Strong Dependence of Atmospheric Feedbacks on Mixed-Phase Microphysics and Aerosol-Cloud Interactions in HadGEM3.

We analyze the atmospheric processes that explain the large changes in radiative feedbacks between the two latest climate configurations of the Hadley Centre Global Environmental model. We use a large set of atmosphere-only climate change simulations (amip and amip-p4K) to separate the contributions to the differences in feedback parameter from all the atmospheric model developments between the two latest model configurations. We show that the differences are mostly driven by changes in the shortwave cloud radiative feedback in the midlatitudes, mainly over the Southern Ocean. Two new schemes explain most of the differences: the introduction of a new aerosol scheme and the development of a new mixed-phase cloud scheme. Both schemes reduce the strength of the preexisting shortwave negative cloud feedback in the midlatitudes. The new aerosol scheme dampens a strong aerosol-cloud interaction, and it also suppresses a negative clear-sky shortwave feedback. The mixed-phase scheme increases the amount of cloud liquid water path (LWP) in the present day and reduces the increase in LWP with warming. Both changes contribute to reducing the negative radiative feedback of the increase of LWP in the warmer climate. The mixed-phase scheme also enhances a strong, preexisting, positive cloud fraction feedback. We assess the realism of the changes by comparing present-day simulations against observations and discuss avenues that could help constrain the relevant processes.

Analyzing Raman - Infrared spectral correlation in the recently found meteorite Csátalja.

Correlating the Raman and infrared spectra of shocked minerals in Csátalja ordinary chondrite (H4, S2, W2) with controlling the composition by EPMA measurements, we identified and improved various shock indicators, as infrared spectro-microscopic analysis has been poorly used for shock impact alteration studies of meteorites to date. We also provide reference spectra as SOM for the community with local mineralogical and shock alteration related context to support further standardization of the IR ATR based measurements. Raman band positions shifted in conjunction with the increase in full width half maximum (FWHM) with shock stage in olivine minerals while in the infrared spectra when comparing the IR band positions and IR maximal absorbance, increasing correlation was found as a function of increasing shock effects. This is the first observational confirmation with the ATR method of the already expected shock related disordering. In the case of shocked pyroxenes the well-known peak broadening and peak shift was confirmed by Raman method, beyond the level that could have been produced by only chemical changes. With increasing shock level the 852-864cm-1 and 1055-1071cm-1 FTIR bands finally disappeared. From the shock effect occasionally mixed mineral structures formed, especially feldspars together with pyroxene. Feldspars were only present in the shock melted volumes, thus produced by the shock effect itself. Based on the above mentioned observations in Csátalja meteorite the less shocked (only fractured) part witnessed 2-6GPa shock pressure with temperature below 100°C. The moderately shocked parts (minerals with mosaicism and mechanical twins) witnessed 5-10GPa pressure and 900°C temperature. The strongly shocked area (many olivine and pyroxene grains) was subject to 10-15GPa and 1000°C. The existence of broad peak near 510cm-1 and disappearance of other peaks of feldspar at 480 and 570cm-1 indicate the presence of maskelynite, which proposes that the peak shock pressure could reach 20GPa at certain locations. We identified higher shock levels than earlier works in this meteorite and provided examples how heterogeneous the shock effect and level could be at small spatial scale. The provided reference spectra support the future improvement for the standardization of infrared ATR based methods and the understanding of shock-related mineral alterations beyond the optical appearance.

The Met Office Hadley Centre climate modelling capability: the competing requirements for improved resolution, complexity and dealing with uncertainty.

Predictions of future climate change require complex computer models of the climate system to represent the full range of processes and interactions that influence climate. The Met Office Hadley Centre uses 'families' of models as part of the Met Office Unified Model Framework to address different classes of problems. The HadGEM family is a suite of state-of-the-art global environment models that are used to reduce uncertainty and represent and predict complex feedbacks. The HadCM3 family is a suite of well established but cheaper models that are used for multiple simulations, for example, to quantify uncertainty or to test the impact of multiple emissions scenarios.

Rubella immunity in a cohort of pregnant women.

To assess the rubella immune status of a cohort of high-risk pregnant women visiting a Midwestern clinic, we retrospectively studied 50 random pregnancies per year from 1990 through 1996. Of 350 patients analyzed, 53 (15.1%) were not immune to rubella, and vaccination opportunities were missed.

Prospective randomised trial of povidone-iodine, alcohol, and chlorhexidine for prevention of infection associated with central venous and arterial catheters.

