In vivo imaging of cellular proliferation in colorectal cancer using positron emission tomography

Background and aims: Positron emission tomography (PET) using 18F labelled 2-fluoro-2-deoxy-D-glucose (18FDG) is an established imaging tool, although the recent development of a biologically stable thymidine analogue [18F] 3'-deoxy-3-fluorothymidine (18FLT) has allowed PET to image cellular proliferation by utilising the salvage pathway of DNA synthesis. In this study, we have compared uptake of 18FLT and 18FDG with MIB-1 immunohistochemistry to evaluate the role of PET in quantifying in vivo cellular proliferation in colorectal cancer (CRC). Patients and methods: Patients with resectable, primary, or recurrent CRC were prospectively studied. Thirteen lesions from 10 patients (five males, five females), median age 68 years (range 54–87), were evaluated. Patients underwent 18FDG and 18FLT PET scanning. Tracer uptake within lesions was quantified using standardised uptake values (SUVs). Histopathological examination and MIB-1 immunohistochemistry were performed on all lesions, and proliferation quantified by calculating a labelling index (% of MIB-1 positively stained nuclei within 1500 tumour cells). Results: Histology confirmed adenocarcinoma in 12 of 13 lesions; the remaining lesion was reactive. All eight extrahepatic lesions were visualised using both 18FLT and 18FDG. Three of the five resected liver metastases were also avid for 18FLT and showed high proliferation, while the remaining two lesions which demonstrated no uptake of 18FLT had correspondingly very low proliferation. There was a statistically significant positive correlation (r =0.8, p<0.01) between SUVs of the tumours visualised with 18FLT and the corresponding MIB-1 labelling indices. No such correlation was demonstrated with 18FDG avid lesions (r =0.4). Conclusions: 18FLT PET correlates with cellular proliferation markers in both primary and metastatic CRC. This technique could provide a mechanism for in vivo grading of malignancy and early prediction of response to adjuvant chemotherapy

Effective scraping in a scraped surface heat exchanger: some fluid flow analysis

An outline of mathematical models that have been used to understand the behaviour of scraped surface heat exchangers is presented. In particular the problem of the wear of the blades is considered. A simple model, exploiting known behaviour of viscous flow in corners and in wedges, and accounting for the forces on the blade is derived and solutions generated. The results shows initial rapid wear but that the wear rate goes to zero

Search for the hero: an investigation into the sports heroes of British sports fans

This is an initial study into British sports fans’ heroes. A questionnaire was sent to 95 students (average age ¼ 19.75) to identify their sporting hero, the hero’s sport and nationality and the reasons for this choice. Football was the most common source of sports heroes, identified by 49% of participants with a sporting hero. The majority (60%, N ¼ 48) of heroes chosen by participants were British, with David Beckham the most popular choice. Differences were observed between the gender of participants, gender of hero chosen and the reasons for choosing the hero. The most common reason for selecting a hero was a personal trait rather than skill, while in the questionnaire a category of Local Affiliation was added to those suggested by previous work. It was concluded that to become a hero athletes should combine skill with devotion to family, charity work and a place in popular culture

Phylogenetic relationships of African Caecilians (Amphibia: Gymnophiona): insights from mitochondrial rRNA gene sequences

Africa (excluding the Seychelles) has a diverse caecilian fauna, including the endemic family Scolecomorphidae and six endemic genera of the more cosmopolitan Caeciliidae. Previous molecular phylogenetic studies have not included any caecilians from the African mainland. Partial 12S and 16S mitochondrial gene sequences were obtained for two species of the endemic African Scolecomorphidae and five species and four genera of African Caeciliids, aligned against previously reported sequences for 16 caecilian species, and analysed using parsimony, maximum likelihood, Bayesian and distance methods. Results are in agreement with traditional taxonomy in providing support for the monophyly of the African Caeciliid genera Boulengerula and Schistometopum and for the Scolecomorphidae. They disagree in indicating that the Caeciliidae is paraphyletic with respect to the Scolecomorphidae. Although more data from morphology and/or molecules will be required to resolve details of the interrelationships of the African caecilian genera, the data provide strong support for at least two origins of caecilians in which the eye is reduced and covered with bone, and do not support the hypotheses that the caecilian assemblages of Africa, and of East and of West Africa are monophyletic

Disks, Tori, and Cocoons: Emission and Absorption Diagnostics of AGN Environments

One of the most important problems in the study of active galaxies is understanding the detailed geometry, physics, and evolution of the central engines and their environments. The leading models involve an accretion disk and torus structure around a central dense object, thought to be a supermassive black hole. Gas found in the environment of AGN is associated with different structures: molecular accretion disks, larger scale atomic tori, ionized and neutral "cocoons" in which the nuclear regions can be embedded. All of them can be studied at radio wavelengths by various means. Here, we summarize the work that has been done to date in the radio band to characterize these structures. Much has been learned about the central few parsecs of AGN in the last few decades with contemporary instruments but the picture remains incomplete. In order to be able to define a more accurate model of this region, significant advances in sensitivity, spectral and angular resolution, and bandpass stability are required. The necessary advances will only be provided by the Square Kilometer Array and we discuss the possibilities that these dramatic improvements will open for the study of the gas in the central region of AGN.Comment: To appear in "Science with the Square Kilometer Array," eds. C. Carilli and S. Rawlings, New Astronomy Reviews (Elsevier: Amsterdam); 17 pages, 7 figures (four of them in separate gif/tif files) The full paper with high resolution images can be downloaded from http://www.astron.nl/~morganti/Papers/AGNenvironment.ps.g

