169,965 research outputs found
Counterpropagating frequency mixing with terahertz waves in diamond
No full textFrequency conversion by means of Kerr nonlinearity is one of the most common and exploited nonlinear optical processes in the UV, visible, IR, and mid-IR spectral regions. Here we show that wave mixing of an optical field and a terahertz wave can be achieved in diamond, resulting in the frequency conversion of the terahertz radiation either by sum-or difference-frequency generation. In the latter case, we show that this process is phase matched and most efficient in a counterpropagating geometry. (C) 2013 Optical Society of America</p
Short- and long-term effects of silver nanoparticles on human microvascular endothelial cells
No full textTo study the response to silver nanoparticles (Ag NP) of human microvascular endothelial cells, protagonists of angiogenesis
Analysis and comparison by gender of lactate production in young breastroke swimmers
No full textINTRODUCTION The aim of this study was to assess the differences by gender of lactate production in the 200 m breaststroke swimming, at the anaerobic threshold. Mader’s test, proposed on 1976 and modified in distance from its original version, is used to calculate the anaerobic threshold from the lactate production after a second 200 m breaststroke, in a swimming battery test. This is very useful to assess the proper swimming speed in the seasonal training planning. METHODS Twelve male (age 17.3 ± 0.2 years; height 181.2 ± 4.7 m; weight 73.2 ± 2.9 kg; best time on 200 m breaststroke 131.25 s) and female national-level swimmers (age 16.0 ± 0.2 years; height 166,4 ± 3.3 m; weight 54.2 ± 2.6 kg; best time on 200m breaststroke 143.56 s) participated in the study. Tests were performed in a 25 m swimming pool. Each swimmer twice swam a 200 m breaststroke trial: the first at 2 to 3 mmol/L (17 to 20 s slower than the personal record); the second, 30 minutes after the first, at the maximum speed. Blood lactate was measured (Lactate Pro Analyzer) three minutes after the end of each trial. Paired Student’s t test was applied to compare male and female performances and lactate production at the anaerobic threshold between. RESULTS At the anaerobic threshold, male swimmers swam the 200 m breaststroke in 145.72 ± 2.76 s, while females swimmers performed 159.12 ± 3.38 s (p < 0.01). The male swimmers’ lactate production at the anaerobic threshold was 11.0 ± 1.59 mmol/L, whereas female swimmers produced 9.3 ± 1.91 mmol/L (p < 0.05). DISCUSSION Males better performed the 200 m breaststroke swimming at the anaerobic threshold than females.. This can be easily explained by the difference in power between genders. With regard to the lactate production, female swimmers exhibited significantly lower values than males, probably due to the lower ratio between muscle mass and blood volume and to lower glycolytic activity of the skeletal muscles associated with a higher oxidative capacity of the lactate. High aerobic capacity is important for a good 200 m performance; in fact there is a high correlation between the speed corresponding to 4 mmol/L lactate production and the speed of swimmers during the 200 m race. REFERENCES Heck H, Mader A, Hess G, Mücke S, Müller R, Hollmann W. Justification of the 4-mmol/L lactate threshold. (1985) Int J Sports Med. 6(3):117-30. Janssen P. (2001). Lactate threshold training. Running, Cycling, Multisport, Rowing, X-Country Skiing. Human Kinetics, Champaign IL. Olbrecht J, Madsen O, Mader A, Liesen H, Hollmann W. (1985) Relationship between swimming velocity and lactic concentration during continuous and intermittent training exercises. Int J Sports Med. 6(2):74-7. Telford R.D., Hahn A.G., Catchpole E.A., Parker A.R., Sweetenham W.M. (1988) Postcompetition blood lactate concentration in highly ranked Australian swimmers .In: Swimming V, Ungerechts Ed., Human Kinetics, Champaign IL, 277-283
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
An unusual case of ‘delayed‘ febrile non hemolytic transfusion reaction in a thalassemia major patient with asymptomatic plasmodium falciparum infection
No full textMitomycin 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
Complete energy conversion by autoresonant three-wave mixing in nonuniform media
No full textResonant three-wave interactions appear in many fields of physics e. g. nonlinear optics, plasma physics, acoustics and hydrodynamics. A general theory of autoresonant three-wave mixing in a nonuniform medium is derived analytically and demonstrated numerically. It is shown that due to the medium nonuniformity, a stable phase-locked evolution is automatically established. For a weak nonuniformity, the efficiency of the energy conversion between the interacting waves can reach almost 100%. One of the potential applications of our theory is the design of highly-efficient optical parametric amplifiers. (C) 2013 Optical Society of Americ
Analysis of the Catalytic Splitting of H2S for H2 Production
No full textThe splitting of hydrogen sulphide to produce value-added products, namely hydrogen and elemental sulphur, represents a promising route for the treatment of H2S, a hazardous waste gas, and for a circular production of hydrogen. The decomposition reaction has been studied in a plug flow reactor on the catalyst MoS2 for temperatures ranging between 640 and 929 °C and with a H2S partial pressure of 1.27 kPa. Equilibrium conversions have been reached for residence times below 3 s and the apparent activation energy of 71.894 kJ/mol has been calculated. The catalytic decomposition on MoS2 results therefore to be an interesting pathway for the production of H2 from H2s
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