Population dynamics of free-swimming Annelida in four Dutch wastewater treatment plants in relation to process characteristics

Free-swimming Annelida occasionally occur in very high densities in WWTPs (WasteWater Treatment Plants) and are nowadays applied for waste sludge reduction, but their growth is uncontrollable. In order to get more insight in the population dynamics of these free-swimming Annelida, and relate their presence to process characteristics, nine ATs (Aeration Tanks) of four Dutch WWTPs were regularly sampled over a 2.5-year period. For each species, peak periods in worm population growth were defined and population doubling times and half-lives calculated. Peak periods and doubling times were compared to those in natural systems. Process characteristics were obtained from the plant operators and related to the worm populations by multivariate analysis for the first time in large-scale WWTPs. The species composition in the WWTPs was limited and the most abundant free-swimming Annelida were in decreasing order Nais spp., Aeolosoma hemprichi, Pristina aequiseta, Aeolosoma variegatum, Chaetogaster diastrophus, and Aeolosoma tenebrarum.This latter species had never been found before in WWTPs. Worm absence sometimes coincided with the presence of anoxic zones, but this was possibly overcome by higher temperatures in the WWTPs. Worms were present all year round, even in winter, but no yearly recurrences of population peaks were observed, probably as a result of stable food supply and temperature, and the lack of predation in the WWTPs. Peak periods were similar between the ATs of each WWTP. The duration of the peak periods was on average 2¿3 months for each species and the population doubling times in the peak periods were short (on average 2¿6 days), which also corresponds to a stable favorable environment. The disappearance of worm populations from the WWTPs was presumably caused by declining asexual reproduction and subsequent removal with the waste sludge. Multivariate analysis indicated that 36% of the variability in worm populations was due to spatial and temporal patterns only. In addition, no more than 4% of the variability in worm populations was related to variations in process characteristics only and worm presence was usually associated with better sludge settleability. In conclusion, our data from large-scale WWTPs suggest that growth of free-swimming Annelida still seems uncontrollable and that their effects on treatment processes are unclear, which makes stable application in wastewater treatment for sludge reduction difficult

Maurer-Cartan moduli and models for function spaces

We set up a formalism of Maurer-Cartan moduli sets for L-infinity algebras and associated twistings based on the closed model category structure on formal differential graded algebras (a.k.a. differential graded coalgebras). Among other things this formalism allows us to give a compact and manifestly homotopy invariant treatment of Chevalley-Eilenberg and Harrison cohomology. We apply the developed technology to construct rational homotopy models for function spaces.Comment: 22 pages. This version, which will appear in Advances in Mathematics, contains various technical corrections and updated bibliograph

Teelt van herfstchrysanten

Mét de toegenomen belangstelling voor de teelt van snijbloemen in het algemeen, is ook de interesse voor de teelt van herfstchrysanten toegenomen. En ook nu is deze teelt favoriet als nateelt op tal van groentebedrijven. Er is echter in de loop der jaren veel veranderd; ook met betrekking tot de teelt van herfstchrysanten. De mogelijkheden in teelttechnisch opzicht zijn belangrijk vergroot, maar ook de eisen voor een goede kwaliteit zijn verscherpt. Deze teelthandleiding geeft onder andere informatie over de economische aspecten, de kasteelt, arbeid, teeltmethoden, gewasbescherming en bemesting

Outsourcing the Management of Reusable Medical Devices in a Chain-Wide Care Setting:Mixed Methods Feasibility Study

BACKGROUND: Managing reusable medical devices incurs substantial health care costs and complexity, particularly in integrated care settings. This complexity hampers care quality, safety, and costs. Studying logistical innovations within integrated care can provide insights to medical devices use among staff effectively.OBJECTIVE: This study aimed to establish the feasibility of a logistical intervention through outsourcing and a web portal. The goal was to provide insights into users' acceptability of the intervention, on whether the intervention was successfully implemented, and on the intervention's preliminary efficacy, thus benefiting practitioners and researchers.METHODS: This paper presents a mixed methods feasibility study at a large chain-wide health care provider in the Netherlands. The intervention entailed outsourcing noncritical reusable medical devices and introducing a web portal for device management. A questionnaire gauged perceived ordering and delivery times, satisfaction with the ordering and delivery process, compliance with safety and hygiene certification, and effects on the care delivery process. Qualitative data in the form of observations, documentation, and interviews were used to identify implementing challenges. Using on-site stocktaking and data from information systems, we analyzed the utilization, costs, and rental time of medical devices before and after the intervention for wheelchairs and anti-pressure ulcer mattresses.RESULTS: Looking at the acceptability of the intervention, a high user satisfaction with the ordering and delivery process was reported (rated on a 5-point Likert scale). With respect to preliminary efficacy, we noted a reduction in the utilization of wheelchairs (on average, 1106, SD 106 fewer utilization d/mo), and a halted increase in the utilization of anti-pressure ulcer mattresses. In addition, nurses who used the web portal reported shorter ordering times for wheelchairs (-2.7 min) and anti-pressure ulcer mattresses (-3.1 min), as well as shorter delivery times for wheelchairs (-0.5 d). Moreover, an increase in device certification was reported (average score of 1.9, SD 1.0), indicating higher levels of safety and hygiene standards. In theory, these improvements should translate into better outcomes in terms of costs and the quality of care. However, we were unable to establish a reduction in total care costs or a reduced rental time per device. Furthermore, respondents did not identify improvements in safety or the quality of care. Although implementation challenges related to the diverse supply base and complexities with different care financers were observed, the overall implementation of the intervention was considered successful.CONCLUSIONS: This study confirms the feasibility of our intervention, in terms of acceptability, implementation success, and preliminary efficacy. The integrated management of medical devices should enable a reduction in costs, required devices, and material waste, as well as higher quality care. However, several challenges remain related to the implementation of such interventions.</p

Moving beyond the nature-based solutions discourse: introducing nature-based thinking

Suites of concepts and approaches have been launched during recent years to promote urban nature and greener cities. However, it is doubtable whether tinkering within the current economic and political system can provide adequate solutions. Nature-based Solutions can be seen as a new conceptual approach to the human-ecological connection, and as an outcome of an evolutionary development of socio-ecological concepts. In this Communication, we argue for drawing up inspiration by nature as an outset for the development of more sustainable and inclusive cities, balancing anthropocentric and ecocentric values and acknowledging the importance of the social and governance dimensions in a more balanced socio-ecological perspective. We call this approach Nature-based Thinking

Fatty Acid-Derived Biofuels and Chemicals Production in Saccharomyces cerevisiae

Volatile energy costs and environmental concerns have spurred interest in the development of alternative, renewable, sustainable and cost-effective energy resources. Advanced biofuels have potential to replace fossil fuels in supporting high-power demanding machinery such as aircrafts and trucks. Microbial biosynthesis is generally considered as an environmental friendly refinery process, and fatty acid biosynthesis is an attractive route to synthesize chemicals and especially drop-in biofuels due to the high degree of reduction of fatty acids. The robustness and excellent accessibility to molecular genetics make the yeast S. cerevisiae a suitable host for the production of biofuels, chemicals and pharmaceuticals, and recent advances in metabolic engineering as well as systems and synthetic biology allow us to engineer the yeast fatty acid metabolism and modification pathways for production of advanced biofuels and chemicals