Electron-positron outflow from black holes

Gamma-ray bursts (GRBs) appear as the brightest transient phenomena in the Universe. The nature of the central engine in GRBs is a missing link in the theory of fireballs to their stellar mass progenitors. Here it is shown that rotating black holes produce electron-positron outflow when brought into contact with a strong magnetic field. The outflow is produced by a coupling of the spin of the black hole to the orbit of the particles. For a nearly extreme Kerr black hole, particle outflow from an initial state of electrostatic equilibrium has a normalized isotropic emission of $\sim 5\times10^{48}(B/B_c)^2(M/7M_\odot)^2\sin^2\theta$ erg/s, where B is the external magnetic field strength, B_c=4.4 x 10^{13}G, and M is the mass of the black hole. This initial outflow has a half-opening angle $\theta\ge\sqrt{B_c/3B}$. A connection with fireballs in $\gamma$-ray bursts is given.Comment: 10 pages LaTe

Clinical outcomes of EUS-guided drainage of debris-containing pancreatic pseudocysts: a large multicenter study

Background and study aims Data on clinical outcomes of endoscopic drainage of debris-free pseudocysts (PDF) versus pseudocysts containing solid debris (PSD) are very limited. The aims of this study were to compare treatment outcomes between patients with PDF vs. PSD undergoing endoscopic ultrasound (EUS)-guided drainage via transmural stents. Patients and methods Retrospective review of 142 consecutive patients with pseudocysts who underwent EUS-guided transmural drainage (TM) from 2008 to 2014 at 15 academic centers in the United States. Main outcome measures included TM technical success, treatment outcomes (symptomatic and radiologic resolution), need for endoscopic re-intervention at follow-up, and adverse events (AEs). Results TM was performed in 90 patients with PDF and 52 with PSD. Technical success: PDF 87 (96.7 %) vs. PSD 51 (98.1 %). There was no difference in the rates for endoscopic re-intervention (5.5 % in PDF vs. 11.5 % in PSD; P = 0.33) or AEs (12.2 % in PDF vs. 19.2 % in PSD; P = 0.33). Median long-term follow-up after stent removal was 297 days (interquartile range [IQR]: 59 - 424 days) for PDF and 326 days (IQR: 180 - 448 days) for PSD (P = 0.88). There was a higher rate of short-term radiologic resolution of PDF (45; 66.2 %) vs. PSD (21; 51.2 %) (OR = 0.30; 95 % CI: 0.13 - 0.72; P = 0.009). There was no difference in long-term symptomatic resolution (PDF: 70.4 % vs. PSD: 66.7 %; P = 0.72) or radiologic resolution (PDF: 68.9 % vs. PSD: 78.6 %; P = 0.72) Conclusions There was no difference in need for endoscopic re-intervention, AEs or long-term treatment outcomes in patients with PDF vs. PSD undergoing EUS-guided drainage with transmural stents. Based on these results, the presence of solid debris in pancreatic fluid collections does not appear to be associated with a poorer outcome

Transpapillary drainage has no added benefit on treatment outcomes in patients undergoing EUS-guided transmural drainage of pancreatic pseudocysts: a large multicenter study

Background and Aims The need for transpapillary drainage (TPD) in patients undergoing transmural drainage (TMD) of pancreatic fluid collections (PFCs) remains unclear. The aims of this study were to compare treatment outcomes between patients with pancreatic pseudocysts undergoing TMD versus combined (TMD and TPD) drainage (CD) and to identify predictors of symptomatic and radiologic resolution. Methods This is a retrospective review of 375 consecutive patients with PFCs who underwent EUS-guided TMD from 2008 to 2014 at 15 academic centers in the United States. Main outcome measures included TMD and CD technical success, treatment outcomes (symptomatic and radiologic resolution) at follow-up, and predictors of treatment outcomes on logistic regression. Results A total of 375 patients underwent EUS-guided TMD of PFCs, of which 174 were pseudocysts. TMD alone was performed in 95 (55%) and CD in 79 (45%) pseudocysts. Technical success was as follows: TMD, 92 (97%) versus CD, 35 (44%) (P = .0001). There was no difference in adverse events between the TMD (15%) and CD (14%) cohorts (P = .23). Median long-term (LT) follow-up after transmural stent removal was 324 days (interquartile range, 72-493 days) for TMD and 201 days (interquartile range, 150-493 days) (P = .37). There was no difference in LT symptomatic resolution (TMD, 69% vs CD, 62%; P = .61) or LT radiologic resolution (TMD, 71% vs CD, 67%; P = .79). TPD attempt was negatively associated with LT radiologic resolution of pseudocyst (odds ratio, 0.11; 95% confidence interval, 0.02-0.8; P = .03). Conclusions TPD has no benefit on treatment outcomes in patients undergoing EUS-guided TMD of pancreatic pseudocysts and negatively affects LT resolution of PFCs

“By ones and twos and tens”: pedagogies of possibility for democratizing higher education

This paper concerns the relationship between teaching and political action both within and outside formal educational institutions. Its setting is the recent period following the 2010 Browne Review on the funding of higher education in England. Rather than speaking directly to debates around scholar-activism, about which much has already been written, I want to stretch the meanings of both teaching and activism to contextualise the contemporary politics of higher learning in relation to diverse histories and geographies of progressive education more generally. Taking this wider view suggests that some of the forms of knowledge which have characterised the university as a progressive institution are presently being produced in more politicised educational environments. Being receptive to these other modes of learning can not only expand scholarly thinking about how to reclaim intellectual life from the economy within universities, but stimulate the kind of imagination that we need for dreaming big about higher education as and for a practice of democratic life

THE METABOLISM OF CHYLOMICRON CHOLESTEROL ESTER IN THE RAT

The lymphatic transport of cholesterol is of great quantitative importance in the over-all me-tabolism of cholesterol. It is now well established that exogenous cholesterol is absorbed almost ex-clusively by way of the intestinal lymph (1, 2), where most of the newly absorbed cholesterol is found esterified, in the chylomicron fraction (3, 4). Estimates of the extent of esterification have varied from 90 per cent at the peak of cholesterol absorption (3) to an average of 72 + 6 per cent over a wide range of absorption (4). In addi-tion, a considerable amount of endogenous cho-lesterol from the bile and the intestinal mucosa is absorbed and transported in an identical fashion. Surprisingly little detailed information exists