More than 90% of all intravascular device-related septicaemias are due to central venous or arterial catheters. To assess the efficacy of cutaneous antisepsis to prevent catheter-associated infection, we prospectively studied three antiseptics for disinfection of patients' central venous and arterial catheter insertion sites in a surgical intensive care unit. 668 catheters were randomised to 10% povidone-iodine, 70% alcohol, or 2% aqueous chlorhexidine disinfection of the site before insertion and for site care every other day thereafter. Chlorhexidine was associated with the lowest incidence of local catheter-related infection (2.3 per 100 catheters vs 7.1 and 9.3 for alcohol and povidone-iodine, respectively, p = 0.02) and catheter-related bacteraemia (0.5 vs 2.3 and 2.6). Of the 14 infusion-related bacteraemias (4 due to contaminated infusate or catheter hub, 10 due to infected catheters), 1 was in the chlorhexidine group and 13 were in the other two groups (odds ratio 0.16, p = 0.04). We conclude that use of 2% chlorhexidine, rather than 10% povidone-iodine or 70% alcohol, for cutaneous disinfection before insertion of an intravascular device and for post-insertion site care can substantially reduce the incidence of device-related infection.

Risk factors for infusion-related phlebitis with small peripheral venous catheters. A randomized controlled trial.

OBJECTIVE: To identify risk factors for infusion-related phlebitis with peripheral intravenous catheters. DESIGN: A randomized trial of two catheter materials, with consideration of 21 potential risk factors. SETTING: A university hospital. PATIENTS: Hospitalized adults without granulocytopenia who received a peripheral intravenous catheter. INTERVENTIONS: House officers or ward nurses inserted the catheters, and each insertion was randomized to a catheter made of tetrafluoroethylene-hexafluoropropylene (FEP-Teflon) or a novel polyetherurethane without leachable additives (PEU-Vialon). MEASUREMENTS: Research nurses scored insertion sites each day for inflammation and cultured catheters at removal. RESULTS: The Kaplan-Meier risk for phlebitis exceeded 50% by day 4 after catheterization. intravenous antibiotics (relative risk, 2.00), female sex (relative risk, 1.88), prolonged (greater than 48 hours) catheterization (relative risk, 1.79), and catheter material (PEU-Vialon: FEP-Teflon) (relative risk, 0.73) strongly predicted phlebitis in a Cox proportional hazards model (each, P less than 0.003). The best-fit model for severe phlebitis identified the same predictors plus catheter-related infection (relative risk, 6.19), phlebitis with a previous catheter (relative risk, 1.54), and anatomic site (hand: forearm, relative risk, 0.71; wrist:forearm, relative risk, 0.60). The low incidence of local catheter-related infection was comparable with the two catheter materials (5.4% [95% CI, 3.8% to 7.6%] and 6.9% [CI, 4.9% to 9.6%]); none of the 1054 catheters prospectively studied caused bacteremia. CONCLUSIONS: Multiple factors, including the infusate and the duration of cannulation, contribute to the development of infusion-related phlebitis. The use of peripheral intravenous catheters made of PEU-Vialon appears to pose the same risk for catheter-related infection as the use of catheters made of FEP-Teflon, and PEU-Vialon can permit longer cannulation with less risk for phlebitis. The risk for catheter-related bacteremia with FEP-Teflon and PEU-Vialon catheters is sufficiently low that it no longer seems justifiable to recommend the use of small steel needles for most peripheral intravenous therapy.

An attachable silver-impregnated cuff for prevention of infection with central venous catheters: a prospective randomized multicenter trial.

PURPOSE: Percutaneously inserted central venous catheters are widely used. Catheter-related bacteremia or fungemia is the most frequent serious complication of these catheters. In an attempt to reduce the frequency of such infections, a subcutaneous cuff constructed of a biodegradable collagen matrix impregnated with bactericidal silver was developed. Our goal was to assess, in a multicenter clinical trial, the effectiveness of this cuff in preventing catheter-related infection. MATERIALS AND METHODS: Central venous catheters needed for fluid or drug therapy, hemodynamic monitoring, or hyperalimentation in patients in three centers were randomly assigned to be inserted with or without the cuff. Patients and catheters in the two groups were comparable in terms of risk factors predisposing to infection, including colonization of skin about the insertion site. RESULTS: The results with 234 catheters inserted into a new site showed that catheters inserted with the cuff were threefold less likely to be colonized on removal (more than 15 colony-forming units) than were control catheters (28.9 percent versus 9.1 percent, p = 0.002) and were nearly fourfold less likely to produce bacteremia (3.7 percent versus 1.0 percent). Adverse effects from the cuff were not seen. The cuff did not confer protection, however against infection with catheters inserted over a guidewire into old sites. Most of the catheter-related infections identified in this study, including four of the six bacteremias, appear to have been caused by microorganisms colonizing skin about the insertion site, affirming the pathogenetic basis for benefit seen with the cuff in this clinical trial; two may have derived from contamination of the catheter hub. CONCLUSION: This novel, silver-impregnated, attachable cuff can substantially reduce the incidence of catheter-related infection with most percutaneously inserted central venous catheters, can extend the time catheters can be left in place safely, and can prove cost-beneficial.

