Global decarbonization potential of CO2 mineralization in concrete materials.

CO2 mineralization products are often heralded as having outstanding potentials to reduce CO2-eq. emissions. However, these claims are generally undermined by incomplete consideration of the life cycle climate change impacts, material properties, supply and demand constraints, and economic viability of CO2 mineralization products. We investigate these factors in detail for ten concrete-related CO2 mineralization products to quantify their individual and global CO2-eq. emissions reduction potentials. Our results show that in 2020, 3.9 Gt of carbonatable solid materials were generated globally, with the dominant material being end-of-life cement paste in concrete and mortar (1.4 Gt y-1). All ten of the CO2 mineralization technologies investigated here reduce life cycle CO2-eq. emissions when used to substitute comparable conventional products. In 2020, the global CO2-eq. emissions reduction potential of economically competitive CO2 mineralization technologies was 0.39 Gt CO2-eq., i.e., 15% of that from cement production. This level of CO2-eq. emissions reduction is limited by the supply of end-of-life cement paste. The results also show that it is 2 to 5 times cheaper to reduce CO2-eq. emissions by producing cement from carbonated end-of-life cement paste than carbon capture and storage (CCS), demonstrating its superior decarbonization potential. On the other hand, it is currently much more expensive to reduce CO2-eq. emissions using some CO2 mineralization technologies, like carbonated normal weight aggregate production, than CCS. Technologies and policies that increase recovery of end-of-life cement paste from aged infrastructure are key to unlocking the potential of CO2 mineralization in reducing the CO2-eq. footprint of concrete materials.

The Vicious Worm education tool improves the knowledge of community health workers on Taenia solium cysticercosis in Rwanda.

The pork tapeworm Taenia solium causes human taeniasis and cysticercosis when ingested as viable cysts and eggs, respectively. Despite its high health burden in low-income countries, knowledge of the parasite in endemic areas such as Rwanda is often limited. Here, we assess whether The Vicious Worm education software can increase knowledge in endemic areas of Rwanda. A cross-sectional mixed-methods study was conducted to evaluate knowledge about T. solium among community health workers trained using the Vicious Worm education software. Knowledge was assessed before, immediately after, and four weeks after the training. The health workers perceptions of the software were analysed thematically. A total of 207 community health workers were recruited from Nyamagabe district in Southern Province, Rwanda. Participants were composed of males (33.5%) and females (66.5%), aged between 22 and 68 years, and most (71%) had only completed primary education. Knowledge of cysticercosis at baseline was low, particularly knowledge of human cysticercosis and neurocysticercosis. The overall knowledge score increased significantly after training and was maintained four weeks after the training. Overall, insufficient knowledge was associated with neurocysticercosis-related questions, which after the training, remained relatively lower compared to questions of other categories. Participants reported the software to be user-friendly and educational. Digital illiteracy and the lack of smartphones were among the critical challenges highlighted in responses. This study has shown gaps in knowledge regarding T. solium infections within rural Rwanda, particularly neurocysticercosis. Health education using the Vicious Worm education software should be considered in integrated control programs.

MRI features to aid the identification of lateral temporal bone cephaloceles.

OBJECTIVES: To evaluate ancillary MRI features which may aid the identification of lateral temporal bone cephaloceles (LTBCs). METHODS: A retrospective cohort study analysed patients with MRI evidence of surgically confirmed spontaneous LTBCs as defined by intracranial contents traversing the tegmen tympani or mastoideum. Cases were identified from radiology and surgical databases. Two observers analysed three-dimensional T 2W temporal bone and whole brain imaging according to a priori criteria by consensus, with emphasis on the relationship of any adjacent cerebrospinal fluid (CSF) cleft to the defect. The contents, location, and clinical features of the LTBCs were recorded. RESULTS: Eighteen patients (11 female, 7 male; mean age 59.3 years, age range 42-86 years) with 20 surgically confirmed spontaneous LTBCs (2 bilateral;16 unilateral) were evaluated. A temporal lobe sulcus or other CSF cleft extending to or traversing the defect was identified in 19/20 (95%) cases. Isointense CSF tympanomastoid signal was present in 41.2% cases, whilst superior semi-circular canal dehiscence was found in 40% of cephaloceles. At least two MRI features of idiopathic intracranial hypertension were seen in 38.9% patients. Cephaloceles were most commonly centred on the tegmen tympani (55%). Meningoencephaloceles were present in 95% cases. CONCLUSION: A temporal lobe sulcus or CSF cleft extending to or traversing the defect may aid the identification of LTBCs. Isointense CSF tympanomastoid signal, superior semi-circular canal dehiscence and MRI features of idiopathic intracranial hypertension are only present in under half of LTBCs. ADVANCES IN KNOWLEDGE: The study details novel ancillary MRI features of LTBCs which may aid their identification.

