Digital Frequency Domain Multiplexer for mm-Wavelength Telescopes

An FPGA based digital signal processing (DSP) system for biasing and reading out multiplexed bolometric detectors for mm-wavelength telescopes is presented. This readout system is being deployed for balloon-borne and ground based cosmology experiments with the primary goal of measuring the signature of inflation with the Cosmic Microwave Background Radiation. The system consists of analog superconducting electronics running at 250mK and 4K, coupled to digital room temperature backend electronics described here. The digital electronics perform the real time functionality with DSP algorithms implemented in firmware. A soft embedded processor provides all of the slow housekeeping control and communications. Each board in the system synthesizes multi-frequency combs of 8 to 32 carriers in the MHz band to bias the detectors. After the carriers have been modulated with the sky-signal by the detectors, the same boards digitize the comb directly. The carriers are mixed down to base-band and low pass filtered. The signal bandwidth of 0.050 Hz - 100 Hz places extreme requirements on stability and requires powerful filtering techniques to recover the sky-signal from the MHz carriers.Comment: 6 pages, 6 figures, Submitted May 2007 to IEEE Transactions on Nuclear Science (TNS

Doping dependent plasmon dispersion in 2H-transition metal dichalcogenides

We report the behavior of the charge carrier plasmon of 2H-transition metal dichalcogenides (TMDs) as a function of intercalation with alkali metals. Intercalation and concurrent doping of the TMD layers have a substantial impact on plasmon energy and dispersion. While the plasmon energy shifts are related to the intercalation level as expected within a simple homogeneous electron gas picture, the plasmon dispersion changes in a peculiar manner independent of the intercalant and the TMD materials. Starting from a negative dispersion, the slope of the plasmon dispersion changes sign and grows monotonously upon doping. Quantitatively, the increase of this slope depends on the orbital character (4d or 5d) of the conduction bands, which indicates a decisive role of band structure effects on the plasmon behavior.Peer reviewe

An Intertidal Sea Star Adjusts Thermal Inertia to Avoid Extreme Body Temperatures

The body temperature of ectotherms is influenced by the interaction of abiotic conditions, morphology, and behavior. Although organisms living in different thermal habitats may exhibit morphological plasticity or move from unfavorable locations, there are few examples of animals adjusting their thermal properties in response to short-term changes in local conditions. Here, we show that the intertidal sea star Pisaster ochraceus modulates its thermal inertia in response to prior thermal exposure. After exposure to high body temperature at low tide, sea stars increase the amount of colder than-air fluid in their coelomic cavity when submerged during high tide, resulting in a lower body temperature during the subsequent low tide. Moreover, this buffering capacity is more effective when seawater is cold during the previous high tide. This ability to modify the volume of coelomic fluid provides sea stars with a novel thermoregulatory backup when faced with prolonged exposure to elevated aerial temperatures

Barium and Carbon fluxes in the Canadian Arctic Archipelago

Seasonal and spatial variability of dissolved Barium (Ba) in Amundsen Gulf, southeastern Beaufort Sea, was monitored over a full year from September 2007 to September 2008. Dissolved Ba displays a nutrient-type behavior: the maximum water column concentration is located below the surface layer. Highest Ba concentrations are typically observed at river mouths, the lowest concentrations are found in water masses of Atlantic origin. Barium concentrations decrease eastward through the Canadian Arctic Archipelago. Barite (BaSO4) saturation is reached at the maximum concentrations of dissolved Ba in the subsurface layer, whereas the remaining water column is undersaturated. A three end-member mixing model comprising freshwater from sea-ice melt and rivers, as well as upper halocline water, was used to establish their relative contributions to the Ba concentrations in the upper water column of the Amundsen Gulf. Based on water column and riverine Ba contributions, we assess the depletion of dissolved Ba by formation and concomitant sinking of biologically bound Ba (bio-Ba), from which we derive an estimate of the carbon export production. In the upper 50 m of the water column of Amundsen Gulf, riverine Ba accounts for up to 15% of the available dissolved Ba inventory, of which up to 20% is depleted by bio-Ba formation and export. Since riverine inputs and Ba export occur concurrently, the seasonal variability of dissolved Ba in the upper water column is moderate. Assuming a fixed organic carbon to bio-Ba flux ratio, carbon export out of the surface layer is estimated at 1.8{plus minus}0.45 mol C m‑2 yr‑1. We propose a climatological carbon budget for the Amundsen Gulf

