26 resultados para SECONDARY METABOLISM
Resumo:
Centrala teman i min avhandling är parallellskolesystem, linjedelning och segregering i högstadier och gymnasier. Det finns stora skillnader mellan länder gällande den årskurs då eleverna sorteras in i olika nivåer genom skilda klasser eller skolor. I Tyskland och Nederländerna till exempel delas eleverna upp före högstadiet medan Sverige och Finland har enhetsskolor på högstadienivå. Jag argumenterar att parallellskolesystem har en positiv effekt på elevernas testresultat i årskurserna före linjedelningen. Eleverna har incitament att jobba hårdare för att komma på i den akademiska linjen. Jag undersöker incitamentseffekter empiriskt, och hittar mönster konsistenta med incitamentseffekter både i brittisk och i internationell data. Det andra bidraget i avhandlingen är metodologiskt. Nationalekonomer brukar behandla testresultat från t.ex. IQ-tester eller internationella PISA-undersökningar som om absoluta nivån på poängantalen har betydelse i sig. I verkligheten antyder de endast en rangordning. Jag visar att normalfördelade testresultat i många fall ligger tillräckligt nära dess pengavärde på arbetsmarknaden för att ändå kunna tolkas som absoluta.
Resumo:
Tutkin pro gradu -tutkielmassani englannin kielen oppijoiden pragmaattista kompetenssia. Tarkoitukseni oli selvittää, miten suomalaiset yläkoululaiset ja lukiolaiset osaavat käyttää englannin kieltä erilaisissa kommunikaatiotilanteissa. Tutkielmani voidaan sijoittaa välikielen pragmatiikan tutkimukseen. Halusin selvittää, millä tasolla suomalaisten oppijoiden pragmaattinen kompetenssi on ja kehittyykö se yläkoulun ja lukion välillä. Lisäksi tutkin, vaikuttavatko oppimisympäristö ja oppimismahdollisuudet oppijoiden kykyyn käyttää englannin kieltä. Toisin sanoen vertasin englantipainotteisilla luokilla olevia oppilaita formaalin opetuksen oppijoihin sekä tutkin, vaikuttavatko englanninkieliset vapaa-ajan aktiviteetit ja oppijoiden mahdolliset oleskelut englanninkielisissä maissa heidän pragmaattiseen kompetenssiinsa. Tutkimukseni kohderyhmä koostui yläkoulun kahdeksasluokkalaisista ja lukion toisen vuosikurssin opiskelijoista. Testasin neljä eri ryhmää, joissa oli sekä formaalissa opetuksessa olevia oppijoita (yksi ryhmä kahdeksasluokkalaisia ja yksi ryhmä toisen vuosikurssin opiskelijoita) että kielipainotteisten luokkien oppijoita (yksi ryhmä kahdeksasluokkalaisia ja yksi ryhmä toisen vuosikurssin opiskelijoita). Arvioin kohderyhmäni pragmaattista kompetenssia monivalintatestillä, jossa testattiin oppijoiden kykyä käyttää ja ymmärtää implikaatioita, tilannekohtaisia rutiineja sekä puheakteja. Taustakysymysten avulla selvitin, kuinka usein oppijat käyttivät englantia vapaa-aikanaan ja olivatko he vierailleet englanninkielisissä maissa. Tutkimustulokseni osoittavat, että suomalaisten yläkoululaisten ja lukiolaisten pragmaattinen kompetenssi oli korkea. Pragmaattinen kompetenssi kehittyi kahdeksasluokkalaisten ja lukion toisen vuosikurssin välillä. Kehitys oli suurempaa formaalissa opetuksessa kuin kielipainotteisilla luokilla. Englantipainotteisilla luokilla olevat oppilaat suoriutuivat testistä paremmin kuin formaalin opetuksen oppilaat. Tosin erot olivat tilastollisesti merkitseviä vain yläkoulussa. Tutkimuksessani siis päättelin, että vieraskielinen opetus vaikutti enemmän nuorempiin oppijoihin. Eri oppimismahdollisuudet osoittautuivat haastaviksi analysoida. Tulokset osoittivat, että vain englanninkielisessä maassa oleskelulla oli vaikutusta oppijoiden pragmaattiseen kompetenssiin. Kysyttäessä vapaa-ajan aktiviteettien merkitystä oppijat kuitenkin kertoivat, että ne auttoivat heitä testiin vastaamisessa enemmän kuin englanninopetuksessa käydyt asiat. Kouluissa tulisikin jatkossa painottaa yhä enemmän vuorovaikutteista kieltenopetusta.
