4,294 research outputs found
The application of satellite data in the determination of ocean temperatures and cloud characteristics and statistics
The author has identified the following significant results. The major shortcoming of the data was the loss of the infrared radiances from the S191 spectrometer. The cloud thermodynamic phase determination procedure was derived and tested with the data collected by the S192 multispectral scanner. Results of the test indicate a large fraction of the data could be classified thermodynamically. An added bonus was the inclusion of snow in the classification approach. The conclusion to be drawn from this portion of the effort is that in most cases considered ice clouds, liquid water droplet clouds, and snow fields can be spectroscopically separated to a high degree of accuracy
In-situ analysis of hydrazine decomposition products
A gas analyzer utilizing a nondispersive infrared (NDIR) detection system was used to monitor the ammonia and water vapor content of the products of a previously unused hydrazine gas generator. This provided an in-situ measurement of the generator's efficiency difficult to obtain by other means. The analyzer was easily installed in both the calibration and hydrazine systems, required no maintenance other than periodic zero adjustments, and performed well for extended periods in the operating range tested. The catalyst bed operated smoothly and repeatably during the 28 hr of testing. No major transients were observed on startup or during steady state operation. The amount of ammonia in the output stream of the gas generator was found to be a strong function of temperature at catalyst bed temperatures below 450 C. At temperatures above this, the efficiency remained nearly constant. On startup the gas generator efficiency was found to decrease with time until a steady state value was attained. Elevated catalyst bed temperatures in the periods before steady state operation was found to be responsible for this phenomenon
Time evolution of the fine structure constant
We present a short review of the current quasar (QSO) absorption line
constraints on possible variation of the fine structure constant, alpha =
e^2/(hbar*c). Particular attention is paid to recent optical Keck/HIRES spectra
of 49 absorption systems which indicate a smaller alpha in the past (Murphy et
al. 2001, Webb et al. 2001). Here we present new preliminary results from 128
absorption systems: da/a = (-0.57 +/- 0.10) x 10^{-5} over the redshift range
0.2 < z < 3.7, in agreement with the previous results. Known potential
systematic errors cannot explain these results. We compare them with strong
`local' constraints and discuss other (radio and millimetre-wave) QSO
absorption line constraints on variations in alpha^2 * g_p and alpha^2 * g_p *
m_e/m_p (g_p is the proton g-factor and m_e/m_p is the electron/proton mass
ratio). Finally, we discuss future efforts to rule out or confirm the current
5.7 sigma optical detection.Comment: Invited review at the XXII Physics in Collision Conference (PIC02),
Stanford, CA, USA, June 2002, 11 pages, LaTeX, 7 eps figures. PSN FRA T0
Erratum to “ERP evidence for conceptual mappings and comparison processes during the comprehension of conventional and novel metaphors” [Brain Lang. 127 (3) (2013) 484–496]
ERP evidence for conceptual mappings and comparison processes during the comprehension of conventional and novel metaphors
Cognitive linguists suggest that understanding metaphors requires activation of conceptual mappings between the involved concepts. We tested whether mappings are indeed in use during metaphor comprehension, and what mapping means as a cognitive process with Event-Related Potentials. Participants read literal, conventional metaphorical, novel metaphorical, and anomalous target sentences preceded by primes with related or unrelated mappings. Experiment 1 used sentence-primes to activate related mappings, and Experiment 2 used simile-primes to induce comparison thinking. In the unprimed conditions of both experiments, metaphors elicited N400s more negative than the literals. In Experiment 1, related sentence-primes reduced the metaphor-literal N400 difference in conventional, but not in novel metaphors. In Experiment 2, related simile-primes reduced the metaphor-literal N400 difference in novel, but not clearly in conventional metaphors. We suggest that mapping as a process occurs in metaphors, and the ways in which it can be facilitated by comparison differ between conventional and novel metaphors
Omega-3 Fatty Acids Improve Recovery, whereas Omega-6 Fatty Acids Worsen Outcome, after Spinal Cord Injury in the Adult Rat
Spinal cord injury (SCI) is a cause of major neurological disability, and no satisfactory treatment is currently available. Evidence suggests that polyunsaturated fatty acids (PUFAs) could target some of the pathological mechanisms that underlie damage after SCI. We examined the effects of treatment with PUFAs after lateral spinal cord hemisection in the rat. The ω-3 PUFAs α-linolenic acid and docosahexaenoic acid (DHA) injected 30 min after injury induced significantly improved locomotor performance and neuroprotection, including decreased lesion size and apoptosis and increased neuronal and oligodendrocyte survival. Evidence showing a decrease in RNA/DNA oxidation suggests that the neuroprotective effect of ω-3 PUFAs involved a significant antioxidant function. In contrast, animals treated with arachidonic acid, an ω-6 PUFA, had a significantly worse outcome than controls. We confirmed the neuroprotective effect of ω-3 PUFAs by examining the effects of DHA treatment after spinal cord compression injury. Results indicated that DHA administered 30 min after spinal cord compression not only greatly increased survival of neurons but also resulted in significantly better locomotor performance for up to 6 weeks after injury.
This report shows a striking difference in efficacy between the effects of treatment with ω-3 and ω-6 PUFAs on the outcome of SCI, with ω-3 PUFAs being neuroprotective and ω-6 PUFAs having a damaging effect. Given the proven clinical safety of ω-3 PUFAs, our observations show that these PUFAs have significant therapeutic potential in SCI. In contrast, the use of preparations enriched in ω-6 PUFAs after injury could worsen outcome after SCI
Is there further evidence for spatial variation of fundamental constants?
The detection of a spatial variation of the fine-structure constant, alpha,
based on study of quasar absorption systems has recently been reported. The
physics that causes this alpha-variation should have other observable
manifestations, and this motivates us to look for complementary astrophysical
effects. In this paper we propose a method to test whether spatial variation of
fundamental constants existed during the epoch of big bang nucleosynthesis.
Using existing measurements of primordial deuterium abundance we find very weak
indications that such a signature might exist, but the paucity of measurements
precludes any firm conclusion. We also examine existing quasar absorption
spectra data that are sensitive to variation of the electron-to-proton mass
ratio, mu, and x = (alpha^2 mu g_p) for spatial variation.Comment: 6 pages, 1 figur
Mars: Mariner 9 spectroscopic evidence for H2O ice clouds
Spectral features observed with the Mariner 9 Interferometer Spectrometer are identified as those of water ice. Measured spectra are compared with theoretical calulations for the transfer of radiation through clouds of ice particles with variations in size distribution and integrated cloud mass. Comparisons with an observed spectrum from the Tharsis Ridge region indicate water ice clouds composed of particles with mean radius 2.0 microns and integrated cloud mass 0.00005 g/sq cm
Reductions of aldehydes and ketones with a readily available N-heterocyclic carbene borane and acetic acid
Acetic acid promotes the reduction of aldehydes and ketones by the readily available N-heterocyclic carbene borane, 1,3-dimethylimidazol-2-ylidene borane. Aldehydes are reduced over 1-24 h at room temperature with 1 equiv of acetic acid and 0.5 equiv of the NHC-borane. Ketone reductions are slower but can be accelerated by using 5 equiv of acetic acid. Aldehydes can be selectively reduced in the presence of ketones. On a small scale, products are isolated by evaporation of the reaction mixture and direct chromatography. © 2013 Lamm et al
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