Biomedical subjects

T Möller

Publications and source records attributed to T Möller.

At least 19 recordsLinked to original sources

PubMed2006

Reduced mortality for women with mammography-detected breast cancer in east Denmark and south Sweden.

The 5-year relative survival from breast cancer in Denmark is 10 percentage points lower than in Sweden. This difference has been demonstrated previously as being caused partly by more involved lymph nodes and larger tumours in Denmark. Sweden has had nationwide mammography-screening coverage since 1991, whereas this is still in its infancy in Denmark. In the search for an explanation for the remaining survival difference, patient delay was a likely candidate. This study compared patient delay and mammography-detection between two national regions. Data on patient delay and mammography were obtained from hospital records from 1989 and 1994, and analysed using Cox proportional hazard analysis of death within the first 5 years, with the factors age, country, delay/mammography detection and established patho-anatomic variables. A comparison of patient delay and mammography detection in 1989 and 1994 showed more mammography-detected tumours in south Sweden and more women with long delay in east Denmark. Mammography detection, but not long patient delay, had a significant effect on the death hazard when adjusting for patho-anatomic risk factors. The hazard ratio was not eliminated in 1989, but in 1994, the hazard ratio between east Denmark and south Sweden was reduced from 1.3 to 1.1. In conclusion, patient delay did not appear to have any effect on 5-year survival when adjusting for patho-anatomic factors, but tumour detection by mammography affected survival favourably and partly explained the survival difference between east Denmark and south Sweden.

Adult↗

PubMed2005

Improved separation methods for the recovery of (82)Sr from irradiated targets.

(82)Rb is a short-lived positron-emitting isotope (T(1/2)=75 s) that is increasingly being used in PET to study blood flow through the heart and brain. This isotope is supplied to physicians in the form of a generator where the parent isotope, (82)Sr, is immobilized onto an ion exchange column allowing the (82)Rb to be eluted with isotonic saline as required. (82)Sr is manufactured by the proton irradiation of molybdenum, rubidium chloride or rubidium metal targets followed by complex separations to recover the (82)Sr. A number of inorganic ion exchange materials were evaluated for their ability to remove (82)Sr from simulated target solutions and compared with currently used organic ion exchange resins. Sodium nonatitanate was identified as a replacement for current resins as a potential material that would simplify target processing and improve the yield of (82)Sr from each target.

Chromatography, Ion Exchange↗

PubMed2005

Photoelectron spectroscopic investigations of chemical bonding in organically stabilized PbS nanocrystals.

The surface structure of organically capped PbS nanocrystals using synchrotron radiation excited core-level photoelectron spectroscopy has been studied. The nanocrystallites prepared by methods of colloidal chemistry have average diameters of 3.1, 3.9, 4.6, and 7.6 nm with narrow size distributions and are stabilized either with oleic acid only or with a combination of trioctylphosphine and oleic acid as ligands. High resolution photoelectron spectroscopy measurements allowed the surface structure to be studied and in particular how the organic ligands bind to the surface of the PbS nanocrystals to be elucidated. The results indicate that the trioctylphosphine ligands passivate only the surface S sites while oleic acid ligands appear to bind mainly to Pb sites.

Journal Article↗

PubMed2005

Molecular limits to the quantum confinement model in diamond clusters.

The electronic structure of monodispersed, hydrogen-passivated diamond clusters (diamondoids) in the gas phase has been studied with x-ray absorption spectroscopy. The data show that the bulk-related unoccupied states do not exhibit any quantum confinement. Additionally, density of states below the bulk absorption edge appears, consisting of features correlated to CH and CH2 hydrogen surface termination, resulting in an effective redshift of the lowest unoccupied states. The results contradict the commonly used and very successful quantum confinement model for semiconductors, which predicts increasing band edge blueshifts with decreasing particle size. Our findings indicate that in the ultimate size limit for nanocrystals a more molecular description is necessary.

Journal Article↗

PubMed2005

The effect of nanocrystal surface structure on the luminescence properties: photoemission study of HF-etched InP nanocrystals.