Resumo:
Temat för studien handlar om gymnasielärares uppfattningar om kvalitet och om hur kvalitet kan utvecklas i gymnasieutbildningen in Tanzania. Studien är till sin karaktär kvalitativ och består av utprövade semistrukturerade intervjuer med sammanlagt trettio lärare som arbetar i fyra gymnasieskolor både i urbana och rurala miljöer. Lärarna har varierande arbetserfarenhet och undervisar i olika ämnen. Huvudfokus har gällt identifieringen av variationer i lärares uppfattningar om kvalitet. På basen av två forskningsfrågor avslöjar analysen uppfattningar av hur lärare förstår och önskar utveckla kvaliteten på gymnasieutbildningen. Resultaten visar att lärare förstår kvaliteten på utbildningen i sina skolor som försök att möta skolans och samhällets mål, som individuella prestationer och förmågor som att inneha kompetenser och som att möta utmaningar inom utbildning, Identifierade uppfattningar var baserade på lärarnas personliga kunskap, arbetsmiljön och varierande omständigheter som rådde i deras skolor. Uppfattningar om en förbättring av kvaliteten i gymnasieutbildningen innefattade utveckling av lärares motivation, skolmiljön, arbetet i klassrum, kvaliteten på lärares kunskaper och färdigheter och undervisningsmaterial. Ambitionen bakom studien ar att erbjuda en plattform för strategier för att förbättra kvaliteten på gymnasieutbildningen. Resultaten strävar till att ge en fördjupad insikt i uppfattningar hos en utvald grupp av lärare som arbetar under samma villkor inom gymnasieskolor I Tanzania. Av den här anledningen är den genererade kunskapen därför relevant för att belysa lärares uppfattningar även utanför den studerade gruppen av respondenter.
Resumo:
Background: The m.3243A>G mutation in mitochondrial DNA is the most common cause for mitochondrial diabetes. In addition, unexpected deaths related to the m.3243A>G associate with encephalopathy and cardiomyopathy. Failing mitochondrial respiratory chain in neurons, myocytes and beta cells is considered to underlie the multiorgan manifestations of the m.3243A>G. Aims: The primary aim of the study was to characterize the organ-specific glucose metabolism in patients with m.3243A>G and secondly, to study patients with or without signs of diabetes, cardiomyopathy or encephalopathy. The insulin-stimulated glucose metabolism in brain, heart, skeletal muscle, adipose tissue and liver were measured with 2-deoxy-2-[18F]fluoro-α-D-glucose in 15 patients and 14 controls. Brain oxygen metabolism was assessed with [15O]oxygen and insulin secretion was modelled based on oral glucose tolerance test. Results: The glucose oxidation in brain was globally decreased in patients with or without clinical encephalopathy. The insulin-stimulated glucose influx to skeletal muscle and adipose tissue was decreased in patients with or without diabetes as the hepatic glucose metabolism was normal. Impaired beta cell function and myocardial glucose uptake were associated with the high m.3243A>G heteroplasmy. Conclusions: This cross-sectional study suggests that: 1) The ability of insulin to stimulate glucose metabolism in skeletal muscle and adipose tissue is weakened before the beta cell failure results in mitochondrial diabetes. 2) Glucose oxidation defect is detected in otherwise unaffected cerebral regions in patients with the m.3243A>G, thus it likely precedes the clinical encephalopathy. 3) Uneconomical glucose hypometabolism during hyperinsulinemia contributes to the cardiac vulnerability in patients with high m.3243A>G heteroplasmy
Resumo:
Rapid changes in biodiversity are occurring globally, as a consequence of anthropogenic disturbance. This has raised concerns, since biodiversity is known to significantly contribute to ecosystem functions and services. Marine benthic communities participate in numerous functions provided by soft-sedimentary ecosystems. Eutrophication-induced oxygen deficiency is a growing threat against infaunal communities, both in open sea areas and in coastal zones. There is thus a need to understand how such disturbance affects benthic communities, and what is lost in terms of ecosystem functioning if benthic communities are harmed. In this thesis, the status of benthic biodiversity was assessed for the open Baltic Sea, a system severely affected by broad-scale hypoxia. Long-term monitoring data made it possible to establish quantitative biodiversity baselines against which change could be compared. The findings show that benthic biodiversity is currently severely