Effects of operational parameters on the performance of unialgal Oedogonium sp. filamentous algae nutrient scrubbers under controlled environmental conditions.

Filamentous algae nutrient scrubber (FANS) operating parameters can strongly influence algal biomass productivity and nutrient removal. However, few studies to date have investigated the effects of FANS operating parameters such as initial standing crop, harvesting frequency and influent flow rate on biomass productivity and nutrient removal performance, especially for FANS that cultivate a single species of algae. Therefore, the overall aim of this study was to investigate how operating parameters affect the biomass productivity and nutrient removal performance of Oedogonium sp. - a promising species for unialgal FANS. The initial standing crop had a significant effect on biomass productivity, with productivities being highest (8.6 ± 0.5 g DW biomass m-2day-1) when the initial standing crop was 60-70 g DW m-2. However, the daily nutrient removal rate was highest (0.47 ± 0.06 g N m-2 day-1and 1.24 ± 0.13 g P m-2 day-1) at the highest initial standing crop (100-110 DW m-2). Biomass productivity was highest with a three-day growth period, regardless of size of the initial standing crop. Therefore, a four-day harvesting interval was selected as the optimal harvesting regime to promote exponential growth and high biomass production. Influent flow rate had a significant effect on biomass productivity, which was highest (9.3 ± 1.7 g DW m-2 day-1) for the 1 L min-1 flow rate. This flow rate also gave the highest instantaneous nutrient removal rate (0.05 ± 0.02 g N m-3 and 0.14 ± 0.05 g P m-3). Current results suggest that an optimum initial standing crop of 70-80 g DW m-2, harvesting frequency of four days and influent flow rate of 1 L min-1 (16.7 L min-1 m-1 width) were optimal for Oedogonium sp. cultivated on FANS to maximize their biomass production and nutrient removal under controlled laboratory conditions. These results contribute to understanding the impacts of operating parameters on optimizing unialgal Oedogonium sp. FANS biomass production and nutrient removal performance.

Cement substitution with secondary materials can reduce annual global CO2 emissions by up to 1.3 gigatons.

Population and development megatrends will drive growth in cement production, which is already one of the most challenging-to-mitigate sources of CO2 emissions. However, availabilities of conventional secondary cementitious materials (CMs) like fly ash are declining. Here, we present detailed generation rates of secondary CMs worldwide between 2002 and 2018, showing the potential for 3.5 Gt to be generated in 2018. Maximal substitution of Portland cement clinker with these materials could have avoided up to 1.3 Gt CO2-eq. emissions (~44% of cement production and ~2.8% of anthropogenic CO2-eq. emissions) in 2018. We also show that nearly all of the highest cement producing nations can locally generate and use secondary CMs to substitute up to 50% domestic Portland cement clinker, with many countries able to potentially substitute 100% Portland cement clinker. Our results highlight the importance of pursuing regionally optimized CM mix designs and systemic approaches to decarbonizing the global CMs cycle.

Population dynamics of free-roaming dogs in two European regions and implications for population control.