InP nanocrystals with narrow size distribution and mean particle diameter tunable from approximately 2 up to approximately 7 nm were synthesized via the dehalosilylation reaction between InCl3 and tris(trimethylsilyl)phosphine. Specific capping of the nanocrystal surface with a shell of organic ligands protects the nanocrystals from oxidation and provides solubility of the particles in various organic solvents. InP nanocrystals with enhanced photoluminescence (PL) efficiency were obtained from the initial nanocrystals by photoassisted etching of the nanocrystal surface with HF. The resulting PL quantum efficiency of InP nanocrystals dispersed in n-butanol is about three orders of magnitude higher when compared to the nonetched InP samples and approaches approximately 40% at room temperature. High-resolution photoelectron spectroscopy with the use of synchrotron radiation was applied to reveal the changes of the nanocrystal surface responsible for the dramatic improvement of the PL efficiency. The analysis of high-resolution P 2p core-level spectra confirmed significant changes of the nanocrystal surface structure induced by the postpreparative treatments and allowed us to propose the description of the etching mechanism. In the nonetched InP nanocrystals, some surface P atoms generate energy states located inside the band gap which provide nonradiative recombination pathways. Photoassisted treatment of InP nanocrystals with HF results in selective removal of these phosphorous atoms from the nanocrystal surface. The reconstructed surface of the etched InP nanocrystals is terminated mainly with In atoms and is efficiently passivated with tri-n-octylphosphine oxide ligands.

Journal Article↗

PubMed2005

Emission of thermally activated electrons from rare gas clusters irradiated with intense VUV light pulses from a free electron laser.

The ionization dynamics of Ar and Xe clusters irradiated with intense vacuum ultraviolet light from a free-electron laser is investigated using photoelectron spectroscopy. Clusters comprising between 70 and 900 atoms were irradiated with femtosecond pulses at 95 nm wavelength (approximately 13 eV photon energy) and a peak intensity of approximately 4 x 10(12) W/cm2. A broad thermal distribution of emitted electrons from clusters with a maximum kinetic energy up to 30-40 eV is observed. The observation of relatively low-energy photoelectrons is in good agreement with calculations using a time-dependent Thomas-Fermi model and gives experimental evidence of an outer ionization process of the clusters, due to delayed thermoelectronic emission.

Journal Article↗

PubMed2005

Multiple ionization of rare gas atoms irradiated with intense VUV radiation.

The interaction of intense vacuum-ultraviolet radiation from a free-electron laser with rare gas atoms is investigated. The ionization products of xenon and argon atomic beams are analyzed with time-of-flight mass spectroscopy. At 98 nm wavelength and approximately 10(13) W/cm(2) multiple charged ions up to Xe6+ (Ar4+) are detected. From the intensity dependence of multiple charged ion yields the mechanisms of multiphoton processes were derived. In the range of approximately 10(12)-10(13) W/cm(2) the ionization is attributed to sequential multiphoton processes. The production of multiple charged ions saturates at 5-30 times lower power densities than at 193 and 564 nm wavelength, respectively.

Journal Article↗

PubMed2005

EEG coherence reflects regional corpus callosum area in Alzheimer's disease.

OBJECTIVE: Correlations between corpus callosum size and interhemispheric EEG coherence were investigated as measures of interhemispheric connectivity in patients with Alzheimer's disease. METHODS: 11 patients underwent both magnetic resonance imaging and quantitative electroencephalography to assess corpus callosum size and interhemispheric coherence. For comparison, corpus callosum size was measured in 24 healthy elderly control subjects. RESULTS: Corpus callosum cross sectional area was significantly reduced in Alzheimer patients relative to controls. Posterior interhemispheric coherence (alpha and beta frequencies) correlated significantly with the size of posterior corpus callosum area, and anterior coherence (delta, theta, and alpha frequencies) with the size of anterior corpus callosum area in the Alzheimer patients. CONCLUSION: Region specific correlations between corpus callosum size and EEG coherence suggest that the decline in interhemispheric connectivity in Alzheimer's disease results from a specific loss of cortical association neurones projecting through the corpus callosum.

Aged↗

PubMed2004

Interaction of argon clusters with intense VUV-laser radiation: the role of electronic structure in the energy-deposition process.

