Europese miljoenen voor stamcelonderzoek bij planten

Onderzoek levert fundamentele kennis over plantengroei, relevant voor de landbouw

Differentielle Tierpsychologie: Hypo- und hyperphage Reaktionen unter Streß

no abstract availabl

A superconducting transformer system for high current cable testing

This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10 464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples

Constraints on the sources of branched tetraether membrane lipids in distal marine sediments

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are membrane lipids produced by soil bacteria and occur in near coastal marine sediments as a result of soil organic matter input. Their abundance relative to marine-derived crenarchaeol, quantified in the BIT index, generally decreases offshore. However, in distal marine sediments, low relative amounts of brGDGTs can often still be observed. Sedimentary in situ production as well as dust input have been suggested as potential, though as yet not well constrained, sources. In this study brGDGT distributions in dust were examined and compared with those in distal marine sediments. Dust was sampled along the equatorial West African coast and brGDGTs were detected in most of the samples, albeit in low abundance. Their degree of methylation and cyclisation, expressed in the MBT' (methylation index of branched tetraethers) and DC (degree of cyclisation) indices, respectively, were comparable with those for African soils, their presumed source. Comparison of DC index values for brGDGTS in global soils, Congo deep-sea river fan sediments and dust with those of distal marine sediments clearly showed, however, that distal marine sediments had significantly higher values. This distinctive distribution is suggestive of sedimentary in situ production as a source of brGDGTs in marine sediments, rather than dust input. The presence of in situ produced brGDGTs in marine sediments means that caution should be exercised when applying the MBT'–CBT palaeothermometer to sediments with low BIT index values, i.e. < 0.1, based on our dataset

Environmentally smart contracts for artists using non-fungible tokens

We propose Environmentally Smart Contracts, a new kind of smart contract for non-fungible tokens to solve the prudential-moral dilemma facing digital artists. The current proof-of-work-dominated non-fungible token environment requires artists to trade off the prudential benefits and the environmental costs of selling their art on blockchains. By fully correcting for environmental externalities, Environmentally Smart Contracts will allow artists to reap the sales benefits of non-fungible tokens without contributing to environmental degradation. Concrete steps to encourage the development of Environmentally Smart Contracts are discussed

Oral cancer trends in a single head-and-neck cancer center in the Netherlands; decline in T-stage at the time of admission

Objectives: In this study we evaluated the possible epidemiologic changes of oral cancer patients in the Netherlands between the years 1980-1984 and 2000-2004. We specifically studied the differences in male-female ratio, age, TNM-stage, site distribution, and alcohol and tobacco use. Materials and Methods: Patients from the VU University Medical Center with an oral squamous cell carcinoma of the oral cavity registered in 1980-1984 (n=200), group 1, were compared to patients registered in 2000-2004 (n=184), group 2. Trends in prevalence, site distribution, TNM-stage, alcohol and tobacco use, age and gender were studied. Results: The male-female ratio has decreased from 1.8 to 1.2. There were no differences in age between the two groups of patients. The site distribution was similar in both groups. The most commonly involved sites were the tongue and the floor of mouth. In group 2 more patients were diagnosed with a T1 tumour. There were no differences in tobacco use between the two different groups. There were much more light drinkers (0-2 drinks per day) in group 2 than in group 1, whereas there were more heavy drinkers (>4 per day) in group 1 than in group 2 (p<0.001). This was observed in both male and female patients. Conclusion: In our study there were no significant differences between the patients registered in the years 1980-1984 and 2000-2004 regarding the mean age of the patients, site distribution and smoking habits. The male-female ratio has decreased. In the recent group more patients were staged T1N0 and there was a strong decrease of the patients who were heavy drinkers. © Medicina Oral S. L

A proof-of-concept Bitter-like HTS electromagnet fabricated from a silver-infiltrated (RE)BCO ceramic bulk

A novel concept for a compact high-field magnet coil is introduced. This is based on stacking slit annular discs cut from bulk rare-earth barium cuprate ((RE)BCO) ceramic in a Bitter-like architecture. Finite-element modelling shows that a small 20 turn stack (with a total coil volume of &lt;20 cm3) is capable of generating a central bore magnetic field of &gt;2 T at 77 K and &gt;20 T at 30 K. Unlike resistive Bitter magnets, the high-temperature superconducting (HTS) Bitter stack exhibits significant non-linear field behaviour during current ramping, caused by current filling proceeding from the inner radius outwards in each HTS layer. Practical proof-of-concept for this architecture was then demonstrated through fabricating an uninsulated four-turn prototype coil stack and operating this at 77 K. A maximum central field of 0.382 T was measured at 1.2 kA, with an accompanying 6.1 W of internal heat dissipation within the coil. Strong magnetic hysteresis behaviour was observed within the prototype coil, with ≈30% of the maximum central field still remaining trapped 45 min after the current had been removed. The coil was thermally stable during a 15 min hold at 1 kA, and survived thermal cycling to room temperature without noticeable deterioration in performance. A final test-to-destruction of the coil showed that the limiting weak point in the stack was growth-sector boundaries present in the original (RE)BCO bulk