39 research outputs found
Geometric phases in astigmatic optical modes of arbitrary order
The transverse spatial structure of a paraxial beam of light is fully
characterized by a set of parameters that vary only slowly under free
propagation. They specify bosonic ladder operators that connect modes of
different order, in analogy to the ladder operators connecting
harmonic-oscillator wave functions. The parameter spaces underlying sets of
higher-order modes are isomorphic to the parameter space of the ladder
operators. We study the geometry of this space and the geometric phase that
arises from it. This phase constitutes the ultimate generalization of the Gouy
phase in paraxial wave optics. It reduces to the ordinary Gouy phase and the
geometric phase of non-astigmatic optical modes with orbital angular momentum
states in limiting cases. We briefly discuss the well-known analogy between
geometric phases and the Aharonov-Bohm effect, which provides some
complementary insights in the geometric nature and origin of the generalized
Gouy phase shift. Our method also applies to the quantum-mechanical description
of wave packets. It allows for obtaining complete sets of normalized solutions
of the Schr\"odinger equation. Cyclic transformations of such wave packets give
rise to a phase shift, which has a geometric interpretation in terms of the
other degrees of freedom involved.Comment: final versio
Long-range strain correlations in sheared colloidal glasses
Glasses behave as solids on experimental time scales due to their slow
relaxation. Growing dynamic length scales due to cooperative motion of
particles are believed to be central to this slow response. For quiescent
glasses, however, the size of the cooperatively rearranging regions has never
been observed to exceed a few particle diameters, and the observation of
long-range correlations that are signatures of an elastic solid has remained
elusive. Here, we provide direct experimental evidence of long-range
correlations during the deformation of a dense colloidal glass. By imposing an
external stress, we force structural rearrangements that make the glass flow,
and we identify long-range correlations in the fluctuations of microscopic
strain, and elucidate their scaling and spatial symmetry. The applied shear
induces a transition from homogeneous to inhomogeneous flow at a critical shear
rate, and we investigate the role of strain correlations in this transition.Comment: 11 pages, 3 figures. Accepted for publication in PR
Rotational stabilization and destabilization of an optical cavity
We investigate the effects of rotation about the axis of an astigmatic
two-mirror cavity on its optical properties. This simple geometry is the first
example of an optical system that can be destabilized and, more surprisingly,
stabilized by rotation. As such, it has some similarity with both the Paul trap
and the gyroscope. We illustrate the effects of rotational (de)stabilization of
a cavity in terms of the spatial structure and orbital angular momentum of its
modes.Comment: 5 pages, 3 figures. Accepted for publication in Physical Review
Rotationally induced vortices in optical cavity modes
We show that vortices appear in the modes of an astigmatic optical cavity
when it is put into rotation about its optical axis. We study the properties of
these vortices and discuss numerical results for a specific realization of such
a set-up. Our method is exact up to first order in the time-dependent paraxial
approximation and involves bosonic ladder operators in the spirit of the
quantum-mechanical harmonic oscillator.Comment: 8 pages, 5 figures. Accepted for publication in a special issue
(singular optics 2008) of Journal of Optics A: Pure and Applied Optic
Conservation laws and symmetry transformations of the electromagnetic field with sources
Quantum Matter and Optic
TCT-342 Risk and Consequences of Periprocedural Myocardial Infarction Following Off-Label Use of Second Generation Drug-Eluting Stents: Two-Year Follow-up in the TWENTE Trial
Comparison of eligible non-enrolled patients and the randomised TWENTE trial population treated with Resolute and XIENCE V drug-eluting stents
Aims: The TWENTE trial recently enrolled more than 80% of all eligible patients, who were randomised to zotarolimus-eluting Resolute or everolimus-eluting XIENCE V stents. In the present study, we investigated whether eligible, non-enrolled patients differed from the randomised TWENTE trial population in baseline characteristics and one-year outcome. Methods and results: Characteristics of 1,709 eligible patients were analysed. Independent external adjudication of clinical events was likewise performed for non-enrolled (n=318) and randomised patients (n=1,391). Non-enrolled and randomised patients did not differ in gender distribution, diabetes mellitus, and clinical presentation, but differed significantly in age and cardiovascular history. Nevertheless, clinical outcome after one year did not differ in the primary composite endpoint target-vessel failure (TVF; 9.8% vs. 8.1%; p=0.34), and its components cardiac death (1.6% vs. 1.2%; p=0.61), target vessel-related myocardial infarction (4.7% vs. 4.6%; p=0.92), and target-vessel revascularisation (3.8% vs. 3.0%; p=0.48). Previous bypass surgery predicted TVF in non-enrolled patients (p=0.001); removal of these patients resulted in identical TVF rates for non-enrolled and randomised patients (7.3% vs. 7.3%; p=0.99). Conclusions: Despite some differences in baseline characteristics, non-enrolled and randomised patients did not differ in one-year outcome, which was favourable for both populations and may be related to the drug-eluting stents used
Clinical Outcome Following Stringent Discontinuation of Dual Antiplatelet Therapy After 12 Months in Real-World Patients Treated With Second-Generation Zotarolimus-Eluting Resolute and Everolimus-Eluting Xience V Stents : 2-Year Follow-Up of the Randomized TWENTE Trial
Objectives
The aim of this study was to assess the safety and efficacy of the implantation of Resolute zotarolimus-eluting stents (ZES) (Medtronic Inc., Santa Rosa, California) and Xience V everolimus-eluting stents (EES) (Abbott Vascular, Santa Clara, California) following strict discontinuation of dual antiplatelet therapy (DAPT) after 12 months.
