Magnetic dynamics with spin transfer torques near the Curie temperature

We use atomistic stochastic Landau-Lifshitz-Slonczewski simulations to study the interaction between large thermal fluctuations and spin transfer torques in the magnetic layers of spin valves. At temperatures near the Curie temperature $T_{\rm C}$, spin currents measurably change the size of the magnetization (i.e. there is a {\it longitudinal} spin transfer effect). The change in magnetization of the free magnetic layer in a spin valve modifies the temperature dependence of the applied field-applied current phase diagram for temperatures near $T_{\rm C}$. These atomistic simulations can be accurately described by a Landau-Lifshitz-Bloch + Slonczewski equation, which is a thermally averaged mean field theory. Both the simulation and the mean field theory show that a longitudinal spin transfer effect can be a substantial fraction of the magnetization close to $T_{\rm C}$.Comment: 8 pages, 6 figure

Modeling the impact of zooplankton diel vertical migration on the carbon export flux of the biological pump

Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 33(2), (2019): 181-199. doi:10.1029/2018GB005983.One pathway of the biological pump that remains largely unquantified in many export models is the active transport of carbon from the surface ocean to the mesopelagic by zooplankton diel vertical migration (DVM). Here, we develop a simple representation of zooplankton DVM and implement it in a global export model as a thought experiment to illustrate the effects of DVM on carbon export and mesopelagic biogeochemistry. The model is driven by diagnostic satellite measurements of net primary production, algal biomass, and phytoplankton size structure. Due to constraints on available satellite data, the results are restricted to the latitude range from 60°N to 60°S. The modeled global export flux from the base of the euphotic zone was 6.5 PgC/year, which represents a 14% increase over the export flux in model runs without DVM. The mean (± standard deviation, SD) proportional contribution of the DVM‐mediated export flux to total carbon export, averaged over the global domain and the climatological seasonal cycle, was 0.16 ± 0.04 and the proportional contribution of DVM activity to total respiration within the twilight zone was 0.16 ± 0.06. Adding DVM activity to the model also resulted in a deep local maximum in the oxygen utilization profile. The model results were most sensitive to the assumptions for the fraction of individuals participating in DVM, the fraction of fecal pellets produced in the euphotic zone, and the fraction of grazed carbon that is metabolized.Support for this work came from the National Science Foundation (OCE‐1434000 and OCE‐1657803) and the National Aeronautics and Space Administration (NASA) as part of the EXport Processes in the global Ocean from RemoTe Sensing (EXPORTS) field campaign (grant 80NSSC17K0692) and the North Atlantic Aerosol and Marine Ecosystems Study (NAAMES, grants NNX15AE72G and 80NSSC18K0018). The satellite data used as drivers for the model are available as supporting information. The World Ocean Atlas data (World Ocean Atlas 2009, Annual Climatology, 1 degree, Temperature, Salinity, Oxygen) containing temperature and oxygen measurements can be downloaded from the ERDAPP data server (https://coastwatch.pfeg.noaa.gov/erddap/index.html).2019-07-1

Time to revise the paradigm of hantavirus syndromes? Hantavirus pulmonary syndrome caused by European hantavirus

Hantaviruses have previously been recognised to cause two separate syndromes: hemorrhagic fever with renal syndrome in Eurasia, and hantavirus pulmonary syndrome (HPS) in the Americas. However, increasing evidence suggests that this dichotomy is no longer fruitful when recognising human hantavirus disease and understanding the pathogenesis. Herein are presented three cases of severe European Puumala hantavirus infection that meet the HPS case definition. The clinical and pathological findings were similar to those found in American hantavirus patients. Consequently, hantavirus infection should be considered as a cause of acute respiratory distress in all endemic areas worldwide

The quality of political information

The article conceptualizes the quality of political information and shows how the concept can be used for empirical research. I distinguish three aspects of quality (intelligibility, relevance, validity) and use them to judge the constituent foundations of political information, that is component claims (statements of alleged facts) and connection claims (argumentative statements created by causally linking two component claims). The resulting conceptual map thus entails six manifestations of information quality (component claimintelligibility, connection claim intelligibility, component claimrelevance, connection claim relevance, component claim validity, and connection claim validity). I explain how the conceptual map can be used to make sense of the eclectic variety of existing research, and how it can advance new empirical research, as a guide for determining variation in information quality, as a conceptual template for the analysis of different types of political messages and their common quality deficiencies, and as a generator of new research questions and theoretical expectations