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Internal Revenue Code §183 generally prohibits taxpayers from deducting expenses related to activities in which the taxpayer is not primarily motivated by profit. The applicable Treasury Regulation provides nine specific factors to consider in determining if a taxpayer's activity is motivated primarily by profit. This paper reviews the United States Tax Court's application of the nine factors in a sample of decisions reported between 2005 and 2015, inclusive, investigating potential inconsistencies between the Regulation language and observed outcomes. We find that a taxpayer successfully demonstrating three factors has a 158 percent greater probability of winning than a taxpayer demonstrating only two factors. We also observe that operating in a businesslike manner is a key factor to taxpayer success. Finally, we show that pro se taxpayers generally fare worse than represented ones, although the marginal reward to an additional favorable factor may be higher for them than for represented taxpayers.

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The trend in both the computing and electronic industries is to reduce the size of the electronic components while increasing both their performance and capability. Innovative thermal management schemes are needed in order to reduce the impact of the thermal loads. Most of the current electronic components are packaged in a plastic or ceramic container to provide chip and electrical lead protection. Both of these packaging materials have low thermal conductivity, making heat removal from the chip difficult. Thus, heat transfer through the off-chip metal interconnects offers an additional heat removal path. Ball grid array (BGA) interconnects provide an efficient means to connecting packaged high performance chips to printed circuit boards (PCB). As area array bump density increases, reducing Joule heating and electromigration will play an important role in chip and interconnect reliability. Among the many types of interconnects, solder balls offer an efficient means of connecting a chip or package to a PCB. Direct cooling of the solder balls is a new approach to removing heat from packaged chips. Jet impingement presents a unique solution for cooling the solder balls. Thermal and computational fluid dynamic (CFD) modeling of a plastic ball grid array (PBGA) package has demonstrated a significant decrease in temperature across the chip, package, and solder balls, when using jet impingement cooling.Nomenclature k = Thermal Conductivity (W/mK) C p = Specific Heat (J/kgK) ρ = Density (kg/m 3 ) Q = Heat Generation Rate (W) h = Convective Heat Transfer Coefficient (W/m 2 K) K = Kelvin

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