Question

MENTION THE FOUR METHODS OF TRIADS

Answer 1

Answer:

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Explanation:

The triads method is applied in validation studies of dietary intake to evaluate the correlation between three measurements (food frequency questionnaire, reference method and biomarker) and the true intake using validity coefficients (Á). The main advantage of this technique is the inclusion of the biomarker, which presents independent errors compared with those of the traditional methods. The method assumes the linearity between the three measurements and the true intake and independence between the three measurement errors. Limitations of this technique include the occurrence of Á > 1, known as "Heywood case", and the existence of negative correlations, which do not allow the calculation of Á. The objective of this review is to present the concept of the method, describe its application and examine the validation studies of dietary intake that use the triads method. We also conceptualize the "bootstrap" method, used to estimate the confidence intervals of the validity coefficients.

Food Consumption; Nutrition Surveys; Validation Studies

Answer 2

Explanation:

Johann Wolfgang Dobereiner was a chemist in the early 1800s, when the periodic table wasn't in existence, and some chemists were trying to find a type of organizational system for the known elements. Dobereiner noticed a pattern with certain elements that had similar chemical and physical properties. He called these elements triads and, thus, we have Dobereiner's Law of Triads. If you put these elements in order of their atomic masses, the average of the molar mass of the first and third elements in the triad is the molar mass of the second element. Let's look at an example.

The halogens, chlorine, bromine, and iodine, have atomic masses ≈ 35 g/mole, ≈ 80 g/mole, and ≈ 127 g/mole respectively. These values are rounded to the nearest g/mole. If we take the average of the masses of chlorine and iodine we get:

1/2(35 g/mole + 127 g/mole) = 81 g/mole, which is very close to bromine's atomic mass of 80 g/mole.