A Smart Game for Data Transmission and Energy Consumption in the Internet of Things

The current trend in developing smart technology for the Internet of Things (IoT) has motivated a lot of research interest in optimizing data transmission or minimizing energy consumption, but with little evidence of proposals for achieving both objectives in a single model. Using the concept of game theory, we develop a new MAC protocol for IEEE 802.15.4 and IoT networks in which we formulate a novel expression for the players' utility function and establish a stable Nash equilibrium (NE) for the game. The proposed IEEE 802.15.4 MAC protocol is modeled as a smart game in which analytical expressions are derived for channel access probability, data transmission probability, and energy used. These analytical expressions are used in formulating an optimization problem (OP) that maximizes data transmission and minimizes energy consumption by nodes. The analysis and simulation results suggest that the proposed scheme is scalable and achieves better performance in terms of data transmission, energy-efficiency, and longevity, when compared with the default IEEE 802.15.4 access mechanism.Peer reviewe

Causes of Appreciation and Volatility of the Dollar with Comment by Jacob Frenkel

In 1981 real interest rates in the United States increased spectacularly, and the dollar appreciated in real terms by about 20 percent. Since the end of 1981, long-term real interest rates have remained in the range of 5-10 percent, with nominal long rates above short rates. The dollar appreciated further, but more gradually, until early 1985. This paper argues that these movements in real interest rates and the real exchange rate are due to the shift in the high-employment deficit by some $200 billion that was announced in the 1981 budget program. This requires an increase in real interest rates and a real appreciation to generate the sum of excess domestic saving and foreign borrowing to finance it. The argument is a straightforward extension of the idea of "crowding out" at full employment to an open economy.The current situation is not sustainable, however. Eventually international investors will begin to resist further absorption of dollars into their portfolios, so U.S. interest rates will have to rise further, as the markets seem to expect, and the dollar will have to depreciate. This will continue until the current account is back in approximate balance, and the entire load of deficit financing is shifted to excess U.S. saving. In his comments on Branson's paper, Jacob A. Frenkel discusses additional factors that have contributed to the evolution of the dollar since 1980. He concludes that in addition to U.S. fiscal policies, monetary policy in the United States and the fiscal position of the U.K., West Germany and Japan have also contributed to the dollar's strength.

Vertically emitting annular Bragg lasers using polymer epitaxial transfer

Fabrication of a planar semiconductor microcavity, composed of cylindrical Bragg reflectors surrounding a radial defect, is demonstrated. A versatile polymer bonding process is used to transfer active InGaAsP resonators to a low-index transfer substrate. Vertical emission of in-plane modes lasing at telecom wavelengths is observed under pulsed optical excitation with a submilliwatt threshold

The formation of glycocyamine in man and its urinary excretion

Glycocyamine was first isolated from human and dog urine and identified by Weber (1-3). He supported the view that glycocyamine is a normal precursor of creatine and that its appearance in urine (2) is “an overflow phenomenon of an intermediate metabolic product ...” He expressed no views on the mechanism of its formation