Controlled size reduction of rare earth doped nanoparticles for optical quantum technologies

Rare earth doped nanoparticles with sub-wavelength size can be coupled to optical micro- or nano-cavities to enable efficient single ion readout and control, a key requirement for quantum processors and high-fidelity single-ion quantum memories. However, producing small nanoparticles with good dispersion and exploitable optical coherence properties, another key aspect for these applications, is highly challenging by most synthesis and nano-fabrication methods. We report here on the wet chemical etching of Eu³⁺:Y₂O₃ nanoparticles and demonstrate that a controlled size reduction down to 150 nm, well below the wavelength of interest, 580 nm, can be achieved. The etching mechanism is found to proceed by reaction with grain boundaries and isolated grains, based on obtained particles size, morphology and polycrystalline structure. Furthermore, this method allows maintaining long optical coherence lifetimes (T₂): the 12.5 μs and 9.3 μs values obtained for 430 nm initial particles and 150 nm etched particles respectively, revealing a broadening of only 10 kHz after etching. These values are the longest T₂ values reported for any nanoparticles, opening the way to new rare-earth based nanoscale quantum technologies.

Chemical etching is a promising way to synthesize RE:Y₂O₃ nanoparticles with controlled size and long coherence lifetimes, opening the way to optical micro/nano-cavities coupling and efficient nanoscale quantum memories and processors.     

Electrogram recording and analyzing techniques to optimize selection of target sites for ablation of cardiac arrhythmias

The extracellular electrogram is caused by transmembrane currents that flow into extracellular space during propagation of the electrical impulse. Electrograms are usually recorded in unipolar or bipolar mode that have different characteristics, but provide complementary information. Both recording modes have specific advantages, but also suffer from disadvantages. Techniques to circumvent some of the weaknesses are reviewed. The origin of remote and fractionated deflections and their relation with electrode characteristics are discussed. Epicardial and endocardial sites of origin and breakthrough sites as well as the effect of fatty tissue on extracellular electrograms are presented. Induction of tachycardia to assess the arrhythmogenic area is not always possible because of hemodynamic instability of the patient. Techniques to assess sites with high reentry vulnerability without induction of arrhythmias are outlined such as activation‐repolarization mapping and decremental stimulation. Pitfalls of substrate mapping and techniques to avoid them as omnipolar mapping and characterization of complex electrograms by entropy are presented. Technical aspects that influence electrogram morphology as electrode size, filtering, contact force, and catheter position are delineated. Data from the various publications suggest that a combination of unipolar and bipolar electrogram analysis techniques is helpful to optimize determination of target sites for ablation.     

Experience coercion,post‐traumatic stress,and satisfaction with treatment associated with different coercive measures during psychiatric hospitalization

Coercive measures are frequently used in psychiatric hospitalization. However, there are few studies that analyse perceived coercion, post‐traumatic stress, and subjective satisfaction with the hospitalization treatment associated with different types of coercive measures. The sample consisted of 111 patients admitted to two psychiatric units and divided into three groups based on the measure applied: involuntary medication (N = 41), mechanical restraint (N = 32), and combined measures (mechanical restraint and involuntary medication; N = 38). The outcome variables were perceived coercion evaluated with the Coercion Experience Scale (CES), post‐traumatic stress evaluated with the Davidson Trauma Scale (DTS), and satisfaction with the treatment evaluated with the Client's Assessment of Treatment (CAT). The results found higher levels of perceived coercion associated with the use of mechanical restraint (P = 0.002) and combined measures (P < 0.001) in comparison with involuntary medication. Additionally, in relation to post‐traumatic stress, mechanical restraint (P = 0.013) and combined measures (P = 0.004) were more stressful compared to involuntary medication. Finally, the use of combined measures was associated with lower satisfaction with inpatient psychiatric treatment compared to the use of involuntary medication (P = 0.006). The following recommendation would be consistent with the results found: if a patient does not specify a preference for some type of measure, involuntary medication could be used and mechanical restraint avoided, especially when used in combination with involuntary medication.     

Side‐On Nematic Liquid Crystal Dendrimers Based on PAMAM and PPI as Dendritic Scaffolds: Synthesis and Characterization

The design, synthesis, and investigation of two series of side‐on dendrimers displaying nematic liquid crystal behavior at room temperature are described. The dendritic structures are derived from poly(amidoamine) (PAMAM‐(NH₂)_n) or poly(propylene imine) dendrimers (PPI‐(NH₂)_n) (with n = 4, 8, 16, 32, and 64) containing lateral attached mesogenic units in the periphery. The materials are characterized by ¹H, ¹³C nuclear magnetic resonance (NMR) spectroscopy, matrix‐assisted laser desorption/ionization‐mass (MALDI‐TOF MS) spectrometry, differential scanning calorimetry (DSC), polarized optical microscopy (POM), and x‐ray diffraction spectroscopy. All dendrimers exhibit nematic mesophase behavior at room temperature. Conoscopic studies reveal that the nematic phase is uniaxial. The relationship between the structure of the two dendrimer series and the mesomorphic behavior is discussed.

     

Prognosis of acute myocardial infarction in the thrombolytic era: medical evaluation is still valuable

BACKGROUND: Modern and sophisticated technology for the management of myocardial infarction has progressively devalued medical evaluation. HYPOTHESIS: This study was undertaken to assess the importance of the findings of medical evaluation at hospital presentation, in patients with acute myocardial infarction. METHODS: Data from 590 thrombolytic-treated myocardial infarction patients were analyzed. The patients were grouped according to their clinical status on arrival at hospital. A modified Forrester classification--subset II was divided according to the absence (IIa) or presence (IIb) of symptoms--was applied. Short- (14 days) and long-term (up to 10 years) survival was analyzed and 19 independent variables were included in the multivariate models. RESULTS: Short-term survival was 95.6% for subset I, 83.3% for subset IIa, 60% for subset IIb, 54.6% for subset III, and 34.8% for subset IV (P<0.001). By multiple regression analysis, lower clinical subsets (P<0.001), fewer coronary arteries with disease (P=0.006), younger age (P=0.014), absence of reinfarction (P=0.034), longer interval between streptokinase infusion and coronary arteriography (P=0.016), and higher left ventricular ejection fraction (P=0.037) demonstrated significant and independent correlation with short-term survival. Long-term survival for the total population was 71+/-3.6% for subset I, 54.4+/-8.5% for subset IIa, 20.8+/-9.4% for subset IIb, 54.5+/-15% for subset III, and 0% for subset IV (P<0.001). Using Cox regression analysis, lower clinical subsets (P<0.001), younger age (P<0.001), higher global left ventricular ejection fraction (P<0.001), and fewer coronary arteries with disease (P=0.021) correlated independently and significantly with long-term survival. When excluding data from patients who died before the short-term follow-up (n=532), lower clinical subsets remained an important predictor of long-term survival (P<0.001). CONCLUSION: Clinical classification at hospital presentation is a powerful predictor of short- and long-term survival post-myocardial infarction.