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Piezoresistance characterization of silicon nanowires in uniaxial and isostatic pressure variation
Get PDFPublisher's version (útgefin grein)Silicon nanowires (SiNWs) are known to exhibit a large piezoresistance (PZR) effect, making
them suitable for various sensing applications. Here, we report the results of a PZR investigation
on randomly distributed and interconnected vertical silicon nanowire arrays as a pressure sensor.
The samples were produced from p-type (100) Si wafers using a silver catalyzed top-down etching
process. The piezoresistance response of these SiNW arrays was analyzed by measuring their I-V
characteristics under applied uniaxial as well as isostatic pressure. The interconnected SiNWs exhibit
increased mechanical stability in comparison with separated or periodic nanowires. The repeatability
of the fabrication process and statistical distribution of measurements were also tested on several
samples from different batches. A sensing resolution down to roughly 1 mbar pressure was observed
with uniaxial force application, and more than two orders of magnitude resistance variation were
determined for isostatic pressure below atmospheric pressure.Reykjavík UniversityPeer reviewe
A Soft Systems Approach Towards a Theory of Knowledge Worker Productivity
Get PDFThe main purpose of this research is to contribute towards a theory of knowledge
worker productivity (KWP). When it comes to KWP there is no single integrated body
of knowledge which can be used for analytical and empirical testing and applied to
real world problems. Knowledge and research relevant to KWP is distributed through
multiple fields of study and at a high level of detail. This research attempts to explore
KWP holistically from an industrial engineering standpoint, by looking at the systems
involved. It utilizes the first three activities in the soft systems methodology (SSM) to
explore the problem situation, formulate a purposeful activity model for the individual
knowledge worker (KW) and debate the situation using the results of multiple literature
reviews. The findings are then used to propose a draft of a holistic framework of KWP
relevant to individual KWs and their work. It consists of three papers: (I) A Soft Systems
Approach to KWP - Analysis of the Problem Situation, (II) A Soft Systems Approach to
KWP:a Purposeful Activity Model for the Individual and (III) Towards a Holistic KWP
framework. To develop a holistic framework of KWP, the interpretations and inferences
made cumulatively throughout the journey from the literature reviews and the results of
the SSM activities were abstracted into main components and their influencing factors.
The main components of the conceptual framework are the state of the individual KW,
work done and outcome. Outcome of relevant work can be value for the individual
KW, others in the social system and the organization. It is human nature to gravitate
towards creating value for oneself, therefore, the organization needs to align their needs
with what creates value for the individual KW to maximize value contribution towards
their organizational goals and objectives. This can be done by influencing the state of
the individual KW, through external factors such as reward systems, culture, support,
and relationships, to guide the KW towards engaging in preferred behaviors such as
organizational citizenship behavior. There are also internal factors that affect the state of
the KW, which are influenced by the KW’s actions, traits, worldview, and interpretation
of his environment and experiences. The state of the individual KW affects the KW’s
intuition when evaluating work and making decisions in his process of getting things
done. This study adds to the literature by giving an overview of the many elements
that affect the productivity of the individual KW, abstracting them into key insights and
drawing up a simplified and concise conceptual framework. This study also uses a new
approach to SSM by adapting it to use inferences made from literature reviews rather
than using interviews and discussions with stakeholders.Tilgangur þessarar rannsóknar er að byggja upp kenningu um framleiðni þekkingarstarfsmanna. Þegar það kemur að framleiðni þekkingarstarfsmanna þá er ekki til einn
þekkingargrunnur sem er samþættaður. Þekkingargrunnur sem hægt er að hagnýta.
Þekking um framleiðni þekkingarstarfsmanna er dreifð yfir mörg rannsóknarsvið og er
í miklum smáatriðum. Þessi rannsókn stefnir á að skoða framleiðni þekkingarstarfsmanna á heildrænan hátt með verkfræðilegri nálgun, með því að skoða kerfin sem
tengjast þekkingarstarfsmönnum. Rannsóknin notar fyrstu þrjár athafnirnar í mjúkri
kerfisnálgun (Soft Systems Methodology) til að skoða vandamálið hvernig á að stýra
og bæta framleiðni þekkingarstarfsmanna með því að rýna í ritrýndar greinar á kerfisbundinn hátt. Fyrstu þrjár athafnirnar í mjúkri kerfisnálgun eru: (1) leita upplýsinga
um vandasamt ástand, (2) búa til viðeigandi líkön af markvissum athöfnum (Purposeful
Activity Models), og (3) ræða um ástand út frá líkönum. Niðurstöður rannsóknarinnar
eru svo notaðar til að leggja fram tillögu af heildrænum ramma um framleiðni þekkingarstarfsmanna. Rannsóknin samanstendur af þremur greinum: (I) A Soft Systems
Approach to KWP - Analysis of the Problem Situation, (II) A Soft Systems Approach to
KWP:a Purposeful Activity Model for the Individual og (III) Towards a Holistic KWP
framework. Til þess að þróa heildrænan ramma um framleiðni þekkingarstarfsmanna,
voru ályktanir dregnar úr þeim ritrýndu greinum sem teknar voru fyrir og niðurstöður
athafnanna í mjúkri kerfisnálgun túlkaðar til þess að greina aðalatriðin og þá þætti sem
hafa áhrif á þau. Aðalatriðin sem mynda huglæga ramann er ástand einstaklingsins,
vinna og útkoma. Útkoman af viðeigandi vinnu getur verið virði fyrir einstaklinginn,
aðra í félagslegu kerfi hans og skipulagsheildin. Það er mannlegt eðli að hallast að því
að búa til virði fyrir sjálfan sig, þess vegna þarf skipulagsheildin að samræma þeirra
þarfir við það sem býr til virði fyrir einstaklinginn til að hámarka framlag þeirra til
skipulagsheildarinnar. Þetta er hægt með því að hafa áhrif á ástand einstaklingsins í
gegnum ytri þætti eins og verðlaunakerfi, menningu, stuðning og sambönd til þess að
beina þekkingarstarfsmanninum í áttina að æskilegri hegðun. Það eru einnig innri þættir
sem hafa áhrif á ástand þekkingarstarfsmannsins svo sem hegðun þeirra, eiginleikar,
heimsmynd og túlkun á umhverfinu og upplifunum. Ástand einstaklingsins hefur áhrif
á innsæi hans þegar hann er að meta vinnu sína og taka ákvarðanir í ferlinu að koma
hlutum í verk. Þessi rannsókn auðgar þekkingu á framleiðni þekkingarstarfsmanna með
því að gefa yfirsýn yfir þá ótal þætti sem hafa áhrif á framleiðni einstaklingsins og draga
þá saman í einfalt og hnitmiðaðan huglægan ramma. Þessi rannsókn notar einnig nýja
nálgun á mjúkri kerfisnálgun með því að aðlaga það til að nota ályktanir dregnar úr
ritrýndum greinum frekar en að nota viðtöl og umræður við hagsmunaaðila
The capability of recurrent neural networks to predict turbulence flow via spatiotemporal features
Get PDFThis study presents a deep learning (DL) neural network hybrid data-driven method that is able to predict turbulence flow velocity field. Recently many studies have reported the application of recurrent neural network (RNN) methods, particularly the Long short-term memory (LSTM) for sequential data. The airflow around the objects and wind speed are the most presented with different hybrid architecture. In some of them, the data series is used with the known equation, and the data is firstly generated. Data series extracted from Computational Fluid Dynamics (CFD) have been used in many cases. This work aimed to determine a method with raw data that could be measured with devices in the airflow, wind tunnel, water flow in the river, wind speed and industry application to process in the DL model and predict the next time steps. This method suggests spatialtemporal data in time series, which matches the Lagrangian framework in fluid dynamics. Gated Recurrent Unit (GRU), the next generation of LSTM, has been employed to create a DL model and forecasting. Time series data source is from turbulence flow has been generated in a laboratory and extracted via 2D Lagrangian Particle Tracking (LPT). This data has been used for the training model and to validate the prediction in the suggested approach. The achievement via this method dictates a significant result and could be developed.This work was performed in the Center of Excellence (CoE) Research on AI and Simulation Based Engineering at Exascale (RAISE) and the EuroCC projects receiving funding from EU’s Horizon 2020 Research and Innovation Framework Programme under the grant agreement no.951733 and no. 951740 respectively.Peer Reviewe
Biomarkers in cerebrospinal fluid of neonates at risk of brain injury. Association with death and disability
Get PDFBakgrunnur
Ágrip
Börn sem verða fyrir súrefnisskorti í fæðingu og börn sem fæðast fyrir fulla meðgöngu eiga á hættu að lifa ekki af eða hljóta varanlegan heilaskaða. Hættan á þessum fylgikvillum hefur ekki minnkað á síðustu áratugum þrátt fyrir miklar læknisfræðilegar framfarir. Súrefnisskortur í fæðingu og önnur áföll setja í gang efnaferla í heilanum sem leiða til truflunar á starfsemi taugafruma og jafnvel taugafrumudauða. Sýkingar eru algengur fylgikvilli þess að fæðast fyrir tímann og eru ein helsta orsök hárrar dánartíðni fyrirbura á nýburaskeiði. Þær tengjast einnig truflunum í öndun og blóðrás vegna áhrifa bólguefna á stjórnstöð í heilastofni. Bólguferli gegna lykilhlutverki sem orsakavaldur heilaskaða bæði eftir sýkingar og við súrefnisþurrð. Mikilvægt er að hafa í huga að óþroskaður heili nýbura, einkum fyrirbura, er viðkvæmur fyrir alls kyns áreiti á nýburaskeiði. Truflun á þroska heilans, jafnvel án sjáanlegs meins í heilavef, getur valdið því að barnið hljóti varanlegar fatlanir. Mögulegt er að mæla í lífsýnum efni svo sem bólguefni og prótein sem tengjast hinum flóknu efnaferlum heilaskaðans og/eða heilaþroskans.
