29,438 research outputs found

    Household Income and Vehicle Fuel Economy in California

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    This white paper presents the findings from an analysis of the fiscal implications for vehicle owners of changing from the current statewide fuel tax to a ā€œroad user chargeā€ (RUC) based on vehicle-miles traveled (VMT). Since 1923, Californiaā€™s motor vehicle fuel tax has provided revenue used to plan, construct, and maintain the stateā€™s publicly funded transportation systems. Over time, improvements in vehicle fuel efficiency and the effects of inflation have reduced both the revenue from the fuel tax and its purchasing power. Thus, there is growing interest among policy makers for replacing the stateā€™s per-gallon fuel tax with an RUC based on VMT. This study analyzes the 2010-2011California Household Travel Survey (CHTS) to identify the potential effects this policy change would be likely to have on households across the state. The analysis found that while daily household fuel consumption and VMT both appear to increase with household income, urban and rural households show roughly the same amount of fuel consumption and VMT. No statistically significant difference in cost was found between the two programs in any income group. This suggests that an RUC designed to collect the same amount of revenues statewide as the current fuel tax would not place a significant financial burden on California households

    Monolayer graphene bolometer as a sensitive far-IR detector

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    In this paper we give a detailed analysis of the expected sensitivity and operating conditions in the power detection mode of a hot-electron bolometer (HEB) made from a few {\mu}m2^2 of monolayer graphene (MLG) flake which can be embedded into either a planar antenna or waveguide circuit via NbN (or NbTiN) superconducting contacts with critical temperature ~ 14 K. Recent data on the strength of the electron-phonon coupling are used in the present analysis and the contribution of the readout noise to the Noise Equivalent Power (NEP) is explicitly computed. The readout scheme utilizes Johnson Noise Thermometry (JNT) allowing for Frequency-Domain Multiplexing (FDM) using narrowband filter coupling of the HEBs. In general, the filter bandwidth and the summing amplifier noise have a significant effect on the overall system sensitivity. The analysis shows that the readout contribution can be reduced to that of the bolometer phonon noise if the detector device is operated at 0.05 K and the JNT signal is read at about 10 GHz where the Johnson noise emitted in equilibrium is substantially reduced. Beside the high sensitivity (NEP < 10āˆ’20^{-20} W/Hz1/2^{1/2}, this bolometer does not have any hard saturation limit and thus can be used for far-IR sky imaging with arbitrary contrast. By changing the operating temperature of the bolometer the sensitivity can be fine tuned to accommodate the background photon flux in a particular application. By using a broadband low-noise kinetic inductance parametric amplifier, ~100s of graphene HEBs can be read simultaneously without saturation of the system output.Comment: 9 pages. 6 figure, SPIE Astronomical Telescopes + Instrumentation, Montr\'eal, Quebec, Canada, 22-27 June, 201

    Nova Aquilae 1918 (V603 Aql) Faded by 0.44 mag/century from 1938-2013

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    We present the light curve of the old nova V603 Aql (Nova Aql 1918) from 1898-1918 and 1934-2013 using 22,721 archival magnitudes. All of our magnitudes are either in, or accurately transformed into, the Johnson BB and VV magnitude systems. This is vital because offsets in old sequences and the visual-to-VV transformation make for errors from 0.1-1.0 magnitude if not corrected. Our V603 Aql light curve is the first time that this has been done for any nova. Our goal was to see the evolution of the mass accretion rate on the century time scale, and to test the long-standing prediction of the Hibernation model that old novae should be fading significantly in the century after their eruption is long over. The 1918 nova eruption was completely finished by 1938 when the nova decline stopped, and when the star had faded to fainter than its pre-nova brightness of B=11.43Ā±0.03B=11.43 \pm 0.03 mag. We find that the nova light from 1938-2013 was significantly fading, with this being seen consistently in three independent data sets (the Sonneberg plates in BB, the AAVSO VV light curve, and the non-AAVSO VV light curve). We find that V603 Aql is declining in brightness at an average rate of 0.44Ā±0.040.44 \pm 0.04 mag per century since 1938. This work provides remarkable confirmation of an important prediction of the Hibernation model.Comment: 13 pages, 1 figure, 2 electronic online data tables, Accepted for publication ApJLet

    Iodine and pregnancy ā€“ a UK cross-sectional survey of dietary intake, knowledge and awareness

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    Iodine is a key component of the thyroid hormones, which are critical for healthy growth, development and metabolism. The UK population is now classified as mildly iodine-insufficient. Adequate levels of iodine during pregnancy are essential for fetal neurodevelopment, and mild iodine deficiency is linked to developmental impairments. In the absence of prophylaxis in the UK, awareness of nutritional recommendations during pregnancy would empower mothers to make the right dietary choices leading to adequate iodine intake. The present study aimed to: estimate mothers' dietary iodine intake in pregnancy (using a FFQ); assess awareness of the importance of iodine in pregnancy with an understanding of existing pregnancy dietary and lifestyle recommendations with relevance for iodine; examine the level of confidence in meeting adequate iodine intake. A cross-sectional survey was conducted and questionnaires were distributed between August 2011 and February 2012 on local (Glasgow) and national levels (online electronic questionnaire); 1026 women, UK-resident and pregnant or mother to a child aged up to 36 months participated in the study. While self-reported awareness about general nutritional recommendations during pregnancy was high (96 %), awareness of iodine-specific recommendations was very low (12 %), as well as the level of confidence of how to achieve adequate iodine intake (28 %). Median pregnancy iodine intake, without supplements, calculated from the FFQ, was 190 Ī¼g/d (interquartile range 144ā€“256Ī¼g/d), which was lower than that of the WHO's recommended intake for pregnant women (250 Ī¼g/d). Current dietary recommendations in pregnancy, and their dissemination, are found not to equip women to meet the requirements for iodine intake

    CONJOINT ANALYSIS OF GROUNDWATER PROTECTION PROGRAMS

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    Three conjoint models-a traditional ratings model, a ratings difference specification, and a binary response model-were used to value groundwater protection program alternatives. The last, which is virtually identical to a dichotomous choice contingent valuation specification, produced the smallest value estimates. This suggests that the conjoint model is very sensitive to model specifications and that traditional conjoint models may overestimate economic value because many respondents are not in the market for the commodity being valued.Resource /Energy Economics and Policy,
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