12,058 research outputs found

    The Mass Shell of the Nelson Model without Cut-Offs

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    The massless Nelson model describes non-relativistic, spinless quantum particles interacting with a relativistic, massless, scalar quantum field. The interaction is linear in the field. We analyze the one particle sector. First, we construct the renormalized mass shell of the non-relativistic particle for an arbitrarily small infrared cut-off that turns off the interaction with the low energy modes of the field. No ultraviolet cut-off is imposed. Second, we implement a suitable Bogolyubov transformation of the Hamiltonian in the infrared regime. This transformation depends on the total momentum of the system and is non-unitary as the infrared cut-off is removed. For the transformed Hamiltonian we construct the mass shell in the limit where both the ultraviolet and the infrared cut-off are removed. Our approach is constructive and leads to explicit expansion formulae which are amenable to rigorously control the S-matrix elements.Comment: explanations added, typos correcte

    Just war and military morale: a brief reflection on the correlation between the legality of war and the moral repercussions for members of US and UK forces arising from the questionable legality of the campaign Iraqi Freedom of March 2003

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    Does it matter to a member of the military whether the military campaign in which he is taking part is lawful or not? Despite the observation that the crime of aggression (post Kampala 2010) constitutes a ‘leadership crime par excellence,’ which limits any (future) criminal responsibility accordingly, the legality or illegality of any military action under international law can create moral implications for the common foot soldier and mid-level officer and also have a tangible impact on the national legal frameworks under which these forces operate. This short article uses the example of Operation Iraqi Freedom (2003) to discuss the repercussions of a—most likely—illegal military campaign for individual members of democratic armed forces before the background of the present discussion of NATO led action in Libya

    Comparing Growth Trajectories of Risk Behaviors From Late Adolescence Through Young Adulthood: An Accelerated Design.

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    Risk behaviors such as substance use or deviance are often limited to the early stages of the life course. Whereas the onset of risk behavior is well studied, less is currently known about the decline and timing of cessation of risk behaviors of different domains during young adulthood. Prevalence and longitudinal developmental patterning of alcohol use, drinking to the point of drunkenness, smoking, cannabis use, deviance, and HIV-related sexual risk behavior were compared in a Swiss community sample (N = 2,843). Using a longitudinal cohort-sequential approach to link multiple assessments with 3 waves of data for each individual, the studied period spanned the ages of 16 to 29 years. Although smoking had a higher prevalence, both smoking and drinking up to the point of drunkenness followed an inverted U-shaped curve. Alcohol consumption was also best described by a quadratic model, though largely stable at a high level through the late 20s. Sexual risk behavior increased slowly from age 16 to age 22 and then remained largely stable. In contrast, cannabis use and deviance linearly declined from age 16 to age 29. Young men were at higher risk for all behaviors than were young women, but apart from deviance, patterning over time was similar for both sexes. Results about the timing of increase and decline as well as differences between risk behaviors may inform tailored prevention programs during the transition from late adolescence to adulthood

    The role of polyamines in human cancer: prospects for drug combination therapies.

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    Ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC) are two key enzymes in polyamine (PA) biosynthesis and their inhibition leads to PA pool depletion and cell growth arrest. DFMO and SAM486A are specific inhibitors of ODC and AdoMetDC, respectively, and are the only two PA inhibitors, which have been clinically evaluated in Phase II and III cancer trials. However, drug combination therapies expected to potentiate the effects of these drugs have yet to be systematically pursued. Human cancer trials (e.g. for the treatment of neuroblastoma patients) using a DFMO/SAM486A cocktail, possibly combined with current cytotoxic drugs and concomitant with a PA-deficient diet, are warranted

    Generalized Jacobi-Trudi determinants and evaluations of Schur multiple zeta values

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    We present new determinant expressions for regularized Schur multiple zeta values. These generalize the known Jacobi–Trudi formulas and can be used to quickly evaluate certain types of Schur multiple zeta values. Using these formulas we prove that every Schur multiple zeta value with alternating entries in 1 and 3 can be written as a polynomial in Riemann zeta values. Furthermore, we give conditions on the shape, which determine when such Schur multiple zetas are polynomials purely in odd or in even Riemann zeta values

    Conformational Mechanics of Polymer Adsorption Transitions at Attractive Substrates

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    Conformational phases of a semiflexible off-lattice homopolymer model near an attractive substrate are investigated by means of multicanonical computer simulations. In our polymer-substrate model, nonbonded pairs of monomers as well as monomers and the substrate interact via attractive van der Waals forces. To characterize conformational phases of this hybrid system, we analyze thermal fluctuations of energetic and structural quantities, as well as adequate docking parameters. Introducing a solvent parameter related to the strength of the surface attraction, we construct and discuss the solubility-temperature phase diagram. Apart from the main phases of adsorbed and desorbed conformations, we identify several other phase transitions such as the freezing transition between energy-dominated crystalline low-temperature structures and globular entropy-dominated conformations.Comment: 13 pages, 15 figure

    Killing two birds with one drug: a new application for HIV-1 cell entry inhibitors in the treatment of metastatic cancer.

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    The chemokine receptors CCR5 and CXCR4 serve as co-receptors for the human immunodeficiency virus 1 (HIV-1) and thus, are important cellular components during HIV-1 cell entry. In recent years, a new biological role for chemokine receptors has emerged in assisting the spread of primary tumors to distant secondary sites within the human body (metastasis). This review highlights some of the HIV-1 cell entry inhibitors (antagonists), which are currently in development and/or under evaluation in clinical trials, and discusses the therapeutic use of these new antagonists for the treatment of certain forms of metastatic cancer
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