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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

En experimentell studie av styrkepotentialen vid SCA Munksunds kraftlinertillverkning

Hortlund, Tina, Öhrvall, Mikaela January 2017 (has links)
Industrial manufacturing companies are working in a greater extent than before to optimize processes as well as reduce variation to build in quality in their products. SCA Munksund produces kraftliners with high variability for the strength measurements bursting strength and SCT-CD, together called strength potential. Variability in these strength measurements leads to either higher quality than requested by customers or to products being scrapped due to substandard quality. The variation in the strength measurements leads to unnecessary production costs according to SCA Munksund. To investigate the variation in strength measurements of a specific grammage of a kraftliner (170 g/m2), the problem-solving methodology DMAIC in Six Sigma was used. DMAIC can be used to translate a complex production problem into a more manageable statistical problem. Design of Experiments (DoE) can be used together with DMAIC to identify casual relationships and can also be applied to increase process knowledge. DoE is a powerful tool when studying how effects of multiple process parameters affect quality parameters in a process. In this master thesis, DMAIC was applied as a method to illustrate how a complex production problem can be tackled. The purpose of this master thesis work was to exemplify how statistical tools and methods can be applied in a manufacturing industry to achieve increased process knowledge. The purpose was applied practically at SCA Munksund kraftliner production site to create increased understanding of the subprocesses where the strength measurements bursting strength and SCT-CD can be affected. DMAIC was initially used to define the problem and DoE was used to generate models that could explain the strength potential. To help answer the thesis question, historical data were analysed to identify potential experimental factors. Appropriate experimental levels were checked in a test before the experiments. Then the experimental factors for bursting strength were determined to A: Läppläge vertikal topplåda, B: Alun bas and C: Koncentration inloppslåda bas and the factors for SCT-CD to A: Läppläge vertikal topplåda, B: Utloppsdifferens top and C: Utloppsdifferens bas. The experiments used a 23 factorial design with three center points. Alun bas and Utloppsdifferens top could on a 10 percent significance level be identified as significant effects. Regression models were developed to describe which factors and factor interactions that affect the strength potential in a kraftliner. The case study results thus illustrates how statistical tools and methods can be applied in a manufacturing industry to increase process knowledge. The result show that the bursting strength and SCT-CD increased with 2,4 % and 1,3 % respectively compared to normal levels during the experiment at the same time as lower operating costs can be achieved. SCA Munksund can save 143 700 SEK per year if the recommended level of Alun bas is followed. / Industriellt tillverkande företag arbetar i större utsträckning än tidigare med optimering av processer samt för minskad variation kring uppsatta toleransgränser i syfte att bygga in rätt kvalitet i sina produkter. SCA Munksund producerar kraftliner med hög variation för styrkemåtten sprängstyrka och SCT-CD. Variationen leder till att kraftlinerrullar antingen kan säljs med bättre kvalitet än efterfrågat eller så kasseras de på grund av bristande kvalitet. I båda avseendena anser SCA Munksund att variationen för styrkemåtten leder till onödiga kostnader vid produktionen. För att utreda variationen i styrkemåtten hos en specifik ytvikt av kraftliner, 170 g/m2, användes Sex Sigmas problemlösningsmetodik DMAIC som förkortat står för Define, Measure, Analyze, Improve och Control. DMAIC används för att översätta ett komplext produktionsproblem till ett mer hanterligt statistiskt problem. Inom problemlösningsmetodiken kan försöksplanering användas för att identifiera kausala samband och kan tillämpas för ökad processkunskap. Försöksplanering är ett kraftfullt verktyg för att kunna studera hur effekterna av flera processparametrar påverkar kvalitetsparametrar i en process. Vid examensarbetet användes DMAIC för att angripa ett komplext problem. Syftet med examensarbetet var att exemplifiera hur statistiska verktyg och metoder kan tillämpas inom en tillverkande industri för att nå ökad processkännedom. Syftet applicerades praktiskt vid SCA Munksunds kraftlinertillverkning för att skapa ökad förståelse inom de delprocesser där styrkepotentialen kan påverkas. DMAIC användes för att initialt kunna definiera problemet och försöksplanering användes för att skapa regressionsmodeller som kan förklara styrkepotentialen. För att uppnå syftet analyserades historisk data för att identifiera potentiella försöksfaktorer. Lämpliga försöksnivåer kontrollerades vid ett test innan experimenten. Därefter kunde försöksfaktorerna fastställas för sprängstyrkan till A: Läppläge vertikal topplåda, B: Alun bas och C: Koncentration inloppslåda bas och faktorerna för SCT-CD till A: Läppläge vertikal topplåda, B: Utloppsdifferens topp och C: Utloppsdifferens bas. Experimentet genomfördes enligt en 23 försöksplan med tre centrumpunkter. Alun bas och Utloppsdifferens toppkunde med 10 % signifikansnivå identifieras som signifikanta effekter. Anpassade regressionsmodeller skapades i syfte att beskriva vilka faktorer och samspel mellan faktorer som påverkar styrkepotentialen i kraftlinern. Fallstudien illustrerar därmed hur statistiska verktyg och metoder kan tillämpas inom en tillverkande industri för att nå ökad processkännedom. Jämfört mot normala nivåer visar resultaten från de experiment som genomfördes i fallstudien att sprängstyrkan ökade med 2,4 % och SCT-CD med 1,3 % samtidigt som lägre driftskostnader kan uppnås. Efterföljs den rekommenderade nivån för alun i kraftlinerns basskikt leder det till en besparing på 143 700 SEK per år. Besparingen av alun är endast beräknad på den studerade kraftlinern med ytvikt 170 g/m2, vilket innebär att ytterligare besparingar bör vara möjliga för resterande 18 ytvikter.
82

