Explain how heartwood is different from sapwood.

2. Explain how heartwood is different from sapwood. Understanding this difference, how deep would you need to drill a hole in an 18-inch diameter maple tree to get sap for making syrup?

3. A piece of oven-dried wood weighs 3.7 pounds and has a total volume of 113.8 inches3. The specific gravity of the wood solids only is 1.5 (if you could compact the dry wood into a solid mass). The volumetric shrinkage of the wood, from green to oven-dried state, was 14.5 percent.

a. What is the oven-dried specific gravity that should be reported?

b. What should be the reported unit weight of the wood, in pounds/feet3?

c. What is the maximum moisture content of the green wood (if all wood voids were filled with water)?


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Explain why attenuation is not a big problem in PET.

Consider a 2-D object consisting of two triangle compartments, as shown in Figure P9.4. Suppose a solution containing a 511 KeV gamma ray emitting radionuclide with concentration f = 0.5….

Give the mean and the variance of the reconstructed image, mean[ˆ f(x, y)] and var[ˆ f(x, y)].

Ignoring the inverse square law and attenuation, an approximate reconstruction for SPECT imaging is given by where c˜() =  {||W()} and W() is a rectangular windowing filter that cuts off at = 0…..

Find the numerical responses in each to an event in crystal C(4, 6).

Suppose a PET detector comprises four square PMTs (arranged as a 2 by 2 matrix) and a single BGO crystal with slits made in such a way that it is….