102 results on '"Gunnar Carlsson"'
Search Results
2. JD.com: Operations Research Algorithms Drive Intelligent Warehouse Robots to Work
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Hengle Qin, Jun Xiao, Dongdong Ge, Linwei Xin, Jianjun Gao, Simai He, Haodong Hu, and John Gunnar Carlsson
- Abstract
JD.com pioneered same-day delivery as a standard service in China’s business-to-consumer e-commerce sector in 2010. To balance the urgent need to meet growing demands while maintaining high-quality logistics services, the company built intelligent warehouses that use analytics to significantly improve warehouse efficiency. The brain of the intelligent warehouse system is the dispatching algorithm for storage rack-moving robots, which makes real-time dispatching decisions among robots, racks, and workstations after solving large-scale integer programs in seconds. The intelligent warehouse technology has helped the company decrease its fulfillment expense ratio to a world-leading level of 6.5%. The construction of intelligent warehouses has led to estimated annual savings of hundreds of millions of dollars. In 2020, JD.com delivered 90% of its first-party-owned retail orders on the same day or on the day after the order was placed. The agility of such intelligent warehouses has allowed JD.com to handle 10 times the normal volume of orders during peak sales seasons and has also helped the company respond quickly to COVID-19 and ensure the rapid recovery of production capabilities.
- Published
- 2022
3. Effect of stabilization method and freeze/thaw-aided precipitation on structural and functional properties of proteins recovered from brown seaweed (Saccharina latissima)
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Eva Albers, John Axelsson, Ingrid Undeland, Göran M. Nylund, Nils-Gunnar Carlsson, and Mehdi Abdollahi
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010304 chemical physics ,biology ,Precipitation (chemistry) ,Chemistry ,General Chemical Engineering ,04 agricultural and veterinary sciences ,General Chemistry ,Protein degradation ,Saccharina latissima ,biology.organism_classification ,040401 food science ,01 natural sciences ,0404 agricultural biotechnology ,Protein structure ,Isoelectric point ,Algae ,Yield (chemistry) ,0103 physical sciences ,Protein precipitation ,Food science ,Food Science - Abstract
Structural, functional and nutritional properties of protein recovered from brown seaweed, S. latissima with alkaline solubilization/isoelectric precipitation as a function of different post-harvest stabilization methods were studied. The latter included freezing at −20 °C/-80 °C, oven-drying, sun-drying, freeze-drying and ensilaging. Also, the efficacy of freeze/thaw-aided precipitation (F/T) in improving protein recovery of the process was evaluated. The freeze-dried, oven-dried, and −20 °C frozen seaweeds resulted in significantly higher protein yield than the −80°C-frozen, sun-dried and ensiled biomasses. F/T increased protein precipitation and doubled total protein yield. Sun-drying and −20°C-freezing caused extensive protein degradation as revealed by SDS-PAGE and HP-SEC, while oven-drying altered the seaweed protein structure with less α-helices. Functional properties of the seaweed proteins were remarkably affected by stabilization condition and F/T, but nutritional value of the proteins was only dependent on stabilization method. Thus, to efficiently recover seaweed proteins, its post-harvest stabilization condition must be carefully chosen based on the final application of the proteins.
- Published
- 2019
4. Topological Data Analysis with Applications
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Gunnar Carlsson and Mikael Vejdemo-Johansson
- Abstract
The continued and dramatic rise in the size of data sets has meant that new methods are required to model and analyze them. This timely account introduces topological data analysis (TDA), a method for modeling data by geometric objects, namely graphs and their higher-dimensional versions: simplicial complexes. The authors outline the necessary background material on topology and data philosophy for newcomers, while more complex concepts are highlighted for advanced learners. The book covers all the main TDA techniques, including persistent homology, cohomology, and Mapper. The final section focuses on the diverse applications of TDA, examining a number of case studies drawn from monitoring the progression of infectious diseases to the study of motion capture data. Mathematicians moving into data science, as well as data scientists or computer scientists seeking to understand this new area, will appreciate this self-contained resource which explains the underlying technology and how it can be used.
- Published
- 2021
5. Fermentation of pseudocereals quinoa, canihua, and amaranth to improve mineral accessibility through degradation of phytate
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Daysi Perez-Rea, Annette Almgren, Claudia E. Lazarte, Björn Bergenståhl, Nils-Gunnar Carlsson, Vanesa Castro-Alba, and Yvonne Granfeldt
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Phytic Acid ,mineral accessibility ,030309 nutrition & dietetics ,Flour ,Amaranth ,Chenopodium ,03 medical and health sciences ,chemistry.chemical_compound ,0404 agricultural biotechnology ,pseudocereals ,phytate ,Humans ,Mineral absorption ,Food science ,Chenopodium quinoa ,Research Articles ,Minerals ,0303 health sciences ,Amaranthus ,Nutrition and Dietetics ,biology ,Chemistry ,food and beverages ,04 agricultural and veterinary sciences ,biology.organism_classification ,040401 food science ,estimated bioavailability ,Lactic acid ,Gastrointestinal Tract ,Pseudocereal ,lactic acid fermentation ,Fermentation ,Phytase ,Edible Grain ,Agronomy and Crop Science ,Lactic acid fermentation ,Lactobacillus plantarum ,Research Article ,Food Science ,Biotechnology - Abstract
BACKGROUND Pseudocereals are nutrient‐rich grains with high mineral content but also phytate content. Phytate is a mineral absorption inhibitor. The study's aim was to evaluate phytate degradation during spontaneous fermentation and during Lactobacillus plantarum 299v® fermentation of quinoa, canihua, and amaranth grains and flours. It also aimed to evaluate the accessibility of iron, zinc, and calcium and to estimate their bioavailability before and after the fermentation of flours with starter culture. Lactic acid, pH, phytate, and mineral content were analyzed during fermentation. RESULTS Higher phytate degradation was found during the fermentation of flours (64–93%) than during that of grains (12–51%). Results suggest that phytate degradation was mainly due to endogenous phytase activity in different pseudocereals rather than the phytase produced by added microorganisms. The addition of Lactobacillus plantarum 299v® resulted in a higher level of lactic acid (76.8–82.4 g kg−1 DM) during fermentation, and a relatively quicker reduction in pH to 4 than in spontaneous fermentation. Mineral accessibility was increased (1.7–4.6‐fold) and phytate : mineral molar ratios were reduced (1.5–4.2‐fold) in agreement with phytate degradation (1.8–4.2‐fold) in fermented flours. The reduced molar ratios were still above the threshold value for the improved estimated mineral bioavailability of mainly iron. CONCLUSION Fermentation proved to be effective for degrading phytate in pseudocereal flours, but less so in grains. Fermentation with Lactobacillus plantarum 299v® improved mineral accessibility and estimated bioavailability in flours. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
- Published
- 2019
6. Distributions with Maximum Spread Subject to Wasserstein Distance Constraints
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Ye Wang and John Gunnar Carlsson
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021103 operations research ,Covariance matrix ,media_common.quotation_subject ,0211 other engineering and technologies ,Robust optimization ,010103 numerical & computational mathematics ,02 engineering and technology ,Ambiguity ,Management Science and Operations Research ,01 natural sciences ,Set (abstract data type) ,Distribution (mathematics) ,Subject (grammar) ,Applied mathematics ,Center of mass ,0101 mathematics ,Quantile ,media_common ,Mathematics - Abstract
Recent research on formulating and solving distributionally robust optimization problems has seen many different approaches for describing one’s ambiguity set, such as constraints on first and second moments or quantiles. In this paper, we use the Wasserstein distance to characterize the ambiguity set of distributions, which allows us to circumvent common overestimation that arises when other procedures are used, such as fixing the center of mass and the covariance matrix of the distribution. In particular, we derive closed-form expressions for distributions that are as “spread out” as possible, and apply our result to a problem in multi-vehicle coordination.
- Published
- 2019
7. Aquafeed ingredient production from herring (Clupea harengus) by-products using pH-shift processing: Effect from by-product combinations, protein solubilization-pH and centrifugation force
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James Hinchcliffe, Nils-Gunnar Carlsson, Kristina Sundell, Elisabeth Jönsson, and Ingrid Undeland
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chemistry.chemical_classification ,Methionine ,biology ,Potassium ,Lysine ,chemistry.chemical_element ,Clupea ,biology.organism_classification ,Amino acid ,chemistry.chemical_compound ,Ingredient ,Fish meal ,chemistry ,By-product ,Animal Science and Zoology ,Food science - Abstract
There is a strong need in animal production for sustainable protein sources used in feed. The aim of the present study was to evaluate the potential of the pH-shift process as a method to concentrate proteins from complex bone-rich herring (Clupea harengus) by-products. By-product parts (frame, head, guts), protein solubilization pH (pH 2.8 or 11.3) and separation g-force (800 or 8000 g) were varied. The findings revealed that protein recovery yields of up to 60% were obtained and that higher protein yield was obtained from the alkaline than the acid process. By-product part and g-force had no significant impact on protein yield. Protein levels reached in the concentrates were 75–80 % (dw basis). Protein concentrates contained a similar amino acid profile as have been reported for fishmeal, with ~40% essential amino acids and up to 7.8% and 2.8% of lysine and methionine. Residual levels of LC n-3 PUFA as well as calcium, magnesium, potassium and phosphorous were also found in the produced protein concentrates which could be an added value. Acid produced concentrates were particularly high in calcium potassium and phosphorous. Provided a careful evaluation, the pH-shift process could become a successful alternative to classic fish meal production for increasing the use of fish by-products for production of protein ingredients for feed.