Markmið og tilgátur
Markmið þessa verkefnis var að finna leiðir til að greina heilaskaða og meta áhættu á taugaþroskaröskun hjá nýburum. Til að ná þeim markmiðum vildum við finna lífefni í mænuvökva sem mundu geta: i) gefið upplýsingar um útbreiðslu og alvarleika heilaskaða hjá fullburða börnum sem fengið höfðu súrefnisskort í fæðingu sem og horfur þessara barna, ii) spáð fyrir um framtíðarhorfur hjá fyrirburum, og iii) útskýrt truflanir á hjartslætti og öndun hjá nýburum með sýkingar.
Megintilgátur okkar voru í fyrsta lagi, að magn bólguefna i) mundi mælast hækkað í mænuvökva hjá börnum sem lent höfðu í súrefnisskorti í fæðingu og tengdust bæði meiri alvarleika skaðans og verri horfum, ii) að þau væru hærri hjá fyrirburum í samanburði við fullburða börn sem ekki höfðu hlotið súrefnisskort í fæðingu, og að iii) hækkun á bólguefninu Prostaglandin E2 (PGE2) mundi tengjast, ekki einungis súrefnisskorti í fæðingu, heldur einnig truflunum í öndun og hjartslætti hjá sýktum nýburum.
Í öðru lagi að önnur lífefni, sem sérstaklega tengjast hinum ýmsu efnaferlum heilaskaða hjá nýburum, væru hækkuð í mænuvökva hjá þeim
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börnum sem orðið höfðu fyrir súrefnisskorti í fæðingu og að þau tengdust alvarleika skaðans og horfum barnanna.
Í þriðja lagi að próteinmynstur í mænuvökva væri mismunandi hjá fyrirburum annars vegar og fullburða börnum hins vegar og að magn próteina sem tengjast hinum ýmsu efnaferlum í heilaþroskanum hefðu forspárgildi um taugaþroskaraskanir hjá fyrirburum.
Aðferðir
Til að kanna tilgátur okkar mældum við lífefni í mænuvökva fullburða barna sem orðið höfðu fyrir súrefnisskorti í fæðingu, hjá fyrirburum með eða án sýkingar og hjá fullburða börnum í viðmiðunarhópi.
Fullburða börn sem voru innlögð á nýburagjörgæsludeild Karolinska sjúkrahússins í Stockholm á tímabilinu 2000 til 2004 vegna fósturköfnunar voru höfð í rannsóknum I, III og IV. Öll börnin uppfylltu skilyrði fyrir heilakvilla af völdum súrefnisskorts í fæðingu og var mænuástunga gerð sem liður í almennri uppvinnslu. Viðmiðunarhópur var börn, einnig fædd eftir fulla meðgöngu, sem voru inniliggjandi á Karolinska sjúkrahúsinu vegna gruns um sýkingu en höfðu ekki lent í súrefnisskorti í fæðingu og voru ekki með heilakvilla. Fyrirburar innlagðir á Karolinska sjúkrahúsið á árunum 2002 til 2004 sem voru mænustungnir vegna gruns um sýkingu voru í rannsóknum II og V. Fullburða börn sem lágu á sama tíma á Karolinska sjúkrahúsinu og voru einnig mænustungin vegna gruns um sýkingu voru viðmiðunarhópur.
Mænuvökvi frá þessum börnum var rannsakaður með ELISA aðferð. Magn PGE2 og PGE2 myndefnis (PGEM) var mælt í rannsókn I og II og magn interleukin 6 (IL-6) og fas-ligand (FasL) í rannsókn III. Prótein-svipgerð í mænuvökva í rannsóknum IV og V var mæld með tækni sem mælir mörg prótein samtímis og byggir á sækni próteina í fyrirfram gerða mótefnalausn. Mótefnalausnin var gerð úr próteinögnum sem valdar voru úr próteingagnabanka. Magn 178 próteina var mælt í sýnunum.
Öllum börnum var fylgt eftir til 18-24 mánaða aldurs.
Niðurstöður
Helstu niðurstöður okkar voru, í fyrsta lagi, að magn bólguefna eykst í mænuvökva, bæði við blóðsýkingar og fósturköfnun, og hafa notagildi við greiningu á sjúkdómsástandi og forspárgildi um horfur sjúklinga. Í öðru lagi, að ýmis prótein sem tengjast efnaferlum í meingerð heilaskaða af völdum súrefnisskorts safnast upp í mænuvökva eftir fósturköfnun. Aukið magn þessara próteina tengist verri heilaskaða og magn þeirra í mænuvökva hafði tengsl við framtíðarhorfur barnanna. Í þriðja lagi sýndum við að prótein- svipgerð í mænuvökva er ekki eins hjá fyrirburum og hjá fullburða börnum.
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Einnig sáum við að hjá fyrirburum sem greindust með taugaþroskaraskanir fyrir tveggja ára aldur var skortur á ýmsum próteinum sem taka þátt í þroska heilans.
Í rannsóknum I og II mældust bólguefnið PGE2 og afleiða þess PGEM hækkuð í mænuvökva. Hjá börnum með sýkingar (rannsókn II) höfðu þessi lífefni notagildi sem greiningartæki snemma í sjúkdómsferlinu og tengdust truflun á hjartslætti og öndunarstarfsemi. Hjá börnum með heilakvilla eftir fósturköfnun (rannsókn I) voru tengsl á milli magns þessara lífefna og alvarleika heilaskaðans, bæði gráðu heilakvilla og horfur barnanna. IL-6 er annað bólguefni sem mældist í auknu magni í mænuvökva þeirra barna sem urðu fyrir súrefnisskort í fæðingu og tengdist það verri heilaskaða (rannsókn III). Í þeirri rannsókn voru einnig tengsl á milli magns FasL og alvarleika heilaskaða en það er lífefni sem tekur þátt í dauða taugafruma í flókinni meingerð heilaskaða eftir súrefnisskort. IL-6 og FasL notuð saman spáðu fyrir um alvarleika heilaskaðans, gráðu heilakvilla og horfur, með miklu næmi og sértæki. Próteinmynstur í mænuvökva barna með heilakvilla eftir fósturköfnun (rannsókn IV) einkenndist af bólguferlum og öðrum próteinum sem tengjast efnaferlum heilaskaða af völdum súrefnisskorts. Hækkað magn þessara próteina tengdist meiri einkennum um heilakvilla og verri langtímahorfum þessara barna. Próteinmynstur í mænuvökva fyrirbura var öðruvísi en hjá fullburða börnum (rannsókn V), og var þar sérstaklega áberandi hækkun á bólgupróteinum hjá fyrirburum. Í þeirri rannsókn var magn próteina sem tengdust heilaþroskanum minna í mænuvökva þeirra fyrirbura sem greindust með óeðlilegan taugaþroska við 18-24 mánaða leiðréttan aldur en hjá fyrirburum sem voru með eðlilegan taugaþroska.
Ályktun
Útfrá þessum niðurstöðum ályktum við að ýmis bólguefni og önnur lífefni í mænuvökva geta verið gagnleg við mat á ástandi og horfum nýbura sem eru í hættu á heilaskaða eða taugaþroskaröskun. Þau geta verið gagnleg i) við greiningu á heilakvilla af völdum súrefniskorts í fæðingu, ii) við greiningar á sýkingum ii) við mat á alvarleika heilaskaða hjá nýburum sem hlotið hafa fósturköfnun og við mat á þörfinni fyrir meðferð og iii) við mat á framtíðarhorfum fyrirbura, og fullburða barna með heilakvilla.
Að auki gefa þessar niðurstöður mikilvægar upplýsingar um meingerð heilaskaðans, sem gætu nýst við þróun á nýjum meðferðarúrræðum.Background
Prematurity with its complications and hypoxic-ischemic encephalopathy (HIE) following birth asphyxia in full-term infants are the most important contributors to a high incidence of early neonatal mortality and lifelong neurodevelopmental disabilities originating in the neonatal period. Devastating long-term outcomes have not decreased markedly within the last decades despite extensive medical advances. Various injurious processes are stimulated by external insult and can lead to brain cell damage. This includes inflammatory processes, which are important contributors to brain injury in both sepsis and hypoxia-ischemia. Sepsis is a common complication of prematurity and the most frequent cause of mortality in the neonatal period. It is associated with cardiorespiratory disturbances, as a result of a disrupted autonomic control in the brain stem. It is important to bear in mind the vulnerability of the developing brain, especially of the preterm infant. Diverse postnatal events may alter normal brain development and lead to an adverse neurodevelopmental outcome, even without apparent lesion in the brain tissue. Measuring biomarkers in body fluids that correlate with the processes of brain injury and/or brain development is feasible.
Aims
The focus of this thesis was to diagnose perinatal brain injury and identify infants at risk of adverse neurodevelopmental outcomes. Specifically, the aim was to discover biomarkers in cerebrospinal fluid (CSF) that would: i) identify the degree of HIE and the clinical outcome following perinatal asphyxia, ii) predict the neurodevelopmental outcome of preterm infants, and iii) correlate with the onset of neonatal sepsis and cardiorespiratory disturbances.
We first hypothesized that neuroinflammation would be observed following birth asphyxia and that inflammatory mediators could serve as biomarkers of the degree of HIE and the clinical outcome of the patients. Furthermore, the inflammatory mediator prostaglandin E2 (PGE2) would correlate with the consequences of perinatal asphyxia and early neonatal sepsis and autonomic dysfunction. Secondly, the levels of brain-specific proteins, including apoptotic markers, cell structural proteins, and synaptic proteins, in CSF, could serve as diagnostic and prognostic biomarkers in HIE. Thirdly, the proteome in preterm infants would differ from that in term-born infants and a specific protein signature would predict adverse neurodevelopmental outcomes in the preterm infants.
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Methods
We analyzed CSF of term infants with HIE, infected and noninfected preterm infants, and term control infants to test these hypotheses. Term infants who were cared for at the neonatal intensive care unit at the Karolinska Hospital in Stockholm due to perinatal asphyxia, between 2000 and 2004, were enrolled prospectively into studies I, III, and IV. Included infants all fulfilled the criteria of perinatal asphyxia and had a lumbar puncture performed on clinical indications. Term infants without asphyxia or any other pathology in the brain who were cared for at the Karolinska Hospital at the same time for suspected infection served as controls. Preterm infants cared for at the neonatal intensive care unit at Karolinska Hospital between 2002 and 2004 and who underwent clinically indicated lumbar puncture were prospectively enrolled into studies II and V. Term infants with suspected infection served as controls.
CSF was analyzed from patients and controls. ELISA technique was utilized to measure PGE2 and prostaglandin E2 metabolite (PGEM) in studies I and III and for measuring interleukin 6 (IL-6) and fas-ligand (FasL) in study III. In studies IV and V, proteomic profiling was performed utilizing an antibody affinity-based proteomic array. We measured the relative abundances of 178 unique proteins. The antibodies for the suspension bead array were produced from protein fragments chosen from a protein database for the analysis.
Neurological follow-up was performed at 18-24 months in all infants.
Results
Our main findings were, firstly, that inflammatory biomarkers were increased in CSF in response to both asphyxia and sepsis and had diagnostic as well as prognostic value. Secondly, unique brain-specific proteins were increased in CSF of asphyxiated infants and correlated with the extent of brain injury and clinical outcome. Thirdly, decreased levels of neurodevelopmentally related proteins correlated with unfavorable neurodevelopmental outcomes of preterm infants.
More specifically, the inflammatory mediators PGE2 and its more stable metabolite PGEM were found in increased amounts in studies I and II. They had diagnostic value in sepsis and correlated with cardiorespiratory disturbances (study II). In infants who had suffered perinatal asphyxia, they correlated with the HIE degree and the outcome of patients (study I). IL-6 is another inflammatory mediator, that was found in an increased amount in asphyxiated infants in study III and correlated with HIE degree and clinical outcome. In that study, FasL, which is an apoptotic marker and associated
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with brain cell death in hypoxic-ischemic (HI) brain injury, was found to increase as well and predicted the extent of brain injury and clinical outcome. IL-6 and FasL together predicted HIE degree and outcome with high sensitivity and specificity. Protein profiles in study IV revealed an upregulation of inflammatory pathways as well as other pathways involved in HI brain injury. Several proteins predicted the HIE degree and the clinical outcome of the infants. In study V preterm infants had a different protein profile than term-born infants. Furthermore, depressed levels of several neurodevelopmentally related proteins correlated with adverse outcomes in the preterm group.
Conclusion
From these results, it may be concluded that several inflammatory- as well as structural and functional brain-specific biomarkers could serve as diagnostic tools in infants at risk of brain injury. Specifically, they could; i) have diagnostic value in HIE and sepsis, ii) help identify infants with HIE grade II and III, who would benefit from neuroprotective treatment after perinatal asphyxia, and iii) have value in predicting the risk of adverse neurological outcomes in infants with HIE and preterm infants.
Furthermore, they reflect the injurious processes in HIE and expand the knowledge of the neurodevelopmental processes in the developing brain. This might be important for the invention of future neuroprotective methods
Evolution of reproductive isolation in sympatric Arctic charr morphs (Salvelinus alpinus)
Get PDFThe theory of divergence by trophic polymorphism, an important part of diversification in
vertebrates, has recently been extended to encompass the interplay of developmental,
ecological and evolutionary processes (Eco-Evo-Devo dynamics). However, this extended
theory doesn’t thoroughly explain the evolution of reproductive isolation, which is
unfortunate considering the recent advances from the field of speciation. In this thesis, I
argue that the Arctic charr morphs of Thingvallavatn are an ideal system to study how
reproductive isolation is embedded within the theory of divergence by resource
polymorphism, which I present through five papers. First, I focused on two sympatric
morphs, the small-benthic (SB) and the planktivorous (PL) charr. Common-garden
experiments showed limited evidence for hybridization to affect the structure of trait
covariance in both morphs, regarding morphology, developmental timing and feeding
behaviour (Paper I), and personality traits (Paper II). However, information on gene
expression variability in embryos indicated that hybridization might influence evolvability
(Paper III). Multiple reproductive barriers between the two morphs, involving habitat use,
assortative mating and hybrid development were also assessed (Paper IV). Finally, Paper V
combines field studies and rearing experiments to explore the interplay between habitat
choice and offspring development in the large-benthic (LB) charr, which spawns earlier in
the season than the other morphs. The results suggested that LB-charr favour temperature
conditions that may delay offspring development. Altogether, these findings provide an
overview on reproductive isolation among the Arctic charr morphs of Thingvallavatn and
constitute a primer to study speciation in an Eco-Evo-Devo context
Mechanism of Interlayer Transport on a Growing Au(111) Surface: 2D vs. 3D Growth
Get PDFThe atomic scale transitions corresponding to diffusion and interlayer transport of a Au adatom on the low energy, close packed Au(111) surface are studied using density functional theory calculations within the generalized gradient approximation. Minimum energy paths and estimates of activation energy are calculated for processes that influence whether the crystal grows layer-by-layer, i.e. 2D growth, or whether new islands tend to nucleate on top of existing islands resulting in 3D growth. Kinks on island edges turn out to provide paths for adatom descent with lower activation energy than straight steps. The energy barrier for an adatom to round the corner and enter a kink site is significantly higher. A descent mechanism that places an adatom near but not at a kink site can therefore promote the formation of a new row of step atoms and lead to the introduction of additional kink sites, thereby opening up new low activation energy paths for descent and promotion of 2D growth. The sites adjacent and above the step edge provide large binding energy for the adatom, especially at the B-type step, and form a trough along which the adatom can migrate before descending, thereby increasing the probability that an adatom finds a kink on the B-type step. These features of the energy landscape representing the interaction of a Au adatom with the surface point to the possibility of a re-entrant layer-by-layer growth mode of the low energy, close packed surface of the gold crystal.This work was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska Curie Innovative Training Network ELENA and by the Icelandic Science Fund
Hydrologic Performance of Sustainable Urban Drainage Systems in Cold Maritime Climates
Get PDFSustainable urban drainage systems (SUDS) are increasingly implemented to mitigate flood risk and augment environmental quality and wellbeing in cities. Vegetated swales are one of the most common SUDS components, yet they are among the least studied in cold climates. The goal of this research was to assess the performance of a grass swale in a cold maritime climate characterized by frequent freezing and thawing, rain-on-snow events, and repeated midwinter snowmelt. Synthetic runoff experiments, single-ring infiltration measurements, and continuous monitoring of soil and meteorological conditions were undertaken over two years in the BREEAM-certified neighborhood of Urriðaholt, Iceland. The grass swale infiltrated water during all seasons but at a lower rate in winter. Sparsely vegetated and barren areas were more susceptible to concrete frost formation and heave than well vegetated areas during repeated freeze-thaw. The dense vegetation in the grass swales and the intertwined root system aided the hydrological performance of the grass swale by enhancing the near-surface soil porosity while providing soil binding that resists structural deformation. Soil frost modeling indicated that while soil frost has decreased in the last 70 years, the freezing season shifted towards midwinter to coincide with the largest rain-on-snow events. This, combined with increasing rain-on-snow volume, suggests that the risk of urban flooding during winter may increase in the next decades with climate warming. Greenifying urban areas is essential to improve resilience and mitigate the adverse impacts of climate change.Blágrænar ofanvatnslausnir (BGO) eru í auknum mæli innleiddar til þess að draga úr flóðahættu, auka umhverfisgæði og vellíðan í borg. Gróðurrásir eru algeng útfærsla á BGO, en minnst kannaðar í köldu loftlagi. Markmið þessarar rannsóknar var að meta virkni gróðurrásar í köldu sjávarloftslagi, sem einkennist af tíðum umhleypingum frost og þíðu, regn-á snjó atburðum og snjóbráð á miðjum vetri. Framkvæmdar voru afrennslistilraunir, ísigsmælingar, og samfelldar mælingar á jarðvegi og veðurfari yfir tveggja ára tímabil í umhverfisvottaða hverfinu Urriðaholti, í Garðabæ. Gróðurrásin miðlaði vatni í jarðveg á öllum árstíðum, en þó með lægri skilvirkni vegna frostmyndunar að vetri. Strjál og gróðurlaus svæði voru næmari fyrir hýfingu og myndun steypufrosts í kjölfar endurtekinna frost-þíðu kafla en gras. Þétt blöð og samofið rótarkerfi grass hjálpuðu að viðhalda vatnafræðilegri virkni, með því að auka gleypni yfirborðs og binda jarðveg svo hann aflagist ekki. Hermanir á jarðvegshita gáfu til kynna að dregið hafi úr frosti á síðustu 70 árum, að frosttímabilið hafi styst í átt að mánuðum þar sem mesta rigning mælist á snjó. Þessi þróun samhliða meiri úrkomu á snjó gefur vísbendingu um að hætta á ofanflóðum í þéttbýli geti aukist á næstu áratugum með hlýnandi loftslagi. Að viðhalda grænum svæðum í borg er nauðsyneg til að auka viðnámsþol og draga úr neikvæðum áhrifum hnattrænar hlýnunar
Partnership in the Third Space: Creating a new learning arena in Icelandic preschool teacher education
Get PDFThe project is an empirical qualitative research that aims to explore the concept of the “third space” as a collaborative learning arena with partners in Icelandic preschool teacher education. The explicit focus is preschool teacher education, specifically the connection between theory and practice during field practice and how the third space can be used to link theory and practice. The overall research question is: “How can ‘the Third Space’ become a meaningful learning arena in Icelandic teacher education?” Thus, emphasis was on the issues of importance in developing the third space—that is, partnership in preschool teacher education, preschool student teachers’ learning during their field practice, and communication and division of labor among actors. To achieve this goal, four studies were conducted, presented in four articles: Article I, Historical perspective of the third space in Icelandic preschool teacher education; Article II, University-preschool collaboration in preschool student teacher education in Iceland; Article III, Between a rock and a hard place: The importance of education and professional development of preschool student teachers in field practice; and Article IV, During the field practice, their professionalism increases: Collaboration in the practicum.
