2,237 research outputs found

    Addiction through the Ages: a review of the development of concepts and ideas about addiction in European countries since the nineteenth century and the role of international organisations in the process

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    The work on addiction through the ages proceeded through 4 interlinked studies: The emergence of concepts of addiction across Europe at the national level, 1860-1980 The framing of the alcohol question at the international alcohol conferences The role of the World Health Organisation (WHO) and its expert committees in defining addiction from the 1940s to the early twenty first century The role of the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) in defining concepts of addiction The long view of addiction concepts at the country level over time points to continuities and changes across countries. They have also played a significant role in international organisations, the pre World War Two alcohol conferences and the World Health Organisation (WHO) after that war. The European level through the European Monitoring Centre on Drugs and Drug Addiction has also come into the picture in more recent times with discussion of a different set of concepts. Although a degree of stability has been achieved around addiction concepts, these still encapsulate a variety of meanings which translate into different treatment and policy approaches and traditions within Europe. By understanding the history of such concepts and how and why they came in and out of use, we can better understand addiction terminology and substance use policy today

    Inter-Intra Molecular Dynamics as an Iterated Function System

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    The dynamics of units (molecules) with slowly relaxing internal states is studied as an iterated function system (IFS) for the situation common in e.g. biological systems where these units are subjected to frequent collisional interactions. It is found that an increase in the collision frequency leads to successive discrete states that can be analyzed as partial steps to form a Cantor set. By considering the interactions among the units, a self-consistent IFS is derived, which leads to the formation and stabilization of multiple such discrete states. The relevance of the results to dynamical multiple states in biomolecules in crowded conditions is discussed.Comment: 7 pages, 7 figures. submitted to Europhysics Letter

    Exploring the links between star formation and minor companions around isolated galaxies

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    Previous studies have shown that galaxies with minor companions exhibit an elevated star formation rate. We reverse this inquiry, constructing a volume-limited sample of \simL\star (Mr \leq -19.5 + 5 log h) galaxies from the Sloan Digital Sky Survey that are isolated with respect to other luminous galaxies. Cosmological simulations suggest that 99.8% of these galaxies are alone in their dark matter haloes with respect to other luminous galaxies. We search the area around these galaxies for photometric companions. Matching strongly star forming (EW(H{\alpha})\geq 35 \AA) and quiescent (EW(H{\alpha})< 35 \AA) samples for stellar mass and redshift using a Monte Carlo resampling technique, we demonstrate that rapidly star-forming galaxies are more likely to have photometric companions than other galaxies. The effect is relatively small; about 11% of quiescent, isolated galaxies have minor photometric companions at radii \leq 60 kpc h1^{-1} kpc while about 16% of strongly star-forming ones do. Though small, the cumulative difference in satellite counts between strongly star-forming and quiescent galaxies is highly statistically significant (PKS = 1.350 \times103^{-3}) out to to radii of \sim 100 h1^{-1} kpc. We discuss explanations for this excess, including the possibility that \sim 5% of strongly star-forming galaxies have star formation that is causally related to the presence of a minor companion.Comment: 7 pages, 6 figures, submitted to MNRA

    Correctly validating results from single molecule data: the case of stretched exponential decay in the catalytic activity of single lipase B molecules

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    The question of how to validate and interpret correctly the waiting time probability density functions (WT-PDFs) from single molecule data is addressed. It is shown by simulation that when a stretched exponential WT-PDF, with a stretched exponent alfa and a time scale parameter tau, generates the off periods of a two-state trajectory, a reliable recovery of the input WT-PDF from the trajectory is obtained even when the bin size used to define the trajectory, dt, is much larger than the parameter tau. This holds true as long as the first moment of the WT-PDF is much larger than dt. Our results validate the results in an earlier study of the activity of single Lipase B molecules and disprove recent related critique

