3,093 research outputs found
Photodynamic therapy of prostate cancer by means of 5-aminolevulinic acid-induced protoporphyrin IX - In vivo experiments on the dunning rat tumor model
No full textObjective: In order to expand the use of photodynamic therapy (PDT) in the treatment of prostate carcinoma (PCA), the aim of this study was to evaluate PDT by means of 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX ( PPIX) in an in vivo tumor model. Methods: The model used was the Dunning R3327 tumor. First of all, the pharmacokinetics and the localization of PPIX were obtained using fluorescence measurement techniques. Thereafter, PDT using 150 mg 5-ALA/kg b.w.i.v. was performed by homogenous irradiation of the photosensitized tumor (diode laser lambda = 633 nm). The tumors necrosis was determined histopathologically. Results: The kinetics of PPIX fluorescence revealed a maximum intensity in the tumor tissue within 3 and 4.5 h post-application of 5-ALA. At this time, specific PPIX fluorescence could be localized selectively in the tumor cells. The PDT-induced necrosis (n = 18) was determined to be 94 B 12% (range 60-100%), while the necrosis of the controls ( n = 12) differs significantly (p < 0.01), being less than 10%. Conclusion: These first in vivo results demonstrate the effective potential of 5-ALA-mediated PDT on PCA in an animal model. Copyright (C) 2004 S. Karger AG, Basel
Coherent atomic manipulation and cooling using composite optical pulse sequences
No full textThe laser cooling of atoms to ultracold temperatures has propelled many groundbreaking advances in fundamental research and precision measurement, through such applications as quantum simulators and interferometric sensors. Laser cooling remains, however, highly species-selective, and techniques for its application to molecules are still in their infancy.This thesis broadly concerns the development of laser cooling schemes, based on sequences of coherent optical pulses, which can in principle be applied to a wide range of species. We describe a cooling scheme, in which a velocity-selective impulse analogous to that in Doppler cooling is generated by a light-pulse Ramsey interferometer, and present a proof-of-concept demonstration of the scheme using ultracold rubidium-85 atoms as a test-bed. We realise an interferometer for the atoms, as they are in free-fall after release from a magneto-optical trap, by inducing stimulated Raman transitions between their ground hyperfine states. We provide a comprehensive characterisation of these Raman light-pulse interferometer optics, where particular attention is paid to light shift effects.Raman pulses, and indeed coherent operations in any quantum control system, unavoidably suffer from systematic errors in the control field intensity and frequency, and these lead to reductions in pulse fidelity and readout contrast. In parallel to the work on interferometric cooling in this thesis, we report our preliminary investigations into composite pulses, whereby 'naive' single pulses are replaced by sequences of rotations with tailored durations and phases, for improving pulse fidelity in the presence of inhomogeneities. We find that composite pulses can indeed be highly effective in our cold atom system, and propose that their application in such devices as interferometric sensors is a promising prospect
Ki-ras2 gene point mutations and dna methylation patterns in the dunning r-3327 rat dorsal prostatic adenocarcinoma system, 1996
No full textThe detection of point mutations in the Ki-ras2 gene in the first and second positions of codon 12 exon I of the Dunning Rat System has been successfully performed employing Polymerase Chain Reaction (PCR) techniques. Two sets of allele-specific oligonucleotide (ASO) primer panels were used differing from each other in their terminal 31 nucleotide ends. Utilizing the appropriate annealing temperatures, these primers only directed amplification on their complementary alleles containing codon 12 from PCR generated 94bp templates and genomic DNA extracted from the Dunning cell lines AT-1 (Anaplastic), AT-3, Mat-LyLu (Metastasis Lymph and Lung) and Mat-Lu (Metastasis Lung). Our investigations have revealed that the first and second positions of codon 12 have undergone either transitions or transversions suggesting a heterogeneous population of