34 research outputs found

    The Interplay between Financial Conditions and Monetary Policy Shocks

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    We study the interplay between monetary policy and financial conditions shocks. Such shocks have a significant and similar impact on the real economy, though with different degrees of persistence. The systematic fed funds rate response to a financial shock contributes to bringing the economy back towards trend, but a zero lower bound on policy rates can prevent this from happening, with a significant cost in terms of output and investment. In a retrospective analysis of the U.S. economy over the past 20 years, we decompose the realization of economic variables into the contributions of financial, monetary policy, and other shocks

    Impact of foliar herbivory on the development of a root-feeding insect and its parasitoid

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    The majority of studies exploring interactions between above- and below-ground biota have been focused on the effects of root-associated organisms on foliar herbivorous insects. This study examined the effects of foliar herbivory by Pieris brassicae L. (Lepidoptera: Pieridae) on the performance of the root herbivore Delia radicum L. (Diptera: Anthomyiidae) and its parasitoid Trybliographa rapae (Westwood) (Hymenoptera: Figitidae), mediated through a shared host plant Brassica nigra L. (Brassicaceae). In the presence of foliar herbivory, the survival of D. radicum and T. rapae decreased significantly by more than 50%. In addition, newly emerged adults of both root herbivores and parasitoids were significantly smaller on plants that had been exposed to foliar herbivory than on control plants. To determine what factor(s) may have accounted for the observed results, we examined the effects of foliar herbivory on root quantity and quality. No significant differences in root biomass were found between plants with and without shoot herbivore damage. Moreover, concentrations of nitrogen in root tissues were also unaffected by shoot damage by P. brassicae larvae. However, higher levels of indole glucosinolates were measured in roots of plants exposed to foliar herbivory, suggesting that the development of the root herbivore and its parasitoid may be, at least partly, negatively affected by increased levels of these allelochemicals in root tissues. Our results show that foliar herbivores can affect the development not only of root-feeding insects but also their natural enemies. We argue that such indirect interactions between above- and below-ground biota may play an important role in the structuring and functioning of communities

    Obesity Is Associated with Altered Tumor Metabolism in Metastatic Melanoma

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    PURPOSE: Overweight/obese (OW/OB) patients with metastatic melanoma unexpectedly have improved outcomes with immune checkpoint inhibitors (ICI) and BRAF-targeted therapies. The mechanism(s) underlying this association remain unclear, thus we assessed the integrated molecular, metabolic, and immune profile of tumors, as well as gut microbiome features, for associations with patient body mass index (BMI). EXPERIMENTAL DESIGN: Associations between BMI [normal (NL \u3c 25) or OW/OB (BMI ≥ 25)] and tumor or microbiome characteristics were examined in specimens from 782 patients with metastatic melanoma across 7 cohorts. DNA associations were evaluated in The Cancer Genome Atlas cohort. RNA sequencing from 4 cohorts (n = 357) was batch corrected and gene set enrichment analysis (GSEA) by BMI category was performed. Metabolic profiling was conducted in a subset of patients (x = 36) by LC/MS, and in flow-sorted melanoma tumor cells (x = 37) and patient-derived melanoma cell lines (x = 17) using the Seahorse XF assay. Gut microbiome features were examined in an independent cohort (n = 371). RESULTS: DNA mutations and copy number variations were not associated with BMI. GSEA demonstrated that tumors from OW/OB patients were metabolically quiescent, with downregulation of oxidative phosphorylation and multiple other metabolic pathways. Direct metabolite analysis and functional metabolic profiling confirmed decreased central carbon metabolism in OW/OB metastatic melanoma tumors and patient-derived cell lines. The overall structure, diversity, and taxonomy of the fecal microbiome did not differ by BMI. CONCLUSIONS: These findings suggest that the host metabolic phenotype influences melanoma metabolism and provide insight into the improved outcomes observed in OW/OB patients with metastatic melanoma treated with ICIs and targeted therapies

    Root Herbivore Effects on Aboveground Multitrophic Interactions: Patterns, Processes and Mechanisms

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    In terrestrial food webs, the study of multitrophic interactions traditionally has focused on organisms that share a common domain, mainly above ground. In the last two decades, it has become clear that to further understand multitrophic interactions, the barrier between the belowground and aboveground domains has to be crossed. Belowground organisms that are intimately associated with the roots of terrestrial plants can influence the levels of primary and secondary chemistry and biomass of aboveground plant parts. These changes, in turn, influence the growth, development, and survival of aboveground insect herbivores. The discovery that soil organisms, which are usually out of sight and out of mind, can affect plant-herbivore interactions aboveground raised the question if and how higher trophic level organisms, such as carnivores, could be influenced. At present, the study of above-belowground interactions is evolving from interactions between organisms directly associated with the plant roots and shoots (e.g., root feeders - plant - foliar herbivores) to interactions involving members of higher trophic levels (e.g., parasitoids), as well as non-herbivorous organisms (e.g., decomposers, symbiotic plant mutualists, and pollinators). This multitrophic approach linking above- and belowground food webs aims at addressing interactions between plants, herbivores, and carnivores in a more realistic community setting. The ultimate goal is to understand the ecology and evolution of species in communities and, ultimately how community interactions contribute to the functioning of terrestrial ecosystems. Here, we summarize studies on the effects of root feeders on aboveground insect herbivores and parasitoids and discuss if there are common trends. We discuss the mechanisms that have been reported to mediate these effects, from changes in concentrations of plant nutritional quality and secondary chemistry to defense signaling. Finally, we discuss how the traditional framework of fixed paired combinations of root- and shoot-related organisms feeding on a common plant can be transformed into a more dynamic and realistic framework that incorporates community variation in species, densities, space and time, in order to gain further insight in this exciting and rapidly developing field

    Global variability in leaf respiration in relation to climate, plant functional types and leaf traits

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    • Leaf dark respiration (Rdark) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. • Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark. • Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8–28°C). By contrast, Rdark at a standard T (25°C, Rdark25) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark25 at a given photosynthetic capacity (Vcmax25) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark25 values at any given Vcmax25 or [N] were higher in herbs than in woody plants. • The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs)

    Low-Loss Complex Permittivity and Permeability Determination in Transmission/Reflection Measurements with Time-Domain Smoothing

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    Abstract-An approach is proposed for determination of the complex permittivity and permeability of low-loss materials, eliminating half-wavelength resonances occurring in transmission/reflection (T/R) measurements. To this end, we apply time-domain smoothing for removing resonant artifacts from the wave impedance obtained with the conventional T/R method, assuming that we do not have such artifacts in the refractive index. Accordingly, the permittivity and permeability are found from the smoothed wave impedance and conventional refractive index. Our method is validated by measurements for two different low-loss materials, nylon and lithium ferrite, and those results are discussed. Further, results from the present approach are compared to those from the approximate approach derived in our previous work
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