Izaias Rangel Nogueira

Diferenças entre as dimensões das fibras nos anéis de crescimento determinados no D. A. P. e em níveis diferentes do fuste de árvores adultas de Eucaliptus saligna Smith

This paper deals with the variation of fiber dimentions in growth rings taken at the breast height (B.H.) and at three aditional level of trunk height (10%, 20% and 30% of total height) of two plants of Eucalyptus saligna Smith. Statistical analyses of variance for fiber length, fiber diameter and fiber thikness in diferent growth rings at B.H., 10%, 20% and 30% of trunk height is prsented. Analysis of variance allowed the following conclusion: 1° - Significant diferences were observed for fiber dimentions mean, taken at B.H. and those taken at the levels of 10%, 20% and 30% of trink height; 2° - In any growth rings along the trunk, the fiber length means increased consistently from B.H. to the levels of 10%, 20% and 30% of trink height, however the means for fiber diameter and thikness of the wall decreace from the B.H. point to the leves of 10%, 20% and 30% of trink height; 3° - The results obtained in the present study confirm those obtained by BISSET & DASDWELL (1949) in that the maximum fiber lenght is reached at aproxmately one third of the total height of the trink and also confirm the afirmation made by RUDMAN et al (1969) that the samples taken at the B.H. level are inadequate for qualitative wood studies, specially in raltion with forest genetics investigation.

Efeito de operadores, dia de observação e tamanho de amostra e de grânulos na determinação do arredondamento de grânulos da fração areia de solos

Estudam-se, atraves da carta de comparacao visual de Krumbein, os efeitos do dia de observacao, observadores e tamanho de amostra na determinacao do arredondamento de granulos de quartzo, nas fracoes areia media, areia fina e areia muito fina de solos do arenito Botucatu, no Municipio de Piracicaba. Conclui-se que amostras de 25 granulos sao suficientes. Nao foi observado efeito estatisticamente significativo do dia de observacao. Efeito de observadores foi verificado apenas para as fracoes media e fina.

Estudo da distribuição dos pontos de máximo ou de mínimo de equações de regressão de segundo grau

When studying experiments with fertilizers from the economic point of view, it is rather common to use a quadratic regression equation Y = a X2 + b X + c, and to seek its point of maximum X = - b/2c. If the values of Y are supposed to be normally distributed, the same happens with the estimates b and c, both linear functions of the Ys. This shows that for the economical interpretation of trials with fertilizers it is important to know what is the distribution oithe ratio of two normal variates. To study the distribution of x= b/2c the statistics y1 and y2 of FISHER (1930) were used, as well as the third and fourth moments. The results obtained show that in most cases the distribution of X is far from normal.

Análise estatística de dados pluviométricos de Campinas

A statistical analysis of rainfall data collected at Campinas from 1890 to 1956 was made. In addition to total rainfall, detailed studies were made of data from January and July, the wettest and driest months of the year, respectively, and of August and October, which are intermediary. The results obtained indicated that rainfall for the same months of the year was distributed at random over the period studied and did not show any secular trend.

O regime de chuvas em Pesqueira

The authors studied the rainfall in Pesqueira (Pernambuco, Brasil) in a period of 48 years (1910 through 1957) by the method of orthogonal polynomials, degrees up to the fourth having been tried. None of them was significant, so that it seems that no trend is present. The mean observed was 679.00 mm., with standard error of the mean 205.5 mm., and a 30.3% coefficient of variation. The 95% level of probability would include annual rainfall from 263.9 up to 1094.1mm.