170,434 research outputs found
Interaction of Fe+ with the C-60 surface: A study about the feasibility of endohedral doping
No full textThe feasibility of endohedral iron doping of C-60 is studied using a mass selected ion beam to create an Fe+ beam with variable energy (60-380 eV, 1.2x10(-3) C) which is directed at a C-60 thin film. The surface is characterized by x-ray photoelectron spectroscopy, and oxidation of the samples is used to discriminate between Fe@C-60 and carbides. The fullerene cages are damaged during the irradiation, and participate in direct Fe-C bond formation. The reaction with oxygen indicates the absence of sizable amount of Fe@C-60. Comparison with reference samples composed of iron and damaged fullerene layers (by Ar+ irradiation) supports this interpretation. The experiment serves as a model study for the investigation of different metal-fullerene combinations. (C) 2004 American Institute of Physics
Reply from Authors re: Arthur L. Burnett. Erection Rehabilitation After Radical Prostatectomy: Definite Purpose, Indefinite Strategy. Eur Urol 2014; 65: 597-8 Although Erection Rehabilitation After Prostatectomy Remains Indefinite, the Most Effective Treatment, the Earliest Recovery, and the Preservation of Erectile Function Remain a Definite Goal
No full textGoing 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
mmunohistological studies on neoplasms of female and male Onchocerca volvulus: Filarial origin and absence of Wolbachia from tumor cells
No full textUp to 5% of untreated female Onchocerca volvulus filariae develop potentially fatal pleomorphic neoplasms, whose incidence is increased following ivermectin treatment. We studied the occurrence of 8 filarial proteins and of Wolbachia endobacteria in the tumor cells. Onchocercomas from patients, untreated and treated with antibiotics and anthelminthics, were examined by immunohistology. Neoplasms were diagnosed in 112 of 3587 female and in 2 of 1570 male O. volvulus. The following proteins and other compounds of O. volvulus were expressed in the cells of the neoplasms: glutathione S-transferase 1, lysosomal aspartic protease, cAMP-dependent protein kinase, alpha-enolase, aspartate aminotransferase, ankyrin E1, tropomyosin, heat shock protein 60, transforming growth factor-beta, and prostaglandin E2. These findings prove the filarial origin of the neoplasms and confirm the pleomorphism of the tumor cells. Signs indicating malignancy of the neoplasms are described. Wolbachia were observed in the hypodermis, oocytes, and embryos of tumor-harbouring filariae using antibodies against Wolbachia surface protein, Wolbachia HtrA-type serine protease, and Wolbachia aspartate aminotransferase. In contrast, Wolbachia were not found in the cells of the neoplasms. Further, neoplasm-containing worms were not observed after more than 10 months after the start of sufficient treatment with doxycycline or doxycycline plus ivermectin
Tunga penetrans : molecular identification of Wolbachia endobacteria and their recognition by antibodies against proteins of endobacteria from filarial parasites
No full textIn search of Wolbachia in human parasites, Wolbachia were identified in the sand flea Tunga penetrans. PCR and DNA sequencing of the bacterial 16S rDNA, the ftsZ cell division protein, the Wolbachia surface protein (wsp) and the Wolbachia aspartate aminotransferase genes revealed a high similarity to the respective sequences of endosymbionts of filarial nematodes. Using these sequences a phylogenetic tree was generated, that indicates a close relationship between Wolbachia from T. penetrans and from filarial parasites, but possibly as a member of a new supergroup. Ultrastructural studies showed that Wolbachia are abundant in the ovaries of neosomic fleas, whereas other, smaller and morphologically distinct, bacteria were observed in the lumen of the intestine. Wolbachia were labeled by immunohistology and immunogold electron microscopy using polyclonal antibodies against wsp of Drosophila, of the filarial parasite Dirofilaria immitis, or against hsp 60 from Yersinia enterocolitica. These results show that as in filariasis, humans with tungiasis are exposed to Wolbachia. Furthermore, antisera raised against proteins of Wolbachia from arthropods or from filarial parasites can be immunologically cross-reactive
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
Motoneurons of twitch and nontwitch extraocular muscle fibers in the abducens, trochlear, and oculomotor nuclei of monkeys
