3,170 research outputs found

    The trend growth rate of employment : past, present, and future

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    Over the course of the recovery from the 2001 recession, many forecasters have revised downward their expectations for job growth in the United States. The often disappointing pace of employment growth has been attributed to various forces, such as the high health-care costs faced by employers, structural changes causing some industries to decline, outsourcing of jobs from the United States to other countries, and strong productivity growth. Many of these explanations imply the sluggish pace of job gains to be the result of weakness in aggregate demand and labor demand. However, some observers have suggested that broad demographic changes affecting labor supply – such as the aging of the population – could account for part of the sluggishness of job growth. The demographic changes may have slowed the trend growth rate of employment. A change in trend would have important implications for fiscal and monetary policy. For fiscal policy, slower trend growth in employment will tend to result in slower long-term growth in tax revenues, with potentially important effects on government programs such as Social Security. For monetary policy, assessments of the state of labor markets and the overall economy compared to sustainable trends often figure prominently in monetary policy decisions. If trend job growth were to slow, actual growth in jobs that appears weak by historical standards could exceed the new trend rate. The course of monetary policy could differ substantially if job growth were correctly realized to be above trend rather than incorrectly assessed to be at or below trend. Therefore, accurate assessments of potentially changing trends are important to effective monetary policy. Clark and Nakata examine employment and labor force indicators for evidence of a slowing of trend employment growth in the United States. They conclude that declines in the growth rates of population and labor force participation have caused the trend growth rate of employment to slow. Over the next ten years, a reasonable baseline projection for trend job growth is 1.1 percent per year, or about 120,000 jobs per month.Employment ; Labor market ; Unemployment

    A Formal, Resource Consumption-Preserving Translation of Actors to Haskell

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    We present a formal translation of an actor-based language with cooperative scheduling to the functional language Haskell. The translation is proven correct with respect to a formal semantics of the source language and a high-level operational semantics of the target, i.e. a subset of Haskell. The main correctness theorem is expressed in terms of a simulation relation between the operational semantics of actor programs and their translation. This allows us to then prove that the resource consumption is preserved over this translation, as we establish an equivalence of the cost of the original and Haskell-translated execution traces.Comment: Pre-proceedings paper presented at the 26th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2016), Edinburgh, Scotland UK, 6-8 September 2016 (arXiv:1608.02534

    Extended Quantum Dimer Model and novel valence-bond phases

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    We extend the quantum dimer model (QDM) introduced by Rokhsar and Kivelson so as to construct a concrete example of the model which exhibits the first-order phase transition between different valence-bond solids suggested recently by Batista and Trugman and look for the possibility of other exotic dimer states. We show that our model contains three exotic valence-bond phases (herringbone, checkerboard and dimer smectic) in the ground-state phase diagram and that it realizes the phase transition from the staggered valence-bond solid to the herringbone one. The checkerboard phase has four-fold rotational symmetry, while the dimer smectic, in the absence of quantum fluctuations, has massive degeneracy originating from partial ordering only in one of the two spatial directions. A resonance process involving three dimers resolves this massive degeneracy and dimer smectic gets ordered (order from disorder).Comment: 20 pages, 13 figures, accepted for publication in J. Stat. Mec

    <Advanced Energy Utilization Division> Biofunctional Chemistry Research Section

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    3-1. Research Activities in 202

    Global dynamics of a delayed SIRS epidemic model with a wide class of nonlinear incidence rates

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    In this paper, by constructing Lyapunov functionals, we consider the global dynamics of an SIRS epidemic model with a wide class of nonlinear incidence rates and distributed delays ∫ h 0 p(τ)f(S(t),I(t- τ))dτ under the condition that the total population converges to 1. By using a technical lemma which is derived from strong condition of strict monotonicity of functions f(S,I) and f(S,I)/I with respect to S≥0 and I&gt;0, we extend the global stability result for an SIR epidemic model if R 0&gt;1, where R 0 is the basic reproduction number. By using a limit system of the model, we also show that the disease-free equilibrium is globally asymptotically stable if R 0=1

    Stability analysis of delayed SIR epidemic models with a class of nonlinear incidence rates

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    We analyze stability of equilibria for a delayed SIR epidemic model, in which population growth is subject to logistic growth in absence of disease, with a nonlinear incidence rate satisfying suitable monotonicity conditions. The model admits a unique endemic equilibrium if and only if the basic reproduction number R 0 exceeds one, while the trivial equilibrium and the disease-free equilibrium always exist. First we show that the disease-free equilibrium is globally asymptotically stable if and only if R 0 ≤ 1. Second we show that the model is permanent if and only if R 0 &gt; 1. Moreover, using a threshold parameter R 0 characterized by the nonlinear incidence function, we establish that the endemic equilibrium is locally asymptotically stable for 1&lt; R0≤R 0 and it loses stability as the length of the delay increases past a critical value for 1&lt;R 0&lt; R0. Our result is an extension of the stability results in [J.-J. Wang, J.-Z. Zhang, Z. Jin, Analysis of an SIR model with bilinear incidence rate, Nonlinear Anal. RWA 11 (2009) 2390-2402]

