182,938 research outputs found
Ragout-jet FTIR spectroscopy of cluster isomerism and cluster dynamics: from carboxylic acid dimers to N2O nanoparticles
No full textDirect absorption supersonic jet Fourier transform spectroscopy provides a panoramic view of the dynamics of molecular clusters over the entire IR spectral range. The new and generally applicable ragout-jet technique compensates for the sensitivity limits inherent in the incoherent FTIR approach by the use of synchronized giant gas pulses expanding into a large vacuum buffer. A modification based on fragmented interferograms is proposed and demonstrated, by which the spectral resolution can be extended to the limit of the available FTIR spectrometer. The power of the method is illustrated for two classes of compounds. For acetic acid and its isotopomers, the supersonic jet spectra of dimers and oligomers are investigated for the first time, concentrating on the very complex OH/CH stretching domain and on the more regular C=O/C-O stretching range. Issues of cluster isomerism, hydrogen exchange tunneling, anharmonic resonances, intermolecular Franck-Condon sequences, methyl group substitution and cluster coating with argon are explored. For the more weakly interacting nitrous oxide, stretching fundamentals and combination bands of clusters in the 1-3 nm range are studied as a function of composition. Surface vibrations are investigated in detail and modeled quantum mechanically. The semiempirical AM1 approach is found to provide a remarkably accurate description of the cluster structure, energetics and dynamics
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
The Roots of NEP Satire: The Case of Teffi and Zoshchenko
No full textHaber, Edythe C.. (2007). The Roots of NEP Satire: The Case of Teffi and Zoshchenko. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/186866
Competing hydrogen bond topologies in 2-fluoroethanol dimer
No full textIsolated 2-fluoroethanol exists predominantly as a pair of enantiomeric all-gauche conformations, which are stabilized by an intramolecular O-H center dot center dot center dot F interaction. Its most stable OH center dot center dot center dot OH hydrogen-bonded dimers differ in their relative monomer configuration and in their network of weak intermolecular interactions involving the electronegative fluorine atoms. OH-stretching FTIR spectra of supersonic jet expansions using He as a carrier gas reveal four dimer isomers. Only two isomers survive upon Ar admixture. Exploratory quantum chemical calculations confirm that the two surviving conformations involve insertion of the OH group of one monomer into the intramolecular O-H center dot center dot center dot F interaction of the other. The two unstable conformations consist of more loosely associated monomers. Chiral recognition leads to different OH stretching wavenumbers for homo- and heteroconfigurational dimers, but both are formed in similar quantities in the jet expansion. (c) 2005 Elsevier B.V. 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
Epigomphus wagneri Haber 2017, new species
No full textEpigomphus wagneri new species Figures 1 d; 3c; 4c; 5e, f; 9c; 10c; 12. Specimens examined. Holotype male: COSTA RICA, Provincia Puntarenas, Monteverde, Río Guacimal (10.27, - 84.82), 725 m, 27 June 2010, leg. WAH (INBIO; INB 0004319188). Etymology. This species is named for David Wagner, a brilliant entomologist, naturalist, and gomphid enthusiast, who roused my passion for the Odonata, and who has proven to be a trusted friend and travel companion on many expeditions in Costa Rica and Ecuador. Description. Male holotype. Head with maximum width 7.0 mm (Fig. 1 d), dark brown above; labrum with a pair of large pale spots near lateral margins; base of mandible and gena pale; top of frons with a pale stripe covering anterior 2/3, indented in middle but unbroken; antennae all dark; eyes blue in life; lateral ocelli slightly closer to eye margin than to center line; postocellar area with only a shallow central depression; posterior margin of occiput with a rounded ridge, the ridge bearing a pair of collapsed small tubercles on dorsum; rear margin of ridge weakly indented in dorsal view; underside of head pale in anterior half, shading to dark in posterior half. Thorax dark brown with a pattern of pale markings similar to E. subobtusus (Fig. 1 d; 9c). Prothorax fore lobe with pale anterior margin; midlobe with a pair of contiguous pale spots in center and a pale spot on each side; hind lobe dark; propleuron pale on lower margin. Pterothorax with mesepisternum bearing two complete pale antehumeral stripes, both separate from collar stripe; mesepimeron with a complete pale stripe in center; metepisternum with a broad stripe that narrows posteriorly and ends almost separated from a posterior spot; metepimeron mostly pale bordered above by brown and with a thick central brown stripe about 2/3 as long as the segment; mesinfraepisternum with a pale spot at upper end and a larger pale triangle at lower end; metinfraepisternum all pale; metasternum pale; underside pale, unmarked. Legs. Fore and mid legs with femur mostly black, shading to brown at base and to lighter brown on posterior side; interior side of foreleg pale; hind femur light brown, shading to dark brown at apex. Wings hyaline (Fig. 3 c) with brown to black venation; basal subcostal veins present; cubito-anal crossveins 3 in all wings; FW Ax 18, 17 with 6, 6 thickened; Px 13, 14; HW Ax 13, 14 with 6, 7 thickened; Px 13, 13; pterostigma dark red-brown, opaque, 3.3 mm in FW, 3.6 mm in HW; crossveins above supratriangle between arculus and point of branching of RP 6, 6 in FW, 4, 4 in HW; posttriangular cell space in FW with two rows of cells for 9, 8 cells. Abdomen dark brown with pale markings; S1–4 with a pale dorsal mid line (wider on S1–2); S1–2 mostly pale on sides, S3 with a pale lateral stripe 3/4 length of segment; S4–6 with a basal pale triangle on sides; S7 2 /3 pale; S8–10 and appendages unmarked; S10 with a low dorsal hump barely grooved on mid line. Abdominal appendages. Cercus (Fig. 4 c; 10c) 2.2 mm long, shaped as in E. subobtusus; distal transverse edge with 7 small teeth; epiproct forming a thick fused plate with short branches and a short, broad U-shaped sinus; in lateral view a hump at mid length where branches curve downward, then directed rearward to an abrupt dull acute apex; in ventral view the sinus indented at two levels (Fig. 4 c). Secondary genitalia. Vesica spermalis (Fig. 5 e, f) similar to other Costa Rican species in having a ventral protuberance on the dorsal lobe, but differs from others in that the horns are pointed vertically as in E. camelus (Fig. 11 g) and E. quadracies (Calvert 1903) (Fig. 11 h), while those of other Costa Rican species are directed rearward. Measurements (mm). Total length 47; abdomen 36; FW 33; HW 31, maximum width 8.0. Female. Unknown. Diagnosis. Thoracic pattern and cercus shape as in E. subobtusus, epiproct shorter than cercus with short, weakly differentiated branches, and the sinus between the branches shallow and broadly U-shaped. Natural history. E. wagneri is known only from the male holotype. The specimen was a mature male that was perched at 11:00 hr, apparently on a territory, on a dead stick projecting from a shallow, partly shaded pool in a spring stream at the interface of forest and pasture. No larvae of E. wagneri were found during numerous visits to the area spanning seven years.Published as part of Haber, William A., 2017, Three new species of Epigomphus (Odonata: Gomphidae) from Costa Rica, pp. 73-94 in Zootaxa 4282 (1) on pages 88-89, DOI: 10.11646/zootaxa.4282.1.4, http://zenodo.org/record/81844
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