- Published
- 2019
8. Wasserstein Distance and the Distributionally Robust TSP
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Kresimir Mihic, Mehdi Behroozi, and John Gunnar Carlsson
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Service (business) ,0209 industrial biotechnology ,Mathematical optimization ,021103 operations research ,020901 industrial engineering & automation ,Computer science ,0211 other engineering and technologies ,02 engineering and technology ,Management Science and Operations Research ,Travelling salesman problem ,Computer Science Applications - Abstract
One of the most common strategies used in large-scale logistics problems is districting, in which one divides a service region into smaller pieces. This is particularly useful when one does not know the true locations of demand, but has only limited information such as a probability distribution or a small set of sample data. In “Wasserstein Distance and the Distributionally Robust TSP,” Carlsson et al. show how to partition a region so as to balance the traveling salesman tours of a set of unknown points, using a distributionally robust method defined by a bound on the Wasserstein distance to a set of landmark points.
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- 2018
9. Continuous Approximation for Selection Routing Problems
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John Gunnar Carlsson
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2021
10. Provably Good Region Partitioning for On-Time Last-Mile Delivery
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Nooshin Salari, Sheng Liu, Han Yu, and John Gunnar Carlsson
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Structure (mathematical logic) ,History ,Queueing theory ,Mathematical optimization ,Service (systems architecture) ,Polymers and Plastics ,Computer science ,Discrete geometry ,Ranging ,Industrial and Manufacturing Engineering ,Order (exchange) ,Vehicle routing problem ,Business and International Management ,Routing decision - Abstract
On-time last-mile delivery is expanding rapidly as people expect faster delivery of goods ranging from grocery to medicines. Managing on-time delivery systems is challenging because of the underlying uncertainties and combinatorial nature of the routing decision. In practice, the efficiency of such systems also hinges on the driver's familiarity with the local neighborhood. This paper studies the optimal region partitioning policy to minimize the expected delivery time of customer orders in a stochastic and dynamic setting. We allow both the order locations and on-site service times to be random and generally distributed. This policy assigns every driver to a subregion, hence making sure drivers will only be dispatched to their own territories. We characterize the structure of the optimal partitioning policy and show its expected on-time performance converges to that of the flexible dispatching policy in heavy traffic. The optimal characterization features two insightful conditions that are critical to the on-time performance of last-mile delivery systems. We then develop partitioning algorithms with performance guarantees, leveraging ham sandwich cuts and 3-partitions from discrete geometry. This algorithmic development can be of independent interest for other logistics problems. We demonstrate the efficiency of the proposed region partitioning policy via numerical experiments using synthetic and real-world data sets.
- Published
- 2021
11. Carbamazepine Ozonation Byproducts: Toxicity in Zebrafish (
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Johannes, Pohl, Oksana, Golovko, Gunnar, Carlsson, Johan, Eriksson, Anders, Glynn, Stefan, Örn, and Jana, Weiss
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Carbamazepine ,Ozone ,Sewage ,Animals ,Prospective Studies ,Water Pollutants, Chemical ,Zebrafish ,Article - Abstract
Carbamazepine (CBZ) is an anticonvulsant medication with highly persistent properties in the aquatic environment, where it has the potential to affect nontarget biota. Because CBZ and many other pharmaceuticals are not readily removed in conventional sewage treatment plants (STP), additional STP effluent treatment technologies are being evaluated and implemented. Whole effluent ozonation is a prospective method to remove pharmaceuticals such as CBZ, yet knowledge on the toxicity of CBZ ozonation byproducts (OBPs) is lacking. This study presents, for the first time, in vivo individual and mixture toxicity of four putative OBPs, that is, carbamazepine 10,11-epoxide, 10,11-Dihydrocarbamazepine, 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM), and 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD) in developing zebrafish (Danio rerio) embryos. BQM and BQD were isolated from the ozonated solution as they were not commercially available. The study confirmed that the OBP mixture caused embryotoxic responses comparable to that of ozonated CBZ. Individual compound embryotoxicity assessment further revealed that BQM and BQD were the drivers of embryotoxicity. OBP chemical stability in ozonated CBZ water solution during 2 week dark storage at 22 °C was also assessed. The OBP concentrations remained over time, except for BQD which decreased by 94%. Meanwhile, ozonated CBZ persistently induced embryotoxicity over 2 week storage, potentially illustrating environmental concern.
- Published
- 2020
12. Coordinated Logistics with a Truck and a Drone
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John Gunnar Carlsson and Siyuan Song
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Truck ,050210 logistics & transportation ,Service (systems architecture) ,021103 operations research ,Operations research ,Computer science ,Strategy and Management ,05 social sciences ,0211 other engineering and technologies ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,02 engineering and technology ,Management Science and Operations Research ,Drone ,0502 economics and business ,Routing (electronic design automation) ,Simulation - Abstract
We determine the efficiency of a delivery system in which an unmanned aerial vehicle (UAV) provides service to customers while making return trips to a truck that is itself moving. In other words, a UAV picks up a package from the truck (which continues on its route), and after delivering the package, the UAV returns to the truck to pick up the next package. Although the hardware for such systems already exists, the extent to which such an approach can actually provide a significantly improved quality of service is not yet understood. By combining a theoretical analysis in the Euclidean plane with real-time numerical simulations on a road network, we demonstrate that the improvement in efficiency is proportional to the square root of the ratio of the speeds of the truck and the UAV. The online supplement is available at https://doi.org/10.1287/mnsc.2017.2824 . This paper was accepted by Vishal Gaur, operations management.
- Published
- 2018
13. Production of protein extracts from Swedish red, green, and brown seaweeds, Porphyra umbilicalis Kützing, Ulva lactuca Linnaeus, and Saccharina latissima (Linnaeus) J. V. Lamouroux using three different methods
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Hanna Harrysson, Gunilla B. Toth, Maria Hayes, Nils-Gunnar Carlsson, Ingrid Undeland, Friederike Eimer, Swedish Foundation for Strategic Research, and Swedish Research Council Formas
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0301 basic medicine ,Lactuca ,Plant Science ,Accelerated solvent extraction (ASE®) ,Aquatic Science ,Saccharina latissima ,01 natural sciences ,03 medical and health sciences ,food ,Algae ,pH shift ,Protein purification ,Protein precipitation ,Protein extraction ,Food science ,Ammonium sulfate precipitation ,030109 nutrition & dietetics ,biology ,Chemistry ,010401 analytical chemistry ,Seaweed ,biology.organism_classification ,food.food ,0104 chemical sciences ,Porphyra umbilicalis ,Polyphenol ,Amino acids ,Ulva lactuca - Abstract
peer-reviewed The demand for vegetable proteins increases globally and seaweeds are considered novel and promising protein sources. However, the tough polysaccharide-rich cell walls and the abundance of polyphenols reduce the extractability and digestibility of seaweed proteins. Therefore, food grade, scalable, and environmentally friendly protein extraction techniques are required. To date, little work has been carried out on developing such methods taking into consideration the structural differences between seaweed species. In this work, three different protein extraction methods were applied to three Swedish seaweeds (Porphyra umbilicalis, Ulva lactuca, and Saccharina latissima). These methods included (I) a traditional method using sonication in water and subsequent ammonium sulfate-induced protein precipitation, (II) the pH-shift protein extraction method using alkaline protein solubilization followed by isoelectric precipitation, and (III) the accelerated solvent extraction (ASE®) method where proteins are extracted after pre-removal of lipids and phlorotannins. The highest protein yields were achieved using the pH-shift method applied to P. umbilicalis (22.6 ± 7.3%) and S. latissima (25.1 ± 0.9%). The traditional method resulted in the greatest protein yield when applied to U. lactuca (19.6 ± 0.8%). However, the protein concentration in the produced extracts was highest for all three species using the pH-shift method (71.0 ± 3.7%, 51.2 ± 2.1%, and 40.7 ± 0.5% for P. umbilicalis, U. lactuca, and S. latissima, respectively). In addition, the pH-shift method was found to concentrate the fatty acids in U. lactuca and S. latissima by 2.2 and 1.6 times, respectively. The pH-shift method can therefore be considered a promising strategy for producing seaweed protein ingredients for use in food and feed.
