1,363 research outputs found

    Atomic excitation during recollision-free ultrafast multi-electron tunnel ionization

    Full text link
    Modern intense ultrafast pulsed lasers generate an electric field of sufficient strength to permit tunnel ionization of the valence electrons in atoms. This process is usually treated as a rapid succession of isolated events, in which the states of the remaining electrons are neglected. Such electronic interactions are predicted to be weak, the exception being recollision excitation and ionization caused by linearly-polarized radiation. In contrast, it has recently been suggested that intense field ionization may be accompanied by a two-stage `shake-up' reaction. Here we report a unique combination of experimental techniques that enables us to accurately measure the tunnel ionization probability for argon exposed to 50 femtosecond laser pulses. Most significantly for the current study, this measurement is independent of the optical focal geometry, equivalent to a homogenous electric field. Furthermore, circularly-polarized radiation negates recollision. The present measurements indicate that tunnel ionization results in simultaneous excitation of one or more remaining electrons through shake-up. From an atomic physics standpoint, it may be possible to induce ionization from specific states, and will influence the development of coherent attosecond XUV radiation sources. Such pulses have vital scientific and economic potential in areas such as high-resolution imaging of in-vivo cells and nanoscale XUV lithography.Comment: 17 pages, 4 figures, original format as accepted by Nature Physic

    Prediction of ventricular arrhythmia in phospholamban p.Arg14del mutation carriers–reaching the frontiers of individual risk prediction

    Get PDF
    Aims: This study aims to improve risk stratification for primary prevention implantable cardioverter defibrillator (ICD) implantation by developing a new mutation-specific prediction model for malignant ventricular arrhythmia (VA) in phospholamban (PLN) p.Arg14del mutation carriers. The proposed model is compared to an existing PLN risk model. / Methods and results: Data were collected from PLN p.Arg14del mutation carriers with no history of malignant VA at baseline, identified between 2009 and 2020. Malignant VA was defined as sustained VA, appropriate ICD intervention, or (aborted) sudden cardiac death. A prediction model was developed using Cox regression. The study cohort consisted of 679 PLN p.Arg14del mutation carriers, with a minority of index patients (17%) and male sex (43%), and a median age of 42 years [interquartile range (IQR) 27-55]. During a median follow-up of 4.3 years (IQR 1.7-7.4), 72 (10.6%) carriers experienced malignant VA. Significant predictors were left ventricular ejection fraction, premature ventricular contraction count/24 h, amount of negative T waves, and presence of low-voltage electrocardiogram. The multivariable model had an excellent discriminative ability {C-statistic 0.83 [95% confidence interval (CI) 0.78-0.88]}. Applying the existing PLN risk model to the complete cohort yielded a C-statistic of 0.68 (95% CI 0.61-0.75). / Conclusion: This new mutation-specific prediction model for individual VA risk in PLN p.Arg14del mutation carriers is superior to the existing PLN risk model, suggesting that risk prediction using mutation-specific phenotypic features can improve accuracy compared to a more generic approach

    Peritoneal dialysis prescription in children: bedside principles for optimal practice

    Get PDF
    There is no unique optimal peritoneal dialysis prescription for all children, although the goals of ultrafiltration and blood purification are universal. In turn, a better understanding of the physiology of the peritoneal membrane, as a dynamic dialysis membrane with an exchange surface area recruitment capacity and unique permeability characteristics, results in the transition from an empirical prescription process based on clinical experience alone to the potential for a personalized prescription with individually adapted fill volumes and dwell times. In all cases, the prescribed exchange fill volume should be scaled for body surface area (ml/m2), and volume enhancement should be conducted based on clinical tolerance and intraperitoneal pressure measurements (IPP; cmH2O). The exchange dwell times should be determined individually and adapted to the needs of the patient, with particular attention to phosphate clearance and ultrafiltration capacity. The evolution of residual kidney function and the availability of new, more physiologic, peritoneal dialysis fluids (PDFs) also influence the prescription process. An understanding of all of these principles is integral to the provision of clinically optimal PD

    Efficacy of serology driven “test and treat strategy” for eradication of H. pylori in patients with rheumatic disease in the Netherlands

    Get PDF
    The treatment of choice of H. pylori infections is a 7-day triple-therapy with a proton pump inhibitor (PPI) plus amoxicillin and either clarithromycin or metronidazole, depending on local antibiotic resistance rates. The data on efficacy of eradication therapy in a group of rheumatology patients on long-term NSAID therapy are reported here. This study was part of a nationwide, multicenter RCT that took place in 2000–2002 in the Netherlands. Patients who tested positive for H. pylori IgG antibodies were included and randomly assigned to either eradication PPI-triple therapy or placebo. After completion, follow-up at 3 months was done by endoscopy and biopsies were sent for culture and histology. In the eradication group 13% (20/152, 95% CI 9–20%) and in the placebo group 79% (123/155, 95% CI 72–85%) of the patients were H. pylori positive by histology or culture. H. pylori was successfully eradicated in 91% of the patients who were fully compliant to therapy, compared to 50% of those who were not (difference of 41%; 95% CI 18–63%). Resistance percentages found in isolates of the placebo group were: 4% to clarithromycin, 19% to metronidazole, 1% to amoxicillin and 2% to tetracycline