The response of Ar clusters to intense vacuum-ultraviolet pulses is investigated with photoion spec-troscopy. By varying the laser wavelength, the initial excitation was either tuned to absorption bands of surface or bulk atoms of clusters. Multiple ionization is observed, which leads to Coulomb explosion. The efficiency of resonant 2-photon ionization for initial bulk and surface excitation is compared with that of the nonresonant process at different laser intensities. The specific electronic structure of clusters plays almost no role in the explosion dynamics at a peak intensity larger than 1.8 x 10(12) W/cm(2). The inner ionization of atoms for resonant and nonresonant excitation is then saturated and the energy deposition is mainly controlled by the plasma heating rate. Molecular dynamics simulations indicate that standard collisional heating cannot fully account for the strong energy absorption.

Journal Article↗

PubMed2004

New ion exchange materials for use in a 82Sr/82Rb generator.

82Rb is a short-lived positron-emitting isotope (T1/2 = 75 s) that is increasingly being used in positron emission tomography for the evaluation of myocardial perfusion. The short half-life of 82Rb results in rapid decay of the administered radioactivity allowing repeat scans to be performed after a relatively short time interval. The 82Rb is available from a 82Sr/82Rb generator in which the 82Sr parent is immobilized on an ion exchange column and 82Rb eluted when required. Consequently, suitable ion exchangers for use in a generator must have a very high affinity for strontium and a negligible affinity for rubidium, allowing the pure 82Rb to be safely and efficiently eluted in high yields. This study evaluated a number of strontium-selective ion exchange materials using batch experiments and identified sodium nonatitanate as the best material for use in a 82Sr/82Rb generator.

Chromatography, Ion Exchange↗

PubMed2004

Can the survival difference between breast cancer patients in Denmark and Sweden 1989 and 1994 be explained by patho-anatomical variables?--a population-based study.

Analyses of data from cancer registries have shown a 10% unit difference in 5-year relative survival between Danish and Swedish patients with breast cancer. This study investigates the effect of age and patho-anatomic variables on this survival difference. Hospital records were collected for women over 40 years of age diagnosed in 1989 or 1994 in east Denmark and south Sweden; patho-anatomical variables and survival were compared between 2289 Danish and 1715 Swedish women. Tumours were smaller, node-negative axillae more frequent and well-differentiated tumours almost 10% more frequent in Sweden. A superior 5-year relative survival in Sweden was found in the 50- to 79-year age group. The adjusted hazard rate ratio between countries was 1.7 in 1989 and 1.3 in 1994. Conditional survival after surviving the first 5 years was similar for the two countries. Adjusting for patho-anatomical variables reduced but did not eliminate the higher risk of death among the Danish patients. Higher population death rates could explain some but not all of the residual elevated risk for Danish women.

Age of Onset↗

PubMed2003

Experimental evidence for interatomic coulombic decay in Ne clusters.

Electron spectra of photoexcited Ne clusters are shown to display a signal at low kinetic energies that is neither present in the Ne monomer nor at photon energies below the inner-valence 2s threshold. These findings are strong evidence for the existence of interatomic Coulombic decays (ICD), a mechanism that was recently predicted theoretically [Phys. Rev. Lett. 79, 4778 (1997)]]. In ICD, an inner-valence hole state in a weakly bonded system can undergo ultrafast relaxation due to energy transfer to a neighboring atom, followed by electron emission from this neighboring site.

Journal Article↗

PubMed2003

Breast conservation surgery, with and without radiotherapy, in women with lymph node-negative breast cancer: a randomised clinical trial in a population with access to public mammography screening.