Uso da cromatografia líquida de alta eficiência acoplada à espectrometria de massas sequencial para determinação do perfil de eicosanoides em plasma após estimulação: comparação entre pacientes com anemia falciforme e indivíduos saudáveis / High performance liquid chromatography coupled with tandem mass spectrometry to investigate eicosanoid profile in peripheral blood after stimulation: comparison between sickle cell anemia patients with healthy individuals

Alyne Fávero Galvão Meirelles 24 March 2016 (has links)
Os eicosanoides, produtos do metabolismo do ácido araquidônico, apresentam papel importante na homeostasia e na patogênese de diversas doenças humanas. A biossíntese desses compostos pode ser estimulada por agentes farmacológicos como ionóforos e inibidores da Ca2+-ATPase, e também por agonistas naturais como o formil-metionil-leucil-fenialanina (fMLP). Considerando os interesses em avaliar e comparar o perfil de mediadores lipídicos, como os leucotrienos (LTs), as prostaglandinas (PGs), os ácidos epoxieicosatrienoicos (EETs), os ácidos dihidroxitetraenoicos (DiHETEs) e os ácidos hidroxieicosatetraenoicos (HETEs), na saúde e na doença, o objetivo deste trabalho foi padronizar um método analítico para determinar do perfil de eicosanoides em plasma humano após estimulação do sangue total, e assim observar diferenças entre indivíduos saudáveis e doentes. Dessa forma, um método por cromatografia líquida de alta eficiência acoplada à espectrometria de massas sequencial (HPLC-MS/MS) foi validado para quantificação de 22 eicosanoides em plasma de indivíduos saudáveis. A análise por HPLCMS/ MS foi realizada em modo negativo pelo modo de varredura por monitoramento de reações múltiplas (MRM). A linearidade do método apresentou coeficiente de correlação (r) maior que 0,98 para todos os eicosanoides analisados. A precisão e exatidão intra e inter-ensaios tiveram desvio padrão e erro relativo menores que 15%, exceto para o limite inferior de quantificação cujos valores foram menores que 20%. Para estimulação das células do sangue total, quatro estímulos (fMLP, ionomicina, A23187 e tapsigargina) foram utilizados. A análise estatística mostrou que o A23187 e a tapsigargina foram os estímulos mais potentes na indução da produção de eicosanoides. Em seguida, comparamos o perfil de eicosanoides em amostras de plasma de indivíduos saudáveis com pacientes com anemia falciforme (AF), em tratamento com hidroxiureia (HU) ou transfusão sanguínea crônica. Os resultados demonstraram que o método é preciso para determinação de diferenças entre os pacientes e indivíduos saudáveis quanto à produção dos mediadores lipídicos 5-HETE, 12-HETE, LTB4, LTE4, TXB2 e PGE2. Portanto, nosso método analítico é sensível, específico e reprodutível para identificar e quantificar diferenças no perfil de eicosanoides em amostras de sangue estimuladas in vitro, e poderá contribuir para o estabelecimento do perfil de mediadores lipídicos em diferentes doenças inflamatórias e infecciosas. / Eicosanoids, products from arachidonic acid metabolism, play an important role in the homeostasis and in the pathogenesis of various human diseases. Pharmacological agents such as Ca2+ ionophores and Ca2+-ATPase inhibitors, as well as natural agonists such as fMet-leu-Phe (fMLP) can stimulate eicosanoid biosynthesis. Considering the interests in evaluate and compare the profile of lipid mediators, as leukotriens (LTs), prostaglandins (PGs), epoxyeicosatrienoic acids (EETs), dihydroxytetraenoic acids (DiHETEs) and hydroxyeicosatetraenoic acids (HETEs), in healthy and disease, the aim of this work was to standardize a method to determine the eicosanoid profile of human plasma samples after whole blood stimulation, and to assess differences between healthy and sick individuals. For this purpose, a liquid chromatographytandem mass spectrometry (LC-MS/MS) method was validated for the quantification of 22 eicosanoids using human plasma from healthy volunteers. In addition, we optimized a method for the stimulation of eicosanoids in human whole blood. LC-MS/MS analyses were performed by negative electrospray ionization and multiple reaction monitoring. An assumption of linearity resulted in a regression coefficient > 0.98 for all eicosanoids tested. The mean intra-assay and inter-assay accuracy and precision values had relative standard deviations and relative errors of < 15%, except for the lower limit of quantification, where these values were < 20%. For whole blood stimulation, four stimuli (fMLP, ionomycin, A23187, and thapsigargin) were used. Results of the statistical analysis showed that A23187 and thapsigargin were potent stimuli to induce the production of eicosanoids. We next compared the eicosanoid profiles of healthy volunteers to those of patients with sickle cell anemia (SCA) under treatment with hydroxyurea (HU) or after chronic red blood cell (RBC) transfusion. The results indicate that the method was sufficient to find a difference between lipid mediators released in whole blood of SCA patients compared to healthy subjects for 5-HETE, 12-HETE, LTB4, LTE4, TXB2, and PGE2. In conclusion, our analytical method is sensitive, specific and reproducible for indentify and quantify changes in eicosanoid profiles in whole blood stimulated in vitro, which can contribute to establishing the eicosanoid profiles associated with different inflammatory and infectious diseases.
83

