____ modulation, which is commonly employed in contemporary modems, uses each signal change to represent 4 bits.?
A. ?Quadrature amplitude
B. ?Quadrature frequency
C. ?Quadrature noise
D. ?Quadrature phase
Answer: A
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Consider the ER diagram shown in Figure 7.21 for part of a BANK database. Each bank can have multiple branches, and each branch can have multiple accounts and loans.
(a) List the strong (nonweak) entity types in the ER diagram.
(b) Is there a weak entity type? If so, give its name, its partial key, and its identifying relationship.
(c) What constraints do the partial key and the identifying relationship of the weak entity type specify in this diagram?
(d) List the names of all relationship types, and specify the (min,max) constraint on each participation of an entity type in a relationship type. Justify your choices.
(e) List concisely the user requirements that led to this ER schema design.
(f) Suppose that every customer must have at least one account but is restricted
to at most two loans at a time, and that a bank branch cannot have more than
1000 loans. How does this show up on the (min,max) constraints?