Nanoscale density fluctuations in swift heavy ion irradiated amorphous SiO2

We report on the observation of nanoscale density fluctuations in 2 μm thick amorphous SiO₂ layers irradiated with 185 MeV Au ions. At high fluences, in excess of approximately 5 × 10¹² ions/cm², where the surface is completely covered by ion tracks, synchrotron small angle x-ray scattering measurements reveal the existence of a steady state of density fluctuations. In agreement with molecular dynamics simulations, this steady state is consistent with an ion track “annihilation” process, where high-density regions generated in the periphery of new tracks fill in low-density regions located at the center of existing tracks.The authors acknowledge the Australian Research Council and the Australian Synchrotron Research Program for financial support and thank the staff at the ANU Heavy Ion facility for their continued technical assistance. O.P., F.D., and K.N. acknowledge financial support from the Academy of Finland under its Centre of Excellence program as well as the OPNA project, and grants of computer capacity from CSC

Aspects of power corrections in hadron-hadron collisions

The program of understanding inverse-power law corrections to event shapes and energy flow observables in e+ e- annihilation to two jets and DIS (1+1) jets has been a significant success of QCD phenomenology over the last decade. The important extension of this program to similar observables in hadron collisions is not straightforward, being obscured by both conceptual and technical issues. In this paper we shed light on some of these issues by providing an estimate of power corrections to the inter-jet E_t flow distribution in hadron collisions using the techniques that were employed in the e+ e- annihilation and DIS cases.Comment: 15 pages, 1 figure, uses JHEP3.cl

UV light-blocking contact lenses protect against short-term UVB-induced limbal stem cell niche damage and inflammation

UVB irradiation has been linked to pathogenesis of pterygium, a conjunctival tumor growing onto transparent cornea, the windscreen of the eye. Due to corneal anatomy, ambient UVB irradiation is amplified at the stem cell-containing nasal limbus. The aim of this study was to analyse the effect of a UV-blocking contact lens (UVBCL, senofilcon A, Class 1 UV blocker) on limbal epithelial cells and fibroblasts under UVB irradiation compared to a non-UVB-blocking contact lens. UVBCL prevented UVB-induced DNA damage (as assessed by cyclobutane pyrimidine dimer immunostaining) as well as a decrease in proliferation and scratch wound closure rate of both limbal epithelial and fibroblast cells. Similarly, UVBCL protected limbal epithelial cells from UVB-induced loss of their phenotype in terms of colony forming efficiency and stem cell marker expression (ABCB5, P63α, integrin β1) compared to controls. Moreover, with UVBCL pro-inflammatory cytokines such as TNFα and MCP1 remained unchanged. These data demonstrate the significance of UV-protection in preserving the limbal niche in response to at least short-term UVB. Our data support the use of UVBCL in protecting limbal niche cells, especially after limbal stem cell transplantation and in patients after pterygium surgery, to help prevent recurrences

UV light-blocking contact lenses protect against short-term UVB-induced limbal stem cell niche damage and inflammation

UVB irradiation has been linked to pathogenesis of pterygium, a conjunctival tumor growing onto transparent cornea, the windscreen of the eye. Due to corneal anatomy, ambient UVB irradiation is amplified at the stem cell-containing nasal limbus. The aim of this study was to analyse the effect of a UV-blocking contact lens (UVBCL, senofilcon A, Class 1 UV blocker) on limbal epithelial cells and fibroblasts under UVB irradiation compared to a non-UVB-blocking contact lens. UVBCL prevented UVB-induced DNA damage (as assessed by cyclobutane pyrimidine dimer immunostaining) as well as a decrease in proliferation and scratch wound closure rate of both limbal epithelial and fibroblast cells. Similarly, UVBCL protected limbal epithelial cells from UVB-induced loss of their phenotype in terms of colony forming efficiency and stem cell marker expression (ABCB5, P63α, integrin β1) compared to controls. Moreover, with UVBCL pro-inflammatory cytokines such as TNFα and MCP1 remained unchanged. These data demonstrate the significance of UV-protection in preserving the limbal niche in response to at least short-term UVB. Our data support the use of UVBCL in protecting limbal niche cells, especially after limbal stem cell transplantation and in patients after pterygium surgery, to help prevent recurrences

High precision fundamental constants at the TeV scale

This report summarizes the proceedings of the 2014 Mainz Institute for Theoretical Physics (MITP) scientific program on "High precision fundamental constants at the TeV scale". The two outstanding parameters in the Standard Model dealt with during the MITP scientific program are the strong coupling constant $\alpha_s$ and the top-quark mass $m_t$. Lacking knowledge on the value of those fundamental constants is often the limiting factor in the accuracy of theoretical predictions. The current status on $\alpha_s$ and $m_t$ has been reviewed and directions for future research have been identified.Comment: 57 pages, 24 figures, pdflate