impaired in large areas of the open Baltic Sea, from the Bornholm Basin to the Gulf of Finland. The observed reduction in biodiversity indicates that benthic communities are structurally and functionally impoverished in several of the sub-basins due to the hypoxic stress. A more detailed examination of disturbance impacts (through field studies and -experiments) on benthic communities in coastal areas showed that changes in benthic community structure and function took place well before species were lost from the system. The degradation of benthic community structure and function was directed by the type of disturbance, and its specific temporal and spatial characteristics. The observed shifts in benthic trait composition were primarily the result of reductions in species’ abundances, or of changes in demographic characteristics, such as the loss of large, adult bivalves. Reduction in community functions was expressed as declines in the benthic bioturbation potential and in secondary biomass production. The benthic communities and their degradation accounted for a substantial proportion of the changes observed in ecosystem multifunctionality. Individual ecosystem functions (i.e. measures of sediment ecosystem metabolism, elemental cycling, biomass production, organic matter transformation and physical structuring) were observed to differ in their response to increasing hypoxic disturbance. Interestingly, the results suggested that an impairment of ecosystem functioning could be detected at an earlier stage if multiple functions were considered. Importantly, the findings indicate that even small-scale hypoxic disturbance can reduce the buffering capacity of sedimentary ecosystem, and increase the susceptibility of the system towards further stress. Although the results of the individual papers are context-dependent, their combined outcome implies that healthy benthic communities are important for sustaining overall ecosystem functioning as well as ecosystem resilience in the Baltic Sea.
Resumo:
The human body eliminates foreign compounds primarily by metabolizing them to hydrophilic forms to facilitate effective excretion through the kidneys. Cytochrome P450 (CYP) enzymes in the liver and intestine contribute to the metabolism of many drugs. Pharmacokinetic drugdrug interactions occur if the activity of CYPs are inhibited or induced by another drug. Prescribing multiple drugs to the improve effectiveness of therapy or to treat coexisting diseases is a common practice in clinical medicine. Polypharmacy predisposes patients to adverse effects because of the profound unpredictability in CYP enzymatic-mediated drug metabolism. S-ketamine is a phencyclidine derivative which functions as an antagonist of the N-methyl-Daspartate (NMDA) receptor in the central nervous system. It is a unique anaesthetic producing “dissociative anaesthesia” in high doses and analgesia in low doses. Studies with human liver microsomes suggest that ketamine is metabolized primarily via CYP3A4 and CYP2B6 enzymes. In this thesis, in healthy volunteers, randomized and controlled cross-over studies were conducted to investigate the effects of different CYP inducers and inhibitors on the pharmacokinetics and pharmacodynamics of oral and intravenous S-ketamine. The plasma concentrations of ketamine and its metabolite, norketamine, were determined at different timepoints over a 24 hour period. Other pharmacodynamic variables were examined for 12 hours. Results of these studies showed that the inhibition of the CYP3A4 pathway by clarithromycin or grapefruit juice increased the exposure to oral S-ketamine by 2.6- and 3.0-fold. Unexpectedly, CYP3A4 inhibition by itraconazole caused no significant alterations in the plasma concentrations of oral S-ketamine. CYP3A4 induction by St. John´s wort or rifampicin decreased profoundly the concentrations of oral S-ketamine. However, after rifampicin, there were no significant differences in the plasma concentrations of S-ketamine when it was administered intravenously. This demonstrated that rifampicin inhibited the metabolism of Sketamine at the intestinal level. When CYP2B6 was inhibited by ticlopidine, there was a 2.4- fold increase in the exposure of S-ketamine. These studies demonstrated that low dose oral Sketamine is metabolized both via CYP3A4 and CYP2B6 pathways. The concomitant use of drugs that affect CYP3A4 or CYP2B6, during oral S-ketamine treatment, may cause clinically significant drug-drug interactions.
