1,139 research outputs found
Compilation of life cycle assessments of cultivated blue mussels
With a growing world population there is an increased demand of sustainable and nutritious food. There is not much more land to farm on whether for food or for feed for livestock. Aquaculture increases more than any other production method, however there is still often a need for feed. Mussels are low trophic species that grow without input of feed, additives and antibiotics. They are filter feeding organisms consuming planktonic particles. Therefore, when harvested, nutrients are removed from the environment, reducing eutrophication. Life cycle assessment is a standardised method of calculating environmental impact.
The goals of this thesis were to compile life cycle assessments about cultivated blue mussels through a literature review and to recalculate the carbon footprint and the marine eutrophication potential. The inventory assessments of six published mussel LCA studies and one dataset were analysed. Harmonization of methodologies was performed and a uniform functional unit of one tonne of Blue mussels produced was chosen.
The recalculation resulted in a mean of 0,95 kg CO2-equivalents/kg mussel with shells at harvest and 5 mg N-equivalents/kg produced of mussels with shells at harvest. Hotspots identified were production of material used in cultivation, followed by energy and fuel use. Even though mussels have a low environmental impact, using more energy efficient boats or farmers sharing vessels could further reduce the emissions. Mussels have a high nutritional value and are relatively sustainable, making them an interesting future food product or ingredient in new products
Total carbon sequestration during an entire rotation period of oil palm in northern Borneo
Considerable amounts of carbon (C) has been lost from tropical forests as a result of continuous conversion of tropical forests into oil palm plantations. Therefore, a better understanding of the C budget and potential sequestration rate in oil palm plantations and how it compares to natural forests is needed. Which is crucial in order to provide a more reasonable C credit payment to limit the widespread land conversion of tropical forests to oil palm plantations. In this thesis, I quantified the amount of C in both above- and belowground pools, which included: aboveground oil palms, stumps, senesced fawns, fine litter, coarse woody debris, roots and soil over an entire rotation period of oil palm. I established 12 plots of similar conditions within a chrono sequence of oil palm, spanning from recently planted plantations <1 year old to a 22 year old plantation. Using this approach, I was able to calculate the carbon sequestration rate during an entire rotation period of oil palm as well as assess changes in different carbon pools. I estimated that 160-ton C ha-1 is lost when converting a secondary forest in Sabah Borneo to oil palm plantations. However, I found that rate of C sequestration (ton C ha-1 yr-1) in oil palm is considerably higher than C sequestration in primary and secondary tropical forests. Aboveground oil palm and soil C are the two major C pools in oil palm plantation, yet it is changes in aboveground oil palm during the rotation period that is responsible for the high C sequestration rate. I also estimated an economic profit of 37,333 USD during a rotation period based on data from the production of fresh fruit bodies. Comparing the profit to the difference in C sequestration between natural forests and oil palm plantation I calculated a C credit payment of 54-96 USD ton-1 CO2 that would be need to conserve carbon in tropical forests while at the same time provide the same economic revenue as oil palm production , which is considerably higher than the current price for C. Thus, if we want to limit the conversion of tropical forest to oil palm plantations the current C credit payment is not enough and addition payments for other ecosystem services (i..,e biodiversity and water quality) are needed.En betydande mängd kol har försvunnit från tropiska skogar som ett resultat av kontinuerlig konvertering av tropiska skogar till oljepalmsplantage. På grund av detta behövs en bättre förståelse för kollager och potentiell kolbindning i oljepalmsplantage samt hur det skiljer sig från naturlig skog. Vilket är väsentlig för att skapa ett mer resonabelt pris på kolkrediter för att begränsa konverteringen av skog till oljepalmsplantage. I denna uppsatts har jag kvantifierat mängden kollager i både ovan och under mark, vilket inkluderade oljepalmer, stubbar, avskurna oljepalmslöv, förna, död ved, rötter och jord under en hel rotation av första generations oljepalm. Jag etablerade 12 ytor med likande förhållanden med en krono sekvens av oljepalm, från nyligen planterat <1 år till 22år