B fields from a Luddite perspective

In this talk we discuss the geometric realization of B fields and higher p-form potentials on a manifold M as connections on affine bundles over M. We realize D branes on M as special submanifolds of these affine bundles. As an application of this geometric understanding of the B field, we give a simple geometric explanation for the Chern-Simons modification of the field strength of the B field.Comment: 7 pages. From a talk given at the 3rd International Symposium on Quantum Theory and Symmetries (QTS3

Organizational Design for Spill Containment in Deepwater Drilling Operations in the Gulf of Mexico: Assessment of the Marine Well Containment Company (MWCC)

The Deepwater Horizon oil spill in the Gulf of Mexico in April 2010 led to the deaths of 11 workers, a six-month moratorium on deepwater drilling in the Gulf, and nearly three months of massive engineering and logistics efforts to stop the spill. The series of failures before the well was finally capped and the spill contained revealed an inability to deal effectively with a well in deepwater and ultradeepwater. Ensuring that containment capabilities are adequate for drilling operations at these depths is therefore a salient challenge for government and industry. In this paper we assess the Marine Well Containment Company (MWCC), a consortium aimed at designing and building a system capable of containing future deepwater spills in the Gulf. We also consider alternatives for long-term readiness for deepwater spill containment. We focus on the roles of liability and regulation as determinants of readiness and the adequacy of incentives for technological innovation in oil spill containment technology to keep pace with advances in deepwater drilling capability. Liability and regulation can significantly influence the strength of these incentives. In addition, we discuss appropriate governance structure as a major determinant of the effectiveness of MWCC.oil spill, containment, industry R&D, liability, regulation, governance, innovation

Unsuspected infection is infrequent in asymptomatic outpatients with refractory ascites undergoing therapeutic paracentesis

Large-volume paracentesis is a safe and effective means of treating patients with refractory ascites. However, there is limited information regarding the need for ascitic fluid studies in asymptomatic outpatients presenting for therapeutic paracentesis. The aim of this prospective study was to define the incidence and natural history of peritoneal fluid infection in asymptomatic outpatients undergoing therapeutic paracentesis. Methods : Over a 13-month period, 118 therapeutic paracenteses were performed in 29 outpatients with decompensated cirrhosis (Child-Pugh class B = 38%, C = 62%). After a brief medical history and physical examination, ascitic fluid cell count with differential and culture were obtained from all participating subjects. Seven (24%) of the subjects were receiving norfloxacin prophylaxis, accounting for antibiotic coverage during 40% of the procedures performed. The clinical course and outcome of study subjects during a mean follow-up of 137 days was reviewed. Results : All 118 (100%) of the ascitic fluid samples demonstrated absolute neutrophil counts of <250/mm 3 (mean = 6.5 ± 22.5 pmn/mm 3 ). Asymptomatic bacterascites was identified from three of the 118 (2.5%) fluid samples, but all of these subjects spontaneously recovered without treatment or sequelae. During follow-up, six episodes of symptomatic or hospital-associated peritoneal fluid infection were identified in study participants, emphasizing the importance of fluid studies in other clinical settings. Conclusion : Although further studies are needed, the routine culture of ascitic fluid in asymptomatic outpatients with refractory ascites requiring therapeutic paracentesis may not be necessary when there is a low index of suspicion for occult infection. In circumstances of clinical uncertainty, however, obtaining ascitic fluid cell counts with differential is recommended to insure patient safety.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73079/1/j.1572-0241.1999.01445.x.pd

IDCS J1426.5+3508: The Most Massive Galaxy Cluster at z>1.5z > 1.5

We present a deep (100 ks) Chandra observation of IDCS J1426.5+3508, a spectroscopically confirmed, infrared-selected galaxy cluster at $z = 1.75$. This cluster is the most massive galaxy cluster currently known at $z > 1.5$, based on existing Sunyaev-Zel'dovich (SZ) and gravitational lensing detections. We confirm this high mass via a variety of X-ray scaling relations, including $T_X$-M, $f_g$-M, $Y_X$-M and $L_X$-M, finding a tight distribution of masses from these different methods, spanning M$_{500}$ = 2.3-3.3 $\times 10^{14}$ M$_{\odot}$, with the low-scatter $Y_X$-based mass $M_{500,Y_X} = 2.6^{+1.5}_{-0.5} \times 10^{14}$ M$_\odot$. IDCS J1426.5+3508 is currently the only cluster at $z > 1.5$ for which X-ray, SZ and gravitational lensing mass estimates exist, and these are in remarkably good agreement. We find a relatively tight distribution of the gas-to-total mass ratio, employing total masses from all of the aforementioned indicators, with values ranging from $f_{gas,500}$ = 0.087-0.12. We do not detect metals in the intracluster medium (ICM) of this system, placing a 2$\sigma$ upper limit of $Z(r < R_{500}) < 0.18 Z_{\odot}$. This upper limit on the metallicity suggests that this system may still be in the process of enriching its ICM. The cluster has a dense, low-entropy core, offset by $\sim$30 kpc from the X-ray centroid, which makes it one of the few "cool core" clusters discovered at $z > 1$, and the first known cool core cluster at $z > 1.2$. The offset of this core from the large-scale centroid suggests that this cluster has had a relatively recent ($\lesssim$500 Myr) merger/interaction with another massive system.Comment: Minor changes to match accepted version, results unchanged; ApJ in pres