The contribution of the project is threefold. First, the project is intended to contribute to the theoretical knowledge regarding third space and partnership in preschool teacher education, an issue that has not been at the forefront in preschool teacher education studies. Second, as the context of the project is Iceland, it contributes to the Icelandic and international discourse on preschool teacher education and policy. The dissertation explores partnership in preschool teacher education and how stakeholders perceive the collaboration. The four studies contribute to knowledge about the university-preschool partnership and how it affects student teachers’ learning. Third, the intention of the project is to contribute to professionalism in preschool teacher education.
Sociocultural constructivism is the epistemological framework for this project. In cultural and social contexts, by interacting, asking questions, and discussing issues with each other, individuals construct meanings of situations (Creswell, 2009; Crotty, 1998; Edwards, 2005). The project is framed by Engeström’s theory of expansive learning (2015) and theory about the third space (Bhabha, 1990; Zeichner, 2010) and partnership (Halvorsen, 2014; Smith, 2016).
The methodology is qualitative research (Creswell & Poth, 2018) using triangulated data collection. To get an in-depth understanding of the issue and to ensure triangulation, data were collected from different sources, in three different ways using multiple theories in data analysis (Merriam & Tisdell, 2016).
The findings from the four studies provide an answer to the overall question” “How can ‘the Third Space’ become a meaningful learning arena in preschool teacher education?” The findings indicate that true partnership in the preschool teacher education in Iceland is scarce, and that the partnership is more separated than collaborative. The main findings show that participants found it important to build good partnerships, involve more stakeholders, and strengthen the collaboration between the field and the universities, with the overall goal of ensuring professionalism in the early childhood sector. They saw this as an important factor in creating a shared learning platform that held innovation, vitality, and flexibility—all fundamental steps to forming true partnership. Participants also discussed that lack of communication and discussions seemed to hinder the collaboration and decreases opportunities to develop true partnership
The relationship between international and national law: re-visiting concepts of dualism and monism
Get PDFThe relationship between international and national law is increasingly being tested by jurisdictions and decisions of international courts. International courts have multiplied in the last two decades and have become permanent and active participants in the international arena. States and international organizations have considered the establishment and jurisdiction of such dispute settlement bodies vital for the enforcement of international law obligations of both states and individuals. States have undertaken an international obligation to comply with decisions of international courts. Particularly, in light of the enhanced role of international courts with respect to the enforcement of human rights and individual criminal responsibility, their jurisdiction and decisions have required major implementation at the national level. The authority of international courts calls for a theoretical understanding of the relations between international and national law. In only a short time, their authority has put into the spotlight fundamental principles of international law, such as human rights, criminal responsibility of individuals for international crimes, states’ responsibility, enforcement by international actors, and remedies. These areas of law are inter-dependent, both in substance and space. International human rights and individual criminal responsibility for serious crimes are matters of international law, undertaken and enforced at the international level, but to be realized at the national level. At both levels, every day practice illustrates the dire need of a theoretical understanding of the multilayered situation. Conventional application of established legal doctrines has often proved to be conflicting and unsatisfactory. Facing the dilemma, a grander strategy is needed. This thesis presents a study on this new phenomenon from a variety of perspectives. The six publications included study international legal norms that seek to activate domestic legal system, enforcement of international courts, and implementation at the national level (in particular in the Nordic countries). These studies are mainly in the area of international human rights, international humanitarian law, and international criminal law. The summary places the published text in a theoretical, historical and analytical context. The primary theoretical foundation of the relations between international and national law are the theories of dualism and monism. While set out in the nineteenth century, the theories have remained the main