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Explain the role of T-cells in immune response to viral infection

When T cells bind to viral antigens presented by macrophages they undergo mitosis to form 4 distinct cell variants: Memory T cells- remain in the blood stream to initiate a faster immune response upon re-exp...
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Answered by Will S. • Biology tutor
6228 Views

Why does ice float on water?

Water has strong intermolecular hydrogen bonds that hold the water molecules close together, making it very dense. As water freezes, the hydrogen bonds move further apart as it forms a hexagonal lattice. Thi...
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Answered by Nia R. • Chemistry tutor
3636 Views

Find the centre and radius of the circle with the equation x^2 + y^2 - 8x - 6y - 20 = 0.

The general equation of a circle takes the form (x - A)^2 + (y - B)^2 = r^2 where (A,B) is the centre of the circle with radius r. Thus, we aim to rearrange the equation in the question to match this form. S...
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Answered by Thomas D. • Maths tutor
8820 Views

Find R and a such that 7*cos(x)+3*sin(x)=Rcos(x-a)

Use the cosine trig identity, cos(a-b)=cos(a)cos(b)+sin(a)sin(b) ,to write Rcos(x-a) as R(cos(x)cos(a)+sin(x)sin(a)).Now we can equate the coefficients of the sines and cosins on either side of the equation ...
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Answered by Darius Y. • Maths tutor
7221 Views

why is the number e important?

When we work with circles, one of the most popular things to pop up is pi. We know that for any circle the circumference divided by the radius gives pi, without failure always. Pi is a number that’s been fou...
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Answered by Sam V. • Maths tutor
3365 Views