Changes in free-roaming dog population size are important indicators of the effectiveness of dog population management. Assessing the effectiveness of different management methods also requires estimating the processes that change population size, such as the rates of recruitment into and removal from a population. This is one of the first studies to quantify the size, rates of recruitment and removal, and health and welfare status of free-roaming dog populations in Europe. We determined the size, dynamics, and health status of free-roaming dog populations in Pescara, Italy, and Lviv, Ukraine, over a 15-month study period. Both study populations had ongoing dog population management through catch-neuter-release and sheltering programmes. Average monthly apparent survival probability was 0.93 (95% CI 0.81-1.00) in Pescara and 0.93 (95% CI 0.84-0.99) in Lviv. An average of 7 dogs km-2 were observed in Pescara and 40 dogs km-2 in Lviv. Per capita entry probabilities varied between 0.09 and 0.20 in Pescara, and 0.12 and 0.42 in Lviv. In Lviv, detection probability was lower on weekdays (odds ratio: 0.74, 95% CI 0.53-0.96) and higher on market days (odds ratio: 2.58, 95% CI 1.28-4.14), and apparent survival probability was lower in males (odds ratio: 0.25, 95% CI 0.03-0.59). Few juveniles were observed in the study populations, indicating that recruitment may be occurring by movement between dog subpopulations (e.g. from local owned or neighbouring free-roaming dog populations), with important consequences for population control. This study provides important data for planning effective dog population management and for informing population and infectious disease modelling.

Resource requirements for ecosystem conservation: A combined industrial and natural ecology approach to quantifying natural capital use in nature.

Socioeconomic demand for natural capital is causing catastrophic losses of biodiversity and ecosystem functionality, most notably in regions where socioeconomic-and eco-systems compete for natural capital, e.g., energy (animal or plant matter). However, a poor quantitative understanding of what natural capital is needed to support biodiversity in ecosystems, while at the same time satisfy human development needs-those associated with human development within socioeconomic systems-undermines our ability to sustainably manage global stocks of natural capital. Here we describe a novel concept and accompanying methodology (relating the adult body mass of terrestrial species to their requirements for land area, water, and energy) to quantify the natural capital needed to support terrestrial species within ecosystems, analogous to how natural capital use by humans is quantified in a socioeconomic context. We apply this methodology to quantify the amount of natural capital needed to support species observed using a specific surveyed site in Scotland. We find that the site can support a larger assemblage of species than those observed using the site; a primary aim of the rewilding project taking place there. This method conceptualises, for the first time, a comprehensive "dual-system" approach: modelling natural capital use in socioeconomic-and eco-systems simultaneously. It can facilitate the management of natural capital at the global scale, and in both the conservation and creation (e.g., rewilding) of biodiversity within managed ecosystems, representing an advancement in determining what socioeconomic trade-offs are needed to achieve contemporary conservation targets alongside ongoing human development.

Assessing the impact of free-roaming dog population management through systems modelling.

Free-roaming dogs can present significant challenges to public health, wildlife conservation, and livestock production. Free-roaming dogs may also experience poor health and welfare. Dog population management is widely conducted to mitigate these issues. To ensure efficient use of resources, it is critical that effective, cost-efficient, and high-welfare strategies are identified. The dog population comprises distinct subpopulations characterised by their restriction status and level of ownership, but the assessment of dog population management often fails to consider the impact of the interaction between subpopulations on management success. We present a system dynamics model that incorporates an interactive and dynamic system of dog subpopulations. Methods incorporating both fertility control and responsible ownership interventions (leading to a reduction in abandonment and roaming of owned dogs, and an increase in shelter adoptions) have the greatest potential to reduce free-roaming dog population sizes over longer periods of time, whilst being cost-effective and improving overall welfare. We suggest that future management should be applied at high levels of coverage and should target all sources of population increase, such as abandonment, births, and owners of free-roaming dogs, to ensure effective and cost-efficient reduction in free-roaming dog numbers.

Cost analysis of a watch-and-wait approach in patients with a complete clinical response to chemoradiotherapy for rectal cancer.

BACKGROUND: There is increasing interest in the watch-and-wait approach for patients with rectal cancer who have had a complete clinical response following neoadjuvant long course chemoradiotherapy. This study is a cost analysis of expenditure on patients in the watch-and-wait program versus patients who underwent standard rectal resection followed by routine surveillance. METHODS: Data were prospectively collated and retrospectively analysed in all patients who presented with rectal cancer from January 2016 to January 2018 at Sir Charles Gairdner Hospital, Perth, Western Australia. Software developed by the North Metropolitan Health Service was used to capture comprehensive data to calculate the in-hospital expenditure for an individual patient throughout their treatment journey. RESULTS: For a patient enrolled in the watch-and-wait pathway, the total cost of surveillance over a 5-year period was $45 246. This was compared with the cost of an ultra-low anterior resection/loop ileostomy/closure of loop and routine postoperative surveillance which came to a total of $87 473. While a patient who had an abdominoperineal resection followed by routine 5-year surveillance had an expenditure of $82 290. CONCLUSION: There is growing evidence that the watch-and-wait strategy is a valid management option. In the cost-conscious environment of the current health care system, the watch-and-wait pathway is a cost-effective and economically advantage treatment.

