Electron-Beam Manipulation of Silicon Dopants in Graphene

The direct manipulation of individual atoms in materials using scanning probe microscopy has been a seminal achievement of nanotechnology. Recent advances in imaging resolution and sample stability have made scanning transmission electron microscopy a promising alternative for single-atom manipulation of covalently bound materials. Pioneering experiments using an atomically focused electron beam have demonstrated the directed movement of silicon atoms over a handful of sites within the graphene lattice. Here, we achieve a much greater degree of control, allowing us to precisely move silicon impurities along an extended path, circulating a single hexagon, or back and forth between the two graphene sublattices. Even with manual operation, our manipulation rate is already comparable to the state-of-the-art in any atomically precise technique. We further explore the influence of electron energy on the manipulation rate, supported by improved theoretical modeling taking into account the vibrations of atoms near the impurities, and implement feedback to detect manipulation events in real time. In addition to atomic-level engineering of its structure and properties, graphene also provides an excellent platform for refining the accuracy of quantitative models and for the development of automated manipulation.Comment: 5 figures, 4 supporting figure

Three-dimensional ab initio description of vibration-assisted electron knock-on displacements in graphene

peer reviewedTransmission electron microscopy characterization may damage materials, but an electron beam can also induce interesting dynamics. Elastic knock-on is the main electron irradiation damage mechanism in metals including graphene, and although atomic vibrations influence its cross section, only the out-of-plane direction has been considered so far. Here, we present a full three-dimensional first-principles theory of knock-on displacements including the effect of temperature on vibrations to describe dynamics into arbitrary directions. We validate the model with previously precisely measured knock-on damage of pristine graphene, where we show that the isotropic out-of-plane approximation correctly describes the cross section. We then apply our methodology to reversible jumps of pyridinic nitrogen atoms, whose probability under irradiation is measured at 55 and 60 keV. Direct displacement requiring a high emission angle and an alternative pathway via intermittent N adatom creation and recombination are computationally explored but are unable to explain the observed rates, implying stronger inelastic effects at the defect than in pristine graphene

In-hospital Outcomes of Attempting More Than One Chronic Total Coronary Occlusion Through Percutaneous Intervention During the Same Procedure

The frequency and outcomes of patients who underwent chronic total occlusion (CTO) percutaneous coronary intervention (PCI) of more than one CTO during the same procedure have received limited study. We compared the clinical and angiographic characteristics and procedural outcomes of patients who underwent treatment of single versus >1 CTOs during the same procedure in 20 centers from the United States, Europe, and Russia. A total of 2,955 patients were included: mean age was 65 ± 10 years and 85% were men with high prevalence of previous myocardial infarction (46%), and previous coronary artery bypass graft surgery (33%). More than one CTO lesions were attempted during the same procedure in 58 patients (2.0%) and 70% of them were located in different major epicardial arteries. Compared with patients who underwent PCI of a single CTO, those who underwent PCI of >1 CTOs during the same procedure had similar J-CTO (2.4 ± 1.3 vs 2.5 ± 1.3, p = 0.579) and Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (1.5 ± 1.2 vs 1.3 ± 1.0 p = 0.147) scores. The multi-CTO PCI group had similar technical success (86% vs 87%, p = 0.633), but higher risk of in-hospital major complications (10.3% vs 2.7%, p = 0.005), and consequently numerically lower procedural success (79% vs 85%, p = 0.197). The multi-CTO PCI group had higher in-hospital mortality (5.2% vs 0.5%, p = 0.005) and stroke (5.2%vs 0.2%, p 1 CTO lesions requiring revascularization, as treatment during a single procedure was associated with higher risk for periprocedural complications

Genome-wide association study of primary tooth eruption identifies pleiotropic loci associated with height and craniofacial distances

