Whispering gallery resonances in dielectric disk

Dielectric nanostructures, such as spherical nanoimprints, have emerged as a promising alternative for efficiency enhancement by light-trapping in thin solar cells. Some of the effectivity increase can be explained by resonant modes called Whispering gallery modes. The rationale of this increase is not fully understood and the hypothesis is that nanostructure parameters and coupled modes can be directly related to the absorption resonance. In order to study Whispering gallery modes and coupled modes in nanostructures in addition to the parameters of the nanostructures, a numerical algorithm was developed. The numerical algorithm was based on the Lippmann-Schwinger equation for the scattering of a twodimensional plane wave at multiple coupled disk arrays. The aim of this thesis was to verify the numerical algorithm using two analytical solutions, namely the scattering of a plane wave at a single disk and the scattering of a spherical wave at a single disk. All three solutions were solved for a simple and comparable problem, i.e. scattering at a single disk. The comparison between the analytical plane wave scattering solution and the numerical solution based on the Lippmann-Schwinger equation showed agreement. The appearance and type of resonance found in the numerical solution was highly dependent on the grid ressolution. Based on results of this thesis it is obvious that the numerical solution based on the Lippmann-Schwinger equation is a stable program converging to the exact result, when the grid resolution is increased. We further expected to find the resonance wavenumbers that were detected in the analytical plane wave scattering program, by considering the S-matrix of the analytical spherical wave scattering. However, a comparison between these solutions revealed no similarities. In order to study the analytical solution for the spherical wave in this thesis we considered only the real part of the S-matrix. An analysis of the real and imaginary part of the S-matrix seems to be required to study the resonances in the analytical spherical wave scattering.Nanostrukturer med dielektriske egenskaper, slik som sfæriske nanoavtrykk, har vist seg som et lovende alternativ for effektivisering av lys-fangst i tynne solceller. Noe av den økte effektiviteten kan forklares med resonanser kalt Whispering gallery moder. Begrunnelsen for denne økningen er ikke fullt forstått, og hypotesen er at nanostrukturens parametere og koblede moder kan være direkte relatert til absorpsjon. En numerisk algoritme basert på Lippmann-Schwinger ligningen for spredning av en to-dimensjonal planbølge på flere koblede disksett, ble utviklet for å studere Whispering gallery moder og koblede moder i nanostrukturer samt parameterne av nanostrukturene. Målet for denne oppgaven var å verifisere den numeriske algoritmen ved hjelp av to analytiske løsninger, nemlig spredningen av en planbølge på en enkel disk og spredningen av en sfærisk bølge på en enkel disk. Alle tre program ble løst for et enkelt og sammenlignbart problem, dvs. spredning ved en enkelt disk. En sammenligning mellom den analytiske planbølge løsningen og den numeriske løsningen basert på Lippmann-Schwinger ligningen viste Whispering gallery resonanser på omtrent samme bølgenummer. Plasseringen av bølgenummer og type resonans som oppstår med den numeriske løsningen er sterkt avhengig av gitter oppløsningen. Basert på resultatene i denne oppgaven er det åpenbart at den numeriske løsningen basert på Lippmann-Schwinger ligningen er et stabil program som konvergerer til det nøyaktige resultatet, når gitteret oppløsningen økes. Det var også ventet noen likheter mellom den analytiske planbølgeløsningen og den analytiske sfæriske bølgeløsningen. En sammenligning mellom disse løsningene viste ingen likheter. For å studere den analytiske løsningen for den sfæriske bølgen i denne avhandling er det bare sett på den reelle delen av S-matrisen. En analyse av den reelle og imaginære delen av S-matrisen er nødvendig for å studere resonanser i den analytiske sfæriske bølgeløsningen.M-M

Clathrin-independent endocytosis: from nonexisting to an extreme degree of complexity

