1,120 research outputs found

    Time separation as a hidden variable to the Copenhagen school of quantum mechanics

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    The Bohr radius is a space-like separation between the proton and electron in the hydrogen atom. According to the Copenhagen school of quantum mechanics, the proton is sitting in the absolute Lorentz frame. If this hydrogen atom is observed from a different Lorentz frame, there is a time-like separation linearly mixed with the Bohr radius. Indeed, the time-separation is one of the essential variables in high-energy hadronic physics where the hadron is a bound state of the quarks, while thoroughly hidden in the present form of quantum mechanics. It will be concluded that this variable is hidden in Feynman's rest of the universe. It is noted first that Feynman's Lorentz-invariant differential equation for the bound-state quarks has a set of solutions which describe all essential features of hadronic physics. These solutions explicitly depend on the time separation between the quarks. This set also forms the mathematical basis for two-mode squeezed states in quantum optics, where both photons are observable, but one of them can be treated a variable hidden in the rest of the universe. The physics of this two-mode state can then be translated into the time-separation variable in the quark model. As in the case of the un-observed photon, the hidden time-separation variable manifests itself as an increase in entropy and uncertainty.Comment: LaTex 10 pages with 5 figure. Invited paper presented at the Conference on Advances in Quantum Theory (Vaxjo, Sweden, June 2010), to be published in one of the AIP Conference Proceedings serie

    Quantification of the response of circulating epithelial cells to neodadjuvant treatment for breast cancer: a new tool for therapy monitoring

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    INTRODUCTION: In adjuvant treatment for breast cancer there is no tool available with which to measure the efficacy of the therapy. In contrast, in neoadjuvant therapy reduction in tumour size is used as an indicator of the sensitivity of tumour cells to the agents applied. If circulating epithelial (tumour) cells can be shown to react to therapy in the same way as the primary tumour, then this response may be exploited to monitor the effect of therapy in the adjuvant setting. METHOD: We used MAINTRAC(® )analysis to monitor the reduction in circulating epithelial cells during the first three to four cycles of neoadjuvant therapy in 30 breast cancer patients. RESULTS: MAINTRAC(® )analysis revealed a patient-specific response. Comparison of this response with the decline in size of the primary tumour showed that the reduction in number of circulating epithelial cells accurately predicted final tumour reduction at surgery if the entire neoadjuvant regimen consisted of chemotherapy. However, the response of the circulating tumour cells was unable to predict the response to additional antibody therapy. CONCLUSION: The response of circulating epithelial cells faithfully reflects the response of the whole tumour to adjuvant therapy, indicating that these cells may be considered part of the tumour and can be used for therapy monitoring

    Mineral chemistry of igneous melanite garnets from analcite-bearing volcanic rocks, Alberta, Canada

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    The mineral chemistry of melanite garnets from the Crowsnest volcanic rocks of SW Alberta, Canada, has been investigated by using electron microprobe scans, quantitative analyses and multivariate statistical analysis. The garnets occur with aegirine-augite, sanidine, analcite and rare plagioclase as phenocrysts in trachyte and phonolite flows, agglomerates and tuffs. Wavelength dispersive microprobe scans reveal complex zonation patterns, both normal and oscillatory. The results of fifty quantitative analyses were subjected to R-mode factor analysis to delineate the chemical exchanges producing the zonation. The chemical zonation of the garnets may be attributed to four independent binary exchanges; Al-Fe3+, Si-Ti, Ca-Mn and Mg-Fe2+. The stoichiometry of these garnets, based on microprobe and wet chemical Fe analyses, combined with the strongly antithetic behavior of Si and Ti lead us to infer that the Ti in these garnets is dominantly tetravalent. It is clear from this study that quantitative modelling of the processes of crystal growth and zonation of melanite garnets in alkaline, undersaturated igneous rocks should be aimed at simulating the four chemical exchanges listed above

    Potential role of levocarnitine supplementation for the treatment of chemotherapy-induced fatigue in non-anaemic cancer patients

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    Ifosfamide and cisplatin cause urinary loss of carnitine, which is a fundamental molecule for energy production in mammalian cells. We investigated whether restoration of the carnitine pool might improve chemotherapy-induced fatigue in non-anaemic cancer patients. Consecutive patients with low plasma carnitine levels who experienced fatigue during chemotherapy were considered eligible for study entry. Patients were excluded if they had anaemia or other conditions thought to be causing asthenia. Fatigue was assessed by the Functional Assessment of Cancer Therapy-Fatigue quality of life questionnaire. Treatment consisted of oral levocarnitine 4 g daily, for 7 days. Fifty patients were enrolled; chemotherapy was cisplatin-based in 44 patients and ifosfamide-based in six patients. In the whole group, baseline mean Functional Assessment of Cancer Therapy-Fatigue score was 19.7 (±6.4; standard deviation) and the mean plasma carnitine value was 20.9 μM (±6.8; standard deviation). After 1 week, fatigue ameliorated in 45 patients and the mean Functional Assessment of Cancer Therapy-Fatigue score was 34.9 (±5.4; standard deviation) (P<.001). All patients achieved normal plasma carnitine levels. Patients maintained the improved Functional Assessment of Cancer Therapy-Fatigue score until the next cycle of chemotherapy. In selected patients, levocarnitine supplementation may be effective in alleviating chemotherapy-induced fatigue. This compound deserves further investigations in a randomised, placebo-controlled study

