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Luccioni B.,National University of Tucuman | Rougier V.C.,University of Concepcion del Uruguay
Construction and Building Materials | Year: 2011

Research activities carried out during the past years concerning the use of fibre reinforced polymers (FRP) as external reinforcement of masonry walls have shown that this system considerably improves structural stability and ductility with minimum increase in the load transmitted to foundations. However, different aspects of this retrofitting system should still be analyzed. The mechanical behaviour under in-plane compression and diagonal compression of clay masonry panels reinforced or repaired with carbon fibre reinforced polymer laminates is experimentally assessed in this paper. The results show that if correct retrofitting schemes are chosen, reinforcement and repairing with fibre reinforced polymers improves masonry behaviour, increasing ductility and, in some cases, ultimate strength and even stiffness. In this way, brittle behaviour and sudden failure of unreinforced masonry can be avoided. © 2010 Elsevier Ltd. All rights reserved. Source

Iannone L.J.,University of Buenos Aires | Pinget A.D.,University of Concepcion del Uruguay | Nagabhyru P.,University of Kentucky | Schardl C.L.,University of Kentucky | De Battista J.P.,Instituto Nacional de Tecnologia Agropecuaria
Grass and Forage Science | Year: 2012

Asexual, vertically transmitted fungal endophytes of the genus Neotyphodium are considered to enhance growth, stress resistance and competitiveness of agronomic grasses, but have been suggested to have neutral or deleterious effects on wild grasses. We studied whether the associations between Bromus auleticus and their endophytes, Neotyphodium pampeanum and Neotyphodium tembladerae, are beneficial for this wild forage grass native to South America. In a greenhouse experiment, 3-month-old endophyte-infected plants (E+) showed enhanced growth relative to their endophyte-free counterparts (E-). In a one-year-long experiment in the field, E+ plants showed higher survival and regrowth rate, and produced more biomass and seeds than E- plants. Only with respect to the seed output did N. tembladerae seem to be detrimental, whereas N. pampeanum did not affect this parameter. No differences were observed with respect to the germination of seeds produced by E+ or E- plants. Loline alkaloids were detected in N. pampeanum-infected plants. Our results show that, similar to results with agronomic grasses, in wild grasses, the symbiosis with Neotyphodium species could be mutualistic. © 2012 Blackwell Publishing Ltd. Source

The present study analyzes the correlation between gymnast's relative strength and the time in seconds that the athlete can hold the swallow on rings with the idea to identify the minimum relative strength required for the proper execution of this element. In addition, a dumbbells exercise is proposed as a convenient evaluation and training method for swallow conditioning. Furthermore, gymnast body ratios were evaluated in order to achieve whether these parameters represent an advantage or disadvantage for swallow execution on rings. A Spearman's correlation test was used to compare the relative strength, height/sitting height and height/wingspan ratios versus the swallow holding time of 14 senior Elite level male gymnasts from the Argentinean team. A significant correlation (p<0.01) between the relative strength and the time in seconds that the swallow was held by the athletes was found, proving that the execution of this element on rings is explained almost in a 90% by the gymnast's relative strength. No correlation between the swallow holding time and the height/sitting height and height/wingspan ratios were found. These results could provide to gymnasts and coaches with a useful tool for easily recognize if the gymnast's physical condition is appropriate to perform a swallow on rings. Source

Piter J.C.,University of Concepcion del Uruguay
European Journal of Wood and Wood Products | Year: 2012

The present paper reports the results of an investigation regarding the study of size effects on bending strength in sawn timber of fast-growing Argentinean Eucalyptus grandis according to the criterion adopted by European standards. The results of an empirical research project with five samples containing a total of 349 specimens in usual structural sizes were studied. The analysis of the results found for the grades obtained by visually and machine strength grading of the samples according to themost important parameters showed no clear influence of either the grading model or timber quality on size effects. Results proved that the criterion adopted by European standards is suitable for considering size effects on bending strength in sawn timber of this species for practical purposes related to structural design. © Springer-Verlag 2010. Source

Piacentini R.D.,National University of Rosario | Salum G.M.,National University of Rosario | Salum G.M.,University of Concepcion del Uruguay | Fraidenraich N.,Federal University of Pernambuco | Tiba C.,Federal University of Pernambuco
Renewable Energy | Year: 2011

Extraterrestrial total solar irradiance, usually called Solar Constant, is attenuated by the atmosphere in different proportions, depending mainly on solar zenith angle and altitude of the measurement point. In this work, it is presented very high and extreme horizontal plane measurements of global solar irradiance that in some days overpassed the Solar Constant corrected by the actual Sun-Earth distance (CSC). They were obtained at sea level of the intertropical Atlantic coast, in the city of Recife, Brazil, in the period February 2008-January 2009. Extreme total solar irradiance values larger than CSC were measured during 3.4% of the days of the total registered period. This percentage increases to 7.4% for global solar irradiance within 95.1-100% of the CSC and to 15.3% within 90.1-95% of the CSC. The largest extreme total solar irradiance value, 1477 ± 30 W/m 2, was registered the 28th of March 2008 at 11:34 local time (UT - 3h). It overpassed by 7.9% the CSC value for this day (1369.4 W/m 2) and by 42.3% the estimated value of the clear sky Iqbal C radiation model (1037.7 W/m 2). The observation of extreme values should be taken into account in the study of solar radiation effects related to materials exposed to the outside, UV index and biological effects, among others. Also, the detailed knowledge of this interesting effect may contribute significantly to clarify physical aspects about the interaction of global solar radiation with the ecosystem and climate change. © 2010 Elsevier Ltd. Source

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