1,439 research outputs found

    Trace ideals for Fourier integral operators with non-smooth symbols II

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    We consider Fourier integral operators with symbols in modulation spaces and non-smooth phase functions whose second orders of derivatives belong to certain types of modulation space. We establish continuity and Schatten-von Neumann properties of such operators when acting on modulation spaces.Comment: 25 page

    Changes of variables in modulation and Wiener amalgam spaces

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    In this paper various properties of global and local changes of variables as well as properties of canonical transforms are investigated on modulation and Wiener amalgam spaces. We establish several relations among localisations of such spaces and, as a consequence, we obtain several versions of local and global Beurling–Helson type theorems. We also establish a number of positive results such as local boundedness of canonical transforms on modulation spaces, properties of homogeneous changes of variables, and local continuity of Fourier integral operators on equation image. Finally, counterparts of these results are discussed for spaces on the torus

    Susceptibility to apoptosis is differentially regulated by c-myc and mutated Ha-ras oncogenes and is associated with endonuclease availability.

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    Oncogenes and oncosuppressors can deregulate cell replication in tumours, and recently have been shown to influence the probability of apoptosis. The effects of human c-myc and mutated (T24) Ha-ras oncogenes on susceptibility to apoptosis were investigated by introducing them into immortalised rat fibroblasts. The resulting family of transfectants showed closely similar measures of proliferation, but widely divergent rates of apoptosis, differing by up to fifteen-fold, that correlated inversely with population expansion rates in vitro. T24-ras transfectants with moderate or high p21ras expression showed reduced apoptosis, and this was reversed by pharmacological inhibition of membrane localisation of p21ras by mevinolin. In contrast, c-myc stimulated apoptosis, and this was further enhanced by serum deprivation. Inducibility of effector proteins represents one possible mechanism of genetic control of the susceptibility to apoptosis, and its investigation showed that c-myc was associated with expression by viable cells of latent calcium/magnesium sensitive endonuclease activity characteristic of apoptosis. In contrast, endonuclease activity was not detected in viable cells of a T24-ras transfectant expressing high levels of p21ras. Thus, there appeared to be differential regulation of susceptibility to apoptosis, positively by c-myc and negatively by activated ras, and this was associated with availability of endonuclease activity. Genetic modulation of apoptosis in human neoplasms is likely to influence net growth rate, retention of cells acquiring new mutations and response to certain chemotherapeutic agents

    Evaluation of the potential use of risk-based sampling to surveillance of antibacterial residues in Danish pork

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    Consumers consider presence of chemical substances in food products as undesirable. In Denmark, more than 20,000 samples are analysed each year for presence of antibacterial residues in Danish slaughter pigs, and these surveillance data indicate that the true antibacterial residue prevalence in Danish slaughter pigs is negligible. The question has been raised whether it would be possible to improve the cost-effectiveness of the surveillance programme. This was addressed in this study

    Phonon-induced quadrupolar ordering of the magnetic superconductor TmNi2_2B2_2C

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    We present synchrotron x-ray diffraction studies revealing that the lattice of thulium borocarbide is distorted below T_Q = 13.5 K at zero field. T_Q increases and the amplitude of the displacements is drastically enhanced, by a factor of 10 at 60 kOe, when a magnetic field is applied along [100]. The distortion occurs at the same wave vector as the antiferromagnetic ordering induced by the a-axis field. A model is presented that accounts for the properties of the quadrupolar phase and explains the peculiar behavior of the antiferromagnetic ordering previously observed in this compound.Comment: submitted to PR

    Adiabaticity Conditions for Volatility Smile in Black-Scholes Pricing Model

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    Our derivation of the distribution function for future returns is based on the risk neutral approach which gives a functional dependence for the European call (put) option price, C(K), given the strike price, K, and the distribution function of the returns. We derive this distribution function using for C(K) a Black-Scholes (BS) expression with volatility in the form of a volatility smile. We show that this approach based on a volatility smile leads to relative minima for the distribution function ("bad" probabilities) never observed in real data and, in the worst cases, negative probabilities. We show that these undesirable effects can be eliminated by requiring "adiabatic" conditions on the volatility smile

    Review: Attachment and attachment-related outcomes in preschool children – a review of recent evidence

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    Background Secure attachment is associated with optimal outcomes across all domains in childhood, and both insecure and disorganised attachment are associated with a range of later psychopathologies. Insecure and disorganised attachment are common, particularly in disadvantaged populations, pointing to the need to identify effective methods of addressing such problems. Aims This paper presents the findings of a review of secondary and primary studies evaluating the effectiveness of interventions aimed at improving attachment and attachment-related outcomes on a universal, targeted or indicated basis, which was undertaken as part of an update of the evidence base for a UK-based national programme targeting children aged 0–5 years (Healthy Child Programme). Method A systematic search of key electronic databases was undertaken to identify secondary and primary sources of data that addressed the research question and that had been published between 2008 and 2014; search sources included Cochrane Collaboration, NICE, EPPI Centre, Campbell Collaboration and PubMed, PsychInfo, CINAHL databases. Findings Six systematic reviews and 11 randomised controlled trials were identified that had evaluated the effectiveness of universal, selective or indicated interventions aimed at improving attachment and attachment-related outcomes in children aged 0–5 years. Potentially effective methods of improving infant attachment include parent–infant psychotherapy, video feedback and mentalisation-based programmes. Methods that appear to be effective in improving attachment-related outcomes include home visiting and parenting programmes. Conclusions A number of methods of working to promote attachment and attachment-related outcomes in preschool children are now being recommended as part of the Healthy Child Programme. The implications in terms of the role and contribution of practitioners working in child and adolescent mental health service are discusse