The effect of postoperative radiotherapy after sector resection for stage I-II lymph node-negative breast cancer was evaluated in a patient population with access to public mammographical screening. 1187 women were randomised to no further treatment or postoperative radiotherapy following a standardised sector resection and axillary dissection. Radiation was administered to a dose of 48-54 Gy. Median age was 60 years, and median size of the detected tumours was 12 mm. Of the women 65% had their tumours detected by mammographical screening. The relative risk (RR) of ipsilateral breast recurrence was significantly higher in the non-irradiated patients compared with the irradiated patients, RR=3.33 (95% Confidence Interval (CI) 2.13-5.19, P<0.001). The corresponding cumulative incidence at 5 years was 14% versus 4%, respectively. Overall survival (OS) was similar, RR=1.16 (95% CI 0.81-1.65, P=0.41), with 5 year probabilities of 93 and 94%, respectively. Recurrence-free survival (RFS) at 5 years was significantly lower in the non-irradiated women, 77% versus 88% (P<0.001). Although women above 49 years of age, whose tumours were detected with mammographical screening, had the lowest rate of ipsilateral breast recurrence in this study, the cumulative incidence of such event amounted to 10% at 5 years if radiotherapy was not given. Such a recurrence rate has been considered as unacceptably high, but is, however, in the same range as that reported after lumpectomy and postoperative radiotherapy in published series.

Adult↗

PubMed2003

Cancer prevalence in Northern Europe: the EUROPREVAL study.

BACKGROUND: Information on cancer prevalence is of importance for health planning and resource allocation, but is not always available. In order to obtain such data in a comparable way a systematic evaluation of cancer prevalence in Europe was undertaken within the EUROPREVAL project. PATIENTS AND METHODS: Standardised data were collected from 38 population-based registries on almost 3 million cancer patients diagnosed between 1970 and 1992. The prevalence of 11 specific cancer types was estimated at the index date of 31 December 1992. This study deals with the northern countries Denmark, Estonia, Finland, Iceland and Sweden. RESULTS: There were large differences between these countries, Sweden having the highest prevalence rate of 3050 per 100 000 and Estonia the lowest, 1339 per 100 000. This difference is mainly due to a high proportion of cancers with favourable prognosis such as breast cancer, prostate cancer and melanoma, better survival and longer life expectancy in Sweden, whereas Estonia has a higher proportion of stomach and lung cancer with poor prognosis, worse survival and much shorter life expectancy, especially for males. For most tumour types, the Nordic countries did better than Estonia. There are indications that cancer patients in Estonia, as well as in Denmark, have a more advanced stage at diagnosis and that the Estonian health-care system is less efficient. CONCLUSIONS: Despite many similarities and a common historical background, the northern countries in Europe that participated in the EUROPREVAL study display quite different cancer patterns and prevalence. Reasons for these variations are discussed.

Adolescent↗

PubMed2003

European health systems and cancer care.

INTRODUCTION: Data on the survival of all incident cases collected by population-based cancer registries make it possible to evaluate the overall performance of diagnostic and therapeutic actions on cancer in those populations. EUROCARE-3 is the third round of the EUROCARE project, the largest cancer registry population based collaborative study on survival in European cancer patients. The EUROCARE-3 study analysed the survival of cancer patients diagnosed from 1990 to 1994 and followed-up to 1999. Sixty-seven cancer registries of 22 European countries characterised by differing health systems participated in the study. This paper includes essays providing brief overviews of the state and evolution of the health systems of the considered countries and comments on the relation between cancer survival in Europe and some European macro-economic and health system indicators, in the 1990s. OVERVIEW OF THE EUROPEAN HEALTH SYSTEMS: The European health systems underwent a great deal of reorganisation in the last decade; a general tendency being to facilitate expanding involvement of the private sector in health care, a process which occurred mainly in the eastern countries (i.e. the Czech Republic, Estonia, Poland, Slovakia and Slovenia). In contrast, organisational changes in the northern European countries (i.e. Denmark, Iceland, Finland and Sweden) tended to confirm the established public sector systems. Other countries, including the UK and some southern European countries (i.e. England, Scotland, Wales, Malta and Italy) have reduced the public role while the systems remain basically public, at least at present. Our findings clearly suggest that cancer survival (all cancer combined) is related to macro-economic variables such as the gross domestic product (GDP), the total national (public and private) expenditure on health (TNEH) and the total public expenditure on health (TPEH). We found, however, that survival is related to wealth (GDP), but only up to a certain level, after which survival continues to be related to the level of health investment (both TNEH and TPEH). According to the Organisation for Economic Co-operation and Development (OECD), the TNEH increased during the 1990s in all EUROCARE-3 countries, while the ratio of TPEH to TNEH reduced in all countries except Portugal. CONCLUSIONS: Cancer survival depends on the widespread application of effective diagnosis and treatment modalities, but our enquiry suggests that the availability of these depends on macro-economic determinants, including health and public health investment. Analysis of the relationship between health system organisation and cancer outcome is complicated and requires more information than is at present available. To describe cancer and cancer management in Europe, the European Cancer Health Indicator Project (EUROCHIP) has proposed a list of indicators that have to be adopted to evaluate the effects on outcome of proposed health system modifications.

