988 research outputs found
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On the electron-induced isotope fractionation in low temperature <sup>32</sup>O<sub>2</sub>/<sup>36</sup>O<sub>2</sub> ices—ozone as a case study
The formation of six ozone isotopomers and isotopologues, 16O16O16O, 18O18O18O, 16O16O18O, 18O18O16O, 16O18O16O, and 18O16O18O, has been studied in electron-irradiated solid oxygen 16O2 and 18O2 (1 : 1) ices at 11 K. Significant isotope effects were found to exist which involved enrichment of 18O-bearing ozone molecules. The heavy 18O18O18O species is formed with a factor of about six higher than the corresponding 16O16O16O isotopologue. Likewise, the heavy 18O18O16O species is formed with abundances of a factor of three higher than the lighter 16O16O18O counterpart. No isotope effect was observed in the production of 16O18O16O versus 18O16O18O. Such studies on the formation of distinct ozone isotopomers and isotopologues involving non-thermal, non-equilibrium chemistry by irradiation of oxygen ices with high energy electrons, as present in the magnetosphere of the giant planets Jupiter and Saturn, may suggest that similar mechanisms may contribute to the 18O enrichment on the icy satellites of Jupiter and Saturn such as Ganymede, Rhea, and Dione. In such a Solar System environment, energetic particles from the magnetospheres of the giant planets may induce non-equilibrium reactions of suprathermal and/or electronically excited atoms under conditions, which are quite distinct from isotopic enrichments found in classical, thermal gas phase reactions
Verifying and Monitoring IoTs Network Behavior using MUD Profiles
IoT devices are increasingly being implicated in cyber-attacks, raising
community concern about the risks they pose to critical infrastructure,
corporations, and citizens. In order to reduce this risk, the IETF is pushing
IoT vendors to develop formal specifications of the intended purpose of their
IoT devices, in the form of a Manufacturer Usage Description (MUD), so that
their network behavior in any operating environment can be locked down and
verified rigorously. This paper aims to assist IoT manufacturers in developing
and verifying MUD profiles, while also helping adopters of these devices to
ensure they are compatible with their organizational policies and track devices
network behavior based on their MUD profile. Our first contribution is to
develop a tool that takes the traffic trace of an arbitrary IoT device as input
and automatically generates the MUD profile for it. We contribute our tool as
open source, apply it to 28 consumer IoT devices, and highlight insights and
challenges encountered in the process. Our second contribution is to apply a
formal semantic framework that not only validates a given MUD profile for
consistency, but also checks its compatibility with a given organizational
policy. We apply our framework to representative organizations and selected
devices, to demonstrate how MUD can reduce the effort needed for IoT acceptance
testing. Finally, we show how operators can dynamically identify IoT devices
using known MUD profiles and monitor their behavioral changes on their network.Comment: 17 pages, 17 figures. arXiv admin note: text overlap with
arXiv:1804.0435
Enabling Future Sustainability Transitions: An Urban Metabolism Approach to Los Angeles Pincetl et al. Enabling Future Sustainability Transitions
Summary: This synthesis article presents an overview of an urban metabolism (UM) approach using mixed methods and multiple sources of data for Los Angeles, California. We examine electric energy use in buildings and greenhouse gas emissions from electricity, and calculate embedded infrastructure life cycle effects, water use and solid waste streams in an attempt to better understand the urban flows and sinks in the Los Angeles region (city and county). This quantification is being conducted to help policy-makers better target energy conservation and efficiency programs, pinpoint best locations for distributed solar generation, and support the development of policies for greater environmental sustainability. It provides a framework to which many more UM flows can be added to create greater understanding of the study area's resource dependencies. Going forward, together with policy analysis, UM can help untangle the complex intertwined resource dependencies that cities must address as they attempt to increase their environmental sustainability
The G-O Rule and Waldmeier Effect in the Variations of the Numbers of Large and Small Sunspot Groups
We have analysed the combined Greenwich and Solar Optical Observing Network
(SOON) sunspot group data during the period of 1874-2011 and determined
variations in the annual numbers (counts) of the small, large and big sunspot
groups (these classifications are made on the basis of the maximum areas of the
sunspot groups). We found that the amplitude of an even-numbered cycle of the
number of large groups is smaller than that of its immediately following
odd-numbered cycle. This is consistent with the well known Gnevyshev and Ohl
rule or G-O rule of solar cycles, generally described by using the Zurich
sunspot number (Rz). During cycles 12-21 the G-O rule holds good for the
variation in the number of small groups also, but it is violated by cycle pair
(22, 23) as in the case of Rz. This behaviour of the variations in the small
groups is largely responsible for the anomalous behaviour of Rz in cycle pair
(22, 23). It is also found that the amplitude of an odd-numbered cycle of the
number of small groups is larger than that of its immediately following
even-numbered cycle. This can be called as `reverse G-O rule'. In the case of
the number of the big groups, both cycle pairs (12, 13) and (22, 23) violated
the G-O rule. In many cycles the positions of the peaks of the small, large,
and big groups are different and considerably differ with respect to the
corresponding positions of the Rz peaks. In the case of cycle 23, the
corresponding cycles of the small and large groups are largely symmetric/less
asymmetric (Waldmeier effect is weak/absent) with their maxima taking place two
years later than that of Rz. The corresponding cycle of the big groups is more
asymmetric (strong Waldmeier effect) with its maximum epoch taking place at the
same time as that of Rz.Comment: 13 pages, 5 figures, 1 table, accepted by Solar Physic
CART Raman Lidar Aerosol and Water Vapor Measurements in the Vicinity of Clouds
Aerosol and water vapor profiles acquired by the Raman lidar instrument located at the Climate Research Facility (CRF) at Southern Great Plains (SGP) provide data necessary to investigate the atmospheric variability in the vicinity of clouds near the top of the planetary boundary layer (PBL). Recent CARL upgrades and modifications to the routine processing algorithms afforded the necessarily high temporal and vertical data resolutions for these investigations. CARL measurements are used to investigate the behavior of aerosol backscattering and extinction and their correlation with water vapor and relative humidity
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