169,985 research outputs found
CuAu, a hexagonal two-dimensional metal
No full textGrowth of two-dimensional metals has eluded materials scientists since the discovery of the atomically thin graphene and other covalently bound 2D materials. Here, we report a two-atom-thick hexagonal copper-gold alloy, grown through thermal evaporation on freestanding graphene and hexagonal boron nitride. The structures are imaged at atomic resolution with scanning transmission electron microscopy and further characterized with spectroscopic techniques. While the 2D structures are stable over months in vacuum, electron irradiation in the microscope provides sufficient energy to cause a phase transformation - atoms are released from their lattice sites with the gold atoms eventually forming face-centered cubic nanoclusters on top of 2D regions during observation. The presence of copper in the alloy enhances sticking of gold to the substrate, which has clear implications for creating atomically thin electrodes for applications utilizing 2D materials. Its practically infinite surface-to-bulk ratio also makes the 2D CuAu particularly interesting for catalysis applications
Electron-Beam-Induced Adatom-Vacancy-Complexes in Mono- and Bilayer Phosphorene
No full textPhosphorene, a puckered 2D allotrope of phosphorus, has sparked considerable interest in recent years due to its potential especially for optoelectronic applications with its layer-number-dependant direct band gap and strongly bound excitons. However, detailed experimentalcharacterization of its intrinsic defects as well as its defect creation characteristics under electron irradiation are scarce. Here, the creation and stability of a variety of defect configurations under 60 kV electron irradiation in mono- and bilayer phosphorene are reported including the first experimental reports of stable adatom-vacancy-complexes. Displacement cross section measurements in bilayer phosphorene yield a value of 7.7 ± 1.4 barn with an estimated lifetime of adatom-vacancy-complexes of 19.9 ± 0.7 s, while some are stable for up to 68 s under continuous electron irradiation. Surprisingly, ab initio-based simulations indicate that the complexes should readily recombine, even in structures strained by up to 3%. The presented results will help to improve the understanding of the wide variety of defects in phosphorene, their creation, and their stability, which may enable new pathways for defect engineered phosphorene devices
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Laparoscopic pelvic lymphadenectomy in 32 pregnant patients with cervical cancer: Rationale, description of the technique, and outcome
No full textObjective: Individualized treatment of pregnant patients with cervical cancer is mandatory; hence, information on nodal status is pivotal to allow awaiting strategy in early-stage disease. We aimed to verify the oncological safety and surgical reproducibility of a standardized laparoscopic pelvic lymphadenectomy in pregnant patients with cervical cancer. Methods: We standardized laparoscopic pelvic lymphadenectomy during the first and second term of gestation in 32 patients with cervical cancer since 1999. According to gestational week (GW) of less than 16 GWs or more than 16 GWs, 2 different techniques were used. Results: The International Federation of Gynecology and Obstetrics stages were IA in 10 patients, IB1 in 17 patients, IB2 in 4 patients, and IIA in 1 patient. Mean (SD) GW was 17.5 (5.1) weeks. Mean (SD) operative time was 105.4 (29) minutes. Mean (SD) blood loss was 5.3 (10.2) mL. There were no conversion to laparotomy and no intraoperative complications. A median number of 14 pelvic lymph nodes (range, 8-57) were harvested. Median hospital stay was 6 days. Median follow-up is 42.5 months (range, 17-164). Four patients had lymph node metastases. Five patients interrupted their pregnancy. Fourteen patients were given neoadjuvant platin-based systemic therapy. All patients are alive and disease free. All children born through cesarean delivery at a mean (SD) 34 (1.9) GWs are well and show normal clinical neurological development. Conclusions: To the best of our knowledge, this is the largest series so far reported on laparoscopic pelvic lymphadenectomy during pregnancy. This procedure is safe and associated with good oncological and obstetrical outcomes. Copyright © 2014 by IGCS and ESGO
Laparoscopic lymph node dissection should be performed before fertility preserving treatment of patients with cervical cancer
No full textObjective: The aim of this study is to assess our results of treatment of women with stage I cervical cancer > 2 cm in diameter seeking fertility preservation. Treatment consisted of Laparoscopic Pelvic and Paraaortic Lymphadenectomy (LPPLND), and when no nodal metastasis was detected, neoadjuvant chemotherapy (NACT) followed by radical vaginal trachelectomy (RVT). Patients with positive lymph nodes underwent primary chemoradiation. Methods: A cohort of women younger than 40 years of age with stage I disease > 2 cm who underwent LPPLND and either NACT and RVT or chemoradiation. Oncological outcome was evaluated prospectively. Results: Eighteen women were eligible for this study. Twelve (67%) women were diagnosed with metastasis in one or more pelvic and/or paraaortic lymph nodes, and thus received primary chemoradiation. After a mean follow-up of 25.5 months, three out of these 12 women (25%) developed a recurrence. Six women (33%) underwent NACT and RVT. Three patients experienced complete response to NACT and three patients showed more than 50% tumor size reduction. After a mean follow-up of 30.6 months all six women are free of recurrence. One patient delivered a healthy infant. Conclusions: Staging LPPLND allows separating patients in high or low recurrence risk groups. NACT and RVT seem to be safe for women with completely staged stage I cervical cancer > 2 cm in diameter, whereas even after primary chemoradiation, patients with positive lymph nodes experienced recurrence. Therefore, selection of patients with stage I cervical carcinoma > 2 cm, eligible for fertility preservation should include histopathologic evaluation of lymph node status before any further treatment. © 2012 Elsevier Inc. All rights reserved
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Fertility outcome after radical vaginal trachelectomy: A prospective study of 212 patients
No full textObjective: For treatment in patients with early-stage cervical cancer, radical vaginal trachelectomy (RVT) as a fertility-preserving surgery can be put on a par with radical hysterectomy as to oncologic safety. Our aim was to investigate the fertility concerns and outcome. Methods: Prospective collection of fertility data of patients treated with RVT. The data were collected on personal communication, by telephone, or e-mail correspondence. Descriptive statistical analysis was performed. Results: Between March 2005 and April 2010, 212 patients were followed up after RVT. Only 76 patients (35.9%) were seeking parenthood currently. Sixty pregnancies occurred in 50 women. Five patients (8.3%) had first-trimester miscarriage, 3 had second-trimester miscarriage (5.0%), 2 patients decided for pregnancy termination (3.3%), and 1 patient (1.7%) had an ectopic pregnancy. Three women (5.0%) delivered prematurely before 28th weeks of gestation, 15 (25.0%) delivered between 28 and 36 weeks, and 27 women (45.0%) reached full term. Four pregnancies are ongoing. Conclusions: Preservation of childbearing function is a great advantage for patients with early-stage cervical cancer. Many patients do not seek parenthood immediately. We see no impairment of fertility and have solid data on pregnancy outcome. Premature labor is the main problem in pregnancy after RVT. Copyright copy; 2011 by IGCS and ESGO
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
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