Community Health Planning↗

PubMed2003

EUROCARE-3: survival of cancer patients diagnosed 1990-94--results and commentary.

EUROCARE-3 analysed the survival of 1815584 adult cancer patients diagnosed from 1990 to 1994 in 22 European countries. The results are reported in tables, one per cancer site, coded according to the International Classification of Diseases (ICD)-9 classification. The main findings of the tables are summarised and commented on in this article. For most solid cancers, wide differences in survival between different European populations were found, as also reported by EUROCARE-1 and EUROCARE-2, despite a remarkable (10%) overall increase in cancer survival from 1985 to 1994. Survival was highest in northern Europe (Sweden, Norway, Finland and Iceland), and fairly good in central-southern Europe (France, Switzerland, Austria and Spain). Survival was particularly low in eastern Europe, low in Denmark and the UK, and fairly low in Portugal and Malta. The mix of tumour stage at diagnosis explains much of the survival differences for cancers of the digestive tract, female reproductive system, breast, thyroid, and also skin melanoma. For tumours of the urinary tract and prostate, the differences were explained mainly by differences in diagnostic criteria and procedures. The case mix by anatomic subsite largely explains differences in survival for head and neck cancers. For oesophagus, pancreas, liver and brain cancer, with poor prognoses, survival differences were limited. Tumours, for which highly effective treatments are available, such as testicular cancer, Hodgkin's lymphoma and some haematological malignancies, had fairly uniform survival across Europe. Survival for all tumours combined (an indicator of the overall cancer care performance of a nation's health system) was better in young than old patients, and better in women than men. The affluence of countries influenced overall cancer survival through the availability of adequate diagnostic and treatment procedures, and screening programmes.

Brain Neoplasms↗

PubMed2002

Multiple ionization of atom clusters by intense soft X-rays from a free-electron laser.

Intense radiation from lasers has opened up many new areas of research in physics and chemistry, and has revolutionized optical technology. So far, most work in the field of nonlinear processes has been restricted to infrared, visible and ultraviolet light, although progress in the development of X-ray lasers has been made recently. With the advent of a free-electron laser in the soft-X-ray regime below 100 nm wavelength, a new light source is now available for experiments with intense, short-wavelength radiation that could be used to obtain deeper insights into the structure of matter. Other free-electron sources with even shorter wavelengths are planned for the future. Here we present initial results from a study of the interaction of soft X-ray radiation, generated by a free-electron laser, with Xe atoms and clusters. We find that, whereas Xe atoms become only singly ionized by the absorption of single photons, absorption in clusters is strongly enhanced. On average, each atom in large clusters absorbs up to 400 eV, corresponding to 30 photons. We suggest that the clusters are heated up and electrons are emitted after acquiring sufficient energy. The clusters finally disintegrate completely by Coulomb explosion.

Journal Article↗

PubMed2002

Bubble formation and decay in 3He and 4He clusters.

The energy transfer in 3He and 4He clusters electronically excited by monochromatic synchrotron radiation is investigated by luminescence spectroscopy. Depending on the cluster size and the isotopic constitution, either sharp, broadened, or shifted emission bands of single He molecules are observed. The spectral features show that He molecules emit light either within a bubble inside the cluster or in the vacuum after desorption from the cluster. From the luminescence intensity, the cluster diameter, and the radiative lifetime, an average velocity of approximately 7 m/s of bubbles in 4He clusters could be deduced. In the nonsuperfluid 3He clusters this velocity was observed to be significantly lower.

Journal Article↗