Integrable models for asymmetric Fermi superfluids: Emergence of a new exotic pairing phase

We introduce an exactly-solvable model to study the competition between the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) and breached-pair superfluid in strongly interacting ultracold asymmetric Fermi gases. One can thus investigate homogeneous and inhomogeneous states on an equal footing and establish the quantum phase diagram. For certain values of the filling and the interaction strength, the model exhibits a new stable exotic pairing phase which combines an inhomogeneous state with an interior gap to pair-excitations. It is proven that this phase is the exact ground state in the strong coupling limit, while numerical examples demonstrate that also at finite interaction strength it can have lower energy than the breached-pair or LOFF states.Comment: Revised version accepted for publicatio

Regularization of Diagrammatic Series with Zero Convergence Radius

The divergence of perturbative expansions for the vast majority of macroscopic systems, which follows from Dyson's collapse argument, prevents Feynman's diagrammatic technique from being directly used for controllable studies of strongly interacting systems. We show how the problem of divergence can be solved by replacing the original model with a convergent sequence of successive approximations which have a convergent perturbative series. As a prototypical model, we consider the zero-dimensional $\vert \psi \vert^4$ theory.Comment: 4 pages, 3 figure

Microalgae production cost in aquaculture hatcheries

Microalgae are a crucial part in many aquaculture feed applications processes, mainly in hatcheries. Many aquaculture hatcheries maintain a small scale microalgae production facility in-house for the production of live feed. Microalgae are usually grown in non-automated bubble-column systems at unknown production costs. Other reactor systems or scenarios utilizing artificial light or sunlight and at different scales could result in a more cost efficient production processes. To determine the cost-price and cost-distribution of microalgae production facilities in Dutch aquaculture industry and identify the most efficient cost reducing strategies a techno-economic analysis for small scale microalgae production facilities (25-1500 m2) was developed. Commercially available reactors commonly used in aquaculture were compared; tubular photobioreactors (TPBR) and bubble-columns (BC) in two placement possibilities; using artificial light in an indoor facility (AL) and utilizing sunlight in a greenhouse (GH) under Dutch climate conditions. Data from commercial microalgae facilities in the Netherlands are used to model reference scenarios describing the cost price of microalgae production with state of the art technology in aquaculture for a biomass production capacity of 125 kg year−1. The reference cost price for algae biomass (on the basis of dry matter) is calculated at €290,- kg−1 and € 329 kg−1 for tubular reactors under artificial light and a greenhouse, respectively and €587,- kg−1 and €573 kg−1 for bubble-columns under artificial light and a greenhouse, respectively. The addition of more artificial light will significantly reduce production costs (by 33%) in all small-scale systems modelled. Biomass yield on light (Yx,ph) showed the largest effect on cost price when not considering a different scale of the production process. Process parameters like temperature control should be aimed at optimizing Yx,ph rather than other forms of cost reduction. The scale of a microalgae production facility has a very large impact on the cost price. With state of the art technologies a cost price reduction of 92% could be achieved by changing the scale from 25m2 to 1500m2, resulting in a cost price of €43,- kg−1, producing 3992 kg year−1 for tubular reactors in a greenhouse. The presented techno-economic model gives valuable insights in the cost price distribution of microalgae production in aquaculture. This allows to focus research efforts towards the most promising cost reduction methods and to optimize existing production facilities in aquaculture companies to achieve economically sustainable microalgae production for live feed in hatcheries.publishedVersionPaid Open Acces

Optimization of Rhodomonas sp. under continuous cultivation for industrial applications in aquaculture

The microalgae species Rhodomonas sp. is commonly used in aquaculture for its high nutritional value due to the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content. Understanding the effect of cultivation parameters on biomass production rate and composition is presently limited, however essential in further commercialization of this strain. Under nutrient replete conditions, light intensity and temperature are the main factors determining biomass growth and composition. Therefore, the combined effect of light and temperature on the biomass production rate and biomass composition of Rhodomonas sp. was studied using a statistical Design of Experiment approach. Rhodomonas sp. was cultivated under continuous (turbidostat) conditions in lab-scale reactor systems (1.8 l) under different temperature (15–20–25–30 °C) and light conditions (60–195–330–465–600 μmol m−2 s−1). Stable biomass production was observed under all conditions except experiments performed at 30 °C, which led to cell death. Under optimized growth conditions, high growth rates (>1.0d−1) and high biomass production rates, up to 1.5 g l−1 d−1, were obtained in this study. The biomass production rate reported here is >10-fold higher than values reported in literature on Rhodomonas sp. The optimal temperature for maximal growth was found at T = 22–24 °C under all light conditions. The maximum biomass yield on light (Yx,ph – 0.87 g mol−1) was found at light levels between 110 and 220 μmol m−2 s−1. The fatty acid profile was only significantly influenced by temperature, with higher EPA and DHA contents at lower temperatures (15 °C). A total fatty acid (TFA) content of 8–10% of the total dry-weight was found for all tested conditions. The EPA content fluctuated between 9 and 16% of TFA and DHA content between 6 and 9% of TFA, only affected by temperature. A maximum EPA + DHA production rate of 114 mg l‐−1 d−1 was obtained at 20 °C and high light (600 μmol m−2 s−1) conditions.publishedVersionPaid Open Acces