    Serum Levels of Advanced Glycation Endproducts and Other Markers of Protein Damage in Early Diabetic Nephropathy in Type 1 Diabetes

    Get PDF
    Objective To determine the role of markers of plasma protein damage by glycation, oxidation and nitration in microalbuminuria onset or subsequent decline of glomerular filtration rate (termed “early GFR decline”) in patients with type 1 diabetes. Methods From the 1st Joslin Kidney Study, we selected 30 patients with longstanding normoalbuminuria and 55 patients with new onset microalbuminuria. Patients with microalbuminuria had 8–12 years follow-up during which 33 had stable GFR and 22 early GFR decline. Mean baseline GFRCYSTATIN C was similar between the three groups. Glycation, oxidation and nitration markers were measured in protein and ultrafiltrate at baseline by liquid chromatography-tandem mass spectrometry using the most reliable methods currently available. Results Though none were significantly different between patients with microalbuminuria with stable or early GFR decline, levels of 6 protein damage adduct residues of plasma protein and 4 related free adducts of plasma ultrafiltrate were significantly different in patients with microalbuminuria compared to normoalbuminuria controls. Three protein damage adduct residues were decreased and 3 increased in microalbuminuria while 3 free adducts were decreased and one increased in microalbuminuria. The most profound differences were of N-formylkynurenine (NFK) protein adduct residue and Nω-carboxymethylarginine (CMA) free adduct in which levels were markedly lower in microalbuminuria (P<0.001 for both). Conclusions Complex processes influence levels of plasma protein damage and related proteolysis product free adducts in type 1 diabetes and microalbuminuria. The effects observed point to the possibility that patients who have efficient mechanisms of disposal of damaged proteins might be at an increased risk of developing microalbuminuria but not early renal function decline. The findings support the concept that the mechanisms responsible for microalbuminuria may differ from the mechanisms involved in the initiation of early renal function decline

    Predictive factors for overactive bladder symptoms after pelvic organ prolapse surgery

    Get PDF
    Contains fulltext : 89696.pdf (publisher's version ) (Closed access)INTRODUCTION AND HYPOTHESIS: This study focussed on the factors which predict the presence of symptoms of overactive bladder (OAB) after surgery for pelvic organ prolapse (POP). METHODS: Consecutive women who underwent POP surgery with or without the use of vaginal mesh materials in the years 2004-2007 were included. Assessments were made preoperatively and at follow-up, including physical examination (POP-Q) and standardised questionnaires (IIQ, UDI and DDI). RESULTS: Five hundred and five patients were included with a median follow-up of 12.7 (6-35) months. Bothersome OAB symptoms decreased after POP surgery. De novo bothersome OAB symptoms appeared in 5-6% of the women. Frequency and urgency were more likely to improve as compared with urge incontinence and nocturia. The best predictor for the absence of postoperative symptoms was the absence of preoperative bothersome OAB symptoms. CONCLUSION: The absence of bothersome OAB symptoms preoperatively was the best predictor for the absence of postoperative symptoms.1 september 201

    Quantitative Histomorphometry of the Healthy Peritoneum

    Get PDF
    The peritoneum plays an essential role in preventing abdominal frictions and adhesions and can be utilized as a dialysis membrane. Its physiological ultrastructure, however, has not yet been studied systematically. 106 standardized peritoneal and 69 omental specimens were obtained from 107 patients (0.1-60 years) undergoing surgery for disease not affecting the peritoneum for automated quantitative histomorphometry and immunohistochemistry. The mesothelial cell layer morphology and protein expression pattern is similar across all age groups. Infants below one year have a thinner submesothelium; inflammation, profibrotic activity and mesothelial cell translocation is largely absent in all age groups. Peritoneal blood capillaries, lymphatics and nerve fibers locate in three distinct submesothelial layers. Blood vessel density and endothelial surface area follow a U-shaped curve with highest values in infants below one year and lowest values in children aged 7-12 years. Lymphatic vessel density is much lower, and again highest in infants. Omental blood capillary density correlates with parietal peritoneal findings, whereas only few lymphatic vessels are present. The healthy peritoneum exhibits major thus far unknown particularities, pertaining to functionally relevant structures, and subject to substantial changes with age. The reference ranges established here provide a framework for future histomorphometric analyses and peritoneal transport modeling approaches. © 2016, EDP Science. All rights reserved
    corecore