    Cortical Surround Interactions and Perceptual Salience via Natural Scene Statistics

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    Spatial context in images induces perceptual phenomena associated with salience and modulates the responses of neurons in primary visual cortex (V1). However, the computational and ecological principles underlying contextual effects are incompletely understood. We introduce a model of natural images that includes grouping and segmentation of neighboring features based on their joint statistics, and we interpret the firing rates of V1 neurons as performing optimal recognition in this model. We show that this leads to a substantial generalization of divisive normalization, a computation that is ubiquitous in many neural areas and systems. A main novelty in our model is that the influence of the context on a target stimulus is determined by their degree of statistical dependence. We optimized the parameters of the model on natural image patches, and then simulated neural and perceptual responses on stimuli used in classical experiments. The model reproduces some rich and complex response patterns observed in V1, such as the contrast dependence, orientation tuning and spatial asymmetry of surround suppression, while also allowing for surround facilitation under conditions of weak stimulation. It also mimics the perceptual salience produced by simple displays, and leads to readily testable predictions. Our results provide a principled account of orientation-based contextual modulation in early vision and its sensitivity to the homogeneity and spatial arrangement of inputs, and lends statistical support to the theory that V1 computes visual salience

    Axillary sentinel lymph node biopsy after mastectomy: a case report

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    <p>Abstract</p> <p>Background</p> <p>Sentinel lymph node biopsy has been established as the preferred method for staging early breast cancer. A prior history of mastectomy is felt to be a contraindication.</p> <p>Case presentation</p> <p>A patient with recurrent breast cancer in her skin flap was discovered to have positive axillary sentinel nodes by sentinel lymph node biopsy five years after mastectomy for ductal carcinoma in situ.</p> <p>Conclusion</p> <p>A prior history of mastectomy may not be an absolute contraindication to sentinel lymph node biopsy.</p

    A comprehensive 1000 Genomes-based genome-wide association meta-analysis of coronary artery disease

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    Existing knowledge of genetic variants affecting risk of coronary artery disease (CAD) is largely based on genome-wide association studies (GWAS) analysis of common SNPs. Leveraging phased haplotypes from the 1000 Genomes Project, we report a GWAS meta-analysis of 185 thousand CAD cases and controls, interrogating 6.7 million common (MAF>0.05) as well as 2.7 million low frequency (0.005<MAF<0.05) variants. In addition to confirmation of most known CAD loci, we identified 10 novel loci, eight additive and two recessive, that contain candidate genes that newly implicate biological processes in vessel walls. We observed intra-locus allelic heterogeneity but little evidence of low frequency variants with larger effects and no evidence of synthetic association. Our analysis provides a comprehensive survey of the fine genetic architecture of CAD showing that genetic susceptibility to this common disease is largely determined by common SNPs of small effect siz

    Topical rapamycin inhibits tuberous sclerosis tumor growth in a nude mouse model

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    <p>Abstract</p> <p>Background</p> <p>Skin manifestations of Tuberous Sclerosis Complex (TSC) cause significant morbidity. The molecular mechanism underlying TSC is understood and there is evidence that systemic treatment with rapamycin or other mTOR inhibitors may be a useful approach to targeted therapy for the kidney and brain manifestations. Here we investigate topical rapamycin in a mouse model for TSC-related tumors.</p> <p>Methods</p> <p>0.4% and 0.8% rapamycin ointments were applied to nude mice bearing subcutaneous, TSC-related tumors. Topical treatments were compared with injected rapamycin and topical vehicle. Rapamycin levels in blood and tumors were measured to assess systemic drug levels in all cohorts.</p> <p>Results</p> <p>Treatment with topical rapamycin improved survival and reduced tumor growth. Topical rapamycin treatment resulted in systemic drug levels within the known therapeutic range and was not as effective as injected rapamycin.</p> <p>Conclusion</p> <p>Topical rapamycin inhibits TSC-related tumor growth. These findings could lead to a novel treatment approach for facial angiofibromas and other TSC skin lesions.</p
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