Invertible Orientation Scores of 3D Images

The enhancement and detection of elongated structures in noisy image data is relevant for many biomedical applications. To handle complex crossing structures in 2D images, 2D orientation scores were introduced, which already showed their use in a variety of applications. Here we extend this work to 3D orientation scores. First, we construct the orientation score from a given dataset, which is achieved by an invertible coherent state type of transform. For this transformation we introduce 3D versions of the 2D cake-wavelets, which are complex wavelets that can simultaneously detect oriented structures and oriented edges. For efficient implementation of the different steps in the wavelet creation we use a spherical harmonic transform. Finally, we show some first results of practical applications of 3D orientation scores.Comment: ssvm 2015 published version in LNCS contains a mistake (a switch notation spherical angles) that is corrected in this arxiv versio

Stimuli-responsive behavior of PNiPAm microgels under interfacial confinement

The volume phase transition of microgels is one of the most paradigmatic examples of stimuli-responsiveness, enabling a collapse from a highly swollen microgel state into a densely coiled state by an external stimulus. Although well characterized in bulk, it remains unclear how the phase transition is affected by the presence of a confining interface. Here, we demonstrate that the temperature-induced volume phase transition of poly(N-isopropylacrylamide) microgels, conventionally considered an intrinsic molecular property of the polymer, is in fact largely suppressed when the microgel is adsorbed to an air/liquid interface. We further observe a hysteresis in core morphology and interfacial pressure between heating and cooling cycles. Our results, supported by molecular dynamics simulations, reveal that the dangling polymer chains of microgel particles, spread at the interface under the influence of surface tension, do not undergo any volume phase transition, demonstrating that the balance in free energy responsible for the volume phase transition is fundamentally altered by interfacial confinement. These results imply that important technological properties of such systems, including the temperature-induced destabilization of emulsions does not occur via a decrease in interfacial coverage of the microgels

Doubling of Microalgae Productivity by Oxygen Balanced Mixotrophy

Microalgae productivity was doubled by designing an innovative mixotrophic cultivation strategy that does not require gas-liquid transfer of oxygen or carbon dioxide. Chlorella sorokiniana SAG 211/8K was cultivated under continuous operation in a 2 L stirred-tank photobioreactor redesigned so that respiratory oxygen consumption was controlled by tuning the acetic acid supply. In this mixotrophic setup, the reactor was first operated with aeration and no net oxygen production was measured at a fixed acetic acid supply rate. Then, the aeration was stopped and the acetic acid supply rate was automatically regulated to maintain a constant dissolved oxygen level using process control software. Respiratory oxygen consumption was balanced by phototrophic oxygen production, and the reactor was operated without any gas-liquid exchange. The carbon dioxide required for photosynthesis was completely provided by the aerobic conversion of acetic acid. Under this condition, the biomass/substrate yield was 0.94 C-molx·C-molS -1. Under chemostat conditions, both reactor productivity and algal biomass concentration were doubled in comparison to a photoautotrophic reference culture. Mixotrophic cultivation did not affect the photosystem II maximum quantum yield (Fv/Fm) and the average-dry-weight-specific optical cross section of the microalgal cells. Only light absorption by chlorophylls over carotenoids decreased by 9% in the mixotrophic culture in comparison to the photoautotrophic reference. Our results demonstrate that photoautotrophic and chemoorganotrophic metabolism operate concurrently and that the overall yield is the sum of the two metabolic modes. At the expense of supplying an organic carbon source, photobioreactor productivity can be doubled while avoiding energy intensive aeration.</p

Oxygen Balanced Mixotrophy under Day-Night Cycles

Using sunlight to fuel photosynthesis exposes microalgae to day–night cycles. Under day–night cycles microalgae tend to synchronize their metabolism by optimizing light utilization during daytime. During night storage compounds are consumed, leading to biomass losses and demand of O2. We investigated “oxygen balanced” mixotrophy under 14:10 day/night cycles. In this mixotrophic setup, photosynthetic O2 production was balanced by respiratory oxygen consumption and CO2 required for photosynthesis was provided by aerobic conversion of acetic acid. This strategy allowed operation of the reactor without any gas–liquid exchange during daytime. Under these conditions Chlorella sorokiniana SAG 211/8K converted 96% of the substrate into biomass. Mixotrophic cultivation did not affect the photosystem II maximum quantum yield (Fv/Fm) or pigment contents of the microalgal cells. Mixotrophic biomass contained 50% w/w of protein and 7.3 mg g–1 of lutein. Acetic acid feeding was discontinued at night and aeration initiated. Respiration was monitored by online off-gas analysis and O2 consumption and CO2 production rates were determined. Biomass night losses were around 7% on carbon basis with no significant difference between mixotrophic and photoautotrophic cultures. Over 24 h, the mixotrophic culture required 61 times less gaseous substrate and its biomass productivity was doubled compared to the photoautotrophic counterpart.publishedVersionPaid Open Acces

