444 research outputs found
Planar velocity & concentration measurements in a magnetic micromixer with interface front detection
No full textMixing is often a challenge in small scales and substantial research effort is focused on designing high performance micromixers. Active micromixers use various forces to enhance mixing efficiency. Among these, magnetic forces are often preferred as they are non-contact and do not require manufacturing of small moving parts in the microchannel. Laser-based diagnostic tools have great potential in providing multi-parameter information in microfluidics research on mixing. In this work, we extract velocity, concentration and interface front information from a single image pair from a magnetic micromixer undergoing labyrinthine (fingering) instability. The experiments were performed using a MicroPIV system with stroboscopic LED illumination. Velocity information from particle displacements are computed using Least Squares Matching (LSM) and compared with previously published results using Adaptive Cross Correlation (ACC). It turns out that LSM is less sensitive to image contrast; and able to extract most of the useful velocity information from the raw images compared to the processed images. This makes LSM an important global tool for PIV analysis where image pre-processing can be avoided completely, for example in industrial mixing applications. The use of image processing functions proves to be essential in multi-parameter microfluidics: Concentration measurements are performed using absorption imaging after removal of particles using a series of low-pass filters. Results for interface front detection using various other image processing functions are also presented
Three-year outcomes of A Randomized Multicentre Trial Comparing Revascularization and Optimal Medical Therapy for Chronic Total Coronary Occlusions (EuroCTO).
No full textBackground: Percutaneous coronary intervention (PCI) for chronic total coronary occlusions (CTO) improves clinical symptoms and quality of life. The longer-term safety of PCI compared to optimal medical therapy (OMT) remains uncertain.
Aims: We sought to evaluate the long-term safety of PCI for CTO in a randomised trial as compared to OMT.
Methods: A total of 396 patients with a symptomatic CTO were enrolled into a randomised, multicentre clinical trial comparing PCI and OMT. Half of the patients had a single CTO; the others had multivessel disease. Non-CTO lesions were treated prior to randomisation (2:1 ratio). During follow-up, crossover from OMT to PCI occurred in 7.3% (1 year) and 17.5% (3 years) of patients.
Results: At 3 years, the incidence of cardiovascular death or nonfatal myocardial infarction was not significantly different between the groups (OMT 3.7% vs PCI 6.2%; p=0.29). By per-protocol analysis, the difference remained non-significant (OMT 5.7% vs PCI 4.7%; p=0.67). Overall, major adverse cardiovascular events (MACE) were more frequent with OMT (OMT 21.2% vs PCI 11.2%), largely because of ischaemia-driven revascularisation. The rates of stroke or hospitalisation for bleeding were not different between the groups.
Conclusions: At 3 years there was no difference in the rate of cardiovascular death or myocardial infarction between PCI or OMT among patients with a remaining single coronary CTO. The MACE rate was higher in the OMT group due largely to ischaemia-driven revascularisation. CTO PCI appears to be a safe option for patients with a single remaining significant coronary CTO. CinicalTrials.gov: NCT01760083
Photon Bose-Einstein condensate in and out of steady state: theory and experiment
No full textThe Bose-Einstein condensate is a thermal equilibrium state characterized by a macroscopicoccupation of the ground state. Such a state exhibits spontaneous coherence at the critical temperature or particle density. In this thesis, we focus on in- and out-of steady-state properties of recently observed photon Bose-Einstein condensates. The condensed state is achieved at room temperature in a microcavity due to the small effective mass of the photon. Unlike in atom condensates, where atoms thermalize spontaneously, photons must interact with a reservoir to reach thermal equilibrium. For large reservoir sizes, the photon condensate can be regarded as an open quantum system. The photon condensate is also subjected to photon losses through the cavity. As such, condensates of light are of fundamental interest and are a promising platform for studying optical quantum gases in complex structures. In this thesis, we develop a nonequilibrium theory of photonic Bose-Einstein condensation from first principles combining the frameworks of open quantum systems and macroscopic quantum electrodynamics. This approach allows us to model the condensate in various cavity geometries and precisely evaluate the system’s influence on the condensate rates. Subsequently, we theoretically investigate the photonic condensation in a two-dimensional planar cavity at the crossover towards small mode spacing. Alongside the conventional threshold required for the transition into the condensed state, we find a second threshold emerging for smaller mode spacings, governed by system losses. Consistent with the literature, we find that the photon condensation does not occur in the limit of a free photon gas, since the critical particle number diverges. Finally, we report on the experimental measurements of the out-of-steady-state dynamics of the photon Bose-Einstein condensate in the presence of single-frequency periodic perturbation. For weak perturbations, we observe that the condensate response dynamics resembles that of a classical harmonic oscillator, in agreement with the theory. The monochromatic driving establishes an experimental platform to probe optical quantum gases and extract the system’s parameters, such as cavity decay rate and total molecule number. In addition, it allows for phase-sensitive measurements, paving the way for the demonstration of the frequency-dependent fluctuation-dissipation theorem
Intramyocardial administration of autologous bone marrow mononuclear cells in a critically ill child with dilated cardiomyopathy
No full textAbstractAlmost half of the children with symptomatic dilated cardiomyopathy receive a transplant or die within 2 years; however, cardiac stem cell transplantation has become a promising therapeutic option. The present case demonstrates for the first time, to our knowledge, the intramyocardial administration of autologous bone marrow mononuclear cells in a critically ill 4-month-old child with severe dilated cardiomyopathy. Left ventricular ejection fraction increased from 20% before stem cell transplantation to 41% at 4 months of follow-up.</jats:p
Bose-Einstein Condensation of Light in Disordered Nano Cavities at Room Temperature
No full textBose-Einstein Condensation is a macroscopic occupation of bosons in the lowest energy state. For atoms, extremely low temperatures are required to observe this phenomenon. For photons, condensation has been demonstrated at room temperature, requiring a large number of particles (N ∼ 77000) and very complicated setup. Here we study the possibility of observing BEC of light at room temperature with a much lower number of particles by leveraging disorder in a dielectric material. There is no constraint in the number of photons in the system like in the previous research. We investigate what happens to photons once they are put inside a cavity with a disorder. The analysis is carried out by using time-dependent quantum Langevin equations, complemented by a thermodynamic analysis on quantum photons. Both approaches give the same expression for the critical temperature of condensation. We demonstrate that photons in a disordered cavity with arbitrary initial statistical distribution reach thermal equilibrium and undergo a Bose-Einstein Condensation if the temperature is sufficiently reduced. In our model we demonstrate that the temperature is related to the losses of the system. At this state, photons follow Boltzmann distribution. It is demonstrated that by only varying the strength of disorder, it is possible to change the critical temperature of the phase transition, thus making condensation possible at room temperature. This work opens up the possibility to create new types of light condensate by using disorder
Management of coronary artery disease patients in Latvia compared with practice in Central-Eastern Europe and globally: analysis of the CLARIFY registry
No full textBackground and objective
Management of outpatients with stable coronary artery disease (CAD) is important in secondary prevention. The objective was to describe differences in the characteristics of CAD patients in Latvia compared with other countries.
Materials and methods
CLARIFY is an ongoing international, prospective, observational, longitudinal registry of outpatients with CAD. Data regarding treated outpatients with established CAD from the CLARIFY registry in Latvia (n = 120) were compared with those from the rest of Central-Eastern Europe (CEE) (n = 2888) and worldwide (n = 33,163).
Results
Patients in Latvia had a larger waist circumference (101 [95–109] vs. 99 [91–106] in CEE, 96.5 [88–105] cm worldwide; P = 0.023 and P < 0.001, respectively) and higher blood pressure (systolic: 138.28 ± 17.13 vs. 133.77 ± 16.47 in CEE and 130.97 ± 16.65 mm Hg worldwide, P = 0.003 and P < 0.001; diastolic: 82.98 ± 8.58 vs. 80.01 ± 9.61 in CEE and 77.22 ± 9.97 mm Hg worldwide, P < 0.001 and P < 0.001, respectively). Body mass index in Latvia did not differ significantly from that in CEE (P = 0.422), but was higher than worldwide (28.8 [26.2–32.0] vs. worldwide 27.3 [24.8–30.3] kg/m2, P < 0.001). The history of percutaneous coronary intervention was more frequent in Latvia (74.17% vs. 59.34% in CEE and 58.61% worldwide, P = 0.001 and P < 0.001, respectively). Latvian patients more frequently used aspirin (97.50% in Latvia vs. 89.75% in CEE and 87.64% worldwide, P = 0.005 and P = 0.001, respectively).
Conclusions
Latvian CAD patients are well managed in terms of aspirin use and frequency of percutaneous coronary intervention. Control of obesity and high BP is poorer and needs further improvement
A Model of Martensitic Unelasticity Accounting for the Crystal Symmetry of the Material
No full textAn approach is presented to describe the mechanical behavior of the shape memory materials. On the one hand it uses the basic concepts of the structure-analytical theory proposed by V.A.Likhachev and V.G.Malinin which are the formulation of the constitutive equations of the phase transformation and martensitic unelasticity for micro regions and the orientation averaging of micro strains to obtain the macro strain. On the other hand the averaging procedure is arranged in a way to account for the crystal symmetry of the material. Results are presented of the computer simulation of pseudoelasticity, shape memory effect and active straining of a shape memory material with a thermoelastic martensitic transformation. These are stress-strain diagrams at various temperatures, temperature dependencies of the martensitic unelastic strain. All the results show good qualitative agreement with the experiments in which dislocation plasticity does not play a significant role
Drug-eluting stent for left main coronary artery disease. The DELTA registry: a multicenter registry evaluating percutaneous coronary intervention versus coronary artery bypass grafting for left main treatment
No full textOBJECTIVES: The aim of this study was to compare, in a large all-comers registry, major adverse cardiac and cerebrovascular events (MACCE) after percutaneous coronary intervention (PCI) with first-generation drug-eluting stents (DES)
versus coronary artery bypass grafting (CABG) in unprotected left main coronary artery (ULMCA) stenosis.
