Interfacial areas and gas hold-ups in bubble columns and packed bubble columns at elevated pressures

Interfacial areas and gas hold-ups have been determined at pressures up to 1.85 MPa in a bubble column with a diameter of 85.5 mm and for superficial gas velocities between 1 and 10 cm s−1. In some experiments the bubble column was packed with glass cylinders of length 5.0 mm and diameter 4.0 mm. The interfacial areas were determined by the chemical method using the model reaction between CO2 and aqueous diethanolamine (DEA) and hold-ups by observation of height differences.\ud \ud The interfacial areas in the packed bubble column are unaffected by pressure. The gas hold-ups as well as the interfacial areas in the bubble column increase with increasing operating pressure. The magnitude of the pressure influence depends on the superficial gas velocity. The positive influence of pressure on the gas hold-ups and the interfacial in the bubble column originates from the formation of smaller bubbles at the gas distributor

Waveform-based simulated annealing of crosshole transmission data: a semi-global method for estimating seismic anisotropy

We successfully apply the semi-global inverse method of simulated annealing to determine the best-fitting 1-D anisotropy model for use in acoustic frequency domain waveform tomography. Our forward problem is based on a numerical solution of the frequency domain acoustic wave equation, and we minimize wavefield phase residuals through random perturbations to a 1-D vertically varying anisotropy profile. Both real and synthetic examples are presented in order to demonstrate and validate the approach. For the real data example, we processed and inverted a cross-borehole data set acquired by Vale Technology Development (Canada) Ltd. in the Eastern Deeps deposit, located in Voisey's Bay, Labrador, Canada. The inversion workflow comprises the full suite of acquisition, data processing, starting model building through traveltime tomography, simulated annealing and finally waveform tomography. Waveform tomography is a high resolution method that requires an accurate starting model. A cycle-skipping issue observed in our initial starting model was hypothesized to be due to an erroneous anisotropy model from traveltime tomography. This motivated the use of simulated annealing as a semi-global method for anisotropy estimation. We initially tested the simulated annealing approach on a synthetic data set based on the Voisey's Bay environment; these tests were successful and led to the application of the simulated annealing approach to the real data set. Similar behaviour was observed in the anisotropy models obtained through traveltime tomography in both the real and synthetic data sets, where simulated annealing produced an anisotropy model which solved the cycle-skipping issue. In the real data example, simulated annealing led to a final model that compares well with the velocities independently estimated from borehole logs. By comparing the calculated ray paths and wave paths, we attributed the failure of anisotropic traveltime tomography to the breakdown of the ray-theoretical approximation in the vicinity of strong velocity discontinuitie

Decrease in water clarity of the southern and central North Sea during the 20th century

Light in the marine environment is a key environmental variable coupling physics to marine biogeochemistry and ecology. Weak light penetration reduces light available for photosynthesis, changing energy fluxes through the marine food web. Based on published and unpublished data, this study shows that the central and southern North Sea has become significantly less clear over the second half of the 20th century. In particular, in the different regions and seasons investigated, the average Secchi depth pre-1950 decreased between 25% and 75% compared to the average Secchi depth post-1950. Consequently, in summer pre-1950, most (74%) of the sea floor in the permanently mixed area off East Anglia was within the photic zone. For the last 25+ years, changes in water clarity were more likely driven by an increase in the concentration of suspended sediments, rather than phytoplankton. We suggest that a combination of causes have contributed to this increase in suspended sediments such as changes in sea-bed communities and in weather patterns, decreased sink of sediments in estuaries, and increased coastal erosion. A predicted future increase in storminess (Beniston et al., 2007; Kovats et al., 2014) could enhance the concentration of suspended sediments in the water column and consequently lead to a further decrease in clarity, with potential impacts on phytoplankton production, CO2 fluxes, and fishery production

Effect of a Patient-Centered Phone Call by a Clinical Officer at Time of HIV Testing on Linkage to Care in Rural Kenya.

