A good DBMS incorporates the services of a to organize the disk files in an optimal way, in order to minimize access time to the records.

Consider a slotted aloha system, where the time slot equals the fixed duration of each packet. assume that there are 4 stations a, b,c, d sharing the medium. (a) stations a, b,c, d receive one packet each from higher layers at times 1.3, 1.5, 2.6,5.7 respectively. show which transmissions take place when, according to the slottedaloha protocol; describe all transmissions until all four packets have been successful. when needed, each station has access to the following sequence of random number, provided by a random number generator and drawn uniformly between 0 and 1: (1) station a draws numbers: 0.31, 0.27, 0.78, 0.9, 0.9, 0.11, 0. (2) station b draws numbers: 0.45, 0.28, 0.11, 0.83, 0.37, 0.22, 0. (3)station c draws numbers: 0.1, 0.2, 0.3, 0.4, 0. (4) station d draws numbers: 0.36, 0.77, 0.9, 0.1, 0.1, 0.1, 0.1, 0. (b) in slotted aloha, a station transmits in each time slot with a given probability. what probabilities would you assign to each of the four stations so as to: (i) maximize the efficiency of the protocol? (ii) maximize fairness among the four stations? (c) will the efficiency increase or decrease if we modify slotted aloha as follows: (i) get rid of slots and allow stations to transmit immediately? (ii) implement carrier sensing? (iii) implement collision detection? (iv) implement collision avoidance?

Creating "smart interfaces" in all sectors of industry, government, and the public arena is one of the fastest growing hct areas. these interfaces model, interpret, and analyze such human characteristics as speech, gesture, and vision. the field of biometrics, in which humans authenticate themselves to machines, is an area of considerable interest to hct practitioners. fingerprint scans are one of the most frequently used biometric options, and this article, biometric student identification: practical solutions for accountability & security in schools, makes a case for the implementation of fingerprint scans in schools. critique the article, and answer the following questions: according to the author, what are the main benefits of adopting fingerprint scans in schools for student identification? according to the author, what are the main drawbacks of adopting fingerprint scans in schools for student identification? do you agree with the author's assessment of the pl

Scientists have changed the model of the atom as they have gathered new evidence. one of the atomic models is shown below. what experimental evidence led to the development of this atomic model from the one before it? a few of the positive particles aimed at a gold foil seemed to bounce back. the colors of light emitted from heated atoms had very specific energies. experiments with water vapor showed that elements combine in specific proportions. cathode rays were bent in the same way whenever a magnet was brought near them.