2,473 research outputs found
CAD/CAM techniques for the conservative and efficient management of tooth wear
The prevalence of tooth wear has increased significantly in recent decades. Whilst many treatment approaches are available, there is no consensus on the best materials or techniques. Advances in digital workflows have the potential to reduce the biological cost of treatment, improve treatment outcomes and reduce costs. This article describes modern CAD/CAM techniques which preserve tooth tissue and improve efficiency
A Technique for Narrowband Time Series Photometry: the X-ray Star V2116 Oph
We have used innovative features of the Taurus Tunable Filter instrument on
the 3.9-m Anglo-Australian Telescope to obtain nearly-continuous,
high-throughput, linear photometry of V2116 Oph in a 7 Angstrom bandpass at the
center of the O I 8446 emission line. This instrumental technique shows promise
for applications requiring precise, rapid, narrowband photometry of faint
objects. The spectrum of V2116 Oph, the counterpart of GX 1+4 (=X1728-247), is
exotic, even among the unusual spectra of other optical counterparts of compact
Galactic X-ray sources. The second strongest emission line is an unusual one,
namely extremely prominent O I 8446, which is likely to result from pumping by
an intense Ly beta radiation field. As the X-radiation from GX 1+4 is steadily
pulsed, with typical pulsed fractions of 0.4, the O I 8446 emission in V2116
Oph may also be strongly modulated with the current 127 s period of the X-ray
source. If so, this may well allow us to obtain high signal-to-noise radial
velocity measurements and thus to determine the system parameters. However, no
such pulsations are detected, and we set an upper limit of ~1% (full-amplitude)
on periodic 8446 oscillations at the X-ray frequency. This value is comparable
to the amplitude of continuum oscillations observed on some nights by other
workers. Thus we rule out an enhancement of the pulsation amplitude in O I
emission, at least at the time of our observations.Comment: 9 pages including 4 figures and no tables. Accepted for publication
in PASP; to appear in Volume 110, August 199
Big Data and Analytics: Issues, Solutions, and ROI
Recently, the topic of big data and analytics has received renewed attention from academia and practitioners. There has been an increase in demand for skills in big data and analytics due to the increasing speed, variety, and volume of information. Several research reports have shown that big data and analytics remain top priority for CIOs. A recent study shows how a company accurately predicted a teen girlâs pregnancy via the companyâs big data algorithm. However, there are dark sides to big data and analytics. A panel discussion addressed topics concerning how companies ensure that big data projects clearly define measurable goals up front, methods that companies use to ensure maximum return and most effectively, and ways that companies evolve culture, processes, and technology to simultaneously maximize return. Most companies are looking at how they can effectively manage their business more through using their data assets. Companies today target an average return of $3.50 dollars for every dollar spent on big data projects. However, most are only returning a fraction of that today, which leaves room for improvement and the possibility that organizations will push back against new analytic technologies. In this paper, we cover these topics that a panel of researchers at AMCIS 2014 in Savannah, GA, discussed
Discovery of a Luminous Quasar in the Nearby Universe
In the course of the Pico dos Dias survey (PDS), we identified the stellar
like object PDS456 at coordinates alpha = 17h 28m 19.796s, delta = -14deg 15'
55.87'' (epoch 2000), with a relatively nearby (z = 0.184) and bright (B =
14.69) quasar. Its position at Galactic coordinates l_II = 10.4deg, b_II =
+11.2deg, near the bulge of the Galaxy, may explain why it was not detected
before. The optical spectrum of PDS456 is typical of a luminous quasar, showing
a broad (FWHM ~ 4000 km/s) H_\beta line, very intense FeII lines and a weak
[OIII]\lambda5007 line. PDS456 is associated to the infrared source IRAS
17254-1413 with a 60 \mum infrared luminosity L_{60} = 3.8 x 10^{45} erg/s. The
relatively flat slopes in the infrared (\alpha(25,60) = -0.33 and \alpha(12,25)
= -0.78) and a flat power index in the optical (F_{\nu} \propto \nu^{-0.72})
may indicate a low dust content. A good match between the position of PDS456
and the position of the X-ray source RXS J172819.3-141600 implies an X-ray
luminosity L_x = 2.8 x 10^{44} erg/s. The good correlation between the strength
of the emission lines in the optical and the X-ray luminosity, as well as the
steep optical to X-ray index estimated (\alpha_{ox} = -1.64) suggest that
PDS456 is radio quiet. A radio survey previously performed in this region
yields an upper limit for radio power at ~ 5 GHz of ~ 2.6 x 10^{30} erg/s/Hz.