- Published
- 2018
14. Enzyme pre-treatment of soybean meal: Effects on non-starch carbohydrates, protein, phytic acid, and saponin biotransformation and digestibility in mink ( Neovison vison )
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Hans Jákup Jacobsen, Katerina Kousoulaki, Øystein Ahlstrøm, Åge Oterhals, Nils-Gunnar Carlsson, and Ann-Sofie Sandberg
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0106 biological sciences ,Phytic acid ,biology ,Starch ,Soybean meal ,04 agricultural and veterinary sciences ,01 natural sciences ,chemistry.chemical_compound ,Hydrolysis ,chemistry ,Biochemistry ,Solid-state fermentation ,010608 biotechnology ,biology.animal ,Enzymatic hydrolysis ,040102 fisheries ,0401 agriculture, forestry, and fisheries ,Animal Science and Zoology ,Dry matter ,Food science ,Mink - Abstract
The study was conducted to examine if crude enzymes (E) produced from Aspergillus niger by solid state fermentation could bio-transform carbohydrates, proteins, inositol phosphate (InsP) and saponins in soybean meal (SBM) under low moisture conditions. Two experiments were performed to determine the effect of mixing, moisture content, treatment time and E levels during enzyme hydrolysis. 1) A single replicate 2 3 full factorial screening design was used to determine the effect of the independent continuous variables time (30 and 70 min), moisture (350 and 450 g kg −1 DM), and the category variable mixing (i.e. effect of static conditions vs. active mixing (X3, S/M)) during the enzyme hydrolysis. 2) A three factorial central composite design (CCD) was used to study the effects of moisture content (316–484 g kg −1 DM), time of hydrolysis (16.4–83.6 min), and E content (0.32-3.68 g kg −1 SBM dry matter (DM)). The first experiment demonstrated that hydrolysis of InsP 6 was significantly affected by time (P < 0.01), moisture content (P < 0.0001) and static vs. mixing (P < 0.01). The hydrolysis of Bb-DDMP was also significantly affected by static vs. mixing (P < 0.05). The second experiment demonstrated that the hydrolysis of InsP 6 was significantly affected by time (P < 0.001), moisture (P ˂ 0.001) and enzyme content (P ˂ 0.01). The InsP 6 content was reduced 84% after 70 min, at a moisture content of 450 g kg −1 DM with the addition of 3 g enzyme kg −1 SBM DM, the InsP 5 -InsP 3 were not accumulated at these parameter settings. The hydrolysis of the saponin group Bb was explained by the enzyme square regressor (P < 0.001) and the interaction between moisture and enzyme (P < 0.001) reaching a maximum by the addition of 2.5 g enzymes kg −1 SBM DM at 484 g kg −1 moisture content. No significant effects on soluble protein and dietary fiber were observed. Mink were fed three diets containing 50% of the protein from SBM, SBM treated without enzymes or treated with enzymes. There was a trend of improved ash apparent digestibility in mink by the enzyme treatment (P = 0.07), but not for phosphorous. The apparent digestibility of protein and amino acids (AA) in mink was improved by the heat treatment used to inactivate the enzymes (P < 0.001), however, not by the enzyme treatment itself.
- Published
- 2018
15. JMM 2018 Lecture Sampler
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Talithia Williams, Ronald E. Mickens, Jill Pipher, Gunnar Carlsson, Federico Ardila, Dana Randall, André Neves, Ruth Charney, and Erica N. Walker
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General Mathematics - Published
- 2018
16. Serum levels of Vitamin A and Atopic Rhinoconjunctivitis in Swedish adolescents
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Ann-Sofi e Sandberg, Malin Barman, Agnes E. Wold, Anna Sandin, and Nils-Gunnar Carlsson
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0301 basic medicine ,Vitamin ,Allergy ,business.industry ,Retinol ,Population based ,medicine.disease ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,chemistry ,Immunology ,medicine ,Birth cohort ,business ,Mucosal immunity - Abstract
Aim: Vitamin A plays a role in mucosal immunity and tolerance, but the association between vitamin A status and allergy is still unclear. The aim of the study was to analyze the levels of vitamin A in serum from adolescents with or without atopic rhinoconjunctivitis. Method: Thirteen-year-old children with atopic rhinoconjunctivitis (n = 53) and non-allergic, nonsensitized controls (n = 52) were randomly selected from a population based prospective birth cohort comprising 1228 children in Northern Sweden born in 1996-1997.
- Published
- 2017
17. Comparative survival and growth performance of European lobster larvae,Homarus gammarus, reared on dry feed and conspecifics
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James Hinchcliffe, Kristina Sundell, Nils-Gunnar Carlsson, Susanne P. Eriksson, and Adam Powell
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0106 biological sciences ,Larva ,biology ,business.industry ,010604 marine biology & hydrobiology ,fungi ,Cannibalism ,Aquatic animal ,04 agricultural and veterinary sciences ,Aquatic Science ,biology.organism_classification ,01 natural sciences ,Crustacean ,Hatchery ,Fishery ,Animal science ,Homarus gammarus ,Aquaculture ,Gammarus ,040102 fisheries ,0401 agriculture, forestry, and fisheries ,business - Abstract
A bottleneck of crustacean larval culture concerns nutrition and associated cannibalism in communal rearing systems, which impact on larval survival, development and growth. For early-stage European lobster, Homarus gammarus larvae, feeding ecology and body composition are largely unknown. We initiated four progressive feeding experiments (novel feed types, feeding regime and feed size and cannibalism effects) on growth and survival, to inform and update husbandry protocols. Performance of larvae offered a dry commercial feed was not significantly different compared with a conventional wet plankton feed of the same ration and size grade (both within 600-1,000m). Further experiments found that the same ration of dry feed offered six times daily improved development and growth, over the conventional regime of three times daily. Small-grade dry feed (particles: 250-360m) improved larval performance compared with a larger feed (360-650m). Larvae were also fed different proportions of dry feed and/or conspecifics in both communal and individual rearing systems (the latter preventing cannibalism via segregation). Individually reared larvae, fed only dead conspecifics, displayed the greatest survival (80%) to postlarvae. This underlines the impact of cannibalism on survival and nutrition in H. gammarus larviculture. A final experiment analysed H. gammarus zoea 1 composition, identifying deficiencies in ash and carbohydrate in lobster feeds. This suggests a need for a species-specific, formulated dry feed for H. gammarus larviculture. Our research represents the first investigation of H. gammarus larval composition and dietary requirements and highlights decreased growth potential associated with providing nutrition solely from generic commercial feed.
- Published
- 2017
18. Worst-case demand distributions in vehicle routing
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John Gunnar Carlsson and Mehdi Behroozi
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050210 logistics & transportation ,Focal point ,Continuous approximation ,Mathematical optimization ,021103 operations research ,Information Systems and Management ,General Computer Science ,05 social sciences ,0211 other engineering and technologies ,02 engineering and technology ,Management Science and Operations Research ,Industrial and Manufacturing Engineering ,Robustness (computer science) ,Time windows ,Modeling and Simulation ,0502 economics and business ,Vehicle routing problem ,In vehicle ,Economics - Abstract
A recent focal point in research on the vehicle routing problem (VRP) is the issue of robustness in which customer demand is uncertain. In this paper, we conduct a theoretical analysis of the demand distributions whose induced workloads are as undesirable as possible. We study two common variations of VRP in a continuous approximation setting: the first is the VRP with time windows, and the second is the capacitated VRP, in which regular returns to the vehicle’s point of origin are required.
- Published
- 2017
19. Household-Level Economies of Scale in Transportation
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John Gunnar Carlsson, Xiangfei Meng, Mehdi Behroozi, and Raghuveer Devulapalli
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050210 logistics & transportation ,021103 operations research ,05 social sciences ,0211 other engineering and technologies ,02 engineering and technology ,Management Science and Operations Research ,Travelling salesman problem ,Computer Science Applications ,Economies of scale ,Goods and services ,0502 economics and business ,Economics ,Marketing ,Industrial organization - Abstract
One of the fundamental concerns in the analysis of logistical systems is the trade-off between localized, independent provision of goods and services versus provision along a centralized infrastructure such as a backbone network. One phenomenon in which this trade-off has recently been made manifest is the transition of businesses from traditional brick-and-mortar stores to retail sales facilitated via e-commerce, such as grocery delivery services. Conventional wisdom would dictate that such services ought to be more efficient—say from the perspective of the overall carbon footprint—because of the economy of scale achieved by aggregating demand through a delivery van, as opposed to the many separate trips that customers would otherwise take using their own means of transport. In this paper, we quantify the changes in overall efficiency due to such services by looking at “household-level” economies of scale in transportation: a person might perform many errands in a day (such as going to the bank, grocery store, and post office), and that person has many choices of locations at which to perform these tasks (e.g., a typical metropolitan region has many banks, grocery stores, and post offices). Thus, the total driving distance (and therefore the overall carbon footprint) that that person traverses is the solution to a generalized travelling salesman problem (GTSP) in which they select both the best locations to visit and the sequence in which to visit them. We perform a probabilistic analysis of the GTSP under the assumption that all relevant locations are independently and identically distributed uniformly in a region and then determine the amount of adoption of such services that is necessary, under our model, in order for the overall carbon footprint of the region to decrease.
- Published
- 2016
20. Effect of fermentation and dry roasting on the nutritional quality and sensory attributes of quinoa
- Author
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Annette Almgren, Claudia E. Lazarte, Vanesa Castro-Alba, Daysi Perez-Rea, Björn Bergenståhl, Yvonne Granfeldt, Nils-Gunnar Carlsson, and Ann-Sofie Sandberg
- Subjects
0301 basic medicine ,dry roasting ,chemistry.chemical_element ,lcsh:TX341-641 ,Zinc ,sensory attributes ,minerals ,quinoa ,fermentation ,phytate degradation ,03 medical and health sciences ,0404 agricultural biotechnology ,Starter ,Food science ,Roasting ,Original Research ,030109 nutrition & dietetics ,Chemistry ,food and beverages ,04 agricultural and veterinary sciences ,040401 food science ,Bioavailability ,Pseudocereal ,Fermentation ,Phytase ,lcsh:Nutrition. Foods and food supply ,Lactic acid fermentation ,Food Science - Abstract
Background Quinoa is a pseudocereal with relatively high content of proteins and minerals that also contains mineral inhibitors such as phytate. The aim of the present study was to evaluate lactic acid fermentation and dry roasting on the nutritional quality and sensory attributes of quinoa. Various processes were evaluated, and quinoa grains were dry‐roasted, milled, and fermented, either with or without the addition of wheat phytase or activated quinoa phytase (added as back‐slop starter), for 10 hr. In other processes, raw quinoa flour was fermented for 10 hr or 4 hr and dry‐roasted. Hedonic sensory evaluation was then performed to evaluate the acceptability of the fermented flours prepared as porridges. Results The combined dry roasting and fermentation processes significantly (p, The combined dry roasting and fermentation processes degraded phytate in quinoa between 30% and 73% from initial content. The most effective process was fermentation of raw quinoa flour followed by dry roasting, which improved the estimated zinc and iron bioavailability. Phytate degradation was mainly attributed to the activation of endogenous phytase during fermentation. Dry roasting was effective in improving the sensory attributes of the fermented quinoa flour. Fermentation of quinoa flour for 4 hr followed by dry roasting was successful in improving both nutritional and sensory attributes of the final product.
- Published
- 2019
21. Embryotoxicity of ozonated diclofenac, carbamazepine, and oxazepam in zebrafish (Danio rerio)
- Author
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Johannes, Pohl, Lutz, Ahrens, Gunnar, Carlsson, Oksana, Golovko, Leif, Norrgren, Jana, Weiss, and Stefan, Örn
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Carbamazepine ,Diclofenac ,Ozone ,Sewage ,Oxazepam ,Animals ,Water Pollutants, Chemical ,Zebrafish - Abstract
Pharmaceutical residues are polluting the surface water environments worldwide. Sewage and wastewater treatment, therefore, needs to be improved in order to remove pharmaceutical residues from the effluent. One such treatment improvement is effluent ozonation. Even though ozonation has proven to be very efficient in reducing pharmaceutical parent compound concentrations in wastewater effluents, much remains unclear regarding potentially toxic ozonation by-product (OBP) formation. In this study, we sought to elucidate the aquatic toxicity of ozonated pharmaceuticals in zebrafish (Danio rerio) embryos in a static 144 h post fertilization (hpf) fish embryotoxicity (ZFET) assay. Three pharmaceuticals commonly detected in wastewater effluents, i.e. carbamazepine, diclofenac, and oxazepam, were selected for testing. Toxicity was assessed before and after 1 min ozonation (0.053 mg L
- Published
- 2018
22. Two Countermeasures Against Hardware Trojans Exploiting Non-Zero Aliasing Probability of BIST
- Author
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Mats Näslund, Gunnar Carlsson, John Fornehed, Elena Dubrova, and Ben Smeets
- Subjects
FOS: Computer and information sciences ,Computer Science - Cryptography and Security ,National security ,Test management ,Computer science ,Cryptography ,02 engineering and technology ,Computer security ,computer.software_genre ,Theoretical Computer Science ,Hardware Trojan ,0202 electrical engineering, electronic engineering, information engineering ,business.industry ,020202 computer hardware & architecture ,Hardware and Architecture ,Control and Systems Engineering ,Trojan ,Modeling and Simulation ,Embedded system ,Signal Processing ,Pattern recognition (psychology) ,Key (cryptography) ,020201 artificial intelligence & image processing ,Aliasing (computing) ,business ,Cryptography and Security (cs.CR) ,computer ,Computer hardware ,Information Systems - Abstract
The threat of hardware Trojans has been widely recognized by academia, industry, and government agencies. A Trojan can compromise security of a system in spite of cryptographic protection. The damage caused by a Trojan may not be limited to a business or reputation, but could have a severe impact on public safety, national economy, or national security. An extremely stealthy way of implementing hardware Trojans has been presented by Becker et al. at CHES'2012. Their work have shown that it is possible to inject a Trojan in a random number generator compliant with FIPS 140-2 and NIST SP800-90 standards by exploiting non-zero aliasing probability of Logic Built-In-Self-Test (LBIST). In this paper, we present two methods for modifying LBIST to prevent such an attack. The first method makes test patterns dependent on a configurable key which is programed into a chip after the manufacturing stage. The second method uses a remote test management system which can execute LBIST using a different set of test patterns at each test cycle., 16 pages, 5 figures
- Published
- 2016
23. Geometric partitioning and robust ad-hoc network design
- Author
-
John Gunnar Carlsson, Mehdi Behroozi, and Xiang Li
- Subjects
Convex hull ,0209 industrial biotechnology ,Mathematical optimization ,021103 operations research ,Wireless ad hoc network ,0211 other engineering and technologies ,Regular polygon ,General Decision Sciences ,Approximation algorithm ,02 engineering and technology ,Management Science and Operations Research ,Convex polygon ,Network planning and design ,020901 industrial engineering & automation ,Vehicle routing problem ,Theory of computation ,Mathematics - Abstract
We present fast approximation algorithms for the problem of dividing a given convex geographic region into smaller sub-regions so as to distribute the workloads of a set of vehicles. Our objective is to partition the region in such a fashion as to ensure that vehicles are capable of communicating with one another under limited communication radii. We consider variations of this problem in which sub-regions are constrained to have equal area or be convex, and as a side consequence, our approach yields a factor 1.99 approximation algorithm for the continuous k-centers problem on a convex polygon.
- Published
- 2015
24. A Bottleneck Matching Problem with Edge-Crossing Constraints
- Author
-
Saladi Rahul, John Gunnar Carlsson, Benjamin Armbruster, and Haritha Bellam
- Subjects
021103 operations research ,Matching (graph theory) ,Applied Mathematics ,0211 other engineering and technologies ,Approximation algorithm ,Astrophysics::Cosmology and Extragalactic Astrophysics ,02 engineering and technology ,Convex polygon ,Theoretical Computer Science ,Combinatorics ,Computational Mathematics ,Computational Theory and Mathematics ,Line (geometry) ,0202 electrical engineering, electronic engineering, information engineering ,Bipartite graph ,Astrophysics::Solar and Stellar Astrophysics ,020201 artificial intelligence & image processing ,Geometry and Topology ,Assignment problem ,Time complexity ,Astrophysics::Galaxy Astrophysics ,Linear separability ,Mathematics - Abstract
Motivated by a crane assignment problem, we consider a Euclidean bipartite matching problem with edge-crossing constraints. Specifically, given [Formula: see text] red points and [Formula: see text] blue points in the plane, we want to construct a perfect matching between red and blue points that minimizes the length of the longest edge, while imposing a constraint that no two edges may cross each other. We show that the problem cannot be approximately solved within a factor less than 1:277 in polynomial time unless [Formula: see text]. We give simple dynamic programming algorithms that solve our problem in two special cases, namely (1) the case where the red and blue points form the vertices of a convex polygon and (2) the case where the red points are collinear and the blue points lie to one side of the line through the red points.
- Published
- 2015
25. Shadow Prices in Territory Division
- Author
-
Erik Carlsson, John Gunnar Carlsson, and Raghuveer Devulapalli
- Subjects
Discrete mathematics ,050210 logistics & transportation ,Mathematical optimization ,021103 operations research ,Partial differential equation ,Optimization problem ,Computer Networks and Communications ,05 social sciences ,0211 other engineering and technologies ,Boundary (topology) ,Probability density function ,02 engineering and technology ,Computational geometry ,Dynamic problem ,Artificial Intelligence ,0502 economics and business ,Convex optimization ,Voronoi diagram ,Software ,Mathematics - Abstract
We consider a geographic optimization problem in which we are given a region R, a probability density function f(⋅) defined on R, and a collection of n utility density functions u i (⋅) defined on R. Our objective is to divide R into n sub-regions R i so as to “balance” the overall utilities on the regions, which are given by the integrals $\iint _{R_{i}}f(x)u_{i}(x)\, dA$ . Using a simple complementary slackness argument, we show that (depending on what we mean precisely by “balancing” the utility functions) the boundary curves between optimal sub-regions are level curves of either the difference function u i (x) − u j (x) or the ratio u i (x)/u j (x). This allows us to solve the problem of optimally partitioning the region efficiently by reducing it to a low-dimensional convex optimization problem. This result generalizes, and gives very short and constructive proofs of, several existing results in the literature on equitable partitioning for particular forms of f(⋅) and u i (⋅). We next give two economic applications of our results in which we show how to compute a market-clearing price vector in an aggregate demand system or a variation of the classical Fisher exchange market. Finally, we consider a dynamic problem in which the density function f(⋅) varies over time (simulating population migration or transport of a resource, for example) and derive a set of partial differential equations that describe the evolution of the optimal sub-regions over time. Numerical simulations for both static and dynamic problems confirm that such partitioning problems become tractable when using our methods.
- Published
- 2015
26. Continuous Facility Location with Backbone Network Costs
- Author
-
Fan Jia and John Gunnar Carlsson
- Subjects
Mathematical optimization ,Engineering ,Backbone network ,business.industry ,Heuristic ,Approximation algorithm ,Transportation ,Convex polygon ,Facility location problem ,Set (abstract data type) ,Asymptotically optimal algorithm ,Physics::Accelerator Physics ,business ,Fixed cost ,Civil and Structural Engineering - Abstract
We consider a continuous facility location problem in which our objective is to minimize the weighted sum of three costs: (1) fixed costs from installing the facilities, (2) backbone network costs incurred from connecting the facilities to each other, and (3) transportation costs incurred from providing services from the facilities to the service region. We first analyze the limiting behavior of this model and derive the two asymptotically optimal configurations of facilities: one of these configurations is the well studied honeycomb heuristic, and the other is an Archimedean spiral. We then give a fast constant-factor approximation algorithm for finding the placement of a set of facilities in any convex polygon that minimizes the sum of the three aforementioned costs.
- Published
- 2015
27. Phytate, zinc, iron and calcium content of common Bolivian food, and implications for mineral bioavailability
- Author
-
Claudia E. Lazarte, Ann-Sofie Sandberg, Nils-Gunnar Carlsson, Yvonne Granfeldt, and Annette Almgren
- Subjects
Mineral ,Chemistry ,Food frequency questionnaire ,chemistry.chemical_element ,Food composition data ,Zinc ,Calcium ,law.invention ,Bioavailability ,Mineral bioavailability ,law ,Food science ,Atomic absorption spectroscopy ,Food Science - Abstract
The content of zinc, iron, calcium and phytate in the 16 most consumed foods from 5 villages in a tropical rural area of Bolivia was analyzed. The fooditems were selected according to a completed food frequency questionnaire. Minerals were analyzed by atomic absorption and phytates by HPIC chromatography. The molar ratios of phytate:mineral are presented as indication of the mineral bioavailability. Within the analyzed food, quinoa is a potential source of minerals: zinc 3.65, iron 5.40 and calcium 176 mg/100 g; however, it also has the highest content of phytate 2060 mg/100 g. Cereals and legumes showed high concentration of phytates (from 142 to 2070 mg/100 g), roots and tubers have lower concentrations (from 77 to 427 mg/100 g). In general, both phytate contents and molar ratios Phy:Zn (phytate:zinc), Phy:Fe (phytate:iron) and Phy:Ca (phytate:calcium) in most of the analyzed foods were at levels likely to inhibit the absorption of these minerals. Significant positive associations (p < 0.01) were found between the level of phytate and minerals in food, for zinc (r = 0.714), iron (r = 0.650) and calcium (r = 0.415). The results compared to data from USA or from Bolivia showed some discrepancies, confirming the need for more reliable data for dietary evaluations and interventions.
- Published
- 2015
28. An Approximation Algorithm for the Continuous k-Medians Problem in a Convex Polygon
- Author
-
Fan Jia, Ying Li, and John Gunnar Carlsson
- Subjects
Discrete mathematics ,Combinatorics ,Polygon covering ,Minimum bounding box ,TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,General Engineering ,Convex set ,Regular polygon ,Approximation algorithm ,Minimum bounding box algorithms ,Krein–Milman theorem ,Convex polygon ,Mathematics - Abstract
We give a fast and simple factor 2.74 approximation algorithm for the problem of choosing the k medians of the continuum of demand points defined by a convex polygon C. Our algorithm first surrounds the input region with a bounding box, then subdivides the bounding box into subregions with equal area. Simulation results on the convex hulls of the 50 states in the United States show that the practical performance of our algorithm is within 10% of the optimal solution in the vast majority of cases.
- Published
- 2014
29. Euclidean Hub-and-Spoke Networks
- Author
-
Fan Jia and John Gunnar Carlsson
- Subjects
Backbone network ,Mathematical optimization ,Spanning tree ,business.industry ,Management Science and Operations Research ,Flow network ,Network topology ,Travelling salesman problem ,Computer Science Applications ,Network planning and design ,Spatial network ,Vehicle routing problem ,business ,Mathematics ,Computer network - Abstract
The hub-and-spoke distribution paradigm has been a fundamental principle in geographic network design for more than 40 years. One of the primary advantages that such networks possess is their ability to exploit economies of scale in transportation by aggregating network flows through common sources. In this paper, we consider the problem of designing an optimal hub-and-spoke network in continuous Euclidean space: the “spokes” of the network are distributed uniformly over a service region, and our objective is to determine the optimal number of hub nodes and their locations. We consider seven different backbone network topologies for connecting the hub nodes, namely, the Steiner and minimum spanning trees, a travelling salesman tour, a star network, a capacitated vehicle routing tour, a complete bipartite graph, and a complete graph. We also perform an additional analysis on a multilevel network in which network flows move through multiple levels of transshipment before reaching the service region. We describe the asymptotically optimal (or near-optimal) configurations that minimize the total network costs as the demand in the region becomes large and give an approximation algorithm that solves our problem on a convex planar region for any values of the relevant input parameters.
- Published
- 2013
30. Dividing a Territory Among Several Facilities
- Author
-
Raghuveer Devulapalli and John Gunnar Carlsson
- Subjects
Set (abstract data type) ,Mathematical optimization ,Monomial ,General Engineering ,Workload ,Probability density function ,Function (mathematics) ,Voronoi diagram ,Partition (database) ,Weighted Voronoi diagram ,Mathematics - Abstract
We consider the problem of dividing a geographic region into subregions so as to minimize the maximum workload of a collection of facilities over that region. We assume that the cost of servicing a demand point is a monomial function of the distance to its assigned facility and that demand points follow a continuous probability density. We show that, when our objective is to minimize the maximum workload of all facilities, the optimal partition consists of a collection of circular arcs that are induced by a multiplicatively weighted Voronoi diagram. When we require that all subregions have equal area, the optimal partition consists of a collection of hyperbolic or quartic curves. We show that, for both problems, the dual variables correspond to “prices” for a facility to serve a demand point, and our objective is to determine a set of prices such that the entire region is “purchased” by the facilities, i.e., that the market clears. This allows us to solve the partitioning problem quickly without discretizing the service region.
- Published
- 2013
31. A linear relaxation algorithm for solving the sum-of-linear-ratios problem with lower dimension
- Author
-
John Gunnar Carlsson and Jianming Shi
- Subjects
Mathematical optimization ,Work (thermodynamics) ,Branch and bound ,Applied Mathematics ,Management Science and Operations Research ,Space (mathematics) ,Industrial and Manufacturing Engineering ,Linear programming relaxation ,symbols.namesake ,Dimension (vector space) ,Lagrangian relaxation ,symbols ,Applied mathematics ,Relaxation (approximation) ,Global optimization ,Software ,Mathematics - Abstract
In this paper, we present an algorithm for solving the sum-of-linear-ratios problem based on a linear relaxation of the objective function. Though there already exist linear relaxation algorithms for solving this problem, they all work on a space whose dimension increases with the number of ratios. When the number of ratios becomes large, these algorithms are unable to solve the problem efficiently. Our numerical experiments indicate that the proposed algorithm in this paper is superior to these existing algorithms when the number of ratios is large.
- Published
- 2013
32. Robust Partitioning for Stochastic Multivehicle Routing
- Author
-
John Gunnar Carlsson and Erick Delage
- Subjects
Service (systems architecture) ,Mathematical optimization ,Operations research ,Heuristic ,business.industry ,Computer science ,Distribution (economics) ,Workload ,Management Science and Operations Research ,Routing (electronic design automation) ,business ,Computer Science Applications - Abstract
The problem of coordinating a fleet of vehicles so that all demand points on a territory are serviced and the workload is most evenly distributed among the vehicles is a hard one. For this reason, it is often an effective strategy to first divide the service region and impose that each vehicle is only responsible for its own subregion. This heuristic also has the practical advantage that over time, drivers become more effective at serving their territory and customers. In this paper, we assume that client locations are unknown at the time of partitioning the territory and that each of them will be drawn identically and independently according to a distribution that is actually also unknown. In practice, it might be impossible to identify precisely the distribution if, for instance, information about the demand is limited to historical data. Our approach suggests partitioning the region with respect to the worst-case distribution that satisfies first- and second-order moments information. As a side product, our analysis constructs for each subregion a closed-form expression for the worst-case density function, thus providing useful insights about what affects the completion time most heavily. The successful implementation of our approach relies on two branch-and-bound algorithms: whereas the first finds a globally optimal partition of a convex polygon into two convex subregions, the second finds a local optimum for the harder n-partitioning problem. Finally, simulations of a parcel delivery problem will demonstrate that our data-driven approach makes better use of historical data as it becomes available.
- Published
- 2013
33. Dividing a Territory Among Several Vehicles
- Author
-
John Gunnar Carlsson
- Subjects
Independent and identically distributed random variables ,Mathematical optimization ,Spanning tree ,Computer science ,Vehicle routing problem ,Metric (mathematics) ,Simply connected space ,General Engineering ,Probability density function ,Load balancing (computing) ,Lp space - Abstract
We consider an uncapacitated stochastic vehicle routing problem in which vehicle depot locations are fixed, and client locations in a service region are unknown but are assumed to be independent and identically distributed samples from a given probability density function. We present an algorithm for partitioning the service region into subregions so as to balance the workloads of all vehicles when the service region is simply connected and point-to-point distances follow some “natural” metric, such as any Lp norm. This algorithm can also be applied to load balancing of other combinatorial structures, such as minimum spanning trees and minimum matchings.
- Published
- 2012
34. Herring and chicken/pork meals lead to differences in plasma levels of TCA intermediates and arginine metabolites in overweight and obese men and women
- Author
-
Ingrid Undeland, Otto Savolainen, Andrew Vincent, Nils-Gunnar Carlsson, Alastair B. Ross, Mads Vendelbo Lind, Annette Almgren, Partho Sen, Ann-Sofie Sandberg, and Helen M. Lindqvist
- Subjects
0301 basic medicine ,Adult ,Male ,medicine.medical_specialty ,Arginine ,Biology ,Nitric Oxide ,03 medical and health sciences ,chemistry.chemical_compound ,Herring ,Blood serum ,Internal medicine ,Fish Products ,medicine ,Metabolome ,Animals ,Humans ,Obesity ,Amino Acids ,Aged ,chemistry.chemical_classification ,Tricarboxylic Acids ,Ornithine ,Middle Aged ,Overweight ,Crossover study ,Diet ,Glutamine ,Red Meat ,030104 developmental biology ,Endocrinology ,chemistry ,Female ,Chickens ,Food Science ,Biotechnology ,Polyunsaturated fatty acid - Abstract
SCOPE: What effect does replacing chicken or pork with herring as the main dietary source of protein have on the human plasma metabolome? METHOD AND RESULTS: A randomised crossover trial with 15 healthy obese men and women (age 24-70 years). Subjects were randomly assigned to four weeks of herring diet or a reference diet of chicken and lean pork, five meals per week, followed by a washout and the other intervention arm. Fasting blood serum metabolites were analysed at 0, 2 and 4 weeks for eleven subjects with available samples, using GC-MS based metabolomics. The herring diet decreased plasma citrate, fumarate, isocitrate, glycolate, oxalate, agmatine and methyhistidine and increased asparagine, ornithine, glutamine and the hexosamine glucosamine. Modelling found that the tricarboxylic acid cycle, glyoxylate, and arginine metabolism were affected by the intervention. The effect on arginine metabolism was supported by an increase in blood nitric oxide in males on the herring diet. CONCLUSION: The results suggest that eating herring instead of chicken and lean pork leads to important metabolic effects, particularly on energy and amino acid metabolism. Our findings support the hypothesis that there are metabolic effects of herring intake unrelated to the long chain n-3 polyunsaturated fatty acid content.
- Published
- 2016
35. Dephytinisation of Sangak and Barbari bread made from different extraction rate flours increases iron and zinc bioaccessibility in Caco-2 cells
- Author
-
Soodeh Shockravi, Ann-Sofie Sandberg, Annette Almgren, and Nils-Gunnar Carlsson
- Subjects
Phytic acid ,biology ,digestive, oral, and skin physiology ,Extraction (chemistry) ,Aspergillus niger ,food and beverages ,chemistry.chemical_element ,Zinc ,biology.organism_classification ,In vitro digestion ,Industrial and Manufacturing Engineering ,Bioavailability ,chemistry.chemical_compound ,Biochemistry ,chemistry ,Caco-2 ,Phytase ,Food science ,Food Science - Abstract
Bread is a staple food in many countries and an important source of iron and zinc. The bioavailability of these minerals is generally low because of the content of phytic acid. Traditional Iranian breads were prepared with flours of different extraction rates, Sangak at 93% and Barbari at 82%. Breads were dephytinised by addition of Aspergillus niger phytase during in vitro digestion. The effect upon iron and zinc bioaccessibility in the Caco-2 cell model was investigated. The cellular uptake of iron and zinc was lower from Sangak, compared to Barbari, despite higher mineral content in Sangak. Dephytinisation of both breads increased iron uptake in the Caco-2 cells (0.65 vs. 1.64 in Sangak and 0.77 vs. 1.97 ng mg-1 protein in Barbari). Zinc uptake increased from 0.98 to 2.8 in Sangak and from 1.4 to 2.9 ng mg-1 protein in Barbari. Thus, dephytinisation substantially improves iron and zinc bioaccessibility.
- Published
- 2012
36. The potential of bifidobacteria as a source of natural folate
- Author
-
Paola Mattarelli, Bruno Biavati, Maria Rosaria D'Aimmo, Nils-Gunnar Carlsson, and Thomas Andlid
- Subjects
Strain (chemistry) ,Auxotrophy ,food and beverages ,General Medicine ,Biology ,biology.organism_classification ,Applied Microbiology and Biotechnology ,law.invention ,Bifidobacterium animalis ,Probiotic ,Biochemistry ,law ,Composition (visual arts) ,Dry matter ,Fermentation ,Autotroph ,Biotechnology - Abstract
Aims: To screen 19 strains of bifidobacteria for main folate forms composition in synthetic folate-free and complex folate-containing media. Methods and Results: HPLC was used to analyse deconjugated folates extracted from bacterial biomass. Most strains had a total folate content above 4000 mu g per 100 g dry matter (DM). The highest value of 9295 mu g per 100 g DM was found in Bifidobacterium catenulatum ATCC 27539 and the lowest in Bifidobacterium animalis ssp. animalis ATCC 25527 containing 220 mu g per 100 g DM. Ten strains grew in a synthetic folate-free medium (FFM), showing folate autotrophy and suggesting folate auxotrophy of the remaining nine. In the autotrophic strains, a consistently higher folate level was found in FFM as compared to a more complex folate-containing medium, suggesting reduced requirements for folates in the presence of growth factors otherwise requiring folates for synthesis. The contents of total folate, 5-CH3-H(4)folate and H(4)folate were strain dependent. 5-CH3-H(4)folate dominated in most strains. Conclusions: Our results show that bifidobacteria folate content and composition is dynamic, is strain specific and depends on the medium. Suitable selection of the growth conditions can result in high levels of folate per cell unit biomass. Significance and Impact of the Study: This suggests that certain bifidobacteria may contribute to the folate intake, either directly in foods, such as fermented dairy products, or in the intestine as folate-trophic probiotics or part of the natural microbiota.