Twin and family studies indicate that the timing of primary tooth eruption is highly heritable, with estimates typically exceeding 80%. To identify variants involved in primary tooth eruption we performed a population based genome-wide association study of ‘age at first tooth’ and ‘number of teeth’ using 5998 and 6609 individuals respectively from the Avon Longitudinal Study of Parents and Children (ALSPAC) and 5403 individuals from the 1966 Northern Finland Birth Cohort (NFBC1966). We tested 2,446,724 SNPs imputed in both studies. Analyses were controlled for the effect of gestational age, sex and age of measurement. Results from the two studies were combined using fixed effects inverse variance meta-analysis. We identified a total of fifteen independent loci, with ten loci reaching genome-wide significance (p<5x10−8) for ‘age at first tooth’ and eleven loci for ‘number of teeth’. Together these associations explain 6.06% of the variation in ‘age of first tooth’ and 4.76% of the variation in ‘number of teeth’. The identified loci included eight previously unidentified loci, some containing genes known to play a role in tooth and other developmental pathways, including a SNP in the protein-coding region of BMP4 (rs17563, P= 9.080x10−17). Three of these loci, containing the genes HMGA2, AJUBA and ADK, also showed evidence of association with craniofacial distances, particularly those indexing facial width. Our results suggest that the genome-wide association approach is a powerful strategy for detecting variants involved in tooth eruption, and potentially craniofacial growth and more generally organ development

TCT-170 Development and Validation of a Scoring System for Predicting Clinical Coronary Artery Perforation During Percutaneous Coronary Interventions of Chronic Total Occlusions: The PROGRESS-CTO Perforation Score

Background: Coronary artery perforation is a feared complication of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) and often leads to serious adverse clinical events. Methods: We analyzed clinical and angiographic parameters from 9,618 CTO PCIs in the PROGRESS-CTO (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention). Logistic regression prediction modeling was used to identify independently associated variables, and models were internally validated with bootstrapping. Clinical coronary artery perforation was defined as any perforation requiring treatment. Results: The incidence of clinical coronary perforation was 3.8% (n = 367). Five factors were independently associated with perforation and were included in the score: patient age ≥ 65 years, +1 point (OR: 1.79; 95% CI: 1.37-2.33); moderate or severe calcification, +1 point (OR: 1.85; 95% CI: 1.41-2.42); blunt or no stump, +1 point (OR: 1.45; 95% CI: 1.10-1.92); use of antegrade dissection and re-entry strategy, +1 point (OR: 2.43; 95% CI: 1.61-3.69); and use of the retrograde approach, +2 points (OR: 4.02; 95% CI: 2.95-5.46). The resulting score showed acceptable performance on receiver-operating characteristic curve (area under the curve: 0.741; 95% CI: 0.712-0.773). The Hosmer-Lemeshow test indicated good fitness (P = 0.991), and internal validation with bootstrapping demonstrated a good agreement with the model (observed area under the curve: 0.736; 95% bias-corrected CI: 0.706-0.767). Conclusions: The PROGRESS-CTO perforation score is a useful tool for prediction of clinical coronary perforation in CTO PCI. Categories: CORONARY: Complex and Higher Risk Procedures for Indicated Patients (CHIP

The contribution of tropical cyclones to the atmospheric branch of Middle America's hydrological cycle using observed and reanalysis tracks

Middle America is affected by tropical cyclones (TCs) from the Eastern Pacific and the North Atlantic Oceans. We characterize the regional climatology (1998-2016) of the TC contributions to the atmospheric branch of the hydrological cycle, from May to December. TC contributions to rainfall are quantified using Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) product 3B42 and TC tracks derived from three sources: the International Best Track Archive for Climate Stewardship (IBTrACS), and an objective feature tracking method applied to the Japanese 55-year and ERA-Interim reanalyses. From July to October, TCs contribute 10-30% of rainfall over the west and east coast of Mexico and central Mexico, with the largest monthly contribution during September over the Baja California Peninsula (up to 90%). TCs are associated with 40-60% of daily extreme rainfall (above the 95th percentile) over the coasts of Mexico. IBTrACS and reanalyses agree on TC contributions over the Atlantic Ocean but disagree over the Eastern Pacific Ocean and continent; differences over the continent are mainly attributed to discrepancies in TC tracks in proximity to the coast and TC lifetime. Reanalysis estimates of TC moisture transports show that TCs are an important moisture source for the regional water budget. TC vertically integrated moisture flux (VIMF) convergence can turn regions of weak VIMF divergence by the mean circulation into regions of weak VIMF convergence. We discuss deficiencies in the observed and reanalysis TC tracks, which limit our ability to quantify robustly the contribution of TCs to the regional hydrological cycle

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO