). The same relationship was showed for p16 marker alone. These data support different expression pattern of COX-2 and p16 markers in combination and p16 marker alone in "in situ lesions" according to the stage of carcinogenesis. This fact might be useful in the evaluation of further behaviour of early breast tumors (Tab. 3, Fig. 8, Ref. 29).

Field applicability of Compound-Specific Isotope Analysis (CSIA) for characterization and quantification of in situ contaminant degradation in aquifers.

Microbial processes govern the fate of organic contaminants in aquifers to a major extent. Therefore, the evaluation of in situ biodegradation is essential for the implementation of Natural Attenuation (NA) concepts in groundwater management. Laboratory degradation experiments and biogeochemical approaches are often biased and provide only indirect evidence of in situ degradation potential. Compound-Specific Isotope Analysis (CSIA) is at present among the most promising tools for assessment of the in situ contaminant degradation within aquifers. One- and two-dimensional (2D) CSIA provides qualitative and quantitative information on in situ contaminant transformation; it is applicable for proving in situ degradation and characterizing degradation conditions and reaction mechanisms. However, field application of CSIA is challenging due to a number of influencing factors, namely those affecting the observed isotope fractionation during biodegradation (e.g., non-isotope-fractionating rate-limiting steps, limited bioavailability), potential isotope effects caused by processes other than biodegradation (e.g., sorption, volatilization, diffusion), as well as non-isotope-fractionating physical processes such as dispersion and dilution. This mini-review aims at guiding practical users towards the sound interpretation of CSIA field data for the characterization of in situ contaminant degradation. It focuses on the relevance of various constraints and influencing factors in CSIA field applications and provides advice on when and how to account for these constraints. We first evaluate factors that can influence isotope fractionation during biodegradation, as well as potential isotope-fractionating and non-isotope-fractionating physical processes governing observed isotope fractionation in the field. Finally, the potentials of the CSIA approach for site characterization and the proper ways to account for various constraints are illustrated by means of a comprehensive CSIA field study at the benzene, toluene, ethylbenzene, and xylene (BTEX)-contaminated site Zeitz.

Observation of a phase transition within the domain walls of ferromagnetic Co3Sn2S2.

The ferromagnetic phase of Co3Sn2S2 is widely considered to be a topological Weyl semimetal, with evidence for momentum-space monopoles of Berry curvature from transport and spectroscopic probes. As the bandstructure is highly sensitive to the magnetic order, attention has focused on anomalies in magnetization, susceptibility and transport measurements that are seen well below the Curie temperature, leading to speculation that a "hidden" phase coexists with ferromagnetism. Here we report spatially-resolved measurements by Kerr effect microscopy that identify this phase. We find that the anomalies coincide with a deep minimum in domain wall (DW) mobility, indicating a crossover between two regimes of DW propagation. We demonstrate that this crossover is a manifestation of a 2D phase transition that occurs within the DW, in which the magnetization texture changes from continuous rotation to unidirectional variation. We propose that the existence of this 2D transition deep within the ferromagnetic state of the bulk is a consequence of a giant quality factor for magnetocrystalline anisotropy unique to this compound. This work broadens the horizon of the conventional binary classification of DWs into Bloch and Néel walls, and suggests new strategies for manipulation of domain walls and their role in electron and spin transport.

Topography of the lumbar sympathetic trunk in normal lumbar spines and spines with spondylophytes.