In a randomized controlled trial, we tested whether a structured, patient-centered phone call from a clinical officer after HIV testing improved linkage to/re-engagement in HIV care. Among 130 HIV-positive persons, those randomized to the phone call were significantly more likely to link to care by 7 and 30 days (P = .04)

Multiple fragmented habitat-patch use in an urban breeding passerine, the Short-toed Treecreeper

Individual responses of wild birds to fragmented habitat have rarely been studied, despite large-scale habitat fragmentation and biodiversity loss resulting from widespread urbanisation. We investigated the spatial ecology of the Short-toed Treecreeper Certhia brachydactyla, a tiny, resident, woodland passerine that has recently colonised city parks at the northern extent of its range. High resolution spatiotemporal movements of this obligate tree-living species were determined using radio telemetry within the urbanized matrix of city parks in Copenhagen, Denmark. We identified regular edge crossing behaviour, novel in woodland birds. While low numbers of individuals precluded a comprehensive characterisation of home range for this population, we were able to describe a consistent behaviour which has consequences for our understanding of animal movement in urban ecosystems. We report that treecreepers move freely, and apparently do so regularly, between isolated habitat patches. This behaviour is a possible driver of the range expansion in this species and may contribute to rapid dispersal capabilities in certain avian species, including Short-toed Treecreepers, into northern Europe. Alternatively, these behaviours might be common and/or provide an adaptive advantage for birds utilising matrix habitats, for example within urban ecosystems

Highly transparent poly(2-ethyl-2-oxazoline)-TiO2 nanocomposite coatings for the conservation of matte painted artworks

A nanocomposite coating based on TiO2 nanoparticles and poly(2-ethyl-2-oxazoline) is used as consolidant of matte painted surfaces (temperas, watercolors, modern paintings). The aim of this work is to provide advances in the conservation of these works of art, while preserving their optical appearance, in terms of colour and gloss. Fiber Optic Reflectance Spectroscopy (FORS) measurements of a painting-model (an acrylic black monochrome) treated with the nanocomposite coatings revealed that it is possible to match the optical appearance of the painted surface by tuning the amount of nanoparticles in the polymeric matrix. The requirement of retreatability of the material has been verified by removing the nanocomposite cast on the painted surface with aqueous solutions. FTIR and SEM/EDX measurements showed that almost no traces of the nanocomposite remained on the painted surface, allowing its use for the treatment of real paintings. Test were performed using a contemporary studio-model on canvas attributed to Agostino Bonalumi (1935–2013)

Acceptability and preferences for safer conception HIV prevention strategies: a qualitative study

Safer conception strategies to reduce HIV transmission risk include antiretroviral therapy (ART) for HIV-positive partners, pre-exposure prophylaxis (PrEP) for HIV-negative partners, condomless sex limited to fertile periods, and home-based self-insemination. Resistance to taking treatment or cultural concerns may limit uptake of strategies and intervention success. Understanding the acceptability and preferences between different approaches is important to optimize service delivery. Between February-July 2013, 42 adults (21 HIV-positive and 21 HIV-negative) receiving primary care at Witkoppen Health and Welfare Centre in Johannesburg, South Africa, participated in focus group discussions or in-depth interviews. Themes were analyzed using a grounded theory approach. Acceptability of antiretroviral-based (ARV) strategies varied. Concerns over side effects, ARV treatment duration, and beliefs that treatment is only for the sick were common barriers, however desperation for a child was noted as a facilitator for uptake. HIV-negative men and HIV-positive women had favorable attitudes towards self-insemination, though paternity and safety concerns were raised. Self-insemination was generally preferred over PrEP by HIV-negative men, and ARV-based strategies were preferred by couples with HIV-negative female partners, despite concerns raised about condomless sex while virally suppressed. Knowledge about the fertile window was low. A strong counselling component will be required for effective uptake and adherence to safer conception services

Drugs for treating Buruli ulcer (Mycobacterium ulcerans disease)

