We measured heat capacities of two dimensional 3He adsorbed on graphite preplated with a 4He monolayer (3He/4He/gr) in a wide temperature (0.3 < or = T < or = 80 mK) and density range (1.3 < or = p < ...or = 7.3 nm-2). We found that the system behaves as a normal Fermi fluid at low densities between 1.3 and 5.6 nm-2 where the quasiparticle effective mass seems to diverge at a density for the 4/7 phase (rho4/7 = 6.8 nm-2). At higher densities but below rho4/7, we observed anomalous temperature dependencies of heat capacity with two round maxima near 1 and 30 mK. With increasing density in this region, a high temperature weight of heat capacity decreases selectively leaving the 30 mK peak, while the 1 mK peak develops. This unexpected behavior can not be explained by the conventional two-phase co-existence model. Instead, we propose here that the 2D normal Fermi fluid is continuously transformed to the 4/7 Mott localized phase through a new quantum phase where a hopping of the zero-point vacancy plays an important role.
Summary In the face of diminishing therapeutic options for the treatment of infections caused by multidrug-resistant, Gram-negative bacteria, clinicians are increasingly using colistin and polymyxin ...B. These antibiotics became available clinically in the 1950s, when understanding of antimicrobial pharmacology and regulatory requirements for approval of drugs was substantially less than today. At the 1st International Conference on Polymyxins in Prato, Italy, 2013, participants discussed a set of key objectives that were developed to explore the factors affecting the safe and effective use of polymyxins, identify the gaps in knowledge, and set priorities for future research. Participants identified several factors that affect the optimum use of polymyxins, including: confusion caused by several different conventions used to describe doses of colistin; an absence of appropriate pharmacopoeial standards for polymyxins; outdated and diverse product information; and uncertainties about susceptibility testing and breakpoints. High-priority areas for research included: better definition of the effectiveness of polymyxin-based combination therapy compared with monotherapy via well designed, randomised controlled trials; examination of the relative merits of colistin versus polymyxin B for various types of infection; investigation of pharmacokinetics in special patient populations; and definition of the role of nebulised polymyxins alone or in combination with intravenous polymyxins for the treatment of pneumonia. The key areas identified provide a roadmap for action regarding the continued use of polymyxins, and are intended to help with the effective and safe use of these important, last-line antibiotics.
A monolayer of 3He adsorbed on graphite surface preplated with a mono-layer of 4 He constitutes an ideal model system for studying strongly correlated two-dimensional fermions. The system behaves as ...a fluid phase at low densities and as the density is increased, accompanied by a Mott localization, it approaches the 4/7 registered phase. Recent heat-capacity measurements suggest that before the Mott transition, there exists an intermediate hole-doped Mott localized phase. We started new NMR measurements focusing on this novel phase to verify its existence and characteristics. We measured the static magnetization of the system down to 10 mK as a function of density. The magnetization data continuously intervene the fluid phase and the 4/7 phase, and support the above mentioned scenario.
We measured heat capacities of the second layer 3He admixed with a small amount of 4He (= 0.9 nm-2) on graphite preplated with a monolayer 4He. The aim of this study is to elucidate possible 4He ...substitution effects on a recently proposed new quantum phase existing at densities just below that (rho4/7) for the 4/7 registered phase. This phase is supposed to be the hole (zero-point vacancy) doped Mott localized phase. The substitution gives rise to an excess heat capacity (Cex) with unusual temperature and density dependencies which is most pronounced at a slightly lower density than rho4/7. The Cex stays relatively large even at rho4/7, and suddenly disappears at a slightly higher density. One possible scenario, which is consistent with the present data, is that the Cex comes from the isotopic mixing effect existing in a narrow density range around rho4/7 and that there exists an excess particle phase just above rho4/7 in addition to the hole doped phase below. The result may suggest finite fluidity or unexpectedly large band widths for the isotopic impurities in the 4/7 phase.
Background Tubular plastic and metal stents have inherent shortcomings when used for transenteric drainage of fluid collections. Objective To evaluate a novel lumen-apposing, self-expandable metal ...stent for EUS-guided drainage of pancreatic pseudocysts and the gallbladder. Design Retrospective case series. Setting Tertiary-care academic medical center. Patients This study involved 15 patients (median age 54 years) with symptomatic pancreatic pseudocysts who underwent 12 transgastric and 3 transduodenal pseudocyst drainage procedures. Five patients (median age 69.5 years) with acute cholecystitis underwent 4 cholecystoduodenostomies and 1 cholecystogastostomy. Intervention Stent deployment under EUS guidance, passage of an endoscope through the stent lumen for pseudocystoscopy or cholecystoscopy, transenteric endoscopy-guided interventions including biopsy, necrosectomy, and stone removal. Main Outcome Measurements Technical and clinical success. Results All stents were successfully deployed without complication, with a median time to removal of 35 days. All pseudocysts resolved after a single drainage procedure. One stent migrated into the stomach, and the remaining 14 were found to be patent at the time of removal. There was no pseudocyst recurrence during the 11.4-month median follow-up period. One gallbladder stent remains indwelling and fully patent at 12 months. Resolution of acute cholecystitis was observed immediately after stent implantation. No recurrence of symptoms was observed during a median follow-up period of 9 months. Limitations Retrospective study, small sample size, lack of control patients. Conclusion Transenteric drainage of pancreatic pseudocysts and the gallbladder by using a novel, lumen-apposing, metal stent was accomplished with high technical and clinical success in this pilot observational study. Further studies are warranted.
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