A microscopic 2D lattice model of dimer granular compaction with friction

We study by Monte Carlo simulation the compaction dynamics of hard dimers in 2D under the action of gravity, subjected to vertical and horizontal shaking, considering also the case in which a friction force acts for horizontal displacements of the dimers. These forces are modeled by introducing effective probabilities for all kinds of moves of the particles. We analyze the dynamics for different values of the time $\tau$ during which the shaking is applied to the system and for different intensities of the forces. It turns out that the density evolution in time follows a stretched exponential behavior if $\tau$ is not very large, while a power law tail develops for larger values of $\tau$. Moreover, in the absence of friction, a critical value $\tau^*$ exists which signals the crossover between two different regimes: for $\tau < \tau^*$ the asymptotic density scales with a power law of $\tau$, while for $\tau > \tau^*$ it reaches logarithmically a maximal saturation value. Such behavior smears out when a finite friction force is present. In this situation the dynamics is slower and lower asymptotic densities are attained. In particular, for significant friction forces, the final density decreases linearly with the friction coefficient. We also compare the frictionless single tap dynamics to the sequential tapping dynamics, observing in the latter case an inverse logarithmic behavior of the density evolution, as found in the experiments.Comment: 10 pages, 15 figures, to be published in Phys. Rev.

Prevalence and consequences of noncardiac incidental findings on preprocedural imaging in the workup for transcatheter aortic valve implantation, renal sympathetic denervation, or MitraClip implantation

Background: Dedicated data on the prevalence of incidental findings (IF) stratified according to overall clinical relevance and their subsequent correlation to outcome are lacking. The aim of the present study was to describe the prevalence and consequences of noncardiac IF on computed tomography or magnetic resonance imaging in the workup for interventional cardiovascular procedures. Methods: A total of 916 patients underwent preprocedural computed tomography or magnetic resonance imaging in the workup for transcatheter aortic valve implantation (TAVI), renal sympathetic denervation (RDN), or MitraClip implantation. Results: IF were found in 395 of 916 patients (43.1%), with an average of 1.8 IF per patient. Classifying the IF resulted in 155 patients with minor, 171 patients with moderate, and 69 patients with major IF. The intended procedure was delayed or canceled in only 15 of 916 (1.6%) of the patients because of the presence of potential malignant IF. In patients that did undergo the intended procedure (n = 774), the presence of a moderate or major IF (23.8%) did not impact 1-year mortality compared to no or minor IF (adjusted HR 0.90, 95% CI 0.56-1.44, P value =.65). These findings were consistent among patients referred for TAVI, RDN, or MitraClip. Conclusions: IF are frequent in patients referred for cardiovascular procedures. IF did not result in a delay or cancellation of the intended procedure in the vast majority of cases, irrespective of their clinical relevance. The presence of a major or moderate IF did not significantly impact 1-year mortality

Fractional flow reserve guided percutaneous coronary intervention optimization directed by high-definition intravascular ultrasound versus standard of care

Background Post percutaneous coronary intervention (PCI) fractional flow reserve (FFR) is a significant predictor of major adverse cardiac events (MACE). The rationale for low post procedural FFR values often remains elusive based on angiographic findings alone, warranting further assessment using an FFR pullback or additional intravascular imaging. It is currently unknown if additional interventions intended to improve the PCI, decrease MACE rates. Study design The FFR REACT trial is a prospective, single-center randomized controlled trial in which 290 patients with a post PCI FFR b0.90 will be randomized (1:1) to either standard of care (no additional intervention) or intravascular ultrasound (IVUS)-directed optimization of the FFR (treatment arm). Eligible patients are those treated with angiographically successful PCI for (un)stable angina or non-ST elevation myocardial infarction (MI). Assuming 45% of patients will have a post PCI FFR b0.90, approximately 640 patients undergoing PCI will need to be enrolled. Patients with a post PCI FFR ≥ 0.90 will be enrolled in a prospective registry. The primary end point is defined as a composite of cardiac death, target vessel MI and clinically driven target vessel revascularisation (target vessel failure) at 1 year. Secondary end points will consist of individual components of the primary end point, procedural success, stent thrombosis and correlations on clinical outcome, changes in post PCI Pd/Pa and FFR and IVUS derived dimensions. All patients will be followed for 3 years. Conclusion The FFR-REACT trial is designed to explore the potential benefit of HD-IVUS-guided PCI optimization in patients with a post PCI FFR b0.90 (Dutch trial register: NTR6711). (Am Heart J 2019;213:66-72.

Clinical Characteristics and Management of Coronary Artery Perforations

BACKGROUND: Coronary artery perforation (CAP) is a potentially lethal complication of percutaneous coronary intervention. We report on the incidence, clinical characteristics, and management of iatrogenic coronary perforations based on an 11-year single-center experience. METHODS AND RESULTS: From February 9, 2005, through November 20, 2016, 150 CAP cases were identified from our percutaneous coronary intervention database of 21 212 procedures (0.71%). Mean age of CAP patients was 66±11 years, and 62.7% were male. Treated lesion type was B2/C in 94.6%, and 31.3% were chronic total occlusions. Nonworkhorse guidewires were applied in 74.3%. CAP types were Ellis type I in 2.9%, Ellis type II in 40.4%, Ellis type III in 54.8%, and Ellis type III cavity spilling in 1.9%. CAP treatment was conservative (including prolonged balloon inflation) in 73.3%. Covered stents, coiling, and fat embolization were used in 24.0%, 0.7%, and 2.0%, respectively. Pericardiocentesis for tamponade was required for 72 patients (48.0%), of whom 28 were initially unrecognized. Twelve patients (12.7%) required emergency cardiac surgery to alleviate tamponade. Periprocedural myocardial infarction occurred in 34.0%, and in-hospital all-cause mortality was 8.0%. All-cause mortality accrued to 10.7% at 30 days and 17.8% at 1 year. CONCLUSIONS: CAP is a rare complication of percutaneous coronary intervention, but morbidity and mortality are considerable. Early recognition and adequate management are of paramount importance

LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie

Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters