Up-conversion In Rare-earth Doped Micro-particles Applied To New Emissive 2d Dislays

Up-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two photon absorption in which a strong absorbing constituent absorbs two low energy photons and transfers this energy to another constituent which emits visible light. Some of the UC emitters\u27 most appealing characteristics for displays are: a wide color gamut with very saturated colors, very high brightness operation without damage to the emitters, long lifetimes and efficiencies comparable to those of existing technologies. Other advantages include simplicity of fabrication, versatility of operating modes, and the potential for greatly reduced display weight and depth. Thanks to recent advances in material science and diode laser technology at the excitation wavelength, UC selected materials can be very efficient visible emitters. However, optimal UC efficiencies strongly depend on chosing proper operating conditions. In this thesis, we studied the conditions required for optimization. We demonstrated that high efficiency UC depends on high pump irradiance, low temperature and low scattering. With this understanding we can predict how to optimally use UC emitters in a wide range of applications. In particular, we showed how our very efficient UC emitters can be applied to make full color displays and very efficient white light sources

Assessment of Ventricular Pacing in the Setting of an Institutional Improvement Program: Insights into Physiological Pacing

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Rapid and MR-Independent IK1 activation by aldosterone during ischemia-reperfusion

In ST elevation myocardial infarction (STEMI) context, clinical studies have shown the deleterious effect of high aldosterone levels on ventricular arrhythmia occurrence and cardiac mortality. Previous in vitro reports showed that during ischemia-reperfusion, aldosterone modulates K+ currents involved in the holding of the resting membrane potential (RMP). The aim of this study was to assess the electrophysiological impact of aldosterone on IK1 current during myocardial ischemia-reperfusion. We used an in vitro model of “border zone” using right rabbit ventricle and standard microelectrode technique followed by cell-attached recordings from freshly isolated rabbit ventricular cardiomyocytes. In microelectrode experiments, aldosterone (10 and 100 nmol/L, n=7 respectively) increased the action potential duration (APD) dispersion at 90% between ischemic and normoxic zones (from 95±4ms to 116±6 ms and 127±5 ms respectively, P<0.05) and reperfusion-induced sustained premature ventricular contractions occurrence (from 2/12 to 5/7 preparations, P<0.05). Conversely, potassium canrenoate 100 nmol/L and RU 28318 1 μmol/l alone did not affect AP parameters and premature ventricular contractions occurrence (except Vmax which was decreased by potassium canrenoate during simulated-ischemia). Furthermore, aldosterone induced a RMP hyperpolarization, evoking an implication of a K+ current involved in the holding of the RMP. Cell-attached recordings showed that aldosterone 10 nmol/L quickly activated (within 6.2±0.4 min) a 30 pS K+-selective current, inward rectifier, with pharmacological and biophysical properties consistent with the IK1 current (NPo =1.9±0.4 in control vs NPo=3.0±0.4, n=10, P<0.05). These deleterious effects persisted in presence of RU 28318, a specific MR antagonist, and were successfully prevented by potassium canrenoate, a non specific MR antagonist, in both microelectrode and patch-clamp recordings, thus indicating a MR-independent IK1 activation. In this ischemia-reperfusion context, aldosterone induced rapid and MR-independent deleterious effects including an arrhythmia substrate (increased APD90 dispersion) and triggered activities (increased premature ventricular contractions occurrence on reperfusion) possibly related to direct IK1 activation

Numerical model of the temperature dependence of the up-conversion efficiency of fluoride crystals codoped with ytterbium and thulium

We review the role of temperature on the up-conversion efficiency of materials that are good candidates to be used as the three primary-color emitters in optically written displays. A rate equation model is given for the blue emitting material that includes temperature-dependent coefficients for energy transfer and cross relaxation. Increased temperature leads to decreased up-conversion efficiency. The effect of pumping conditions on heating the emitting material is illustrated and explained. Steps to reduce the temperature rise when pumping up-conversion materials are described

Confirmatory testing in primary aldosteronism: extensive medication switching is not needed in all patients

Objective: Confirmatory testing of suspected primary aldosteronism (PA) requires an extensive medication switch that can be difficult for patients with severe complicated hypertension and/or refractory hypokalemia. For this reason, we investigated the effect of chronic antihypertensive medication on confirmatory testing results. To allow the results to be interpreted, the reproducibility of confirmatory testing was also evaluated. Design and methods: The study enrolled 114 individuals with suspected PA who underwent two confirmatory tests. The patients were divided into two groups. In Group A, both tests were performed on the guidelines-recommended therapy, i.e. not interfering with the renin–angiotensin–aldosterone system. In Group B, the first test was performed on chronic therapy with the exclusion of thiazides, loop diuretics, and aldosterone antagonists; and the second test was performed on guidelines-recommended therapy. Saline infusion, preceded by oral sodium loading, was used to suppress aldosterone secretion. Results: Agreement in the interpretation of the two confirmatory tests was observed in 84 and 66 % of patients in Groups A and B respectively. For all 20 individuals in Group A who ever had end-test serum aldosterone levels R240 pmol/l, aldosterone was concordantly nonsuppressible during the other test. Similarly, for all 16 individuals in Group B who had end-test serum aldosterone levels R240 pmol/l on modified chronic therapy, aldosterone remained nonsuppressible with guidelines-recommended therapy. Conclusion: Confirmatory testing performed while the patient is on chronic therapy without diuretics and aldosterone antagonists can confirm the diagnosis of PA, provided serum aldosterone remains markedly elevated at the end of saline infusion. European Journal of Endocrinology 166 679–68

