Leeftijdsbepaling van kokkels uit de Oosterschelde 1998 en 2000

Ter onderbouwing van het beleid voor de kokkelvisserij in schelpdier-arme jaren wordt sinds 1990 in opdracht van het ministerie van Landbouw, Natuurbeheer en Visserij (LNV) door het RIVO-CSO jaarlijks het kokkelbestand (Cerastoderma edule) in de Oosterschelde, de Westerschelde en de Waddenzee geïnventariseerd. De kokkelbestandsopnames worden in het voorjaar uitgevoerd. In een aantal jaren is ook een bestandsopname in het najaar uitgevoerd. Daarnaast is in 1991 door het RIVO-CSO, onafhankelijk van de surveys, een onderzoek opgezet naar de groei en sterfte van kokkelbestanden in de Oosterschelde en in de Westerschelde. Dit onderzoek is opgezet om meer inzicht te krijgen in de factoren die van invloed kunnen zijn op de ontwikkeling van kokkelbestanden

A descriptive analysis of the effect of the national COVID-19 lockdown on the workload and case mix of patients presenting to a district-level emergency centre in Cape Town, South Africa

Background. The global COVID-19 pandemic caused many countries to institute nationwide lockdowns to limit the spread of the disease.Objectives. To describe the effect of the national COVID-19 lockdown in South Africa (SA) on the workload and case mix of patients presenting to a district-level emergency centre.Methods. The electronic patient tracking and registration database at Mitchells Plain Hospital, a district-level hospital in Cape Town, was retrospectively analysed. The 5-week lockdown period (27 March - 30 April 2020) was compared with a similar period immediately before the lockdown (21 February - 26 March). A comparison was also made with corresponding time periods during 2018 and 2019. Patient demographics, characteristics, diagnoses and disposition, as well as process times, were compared.Results. A total of 26 164 emergency centre visits were analysed (8 297 in 2020, 9 726 in 2019, 8 141 in 2018). There was a reduction of 15% in overall emergency centre visits from 2019 to 2020 (non-trauma 14%, trauma 20%). A 35% decrease was seen between the 2020 lockdown period and the 5-week period before lockdown (non-trauma 33%, trauma 43%), and the reduced number of visits stayed similar throughout the lockdown period. The median age increased by 5 years during the 2020 lockdown period, along with an 8% decrease in patients aged <12 years. High-acuity patients increased by 6% and the emergency centre mortality rate increased by 1%. All process times were shorter during the lockdown period (time to triage –24%, time to consultation –56%, time to disposition decision –29%, time in the emergency centre –20%).Conclusions. The SA national COVID-19 lockdown resulted in a substantial decrease in the number of patients presenting to the emergency centre. It is yet to be seen how quickly emergency centre volumes will recover as lockdown measures are eased

Comparison of a Head-Mounted Display and a Curved Screen in a Multi-Talker Audiovisual Listening Task

Virtual audiovisual technology has matured and its use in research is widely considered. However, the technology has yet to be established for speech- and audio-related perception research. This study examined the effects of different audiovisual conditions on head yaw and gaze direction when listening to multi-talker conversations. Two immersive displays were tested, a curved screen (CS) and a head-mounted display (HMD), combined with three visual conditions (audio-only, virtual characters and video recordings). Three groups of participants were tested: seventeen young normal-hearing, eleven older normal-hearing and ten older hearing-impaired with hearing aids. Results showed that, when visual cues were not present, the participants tended to look ahead. When visual information was available, they looked at the target speaker. Significant differences between displays and visual conditions were found, pointing out that using different audiovisual setups might lead to slightly different head yaw and gaze direction. No significant differences were found between groups. An open interview showed that the CS was preferred over the HMD and that the video recordings were the favorite visual condition.Comment: 9 pages, 4 figure

Engineering substrate specificity into a promiscuous ancestral diterpene synthase

Terpene synthases are a class of enzymes that catalyse the cyclisation of linear unsaturated hydrocarbons into a plethora of cyclic structures, of which many are industrially relevant as fragrances, flavours or due to their medical properties. Despite the structural and functional diversity of their products, members of this enzyme family show a high degree of structural and functional similarity, which is why the rules defining product and substrate specificity are not fully understood. Recently, we have used ancestral sequence reconstruction to design a hypothetical molecular ancestor of spiroviolene synthase - a diterpene synthase from Streptomyces violens that converts the linear C-20 precursor geranylgeranyl pyrophosphate (GGPP) to spiroviolene1. This ancestral enzyme shares 77 % sequence identity with the modern wild-type enzyme from S. violens. Compared to the modern enzyme, the ancestral enzyme showed increased thermostability and an additional new reactivity with the shorter C-15 substrate farnesyl pyrophosphate (FPP) that the modern enzyme did not display. To the best of our knowledge, this is the first time ancestral sequence reconstruction was used on a diterpene cyclase. Based on the ancestral enzyme, a library of enzyme-variants was designed with the aim to influence the substrate specificity of the promiscuous ancestral enzyme. We identified several variants that showed substantial preference for the native substrate GGPP (modern enzyme-like), which demonstrates that the subtle GGPP-preference of the ancestral enzyme could be “evolved” to the GGPP-specific modern enzyme phenotype. Most interestingly, we were also able to identify a few variants that showed reversed substrate preference for FPP over GGPP and thus demonstrated “evolvability” of the ancestor towards the unpreferred shorter substrate. Taken together these findings suggest that the hypothesis of promiscuous evolvable ancestral enzymes might be appropriate for this member of the diterpene synthase family. Moreover, it opens up the exciting prospect of using ancestral sequence reconstruction as a tool to engineer enzyme specificity – either by introducing new desired functionalities next to an already existing one or by reprogramming existing promiscuity towards a desired substrate specificity. Please click Additional Files below to see the full abstract

Benefits of a marketing cooperative in transition agriculture: Mórakert purchasing and service co-operative

The paper analyses the potential benefits of marketing cooperatives in Hungary, employing a transaction cost economics framework. We found that the purchased quantity, the existence of contracts, flexibility and trust are the most important factors farmers consider when selling their products via a cooperative. The most striking result is that diversification has positive influences on the share of cooperatives in farmers’ sale. Furthermore, farmers with larger bargaining power have less willingness to sell their product to the cooperative. Surprisingly, asset specificity has rather negative effects on the share of cooperatives in members’ sales