Congenital diaphragmatic hernia: the impact of embryological studies

In recent years, a substantial research effort within the specialty of pediatric surgery has been devoted to improving our knowledge of the natural history and pathophysiology of congenital diaphragmatic hernias (CDH) and pulmonary hypoplasia (PH). However, the embryological background has remained elusive because certain events of normal diaphragmatic development were still unclear and appropriate animal models were lacking. Most authors assume that delayed or inhibited closure of the diaphragm will result in a diaphragmatic defect that is wide enough to allow herniation of the gut into the fetal thoracic cavity. However, we feel that this assumption is not based on appropriate embryological observations. To clarify whether it was correct, we restudied the morphology of pleuroperitoneal openings in normal rat embryos. Shortly before, a model for CDH and PH had been established in rats using nitrofen (2,4-di-chloro-phenyl-p-nitrophenyl ether) as teratogen. We used this model in an attempt to answer the following questions: (1) When does the diaphragmatic defect appear? (2) Are the pleuroperitoneal canals the precursors of the diaphragmatic defect? (3) Why is the lung hypoplastic in babies and infants with CDH? In our study we made following observations: (1) The typical findings of CDH and PH cannot be explained by inhibited closure of the pleuroperitoneal "canals". In normal development, the pleuroperitoneal openings are always too small to allow herniation of gut into the thoracic cavity. (2) The maldevelopment of the diaphragm starts rather early in the embryonic period (5th week). The lungs of CDH rats are significantly smaller than those of control rats at the end of the embryonic period (8th week). (3) The maldevelopment of the lungs in rats with CDH is "secondary" to the defect of the diaphragm. (4) The defect of the lungs is "structural" rather than "functional". Complete spontaneous correction of these lung defects is unlikely even after fetal intervention. (5) The "fetal lamb model" does not completely mimic the full picture of CDH, because the onset of the defect lies clearly in the fetal period. We believe that our rat model is better. It is especially useful for describing the abnormal embryology of this lesion

Consecutive dosing of UVB irradiation induces loss of ABCB5 expression and activation of EMT and fibrosis proteins in limbal epithelial cells similar to pterygium epithelium

Pterygium pathogenesis is often attributed to a population of altered limbal stem cells, which initiate corneal invasion and drive the hyperproliferation and fibrosis associated with the disease. These cells are thought to undergo epithelial to mesenchymal transition (EMT) and to contribute to subepithelial stromal fibrosis. In this study, the presence of the novel limbal stem cell marker ABCB5 in clusters of basal epithelial pterygium cells co-expressing with P63α and P40 is reported. ABCB5-positive pterygium cells also express EMT-associated fibrosis markers including vimentin and α-SMA while their β-catenin expression is reduced. By using a novel in vitro model of two-dose UV-induced EMT activation on limbal epithelial cells, we could observe the dysregulation of EMT-related proteins including an increase of vimentin and α-SMA as well as downregulation of β-catenin in epithelial cells correlating to downregulation of ABCB5. The sequential irradiation of limbal fibroblasts also induced an increase in vimentin and α-SMA. Taken together, these data demonstrate for the first time the expression of ABCB5 in pterygium stem cell activity and EMT-related events while the involvement of limbal stem cells in pterygium pathogenesis is exhibited via sequential irradiation of limbal epithelial cells. The later in vitro approach can be used to further study the involvement of limbal epithelium UV-induced EMT in pterygium pathogenesis and help identify novel treatments against pterygium growth and recurrence

Bond length contraction in Au nanocrystals formed by ion implantation into thin SiO[sub 2]

Au nanocrystals (NCs) fabricated by ion implantation into thin SiO₂ and annealing were investigated by means of extended x-rayabsorption fine structure (EXAFS)spectroscopy and transmission electron microscopy. A bond length contraction was observed and can be explained by surface tension effects in a simple liquid-drop model. Such results are consistent with previous reports on nonembedded NCs implying a negligible influence of the SiO₂ matrix. Cumulant analysis of the EXAFS data suggests surface reconstruction or relaxation involving a further shortened bond length. A deviation from the octahedral closed shell structure is apparent for NCs of size 25Å.P. K. is grateful to the Humboldt Foundation in Germany for support. P.K., B.J., A.C., C.J.G., G.d.M.A., G.J.F., and M.C.R. were supported by the Australian Synchrotron Research Program

Drug regulatory-compliant validation of a qPCR assay for bioanalysis studies of a cell therapy product with a special focus on matrix interferences in a wide range of organ tissues

Quantitative polymerase chain reaction (qPCR) has emerged as an important bioanalytical method for assessing the pharmacokinetics of human-cell-based medicinal products after xenotransplantation into immunodeficient mice. A particular challenge in bioanalytical qPCR studies is that the different tissues of the host organism can affect amplification efficiency and amplicon detection to varying degrees, and ignoring these matrix effects can easily cause a significant underestimation of the true number of target cells in a sample. Here, we describe the development and drug regulatory-compliant validation of a TaqMan qPCR assay for the quantification of mesenchymal stromal cells in the range of 125 to 20,000 cells/200 L lysate via the amplification of a human-specific, highly repetitive α-satellite DNA sequence of the chromosome 17 centromere region HSSATA17. An assessment of matrix effects in 14 different mouse tissues and blood revealed a wide range of spike recovery rates across the different tissue types, from 11 to 174%. Based on these observations, we propose performing systematic spike-and-recovery experiments during assay validation and correcting for the effects of the different tissue matrices on cell quantification in subsequent bioanalytical studies by multiplying the back-calculated cell number by tissue-specific factors derived from the inverse of the validated percent recovery rate

Energy dependent saturation width of swift heavy ion shaped embedded Au nanoparticles

The transformation of Aunanoparticles (NPs) embedded in SiO₂ from spherical to rod-like shapes induced by swift heavy ion irradiation has been studied. Irradiation was performed with ¹⁹⁷Au ions at energies between 54 and 185 MeV. Transmission electron microscopy and small angle x-ray scatteringmeasurements reveal an energy dependent saturation width of the NP rods as well as a minimum size required for the NPs to elongate. The NP saturation width is correlated with the ion track diameter in the SiO₂. NP melting and in-plane strain in the irradiatedSiO₂ are discussed as potential mechanisms for the observed deformation.P.K. and M.C.R. thank the Australian Research Council for support. P.K., R.G., D.J.S., and M.C.R. were supported by the Australian Synchrotron Research Program, funded by the Commonwealth of Australia via the Major National Research Facilities Program