Background Buruli ulcer is a necrotizing cutaneous infection caused by infection with Mycobacterium ulcerans bacteria that occurs mainly in tropical and subtropical regions. The infection progresses from nodules under the skin to deep ulcers, often on the upper and lower limbs or on the face. If left undiagnosed and untreated, it can lead to lifelong disfigurement and disabilities. It is often treated with drugs and surgery. Objectives To summarize the evidence of drug treatments for treating Buruli ulcer. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (PubMed); Embase (Ovid); and LILACS (Latin American and Caribbean Health Sciences Literature; BIREME). We also searched the US National Institutes of Health Ongoing Trials Register (clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en/). All searches were run up to 19 December 2017. We also checked the reference lists of articles identified by the literature search, and contacted leading researchers in this topic area to identify any unpublished data. Selection criteria We included randomized controlled trials (RCTs) that compared antibiotic therapy to placebo or alternative therapy such as surgery, or that compared different antibiotic regimens. We also included prospective observational studies that evaluated different antibiotic regimens with or without surgery. Data collection and analysis Two review authors independently applied the inclusion criteria, extracted the data, and assessed methodological quality. We calculated the risk ratio (RR) for dichotomous data with 95% confidence intervals (CI). We assessed the certainty of the evidence using the GRADE approach. Main results We included a total of 18 studies: five RCTs involving a total of 319 participants, ranging from 12 participants to 151 participants, and 13 prospective observational studies, with 1665 participants. Studies evaluated various drugs usually in addition to surgery, and were carried out across eight countries in areas with high Buruli ulcer endemicity in West Africa and Australia. Only one RCT reported adequate methods to minimize bias. Regarding monotherapy, one RCT and one observational study evaluated clofazimine, and one RCT evaluated sulfamethoxazole/trimethoprim. All three studies had small sample sizes, and no treatment effect was demonstrated. The remaining studies examined combination therapy. Rifampicin combined with streptomycin We found one RCT and six observational studies which evaluated rifampicin combined with streptomycin for different lengths of treatment (2, 4, 8, or 12 weeks) (941 participants). The RCT did not demonstrate a difference between the drugs added to surgery compared with surgery alone for recurrence at 12 months, but was underpowered (RR 0.12, 95% CI 0.01 to 2.51; 21 participants; very low‐certainty evidence). An additional five single‐arm observational studies with 828 participants using this regimen for eight weeks with surgery (given to either all participants or to a select group) reported healing rates ranging from 84.5% to 100%, assessed between six weeks and one year. Four observational studies reported healing rates for participants who received the regimen alone without surgery, reporting healing rates ranging from 48% to 95% assessed between eight weeks and one year. Rifampicin combined with clarithromycin Two observational studies administered combined rifampicin and clarithromycin. One study evaluated the regimen alone (no surgery) for eight weeks and reported a healing rate of 50% at 12 months (30 participants). Another study evaluated the regimen administered for various durations (as determined by the clinicians, durations unspecified) with surgery and reported a healing rate of 100% at 12 months (21 participants). Rifampicin with streptomycin initially, changing to rifampicin with clarithromycin in consolidation phase One RCT evaluated this regimen (four weeks in each phase) against continuing with rifampicin and streptomycin in the consolidation phase (total eight weeks). All included participants had small lesions, and healing rates were above 90% in both groups without surgery (healing rate at 12 months RR 0.94, 95% CI 0.87 to 1.03; 151 participants; low‐certainty evidence). One single‐arm observational study evaluating the substitution of streptomycin with clarithromycin in the consolidation phase (6 weeks, total 8 weeks) without surgery given to a select group showed a healing rate of 98% at 12 months (41 participants). Novel combination therapy Two large prospective studies in Australia evaluated some novel regimens. One study evaluating rifampicin combined with either ciprofloxacin, clarithromycin, or moxifloxacin without surgery reported a healing rate of 76.5% at 12 months (132 participants). Another study evaluating combinations of two to three drugs from rifampicin, ciprofloxacin, clarithromycin, ethambutol, moxifloxacin, or amikacin with surgery reported a healing rate of 100% (90 participants). Adverse effects were reported in only three RCTs (158 participants) and eight prospective observational studies (878 participants), and were consistent with what is already known about the adverse effect profile of these drugs. Paradoxical reactions (clinical deterioration after treatment caused by enhanced immune response to M ulcerans) were evaluated in six prospective observational studies (822 participants), and the incidence of paradoxical reactions ranged from 1.9% to 26%. Authors' conclusions While the antibiotic combination treatments evaluated appear to be effective, we found insufficient evidence showing that any particular drug is more effective than another. How different sizes, lesions, and stages of the disease may contribute to healing and which kind of lesions are in need of surgery are unclear based on the included studies. Guideline development needs to consider these factors in designing practical treatment regimens. Forthcoming trials using clarithromycin with rifampicin and other trials of new regimens that also address these factors will help to identify the best regimens

embCAB Sequence Variation Among Ethambutol-Resistant Mycobacterium Tuberculosis Isolates Without embB306 Mutation

Mechanisms of resistance to ethambutol in Mycobacterium tuberculosis remain inadequately described. Although there is mounting evidence that mutations of codon 306 in embB play a key role, a significant number of phenotypically ethambutol-resistant strains do not carry mutations in this codon. Here, other mutations in the embCAB operon are suggested to be involved in resistance development