- Published
- 2012
37. Degradation of phytate by Pichia kudriavzevii TY13 and Hanseniaspora guilliermondii TY14 in Tanzanian togwa
- Author
-
Andreas M. Hellström, Annette Almgren, Thomas Andlid, Ulf Svanberg, and Nils-Gunnar Carlsson
- Subjects
chemistry.chemical_classification ,6-Phytase ,Phytic Acid ,Strain (chemistry) ,biology ,Saccharomyces cerevisiae ,General Medicine ,biology.organism_classification ,Tanzania ,Zea mays ,Microbiology ,Pichia ,Yeast ,Hanseniaspora ,Enzyme ,chemistry ,Biochemistry ,Fermentation ,Hanseniaspora guilliermondii ,Phytase ,Edible Grain ,Lactobacillus plantarum ,Food Science - Abstract
The fermented cereal-based gruel togwa is used as weaning food for children in Tanzania. Togwa is rich in minerals but these are often not available for uptake in the human intestine due to natural inhibitors, such as phytate (IP(6)). The yeasts Pichia kudriavzevii TY13, Hanseniaspora guilliermondii TY14 and TY20, isolated from Tanzanian togwa, and selected for high phytase activity in complex yeast medium YPD, were now studied regarding their ability to degrade IP(6) in maize-based model togwa. A modified constitutively high-phytase producing Saccharomyces cerevisiae BY80 and commercial Aspergillus ficuum phytase were included for comparison. In addition, a strain of Lactobacillus plantarum was included in the model-togwa set-up. All yeasts in the study grew and reached final cell density 1.5-2 log units higher than the start value. S. cerevisiae BY80 degraded 85% of the IP(6) in 48 h; the same degradation level as with A. ficuum phytase (89%). Of the togwa-isolated yeasts, P. kudriavzevii TY13 and H. guilliermondii TY14 showed strong phytate degradation in the model-togwa; 95% or more of the initial IP(6) was degraded after 48 h. This corresponds to a remaining level of 0.4 and 0.3μmol IP(6)/g dw. Co-inoculation with L. plantarum did not increase IP(6) degradation. Moreover, fermentation with P. kudriavzevii TY13 yielded a successive increase in inorganic phosphate (P(i)), from 0.7 to 5.4 mM, suggesting a phytase production in TY13 which is fairly insensitive to P(i) repression. The study shows that phytate in a model togwa is available for yeast phytase enzymes, and addresses the importance of strain selection for effectively degrading the phytate. Certain yeasts originating from togwa seem to have developed a natural high phytase production, and P. kudriavzevii TY13 and H. guilliermondii TY14 seem particularly well adapted to phytate degradation in togwa, and is our choice for further studies and strain improvement.
- Published
- 2012
38. Comments on: Continuous approximation models in freight distribution management
- Author
-
John Gunnar Carlsson
- Subjects
Statistics and Probability ,Mathematical optimization ,021103 operations research ,Information Systems and Management ,Geospatial analysis ,Optimization problem ,Numerical analysis ,05 social sciences ,0211 other engineering and technologies ,Probabilistic logic ,Regular polygon ,02 engineering and technology ,Management Science and Operations Research ,computer.software_genre ,Systems analysis ,Simple (abstract algebra) ,Modeling and Simulation ,0502 economics and business ,Discrete Mathematics and Combinatorics ,Algebraic expression ,computer ,050203 business & management ,Mathematics - Abstract
Any time a group of authors of this caliber gets together, the result is sure to be a great read, and this article is no exception. This paper is a survey of the continuous approximation paradigm for logistics systems analysis, which is a reductionist philosophy that seeks to isolate the factors that influence a geospatial optimization problem most significantly. The defining feature of continuous approximation models is that “detailed data are replaced by concise summaries, and numerical methods are replaced by analytic models” (Daganzo 2005); this means that rather than finding an algorithm to solve a particular problem instance efficiently, one seeks a simple, algebraic expression that approximates the true cost of that problem under suitable probabilistic or geometric conditions (e.g. a limiting condition under uniformly distributed demand in a convex planar region).
- Published
- 2017
39. Finding equitable convex partitions of points in a polygon efficiently
- Author
-
Benjamin Armbruster, John Gunnar Carlsson, and Yinyu Ye
- Subjects
Combinatorics ,Convex hull ,Mathematics (miscellaneous) ,Polygon covering ,Star-shaped polygon ,Convex polytope ,Convex set ,Convex combination ,Krein–Milman theorem ,Convex polygon ,Mathematics - Abstract
Previous work has developed algorithms for finding an equitable convex partition that partitions the plane into n convex pieces each containing an equal number of red and blue points. Motivated by a vehicle routing heuristic, we look at a related problem where each piece must contain one point and an equal fraction of the area of some convex polygon. We first show how algorithms for solving the older problem lead to approximate solutions for this new equitable convex partition problem. Then we demonstrate a new algorithm that finds an exact solution to our problem in O ( N n log N ) time or operations, where n is the number of points, m the number of vertices or edges of the polygon, and N := n + m the sum.
- Published
- 2010
40. Topological Modeling of Complex Data
- Author
-
Gunnar Carlsson
- Subjects
Complex data type ,Computer science ,General Mathematics ,Topology - Published
- 2018
41. CYTOLOGY OF THE BLACK FLY PROSIMULIUM FROHNEI SOMMERMAN
- Author
-
Gunnar Carlsson
- Subjects
biology ,Cytology ,Genetics ,Zoology ,General Medicine ,biology.organism_classification ,Black fly - Published
- 2009
42. The Theory of Multidimensional Persistence
- Author
-
Gunnar Carlsson and Afra Zomorodian
- Subjects
Computational Theory and Mathematics ,Discrete Mathematics and Combinatorics ,Geometry and Topology ,Theoretical Computer Science - Published
- 2009
43. myo-Inositol Phosphate Isomers Generated by the Action of a Phytase from a Malaysian Waste-water Bacterium
- Author
-
Ursula Konietzny, Nils-Gunnar Carlsson, Abd-Elaziem Farouk, and Ralf Greiner
- Subjects
Phytic Acid ,Stereochemistry ,Ion chromatography ,Molecular Conformation ,Bioengineering ,Biochemistry ,Analytical Chemistry ,Dephosphorylation ,chemistry.chemical_compound ,Hydrolysis ,Isomerism ,Bioorganic chemistry ,Inositol ,Phosphorylation ,Inositol phosphate ,Chromatography, High Pressure Liquid ,chemistry.chemical_classification ,6-Phytase ,Chromatography ,Bacteria ,Sewage ,Secale ,Organic Chemistry ,Phosphate ,Kinetics ,chemistry ,Phytase ,Water Microbiology - Abstract
Using a combination of High-Performance Ion Chromatography analysis and kinetic studies, the pathway of myo-inositol hexakisphosphate dephosphorylation by a phytase from a Malaysian waste-water bacterium was established. The data demonstrate that the phytase preferably dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-I(1,2,3,4,5)P(5), D-I(2,3,4,5)P(4), D-I(2,3,4)P(3), D-I(2,3)P(2) to finally I(2)P. It was estimated that more than 90% of phytate hydrolysis occurs via D-I(1,2,3,4,5)P(5). Thus, the phytase from the Malaysian waste-water bacterium has to be considered a 6-phytase (E.C. 3.1.3.26). A second pathway of minor importance could be proposed which is in accordance with the results obtained from analysis of the dephosphorylation products formed by the action of the phytase under investigation on myo-inositol hexakisphosphate. It proceeds via D/L-I(1,2,4,5,6)P(5), D/L-I(1,2,4,5)P(4), D/L-I(1,2,4)P(3), D/L-I(2,4)P(2) to finally I(2)P.
- Published
- 2007
44. A Scan Partitioning Algorithm for Reducing Capture Power of Delay-Fault LBIST
- Author
-
Nan Li, Elena Dubrova, and Gunnar Carlsson
- Published
- 2015
45. Data Visualization Using Weighted Voronoi Diagrams
- Author
-
Neil Peterson, Raghuveer Devulapalli, and John Gunnar Carlsson
- Subjects
Data visualization ,business.industry ,Computer science ,Computer graphics (images) ,Centroidal Voronoi tessellation ,business ,Voronoi diagram - Abstract
A Voronoi diagram is a standard spatial tessellation that partitions a domain into sub-regions based on proximity to a fixed set of landmark points. In order to maintain control over the size and shape of these sub-regions, a weighting scheme is often used, in which each landmark has a scalar value associated with it. This suggests a natural “inverse” problem: given a fixed set of landmark points in a given planar region and a set of “desired” areas, is it possible to calculate a set of weights so that each sub-region has a particular area? In this chapter, the authors give a fast scheme for determining these weights based on theory from convex optimization, which is then applied to a variety of problems in data visualization.