foundation for the kinship. The summary revisits and tests the components of these theories in light of the case studies. It concludes that the reliance of the theories is problematic, as their key foundations do not hold. This situation has real-world ramifications as actors with major interests at hand, primarily individuals, find themselves at times trapped, and left with a false promise of law.Kansainvälisten tuomioistuinten toimivalta ja päätökset koettelevat yhä enenevässä määrin kansainvälisen ja kansallisen oikeuden rajoja. Kansainvälisten tuomioistuinten määrä on moninkertaistunut viime vuosikymmenten aikana, ja niistä on tullut yhä pysyvämpiä ja aktiivisempia toimijoita kansainvälisellä areenalla. Valtiot ja kansainväliset järjestöt ovat katsoneet, että tällaiset tuomioistuimet ovat elintärkeitä valtioiden ja yksilöiden kansainvälisoikeudellisten oikeuksien ja velvollisuuksien toteutumisen kannalta. Useimmat valtiot ovat myös antaneet suostumuksensa noudattaa tuomioistuinten päätöksiä. Etenkin ihmisoikeustuomioistuinten ja kansainvälisten rikostuomioistuinten päätösten toimeenpaneminen on usein vaatinut merkittäviä uudistuksia kansallisella tasolla. Kansainvälisten tuomioistuinten toimivallan ymmärtäminen vaatii kansallisen ja kansainvälisen oikeuden välisten suhteiden teorioimista. Tämä toimivalta on lyhyessä ajassa asettanut valokeilaan kansainvälisen oikeuden perustavanlaatuisia periaatteita ja kysymyksiä, kuten ihmisoikeudet, yksilön rikosvastuun kansainvälisistä rikoksista, valtiovastuun, kansainvälisten toimijoiden toimeenpanovallan ja oikeussuojakeinot. Nämä oikeudelliset kysymykset ovat toisiinsa liitoksissa niin substanssin puolesta kuin tilallisestikin. Ihmisoikeudet ja yksilön rikosvastuu kansainvälisistä rikoksista ovat kansainvälisoikeudellisia kysymyksiä, joista päätetään kansainvälisellä tasolla, mutta ne toimeenpannaan kansallisella tasolla. Päivittäiset käytännöt molemmilla tasoilla osoittavat tarpeen tämän monikerroksisen tilanteen teoreettiselle ymmärtämiselle. Olemassa olevien oikeudellisten doktriinien perinteinen soveltaminen on usein osoittautunut ristiriitaiseksi ja epätyydyttäväksi. Ongelmaan vastaaminen vaatii laajempaa strategiaa. Väitöskirjassa tarkastellaan tätä ilmiötä useasta näkökulmasta. Väitöskirjan ytimen muodostavissa kuudessa artikkelissa tutkitaan kansainvälisiä oikeussääntöjä, jotka pyrkivät toimimaan kansallisen oikeusjärjestelmän kautta, kansainvälisten tuomioistuinten toimeenpanovaltaa, ja niiden päätösten implementoimista kansallisella tasolla (etenkin Pohjoismaissa). Artikkelien tapaustutkimukset koskevat pääosin ihmisoikeuksia, humanitaarista oikeutta ja kansainvälistä rikosoikeutta. Väitöskirjan johtopäätösluku asettaa näiden tutkimusten tulokset teoreettiseen, historialliseen ja analyyttiseen kontekstiin. Kansainvälisen ja kansallisen oikeuden suhteiden teoreettisen perustan muodostavat dualismi ja monismi. Vaikka ne on luotu 1800-luvulla, nämä teoriat ovat säilyttäneet asemansa oikeusteoriassa. Väitöskirjan johtopäätösluvussa tutkitaan ja testataan näiden teorioiden eri osia väitöskirjan tapaustutkimusten valossa. Väitöskirjassa tullaan siihen tulokseen, että näihin teorioihin tukeutuminen on ongelmallista, koska niiden perusta ei enää ole vakaa. Tällä on käytännön vaikutuksia, sillä toimijat, ennen kaikkea yksilöt, joiden intressit ovat vaakalaudalla, jäävät usein vangiksi oikeuden valheellisten lupausten väliin
Stabilization and solubilization of difluprednate in aqueous cyclodextrin solution and its characterization for ophthalmic delivery
Get PDFPublisher´s version / Útgefin greinDifluprednate is a synthetic glucocorticoid used for the treatment of postoperative inflammation and pain
associated with endogenous uveitis. It is very lipophilic with limited aqueous solubility and stability. The only
available marketed formulation is an oil-in-water ophthalmic emulsion that has many drawbacks. Cyclodextrin
(CD) molecules are widely used to increase the solubility and stability of hydrophobic drugs through the for-
mation of drug/CD complexes. This study aims to investigate degradation kinetics, stability and solubility of
difluprednate in aqueous CD solutions in an effort to develop aqueous eye drop vehicle for ophthalmic delivery.
Phase-solubility and kinetics studies were performed in presence of different CDs and polymers. Characterization
of the drug/CD complexes was done using techniques like NMR, DSC, and FTIR. The results show that diflu-
prednate has maximum stability at pH 5 in aqueous CD solution. HPγCD was found to be the best solubilizer and
stabilizer among all the CDs tested. The stability was further improved with the combination of HPγCD and
different polymers. Characterization of the difluprednate/HPγCD complex in solid and solution state confirmed
the presence of a drug/CD complex. It was possible to solubilize 0.1% difluprednate using HPγCD and stabilize
the drug using combination of CD and polymer in aqueous solutionThis work was financially supported by the European Union grant
no. MSCA-ITN-2017-765441 (transMed) and the Faculty of Pharmaceutical Sciences, University of Iceland.Peer-Reviewe