    Chemo-Sensitive Running Droplet

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    Chemical control of the spontaneous motion of a reactive oil droplet moving on a glass substrate under an aqueous phase is reported. Experimental results show that the self-motion of an oil droplet is confined on an acid-treated glass surface. The transient behavior of oil-droplet motion is also observed with a high-speed video camera. A mathematical model that incorporates the effect of the glass surface charge is built based on the experimental observation of oil-droplet motion. A numerical simulation of this mathematical model reproduced the essential features concerning confinement within a certain chemical territory of oil-droplet motion, and also its transient behavior. Our results may shed light on physical aspects of reactive spreading and a chemotaxis in living things.Comment: 17 pages, 10 figure

    On the evolution and environmental dependence of the star formation rate versus stellar mass relation since z ˜ 2.

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    This paper discusses the evolution of the correlation between galaxy star formation rates (SFRs) and stellar mass (M*) over the last ∼10 Gyr, particularly focusing on its environmental dependence. We first present the mid-infrared (MIR) properties of the Hα-selected galaxies in a rich cluster Cl 0939+4713 at z = 0.4. We use wide-field Spitzer/MIPS 24 μm data to show that the optically red Hα emitters, which are most prevalent in group-scale environments, tend to have higher SFRs and higher dust extinction than the majority population of blue Hα sources. With an MIR stacking analysis, we find that the median SFR of Hα emitters is higher in higher density environment at z = 0.4. We also find that star-forming galaxies in high-density environment tend to have higher specific SFR (SSFR), although the trend is much less significant compared to that of SFR. This increase of SSFR in high-density environment is not visible when we consider the SFR derived from Hα alone, suggesting that the dust attenuation in galaxies depends on environment; galaxies in high-density environment tend to be dustier (by up to ∼0.5 mag), probably reflecting a higher fraction of nucleated, dusty starbursts in higher density environments at z = 0.4. We then discuss the environmental dependence of the SFR–M* relation for star-forming galaxies since z ∼ 2, by compiling our comparable, narrow-band-selected, large Hα emitter samples in both distant cluster environments and field environments. We find that the SSFR of Hα-selected galaxies (at the fixed mass of log (M*/M⊙) = 10) rapidly evolves as (1 + z)3, but the SFR–M* relation is independent of the environment since z ∼ 2, as far as we rely on the Hα-based SFRs (with M*-dependent extinction correction). Even if we consider the possible environmental variation in the dust attenuation, we conclude that the difference in the SFR–M* relation between cluster and field star-forming galaxies is always small (≲0.2 dex level) at any time in the history of the Universe since z ∼ 2

    Line nodes in the energy gap of high-temperature superconducting BaFe_2(As_{1-x}P_x)_2 from penetration depth and thermal conductivity measurements

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    We report magnetic penetration depth and thermal conductivity data for high-quality single crystals of BaFe2_2(As1x_{1-x}Px_{x})2_2 (Tc=30T_c=30\,K) which provide strong evidence that this material has line nodes in its energy gap. This is distinctly different from the nodeless gap found for (Ba,K)Fe2_2As2_2 which has similar TcT_c and phase diagram. Our results indicate that repulsive electronic interactions play an essential role for Fe-based high-TcT_c superconductivity but that uniquely there are distinctly different pairing states, with and without nodes, which have comparable TcT_c.Comment: 4 pages, 3 figures, revised version to be published in Phys. Rev. B Rapid Communicatio

    Incidence of childhood renal tumours: An international population-based study

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    Malignant renal tumours represent 5% of childhood cancers and include types with likely different aetiology: Wilms tumour (WT), rhabdoid renal tumour, kidney sarcomas and renal carcinomas. WT is the most common renal tumour in children, previously shown to vary internationally and with ethnicity. Using the comprehensive database of the International Incidence of Childhood Cancer study (IICC), we analysed global variations and time trends in incidence of renal tumour types in children (age 0‐14 years) and adolescents (age 15‐19 years). The results were presented by 14 world regions, and five ethnic groups in the United States. We included 15 320 renal tumours in children and 800 in adolescents reported to the 163 contributing registries during 2001‐2010. In children, age‐standardised incidence rate (ASR) of renal tumours was 8.3 per million (95% confidence interval, CI = 8.1, 8.4); it was the highest in North America and Europe (9‐10 per million) and the lowest in most Asian regions (4‐5 per million). In the United States, Blacks had the highest ASR (10.9 per million, 95% CI = 10.2, 11.6) and Asian and Pacific Islanders the lowest (4.4 per million, 95% CI = 3.6, 5.1). In adolescents, age‐specific incidence rate of renal tumours was 1.4 per million (95% CI = 1.3, 1.5). WT accounted for over 90% of all renal tumours in each age from 1 to 7 years and the proportion of renal carcinomas increased gradually with age. From 1996 to 2010, incidence remained mostly stable for WT (average annual percent change, AAPC = 0.1) and increased for renal carcinomas in children (AAPC = 3.7) and adolescents (AAPC = 3.2). Our findings warrant further monitoring
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