BACKGROUND: Percutaneous coronary intervention with DES implantation in ULMCA has been shown to be a feasible and safe approach at midterm clinical follow-up.
METHODS: All consecutive patients with ULMCA stenosis treated by PCI with DES versus CABG were analyzed in this multinational registry. A propensity score analysis was performed to adjust for baseline differences in the overall cohort.
RESULTS: In total 2,775 patients were included: 1,874 were treated with PCI
versus 901 with CABG. At 1,295 (interquartile range: 928 to 1,713) days, there were no differences, at the adjusted analysis, in the primary composite endpoint of death, cerebrovascular accidents, and myocardial infarction (MI) (adjusted hazard ratio [HR]: 1.11; 95% confidence interval [CI]: 0.85 to 1.42; p = 0.47), mortality (adjusted HR: 1.16; 95% CI: 0.87 to 1.55; p = 0.32), or composite
endpoint of death and MI (adjusted HR: 1.25; 95% CI: 0.95 to 1.64; p = 0.11). An advantage of CABG over PCI was observed in the composite secondary endpoint of MACCE (adjusted HR: 1.64; 95% CI: 1.33 to 2.03; p < 0.0001), driven exclusively by the higher incidence of target vessel revascularization with PCI.
CONCLUSIONS: In our multinational all-comers registry, no difference was observed in the occurrence of death, cerebrovascular accidents, and MI between PCI and CABG. An advantage of CABG over PCI was observed in the incidence of MACCE, driven by the higher incidence of target vessel revascularization with PC
A case report of pulmonary vein isolation performed in a patient with polysplenia and interrupted inferior vena cava
No full textPublisher Copyright: © 2021 The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.Background: Pulmonary vein isolation (PVI) has entrenched itself as one of the main approaches for the treatment of paroxysmal symptomatic atrial fibrillation (AF). Pulmonary vein isolation prevents focal triggers from pulmonary veins from initiating AF paroxysms. As standard - PVI is performed through the inferior vena cava (IVC) approach, through the femoral vein. However, there are conditions when this approach is not appropriate or is not available. Case summary: We report a case of a 53-year-old male who was referred to Pauls Stradins Clinical University Hospital for PVI due to worsening AF. Due to the rare anatomical variant of the venous system, the standard approach to PVI could not be applied. Interrupted cava inferior did not allow for femoral vein and IVC access. We had to figure out a different path - a combination of internal jugular and subclavian veins was used. Transseptal puncture was performed under transoesophageal echocardiography (TOE) control with a puncture needle stiletto. Pulmonary veins were isolated successfully, no complications were observed, and the patient was discharged in sinus rhythm. Discussion: In some patients, PVI cannot be done through the standard IVC approach. In such cases, a different venous access must be chosen. Our patient had a rare variant of interrupted IVC and we had to use superior vena cava approach for the procedure. The difficulty of this approach is that procedure instruments are not designed for non-standard venous access; however, a combined use of TOE, general anaesthesia, and contact force-guided ablation has succeeded in isolating patients' pulmonary veins.Peer reviewe
Long-Term Outcomes of Percutaneous Coronary Interventions or Coronary Artery Bypass Grafting for Left Main Coronary Artery Disease in Octogenarians (from a Drug-Eluting stent for LefT main Artery Registry Substudy)
No full textPercutaneous coronary intervention (PCI) with drug-eluting stents is an accepted alternative to surgery for the treatment of unprotected left main coronary artery (ULMCA) disease, but the long-term outcome in elderly patients is unclear. Aim of our study was to compare the clinical outcomes of octogenarians with ULMCA disease treated either with PCI with drug-eluting stents or coronary artery bypass grafting (CABG). The primary study end point was the composite of death, cerebrovascular accident, and myocardial infarction at follow-up. A total of 304 consecutive patients with ULMCA stenosis treated with PCI or CABG and aged 80 years were selected and analyzed in a large multinational registry. Two hundred eighteen were treated with PCI and 86 with CABG. During the hospitalization, a trend toward a higher mortality rate was reported in PCI-treated patients (3.5% vs 7.3%, p = 0.32). At a median follow-up of 1,088 days, the incidence of the primary end point was similar in the 2 groups (32.6% vs 30.2%, p = 0.69). Incidence of target vessel revascularization at follow-up was higher in PCI-treated patients (10% vs 4.2%, p = 0.05). At multivariate analysis, left ventricular ejection fraction was the only independent predictor of the primary end point (hazard ratio 0.95, 95% confidence interval 0.91 to 0.98, p = 0.001). After adjustment with propensity score, the revascularization strategy was not significantly correlated to the incidence of the primary end point (hazard ratio 0.98, 95% confidence interval 0.57 to 1.71, p = 0.95). In octogenarians, no difference was observed in the occurrence of the primary end point after PCI or CABG for the treatment of ULMCA disease. However, the rate of target vessel revascularization was higher in the PCI group. (C) 2014 Elsevier Inc. All rights reserved
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