Today it is generally accepted that there are several endocytic mechanisms, both the clathrin-dependent one and mechanisms which operate without clathrin and with different requirements when it comes to dynamin, small GTP-binding proteins of the Rho family and specific lipids. It should be noted that clathrin-independent endocytosis can occur even when the cholesterol level in the membrane has been reduced to so low levels that caveolae are gone and clathrin-coated membrane areas are flat. Although new investigators in the field take it for granted that there is a multitude of entry mechanisms, it has taken a long time for this to become accepted. However, more work needs to be done, because one can still ask the question: How many endocytic mechanisms does a cell have, what are their function, and how are they regulated? This article describes some of the history of endocytosis research and attempts to give an overview of the complexity of the mechanisms and their regulation

Whispering gallery resonances in dielectric disk

Dielectric nanostructures, such as spherical nanoimprints, have emerged as a promising alternative for efficiency enhancement by light-trapping in thin solar cells. Some of the effectivity increase can be explained by resonant modes called Whispering gallery modes. The rationale of this increase is not fully understood and the hypothesis is that nanostructure parameters and coupled modes can be directly related to the absorption resonance. In order to study Whispering gallery modes and coupled modes in nanostructures in addition to the parameters of the nanostructures, a numerical algorithm was developed. The numerical algorithm was based on the Lippmann-Schwinger equation for the scattering of a twodimensional plane wave at multiple coupled disk arrays. The aim of this thesis was to verify the numerical algorithm using two analytical solutions, namely the scattering of a plane wave at a single disk and the scattering of a spherical wave at a single disk. All three solutions were solved for a simple and comparable problem, i.e. scattering at a single disk. The comparison between the analytical plane wave scattering solution and the numerical solution based on the Lippmann-Schwinger equation showed agreement. The appearance and type of resonance found in the numerical solution was highly dependent on the grid ressolution. Based on results of this thesis it is obvious that the numerical solution based on the Lippmann-Schwinger equation is a stable program converging to the exact result, when the grid resolution is increased. We further expected to find the resonance wavenumbers that were detected in the analytical plane wave scattering program, by considering the S-matrix of the analytical spherical wave scattering. However, a comparison between these solutions revealed no similarities. In order to study the analytical solution for the spherical wave in this thesis we considered only the real part of the S-matrix. An analysis of the real and imaginary part of the S-matrix seems to be required to study the resonances in the analytical spherical wave scattering.Nanostrukturer med dielektriske egenskaper, slik som sfæriske nanoavtrykk, har vist seg som et lovende alternativ for effektivisering av lys-fangst i tynne solceller. Noe av den økte effektiviteten kan forklares med resonanser kalt Whispering gallery moder. Begrunnelsen for denne økningen er ikke fullt forstått, og hypotesen er at nanostrukturens parametere og koblede moder kan være direkte relatert til absorpsjon. En numerisk algoritme basert på Lippmann-Schwinger ligningen for spredning av en to-dimensjonal planbølge på flere koblede disksett, ble utviklet for å studere Whispering gallery moder og koblede moder i nanostrukturer samt parameterne av nanostrukturene. Målet for denne oppgaven var å verifisere den numeriske algoritmen ved hjelp av to analytiske løsninger, nemlig spredningen av en planbølge på en enkel disk og spredningen av en sfærisk bølge på en enkel disk. Alle tre program ble løst for et enkelt og sammenlignbart problem, dvs. spredning ved en enkelt disk. En sammenligning mellom den analytiske planbølge løsningen og den numeriske løsningen basert på Lippmann-Schwinger ligningen viste Whispering gallery resonanser på omtrent samme bølgenummer. Plasseringen av bølgenummer og type resonans som oppstår med den numeriske løsningen er sterkt avhengig av gitter oppløsningen. Basert på resultatene i denne oppgaven er det åpenbart at den numeriske løsningen basert på Lippmann-Schwinger ligningen er et stabil program som konvergerer til det nøyaktige resultatet, når gitteret oppløsningen økes. Det var også ventet noen likheter mellom den analytiske planbølgeløsningen og den analytiske sfæriske bølgeløsningen. En sammenligning mellom disse løsningene viste ingen likheter. For å studere den analytiske løsningen for den sfæriske bølgen i denne avhandling er det bare sett på den reelle delen av S-matrisen. En analyse av den reelle og imaginære delen av S-matrisen er nødvendig for å studere resonanser i den analytiske sfæriske bølgeløsningen.M-M