The influences of the COVID-19 pandemic on sustainable consumption: an international study.

Background: Sustainable production and consumption are two important issues, which mutually interact. Whereas individuals have little direct influence on the former, they can play a key role on the latter. This paper describes the subject matter of sustainable consumption and outlines its key features. It also describes some international initiatives in this field. Results: By means of an international survey, the study explores the emphasis given to sustainable consumption during the second wave of the COVID-19 pandemic, and the degree of preparedness in individuals to engage in the purchase of green and sustainably manufactured products. The main results indicate that the pandemic offered an opportunity to promote sustainable consumption; nevertheless, the pandemic alone cannot be regarded as a 'game changer' in this topic. Conclusions: Apart from an online survey with responses from 31 countries, which makes it one of the most representative studies on the topic, a logit model was used to analyse the main variables that affect the probability of pro-environmental consumption behaviour because of the COVID-19 pandemic. The paper lists some of the technological and social innovations that may be needed, so as to guide more sustainable consumption patterns in a post-pandemic world.

Association of Fig Pollinating Wasps and Fig Nematodes inside Male and Female Figs of a Dioecious Fig Tree in Sumatra, Indonesia.

Nematodes can grow within the inflorescences of many fig trees (Ficus spp., Moraceae); however, the feeding behaviour of most nematodes is not known. Fig pollinating wasps (Hymenoptera: Agaonidae) transfer nematodes into young figs upon the wasps' entry into the figs to deposit their eggs. Most Asian fig trees, however, are functionally dioecious, and the pollinating wasps that enter female figs are unable to reproduce. They fail to produce the offspring required to carry the new generations of nematodes. We examined whether female figs of F. hispida can nonetheless support the development of phoretic nematode populations. Nematodes were extracted from male and female figs sampled in Sumatra, Indonesia, to compare the growth of their populations within the figs. We found three species of nematodes that grew within figs of male and female trees of F. hispida: Ficophagus cf. centerae (Aphelenchoididae), Martininema baculum (Aphelenchoididae) and Caenorhabditis sp (Rhabditidae). The latter species (Caenorhabditis sp.) has never been reported to be associated with F. hispida before. Nematode populations peaked at around 120-140 individuals in both sexes of figs, at the time when a succeeding generation of adult fig wasps appeared within male figs. The female figs could support the growth and reproduction of the three nematodes species; however, the absence of vectors meant that female figs remained as traps from which there could be no escape.

Effect of algal contact time and horizontal water velocity on the performance of Filamentous Algal Nutrient Scrubbers (FANS).

We investigated the effect of algal contact time (ACT) and horizontal water velocity (HWV) on the performance of pilot-scale Filamentous Algae Nutrient Scrubbers (FANS) treating river water during the NZ summer. The FANS floways were seeded with a mixture of four New Zealand native filamentous algal species (Oedogonium sp., Cladophora sp., Rhizoclonium sp., and Spirogyra sp.) and allowed to establish over one month. River water was pumped onto the top of each FANS at different flow rates (2, 4 or 8 L min-1) to give ACTs from 0.6 to 10.1 min depending on FANS length (6-24 m) and HWV from 0.04 to 0.16 m s-1. FANS inflow and final outflows were monitored three times a week for nitrate and DRP concentrations and FANS algal biomass was harvested weekly. Average biomass productivity was significantly higher on the FANS with shorter ACT. For example, biomass productivity of the 24 m length FANS with 2.5 min ACT were 67% higher (11.2 g DW m-2 d-1) than that with four times the ACT (10.1 min). Irrespective of the HWV the biomass productivity declined down the length of the floways (with longer ACT) and the decline was greater at lower HWV. The decreased biomass productivity at lower HWV (and/or higher ACT) was likely attributable to the daytime carbon limitation of photosynthesis (at pH > 9.5) and heat stress with elevated daytime water temperature (at >30 °C). Despite the short ACT (<10.1 min) the single pass pilot-scale FANS effectively removed both nitrate-N and DRP from the river water, with >35% removal of both NO3-N (from 0.49 to <0.32 mg N L-1) and DRP (from 0.14 to <0.09 mg P L-1). Both the nitrogen and phosphorus content of the harvested algal biomass were unaffected by both HWV and ACT and typical (N: ∼2.0%; P: 0.2-0.3%) of the literature values (N: 1.5-3.0%; P: 0.15-0.32%). Compared with constructed wetland nutrient removal (0.1 g N m-2 d-1; 0.08 g P m-2 d-1), the FANS achieved up to 2.5-fold higher nitrogen removal (0.24 N m-2 d-1) through algal nitrogen assimilation followed by subsequent algal harvest and up to 4-fold higher phosphorus removal (0.34 g P m-2 d-1) through a combination of algal phosphorus assimilation and some P-precipitation under photosynthesis-mediated elevated daytime pH levels (pH > 9.0). This research indicates that FANS have the potential to require less than half the land area of constructed wetlands for the same level of nitrogen removal and that they require only a few weeks to establish to achieve full performance. Moreover, FANS have the further benefit of resource recovery for beneficial re-use of harvested algal biomass for animal feed, fertiliser, or biofuel.