Impact of ALCAM (CD166) on homing of hematopoietic stem and progenitor cells

Aleksandrova, Mariya Aleksandrova 18 December 2012 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / The potential of hematopoietic stem cells (HSC) to home and to anchor within the bone marrow (BM) microenvironment controls the ability of transplanted HSCs to establish normal hematopoiesis. Activated Leukocyte Cell Adhesion Molecule (ALCAM; also identified as CD166), which participates in homophilic interactions, is expressed on a group of osteoblasts in the hematopoietic niche capable of sustaining functional HSC in vitro. Since we could also detect ALCAM expression on HSC, we suspect that ALCAM may play a role in anchoring primitive hematopoietic cells to ALCAM expressing components of the hematopoietic niche via dimerization. We investigated the role of ALCAM on the homing abilities of hematopoietic stem and progenitor cells (HSPC) by calculating recovery frequency of Sca-1+ALCAM+ cells in an in vivo murine bone marrow transplantation model. Our data supports the notion that ALCAM promotes improved homing potential of hematopoietic Sca-1+ cells. Recovery of BM-homed Sca-1+ cells from the endosteal region was 1.8-fold higher than that of total donor cells. However, a 3.0-fold higher number of Sca-1+ALCAM+ cells homed to the endosteal region compared to total donor cells. Similarly, homed Sca-1+ALCAM+ cells were recovered from the vascular region at 2.1-fold greater frequency than total homed donor cells from that region, compared to only a 1.3-fold increase in the recovery frequency of Sca-1+ cells. In vitro quantitation of clonogenic BM-homed hematopoietic progenitors corroborate the results from the homing assay. The frequency of in vitro clonogenic progenitors was significantly higher among endosteal-homed Sca-1+ALCAM+ cells compared to other fractions of donor cells. Collectively, these data demonstrate that engrafting HSC expressing ALCAM home more efficiently to the BM and within the BM microenvironment, these cells preferentially seed the endosteal niche.
84

Doing Good While Being Good : A study of the relationship between Corporate Social Responsibility and the Swedish Companies Act

