Through-silicon-via aware interconnect prediction and optimization for 3D stacked ICs

Individual dies in 3D integrated circuits are connected using through-silicon-vias (TSVs). TSVs not only increase manufacturing cost, but also incur silicon area, delay, and power overhead. However, the effects of TSV overheads have not been studied thoroughly in the literature. In this paper, we analyze the impact of TSVs on silicon area and wirelength. We derive a new 3D wirelength distri-bution model considering TSV size. Based on this new prediction model, we explain the impact of several design parameters newly introduced in 3D ICs. We also present a case study to show how the model can help make early design decisions for 3D ICs

Phosphorus in the Young Supernova Remnant Cassiopeia A

Phosphorus (^(31)P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here, we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron (^(56)Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion

Comparative effects of norepinephrine and vasopressin on internal thoracic arterial graft flow after off-pump coronary artery bypass grafting

ObjectiveVasoconstrictors such as norepinephrine and vasopressin are commonly used to raise the blood pressure during myocardial revascularization. The internal thoracic artery is commonly used for coronary artery grafting because of its long-term patency. However, the internal thoracic artery is a living conduit that responds to vasoactive substances. The objective of this study was to measure change in internal thoracic arterial flow after infusion of norepinephrine or vasopressin.MethodsForty-one patients undergoing elective off-pump coronary artery bypass grafting participated in this study. After the median sternotomy, the left internal thoracic artery was dissected with a pedicle and grafted to the left anterior descending artery. After all anastomoses were performed and hemodynamic parameters were stable, the grafted internal thoracic arterial blood flow was measured by transit time flowmeter on the distal portion of the graft as a baseline. Norepinephrine or vasopressin was then infused until mean arterial pressure was increased to 20% of baseline. Graft flow and hemodynamic variables were measured when mean arterial pressure reached the intended level.ResultsBaseline grafted internal thoracic arterial flows were similar (norepinephrine 57.1 ± 17.7 mL min−1, vasopressin 66.0 ± 34.3 mL min−1). With norepinephrine, flow increased significantly relative to baseline (77.2 ± 31.0 mL min−1); with vasopressin, it remained unchanged (68.3 ± 37.0 mL min−1).ConclusionsFor patients needing vasopressor support after coronary artery bypass grafting, norepinephrine appeared superior to vasopressin because of increased internal thoracic arterial flow