Negotiating Stakeholder Relationships in a Regional Circular Economy: Discourse Analysis of Multi-scalar Policies and Company Statements from the North of England.

Circular economy (CE) literature discusses the need for cooperation between different stakeholders to promote a CE; there is also an assumption regarding the benefits of loop closing on a local or regional scale. However, the potentially conflicting priorities, understandings, and expectations of the stakeholders involved have not been sufficiently addressed. Regional (or local) authorities have a responsibility to promote prosperity for stakeholders in their administrative region, within the constraints of national policy; conversely companies can have financial imperatives associated with stakeholders who may be globally distributed. Evidence of these conflicting priorities, the various positions stakeholder take, and their expectations of each other can be seen in the language choices regional actors make in their public-facing policy and report documents. The aim of the paper is to consider the challenges for creating a regional-scale CE that might arise from the differing priorities and values of companies and public agencies relating to specific places. It uses discourse analysis (including critical approaches) to examine how policy and business documents represent the stakeholders of the CE, their place in it, their priorities, and, importantly, the relationship between CE actors, focusing on the case of North Humberside on the North East coast of England. The plans set out in these reports are designed for external stakeholders and allow us to gain an insight into company and policy thinking in relation to CE developments in the coming years, including how they view each other's roles. Findings indicate a shared motivation across scales and sectors for the CE as a means towards sustainable growth within which business plays a central role. However, there is a critical double disjuncture between different visions for implementation. First, between policy scales, a regional-scale CE is prioritised by regional policymakers, who have an interest in economic advantage being tied to a specific place and call for national scale support for their actions. Second, between regional policymakers and business, companies focus on their own internal operations and potential supply chain collaborations, with little attention given to the regional scale. This can be seen in the way organisations represent the actors of a nascent CE differently. In addition, a hegemonic business-focused growth discourse excludes other visions of the CE; the public are relegated to a passive role primarily as consumers and recipients of under-specified "opportunities" of wealth creation. CE theorisations need to incorporate and address these critical perspectives in order to support the development of strategies to overcome them.

131I-GD2-ch14.18 Scintigraphy to Evaluate Option for Radioimmunotherapy in Patients with Advanced Tumors.

