Determinacy of Equilibrium Under Various Phillips Curves

Determinacy of equilibrium under the original, the backward-looking, the forward-looking and the hybrid Phillips curves is examined. If the monetary authority keeps the nominal money stock to be constant, the equilibrium path is always determinate under the original Phillips curve and the forward-looking one. Under the backward-looking one and the hybrid one, however, the path can be non-existent. The case of a Taylor rule is also examined. Under any of the four curves the path is always determinate if the monetary policy is active but is never determinate if it is passive

A Locally Smoothed Terrain-Following Vertical Coordinate to Improve the Simulation of Fog and Low Stratus in Numerical Weather Prediction Models

The correct simulation of fog and low stratus (FLS) is a difficult task for numerical weather prediction (NWP) models. The Swiss Plateau experiences many days with FLS in winter. Most NWP models employ terrain-following vertical coordinates. As a consequence, the typically flat cloud top is intersected by sloping coordinate surfaces above hilly terrain such as the Swiss Plateau. Horizontal advection across the sloping coordinate surfaces leads to spurious numerical diffusion which promotes erroneous FLS dissipation. To address this problem, we propose a new vertical coordinate formulation which features a local smoothing of the model levels. We demonstrate the positive impact of the new vertical coordinate formulation on a case study in detail and for a full month using the COSMO model. The improved vertical coordinate formulation is not yet sufficient to obtain perfect FLS forecasts, it is however a crucial aspect to consider on the way thereto.ISSN:1942-246

Data and scripts for the submission "A locally smoothed terrain-following vertical coordinate to improve the simulation of fog and low stratus in numerical weather prediction models"

<p>Dataset and scripts used to generate Figures for "A locally smoothed terrain-following vertical coordinate to improve the simulation of fog and low stratus in numerical weather prediction models", submitted to the <strong><em>Journal of Advances in Modeling Earth Systems</em></strong> (JAMES).</p> <p>Scripts: Python and NCL</p> <p>Data: Netcdf, PNG, Python pickled objects</p><p>added file const_sleve.nc</p&gt

Identifying the key challenges for fog and low stratus forecasting in complex terrain

Forecasting fog and low stratus (FLS) accurately poses a challenge to current numerical weather prediction models, despite many advancements in recent years. We present a novel method to quantify FLS extent bias by comparing forecasts with satellite observations. Evaluating a four-month period, we show that COSMO-1, the MeteoSwiss high-resolution operational model, exhibits a considerable negative FLS bias during wintertime. To study the cause, we conduct a series of sensitivity experiments for a representative case study, where COSMO-1 dissipated extensive FLS erroneously. Replacing the one-moment bulk microphysics parameterisation scheme by a two-moment scheme, as well as increasing the number of vertical levels, did not show any improvements. The FLS dissipation was delayed (but not prevented) by decreasing the lower bound imposed on the turbulent diffusion coefficients from 0.4 to 0.01 m(2)center dot s(-1), or by reducing horizontal grid spacing from 1.1 km to 550 m. Additionally, simulations at 1.1-km grid spacing with smoothed orography led to more extensive FLS than the same simulations without smoothed orography. An analysis of the cloud water budget revealed that the model's advection scheme is causing a loss of liquid water content near the cloud top. A simulation with an alternative terrain-following coordinate system, in which the vertical coordinates are quasihorizontal near the cloud top, reduced the loss of cloud water through advection and improved the evolution of FLS in the case study. In combination, our findings suggest that the advection scheme exhibits numerical diffusion, which promotes spurious mixing in the vertical of cloudy and adjacent cloud-free grid cells in terrain-following vertical coordinates; this process can become the root cause for too rapid dissipation of FLS during nighttime in complex terrain.ISSN:0035-9009ISSN:1477-870

Effects of terrain-following vertical coordinates on simulation of stratus clouds in numerical weather prediction models

Many numerical weather prediction models employ terrain-following vertical coordinates. As a consequence, over orography, flat tops of stratus clouds are intersected by the vertical coordinate surfaces. We conduct idealised two-dimensional simulations of a stratus cloud with the COSMO model to study the effect of such sloping vertical coordinate surfaces. The evolution of the stratus cloud above a flat surface within a horizontally homogeneous atmosphere serves as a reference. During night-time, the cloud thickens, driven by radiative cooling at the cloud top. Adding a sinusoidal perturbation to the vertical coordinate surfaces reduces the growth of the stratus cloud. With strong perturbations, the cloud starts to dissipate. The physical processes in the two simulations are identical, hence this behaviour is purely driven by numerical diffusion. The cloud is similarly thinned when sinusoidal orographic features are introduced. The reduction depends on the amplitude and wavelength of the perturbations and hills. Increasing the horizontal resolution partly mitigates the numerical diffusion. However, this is a very costly measure for an operational weather model. We suggest conducting further research on a new vertical coordinate with additional local smoothing of the orographic signal.ISSN:0035-9009ISSN:1477-870

Maternal microbiota and antibodies as advocates of neonatal health

Mammalian body surfaces are inhabited by vast numbers of microbes, the commensal microbiota, which help the host to digest food, provide nutrients, and mature its immune system. For a long time, postnatal colonization was believed to be the main stimulus for microbial-induced immune development. Using a model of reversible colonization of germ-free mice during gestation, we recently showed that the microbial shaping of the neonatal immune system begins even before birth through molecular signals derived from the microbiota of the mother. Maternal microbiota was important to mature intestinal innate immune cells and to alter intestinal gene expression profiles in the offspring. These changes prepare the newborn for postnatal colonization. The majority of the gestational colonization-dependent effects required maternal antibodies. Here, we discuss and provide further evidence how maternal antibodies are important players in transferring a signal originating from the maternal intestinal microbiota to the offspring.ISSN:1949-0976ISSN:1949-098

Nanocomposites of high-density polyethylene with amorphous calcium phosphate: in vitro biomineralization and cytocompatibility of human mesenchymal stem cells

Polyethylene is widely used as a component of implants in medicine. Composites made of high-density polyethylene (HDPE) containing different amounts of amorphous calcium phosphate nanoparticles were investigated concerning their in vitro biomedical performance. The nanoparticles were produced by flame spray synthesis and extruded with HDPE, the latter complying with Food and Drug Administration regulations. Mechanical properties such as Young's modulus and contact angle as well as in vitro biomineralization of the nanocomposites hot-pressed into thin films were evaluated. The deposition of a hydroxyapatite layer occurred upon immersion in simulated body fluid. Additionally, a cell culture study with human mesenchymal stem cells for six weeks allowed a primary assessment of the cytocompatibility. Viability assays (alamarBlue and lactate dehydrogenase detection) proved the absence of cytotoxic effects of the scaffolds. Microscopic images after hematoxylin and eosin staining confirmed typical growth and morphology. A preliminary experiment analyzed the alkaline phosphatase activity after two weeks. These findings motivate further investigations on bioactive HDPE in bone tissue engineering