The composition of the protosolar disk and the formation conditions for comets

Conditions in the protosolar nebula have left their mark in the composition of cometary volatiles, thought to be some of the most pristine material in the solar system. Cometary compositions represent the end point of processing that began in the parent molecular cloud core and continued through the collapse of that core to form the protosun and the solar nebula, and finally during the evolution of the solar nebula itself as the cometary bodies were accreting. Disentangling the effects of the various epochs on the final composition of a comet is complicated. But comets are not the only source of information about the solar nebula. Protostellar disks around young stars similar to the protosun provide a way of investigating the evolution of disks similar to the solar nebula while they are in the process of evolving to form their own solar systems. In this way we can learn about the physical and chemical conditions under which comets formed, and about the types of dynamical processing that shaped the solar system we see today. This paper summarizes some recent contributions to our understanding of both cometary volatiles and the composition, structure and evolution of protostellar disks.Comment: To appear in Space Science Reviews. The final publication is available at Springer via http://dx.doi.org/10.1007/s11214-015-0167-

Heterodyne receiver for Origins

Instrumentatio

Correlation of cyclin D1 and cyclin D3 overexpression with the loss of PTEN expression in endometrial carcinoma

Cyclins D1 and D3 play key roles in cell cycle progression. The downregulation of cyclin D3 was associated with phosphatase and tensin homolog deleted on chromosome ten‐(PTEN)‐induced cell cycle arrest. We attempted to determine whether cyclin D1 and D3 overexpression is correlated with PTEN inactivation in endometrioid endometrial cancer (EEC). The expression of PTEN, cyclin D1, and cyclin D3 were determined by immunohistochemical analysis in 105 EEC specimens. Forty‐three percent of the EEC demonstrated loss of PTEN expression. Cyclin D3 was overexpressed in only 18% of the EEC specimens and was not associated with tumor grade. Cyclin D1 was overexpressed in 64% of the specimens and was more common in moderate or high‐grade tumors (P= 0.002 and P= 0.02, respectively). The overexpression of cyclin D3 was not correlated with loss of PTEN in the EEC. The overexpression of cyclin D1 was much higher in grade 1 tumors with negative PTEN than tumors with positive PTEN expression (67% vs 26%). The overexpression of cyclin D3 was neither frequent nor correlated with the loss of PTEN expression. The overexpression of cyclin D1 was higher in the low‐grade tumors with negative PTEN expression than tumors with positive PTEN expression. Overexpression of cyclin D1 is frequent in moderate or high‐grade EECs and likely results from multiple mechanisms

Real-time Optimized Rendezvous on Nonholonomic Resource-Constrained Robots

Abstract In this work, we consider a group of differential-wheeled robots endowed with noisy relative positioning capabilities. We develop a decentralized approach based on a receding horizon controller to generate, in real-time, trajectories that guarantee the convergence of our robots to a common location (i.e. rendezvous). Our receding horizon controller is tailored around two numerical optimization methods: the hybrid-state A * and trust-region algorithms. To validate both methods and test their robustness to computational delays, we perform exhaustive experiments on a team of four real mobile robots equipped with relative positioning hardware