    Synchronization of active mechanical oscillators by an inertial load

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    Motivated by the operation of myogenic (self-oscillatory) insect flight muscle, we study a model consisting of a large number of identical oscillatory contractile elements joined in a chain, whose end is attached to a damped mass-spring oscillator. When the inertial load is small, the serial coupling favors an antisynchronous state in which the extension of one oscillator is compensated by the contraction of another, in order to preserve the total length. However, a sufficiently massive load can sychronize the oscillators and can even induce oscillation in situations where isolated elements would be stable. The system has a complex phase diagram displaying quiescent, synchronous and antisynchrononous phases, as well as an unsual asynchronous phase in which the total length of the chain oscillates at a different frequency from the individual active elements.Comment: 5 pages, 4 figures, To appear in Phys. Rev. Let

    Genomic analysis of four strains of Corynebacterium pseudotuberculosis bv. Equi isolated from horses showing distinct signs of infection.

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    The genomes of four strains (MB11, MB14, MB30, and MB66) of the species Corynebacterium pseudotuberculosis biovar equi were sequenced on the Ion Torrent PGM platform, completely assembled, and their gene content and structure were analyzed. The strains were isolated from horses with distinct signs of infection, including ulcerative lymphangitis, external abscesses on the chest, or internal abscesses on the liver, kidneys, and lungs. The average size of the genomes was 2.3 Mbp, with 2169 (Strain MB11) to 2235 (Strain MB14) predicted coding sequences (CDSs). An optical map of the MB11 strain generated using the KpnI restriction enzyme showed that the approach used to assemble the genome was satisfactory, producing good alignment between the sequence observed in vitro and that obtained in silico. In the resulting Neighbor-Joining dendrogram, the C. pseudotuberculosis strains sequenced in this study were clustered into a single clade supported by a high bootstrap value. The structural analysis showed that the genomes of the MB11 and MB14 strains were very similar, while the MB30 and MB66 strains had several inverted regions. The observed genomic characteristics were similar to those described for other strains of the same species, despite the number of inversions found. These genomes will serve as a basis for determining the relationship between the genotype of the pathogen and the type of infection that it causes

    Structural dynamics of a metal-organic framework induced by CO2 migration in its non-uniform porous structure

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    Stimuli-responsive behaviors of flexible metal-organic frameworks (MOFs) make these materials promising in a wide variety of applications such as gas separation, drug delivery, and molecular sensing. Considerable efforts have been made over the last decade to understand the structural changes of flexible MOFs in response to external stimuli. Uniform pore deformation has been used as the general description. However, recent advances in synthesizing MOFs with non-uniform porous structures, i.e. with multiple types of pores which vary in size, shape, and environment, challenge the adequacy of this description. Here, we demonstrate that the CO -adsorption-stimulated structural change of a flexible MOF, ZIF-7, is induced by CO migration in its non-uniform porous structure rather than by the proactive opening of one type of its guest-hosting pores. Structural dynamics induced by guest migration in non-uniform porous structures is rare among the enormous number of MOFs discovered and detailed characterization is very limited in the literature. The concept presented in this work provides new insights into MOF flexibility

    Genome Sequence of Corynebacterium pseudotuberculosis MB20 bv. equi Isolated from a Pectoral Abscess of an Oldenburg Horse in California.

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    The genome of Corynebacterium pseudotuberculosis MB20 bv. equi was sequenced using the Ion Personal Genome Machine (PGM) platform, and showed a size of 2,363,089 bp, with 2,365 coding sequences and a GC content of 52.1%. These results will serve as a basis for further studies on the pathogenicity of C. pseudotuberculosis bv. equi

    Force and Motion Generation of Molecular Motors: A Generic Description

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    We review the properties of biological motor proteins which move along linear filaments that are polar and periodic. The physics of the operation of such motors can be described by simple stochastic models which are coupled to a chemical reaction. We analyze the essential features of force and motion generation and discuss the general properties of single motors in the framework of two-state models. Systems which contain large numbers of motors such as muscles and flagella motivate the study of many interacting motors within the framework of simple models. In this case, collective effects can lead to new types of behaviors such as dynamic instabilities of the steady states and oscillatory motion.Comment: 29 pages, 9 figure
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