cells comprising the wild type (GGT) and several other sequence mutations. Dorsal prostate solid tissues used as controls revealed the wild type sequence, GG, at codon 12. Genomic DNA extracted from Dunning cell lines Mat-Lu and Mat-LyLu treated with the differentiation agent difluoromethylornithine (DFMO) and retinoic acid (RA) were used to detect reversion of point mutations for the Dunning R-3327 Prostatic Adenocarcinoma System in the Ki-ras2 gene of the first and second positions of codon 12 exon I. As a result, no reversions were detected for the first and second positions of codon 12 from either treatment. Genomic methylation patterns of non-treated Dunning R- 3327 cell lines AT-1, AT-3, Mat-LyLu and Mat-Lu, and Dunning R-3327 Mat-LyLu cells treated with difluoromethylornithine and retinoic acid were analyzed. Each of the cell lines were digested with Hpa II and Msp I restriction endonuclease enzymes used to characterize patterns at the interior cytosine of the sequence C'CGG. Identical molecular weight banding patterns were found for both Hpa II and Msp I digests in NDP (normal dorsal prostate) used as a control. Both treated and non-treated Dunning R- 3327 cells digested with Hpa II and Msp I displayed similar banding profiles completely altered from those seen in NDP solid tissues, indicative of a progressive loss of methylation at CCGG sites
The use of K(nd) Rydberg atoms to investigate low-energy electron-molecule interactions
No full textNegative ion formation through electron transfer in collisions between K(nd) Rydberg atoms (10 n 110) and C\sb7F\sb{14} and 1,1,1-C\sb2Cl\sb3F\sb3 is studied and provides a novel means to explore electron capture by these molecules at sub-thermal energies. The data suggest electron attachment to C\sb7F\sb{14} occurs through two channels, one leading to the formation of long-lived C\sb7F\sb{14}\sp- ions and the other to C\sb7F\sb{14}\sp- ions that experience rapid autodetachment. On the other hand, electron attachment to 1,1,1-C\sb2Cl\sb3F\sb3 results directly in dissociation and the formation of Cl\sp- ions. The present data are discussed in light of earlier results obtained with swarm and threshold photoelectron spectroscopy techniques
The application of Rydberg atoms to the study of electron attachment at subthermal energies
No full textLow energy electron interactions with C\sb2Cl\sb4 and C\sb6F\sb6 molecules have been studied by using Rydberg atoms. It is observed that the electron attachment process occurs through various channels. Collisions of Rydberg atoms with C\sb2Cl\sb4 molecules result in the formation of Cl\sp- ions and C\sb2Cl\sb4\sp- ions. The data suggest the presence of the long lived C\sb2Cl\sb4\sp- ions and that the C\sb2Cl\sb4\sp- ions undergo rapid autodetachment forming an electron and a neutral C\sb2Cl\sb4 molecule. Similar reactions with the C\sb6F\sb6 molecules result in the formation of both long lived C\sb6F\sb6\sp- ions and short lived C\sb6F\sb6\sp- ions, that suffer rapid autodetachment forming an electron and a neutral molecule. The present data are compared with the previous data obtained by Swarm and Threshold Photoelectron Spectroscopy techniques
Globalisation and New Realities for MNE-Developing Host Country Interaction
No full textGlobalisation has resulted in the increased mobility and knowledge intensity of the ownership advantages of MNEs, which they increasingly seek to utilise in conjunction with the created-asset intensive location advantages of countries. We highlight that that the relative opportunity sets (and thus bargaining positions) of both developing country host governments and MNEs varies by the stage of economic development and the motive of FDI. In general, globalisation has shifted the balance in favour of the MNE, and governments increasingly need to provide unique, non-replicable created assets in order to get foreign firms to be ''locked into'' these locations.international economics and trade ;
Decay energetics and lifetime measurements of transient negative ions using Rydberg atoms