- Published
- 2015
46. myo-Inositol phosphate isomers generated by the action of a phytate-degrading enzyme from Klebsiella terrigena on phytate
- Author
-
Nils-Gunnar Carlsson and Ralf Greiner
- Subjects
Phytic Acid ,Inositol Phosphates ,Immunology ,Applied Microbiology and Biotechnology ,Microbiology ,Dephosphorylation ,chemistry.chemical_compound ,Isomerism ,Klebsiella terrigena ,Klebsiella ,Genetics ,Inositol phosphate ,Molecular Biology ,Chromatography, High Pressure Liquid ,Histidine ,chemistry.chemical_classification ,6-Phytase ,biology ,Substrate (chemistry) ,General Medicine ,Phosphate ,biology.organism_classification ,Enzyme ,chemistry ,Biochemistry ,Phytase ,Aspergillus niger ,Bacillus subtilis - Abstract
For the first time a dual pathway for dephosphorylation of myo-inositol hexakisphosphate by a histidine acid phytase was established. The phytate-degrading enzyme of Klebsiella terrigena degrades myo-inositol hexakisphosphate by stepwise dephosphorylation, preferably via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, D-Ins(1,2)P2 and alternatively via D-Ins(1,2,4,5,6)P5, Ins(2,4,5,6)P4, D-Ins(2,4,5)P3, D-Ins(2,4)P2 to finally Ins(2)P. It was estimated that more than 98% of phytate hydrolysis occurs via D-Ins(1,2,4,5,6)P5. Therefore, the phytate-degrading enzyme from K. terrigena has to be considered a 3-phytase (EC 3.1.3.8). A second dual pathway of minor importance could be proposed that is in accordance with the results obtained by analysis of the dephosphorylation products formed by the action of the phytate-degrading enzyme of K. terrigena on myo-inositol hexakisphosphate. It proceeds preferably via D-Ins(1,2,3,5,6)P5, D-Ins(1,2,3,6)P4, Ins(1,2,3)P3, D-Ins(2,3)P2 and alternatively via D-Ins(1,2,3,5,6)P5, D-Ins(2,3,5,6)P4, D-Ins(2,3,5)P3, D-Ins(2,3)P2 to finally Ins(2)P. D-Ins(2,3,5,6)P4, D-Ins(2,3,5)P3, and D-Ins(2,4)P2 were reported for the first time as intermediates of enzymatic phytate dephosphorylation. A role of the phytate-degrading enzyme from K. terrigena in phytate breakdown could not be ruled out. Because of its cytoplasmatic localization and the suggestions for substrate recognition, D-Ins(1,3,4,5,6)P5 might be the natural substrate of this enzyme and, therefore, may play a role in microbial pathogenesis or cellular myo-inositol phosphate metabolism.Key words: myo-inositol phosphate isomers, phytate-degrading enzyme, phytate, phytase, Klebsiella terrigena.
- Published
- 2006
47. Small bowel absorption of magnesium and calcium sulphate from a natural mineral water in subjects with ileostomy
- Author
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Maurice J. Arnaud, Henrik Andersson, Nils-Gunnar Carlsson, and Lena Normén
- Subjects
Adult ,Male ,Calcium intakes ,medicine.medical_specialty ,medicine.medical_treatment ,Medicine (miscellaneous) ,chemistry.chemical_element ,Calcium ,Natural mineral ,Calcium Sulfate ,Magnesium Sulfate ,Ileostomy ,Animal science ,Intestine, Small ,medicine ,Humans ,Aged ,Cross-Over Studies ,Nutrition and Dietetics ,Chemistry ,Magnesium ,Middle Aged ,Micronutrient ,Surgery ,Calcium, Dietary ,Female ,Mineral Waters - Abstract
In many developed countries, magnesium and calcium intakes do not reach recommendations for a large part of the population. Mineral water may be a useful alternative source of dietary minerals, especially in groups of people at risk for developing deficiency due to low intakes.To assess if the addition of a natural and mineral-rich water increased small bowel mineral absorption in people with ileostomy.A controlled randomised crossover study with two periods of two days each and a minimum 5 days of washout was performed in six ileostomy subjects. Apparent mineral absorption from 0.5 L of natural mineral water with either a high or a low mineral content consumed in the fasting state was compared. The daily addition of minerals corresponded to 2.3mmol magnesium, 6.9 mmol calcium and 7.7mmol sulphate. Ileostomy effluents were sampled and analysed for magnesium, calcium and total sulphate.When compared with the control, the median absorbed amount of magnesium increased from 0.8 (0-1.34) mmol/d to 1.2 (0.8-1.9) mmol/d,which corresponded to a 30% increase (P = 0.028). Median amount of calcium absorbed increased from 8.3 (6.7-13.6) mmol/d to 14.8 (8.3-20.4) mmol/d, i. e. a 45% increase (P = 0.027). The sulphate absorption increased from 1.9 (1.3-2.2) mmol/d to 5.1 (4.2-6.8) mmol/d,which corresponded to 197 % increase (P = 0.028).The mineral-rich water increased absorption of both magnesium and calcium and can therefore be used as an additional source of minerals. However, consumption with meals may be preferred.
- Published
- 2005
48. Improved iron solubility in carrot juice fermented by homo- and hetero-fermentative lactic acid bacteria
- Author
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Thomas Andlid, Sharon W. Bergqvist, Ann-Sofie Sandberg, and Nils-Gunnar Carlsson
- Subjects
Carrot juice ,biology ,Chemistry ,food and beverages ,Lactobacillus pentosus ,Cellulase ,biology.organism_classification ,Microbiology ,Lactic acid ,chemistry.chemical_compound ,Leuconostoc mesenteroides ,biology.protein ,Fermentation ,Food science ,Solubility ,Lactic acid fermentation ,Food Science - Abstract
To evaluate lactic acid fermentation as a means to increase the availability of iron in carrot juice, two strains (Lactobacillus pentosus FSC1 and Leuconostoc mesenteroides FSC2), two types of carrot juice and two modes of fermentation were compared. Fermentation improved iron solubility up to 30 fold. The total mineral content and the yield of soluble iron differed between the two types of juice. Addition of pectolytic enzyme and cellulase further improved iron solubility in fermented juice by about 10%. L. pentosus FSC1 yielded the largest improvement in soluble iron, which was not simply a result of a decrease in pH. The concentration of soluble iron in Ln. mesenteroides FSC2 fermentation was linearly related to the major acids produced. Besides, the mineral inhibitor phytate was completely degraded in all the fermentations. Lactic acid fermentation strongly improves iron solubility in carrot juice. The level of improvement was strain specific and related to the produced acids rather than a simple pH effect. Composition of carrot juice and addition of viscosity-reducing enzymes also contributed to this improvement. Our study suggests that carrot juice with high mineral availability may be achieved by fermentation using selected starter cultures, substrate and process.
- Published
- 2005
49. The pathway of dephosphorylation of myo-inositol hexakisphosphate by phytate-degrading enzymes of different Bacillus spp
- Author
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Ralf Greiner, Adelazim Farouk, Nils-Gunnar Carlsson, and Marie Alminger
- Subjects
Phytic Acid ,Bacillus amyloliquefaciens ,Immunology ,Bacillus ,Bacillus subtilis ,Applied Microbiology and Biotechnology ,Microbiology ,Dephosphorylation ,Genetics ,Phosphorylation ,Inositol phosphate ,Molecular Biology ,chemistry.chemical_classification ,6-Phytase ,biology ,Hydrolysis ,General Medicine ,Hydrogen-Ion Concentration ,biology.organism_classification ,Bacillales ,Kinetics ,B vitamins ,Metabolic pathway ,Enzyme ,Biochemistry ,chemistry - Abstract
The pathway of dephosphorylation of myo-inositol hexakisphosphate by the phytate-degrading enzymes of Bacillus subtilis 168, Bacillus amyloliquefaciens ATCC 15841, and Bacillus amyloliquefaciens 45 was established using a combination of high-performance ion chromatography analysis and kinetic studies. The data demonstrate that all the Bacillus phytate-degrading enzymes under investigation dephosphorylate myo-inositol hexakisphosphate by sequential removal of phosphate groups via two independent routes; the routes proceed via D-Ins(1,2,4,5,6)P5 to Ins(2,4,5,6)P4 to finally Ins(2,4,6)P3 or D-Ins(2,5,6)P3 and via D-Ins(1,2,4,5,6)P5 to D-Ins(1,2,5,6)P4 to finally D-Ins(1,2,6)P3. The resulting myo-inositol trisphosphate D-Ins(1,2,6)P3 was degraded via D-Ins(2,6)P2 to finally Ins(2)P after prolonged incubation times in combination with increased enzyme concentration. Key words: Bacillus spp., myo-inositol phosphate isomers, phytase, phytate degradation.
- Published
- 2002
50. Correction: Formation of reactive aldehydes (MDA, HHE, HNE) during the digestion of cod liver oil: comparison of human and porcine in vitro digestion models
- Author
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Cecilia Tullberg, Karin Larsson, Nils-Gunnar Carlsson, Irene Comi, Nathalie Scheers, Gerd Vegarud, and Ingrid Undeland
- Subjects
General Medicine ,Food Science - Abstract
Correction for ‘Formation of reactive aldehydes (MDA, HHE, HNE) during the digestion of cod liver oil: comparison of human and porcine in vitro digestion models’ by Cecilia Tullberg et al., Food Funct., 2016, 7, 1401–1412.
- Published
- 2017
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