Publiek – private samenwerking bij combinatie projecten

Publiek-private samenwerking (PPS) krijgt veel aandacht als wijze van uitvoering van projecten waarin investeringen in infrastructuur (bijvoorbeeld in een station voor de hogesnelheidslijn) gecombineerd worden met stedelijke vernieuwing en investeringen in vastgoed. Het gaat om zogenaamde Combinatieprojecten. Doel van dit onderzoek is bij te dragen aan inzicht in de voorwaarden waaronder de mogelijke voordelen van PPS bij Combinatieprojecten zijn te realiseren. De focus hierbij is hoe publieke belangen het best gerealiseerd kunnen worden. We richten ons daartoe op het Rijk en de gemeenten. Deze keuze impliceert geenszins dat de problematiek benaderd wordt vanuit het idee dat het de ´goedwillende overheid´ tegen de ´gehaaide private partijen´ is. De doelstelling van private partijen is in de regel overzichtelijk: het maximaliseren van winst. Daartegenover staat een complexe verzameling mogelijk tegengestelde publieke belangen. De vraag is hoe de kracht van private partijen benut kan worden om die complexe verzameling publieke doelen te realiseren. Daarbij liggen de kansen van PPS vooral in een hoger maatschappelijk rendement door uitruil van prestaties en een betere risicoverdeling tussen de partijen. De risico's van PPS zitten vooral in de afhankelijkheid van andere partijen. De twee vragen die in dit onderzoek centraal staan zijn: Welke afwegingen zijn voor het Rijk en de gemeenten van belang bij het kiezen voor PPS bij Combinatieprojecten? Gegeven een keuze voor PPS, welke factoren dragen bij tot coöperatief gedrag van alle betrokken partijen in de diverse fasen van een Combinatieproject

Calorimetry and thermodynamic aspects of heterotrophic, mixotrophic, and phototrophic growth

A simple stoichiometric model is proposed linking the biomass yield to the enthalpy and Gibbs energy changes in chemo-heterotrophic, mixotrophic, and photo-autotrophic microbial growth. A comparison with calorimetric experiments on the algae Chlorella vulgaris and Chlorella sorokiniana confirmed the trends but revealed large calorimetric measurement inaccuracies. The calorimetric data on purely photo-autotrophic growth was, however, in fair agreement with calculations. The thermodynamic characteristics of photosynthetic growth, including an estimation of the Gibbs energy dissipation, are compared with similar data for chemotrophic microbe

D4.21 – Final course evaluation report

Final report on iterative evaluations of the web2jobs training.The web2jobs project has been funded with support from the European Commission (Key Activity 3 / Multilateral Projects. Project No: 543145-LLP-1-2013-1-UK-KA3-KA3MP)

Productivity of Chlorella sorokiniana in a short light-path (SLP) panel photobioreactor under high irradiance

Maximal productivity of a 14 mm light-path panel photobioreactor under high irradiance was determined. Under continuous illumination of 2100 μmol photons m-2 s-1 with red LEDs (light emitting diodes) the effect of dilution rate on photobioreactor productivity was studied. The light intensity used in this work is similar to the maximal irradiance on a horizontal surface at latitudes lower than 37º. Chlorella sorokiniana, a fast-growing green microalga, was used as a reference strain in this study. The dilution rate was varied from 0.06 h-1 to 0.26 h-1. The maximal productivity was reached at a dilution rate of 0.24 h-1, with a value of 7.7 g of dry weight m-2 h-1 (m2 of illuminated photobioreactor surface) and a volumetric productivity of 0.5 g of dry weight L-1 h- 1. At this dilution rate the biomass concentration inside the reactor was 2.1 g L-1 and the photosynthetic efficiency was 1.0 g dry weight per mol photons. This biomass yield on light energy is high but still lower than the theoretical maximal yield of 1.8 g mol photons-1 which must be related to photosaturation and thermal dissipation of absorbed light energy