No full textDissociative electron attachment to CFCl\sb3, CF\sb2Br\sb2, and 1,1,1- and 1,1,2-C\sb2Cl\sb3F\sb3 is studied by measuring the velocity and angular distributions of negative ions produced through electron transfer in collisions with velocity selected K(np) Rydberg atoms. Data analysis is done with the aid of Monte Carlo simulations. Measurements indicate that the mean lifetimes of the transient ions CFCl\sb3\sp{-*} and CF\sb2Br\sb2\sp{-*} are 3.5 ps and 4.5 ps respectively and that only a small fraction of the excess energy of reaction appears in translation. The 1,1,1-C\sb2Cl\sb3F\sb3 data show one reaction channel resulting in immediate dissociation with an ion lifetime of 0 ps, and a second channel associated with a longer lived intermediate, 0.1 to 1.0 ps. Only limited energy transfer occurs for the 1,1,2 isomer but the operative reaction channel(s) could not be identified. Possible reaction mechanisms are discussed with the aid of ab-initio calculations
Helium 2(3)S(1) optical pumping with lasers
No full textContinued improvement of a single-mode frequency-stabilized 1.083 m LNA laser developed at this laboratory has resulted in greater frequency stability and higher output power. Use of this laser with the Rice Flowing Helium Afterglow apparatus has resulted in considerable insight into Penning ionization reaction processes. Also, in the present work, a modified Coherent Inc. CR899-21 Ti:Sapphire laser is being used as a source of 1.083 m radiation. A simple technique using a confocal Fabry-Perot etalon and stabilized helium-neon laser is used to limit long-term drift in the laser output frequency to 1 MHz per day. Measurements using a beam of He(2\sp3S) atoms show that the laser can provide stable He(2\sp3S) optical pumping resulting in polarizations approaching 100%. The laser is also being employed in studies of He(2\sp3P) collisions at low temperatures using laser-induced fluorescence and line-shape analysis. (Abstract shortened with permission of author.
Studies of unimolecular dissociation reactions using Rydberg-atom techniques
No full textDissociative electron attachment reactions of the type K(nd) + AB K\sp+ + AB\sp{-*} K\sp+ + A\sp- + B have been investigated for polyatomic molecules BrCN, CF\sb2Br\sb2, CF\sb3Br and Fe(CO)\sb5. Rate constants for the formation of various negative ions were measured for a range of principal quantum numbers n. At high n (n 40), the Rydberg electron can be treated as 'essentially' free electron and the present data are compared with the free electron data obtained by the TPSA technique. At lower n, the free electron model must be modified to take into account post-attachment electrostatic interactions between the product ions and effects associated with the reduced size of the Rydberg atom.
The translational energy release in such reactions was measured using the TOF-PSD technique. Comparison with the excess energy of reaction for BrCN and CF\sb2Br\sb2 shows that the energy released by electron capture is well distributed among the internal modes of the intermediate negative ion prior to dissociation. In contrast, data for CF\sb3Br indicate that the electron capture takes place into a repulsive state resulting in the immediate dissociation of the intermediate negative ion before significant redistribution of excess energy can occur
European Union Foreign Direct Investment in China: Evidence from a Panel Study of EU Manufacturing Firms, 1998-2007
No full textThe paper examines determinants of the EU‘s FDI into the China by using a newly available Manufacturing firm-level data set for the period 1998-2007 from the State Statistical Bureau of China. The theoretical framework of the paper builds on Dunning's ownership–location–internalization (OLI) paradigm, incorporating the institutional determinants to test international production by EU firms in emerging market. The paper analyses recent trends and patterns of EU FDI and its firms‘ characteristics in China. This study applies both static and dynamic panel data approaches (fixed effects and GMM system estimators) to test the presence of agglomeration effect of past FDI. It finds that EU FDI in China is positively associated with export intensity and labour cost. However, technology and profitability of the firm show unexpected results, not lining with theory in the study. The results further suggest that locational factors with regard to macroeconomic and legal environment are also considered by EU firms when deciding on FDI in China. The findings have important implications for practitioners and policymaking
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