Chestnut and litterfall production and leaf nutrient concentration in chestnut groves submitted to different soil tillage systems

The effects of several soil management systems on litterfall production (leaves, burs, chestnuts and inflorescences) and leaf nutrient concentration were studied in a 50 year-old chestnut grove, located in North-east Portugal. The experimental trial was installed in the beginning of 1996 and it was monitored for eight years. The treatments were: chisel plow (average depth 15 cm), which corresponds to the traditional tillage (MT); disc harrowing tillage, up to 7 cm depth (GD); rainfed seeded pasture, with leguminous and grasses species (PS); and no-tillage with spontaneous herbaceous vegetation (NM). Results, between 1999 and 2004, showed that the average production of litterfall (leaves, burs, chestnuts and inflorescences), was greatest in NM treatment (755 g m-2), followed by the PS (729 g m-2), GD (708 g m-2) and MT (627 g m-2) treatment, although the differences were not significant. During that period, the burs (36.7%) made the greatest contribution to total litterfall, followed by the leaves (32.5%), chestnuts (24.7%) and inflorescences (6.1%). The chestnut production was significantly lower in the MT (133 g m-2) treatment than in the NM (193 g m-2) and PS (191 g m-2). The N, P and Mg content in leaves were significantly lower in MT treatment than in the others; the K content was significantly lower in MT and PS treatments than in GD; the Ca concentration was significantly lower in MT treatment than in GD and PS. Management practices alternatives to the traditional soil tillage revealed to be more appropriated to enhance productivity of chestnut groves and to reduce production costs

Finite Element Analysis Of The Equivalent Stress Distribution In Schanz Screws During The Use Of A Femoral Fracture Distractor

To evaluate the mechanical stress and elastic deformation exercised in the thread/shaft transition of Schanz screws in assemblies with different screw anchorage distances in the entrance to the bone cortex, through the distribution and location of tension in the samples.An analysis of 3. D finite elements was performed to evaluate the distribution of the equivalent stress (triple stress state) in a Schanz screw fixed bicortically and orthogonally to a tubular bone, using two mounting patterns: (1) thread/shaft transition located 20. mm from the anchorage of the Schanz screws in the entrance to the bone cortex and (2) thread/shaft transition located 3. mm from the anchorage of the Schanz screws in entrance to the bone cortex. The simulations were performed maintaining the same direction of loading and the same distance from the force vector in relation to the center of the hypothetical bone. The load applied, its direction, and the distance to the center of the bone were constant during the simulations in order to maintain the moment of flexion equally constant. The present calculations demonstrated linear behavior during the experiment. It was found that the model with a distance of 20. mm between the Schanz screws anchorage in the entrance to the bone cortex and the thread/shaft transition reduces the risk of breakage or fatigue of the material during the application of constant static loads; in this model. the maximum forces observed were higher (350. Mpa). The distance between the Schanz screws anchorage at the entrance to the bone cortex and the smooth thread/shaft transition of the screws used in a femoral distractor during acute distraction of a fracture must be farther from the entrance to the bone cortex, allowing greater degree of elastic deformation of the material, lower mechanical stress in the thread/shaft transition, and minimized breakage or fatigue. The suggested distance is 20. mm. © 2016 Sociedade Brasileira de Ortopedia e Traumatologia

Holocene sea level fluctuations and coastal evolution in the central Algarve (southern Portugal)

In Armação de Pêra Bay, southern Portugal, environmental changes during the Holocene can be interpreted based on the morphological and sedimentological similarities between older geomorphic features (cemented beach and dune rocks) and present coastal features. Using knowledge of the present beach and dune processes, we propose a two-step model for the evolution of Armação de Pêra Bay. First, during the rapid sea level rise between about 8800 and 6600 yr cal BP, the bay changed from a positive to a negative budget littoral cell and transgressive dunes formed, favoured by drought conditions. At about 5000 yr cal BP, during a sea level maximum, beach width was less than the critical fetch and dunes stabilized and underwent cementation during the wetter Atlantic climatic event. The second phase of dune accumulation started at about 3200 yr cal BP, due to a regression of sea level during which the bay changed back to a positive budget littoral cell in which beach width was greater than the critical fetch. Currently, the beach width is less than the critical fetch, dunes are inactive, and the sedimentary budget is negative due to sediment storage in local river systems.Fundação para a Ciência e a Tecnologia. FEDER, and OE (Project POCTI/CTA/34162/2000

Body yield and quality of fresh and post-freezing filet of Nile tilapia (Oreochromis niloticus) genetic groups

Abstract The aim of this study was to evaluate the body yield and quality of fresh and post-freezing filet of male and female fish of inbred and non-inbred AquaAmérica genetic group and the hybrid between the AquaAmérica and Tilamax varieties. Forty fish (20 males and 20 females) of each genetic group were housed in four 48-m3 hapa net cages, getting 120 fish per cage. The fish were housed at 51 days of age and farmed for 269 days. Pre-slaughter weight was higher (P<0.05) in the AquaAmérica × Tilamax males (0.805±0.204 kg) than in the inbred AquaAmérica male (0.643±0.115 kg). Filet yield percentage was higher (P<0.05) in the AquaAmérica × Tilamax males (32.14±4.72%) than in the inbred AquaAmérica (28.15±2.67%) and non-inbred AquaAmérica (29.06±2.80%) males. Head and viscera yield percentages, pH, color values (L*, a* and b*), shear force, drip loss and cooking loss did not differ significantly between the genetic groups and sexes. Alterations in meat quality were observed after freezing. In conclusion, inbreeding in the AquaAmérica variety resulted in reduced slaughter weight for males; AquaAmérica × Tilamax males have a higher filet yield; and filet quality is not influenced by crossing, inbreeding, or sex, but is changed after freezing