BACKGROUND: Degenerative processes of the lumbar spine may change the position of the sympathetic trunk which might cause failure of sympathetic blocks owing to inadequate distribution of local anaesthetic. METHODS: The retroperitoneal spaces of 56 cadavers [24 males and 32 females; 79 (10) yr] embalmed with Thiel's method were investigated by dissection. The course of the lumbar sympathetic trunk (LST) was documented from the diaphragmatic level to the linea terminalis. Topography of the large vessels and the psoas muscle was documented. In the case of spondylophytes, the location or direction of displacement of the trunk was regarded with special interest. RESULTS: The LST entered the retroperitoneal space at the level of the vertebral body of L2 in 70 of the 112 sides and showed the most consistent relationship with the medial margin of the psoas muscle at intervertebral disc level L2/3. On 11 spines with spondylophytes, the sympathetic trunk was dislocated to the most ventrolateral point of the spondylophyte in 12 cases, in six cases dorsolaterally, and in one case ventromedially. The more the sympathetic chain departed at the vertebral body level, the more the body developed a concavity by loss of height. CONCLUSIONS: Spondylophytes influenced the location of the LST and the distribution of the local anaesthetic. The local anaesthetic should wash around the spondylophyte to reach all possible locations of the chain. The medial margin of the psoas muscle was confirmed to be a consistent reference point at intervertebral disc level L2/3.

Gaps in anaphylaxis management at the level of physicians, patients, and the community: a systematic review of the literature.

Diagnosis and management of anaphylaxis can be a challenge because reactions are often unexpected and progress quickly. The focus of anaphylaxis management has mostly been on the acute episode, with little attention given to the long-term management of patients at risk. This is compounded by conflicting information in current guidelines and a general lack of agreement among clinicians about which management strategies are the most appropriate. We systematically reviewed the literature to identify and summarize studies that investigated gaps in anaphylaxis management. Our search included MEDLINE, EMBASE, CINAHL, and Evidence-Based Medicine Reviews. Studies were included if they addressed an outcome describing gaps in anaphylaxis knowledge, education, anaphylaxis management, and quality of life (QOL). Populations of interest were health care professionals involved in the care of patients at risk for anaphylaxis, and patients of any age, their parents, caregivers, and teachers in primary care, hospital or community settings. Of 5014 citations that were identified, the final 59 studies (selected from 75 full-text articles) met the inclusion criteria. Two hundred and two gaps were identified and classified according to major themes: gaps in knowledge and anaphylaxis management (physicians and patients); gaps in follow-up care (physicians); and QOL of patients and caregivers. Findings from this systematic review revealed gaps in anaphylaxis management at the level of physicians, patients, and the community. Findings will be used to provide a basis for developing interventional strategies to help address these deficiencies.

Management of anaphylaxis in primary care: Canadian expert consensus recommendations.

BACKGROUND: Anaphylaxis is often managed inadequately. We used findings from a systematic review of gaps in anaphylaxis management to develop evidence-based recommendations for gaps rated as clinically important by a panel of Canadian allergy experts. METHODS: The nominal group technique (NGT) consensus methodology was used to develop evidence-based recommendations for the management of anaphylaxis in primary care. Physician-specific gaps from our systematic review were prioritized by consensus meeting participants in two rounds, which involved the rating, discussion, and re-rating of gaps. Using current anaphylaxis guidelines, recommendations were then developed for each category of gaps that were identified by the panel as clinically important. RESULTS: Thirty unique physician gaps from the systematic review were categorized according to gaps of knowledge and anaphylaxis practice behaviors. The panel rated diagnosis of anaphylaxis, and when and how to use epinephrine auto-injectors as clinically important knowledge gaps; and rated infrequent or delayed epinephrine administration, low rate of auto-injector prescription, and infrequent or no referrals to allergy specialists after a reaction as important practice behavior gaps. Evidence from four guidelines was used to support the consensus recommendation statements for three resulting categories of gap themes: anaphylaxis management, epinephrine use, and follow-up care. CONCLUSION: We used an NGT consensus methodology to develop an educational resource for primary care physicians and allergists to better understand how to manage patients with anaphylaxis. Next steps include testing our findings against observed data in primary care settings and to develop other strategies or tools to overcome gaps in anaphylaxis management.

Combustion metamorphism in southern california.