gammal plantage. Med hjälp av detta kunde jag räkna ut kolbindningen under en hel rotation av oljepalm samt uppskatta förändringar i de olika kollagren. Jag uppskattar att 160-ton kol ha-1 försvinner när en sekundär skog i Sabah Borneo konverteras till oljepalmsplantage. Dock så fann jag att kolbindningen i oljepalmsplantage är betydligt högre än i primär och sekundär skog. Kol i oljepalmerna och jorden är de två största kollagren i oljepalmsplantage, men det är förändringar i oljepalmerna som driver kolbindningen. Jag uppskattar en ekonomisk vinst på 37,333 USD under en rotationsperiod baserat på fruktproduktionen. Genom att jämföra vinsten emot skillnaden i kolbindning och lager för sekundär samt primär skog så uppskattar jag att priset på kolkrediter ska vara 54-96 USD ton-1 CO2 för att bevara kollagren i tropisk skog men ge samma ekonomiska vinst som oljepalmsplantage, vilket är betydligt högre än det nuvarande priset. Således om vi vill begränsa konverteringen av tropiska skogar till oljepalmsplantage så räcker inte det med de nuvarande kolkrediterna, utan ytterligare betalning för andra ekosystemstjänster (ex. biodiversitet och vattenkvalitet) behövs
The puzzle and politics of historical reconstruction: The case of the rise and development of Christianity and Judaism
This essay focuses on the topic of the emergence of Christianity and Judaism as related but distinct religious traditions, as an example of a process of religious and cultural change, which has had an enormous impact on Western and other societies around the world. At the heart of this question lies what appear to be contradictions between normative practices in antiquity and those we know of today, leading us to consider the historical and hermeneutical issue of continuity and change over time; its how, when and why. Rejecting the idea that theological differences between Judaism and Christianity necessitated a ‘parting of ways’ between them, it is argued that social, political and colonial decision-making was essential to this process, and that, furthermore, a historical focus on institutional realities in the ancient Mediterranean world, including in Jewish society, will challenge many long-held assumptions about the origins not only of Christianity but also of Judaism. The general historical reconstruction offered is then applied to a specific archaeological site, Capernaum, showing how traces of the larger pattern of development from the first to the fifth century CE may be seen in the histories of two buildings in this town
Consequences of kidney dysfunction in the community : health care-based epidemiological studies from the Stockholm creatinine measurements (scream) project
Chronic kidney disease (CKD) is affecting an increasing share of the world’s population, and
presents a global health problem. The prevalence of CKD in society and its implication for
various health outcomes have been difficult to assess due to unawareness and underuse of
clinical diagnoses for CKD in clinical practice. The present work aims to inform the reader of
the epidemic of CKD in Sweden through a newly created repository of health care data.
Paper I describes the creation of the Stockholm CREAtinine Measurements (SCREAM)
project, a health care extraction containing all creatinine values collected between 2006 and
2011 in the Stockholm region, together with a host of associated laboratory data, dispensed
prescriptions, and diagnostic and demographic information. SCREAM has a good
representation of the general population of Stockholm county, particularly of the elderly, with
a coverage exceeding 90% among persons aged 65 or above. The coverage of people with
diabetes was 98%, and that of ischemic heart disease was 97%. SCREAM captured 89% of
deaths occurring in the region those years.
Paper II investigates how causes of death correlate with estimated glomerular filtration rate
(eGFR) in the last year of life. We observed a higher proportion of death from cardiovascular
disease and infections with lower eGFR. Among cardiovascular causes, heart failure and
arrhythmias became more common with lower eGFR. Diabetes complications were also more
common in lower kidney function strata.
Paper III evaluates the association between kidney function and the risk of incident fractures
among people with CKD stages 3-5 (not on dialysis), and whether developing a fracture
predicts subsequent risk of death or major cardiovascular adverse events (MACE). We found
a gradual increase in the risk of fractures with lower eGFR in persons with CKD 3b-5 (HR 2.47
(1.94- 3.15) for hip fractures and 1.50 (1.25- 1.80) for non-hip fractures, in CKD 5 vs CKD
3a). In the aftermath of a fracture, mortality and MACE incidence were considerably increased,
in both short (= 90 days) follow-up, as compared to non-fracture
periods.
