3,283 research outputs found
Nickel electrode plate thickening study
The rate of thickening of the nickel electrode with cycling, under geochronous conditions, was investigated. The experimental procedures used to study the effects of various operational parameters on the rate of the thickness growth are outlined. The parameters included temperature, electrolyte composition, manufacturing lot, cycle parameters, and reconditioning methods
Adaptive dual-comb spectroscopy in the green region
Dual-comb spectroscopy is extended to the visible spectral range with a
set-up based on two frequency-doubled femtosecond ytterbium-doped fiber lasers.
The dense rovibronic spectrum of iodine around 19240 cm-1 is recorded within 12
ms at Doppler-limited resolution with a simple scheme that only uses
free-running femtosecond lasers
It's Not Just the ATMs: Technology, Firm Strategies, Jobs, and Earnings in Retail Banking
The authors examine trends in job content and earnings in selected jobs in two American banks. Firm restructuring and technological changes resulted in higher earnings for college-educated workers. The banks followed different strategies in implementing these changes for lower-skill jobs, with different effects on bank tellers in particular. The authors conclude that technology enables workplace reform but does not determine its effect on jobs and earnings; these effects are contingent on managerial strategies. This focus on organizational processes and managerial strategy provides a complementary approach to accounts of growing inequality that center solely on the role of individual skills and technological change.
Coherent Raman spectro-imaging with laser frequency combs
Optical spectroscopy and imaging of microscopic samples have opened up a wide
range of applications throughout the physical, chemical, and biological
sciences. High chemical specificity may be achieved by directly interrogating
the fundamental or low-lying vibrational energy levels of the compound
molecules. Amongst the available prevailing label-free techniques, coherent
Raman scattering has the distinguishing features of high spatial resolution
down to 200 nm and three-dimensional sectioning. However, combining fast
imaging speed and identification of multiple - and possibly unexpected-
compounds remains challenging: existing high spectral resolution schemes
require long measurement times to achieve broad spectral spans. Here we
overcome this difficulty and introduce a novel concept of coherent anti-Stokes
Raman scattering (CARS) spectro-imaging with two laser frequency combs. We
illustrate the power of our technique with high resolution (4 cm-1) Raman
spectra spanning more than 1200 cm-1 recorded within less than 15 microseconds.
Furthermore, hyperspectral images combining high spectral (10 cm-1) and spatial
(2 micrometers) resolutions are acquired at a rate of 50 pixels per second.
Real-time multiplex accessing of hyperspectral images may dramatically expand
the range of applications of nonlinear microscopy.Comment: 8 pages, 3 figure
Will There Be a New Definition of âPurchase Moneyâ?
This article examines SB 1178 and its potential to significantly modify the CCP 580b antideficiency rule.
The Effect of Growth Rate, Phosphorus Concentration, and Temperature on N-2 Fixation, Carbon Fixation, and Nitrogen Release in Continuous Cultures of Trichodesmium IMS101
With the use of continuous culture systems, rates of dinitrogen (N2) and carbon (C) fixation and nitrogen (N)- and C-based doubling times were assessed in Trichodesmium IMS101 growing exponentially at steady state dilution rates of 0.10, 0.20, and 0.33 d-1 (doubling times of 10, 5, and 3 d - within the range reported for natural populations). Rates of C fixation, N2 fixation, and N release were examined in replicate culture systems with several techniques. Biomass-specific C uptake varied little with population doubling time, but N2 fixation and N release varied markedly among treatments. Total daily gross N2 fixation rates and estimated N release rates were higher in cultures with higher dilution rates. Cultures grown at lower dilution rates had higher daily C:N2 fixation ratios and lower N release rates. Consistent with other studies, it was estimated that Trichodesmium released about 80-90% of their recently fixed N2 during growth. Turnover of cellular C estimated from carbon fixation was a good estimator of population growth rates in steady state cultures, whereas turnover of cellular N estimated from gross or net N2 fixation was not. Small changes in temperature (24°C vs. 28°C) did not appear to affect gross N2 fixation, whereas inorganic phosphorus (1 vs. 5 Όmol L-1) supply had a large effect on N2 fixation. These results suggest that continuous culture systems are excellent for elucidating physiological responses of Trichodesmium under ecologically relevant growth conditions and provide a framework for assessing highly variable field estimates of N2 and C fixation
Raman-induced Kerr-effect dual-comb spectroscopy
We report on the first demonstration of nonlinear dual-frequency-comb
spectroscopy. In multi-heterodyne femtosecond Raman-induced Kerr-effect
spectroscopy, the Raman gain resulting from the coherent excitation of
molecular vibrations by a spectrally-narrow pump is imprinted onto the
femtosecond laser frequency comb probe spectrum. The birefringence signal
induced by the nonlinear interaction of these beams and the sample is
heterodyned against a frequency comb local oscillator with a repetition
frequency slightly different from that of the comb probe. Such time-domain
interference provides multiplex access to the phase and amplitude Raman spectra
over a broad spectral bandwidth within a short measurement time. Experimental
demonstration, at a spectral resolution of 200 GHz, a measurement time of 293
{\mu}s and a sensitivity of 10^-6, is given on liquid samples exhibiting a C-H
stretch Raman shift.Comment: 7 pages, 4 figure
Macroinvertebrate community responses to a dewatering disturbance gradient in a restored stream
Dewatering disturbances are common in aquatic systems and represent a relatively untapped field of disturbance ecology, yet studying dewatering events along gradients in non-dichotomous (i.e. wet/dry) terms is often difficult. Because many stream restorations can essentially be perceived as planned hydrologic manipulations, such systems can make ideal test-cases for understanding processes of hydrological disturbance. In this study we used an experimental drawdown in a 440 ha stream/wetland restoration site to assess aquatic macroinvertebrate community responses to dewatering and subsequent rewetting. The geomorphic nature of the site and the design of the restoration allowed dewatering to occur predictably along a gradient and decoupled the hydrologic response from any geomorphic (i.e. habitat heterogeneity) effects. In the absence of such heterogeneous habitat refugia, reach-scale wetted perimeter and depth conditions exerted a strong control on community structure. The community exhibited an incremental response to dewatering severity over the course of this disturbance, which was made manifest not as a change in community means but as an increase in community variability, or dispersion, at each site. The dewatering also affected inter-species abundance and distributional patterns, as dewatering and rewetting promoted alternate species groups with divergent habitat tolerances. Finally, our results indicate that rapid rewetting â analogous to a hurricane breaking a summer drought â may represent a recovery process rather than an additional disturbance and that such processes, even in newly restored systems, may be rapid
Storage-ring measurement of the hyperfine induced 47Ti18+(2s 2p 3P0 -> 2s2 1S0) transition rate
The hyperfine induced 2s 2p 3P0 > 2s2 1S0 transition rate AHFI in
berylliumlike 47Ti18+ was measured. Resonant electron-ion recombination in a
heavy-ion storage ring was employed to monitor the time dependent population of
the 3P0 state. The experimental value AHFI=0.56(3)/s is almost 60% larger than
theoretically predicted.Comment: 4 pages. 3 figures, 1 table, accepted for publication in Physical
Review Letter
- âŠ