    A Turnover in the Galaxy Main Sequence of Star Formation at M1010MM_{*} \sim 10^{10} M_{\odot} for Redshifts z<1.3z < 1.3

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    The relationship between galaxy star formation rates (SFR) and stellar masses (MM_\ast) is re-examined using a mass-selected sample of \sim62,000 star-forming galaxies at z1.3z \le 1.3 in the COSMOS 2-deg2^2 field. Using new far-infrared photometry from HerschelHerschel-PACS and SPIRE and SpitzerSpitzer-MIPS 24 μ\mum, along with derived infrared luminosities from the NRK method based on galaxies' locations in the restframe color-color diagram (NUVr)(NUV - r) vs. (rK)(r - K), we are able to more accurately determine total SFRs for our complete sample. At all redshifts, the relationship between median SFRSFR and MM_\ast follows a power-law at low stellar masses, and flattens to nearly constant SFR at high stellar masses. We describe a new parameterization that provides the best fit to the main sequence and characterizes the low mass power-law slope, turnover mass, and overall scaling. The turnover in the main sequence occurs at a characteristic mass of about M01010MM_{0} \sim 10^{10} M_{\odot} at all redshifts. The low mass power-law slope ranges from 0.9-1.3 and the overall scaling rises in SFR as a function of (1+z)4.12±0.10(1+z)^{4.12 \pm 0.10}. A broken power-law fit below and above the turnover mass gives relationships of SFRM0.88±0.06SFR \propto M_{*}^{0.88 \pm 0.06} below the turnover mass and SFRM0.27±0.04SFR \propto M_{*}^{0.27 \pm 0.04} above the turnover mass. Galaxies more massive than M1010 MM_\ast \gtrsim 10^{10}\ M_{\rm \odot} have on average, a much lower specific star formation rate (sSFR) than would be expected by simply extrapolating the traditional linear fit to the main sequence found for less massive galaxies.Comment: 16 pages, 7 figures. Accepted for publication in Ap

    The Space Density and Colors of Massive Galaxies at 2<z<3: the Predominance of Distant Red Galaxies

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    Using the deep multi-wavelength MUSYC, GOODS, and FIRES surveys we construct a stellar mass-limited sample of galaxies at 2<z<3. The sample comprises 294 galaxies with M>10^11 Solar masses distributed over four independent fields with a total area of almost 400 sq arcmin. The mean number density of massive galaxies in this redshift range is (2.2+-0.6) x 10^-4 Mpc^-3. We present median values and 25th and 75th percentiles for the distributions of observed R mags, observed J-K colors, and rest-frame UV continuum slopes, M/L(V) ratios, and U-V colors. The galaxies show a large range in all these properties. The ``median galaxy'' is faint in the observer's optical (R=25.9), red in the observed near-IR (J-K=2.48), has a rest-frame UV spectrum which is relatively flat (beta=-0.4), and rest-frame optical colors resembling those of nearby spiral galaxies (U-V=0.62). We determine which galaxies would be selected as Lyman break galaxies (LBGs) or Distant Red Galaxies (DRGs, having J-K>2.3) in this mass-limited sample. By number DRGs make up 69% of the sample and LBGs 20%, with a small amount of overlap. By mass DRGs make up 77% and LBGs 17%. Neither technique provides a representative sample of massive galaxies at 2<z<3 as they only sample the extremes of the population. As we show here, multi-wavelength surveys with high quality photometry are essential for an unbiased census of massive galaxies in the early Universe. The main uncertainty in this analysis is our reliance on photometric redshifts; confirmation of the results presented here requires extensive near-infrared spectroscopy of optically-faint samples.Comment: Accepted for publication in ApJ Letter

    High resolution observations and mass modelling of the CLASS gravitational lens B1152+199

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    We present a series of high resolution radio and optical observations of the CLASS gravitational lens system B1152+199 obtained with the Multi-Element Radio-Linked Interferometer Network (MERLIN), Very Long Baseline Array (VLBA) and Hubble Space Telescope (HST). Based on the milliarcsecond-scale substructure of the lensed radio components and precise optical astrometry for the lensing galaxy, we construct models for the system and place constraints on the galaxy mass profile. For a single galaxy model with surface mass density Sigma(r) propto r^-beta, we find that 0.95 < beta < 1.21 at 2-sigma confidence. Including a second deflector to represent a possible satellite galaxy of the primary lens leads to slightly steeper mass profiles.Comment: 7 pages, post-referee revision for MNRA
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