Paper IV investigates the risk and severity of hypoglycaemia in relation to kidney function,
among people with diabetes followed in outpatient care. We observed a significant, gradual
rise in the multivariable-adjusted risk of hypoglycaemia with lower eGFR. Several other risk
factors for hypoglycaemia were identified, among them type 1 diabetes, presence of diabetic
complications, and liver diseases. The risk of fatal hypoglycaemia was also higher with lower
eGF
Lessons from a Small-scale Observational Study - An Example of the Teaching of Fractions
The aim of this paper is to demonstrate what a small-scale project can tell about
features of teaching and learning in two different cultures. We argue that some
features, which may not be easily observed within one culture, can become more
visible in the contrast in order to get a better understanding of the teaching practice
per se, even from a small scale project. We have studied the mathematics teaching in
one classroom in Hong Kong and four in Sweden. Based on the assumption, that how
the content is taught has an important implication on what students may possibly
learn, we compared how the teaching of the same topic (fraction) may differ between
the two places. Some profound differences regarding how the same topic was dealt
with in the two countries were found. In the Hong Kong data several things were
handled in one lesson at the same time whereas in the Swedish data this happened in
a sequence of lessons spreading over a substantial period.published_or_final_versio
Quality - a Consequence of Organizational Culture
Issue of study: Quality Systems are frequently used within companies. These systems can be useful to make companies more efficient. The successfulness of the implementation of these systems varies between organizations. The key to quality success has been proved to be a change in the employees’ attitude and behavior. These changes are difficult to make and must start at the top level and thereafter be spread throughout the organization. Aim: The aim of this study is to identify the critical success factors for the creation of behaviors, which are favorable for quality. This study also aims to present how these factors are related. Method: This is a qualitative case study which is done out of an abductive approach. The empirical data is gathered, at the case company, by interviews, observations and reviews of internal documents. Conclusion: The critical success factors for quality are; Leadership, Quality Department, Training, Peer Involvement, Employee Ownership, Incentives, Data and Reporting, and Supplier Management. The factors’ relations show their contribution to quality and are presented in a model, where Leadership and Employee Ownership are of biggest importance
Computational homogenization of liquid-phase sintering with seamless transition from macroscopic compressibility to incompressibility
Liquid phase sintering of particle agglomerates is modeled on the mesoscale as the viscous deformation of particle-particle contact, whereby the single driving force is the surface tension on the particle/pore interface. On the macroscale, a quasistatic equilibrium problem allows for the prediction of the shrinkage of the sintering body. The present paper presents a novel FE2 formulation of the two-scale sintering problem allowing for the transition to zero porosity, implying macroscale incompressibility. The seamless transition from compressibility to incompressibility on the macroscale is accomplished by introducing a mixed variational format. This has consequences also for the formulation of the mesoscale problem, that is complemented with an extra constraint equation regarding the prolongation of the volumetric part of the macroscopic rate-of-deformation. The numerical examples shows the sintering of a single representative volume element (RVE) which is sheared beyond the point where the porosity vanishes while subjected to zero macroscopic pressure. © 2013 The Authors
Different possibilities to learn from the same task
In this paper we focus on variation of the design and the implementation of a specific task during three mathematics lessons in the 8th grade in a learning study (Marton & Tsui, 2004; Runesson, 2008). The theme of the lesson was division, with a denominator between 0 and 1. The teachers wanted their students to understand that when dividing with a denominator less than 1, the quotient is larger than the numerator. Four teachers collaboratively planned, analyzed and revised three lessons in a cyclic process. The study shows that the implementation of the task changed between the lessons. Although the same task was used in the lessons, the way it was enacted provided different possibilities to learn
Diferentes posibilidades para aprender con una misma tarea
