170,747 research outputs found
Too much data is never enough: a review of the mismatch between scales of water quality data collection and reporting from recent marine dredging programmes
No full textAbstract not availableLaura J. Falkenberg, Craig A. Stya
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
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
Avian magnetoreception: elaborate iron mineral containing dendrites in the upper beak seem to be a common feature of birds
No full textThe magnetic field sensors enabling birds to extract orientational information from the Earth’s magnetic field have remained enigmatic. Our previously published results from homing pigeons have made us suggest that the iron containing sensory dendrites in the inner dermal lining of the upper beak are a candidate structure for such an avian magnetometer system. Here we show that similar structures occur in two species of migratory birds (garden warbler, Sylvia borin and European robin, Erithacus rubecula) and a non-migratory bird, the domestic chicken (Gallus gallus). In all these bird species, histological data have revealed dendrites of similar shape and size, all containing iron minerals within distinct subcellular compartments of nervous terminals of the median branch of the Nervus ophthalmicus. We also used microscopic X-ray absorption spectroscopy analyses to identify the involved iron minerals to be almost completely Fe III-oxides. Magnetite (Fe II/III) may also occur in these structures, but not as a major Fe constituent. Our data suggest that this complex dendritic system in the beak is a common feature of birds, and that it may form an essential sensory basis for the evolution of at least certain types of magnetic field guided behavior
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 clinical and experimental study of the autonomous nervous system in the heart
No full textAbstract
Background: The introduction of the arterial switch operation (ASO) made it the procedure of choice
for surgical correction of transposition of the great arteries. A majority of the sympathetic nerves
innervate the heart alongside the great vessels; these are therefore likely to be damaged during the
surgical procedure; imposing new challenges and questions that need to be addressed. The main aim
for this thesis was to assess the long-term cardiac consequences on the autonomic nervous system
after surgery (paper I and II) and to create an animal model allowing for cardiac physiological studies
(paper III and IV).
Methods: Long-term follow-up in adolescents who had undergone ASO as neonates (n=17, 1 female,
mean fractional shorting 32±5%) was performed. This included sympathetic nervous system function
assessed through infusion of tritiated Norepinephrine ([3H]NE) during heart catheterisation
(n=8)(controls n=15) and blood samples analysed with high performance liquid chromatography.
Samples were obtained both before and after adenosine stimulation as a response to sympathetic
excitation. 24-hour heart rate variability (HRV)(n=15 in both groups) was measured both during the
day and night using different algorithms. Baroreflex sensitivity and QT variability index (QTVI) (n=17
in both groups) were measured in awake patients. An animal model was developed using complex
open heart surgery during cardiopulmonary bypass to mimick the arterial switch operation in piglets
8 weeks of age. The piglets surviving at least 5 to 6 weeks post-operation had follow-up of
physiological response to catecholamines and were studied in vivo and in vitro using the Langendorff
perfusion system.
Results: In both groups the specific activity of [3H]NE decreased from the artery to the coronary sinus,
but to a lesser extent in the ASO group. The extraction fraction in the ASO group was 56±10%
compared to 82±9% in the healthy subjects (p<0.001). The arterial to coronary sinus plasma
concentration of [3H] dihydroxyphenylglycol (DHPG) was significantly increased in the healthy group
(70%, p=<0.0001) but was not so in the ASO group (8%, p=0.5). The difference of endogenous DHPG
increase from the arterial to the coronary sinus was significantly smaller in the ASO group (p=0.008).
After adenosine infusion, the total body NE spillover increased in the ASO group (p=0.002), reflecting
major sympathetic activation. [3H]DHPG step-up from the artery to the coronary sinus increased 4-fold
following adenosine. HRV frequency-domain at night-time, when cardio-parasympathetic drive is
likely to be most pronounced, showed a significant decrease of normalized high frequency in the ASO
group (52±20) compared to healthy subjects (68±15)(p=0.018). Time-domain showed no statistical
difference between the two groups, neither during day-time nor night-time. Baroreflex sensitivity
and QTVI did not show significant differences between groups. The animal model resulted in 14 out
of 19 piglets surviving the mimicked ASO. Piglets operated with mimicked ASO had a significantly
higher basal heart rate both in vivo (p=0.042) and in vitro (p=0.0056).
Conclusion: A disturbed but functioning sympathetic cardiac innervation was found in the ASO
patients at long-term follow-up. The vagal tone seemed normal in terms of BRS, however, frequencydomain
analysis showed a decreased parasympathetic tone at night time in the ASO group. The
surgical challenges due to translocation of the coronary arteries and the consequences of an injured
autonomic nervous system impose risks of decreased myocardial perfusion and arrhythmias. Thus,
the present data suggest that these patients ought to have follow-up that includes autonomic
nervous system assessment
Optimization of Solid Angle and Count Rate Capability of an X-ray Detector with Backscattering Geometry
No full textWe study here an optimized geometry for an X-ray detector with hole in the center, as key component for ASCANIO: an innovative 16-channels SDD based spectrometer specifically
designed for X-ray fluorescence microscopy (XFM) imaging in synchrotron beamlines. The detector will feature a backscattering geometry with a tilted SDD layout achieving 1 sr solid
angle at 8 mm sample distance and a potential Output Count Rate higher than 20 Mcps. The 1 mm thick SDD provides 65 % absorption efficiency at 20 keV while preserving a good energy resolution better than 150 eV thanks to a dedicated cooling system and a low noise front-end electronics. In this paper, the optimization of the detector geometry, in terms of solid angle vs sample distance and maximization of the Output Count Rate introducing a tilting of the SDD units, is discussed
Segnalazione di nuove macroalghe per la Laguna di Venezia
No full textThe authors report on the occurence in the lagoon of Venice of three Rhodophyta Agardhiella subulata (C.
Agardh) Kraft & Wynne, Solieria filiformis (Kützing) Gabrielson e Dipterosiphonia rigens (Schousboe) Falkenberg
and one Chlorophyta, Tellamia sp. new for the Lagoon of Venice. A brief description for each species is provided
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