Resumo:
Wastes and side streams in the mining industry and different anthropogenic wastes often contain valuable metals in such concentrations their recovery may be economically viable. These raw materials are collectively called secondary raw materials. The recovery of metals from these materials is also environmentally favorable, since many of the metals, for example heavy metals, are hazardous to the environment. This has been noticed in legislative bodies, and strict regulations for handling both mining and anthropogenic wastes have been developed, mainly in the last decade. In the mining and metallurgy industry, important secondary raw materials include, for example, steelmaking dusts (recoverable metals e.g. Zn and Mo), zinc plant residues (Ag, Au, Ga, Ge, In) and waste slurry from Bayer process alumina production (Ga, REE, Ti, V). From anthropogenic wastes, waste electrical and electronic equipment (WEEE), among them LCD screens and fluorescent lamps, are clearly the most important from a metals recovery point of view. Metals that are commonly recovered from WEEE include, for example, Ag, Au, Cu, Pd and Pt. In LCD screens indium, and in fluorescent lamps, REEs, are possible target metals. Hydrometallurgical processing routes are highly suitable for the treatment of complex and/or low grade raw materials, as secondary raw materials often are. These solid or liquid raw materials often contain large amounts of base metals, for example. Thus, in order to recover valuable metals, with small concentrations, highly selective separation methods, such as hydrometallurgical routes, are needed. In addition, hydrometallurgical processes are also seen as more environmental friendly, and they have lower energy consumption, when compared to pyrometallurgical processes. In this thesis, solvent extraction and ion exchange are the most important hydrometallurgical separation methods studied. Solvent extraction is a mainstream unit operation in the metallurgical industry for all kinds of metals, but for ion exchange, practical applications are not as widespread. However, ion exchange is known to be particularly suitable for dilute feed solutions and complex separation tasks, which makes it a viable option, especially for processing secondary raw materials. Recovering valuable metals was studied with five different raw materials, which included liquid and solid side streams from metallurgical industries and WEEE. Recovery of high purity (99.7%) In, from LCD screens, was achieved by leaching with H2SO4, extracting In and Sn to D2EHPA, and selectively stripping In to HCl. In was also concentrated in the solvent extraction stage from 44 mg/L to 6.5 g/L. Ge was recovered as a side product from two different base metal process liquors with Nmethylglucamine functional chelating ion exchange resin (IRA-743). Based on equilibrium and dynamic modeling, a mechanism for this moderately complex adsorption process was suggested. Eu and Y were leached with high yields (91 and 83%) by 2 M H2SO4 from a fluorescent lamp precipitate of waste treatment plant. The waste also contained significant amounts of other REEs such as Gd and Tb, but these were not leached with common mineral acids in ambient conditions. Zn was selectively leached over Fe from steelmaking dusts with a controlled acidic leaching method, in which the pH did not go below, but was held close as possible to, 3. Mo was also present in the other studied dust, and was leached with pure water more effectively than with the acidic methods. Good yield and selectivity in the solvent extraction of Zn was achieved by D2EHPA. However, Fe needs to be eliminated in advance, either by the controlled leaching method or, for example, by precipitation. 100% Pure Mo/Cr product was achieved with quaternary ammonium salt (Aliquat 336) directly from the water leachate, without pH adjustment (pH 13.7). A Mo/Cr mixture was also obtained from H2SO4 leachates with hydroxyoxime LIX 84-I and trioctylamine (TOA), but the purities were 70% at most. However with Aliquat 336, again an over 99% pure mixture was obtained. High selectivity for Mo over Cr was not achieved with any of the studied reagents. Ag-NaCl solution was purified from divalent impurity metals by aminomethylphosphonium functional Lewatit TP-260 ion exchange resin. A novel preconditioning method, named controlled partial neutralization, with conjugate bases of weak organic acids, was used to control the pH in the column to avoid capacity losses or precipitations. Counter-current SMB was shown to be a better process configuration than either batch column operation or the cross-current operation conventionally used in the metallurgical industry. The raw materials used in this thesis were also evaluated from an economic point of view, and the precipitate from a waste fluorescent lamp treatment process was clearly shown to be the most promising.