In this paper we focus on variation of the design and the implementation of a specific task during three mathematics lessons in the 8th grade in a learning study (Marton & Tsui, 2004; Runesson, 2008). The theme of the lesson was division, with a denominator between 0 and 1. The teachers wanted their students to understand that when dividing with a denominator less than 1, the quotient is larger than the numerator. Four teachers collaboratively planned, analyzed and revised three lessons in a cyclic process. The study shows that the implementation of the task changed between the lessons. Although the
same task was used in the lessons, the way it was enacted provided different possibilities to learn.En este artículo nos centramos en la variación del diseño y la implementación de una tarea específica durante tres sesiones de clase de matemáticas en octavo grado en un estudio de aprendizaje (Marton y Tsui, 2004; Runesson, 2008). El tema de las clases fue la división con un divisor entre 0 y 1. Los
profesores querían que sus estudiantes entendieran que, cuando se divide por
un divisor menor que 1, el cociente es mayor que el numerador. Cuatro profesores colaboraron, en un proceso cíclico, en la planificación, análisis y revisión de las tres sesiones de clase. El estudio muestra que la implementación de la tarea cambió entre las sesiones. A pesar de utilizarse la misma tarea en las sesiones, la manera en que se implementó proporcionó diferentes posibilidades para aprender.This research was funded by a grant from the Swedish National Research Council
Atomistic-to-continuum coupling based on goal-oriented adaptivity and quasi-continuum approximation
It has long been understood that some of the key characteristics of materials, like grain boundaries, dislocation cores, and crack tips cannot be modeled realistically within the framework of continuum mechanics. It is believed that defects and surface effects play important roles at small scales, where the continuum assumptions are violated. Therefore, further information on a material at its atomic scale is required to give a more physically based description of the phenomena governing the macroscopic behavior. A well-established method for concurrent coupling between atomistic and continuum regions is the quasi-continuum (QC) method. Basically, it relies on the fact that in many practical cases, only a small region in the material needs to be modeled atomistically. As a result, the assumptions of continuum mechanics can still be adopted for modeling the remaining regions without loss of the accuracy. This strategy provides a significant gain in computational cost, whereas the interesting phenomena pertaining to the atomistic area are also preserved. In this study, atomistic-to-continuum homogenization of molecular statics problem has been advanced with particular focus on the effect of lattice defects. A representative unit lattice (RUL) with Cauchy–Born boundaries is considered for obtaining homogenized response of the graphene lattice in terms of membrane forces (macroscale stress). In order to facilitate such an analysis, an adaptive strategy based on goal-oriented error estimation is developed for retaining the accuracy in the “goal-quantity” or “quantity of interest”, chosen to be the macroscale (continuum) stress. The QC method is introduced in two steps. First, we consider the restriction of atom displacement in terms of the representative atoms as a model reduction. The second step in the QC method is that of quadrature. For large QC elements, i.e., for a large amount of atoms whose placements are governed by the same representative atoms, the bond energy and its derivatives are typically computed using an appropriate discrete quadrature. We show how cluster approximation generates a quadrature error (in addition to the discretization error). Error because of different sources, namely: interpolation and quadrature parts of the QC method is approximated by solving the pertinent dual (adjoint) problem relevant to the output of interest. A hierarchical strategy is proposed for approximating the residual on an intermediate mesh, thus avoiding high computational cost that pertains to solving the full system. Homogenization of the macroscale membrane forces, including initial relaxation, is considered for the graphene in presence of divacancy defect. The Carbon–Carbon interactions are modeled via the Tersoff–Brenner potential enabling computation of bond energies up to the next nearest neighbor. The reliability of the adaptive algorithm is demonstrated through the numerical simulations on the respective RUL under macroscopic deformation.Further, we present an extension of the coupling methodology by developing strategies to obtain a macroscopically relaxed RUL. The RUL with Cauchy–Born boundaries is relaxed in a (nested) iterative procedure so that the macroscopic stress becomes zero for a certain equilibrium configuration. A stress–strain (i.e., membrane forces) response originating from macroscopically relaxed configuration is derived in two steps. The first step results in a stress-free configuration by finding a deformation map that corresponds to zero effective stress response. The subsequent step involves a multiplicative decomposition of the deformation and the pertinent push-forward of the effective stress
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