Landau and dynamical instabilities of Bose-Einstein condensates with superfluid flow in a Kronig-Penney potential

We study the elementary excitations of Bose-Einstein condensates in a one-dimensional periodic potential and discuss the stability of superfluid flow based on the Kronig-Penney model. We analytically solve the Bogoliubov equations and calculate the excitation spectrum. The Landau and dynamical instabilities occur in the first condensate band when the superfluid velocity exceeds certain critical values, which agrees with the result of condensates in a sinusoidal potential. It is found that the onset of the Landau instability coincides with the point where the perfect transmission of low-energy excitations is forbidden, while the dynamical instability occurs when the effective mass is negative. It is well known that the condensate band has a peculiar structure called swallowtail when the periodic potential is shallow compared to the mean field energy. We find that the upper side of the swallowtail is dynamically unstable although the excitations have the linear dispersion reflecting the positive effective mass.Comment: 6 pages, 2 figures, Proceedings of the International Symposium on Quantum Fluids and Solids (QFS2006

Spin fluctuations in the quasi-two dimensional Heisenberg ferromagnet GdI_2 studied by Electron Spin Resonance

The spin dynamics of GdI_2 have been investigated by ESR spectroscopy. The temperature dependences of the resonance field and ESR intensity are well described by the model for the spin susceptibility proposed by Eremin et al. [Phys. Rev. B 64, 064425 (2001)]. The temperature dependence of the resonance linewidth shows a maximum similar to the electrical resistance and is discussed in terms of scattering processes between conduction electrons and localized spins.Comment: to be published in PR

System Design and Capabilities of a Current Technology, Low-Cost, Small Satellite

Ball Aerospace, with its successful background and strong interest in low-cost lightweight satellites, is studying the designs of current technology satellites for a variety of launchers (e.g., STS/GAS, Pershing, Scout, Poseidon, Conestoga, Titan 11, ILV, and Delta II). Ball Aerospace has completed the design of a current technology, multi-mission, low-cost Scout-compatible satellite. This paper summarizes the system design features and capabilities of this Ball Scout Satellite (BSS). The BSS is designed to accommodate a wide range of Earth and celestially oriented missions, both spinning and 3-axis stabilized. The BSS design provides a marked improvement in payload support capabilities (mass, power, data rate, pointing, interfaces, flexibility, reliability, etc.) than was previously available with earlier Scout satellites, and at a lower cost in current-year dollars

Darkness visible: reflections on underground ecology

1 Soil science and ecology have developed independently, making it difficult for ecologists to contribute to urgent current debates on the destruction of the global soil resource and its key role in the global carbon cycle. Soils are believed to be exceptionally biodiverse parts of ecosystems, a view confirmed by recent data from the UK Soil Biodiversity Programme at Sourhope, Scotland, where high diversity was a characteristic of small organisms, but not of larger ones. Explaining this difference requires knowledge that we currently lack about the basic biology and biogeography of micro-organisms. 2 It seems inherently plausible that the high levels of biological diversity in soil play some part in determining the ability of soils to undertake ecosystem-level processes, such as carbon and mineral cycling. However, we lack conceptual models to address this issue, and debate about the role of biodiversity in ecosystem processes has centred around the concept of functional redundancy, and has consequently been largely semantic. More precise construction of our experimental questions is needed to advance understanding. 3 These issues are well illustrated by the fungi that form arbuscular mycorrhizas, the Glomeromycota. This ancient symbiosis of plants and fungi is responsible for phosphate uptake in most land plants, and the phylum is generally held to be species-poor and non-specific, with most members readily colonizing any plant species. Molecular techniques have shown both those assumptions to be unsafe, raising questions about what factors have promoted diversification in these fungi. One source of this genetic diversity may be functional diversity. 4 Specificity of the mycorrhizal interaction between plants and fungi would have important ecosystem consequences. One example would be in the control of invasiveness in introduced plant species: surprisingly, naturalized plant species in Britain are disproportionately from mycorrhizal families, suggesting that these fungi may play a role in assisting invasion. 5 What emerges from an attempt to relate biodiversity and ecosystem processes in soil is our extraordinary ignorance about the organisms involved. There are fundamental questions that are now answerable with new techniques and sufficient will, such as how biodiverse are natural soils? Do microbes have biogeography? Are there rare or even endangered microbes

Pion-Muon Asymmetry Revisited

Long ago an unexpected and unexplainable phenomena was observed. The distribution of muons from positive pion decay at rest was anisotropic with an excess in the backward direction relative to the direction of the proton beam from which the pions were created. Although this effect was observed by several different groups with pions produced by different means, the result was not accepted by the physics community, because it is in direct conflict with a large set of other experiments indicating that the pion is a pseudoscalar particle. It is possible to satisfy both sets of experiments if helicity-zero vector particles exist and the pion is such a particle. Helicity-zero vector particles have direction but no net spin. For the neutral pion to be a vector particle requires an additional modification to conventional theory as discussed herein. An experiment is proposed which can prove that the asymmetry in the distribution of muons from pion decay is a genuine physical effect because the asymmetry can be modified in a controllable manner. A positive result will also prove that the pion is NOT a pseudoscalar particle.Comment: 9 pages, 3 figure