[3H]QNB binding and contraction of rabbit colonic smooth muscle cells.

We used radioligand binding and studies of cell contraction to characterize muscarinic receptors on dispersed smooth muscle cells from rabbit proximal and distal colon. Cells obtained after serial incubations in collagenase were used to measure binding of tritiated quinuclidinyl benzilate [( 3H]QNB). AT 37 degrees C, specific [3H]QNB binding was saturable and linearly related to cell number. Nonlinear regression analysis was used to determine the affinity of [3H]QNB for its receptor. In the distal colon the Kd was 60 pM, and the mean number of receptors was 1.2 X 10(6)/cell. Compared with cells from the distal colon, cells from the proximal colon had a lower affinity (Kd = 337 pM) but similar numbers of receptors. The concentrations of the antagonists atropine, secovorine, and pirenzepine, which were required for inhibition of 50% [3H]QNB binding (IC50), were 8, 5, and 870 nM, respectively, suggesting that the receptors are of the M2-muscarinic subclass. Hill coefficients for these agents were 1.1, 0.9, and 1.1, suggesting binding to a single receptor. The IC50 for the muscarinic agonists bethanechol and oxotremorine were 80 and 0.57 microM, respectively. Hill coefficients were 0.67 for both, suggesting more complex interactions involving receptors of different affinities. In studies of cell contraction, bethanechol stimulated a dose-dependent decrease in cell length with half the maximal contraction occurring at 100 pM. These results suggest that 1) contraction is mediated by binding of bethanechol to M2-muscarinic receptors and that 2) there are a large number of spare receptors in colonic smooth muscle.

Evaluation of dressing regimens for prevention of infection with peripheral intravenous catheters. Gauze, a transparent polyurethane dressing, and an iodophor-transparent dressing.

Four dressing regimens for peripheral venous catheters were studied in a prospective randomized clinical trial with 2088 Teflon catheters: (1) sterile gauze, replaced every other day, and three dressings left on for the lifetime of the catheter; (2) gauze; (3) a transparent polyurethane dressing; and (4) an iodophor-transparent dressing. The four dressings provided comparable coverage, except moisture accumulated more frequently under the transparent dressings (26% to 28% vs 20% to 21%). Cutaneous colonization under the dressing was low level and comparable with all four dressings (range, 10(0.58) to 10(0.70) colony-forming units). The rate of local catheter-related infection (greater than or equal to 15 colony-forming units) was also low and did not differ significantly (range, 4.6% to 5.9%); no catheter caused bacteremia. Stepwise logistic multivariate analysis showed cutaneous colonization of the insertion site (relative risk [RR] of infection, 3.86), contamination of the catheter hub (RR, 3.78), moisture under the dressing (RR, 2.48), and prolonged catheterization (RR, 1.75) to be significant risk factors for catheter-related infection. These data indicate that it is not cost-effective to redress peripheral venous catheters at periodic intervals; for most patients, either sterile gauze or a transparent dressing can be used and left on until the catheter is removed.

The role of dental restorative metals in the pathogenesis of oral lichen planus.

Twenty-four subjects with oral lichen planus and twelve control subjects without oral mucosal disease were patch tested with dental restorative metals and selected metallic salts. Twenty-one percent of the lichen planus population exhibited a positive skin response to one or more challenge materials, as compared to 8% of the control population. It is concluded that oral lichen planus subjects show a higher correlation with delayed hypersensitivity to dental metals than a control population; however, a cause-and-effect relationship cannot be substantiated.

Mitral valve prolapse: jet stream causing mural endocarditis.

A 53 year old man died of cerebral hemorrhage while being treated for Streptococcus mutans endocarditis. At autopsy the only endocarditic lesion was on the left atrial mural endocardium. The noninfected mitral valve demonstrated prolapse and mucinous degeneration. The latter had led to rupture of several chordae tendineae, with the resultant jet stream predisposing to endocarditis at its point of atrial impact. The case provides confirmation of current concepts of the pathogenesis of endocarditis and has important therapeutic implications.