Resumo:
Biocatalysis can be applied in organic synthetic chemistry to counter challenges posed by increased demands towards chemo-, regio- and stereoselectivity, not forgetting the need for greener chemistry. During the last 30 years, biocatalysis with the use of enzymes as chiral catalysts has become more common in chemistry laboratories and industrial processes. In this thesis, the use of lipases as versatile biocatalysts in the acylation of alcohols is examined both in the light of literature examples and four original publications. In the first part of the work presented in this thesis lipases were utilized in two examples concerning secondary alcohols. First, the kinetic resolution of heterocyclic aromatic secondary alcohols through transesterification was thoroughly examined including the studies of competing hydrolysis and esterification reactions. In another example, lipases were utilized in the formation of a dynamic systemic resolution (DSR) process which in turn was used as a developmental tool in the optimization of the dynamic kinetic resolution (DKR) of five heterocyclic aromatic cyanohydrins in one pot for the preparation of cyanohydrin esters as single enantiomers. In the second part of the work, the regio- and stereoselectivity of lipases was used to form sugar conjugates of glyceric and β-amino acids. The primary hydroxyl groups of methyl α-D-galacto-, -gluco- and -mannopyranosides were now acylated trough lipasecatalyzed transesterification and enantioselective lipase-catalyzed ring-opening of β- lactams, respectively.
Resumo:
The starting point of this study is to direct more attention to the teacher and those entrepreneurship education practices taking place in formal school to find out solutions for more effective promotion of entrepreneurship education. For this objective, the strategy-level aims of entrepreneurship education need to be operationalised into measurable and understandable teacher-level practices. Furthermore, to enable the effective development of entrepreneurship education in basic and upper secondary level education, more knowledge is needed of the state of affairs of entrepreneurship education in teaching. The purpose of the study is to increase the level of understanding of teachers’ entrepreneurship education practices, and through this to develop entrepreneurship education. This study builds on the literature on entrepreneurship education and especially those elements referring to the aims, resources, benefits, methods, and practises of entrepreneurship education. The study comprises five articles highlighting teachers’ role in entrepreneurship education. In the first article the concept of entrepreneurship and the teachers role in reflection upon his/hers approaches to entrepreneurship education are considered. The second article provides a detailed analysis of the process of developing a measurement tool to depict the teachers’ activities in entrepreneurship education. The next three articles highlight the teachers’ role in directing the entrepreneurship education in basic and upper secondary level education. Furthermore, they analyse the relationship between the entrepreneurship education practises and the teachers’ background characteristics. The results of the study suggest a wide range of conclusions and implications. First, in spite of many outspoken aims connected to entrepreneurship education, teachers have not set any aims for themselves. Additionally, aims and results seem to mix. However, it is possible to develop teachers’ target orientation by supporting their reflection skills, and through measurement and evaluation increase their understanding of their own practices. Second, applying a participatory action process it is possible to operationalise teachers’entrepreneurship education practices. It is central to include the practitioners’ perspective in the development of measures to make sure that the concepts and aims of entrepreneurship education are understood. Third, teachers’ demographic or tenure-related background characteristics do not affect their entrepreneurship education practices, but their training related to entrepreneurship education, participation in different school-level or regional planning, and their own capabilities support entrepreneurship education. Fourth, a large number of methods are applied to entrepreneurship education, and the most often used methods were different kinds of discussions, which seem to be an easy, low-threshold way for teachers to include entrepreneurship education regularly in their teaching. Field trips to business enterprises or inviting entrepreneurs to present their work in schools are used fairly seldom. Interestingly, visits outside the school are more common than visitors invited to the school. In line, most of the entrepreneurship education practices take place in a classroom. Therefore it seems to be useful to create and encourage teachers towards more in-depth cooperation with companies (e.g. via joint projects) and to network systematically. Finally, there are plenty of resources available for entrepreneurship education, such as ready-made materials, external stakeholders, support organisations, and learning games, but teachers have utilized them only marginally.