Production of Rhodomonas sp. at pilot scale under sunlight conditions

Rhodomonas sp., is an important microalga for aquaculture feed applications and gained increased research interest over the past few years. While efforts to optimise cultivation of the strain have been studied in detail under laboratory conditions, Rhodomonas sp. has never been grown in photobioreactors at large scale under outdoor light conditions. To study the industrial potential of this strain, we cultivated Rhodomonas sp. in three identical tubular photobioreactors with 200 l working volume each, located in a greenhouse using sunlight conditions only. Growth experiments were performed from February with winter light conditions (−2 d−1) up to high light conditions of summer (>50 mol m−2 d−1) in July, representing all sunlight conditions in the Netherlands. All nutrients were supplied in surplus and temperature and pH were maintained at optimum values for growth of Rhodomonas sp., based on lab data. The total light per reactor was calculated using a ray-tracing analysis to allow calculations based on the light reaching each individual reactor. Rhodomonas sp. grew under all tested light conditions. Biomass yield on light decreased with increasing light conditions from 0.43 ± 0.21 g mol−1 to 0.18 ± 0.04 g mol−1 at 0–10 molph m−2 d−1 to 30–40 molph m−2 d−1. Biomass productivities increased with increasing light from 0.09 ± 0.04 g l−1 d−1 to 0.19 ± 0.06 g l−1 d−1, for 0–10 and 30–40 molph m−2 d−1. We obtained a 2–5 fold increase in biomass productivity compared to previous reports on Rhodomonas sp. cultivation using artificial light at large scale. Our results show that Rhodomonas sp. can be grown at pilot scale using sunlight conditions and further improvements can be reached in the future.</p

Verslag studiereis aquacultuur Spanje

Zeeuwse aquacultuurondernemers zijn in januari 2013 vier dagen naar de regio Cadiz en Huelva in Spanje afgereisd om kennis te maken met de aquacultuuractiviteiten en te leren van de ervaringen daar. Deze studiereis is georganiseerd in het kader van het inmiddels afgeronde RAAK Internationaal project 'Het zoute goud', waarvan HZ University of Applied Sciences penvoerder was. De studiereis naar Spanje vormde samen met een slotsymposium de afsluiting van dit project

Optimal Monte Carlo Updating

Based on Peskun's theorem it is shown that optimal transition matrices in Markov chain Monte Carlo should have zero diagonal elements except for the diagonal element corresponding to the largest weight. We will compare the statistical efficiency of this sampler to existing algorithms, such as heat-bath updating and the Metropolis algorithm. We provide numerical results for the Potts model as an application in classical physics. As an application in quantum physics we consider the spin 3/2 XY model and the Bose-Hubbard model which have been simulated by the directed loop algorithm in the stochastic series expansion framework.Comment: 6 pages, 5 figures, replaced with published versio

Production of Rhodomonas sp. at pilot scale under sunlight conditions

publishedVersionPaid Open Acces

Statistical Modeling of Lower Limb Kinetics During Deep Squat and Forward Lunge.

PURPOSE: Modern statistics and higher computational power have opened novel possibilities to complex data analysis. While gait has been the utmost described motion in quantitative human motion analysis, descriptions of more challenging movements like the squat or lunge are currently lacking in the literature. The hip and knee joints are exposed to high forces and cause high morbidity and costs. Pre-surgical kinetic data acquisition on a patient-specific anatomy is also scarce in the literature. Studying the normal inter-patient kinetic variability may lead to other comparable studies to initiate more personalized therapies within the orthopedics. METHODS: Trials are performed by 50 healthy young males who were not overweight and approximately of the same age and activity level. Spatial marker trajectories and ground reaction force registrations are imported into the Anybody Modeling System based on subject-specific geometry and the state-of-the-art TLEM 2.0 dataset. Hip and knee joint reaction forces were obtained by a simulation with an inverse dynamics approach. With these forces, a statistical model that accounts for inter-subject variability was created. For this, we applied a principal component analysis in order to enable variance decomposition. This way, noise can be rejected and we still contemplate all waveform data, instead of using deduced spatiotemporal parameters like peak flexion or stride length as done in many gait analyses. In addition, this current paper is, to the authors' knowledge, the first to investigate the generalization of a kinetic model data toward the population. RESULTS: Average knee reaction forces range up to 7.16 times body weight for the forwarded leg during lunge. Conversely, during squat, the load is evenly distributed. For both motions, a reliable and compact statistical model was created. In the lunge model, the first 12 modes accounts for 95.26% of inter-individual population variance. For the maximal-depth squat, this was 95.69% for the first 14 modes. Model accuracies will increase when including more principal components. CONCLUSION: Our model design was proved to be compact, accurate, and reliable. For models aimed at populations covering descriptive studies, the sample size must be at least 50

Finite-temperature effects on the superfluid Bose-Einstein condensation of confined ultracold atoms in three-dimensional optical lattices

We discuss the finite-temperature phase diagram in the three-dimensional Bose-Hubbard (BH) model in the strong correlation regime, relevant for Bose-Einstein condensates in optical lattices, by employing a quantum rotor approach. In systems with strong on site repulsive interactions, the rotor U(1) phase variable dual to the local boson density emerges as an important collective field. After establishing the connection between the rotor construction and the the on--site interaction in the BH model the robust effective action formalism is developed which allows us to study the superfluid phase transition in various temperature--interaction regimes