Recruitment and growth variation of Ophionereis reticulata (Echinodermata: Ophiuroidea)

Two growth patterns are recognized in shallow-water ophiuroids: (I) slow growth and early reproductive maturity over a long life span and (2) rapid growth with a short life span. For species with the first pattern, both growth and recruitment would reflect a reproductive pattern with long periods of resting and spawning concentrated in certain months of the year. To evaluate this hypothesis, the recruitment, population dynamics, and growth of the intertidal brittle star Ophionereis reticulata were analyzed from January 2001 to December 2002 at the Baleciro Isthmus on the southeast coast of Brazil. The species shows an annual gametogenic cycle with spawning taking place in summer. Densities varied from 0.46 to 9.46 individuals m(-2). Density variations and seawater temperature were not significantly correlated. The population structure of O. reticulata was polymodal, with at least four co-occurring cohorts. Recruitment events were recorded in March 2001, October 2001, January 2002, and September 2002. As indicated by the asymptote size (D(infinity)=11.47 mm +/- 1.46), growth constant (K=0.42 year(-1)+/- 0.12), and oscillation index (C=0.97 +/- 0.51), the growth pattern of O. reticulata seems to be based on high survivorship of juveniles and adults, where sexual maturity is reached at a small size with rapid growth in the first 2 years of life. A low level of settlement is to be expected based on these data; however, there must be a minimum successful survivorship and development for juveniles and adults. Another explanation for the lack of small individuals (disc diameter <1.0 mm) could be that recruitment is located in a different area and a post-settlement migration might be involved in the maintenance of the population.

Height-diameter relationships of tropical Atlantic moist forest trees in southeastern Brazil

Site-specific height-diameter models may be used to improve biomass estimates for forest inventories where only diameter at breast height (DBH) measurements are available. In this study, we fit height-diameter models for vegetation types of a tropical Atlantic forest using field measurements of height across plots along an altitudinal gradient. To fit height-diameter models, we sampled trees by DBH class and measured tree height within 13 one-hectare permanent plots established at four altitude classes. To select the best model we tested the performance of 11 height-diameter models using the Akaike Information Criterion (AIC). The Weibull and Chapman-Richards height-diameter models performed better than other models, and regional site-specific models performed better than the general model. In addition, there is a slight variation of height-diameter relationships across the altitudinal gradient and an extensive difference in the stature between the Atlantic and Amazon forests. The results showed the effect of altitude on tree height estimates and emphasize the need for altitude-specific models that produce more accurate results than a general model that encompasses all altitudes. To improve biomass estimation, the development of regional height-diameter models that estimate tree height using a subset of randomly sampled trees presents an approach to supplement surveys where only diameter has been measured.

Sulcus anatomy and diameter in pseudophakic eyes and correlation with biometric data: Evaluation with a 50 MHz ultrasound biomicroscope

PURPOSE: To evaluate the sulcus anatomy and possible correlations between sulcus diameter and white-to-white (WTW) diameter in pseudophakic eyes, data that may be important in the stability of add-on intraocular lenses (IOLs). SETTING: University Eye Hospital, Tuebingen, Germany. DESIGN: Case series. METHODS: In pseudophakic eyes, the axial length (AL) and horizontal WTW were measured by the IOLMaster device. Cross-sectional images were obtained with a 50 MHz ultrasound biomicroscope on the 4 meridians: vertical, horizontal (180 degrees), temporal oblique, and nasal oblique. Sulcus-to-sulcus (STS), angle-to-angle (ATA), and sclera-to-sclera (ScTSc) diameters were measured. The IOL optic diameter (6.0 mm) served as a control. To test reliability, optic measurements were repeated 5 times in a subset of eyes. RESULTS: The vertical ATA and STS diameters were statistically significantly larger than the horizontal diameter (P=.0328 and P=.0216, respectively). There was no statistically significant difference in ScTSc diameters. A weak correlation was found between WTW and horizontal ATA (r = 0.5766, P<.0001) and between WTW and horizontal STS (r = 0.5040, P=.0002). No correlation was found between WTW and horizontal ScTSc (r = 0.2217, P=.1217). CONCLUSIONS: The sulcus anatomy had a vertical oval shape with the vertical meridian being the largest, but it also had variation in the direction of the largest meridian. The WTW measurements showed a weak correlation with STS. In pseudophakic eyes, Soemmerring ring or a bulky haptic may affect the ciliary sulcus anatomy.

Steel fibre reinforced concrete pipes. Part 2: numerical model to simulate the crushing test

This paper is part of an extensive work about the technological development, experimental analysis and numerical modeling of steel fibre reinforced concrete pipes. The first part ("Steel fibre reinforced concrete pipes. Part 1: technological analysis of the mechanical behavior") dealt with the technological development of the experimental campaign, the test procedure and the discussion of the structural behavior obtained for each of the dosages of fibre used. This second part deals with the aspects of numerical modeling. In this respect, a numerical model called MAP, which simulates the behavior of fibre reinforced concrete pipes with medium-low range diameters, is introduced. The bases of the numerical model are also mentioned. Subsequently, the experimental results are contrasted with those produced by the numerical model, obtaining excellent correlations. It was possible to conclude that the numerical model is a useful tool for the design of this type of pipes, which represents an important step forward to establish the structural fibres as reinforcement for concrete pipes. Finally, the design for the optimal amount of fibres for a pipe with a diameter of 400 mm is presented as an illustrating example with strategic interest.