We estimate the Galactic reddening in this line-of-sight to be A_B \simeq 2.0,
implying an absolute magnitude M_B = -26.7 (using H_0 = 75 km s^{-1} Mpc^{-1}
and q_0 = 0). In the optical, PDS456 is therefore 1.3 times more luminous than
3C 273 and the most luminous quasar in the nearby (z \leq 0.3) Universe.Comment: 12 pages, LaTeX (aasms4.sty) + 3 figures; accepted for publication in
the Astrophysical Journal Letter
Randomized trial of polychromatic blue-enriched light for circadian phase shifting, melatonin suppression, and alerting responses.
Wavelength comparisons have indicated that circadian phase-shifting and enhancement of subjective and EEG-correlates of alertness have a higher sensitivity to short wavelength visible light. The aim of the current study was to test whether polychromatic light enriched in the blue portion of the spectrum (17,000 K) has increased efficacy for melatonin suppression, circadian phase-shifting, and alertness as compared to an equal photon density exposure to a standard white polychromatic light (4000 K). Twenty healthy participants were studied in a time-free environment for 7 days. The protocol included two baseline days followed by a 26-h constant routine (CR1) to assess initial circadian phase. Following CR1, participants were exposed to a full-field fluorescent light (1 à 10 14 photons/cm 2 /s, 4000 K or 17,000 K, n = 10/condition) for 6.5 h during the biological night. Following an 8 h recovery sleep, a second 30-h CR was performed. Melatonin suppression was assessed from the difference during the light exposure and the corresponding clock time 24 h earlier during CR1. Phase-shifts were calculated from the clock time difference in dim light melatonin onset time (DLMO) between CR1 and CR2. Blue-enriched light caused significantly greater suppression of melatonin than standard light ((mean ± SD) 70.9 ± 19.6% and 42.8 ± 29.1%, respectively, p \u3c 0.05). There was no significant difference in the magnitude of phase delay shifts. Blue-enriched light significantly improved subjective alertness (p \u3c 0.05) but no differences were found for objective alertness. These data contribute to the optimization of the short wavelength-enriched spectra and intensities needed for circadian, neuroendocrine and neurobehavioral regulation
Effects of exercise and environmental complexity on deficits in trace and contextual fear conditioning produced by neonatal alcohol exposure in rats
In rodents, voluntary exercise and environmental complexity increases hippocampal neurogenesis and reverses spatial learning and long-term potentiation deficits in animals prenatally exposed to alcohol. The present experiment extended these findings to neonatal alcohol exposure and to delay, trace, and contextual fear conditioning. Rats were administered either 5.25g/kg/day alcohol via gastric intubation or received sham-intubations (SI) between Postnatal Day (PD) 4 and 9 followed by either free access to a running wheel on PD 30-41 and housing in a complex environment on PD 42-72 (wheel-running plus environmental complexity; WREC) or conventional social housing (SHSH) from PD 30 to 72. Adult rats (PD 80 +/- 5) received 5 trials/day of a 10-s flashing-light conditioned stimulus (CS) paired with .8mA footshock either immediately (delay conditioning) or after a 10-s trace interval (trace conditioning) for 2 days. Neonatal alcohol exposure impaired context and trace conditioning, but not short-delay conditioning. The WREC intervention did not reverse these deficits, despite increasing context-related freezing in ethanol-exposed and SI animals. (c) 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 483-495, 201
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Influence of a Cerium surface treatment on the oxidation behavior of commercial Fe- and Ni-base alloys
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Surface Modifications for Oxidation Resistance
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