960 research outputs found
The Effects of Tax-Based Saving Incentives On Saving and Wealth
This paper evaluates research examining the effects of tax-based saving incentives on private and national saving. Several" factors make this an unusually difficult problem. First, households that participate in, or are eligible for, saving incentive plans have systematically stronger tastes for saving than other households. Second, the data indicate that households with saving incentives have taken on more debt than other households. Third, significant changes in the 1980s in financial markets, pensions, social security, and nonfinancial assets interacted with the expansion of saving incentives. Fourth, saving incentive accounts represent pre-tax balances, whereas conventional taxable accounts represent post-tax balances. Fifth, the fact that employer contributions to saving incentive plans are a part of total employee compensation is typically ignored. A major theme of this paper is that analyses that ignore these issues overstate the impact of saving incentives on saving. We show that accounting for these factors largely or completely eliminates the estimated positive impact of saving incentives on saving found in the literature. Thus, we conclude that little if any of the overall contributions to existing saving incentives have raised private or national saving. *Portions of this article were published in the JEP, 1996, under title of "The Illusory Effects of Saving Incentives on Saving."
Fine structure of an oceanic crustal section near the East Pacific Rise
In this study we model synthetically a complete seismic profile of roughly 20-m.y.-old crust located to the west of the East Pacific Rise, 3.37S, 114.13W. The results indicate a rather strong velocity gradient below the sediments with little evidence of layering in the upper crust and a slightly dipping oceanic layer. The crust-to-mantle transition zone appears sharp providing a relatively good wave guide for multiple Moho reflections which are modeled synthetically to further test the usefulness of a layered earth model in explaining entire seismograms. The mantle head waves decay abruptly near 50 km which can be explained by the onset of a low-velocity zone in the upper mantle at about a depth of 12 km below the ocean surface
Modeling the long-period body waves from shallow earthquakes at regional ranges
A procedure for modeling P and PL waves recorded on long-period WWSSN instruments at ranges 1° to 12° is presented. Following the experience gained by modeling explosions (Helmberger, 1972), we demonstrate that these long-period phases are adequately treated by a single crustal layer for most of Western United States. After generating the Green's functions at the various ranges for the three fundamental dislocation types, we need only construct linear combinations of these vectors to represent any arbitrary oriented earthquake. The waveform patterns produced from the various fault types are quite diagnostic with the dip-slip orientations showing a strong ringing nature which is caused by the vertical SV lobes. To test the usefulness of this technique, we construct synthetics for some well-studied west coast earthquakes where the orientation, time history, and moment have been determined independently. Comparing the predicted seismograms with observations, we find good agreement in waveshapes and amplitudes
Conical emission, pulse splitting and X-wave parametric amplification in nonlinear dynamics of ultrashort light pulses
The precise observation of the angle-frequency spectrum of light filaments in
water reveals a scenario incompatible with current models of conical emission
(CE). Its description in terms of linear X-wave modes leads us to understand
filamentation dynamics requiring a phase- and group-matched, Kerr-driven
four-wave-mixing process that involves two highly localized pumps and two
X-waves. CE and temporal splitting arise naturally as two manifestations of
this process
Exploring the digital competence of pre-service teachers on entry onto an initial teacher education programme in Ireland
peer-reviewedThis study aimed to explore the digital competence of recent entrants into a pre-service teacher education programme in an Irish University. The participants were drawn from a cohort of 208 undergraduate teacher education students. The study employed an online survey that captured both self-reported levels of digital competence and knowledge of key areas of cyber ethics and digital technology. The respondents were active users of technology and very frequent users of social media but reported levels of skills in the use of other digital technologies was lower. In addition, their knowledge of cyber-ethics and associated practices varied. The study also found that they were positively disposed to technology in teaching. The paper argues that, while there are limitations to surveys that aim to capture one’s level of digital competence, they can help guide teacher educators in responding to pre-service teachers. However, digital competence is an evolving concept and care must be taken to ensure that frameworks and tools used to assess it do not stifle teachers’ autonomy in relation to their utilisation of technology
Low-Cost Electronic Microwave Calibration for Rapid On-Line Moisture Sensing of Seedcotton
In order to improve rapid on-line moisture sensing of seedcotton in cotton gins, a means by which to establish a reliable low-cost wide-band electronic calibration is critically needed. This calibration is needed to center the circuit due to changes in the internal signal delays and attenuation drift caused by temperature changes in the various system components and circuit elements. This research examines a hardware technique for use in conjunction with microwave reflective sensing probes having an extended bandwidth from 500 MHz through 2.5 GHz. This new technique was validated experimentally against known electrical propagation delay standards. Results of the measured propagation delay with this type of automatic electronic calibration method was found to agree with results using a vector network analyzer with a traditional S11 single port error correction calibration methodology to within 4% of the measurement, 95% confidence, with a standard error of +/− 18.6 ps for the delay measurements. At this level of performance, the proposed low-cost technique exhibits superior performance, over the typical geosciences time-domain reflectometer “TDR”, instruments in common use in soil moisture testing and is suitable for use in cotton gin moisture sensing
Upper-mantle cross-section from California to Greenland
Pure-path upper-mantle models appropriate for tectonic, shield and old ocean have been recently presented by Grand and Helmberger. This was accomplished by modeling a rather restricted data set of S and SS triplication waveforms as well as the beginning portion of the Love waves. A much larger data set of S, SS and SSS, etc. (multibounce S-wave triplications) with a mixture of tectonic paths is available. In particular, events usually occur at tectonic margins and are recorded on stable continents. We present results of modeling these observations for laterally varying structure, essentially along a profile from California to Greenland. The models are allowed to be locally dipping with the lithosphere thickening with age at the expense of a dwindling low-velocity zone. Lateral variation does not appear to be required for depths greater than 400 km along this particular profile. The best-fitting model has a large increase in lithospheric thickness near the Rocky Mountain Front, roughly an increase of 75 km in thickness over a horizontal distance of 400 km or less. The low-velocity zone, with a velocity of 4.4 km/s, is replaced by a much faster upper 300 km with velocities near 4.7 km/s or a 7% overall increase. The one-way travel time jumps by roughly 4 s across this boundary, which compares reasonably well with the direct S residuals obtained from deep earthquake data although the latter data show large scatter.
ARK: https://n2t.net/ark:/88439/y069500
Permalink: https://geophysicsjournal.com/article/12
 
Human-machine networks: Towards a typology and profiling framework
© Springer International Publishing Switzerland 2016. In this paper we outline an initial typology and framework for the purpose of profiling human-machine networks, that is, collective structures where humans and machines interact to produce synergistic effects. Profiling a humanmachine network along the dimensions of the typology is intended to facilitate access to relevant design knowledge and experience. In this way the profiling of an envisioned or existing human-machine network will both facilitate relevant design discussions and, more importantly, serve to identify the network type. We present experiences and results from two case trials: a crisis management system and a peerto- peer reselling network. Based on the lessons learnt from the case trials we suggest potential benefits and challenges, and point out needed future work
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