Comparison of outcomes in patients with abandoned versus extracted implantable cardioverter defibrillator leads

SummaryBackgroundDespite the increased number of implantable cardioverter defibrillator (ICD) recipients and the frequent need for device upgrading and/or occurrence of lead malfunction, the optimal approach to managing abandoned leads remains debated. Aims To determine the rate and type of complications related to either abandoned or extracted ICD leads. Methods Patients with abandoned or extracted leads were identified retrospectively. Patient medical records were reviewed to assess long-term lead or device malfunction, defibrillation test values before and after lead abandonment or extraction, and appropriateness of delivered shocks and subsequent surgical procedures related to devices or leads. Results A total of 58 ICD patients with 47 extracted and 34 abandoned leads were identified. After a mean follow-up of 3.2 ± 2.6 years, the defibrillation test was not affected by either abandoned or extracted leads (23.4 ± 6.6 J vs 25.4 ± 4.9 J, respectively; P = 0.24). There were no differences in the number of ICD-related surgical procedures after extracting versus abandoning leads (22% vs 12%, respectively; P = 0.3) or in the thromboembolic event rate (7.7% vs 6.3%; P = 0.83). During follow-up, no differences in the occurrence of major complications or appropriate/inappropriate shocks were observed between patients with or without abandoned leads. Conclusion We observed no difference in rates of immediate or medium-term complications between extracting versus abandoning leads. Lead abandonment remains an alternative and safe option when extraction does not appear mandatory according to the age of the leads or experience of the operating centre

Apical aneurism and myocardial bridging in a patient with hypertrophic cardiomyopathy: Association or consequence of the myocardial bridging?

The identification of high-risk patients with hypertrophic cardiomyopathy (HC) for primary prevention of sudden cardiac death (SCD) remains a challenging issue, since major risk factors sometimes lack specificity. We report the case of a patient with HC and association of apical aneurysm and myocardial bridging who had been initially not implanted because she had only one major risk factor. She subsequently experienced a sustained ventricular tachycardia that finally motivated the implantation. We conclude that it is never an easy decision to implant a preventive implantable cardioverter-defibrillator (ICD). Nevertheless, additional criteria for a better selection of patients who would benefit from an ICD implant are certainly useful

Transradial versus transfemoral approach for percutaneous coronary intervention in cardiogenic shock: A radial-first centre experience and meta-analysis of published studies

SummaryBackgroundThe transradial approach for percutaneous coronary intervention (PCI) is associated with a better outcome in myocardial infarction (MI), but patients with cardiogenic shock (CS) were excluded from most trials.AimsTo compare outcomes of PCI for MI-related CS via the transradial versus transfemoral approach.MethodsA prospective cohort of 101 consecutive patients admitted for PCI for MI-related CS were treated via the transradial (n=74) or transfemoral (n=27) approach. Cox proportional hazards models adjusted for prespecified variables and a propensity score for approach were used to compare mortality, death/MI/stroke and bleeding between the two groups. A complementary meta-analysis of six studies was also performed.ResultsPatients in the transradial group were younger (P=0.039), more often male (P=0.002) and had lower GRACE and CRUSADE scores (P=0.003 and 0.001, respectively) and rates of cardiac arrest before PCI (P=0.009) and mechanical ventilation (P=0.006). Rates of PCI success were similar. At a mean follow-up of 756 days, death occurred in 40 (54.1%) patients in the transradial group versus 22 (81.5%) in the transfemoral group (adjusted hazard ratio [HR]: 0.49, 95% confidence interval [CI] 0.28–0.84; P=0.012). The transradial approach was associated with reduced rates of death/MI/stroke (adjusted HR: 0.53, 95%CI: 0.31–0.91; P=0.02) and major bleeding (adjusted HR: 0.34, 95%CI: 0.13–0.87; P=0.02). The meta-analysis confirmed the benefit of transradial access in terms of mortality (relative risk [RR]: 0.63, 95%CI: 0.58–0.68) and major bleeding (RR: 0.43, 95%CI: 0.32–0.59).ConclusionThe transradial approach in the setting of PCI for ischaemic CS is associated with a dramatic reduction in mortality, ischaemic and bleeding events, and should be preferred to the transfemoral approach in radial expert centres