Merging and Splitting in Cooperative Games: Some (Im-)Possibility Results

Solutions for cooperative games with side-payments can be manipulated by merging a coalition of players into a single player, or, conversely, splitting a player into a number of smaller players. This paper establishes some (im-)possibility results concerning merging- or splitting-proofness of core solutions of balanced and convex games.cooperative games; manipulation; Dutta-Ray solution

Testing and Analysis of an Exergetically Efficient 4 K to 2 K Helium Heat Exchanger

Modern experimental nuclear physics programs that utilize advanced superconducting devices require refrigeration below the lambda temperature of helium (2.1768 K) and involve sub-atmospheric helium at some point in the process. They typically operate between 1.8 and 2.1 K (16 to 40 mbar) and can require refrigeration ranging from tens to thousands of watts. These processes are very energy intensive, requiring roughly 850 W/W even for large and well-designed refrigerators, though they can easily require much more. Adiabatic expansion of sub-cooled liquid helium to these sub-atmospheric pressures will result in a two-phase mixture with a large liquid to vapor density ratio. Since there are no practical expanders to handle this condition, a counter flow heat exchanger is used to cool the super-critical helium supply using the returning sub-atmospheric helium. Typically, the super-critical helium exiting this 4.5 K to 2-K counter flow heat exchanger is throttled across an expansion valve to a sub-atmospheric pressure. This is a substantial irreversibility, typically 13 percent of the enthalpy difference between the load supply and return. A significant process improvement is theoretically obtainable by handling the exergy loss across the expansion valve supplying the flow to the load in a simple but different manner. The exergy loss can be minimized by allowing the supply flow pressure to decrease to a sub-atmospheric pressure concurrent with heat exchange with the sub-atmospheric flow from the load. This dissertation work encompasses testing of a practical implementation using a Collin’s type heat exchanger to investigate the overall performance, as well as, the optimum selections of independent process parameters and how this affects the heat exchanger size distribution. The thermodynamics of heat exchange with a significant pressure drop for a non-ideal fluid are investigated, in regards to an equivalent expansion efficiency pseudo-property, a practical process expansion efficiency equivalence and an overall 2-K system performance improvement expectation. Theoretically predicted optimum independent process parameters are compared to those measured

Process Study for the Design of Small-Scale 2 Kelvin Refrigeration Systems

Helium refrigeration at temperatures below 4.5-Kelvin (K), but greater than 0.8-K typically employ a sub-atmospheric process utilizing a vacuum pumping system. These types of helium refrigerators are of keen interest to present and future particle physics programs utilizing super-conducting magnet or radio-frequency technology. As such, there is a need for small scale 2-K helium refrigeration systems (i.e., those that operated below the lambda temperature) in small laboratories and test facilities at this time. This study establishes the key process parameter choices of flow ratio, heat-exchanger size, and supply pressure, and how they influence the overall system performance for various process configurations that do not utilize rotating machinery within the cold box (i.e., turbo-machinery for either cryogenic vacuum pumping or expansion) but do utilize a separate commercially available 4.5-K helium liquefier system. Three 2-K process configurations are studied to determine the key process parameter values that yield the best performance. These process configurations are compared to the commonly employed (but inefficient) direct vacuum pumping process, which typically uses a dewar as the 4.5-K liquid helium supply source. It is found that the performance of these configurations is similar and substantially superior to direct vacuum pumping, providing an inverse coefficient of performance of around 1800 W/W

Unique metabolic features of pancreatic cancer stroma: relevance to the tumor compartment, prognosis, and invasive potential.

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. The aggressiveness and therapeutic recalcitrance of this malignancy has been attributed to multiple factors including the influence of an active desmoplastic stroma. How the stromal microenvironment of PDAC contributes to the fatal nature of this disease is not well defined. In the analysis of clinical specimens, we observed diverse expression of the hypoxic marker carbonic anhydrase IX and the lactate transporter MCT4 in the stromal compartment. These stromal features were associated with the epithelial to mesenchymal phenotype in PDAC tumor cells, and with shorter patient survival. Cultured cancer-associated fibroblasts (CAFs) derived from primary PDAC exhibited a high basal level of hypoxia inducible factor 1a (HIF1α) that was both required and sufficient to modulate the expression of MCT4. This event was associated with increased transcription and protein synthesis of HIF1α in CAFs relative to PDAC cell lines, while surprisingly the protein turnover rate was equivalent. CAFs utilized glucose predominantly for glycolytic intermediates, whereas glutamine was the preferred metabolite for the TCA cycle. Unlike PDAC cell lines, CAFs were resistant to glucose withdrawal but sensitive to glutamine depletion. Consistent with the lack of reliance on glucose, CAFs could survive the acute depletion of MCT4. In co-culture and xenograft studies CAFs stimulated the invasive potential and metastatic spread of PDAC cell lines through a mechanism dependent on HIF1α and MCT4. Together, these data indicate that stromal metabolic features influence PDAC tumor cells to promote invasiveness and metastatic potential and associate with poor outcome in patients with PDAC

The Fertility Pattern of Twins and the General Population Compared: Evidence from Danish Cohorts 1945-64

Twin studies provide an important possibility for demographers to analyze patterns of heritability and to estimate structural models with controls for endowments. These possibilities are increasingly used in the context of fertility and related behaviors. A close congruence between the fertility patterns of twins and that of the general population, however, is an essential pre-condition in order to generalize the results of twin-based investigations of fertility and related behaviors to the general population. In this paper we therefore compare the fertility of Danish twins born 1945--64 to the fertility pattern of the general population born during the same period. Our analyses find a very close correspondence between the fertility pattern of twins and of the general population. There exist only few statistically significant differences, and the primary difference pertains to the fact that female twins have a slightly later onset of childbearing than non-twins. There are virtually no relevant differences between the fertility patterns of dizygotic and monozygotic twins.cohort fertility, Denmark, fertility, twin studies

Integrating communication protocol selection with partitioning in hardware/software codesign

This paper presents a codesign approach which incorpo-rates communication protocol selection as a design param-eter within hardware/software partitioning. The presented approach takes into account data transfer rates depending on communication protocol types and configurations, and different operating frequencies of system components, i.e. CPUs, ASICs, and busses. It also takes into account the tim-ing and area influences of drivers and driver calls needed to perform the communication. The approach is illustrated by a number of design space exploration experiments which use models of the PCI and USB communication protocols. 1

PACE: A dynamic programming algorithm for hardware/software partitioning

. This paper presents the PACE partitioning algorithm which is used in the LYCOS co-synthesis system for partitioning control/dataflow graphs into hardwareand software parts. The algorithm is a dynamic programming algorithm which solves both the problem of minimizing system execution time with a hardware area constraint and the problem of minimizing hardware area with a system execution time constraint. The target architecture consists of a single microprocessor and a single hardware chip (ASIC, FPGA, etc.) which are connected by a communication channel. The algorithm incorporates a realistic communication model and thus attempts to minimize communication overhead. The time-complexity of the algorithm is O(n 2 \Delta A) and the space-complexity is O(n \Delta A) where A is the total area of the hardware chip and n the number of code fragments which may be placed in either hardware or software. 1 Introduction The hardware/software partitioning of a system specification onto a target..