Comparative analysis of the relative growth of Uca rapax (Smith) (Crustacea, Ocypodidae) from two mangroves in S\ue3o Paulo, Brazil

A study on the relative growth of two populations of Uca rapax (Smith, 1870) was performed primarily to determine the size at onset sexual maturity. The species was sampled monthly in Itamambuca (23º24'43"S and 45º00'73"W) and Ubatumirim (23º20'17.8"S and 44º53'2.2"W) mangroves. Carapace width (CW) and length (CL), abdomen width (AW), major cheliped propodus length (PL) and height (PH) for each sex, and gonopod length (GL) for males were measured with a calliper (0.01 mm). Allometric analyses were used to estimate size at maturity. The relationships that most precisely indicated the size at onset of sexual maturity were AW vs. CW, for females and PL vs. CW, for males. Males and females are mature, respectively at 15.2 and 12.1 mm CW in samples from Itamambuca and 13.5 and 11.2 mm CW in samples from Ubatumirim mangrove. Positive allometric growth of females abdominal width is likely related to the incubation process, while positively allometry growth of male's cheliped almost certainly relates to reproductive behaviour.<br>O estudo do crescimento relativo foi utilizado para determinar quais dimensões evidenciam melhor a maturidade sexual morfológica de Uca rapax (Smith, 1870). Os caranguejos foram coletados mensalmente nos manguezais de Itamambuca (23º24'43"S e 45º00'73"W) e Ubatumirim (23º20'17,8"S e 44º53'2,2"W), em período de maré baixa. Os caranguejos de ambos os sexos foram mensurados com um paquímetro (0,01 mm) quanto à largura da carapaça (LC), comprimento da carapaça (CC) e largura do abdome (LA). Nos machos mensurou-se ainda o comprimento e altura do própodo do quelípodo maior (CPQ e APQ) e comprimento do gonopódio (CG) e, no caso das fêmeas, comprimento e altura do própodo do quelípodo direito (CPQ e APQ). As análises alométricas foram utilizadas para estimar o tamanho da maturidade sexual morfológica. As relações que melhor evidenciaram o tamanho da maturidade foram LA vs. LC para fêmeas e CPQ vs. LC para machos. Machos e fêmeas estão maduros morfologicamente, respectivamente com 15,2 e 12,1 mm de LC em Itamambuca e 13,5 e 11,2 mm de LC no manguezal do rio Ubatumirim. O crescimento alomético positivo da largura do abdomen de fêmeas está relacionado com o processo de incubação, enquanto a alometria positiva do quelípodo dos machos pode estar relacionada ao comportamento reprodutivo

Modelling the Age-Hardening Precipitation by a Revised Langer and Schwartz Approach with Log-Normal Size Distribution

A new numerical modelling approach integrating the Langer and Schwartz approach and log-normal particle size distribution has been developed to depict the precipitation kinetics of age-hardening precipitates in Al alloys. The modelling framework has been implemented to predict the precipitation behavior of the key secondary phases in 6xxx and 7xxx Al alloys subjected to artificial aging. The simulation results are in good agreement with the available experimental data in terms of precipitate number density, radius, and volume fraction. The initial shape parameter of the log-normal size distribution entering the modeling framework turns to play an important role in affecting the later-stage evolution of precipitation. It is revealed that the evolution of size distribution is not significant when a small shape parameter is adopted in the modelling, while an initial large shape parameter will cause substantial broadening of the particle size distribution during aging. Regardless of the magnitude of shape parameter, a broadening of the particle size distribution as predicted by the present model is in agreement with experimental observations. It is also shown that large shape parameter will accelerate the coarsening rate at later aging stage, which induces fast decreasing of number density and increased growth rate of mean/critical radius. A comparison to the Euler-like multi-class approach demonstrates that the integration of more realistic log-normal distribution and Langer and Schwartz model make the present modelling faster and equivalently accurate in precipitation prediction