208,624 research outputs found

    The public impact of impacts: How the media play in the mass extinction debates

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    “Mass media” presentations of the dinosaurs and their co-inhabitants have been around for some 200 years. The question of what exterminated the dinosaurs and allowed mammals to take their leading place on Earth has a similarly lengthy history in the scientific arena and in public. However, there are amazingly few communication studies of the debates around mass extinctions and impacts. Those that do exist have picked up on the fact that these debates involve scientists from several disciplines, scientists who are often unused to reading each other’s research. Under these circumstances, more public or leading journals play a key role, not only in getting ideas out into the public arena, but in informing scientists across disciplinary boundaries. “Normal” communication processes, in which articles in peer-reviewed journals inform the scientific community and “simplified” versions may trickle out to the public via the mass media, become more complex. The dramatic impact answer to the question of the death of the dinosaurs seems to have attracted limited media attention at the time, confined to the “elite” newspapers. This paper analyzes the newspaper coverage of the death of the dinosaurs during the period from 1980 to 2008. I find that the period from 1991 to 1995 was critical in terms of changing public perceptions, insofar as they are determined/reflected in articles in general newspapers. I argue that the “Great Crash of 1994,” when Comet Shoemaker-Levy 9 collided with the giant planet Jupiter, played an important role in propelling the impact scenario for the death of the dinosaurs into the (mass) public eye, and that the news value co-option was important in this process

    Cluster Growth in two- and three-dimensional Granular Gases

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    Dissipation in granular media leads to interesting phenomena as there are cluster formation and crystallization in non-equilibrium dynamical states. The freely cooling system is examined concerning the energy decay and the cluster evolution in time, both in two and three dimensions. Interesting parallels to percolation theory are obtained in three dimensions.Comment: 9 pages, 12 figure

    An efficient, simple dialyzer

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    Easily assembled, efficient, countercurrent, sandwich-type barrier dialyzer was developed. Dialyzer contains six blood chambers that provide 500 sq cm membrane area. Design membranes are cuprammonium cellulose film. Unit performance was compared with thirteen other dialyzers

    Introduction to Section on Services

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    published or submitted for publicatio

    Characteristics of ocean-reflected short radar pulses with application to altimetry and surface roughness determination

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    Current work related to geodetic altimetry is summarized. Special emphasis is placed on the effects of pulse length on both altimetry and sea-state estimation. Some discussion is also given of system tradeoff parameters and sea truth requirements to support scattering studies. The problem of analyzing signal characteristics and altimeter waveforms arising from rough surface backscattering is also considered

    Cyclic AMP modulation of ion transport across frog retinal pigment epithelium. Measurements in the short-circuit state.

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    In the frog retinal pigment epithelium (RPE), the cellular levels of cyclic AMP (cAMP) were measured in control conditions and after treatment with substances that are known to inhibit phosphodiesterase (PDE) activity (isobutyl-1-methylxanthine, SQ65442) or stimulate adenylate cyclase activity (forskolin). The cAMP levels were elevated by a factor of 5-7 compared with the controls in PDE-treated tissues and by a factor of 18 in forskolin-treated tissues. The exogenous application of cAMP (1 mM), PDE inhibitors (0.5 mM), or forskolin (0.1 mM) all produced similar changes in epithelial electrical parameters, such as transepithelial potential (TEP) and resistance (Rt), as well as changes in active ion transport. Adding 1 mM cAMP to the solution bathing the apical membrane transiently increased the short-circuit current (SCC) and the TEP (apical side positive) and decreased Rt. Microelectrode experiments showed that the elevation in TEP is due mainly to a depolarization of the basal membrane followed by, and perhaps also accompanied by, a smaller hyperpolarization of the apical membrane. The ratio of the apical to the basolateral membrane resistance increased in the presence of cAMP, and this increase, coupled with the decrease in Rt and the basolateral membrane depolarization, is consistent with a conductance increase at the basolateral membrane. Radioactive tracer experiments showed that cAMP increased the active secretion of Na (choroid to retina) and the active absorption of K (retina to choroid). Cyclic AMP also abolished the active absorption of Cl across the RPE. In sum, elevated cellular levels of cAMP affect active and passive transport mechanisms at the apical and basolateral membranes of the bullfrog RPE

    Effects of different footwear on landing forces from a grand jeté in trained dancers

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    The Grand Jete movement is a popular leap elevation movement used in ballet, modern, contemporary and jazz dance. The move involves taking off from one foot and landing on the other foot reaching the highest point possible in the air and lifting legs to a split position. Dancers may perform many grand jetes in a single routine. The aim of this study was to investigate whether footwear used by dancers can reduce the vertical impact forces caused by landing from high leaps. The study was approved by the university’s ethics committee and informed consent was given by ten highly-trained dancers (age mean 23.1, s=1.6 years; height 1.64, s=.08 m; mass 57.7, s=5.2 kg). The participants all performed a grand jete in three different footwear conditions: bare feet, jazz shoes and dance trainers with shock absorbing properties. Landing forces were recorded using a Kistler force plate sampling at 1000 Hz. Peak impact force was determined as the maximum vertical force occurring during the first 0.07 s of contact. Statistical analysis consisted of repeated measures ANOVA. Maximumforce during the landing phase decreased from 4.00 BW (s=0.72) in the barefoot condition to 3.95 BW (s=0.69) in the jazz shoes condition and 3.58 BW (s=0.68) in the trainers condition (F2,9=2.5, P=0.108, Z2=0.22, power=0.44).Higher impact peak and loading rate values were found in the barefoot condition compared to the shodconditions, with the trainers showing the lowest values. However, there were no significant differences between the footwear conditions for impact peak force(F2,9=0.50, P¼0.616, Z2=0.05, power=0.12),time-to-peak impact force (F2,9=0.44 , P=0.653, Z2=0.05, power=0.11), or loading rate to the poin of maximum vertical force (F2,9=0.53, P=0.597, Z2=0.06, power=0.12). The results showed lower maximum landing forces, impact peak force and loading rates in the dance trainers compared to the barefoot and jazz shoes conditions. Although the values were not significantly different, the small difference between footwear conditions may prove important with the onset of fatigue during a routine. Dancers should train to develop safe landing techniques when performing barefooted
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