Interplay between Toxin Transport and Flotillin Localization

The flotillin proteins are localized in lipid domains at the plasma membrane as well as in intracellular compartments. In the present study, we examined the importance of flotillin-1 and flotillin-2 for the uptake and transport of the bacterial Shiga toxin (Stx) and the plant toxin ricin and we investigated whether toxin binding and uptake were associated with flotillin relocalization. We observed a toxin-induced redistribution of the flotillins, which seemed to be regulated in a p38-dependent manner. Our experiments provide no evidence for a changed endocytic uptake of Stx or ricin in cells silenced for flotillin-1 or -2. However, the Golgi-dependent sulfation of both toxins was significantly reduced in flotillin knockdown cells. Interestingly, when the transport of ricin to the ER was investigated, we obtained an increased mannosylation of ricin in flotillin-1 and flotillin-2 knockdown cells. The toxicity of both toxins was twofold increased in flotillin-depleted cells. Since BFA (Brefeldin A) inhibits the toxicity even in flotillin knockdown cells, the retrograde toxin transport is apparently still Golgi-dependent. Thus, flotillin proteins regulate and facilitate the retrograde transport of Stx and ricin

Samspillprosjekter i bygg- og anleggsbransjen

publishedVersio

Cross‐formational flow and salinity sources inferred from a combined study of helium concentrations, isotopic ratios, and major elements in the Marshall aquifer, southern Michigan

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95014/1/ggge741.pd

Bone marrow stroma-derived PGE2 protects BCP-ALL cells from DNA damage-induced p53 accumulation and cell death

Background B cell precursor acute lymphoblastic leukaemia (BCP-ALL) is the most common paediatric cancer. BCP-ALL blasts typically retain wild type p53, and are therefore assumed to rely on indirect measures to suppress transformation-induced p53 activity. We have recently demonstrated that the second messenger cyclic adenosine monophosphate (cAMP) through activation of protein kinase A (PKA) has the ability to inhibit DNA damage-induced p53 accumulation and thereby promote survival of the leukaemic blasts. Development of BCP-ALL in the bone marrow (BM) is supported by resident BM-derived mesenchymal stromal cells (MSCs). MSCs are known to produce prostaglandin E2 (PGE2) which upon binding to its receptors is able to elicit a cAMP response in target cells. We hypothesized that PGE2 produced by stromal cells in the BM microenvironment could stimulate cAMP production and PKA activation in BCP-ALL cells, thereby suppressing p53 accumulation and promoting survival of the malignant cells. Methods Primary BCP-ALL cells isolated from BM aspirates at diagnosis were cocultivated with BM-derived MSCs, and effects on DNA damage-induced p53 accumulation and cell death were monitored by SDS-PAGE/immunoblotting and flow cytometry-based methods, respectively. Effects of intervention of signalling along the PGE2-cAMP-PKA axis were assessed by inhibition of PGE2 production or PKA activity. Statistical significance was tested by Wilcoxon signed-rank test or paired samples t test. Results We demonstrate that BM-derived MSCs produce PGE2 and protect primary BCP-ALL cells from p53 accumulation and apoptotic cell death. The MSC-mediated protection of DNA damage-mediated cell death is reversible upon inhibition of PGE2 synthesis or PKA activity. Furthermore our results indicate differences in the sensitivity to variations in p53 levels between common cytogenetic subgroups of BCP-ALL. Conclusions Our findings support our hypothesis that BM-derived PGE2, through activation of cAMP-PKA signalling in BCP-ALL blasts, can inhibit the tumour suppressive activity of wild type p53, thereby promoting leukaemogenesis and protecting against therapy-induced leukaemic cell death. These novel findings identify the PGE2-cAMP-PKA signalling pathway as a possible target for pharmacological intervention with potential relevance for treatment of BCP-ALL

Calibration of regional groundwater flow models: Working toward a better understanding of site‐specific systems

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95491/1/wrcr9512.pd