In several places in Southern California bituminous sediments of the Monterey Formation-siliceous shales, phosphatic rocks, dolomites, and arkoses-were affected during the Pleistocene and as late as the l9th century by spontaneous subsurface combustion of organic matter, during which temperatures up to 1600 degrees C were reached. This oxidative heating (combustion metamorphism) affected rock complexes over areas of tens of square kilometers that tend to occur in clusters. As a result of these processes, the rocks recrystallized and partially melted to form pseudomagmas which intruded the country rocks. The chemical compositions of these melts differ from those of igneous magmas. Acid and intermediate siliceous melts as well as phosphatic melts have formed. These two types are generally immiscible. The following high-temperature minerals were determined: alpha- and beta-cristobalite, quartz, calcic plagioclase, diopsidic pyroxene, wollastonite, cordierite, graphite, fluorapatite, and fluorite; at lower temperature pyrite, gypsum, aragonite, calcite, jarosite, and hexahydrite crystallized.

Constraints on the formation of sedimentary dolomite.

The experimental replacement of calcite and aragonite by dolomite under a variety of conditions indicates that dolomitization can take place in marine and lacustrine environments under two conditions: (i) low dissolved sulfate concentrations and (ii) insubstantial contemporaneous silica diagenesis. Common sites for dolomite formation are areas where the dissolved sulfate concentration is reduced by microbial sulfate reduction, through the mixing of seawater with large amounts of fresh water, or where low-sulfate alkaline lacustrine environments prevail. Even under these conditions, dolomite formation may be inhibited by the concurrent transformation of opal-A (amorphous silica) to opal-CT (disordered cristobalite and tridymite), whereas the subsequent transformation of opal-CT to quartz favors the formation of dolomite.

The Precursor of the Cretaceous-Tertiary Boundary Clays at Stevns Klint, Denmark, and DSDP Hole 465A.

Results of detailed mineralogical, chemical, and oxygen isotope analyses of the clay minerals and zeolites from two Cretaceous-Tertiary (K/T) boundary regions, Stevns Klint, Denmark, and Deep Sea Drilling Project (DSDP) Hole 465A in the north central Pacific Ocean, are presented. In the central part of the Stevns Klint K/T boundary layer, the only clay mineral detected by x-ray diffraction is a pure smectite with > 95 percent expandable layers. No detrital clay minerals or quartz were observed in the clay size fraction in these beds, whereas the clay minerals above and below the boundary layer are illite and mixed-layer smectite-illite of detrital origin as well as quartz. The mineralogical purity of the clay fraction, the presence of smectite only at the boundary, and the delta(18)O value of the smectite (27.2 +/- 0.2 per mil) suggest that it formed in situ by alteration of glass. Formation from impact rather than from volcanic glass is supported by its major element chemistry. The high content of iridium and other siderophile elements is not due to the cessation of calcium carbonate deposition and resulting slow sedimentation rates. At DSDP Hole 465A, the principal clay mineral in the boundary zone (80 to 143 centimeters) is a mixed-layer smectite-illite with >/=90 percent expandable layers, accompanied by some detrital quartz and small amounts of a euhedral authigenic zeolite (clinoptilolite). The mixed-layer smectite-illite from the interval 118 to 120 centimeters in the zone of high iridium abundance has a very low rare earth element content; the negative cerium anomaly indicates formation in the marine environment. This conclusion is corroborated by the delta(18)O value of this clay mineral (27.1 +/- 0.2 per mil). Thus, this mixed-layer smectite-illite formed possibly from the same glass as the K/T boundary smectite at Stevns Klint, Denmark.

Copper artifacts: correlation with source types of copper ores.

Six out of eight minor chemical elements, determined by spectroscopic and neutron-activation techniques, were found to be critical in computing a probability that a given copper artifact was derived from one of three types of copper ore: native metal, oxidized ore, reduced ore. Two elements, gold and tin, were apparently alloyed deliberately in many artifacts from both the Old World and the New World.

Laminated diatomaceous sediments from the guaymas basin slope (central gulf of california): 250,000-year climate record.