The tumor-selective ganglioside antigene GD2 is frequently expressed on neuroblastomas and to a lesser extent on sarcomas and neuroendocrine tumors. The aim of our study was to evaluate the tumor targeting and biodistribution of 131I-labeled chimeric GD2-antibody clone 14/18 (131I-GD2-ch14.18) in patients with late-stage disease in order to identify eligibility for radioimmunotherapy. Methods: Twenty patients (neuroblastoma, n = 9; sarcoma, n = 9; pheochromocytoma, n = 1; and neuroendocrine tumor, n = 1) were involved in this study. A 21- to 131-MBq dose (1-2 MBq/kg) of 131I-GD2-ch14.18 (0.5-1.0 mg) was injected intravenously. Planar scintigraphy was performed within 1 h from injection (day 0) and on days 1, 2, 3, and 6 or 7 to analyze tumor uptake and tracer biodistribution. Serial blood samples were collected in 4 individuals. Absorbed dose to tumor lesions and organs was calculated using OLINDA software. Results: The tumor-targeting rate on a per-patient base was 65% (13/20), with 6 of 9 neuroblastomas showing uptake of 131I-GD2-ch14.18. Tumor lesions showed maximum uptake at 20-64 h after injection (effective half-life in tumors, 33-192 h). The tumor-absorbed dose varied between 0.52 and 30.2 mGy/MBq (median, 9.08 mGy/MBq; n = 13). Visual analysis showed prominent blood-pool activity up to day 2 or 3 after injection. No pronounced uptake was observed in the bone marrow compartment or in the kidneys. Bone marrow dose was calculated at 0.09-0.18 mGy/MBq (median, 0.12 mGy/MBq), whereas blood dose was 1.1-4.7 mGy/MBq. Two patients (1 neuroblastoma and 1 pheochromocytoma) with particularly high tumor uptake underwent radioimmunotherapy using 2.3 and 2.9 GBq of 131I-GD2-ch14.18, both achieving stable disease. Overall survival was 17 and 6 mo, respectively. Conclusion:131I-GD2-ch14.18 is cleared slowly from blood, not resulting in good tumor-to-background contrast until 2 d after application. With acceptable red marrow and organ dose, radioimmunotherapy is an option for patients with high tumor uptake. However, because of the variable GD2 expression, the decision should depend on pretherapeutic dosimetry.

Making the most of your pollinators: An epiphytic fig tree encourages its pollinators to roam between figs.

Ficus species are characterized by their unusual enclosed inflorescences (figs) and their relationship with obligate pollinator fig wasps (Agaonidae). Fig trees have a variety of growth forms, but true epiphytes are rare, and one example is Ficus deltoidea of Southeast Asia. Presumably as an adaptation to epiphytism, inflorescence design in this species is exceptional, with very few flowers in female (seed-producing) figs and unusually large seeds. Figs on male (pollinator offspring-generating) trees have many more flowers. Many fig wasps pollinate one fig each, but because of the low number of flowers per fig, efficient utilization by F. deltoidea's pollinators depends on pollinators entering several female figs. We hypothesized that it is in the interest of the plants to allow pollinators to re-emerge from figs on both male and female trees and that selection favors pollinator roaming because it increases their own reproductive success. Our manipulations of Blastophaga sp. pollinators in a Malaysian oil palm plantation confirmed that individual pollinators do routinely enter several figs of both sexes. Entering additional figs generated more seeds per pollinator on female trees and more pollinator offspring on male trees. Offspring sex ratios in subsequently entered figs were often less female-biased than in the first figs they entered, which reduced their immediate value to male trees because only female offspring carry their pollen. Small numbers of large seeds in female figs of epiphytic F. deltoidea may reflect constraints on overall female fig size, because pollinator exploitation depends on mutual mimicry between male and female figs.

Log Mean Divisia Index Decomposition Analysis of the Demand for Building Materials: Application to Concrete, Dwellings, and the U.K.

Dwellings are material intensive products. To date, material use in dwellings has been investigated mainly using economic (exogenous) or dwelling (endogenous) drivers, with few studies comprehensively combining both. For the first time, we identify a comprehensive set of such drivers of demand for building materials and analyze them using the logarithmic mean divisia index (LMDI) method. We combine the LMDI method, the concept of dynamic material flow analysis, and physical and monetary flows to decompose the demand for building materials into the following six effects: material intensity, floor area shape, dwelling type, dwelling intensity, economic output, and population. We analyze these six effects on demand for concrete in new dwellings in the U.K. from 1951 to 2014, classified into six dwelling types and four subregions. Of these six effects, the material intensity effect is the most important, overall contributing to increasing concrete demand by +79 Mt from 1950 to 2014, while the dwelling intensity effect plays an opposite role, overall reducing concrete demand from 1950 to 2014 by -56 Mt. The economic output effect is also significant (+38 Mt from 1950 to 2014). A comparative analysis of the six effects in the four U.K. nations reveals that most of the effects arise from England, while the other nations have minor effects due to their smaller populations. Our results show that changes to the demand for concrete in the U.K. fluctuate and have mainly remained between ±30 Mt year-2 from 1950 to 2014, and thus the inflows of concrete into the in-use stock of dwellings have experienced neither entirely increasing or decreasing trends during this period. This study contributes to understanding changes in resource demand due to social, economic, and technological factors and thus improves the capability to reliably and quantitatively model the use of materials in the built environment.