Djäken, Johan January 2016 (has links)
This thesis investigates the current interrelationship between the provisions contained in the Swedish Company Act (2005:551) and activities related to Corporate Social Responsibility (CSR) pursued by companies listed at Nasdaq Stockholm. The focal point of this thesis could be argued to be of particular relevance in this day and age, as companies listed at Nasdaq Stockholm continue to perform at the top of the league in global sustainability performance measurements, and Swedish and European legislators have intensified their efforts to encourage businesses to operate in a way that does not incur unacceptable social costs to society. Thus, most companies, particularly those with a vested interest in the private consumer market, seem to recognise the importance of fostering long-term relationships with a wide sphere of stakeholders. The purpose of the thesis has been to contribute to the steadily increasing body of legal research that discusses to what extent Swedish companies, without breaching corporate law, could involve themselves in CSR investments. Since I, initially, conclude that Swedish publicly listed companies seem to increasingly invest in activities related to CSR, the thesis also discusses whether the relevant provisions of the SCA need to change to better adapt to companies’ involvement in CSR activities. In brief, I argue, that current business research on CSR coupled with the aforementioned relevant provisions of the SCA allow boards and managing directors to pursue practically any CSR investments, and that shareholders are mostly restricted to rely on relatively blunt ex post actions against a board and/or managing director that has pursued an ill-considered CSR investment, including the obvious choices of voting to replace the board or selling their shares. And since current business research has not consistently proven the positive impact of CSR policies on the financial performance of businesses there are reasons to suspect that the law practically, due to the shielding force of the business judgment rationale and the legislator’s wish to protect most transactions, cannot be effectively applied to stop CSR investments, even if these are nothing but costs for the business. On the other hand, the findings of the thesis also suggest that the occurrence of such unwise CSR investments is not necessarily a proliferating problem, since many companies listed at Nasdaq Stockholm nowadays have powerful and short-sighted institutional owners. The situation might therefore very well be the opposite and that executives struggle to manage for the long-term, as the logic of the market tell them to do otherwise. / Den här examensuppsatsen utforskar förhållandet mellan några av aktiebolagslagens regler och det engagemang som bolag noterade på Nasdaq Stockholm uppvisar i frågor rörande Corporate Social Responsibility (CSR). Ämnet kan sägas vara särskilt relevant då såväl det samtida näringslivet som lagstiftaren tycks präglas av en ökad medvetenhet kring CSR-frågor. Den ökade medvetenheten i näringslivet förefaller alltmer inverka på affärsbeslut, ett faktum som inte minst avspeglas i de svenska bolagens topplaceringar i globala index som mäter bolags arbete med hållbarhetsfrågor. Samtidigt speglas lagstiftarens ökade medvetenhet av allt fler svenska som europeiska regulatoriska initiativ på området och vars yttersta syfte är att uppmuntra och stimulera hållbara företag som inte pådyvlar samhället oacceptabla sociala kostnader. Det är således inte särskilt anmärkningsvärt att bolagen, i synnerhet de med intressen anknutna till konsumentmarknaderna, tycks erkänna vikten av att bygga och underhålla långsiktiga relationer med en vidare krets av intressenter än deras aktieägare. Det är min förhoppning att den här uppsatsen kommer att bidra till den ständigt växande del av den aktiebolagsrättsliga diskursen som diskuterar till vilken grad bolag, utan att handla i strid med ABL:s bestämmelser, kan företa åtgärder kopplade till CSR. Eftersom jag inledningsvis anför att bolagen på Nasdaq Stockholm tycks ägna sig allt mer åt CSR diskuterar också uppsatsen om några av ABL:s bestämmelser bör förändras för att bättre hantera dessa företags allt större engagemang i CSR-frågor. Sammanfattningsvis argumenterar jag för att nuvarande företagsekonomisk forskning kring CSR tillsammans med de aktuella bestämmelsernas juridiska innebörd innebär att såväl bolagsstyrelser som verkställande direktörer kan företa i princip vilken investering relaterad till CSR som helst. Aktieägare är i praktiken hänvisade till att söka åstadkomma långsiktigt lönsamma satsningar på hållbarhet genom sanktioner ex post, exempelvis genom att sälja sina aktier eller rösta bort styrelsen. Detta innebär å ena sidan i praktiken, med tanke på att nuvarande företagsekonomisk forskning kring CSR:s inverkan på bolags vinster är tvetydig, att de relevanta bestämmelserna i ABL såsom de nu är utformade utgör en trygg hamn även för många av de transaktioner relaterade till CSR som är direkt värdeförstörande. Å andra sidan argumenterar jag i uppsatsen för att problemet med överinvesteringar i CSR inte nödvändigtvis behöver vara särskilt utbrett då bolagen och deras bolagsstyrning allt mer kommit att präglas av kortsiktiga investeringsperspektiv.

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