No full textEye muscle fibers can be divided into two categories: nontwitch, multiply innervated muscle fibers (MIFs), and twitch, singly innervated muscle fibers (SIFs). We investigated the location of motoneurons supplying SIFs and MIFs in the six extraocular muscles of monkeys. Injections of retrograde tracers into eye muscles were placed either centrally, within the central SIF endplate zone; in an intermediate zone, outside the SIF endplate zone, targeting MIF endplates along the length of muscle fiber; or distally, into the myotendinous junction containing palisade endings. Central injections labeled large motoneurons within the abducens, trochlear or oculomotor nucleus, and smaller motoneurons lying mainly around the periphery of the motor nuclei. Intermediate injections labeled some large motoneurons within the motor nuclei but also labeled many peripheral motoneurons. Distal injections labeled small and medium-large peripheral neurons strongly and almost exclusively. The peripheral neurons labeled from the lateral rectus muscle surround the medial half of the abducens nucleus: from superior oblique, they form a cap over the dorsal trochlear nucleus; from inferior oblique and superior rectus, they are scattered bilaterally around the midline, between the oculomotor nucleus; from both medial and inferior rectus, they lie mainly in the C-group, on the dorsomedial border of oculomotor nucleus. In the medial rectus distal injections, a "C-group extension" extended up to the Edinger-Westphal nucleus and labeled dendrites within the supraoculomotor area. We conclude that large motoneurons within the motor nuclei innervate twitch fibers, whereas smaller motoneurons around the periphery innervate nontwitch, MIF fibers. The peripheral subgroups also contain medium-large neurons which may be associated with the palisade endings of global MIFs. The role of MIFs in eye movements is unclear, but the concept of a final common pathway must now be reconsidered. J. Comp. Neurol. 438:318-335, 2001. (C) 2001 Wiley-Liss, Inc
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
Pressure dependence of the solubility of Ar and Kr in melts of the system SiO2-NaAlSi2O6
No full textThe solubilities of Ar and Kr in supercooled melts in the system SiO2-NaAlSi2O6 have been studied at temperatures of 1200 degrees C (SiO2), 1000 and 750 degrees C (NaAlSi3O8), and 800 degrees C (NaAlSi2O6) at pressures from 200 to 6000 bar. Gas sorption experiments were performed in an internally heated pressure vessel, and noble gas concentrations in quenched samples were analyzed by absolute analytical techniques [gas chromatography (GC), and thermogravimetry (TG), gravimetry]. Comparison of the results from this study with other absolute techniques (Rutherford-backscattering, mass spectrometry) is possible for silica and exhibit excellent agreement. This agreement leads us to conclude that our silica glasses with an Ar concentration of 1.02 wt% and a Kr concentration of 0.54 wt% are suitable as standard materials. Solubility increases linearly with increasing pressure for all three compositions. In SiO2 the solubility of Ar and Kr increases with pressure with nearly parallel slopes, whereas Ar and Kr exhibit diverging slopes in NaAlSi3O8 and NaAlSi2O6. The linear relationship between fugacity and dissolved gas below 2-3 kbar, indicates that Henry's law constants (in units of 10(6) bar) for Ar in SiO2, NaAlSi3O8, and NaAlSi2O6 are 0.94, 3.15, and 5.71, respectively, and for Kr are 1.38, 5.69, and 9.28, respectively. The experimental results can be modeled by two alternative thermodynamic approaches. First, assuming mixing of noble gases with the network of the melt, partial molar volumes (in cm(3)/mol) can be calculated in SiO2, NaAlSi3O8, and NaAlSi2O6 for Ar as 25.9 +/- 1.3, 21.1 +/-. 1.6, and 21.1 +/- 0.7, respectively and for Kr as 24.3 +/- 1.8, 27.6 +/- 0.8, and 24.7 +/- 0.9, respectively. Second, assuming the volume change upon solution to be zero, a Langmuir Isotherm can be applied yielding saturation levels M (in units of 10(20) sites/cm(3) melt) in SiO2, NaAlSi3O8, and NaAlSi2O6 for Ar as 3.82 +/- 0.6, 1.33 +/- 0.2, and 0.72 +/- 0.08, respectively and for Kr as 3.49 +/- 0.7, 0.56 +/- 0.05, and 0.42 +/- 0.06, respectively. Highest solubility is observed in all three melts for Ar. Solubility decreases with increasing substitution of Si4+ by Na+ + Al3+. Th, dependence of solubility on composition supports the structural model for melts along the join SiO2-NaAlSi2O6, based on a stuffed tridymite-like structure
Diffusivity and solubility of He in garnet: An exploratory study using nuclear reaction analysis
No full textWe have used the nuclear reaction He-3(d,p)He-4 in an exploratory study of the diffusivity and solubility of He in the mineral garnet. The garnet samples analyzed were single crystals which had been loaded with He-3 at 7000 bar pressure and temperatures of 900, 950 and 1000 degrees C. From the He-3 depth profiles measured we could deduce diffusion coefficients and solubility values. For the diffusivity the Arrhenius parameters D-0 = 7.5 x 10(9) cm(2)/s and E-a = 500 kJ/mol were found. An estimate of 11.5 at ppm was obtained for the apparent solubility, which comprises volume solubility and dislocation solubility, and an upper limit of 3 at ppm for the volume solubility. Furthermore, out-diffusion of He at room temperature occurring faster than to be expected from the high-temperature diffusivity was observed. The results are compared to those of a preceding study in which a bulk technique for measuring He-4 had been used. It can be concluded that the NRA technique is well suited to the problem in question. (c) 2005 Elsevier B.V. All rights reserved
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