The Use of Dimethyldioxirane in Refiner Bleaching of High-Yield Pulps

In the attempt to find improved bleaching chemicals for the bleaching of high-yield pulps, dioxiranes may prove to be the solution. Unlike hydrogen peroxide, which has been introduced to a refiner environment in the past, dimethyldioxirane (DMD) does not require the use of sodium silicates. This is very beneficial due to the fact that silicates have a highly undesirable side effect of causing excessive refiner plate wear. The experimentation was constructed to determine the exact feasibility of the use of dimethyldioxirane as a refiner bleaching agent. This was completed through the comparison of the pulp strength and brightness values of refiner bleached stock using a PFI mill to simulate refiner action. Hydrogen peroxide and dimethyldioxirane generated in-situ were used as the bleaching agents. Dimethyldioxirane was found to produce a brightness increase of 8.5 points in comparison to the reference pulp. Low concentrations of DMD were found to be sufficient, with a charge of 2.0% DMD producing equivalent brightness values to higher concentrations. A 17 brightness point increase was obtained while utilizing a 2-stage refiner bleaching sequence, with the first stage being 3.0% DMD, and the second being 2.5% hydrogen peroxide without silicates

Synthetic hematocrit from virtual non-contrast images for myocardial extracellular volume evaluation with photon-counting detector CT

OBJECTIVES: To assess the accuracy of a synthetic hematocrit derived from virtual non-contrast (VNC) and virtual non-iodine images (VNI) for myocardial extracellular volume (ECV) computation with photon-counting detector computed tomography (PCD-CT). MATERIALS AND METHODS: Consecutive patients undergoing PCD-CT including a coronary CT angiography (CCTA) and a late enhancement (LE) scan and having a blood hematocrit were retrospectively included. In the first 75 patients (derivation cohort), CCTA and LE scans were reconstructed as VNI at 60, 70, and 80 keV and as VNC with quantum iterative reconstruction (QIR) strengths 2, 3, and 4. Blood pool attenuation (BP$_{mean}$) was correlated to blood hematocrit. In the next 50 patients (validation cohort), synthetic hematocrit was calculated using BP$_{mean}$. Myocardial ECV was computed using the synthetic hematocrit and compared with the ECV using the blood hematocrit as a reference. RESULTS: In the derivation cohort (49 men, mean age 79 ± 8 years), a correlation between BP$_{mean}$ and blood hematocrit ranged from poor for VNI of CCTA at 80 keV, QIR2 (R$^{2}$ = 0.12) to moderate for VNI of LE at 60 keV, QIR4; 70 keV, QIR3 and 4; and VNC of LE, QIR3 and 4 (all, R$^{2}$ = 0.58). In the validation cohort (29 men, age 75 ± 14 years), synthetic hematocrit was calculated from VNC of the LE scan, QIR3. Median ECV was 26.9% (interquartile range (IQR), 25.5%, 28.8%) using the blood hematocrit and 26.8% (IQR, 25.4%, 29.7%) using synthetic hematocrit (VNC, QIR3; mean difference, -0.2%; limits of agreement, -2.4%, 2.0%; p = 0.33). CONCLUSION: Synthetic hematocrit calculated from VNC images enables an accurate computation of myocardial ECV with PCD-CT. CLINICAL RELEVANCE STATEMENT: Virtual non-contrast images from cardiac late enhancement scans with photon-counting detector CT allow the calculation of a synthetic hematocrit, which enables accurate computation of myocardial extracellular volume. KEY POINTS: - Blood hematocrit is mandatory for conventional myocardial extracellular volume computation. - Synthetic hematocrit can be calculated from virtual non-iodine and non-contrast photon-counting detector CT images. - Synthetic hematocrit from virtual non-contrast images enables computation of the myocardial extracellular volume

Diagnostic accuracy of non-specialist versus specialist health workers in diagnosing hearing loss and ear disease in Malawi.

OBJECTIVE: To determine whether a non-specialist health worker can accurately undertake audiometry and otoscopy, the essential clinical examinations in a survey of hearing loss, instead of a highly skilled specialist (i.e. ENT or audiologist). METHODS: A clinic-based diagnostic accuracy study was conducted in Malawi. Consecutively sampled participants ≥ 18 years had their hearing tested using a validated tablet-based audiometer (hearTest) by an audiologist (gold standard), an audiology officer, a nurse and a community health worker (CHW). Otoscopy for diagnosis of ear pathologies was conducted by an ENT specialist (gold standard), an ENT clinical officer, a CHW, an ENT nurse and a general nurse. Sensitivity, specificity and kappa (κ) were calculated. 80% sensitivity, 70% specificity and kappa of 0.6 were considered adequate. RESULTS: Six hundred and seventeen participants were included. High sensitivity (>90%) and specificity (>85%) in detecting bilateral hearing loss was obtained by all non-specialists. For otoscopy, sensitivity and specificity were >80% for all non-specialists in diagnosing any pathology except for the ENT nurse. Agreement in diagnoses for the ENT clinical officer was good (κ = 0.7) in both ears. For other assessors, moderate agreement was found (κ = 0.5). CONCLUSION: A non-specialist can be trained to accurately assess hearing using mobile-based audiometry. However, accurate diagnosis of ear conditions requires at least an ENT clinical officer (or equivalent). Conducting surveys of hearing loss with non-specialists could lower costs and increase data collection, particularly in low- and middle-income countries, where ENT specialists are scarce

Distant agricultural landscapes

This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. The final publication is available at Springer via http://dx.doi.org/10.1007/s11625-014-0278-0This paper examines the relationship between the development of the dominant industrial food system and its associated global economic drivers and the environmental sustainability of agricultural landscapes. It makes the case that the growth of the global industrial food system has encouraged increasingly complex forms of “distance” that separate food both geographically and mentally from the landscapes on which it was produced. This separation between food and its originating landscape poses challenges for the ability of more localized agricultural sustainability initiatives to address some of the broader problems in the global food system. In particular, distance enables certain powerful actors to externalize ecological and social costs, which in turn makes it difficult to link specific global actors to particular biophysical and social impacts felt on local agricultural landscapes. Feedback mechanisms that normally would provide pressure for improved agricultural sustainability are weak because there is a lack of clarity regarding responsibility for outcomes. The paper provides a brief illustration of these dynamics with a closer look at increased financialization in the food system. It shows that new forms of distancing are encouraged by the growing significance of financial markets in global agrifood value chains. This dynamic has a substantial impact on food system outcomes and ultimately complicates efforts to scale up small-scale local agricultural models that are more sustainable.The Trudeau Foundation || Social Sciences and Humanities Research Council of Canad

Financial crises and the political economy of speculative bubbles

Finance has traditionally been conceptualized on the basis of what could be labelled a credit model. This model theorizes finance as a functional actor in the process of capitalist accumulation. This structural model has entertained a specific understanding of the contradictions of finance which emphasizes the imbalances in its relation to production. While the rich literature based on this template has generated important insights for understanding capitalist finance, it is debatable whether the credit model is sufficient to account for financial speculation. This article argues that the perception that speculation is essentially based on irrational optimism fails to capture what is important about recent developments of finance. New conceptual foundations are required, in order to develop a political economy of speculation which examines the way in which speculation is socially constructed, how it evolves through history and whether or not it is transforming the nature of capital accumulation