Comparison of faecal indicator and viral pathogen light and dark disinfection mechanisms in wastewater treatment pond mesocosms.

This study compared light and dark disinfection of faecal bacteria/viral indicator organisms (E. coli and MS2 (fRNA) bacteriophage) and human viruses (Echovirus and Norovirus) in Wastewater Treatment Pond (WTP) mesocosms. Stirred pond mesocosms were operated in either outdoor sunlight-exposed or laboratory dark conditions in two experiments during the austral summer. To investigate wavelength-dependence of sunlight disinfection, three optical filters were used: (1) polyethylene film (light control: transmitting all solar UV and visible wavelengths), (2) acrylic (removing most UVB <315 nm), and (3) polycarbonate (removing both UVB and UVA <400 nm). To assess different dark disinfection processes WTP effluent was treated before spiking with target microbes, by (a) 0.22 µm filtration to remove all but colloidal particles, (b) 0.22 µm filtration followed by heat treatment to destroy enzymes, and (c) addition of Cytochalasin B to supress protozoan grazing. Microbiological stocks containing E. coli, MS2 phage, Echovirus, and Norovirus were spiked into each mesocosm 10 min before the experiments commenced. The light control exposed to all sunlight wavelengths achieved >5-log E. coli and MS2 phage removal (from ~1.0 × 106 to <1 PFU/mL) within 3 h compared with up to 6 h in UV-filtered mesocosms. This result confirms that UVB contributes to inactivation of E. coli and viruses by direct sunlight inactivation. However, the very high attenuation with depth of UVB in WTP water (99% removal in the top 8 cm) suggests that UVB disinfection may be less important than other removal processes averaged over time and full-scale pond depth. Dark removal was appreciably slower than sunlight-mediated inactivation. The dark control typically achieved higher removal of E. coli and viruses than the 0.22 µm filtered (dark) mesocosms. This result suggests that adsorption of E. coli and viruses to WTP particles (e.g., algae and bacteria bio-flocs) is an important mechanism of dark disinfection, while bacteria and virus characteristics (e.g. surface charge) and environmental conditions can influence dark disinfection processes.

Using a Value Chain Approach to Map the Pig Production System in Rwanda, Its Governance, and Sanitary Risks.

Rwanda has a fast growing pig production sector projected to continue expansion, due to rising local and regional demand. We undertook a value chain analysis to establish the flows of pigs and pork in Rwanda and the roles of various actors involved, and to understand governance and sanitary risks in the value chain. Cross-sectional qualitative data were collected through focus group discussions and key informant interviews with farmers, brokers, butchers, abattoir managers, and veterinarians. Data were collected on pig production methods and inputs, the source and destination of live and slaughtered pigs, value-adding infrastructures (abattoirs and processing factories), the people involved and interactions between them, governance, and challenges. Pig production in Rwanda is dominated by smallholders, mainly as a source of supplementary income and secondarily for manure. Emerging medium-sized and large pig farms were also identified, located mainly around urban areas. Live pig markets are the main mechanism allowing various actors to buy/sell pigs. Brokers have an important role in pig transactions: they are key in setting prices at markets, examining pigs for disease, organising the supply of pigs for abattoirs and for export. Only a few formal pig abattoirs were identified, which mainly supply to pork processing factories based in Kigali and/or export to customers. Local consumers rely on informal slaughtering at farm or bar/restaurant backyards, with irregular veterinary inspection. Formal abattoirs were attended by a veterinary inspector, however a lack of record keeping was noted. Sanitary risks identified were a lack of biosecurity throughout the chain and poor hygiene at slaughter places. Lingual palpation was practised in pig markets to identify cysticercosis infection, however cyst-positive pigs were not destroyed, but were sold for reduced prices in the same market or later informally sold by the owner. There are few veterinarians attending farms, with most services provided by less qualified technicians or self-treatment of pigs by farmers. Overall, this production system is characterised by a high degree of informality at all nodes, combined with the rapid growth trajectory in the sector. These findings provide a basis to plan interventions tailored to vulnerabilities identified in the Rwanda pig value chain.