During Deep Sea Drilling Project-International Program of Ocean Drilling leg 64, December 1978 to January 1979, the initial test of the Deep Sea Drilling Project's hydraulic piston corer obtained an almost undisturbed section from a 152-meter hole into the sediments of the oxygen minimum zone at a depth of 655 meters along the Guaymas slope in the central Gulf of California. The section records variations in climate, productivity, and circulation for more than 250,000 years of Late Pleistocene to Holocene history with recordings of seasonal variations in these parameters in the laminated sections.

East pacific rise: hot springs and geophysical experiments.

Hydrothermal vents jetting out water at 380 degrees +/- 30 degrees C have been discovered on the axis of the East Pacific Rise. The hottest waters issue from mineralized chimneys and are blackened by sulfide precipitates. These hydrothermal springs are the sites of actively forming massive sulfide mineral deposits. Cooler springs are clear to milky and support exotic benthic communities of giant tube worms, clams, and crabs similar to those found at the Galápagos spreading center. Four prototype geophysical experiments were successfully conducted in and near the vent area: seismic refraction measurements with both source (thumper) and receivers on the sea floor, on-bottom gravity measurements, in situ magnetic gradiometer measurements from the submersible Alvin over a sea-floor magnetic reversal boundary, and an active electrical sounding experiment. These high-resolution determinations of crustal properties along the spreading center were made to gain knowledge of the source of new oceanic crust and marine magnetic anomalies, the nature of the axial magma chamber, and the depth of hydrothermal circulation.

Stromal coexpression of uPA/PAI-1 protein predicts poor disease outcome in endocrine-treated postmenopausal patients with receptor-positive early breast cancer.

BACKGROUND: To evaluate whether uPA/PAI-1 protein in hormone receptor-positive (HR+) breast tumor can predict prognosis in early breast cancer (BC). METHODS: 606 women with HR + BC who had ≥5 years of endocrine therapy and in whom tumor tissue was available were included in this analysis. Stromal uPA/PAI-1 protein expression was evaluated by immunohistochemistry and correlated with distant recurrence-free survival (DRFS) and overall survival (OS). RESULTS: Stromal uPA was detected in 292/538 tumors (54.3%) while 269/505 samples (53.3%) exhibited stromal PAI-1. Co-expression of both proteins was found in 163/437 (37.3%) samples. Stromal uPA/PAI-1 co-expression was not associated with tumor size, age, nodal status, grading, or receptor status. Tumor stroma with both uPA and PAI-1 protein expression were more likely to have a shorter DRFS (HR: 1.87; 95%CI 1.18-2.96; p = 0.007) and OS (HR: 1.29; 95%CI 0.93-1.80; p = 0.129) than women without uPA/PAI-1 co-expression. After a median follow-up of 10 years, women with uPA/PAI-1-positive tumors experienced a significantly shorter DRFS (86.5% vs 72.4%; p < 0.001) and OS (70.4% vs 58.9%; p = 0.020) compared to women with uPA/PAI-1 negative tumors. CONCLUSION: Stromal co-expression of uPA and PAI-1 in breast cancer predicts poor DRFS and OS in postmenopausal women with HR + early-stage BC who receive endocrine therapy.

Emergent ferromagnetism near three-quarters filling in twisted bilayer graphene.

When two sheets of graphene are stacked at a small twist angle, the resulting flat superlattice minibands are expected to strongly enhance electron-electron interactions. Here, we present evidence that near three-quarters ([Formula: see text]) filling of the conduction miniband, these enhanced interactions drive the twisted bilayer graphene into a ferromagnetic state. In a narrow density range around an apparent insulating state at [Formula: see text], we observe emergent ferromagnetic hysteresis, with a giant anomalous Hall (AH) effect as large as 10.4 kilohms and indications of chiral edge states. Notably, the magnetization of the sample can be reversed by applying a small direct current. Although the AH resistance is not quantized, and dissipation is present, our measurements suggest that the system may be an incipient Chern insulator.