Mapping of the digital climate nudges in Nordic online grocery stores

This paper explores how 21 Nordic online food retailers nudge their customers towards more climate-friendly food choices. We use a choice architecture taxonomy dividing the nudges into decision information, decision structure, and decision assistance. We find that most retailers use several types of climate nudges. Most of these are decision information type nudges, such as personalized carbon footprint apps and climate labels. Wide use of non-salient nudges, often presenting the climate impact after the customers have made their purchase, limits the potential impact of information on consumers' environmental footprints. Furthermore, the use of broad climate categories and aggregated CO2 measures reflect the challenges in calculating the footprints of individual products. The lack of industry-wide standards for emission data and climate labels makes the current situation challenging for customers wanting to compare emissions across stores. Our results also show that few stores have any form of decision structure or decision assistance nudges, even though these are often found to be themost effective types in the literature on nudges.We endwith discussing promising digital climate nudging opportunities for retailers seeking to reduce the environmental footprint of their customers.publishedVersio

Digital Frequency Domain Multiplexer for mm-Wavelength Telescopes

An FPGA based digital signal processing (DSP) system for biasing and reading out multiplexed bolometric detectors for mm-wavelength telescopes is presented. This readout system is being deployed for balloon-borne and ground based cosmology experiments with the primary goal of measuring the signature of inflation with the Cosmic Microwave Background Radiation. The system consists of analog superconducting electronics running at 250 mK and 4 K, coupled to digital room temperature backend electronics described here. The digital electronics perform the real time functionality with DSP algorithms implemented in firmware. A soft embedded processor provides all of the slow housekeeping control and communications. Each board in the system synthesizes multi-frequency combs of 8 to 32 carriers in the MHz band to bias the detectors. After the carriers have been modulated with the sky-signal by the detectors, the same boards digitize the comb directly. The carriers are mixed down to base-band and low pass filtered. The signal bandwidth of 0.050Hz-100 Hz places extreme requirements on stability and requires powerful filtering techniques to recover the sky-signal from the MHz carriers

Natural History Note An Intertidal Sea Star Adjusts Thermal Inertia to Avoid Extreme Body Temperatures

abstract: The body temperature of ectotherms is influenced by the interaction of abiotic conditions, morphology, and behavior. Although organisms living in different thermal habitats may exhibit morphological plasticity or move from unfavorable locations, there are few examples of animals adjusting their thermal properties in response to short-term changes in local conditions. Here, we show that the intertidal sea star Pisaster ochraceus modulates its thermal inertia in response to prior thermal exposure. After exposure to high body temperature at low tide, sea stars increase the amount of colderthan-air fluid in their coelomic cavity when submerged during high tide, resulting in a lower body temperature during the subsequent low tide. Moreover, this buffering capacity is more effective when seawater is cold during the previous high tide. This ability to modify the volume of coelomic fluid provides sea stars with a novel thermoregulatory "backup" when faced with prolonged exposure to elevated aerial temperatures

OMIP contribution to CMIP6: experimental and diagnostic protocol for the physical component of the Ocean Model Intercomparison Project

The Ocean Model Intercomparison Project (OMIP) is an endorsed project in the Coupled Model Intercomparison Project Phase 6 (CMIP6). OMIP addresses CMIP6 science questions, investigating the origins and consequences of systematic model biases. It does so by providing a framework for evaluating (including assessment of systematic biases), understanding, and improving ocean, sea-ice, tracer, and biogeochemical components of climate and earth system models contributing to CMIP6. Among the WCRP Grand Challenges in climate science (GCs), OMIP primarily contributes to the regional sea level change and near-term (climate/decadal) prediction GCs. OMIP provides (a) an experimental protocol for global ocean/sea-ice models run with a prescribed atmospheric forcing; and (b) a protocol for ocean diagnostics to be saved as part of CMIP6. We focus here on the physical component of OMIP, with a companion paper (Orr et al., 2016) detailing methods for the inert chemistry and interactive biogeochemistry. The physical portion of the OMIP experimental protocol follows the interannual Coordinated Ocean-ice Reference Experiments (CORE-II). Since 2009, CORE-I (Normal Year Forcing) and CORE-II (Interannual Forcing) have become the standard methods to evaluate global ocean/sea-ice simulations and to examine mechanisms for forced ocean climate variability. The OMIP diagnostic protocol is relevant for any ocean model component of CMIP6, including the DECK (Diagnostic, Evaluation and Characterization of Klima experiments), historical simulations, FAFMIP (Flux Anomaly Forced MIP), C4MIP (Coupled Carbon Cycle Climate MIP), DAMIP (Detection and Attribution MIP), DCPP (Decadal Climate Prediction Project), ScenarioMIP, HighResMIP (High Resolution MIP), as well as the ocean/sea-ice OMIP simulations

Lake Monroe Diagnostic And Feasibility Study

This diagnostic and feasiblity has two primary purposes: (1) to diagnose problems with Lake Monroe and (2) identify technically feasible solutions to the problems identified. The protocol used to conduct this study is specified in guidance materials provided by the U.S. Environmental Protection Agency.Prepared for: Monroe County Commissioners, Courthouse Room 302, Bloomington, IN 4740