Background
Only limited long-term follow-up data are available from head-to-head comparisons of second-generation drug-eluting stents.
Methods
The randomized TWENTE (The Real-World Endeavor Resolute Versus Xience V Drug-Eluting Stent Study in Twente) trial is an investigator-initiated study performed in a population with many complex patients and lesions and only limited exclusion criteria. Patients were randomly assigned 1:1 to ZES (n = 697) or EES (n = 694).
Results
Two-year follow-up information was available on all patients. The rate of continuation of DAPT beyond 12 months was very low (5.4%). The primary endpoint of target vessel failure, a composite of cardiac death, target vessel–related myocardial infarction, and target vessel revascularization, did not differ between ZES and EES (10.8% vs. 11.6, p = 0.65), despite fewer target lesion revascularizations in patients with EES (2.6% vs. 4.9%, p = 0.03). The patient-oriented composite endpoint was similar (16.4% vs. 17.1%, p = 0.75). Two-year rates of definite or probable stent thrombosis were 1.2% and 1.4%, respectively (p = 0.63). Very late definite or probable stent thrombosis occurred only in 2 patients in each study arm (0.3% vs. 0.3%, p = 1.00).
Conclusions
After 2 years of follow-up and stringent discontinuation of DAPT beyond 12 months, Resolute ZES and Xience V EES showed similar results in terms of safety and efficacy for treating patients with a majority of complex lesions and off-label indications for drug-eluting stents. (The Real-World Endeavor Resolute Versus Xience V Drug-Eluting Stent Study in Twent
TCT-47 Two-Year Clinical Outcome of the TWENTE Trial, a Randomized Controlled Trial Comparing Second-Generation Zotarolimus-Eluting Resolute Stents Versus Everolimus-Eluting Xience V Stents in Real-World Patients
Background: In the prospective, randomized TWENTE trial, the zotarolimus-eluting Resolute stent was at 1 year follow-up non-inferior to the everolimus-eluting Xience V stent for the primary endpoint target vessel failure. This composite endpoint consisted of cardiac death, clinically indicated target vessel revascularization, or target vessel-related myocardial infarction (MI). So far, few long-term data of prospective head-to-head comparisons between both DES have been reported. Methods: Patients requiring percutaneous coronary interventions (PCI) with DES implantation at Thoraxcentrum Twente in Enschede were randomization between Resolute (Medtronic Vascular, Santa Rosa, CA, USA) and Xience V (Abbott Vascular, Santa Clara, CA, USA) in a 1:1 fashion. Inclusion of all coronary or bypass graft lesions and all clinical settings was permitted except for primary PCI (i.e. acute ST-elevation myocardial infarction (STEMI) was an exclusion criterion). Both external monitoring and clinical event adjudication were performed by an independent external contract research organization (Cardialysis, Rotterdam, the Netherlands). Two year clinical follow-up was performed as indicated in the study protocol. Results: A total of 1,391 patients were enrolled in the TWENTE trial between June 2008 and August 2010. The study population comprised 21.6% diabetics with a vast majority of complex lesions and “off-label” indications for drug-eluting stents (77.4%). Patients presented with either stable angina (48.5%) or unstable angina/Non-STEMI (51.5%). Demographics, baseline angiographic and procedural data, and 2-year clinical follow-up data will be presented. This includes the primary endpoint of the study: Target vessel failure (TVF) at 2 year follow-up. Secondary endpoints include the individual components of the primary endpoint and the incidence of very late stent thrombosis. In addition, results of subgroup analyses will be reported. Conclusions: Results of pre-specified analyses of 2-year clinical outcome of the TWENTE trial will be presented at TCT 2012
Increased platelet reactivity is associated with circulating platelet-monocyte complexes and macrophages in human atherosclerotic plaques
Objective: Platelet reactivity, platelet binding to monocytes and monocyte infiltration play a detrimental role in atherosclerotic plaque progression. We investigated whether platelet reactivity was associated with levels of circulating platelet-monocyte complexes (PMCs) and macrophages in human atherosclerotic carotid plaques. Methods: Platelet reactivity was determined by measuring platelet P-selectin expression after platelet stimulation with increasing concentrations of adenosine diphosphate (ADP), in two independent cohorts: the Circulating Cells cohort (n = 244) and the Athero-Express cohort (n = 91). Levels of PMCs were assessed by flow cytometry in blood samples of patients who were scheduled for percutaneous coronary intervention (Circulating Cells cohort). Monocyte infiltration was semi-quantitatively determined by histological examination of atherosclerotic carotid plaques collected during carotid endarterectomy (Athero-Express cohort). Results: We found increased platelet reactivity in patients with high PMCs as compared to patients with low PMCs (median (interquartile range): 4153 (1585-11267) area under the curve (AUC) vs. 9633 (3580-21565) AUC, P<0.001). Also, we observed increased pl